id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
ap-992	Matz, V.; Kreidl, M.; Šmíd, R.	Signal Separation in Ultrasonic Non-Destructive Testing	2007	7	.pdf	application/pdf	4368	222	61	H x x i x c H mat k k k k l ( ) exp( ) exp ( � � � � � � � � � � � � � �� � � �� � 2 42 2 ) ( ),� � � H k Ktot � 1 (8) where � is the material attenuation coefficient, cl is the veloc- ity of the longitudinal waves, xk is the grain positions of k K tot�1� is the number of grains and �k is a random vector depending on the grain volume. [9] based on group delay statistics are the group delay moving standard deviation � ��k k m k M k M T m T� � � � � � � � � �� � �1 1 2 1 2 � �( ) (4) and the group delay moving entropy H f T f Tk j j j	cache/ap-992.pdf	txt/ap-992.txt