Fuzzy age-dependent replacement policy and SPSA algorithm based-on fuzzy simulation

An increase in the performance of deteriorating systems can be achieved through the adoption of suitable maintenance policies. One of the most popular maintenance policies is the age-dependent replacement policy. In this paper, a fuzzy agedependent replacement policy is considered in which the lifetimes of components are treated as fuzzy variables. To minimize the long-term expected cost per unit time, a programming model is formulated. Also, a theorem for optimal solution existence is proposed. In order to solve the proposed model, a fuzzy simulation technique is designed which estimates the expected value of the objective function. The simultaneous perturbation stochastic approximation (SPSA) algorithm is then used to determine a solution. Finally, a numerical example is presented to illustrate the effectiveness of this technique. 2007 Published by Elsevier Inc.