Optimisation of parallel systems subject to two modes of failure with repair provision

A parallel redundant system with N-identical components is considered. Each component and the system itself are subject to two modes of failure, open and short. The authors assume that the system is repaired after each system failure and the successive repair times after failure constitute a non-decreasing geometric process. They develop a procedure leading to the optimal number of units (N*) for the system, based on cost considerations. Numerical examples are given to illustrate the results.