Components in cold-standby state are usually assumed to be as good as new when they are activated. However, even in a standby environment, the components will suffer from performance degradation. This article presents a study of a redundancy allocation problem (RAP) for cold-standby systems with degrading components. The objective of the RAP is to determine an optimal design configuration of co...

Redundancy allocation problems (RAPs) have attracted much attention for the past thirty years due to its wide applications in improving the reliability of various engineering systems. Since RAP is an NP-hard problem and exact methods are only applicable to small instances, various heuristic and meta-heuristic methods have been proposed to solve it. In the literature, most studies on RAPs have b...

The bat algorithm is a recently proposed meta-heuristic algorithm. Usually in solving the problem of optimization, the position of virtual bats is updated by flying speed, which decreases efficiency of the algorithm and accuracy of the solution. This paper has improved the location update strategy and individual selection strategy of bat algorithm, then puts forward an improved bat algorithm. T...

In this paper, we deal with a multi-level redundancy allocation problem for a multi-level system and system, modules and component levels in the system are simultaneously considered as candidates for redundancy. System availability and life cycle cost are used as the constraint and objective function, respectively, and are estimated by simulation. The level and degree of redundancy are determin...

This paper presents a new mathematical model of a redundancy allocation problem with mixing components redundant in subsystems of a series-parallel system when the redundancy strategy can be chosen for individual subsystems. In practice both active and coldstandby redundancies are used within a particular system design, and the choice of the redundancy strategy becomes an additional decision va...

In this paper, a hybrid TS-DE algorithm based on Tabu search and differential evolution algorithm is proposed to solve the reliability redundancy optimization problem. A differential evolution algorithm is embedded in Tabu search algorithm. TS is applied for searching solutions space, and DE is used for generating neighborhood solutions. The advantages of both algorithms are considered simultan...

With the popularity of multilevel design in large scale systems, reliability redundancy allocation on multilevel systems is becoming attractive to researchers. Multilevel redundancy allocation problem (MLRAP) is not only NP-hard, but also qualifies as hierarchy optimization problem. Exact method could not tackle MLRAP very well, so heuristic and meta-heuristic methods are often used to solve it...

A new column generation decomposition algorithm is described and demonstrated to determine efficient solutions for the reliability-redundancy allocation problem. The problem is a well-known nonlinear mixed integer programming problem which involves the maximization of system reliability by simultaneously selecting component reliability levels and redundancy levels as part of systems engineering...