Table of Contents
Journal of Quality and Reliability Engineering
Volume 2014, Article ID 896379, 13 pages
Research Article

Stochastic Analysis of a Two-Unit Cold Standby System Wherein Both Units May Become Operative Depending upon the Demand

1Department of Applied Sciences, Chitkara University, Rajpura, Punjab 140401, India
2Department of Mathematics, Maharshi Dayanand University, Rohtak, Haryana 124001, India

Received 16 June 2014; Revised 13 October 2014; Accepted 28 October 2014; Published 1 December 2014

Academic Editor: Yi-Hung Chen

Copyright © 2014 Reetu Malhotra and Gulshan Taneja. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The present paper analyzes a two-unit cold standby system wherein both units may become operative depending upon the demand. Initially, one of the units is operative while the other is kept as cold standby. If the operative unit fails or the demand increases to the extent that one operative unit is not capable of meeting the demand, the standby unit becomes operative instantaneously. Thus, both units may become operative simultaneously to meet the increased demand. Availability in three types of upstates is as follows: (i) when the demand is less than or equal to production manufactured by one unit; (ii) when the demand is greater than whatever produced by one unit but less than or equal to production made by two units; and (iii) when the demand is greater than the produces by two units. Other measures of the system effectiveness have also been obtained in general case as well as for a particular case. Techniques of semi-Markov processes and regenerative processes have been used to obtain various measures of the system effectiveness.