23 Journal of Mathematics and Computer Science 7 (2013) 23 – 32 Simulation and Optimization of Affective Causes on Quality of Electronic Services Mohammadali Pirayesh Neghab Iran University of Ferdowsi , Faculty of Industrial Engineering pirayesh@ferdowsi.um.ac.ir e Shahrzad Mohsenian Heravi Iran University of Ferdowsi , Faculty of Industrial Engineering shmoseniyan@gmail.com Mohsen Kahani Iran University of Ferdowsi , Faculty of Computer Engineering kahani@ferdowsi.um.ac.ir Article history: Received February 2013 Accepted March 2013 Available online April 2013 Abstract By expanding bank services and increment in access requests for information resources, web servers perform weak about response time. So it is necessary to use simulation and mathematical models in order to analyzing complicated systems, optimizing and managing web server systems. In this paper, services which are offered through internet are introduced and analyzed as a queue. Web servers are one of the main and effective parts in quality of internet services. Therefore, the operation of web servers is analyzed and optimized by concept of queue and simulation. One of the significant points in this paper is analyzing a problem taken from real world in internet field and also performing a new analysis from user’s requests in web servers. The main purpose in this paper is to persuade users and answering theme as soon as possible. In this paper, after introducing the problem’s structure, simulation and queue concept are used for analyzing, optimizing and managing web servers. Finally, a summery from results of simulation’s calculation is declared. Keywords: Simulation, Optimization, Queuing theory, Quality of service, Web server, Response time.