The lifetimes of two-component series systems with two active redundancies are compared using the hazard rate and the reversed hazard rate orders. We study the problem of where to allocate the spares in a system to obtain the best configuration. We compare redundancy at component level vs....

We compare the lifetimes of series systems with different allocations of active redundancy using a variety of stochastic comparisons. It is assumed that only one spare can be allocated to each component of the system.