ScienceDirect


        
    
        
            
                    
                        
                        
                            


                    
                        	Journals &
                                        Books


                    
                    
                        	
                                        
                                            
                                            
                                        




            
    
    

    
    
        
            
                
                    
                        ! There was a problem providing the content you requested
                    

                    
                        Please contact us via our
                            support center for more information and provide the details below.
                    

                    
                        
                            Reference Number: 780cede8288620cd
                        

                        
                            IP Address: 129.74.145.123
                        

                        Timestamp:

                    

                    
                        
  Access denied

  You do not have access to www.sciencedirect.com.
The site owner may have set restrictions that prevent you from accessing the site.

  	Ray ID: 780cede8288620cd
	Timestamp: 2022-12-28 20:08:40 UTC
	Your IP address: 129.74.145.123
	Requested URL: www.sciencedirect.com/science/article/pii/S2212977419300444 
	Error reference number: 1020
	Server ID: FL_154F20
	User-Agent: python-requests/2.28.1





                    

                    
                

            

        

    

    
    
        
            

            
                            


                    
                        About ScienceDirect
                        Shopping cart
                        Contact and
                                supportTerms and
                                conditionsPrivacy policy

                    We use cookies to help provide and enhance our service and tailor content and ads. By continuing you agree to the
                        use of
                                cookies.

                    Copyright ©
                        2020
                        Elsevier B.V. or its licensors or contributors. ScienceDirect ® is a registered trademark of Elsevier B.V.