Sharif Digital Repository

In this paper, a new method for path planning is proposed using a genetic algorithm (GA). Our method has two key advantages over existing GA methods. The first is a novel environment representation which allows a more efficient method for obstacles dilation in comparison to current cell based approaches that have a tradeoff between speed and accuracy. The second is the strategy we use to generate the initial population in order to speed up the convergence rate which is completely novel. Simulation results show that our method can find a near optimal path faster than computational geometry approaches and with more accuracy in smaller number of generations than GA methods. © 2009 IEEE  

Nowadays, content distribution is of high attention in peer to peer information systems. There are two main problems that could be mentioned in this context. The first problem is how to disseminate fragments of information efficiently and the next is to avoid missing same rare fragments towards end of download. For overcoming these problems, a new mechanism is presented in this paper which uses gossip algorithms on basis of social networks. Our mechanism maintains simplicity of gossip and has low overhead. This mechanism includes two phases for managing traffic and solving bottleneck problem: one for spreading rumors inside the social network and finding network of interests and the other... 

In recently proposed cipher algorithms, power functions over finite fields and specially inversion functions play an important role in the S-box design structure. In this study, a new systematic efficient method is introduced to cryptanalyse (to simplify and approximate) such S-boxes. This method is very simple and does not need any heuristic attempt and can be considered as a quick criterion to find some simple approximations. Using this new method, some approximations can be obtained for advanced encryption standard (AES) like S-boxes, such as AES, Camellia, Shark and so on. Finally as an application of this method, a simple linear approximation for AES S-box is presented. © The... 

Purpose: The purpose of this paper is to present a new efficient method for the tolerance–reliability analysis and quality control of complex nonlinear assemblies where explicit assembly functions are difficult or impossible to extract based on Bayesian modeling. Design/methodology/approach: In the proposed method, first, tolerances are modelled as the random uncertain variables. Then, based on the assembly data, the explicit assembly function can be expressed by the Bayesian model in terms of manufacturing and assembly tolerances. According to the obtained assembly tolerance, reliability of the mechanical assembly to meet the assembly requirement can be estimated by a proper first-order...