Reliability measure of an integrated H/W and S/W system with redundancy and preventive maintenance

Abstract

The purpose of the study is to evaluate the reliability measures of an integrated $\mathrm{h} / \mathrm{w}$ and $\mathrm{s} / \mathrm{w}$ system with the concepts of redundancy and preventive maintenance. A stochastic model is developed considering two-identical units of the system- one unit is initially operative and other is in cold standby. In each unit $\mathrm{h} / \mathrm{w}$ and s/w work together and may fail independently from normal mode. There is a single server who visits the system immediately to $\mathrm{h} / \mathrm{w}$ repair and $\mathrm{s} / \mathrm{w}$ up-gradation. The preventive maintenance of the system (unit) is conducted by the server after a maximum operation time. The failure time of $\mathrm{h} / \mathrm{w}$ and $\mathrm{s} / \mathrm{w}$ follows negative exponential distribution while the distributions of preventive maintenance, $\mathrm{h} / \mathrm{w}$ repair and $\mathrm{s} / \mathrm{w}$ up-gradation times are taken as arbitrary. The semi-Markov process and regenerative point technique is adopted to derive expressions for various measures of system effectiveness. The behaviour of some important reliability measures has been observed graphically giving particular values to various costs and parameters.