Comparisons Of Component Redundancy Versus System Redundancy In Coherent System

In this thesis, we treat the problem of stochastic comparison of standby [ac-tive] redundancy at component level versus system level. In the case of standby redundancy, we present some interesting comparison results of series system and parallel system in the sense of various stochastic orderings for both the matching case and non-matching case, respectively. In the case of active redundancy, a like-lihood ratio ordering result of series system is presented for the matching spares; and for the non-matching spares, a counterexample is provided to illustrate that there does not exist similar result even for the hazard rate ordering. The results established here strengthen and generalize some of those known in the literature. Some numerical examples are also provided to illustrate the theoretical results.