Optimization multi -state series weighted k-out-of-n systems by ant colony algorithm

In this paper a multi state series-weighted k-out-of-n system is presented. This system has S multi state weighted k-out-of-n subsystems that are seriely connected. A new approach is used for calculating reliability of the system. In this approach first we find reliability of each subsystem by recursive algorithm, and then the universal moment generating function (UMGF) is used to calculate reliability of the whole system. In the following reliability of the system is optimized. Multi-state system (MSS) reliability is defined as the ability to maintain a specified performance level. Objective function in the optimization model is maximizing the reliability of the system, constraint is cost and weight of the system and decision variables are the number and the versions of components for each subsystem. Since this problem is a combinatorial and Np-hard problem, ant colony algorithm is used for optimization.