3 research outputs found
On Component Redundancy Versus System Redundancy for a -out-of- System
Precedence order is a natural type of comparison for random variables in
numerous engineering applications (e.g., for the stress-strength modeling). In
this note, we show that, for a -out-of- system, redundancy at the
component level is superior to that at the system level with respect to the
stochastic precedence order. Cases of active and cold redundancy are
considered. Similar results for other stochastic orders were intensively
discussed in the literature
Allocations of Cold Standbys to Series and Parallel Systems with Dependent Components
In the context of industrial engineering, cold-standby redundancies
allocation strategy is usually adopted to improve the reliability of coherent
systems. This paper investigates optimal allocation strategies of cold standbys
for series and parallel systems comprised of dependent components with
left/right tail weakly stochastic arrangement increasing lifetimes. For the
case of heterogeneous and independent matched cold standbys, it is proved that
better redundancies should be put in the nodes having weaker [better]
components for series [parallel] systems. For the case of homogeneous and
independent cold standbys, it is shown that more redundancies should be put in
standby with weaker [better] components to enhance the reliability of series
[parallel] systems. The results developed here generalize and extend those
corresponding ones in the literature to the case of series and parallel systems
with dependent components. Numerical examples are also presented to provide
guidance for the practical use of our theoretical findings.Comment: 28 page
On Relative Ageing of Coherent Systems with Dependent Identically Distributed Components
Relative ageing describes how a system ages with respect to another one. The
ageing faster orders are the ones which compare the relative ageings of two
systems. Here, we study ageing faster orders in the hazard and the reversed
hazard rates. We provide some sufficient conditions for proving that one
coherent system dominates another system with respect to ageing faster orders.
Further, we investigate whether the active redundancy at the component level is
more effective than that at the system level with respect to ageing faster
orders, for a coherent system. Furthermore, a used coherent system and a
coherent system made out of used components are compared with respect to ageing
faster orders