Optimal Replacement Policy Based on the Number of Down Times with Priority in Use

This paper is an extension of the paper “Optimal Replacement Policy Based on Number of Down Times” of the authors, which was published in EQC 25/1. While the former investigated a cold standby system consisting of two identical components, the present one considers the same situation, however, with two unequal components. The first component is very reliable while the second one is less reliable. Just as in the previous paper, a replacement policy based on the number of down times in a renewal cycle is determined that maximizes the long run expected reward per unit time. The explicit expression of the long run expected reward per unit time is derived and a numerical example is given for illustration.