A System with Two Spare Units, Two Repair Facilities, and Two Types of Repairers

Date

2022-03-08

Department

Program

Citation of Original Publication

Andalib, Vahid, and Jyotirmoy Sarkar. 2022. "A System with Two Spare Units, Two Repair Facilities, and Two Types of Repairers" Mathematics 10, no. 6: 852. https://doi.org/10.3390/math10060852

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Attribution 4.0 International (CC BY 4.0)

Subjects

Abstract

Assuming exponential lifetime and repair time distributions, we study the limiting availability A∞ as well as the per unit time-limiting profit ω of a one-unit system having two identical, cold standby spare units using semi-Markov processes. The failed unit is repaired either by an in-house repairer within an exponential patience time T or by an external expert who works faster but charges more. When there are two repair facilities, we allow the regular repairer to begin repair or to continue repair beyond T if the expert is busy. Two models arise accordingly as the expert repairs one or all failed units during each visit. We show that (1) adding a second spare to a one-unit system already backed by a spare raises A∞ as well as ω; (2) thereafter, adding a second repair facility improves both criteria further. Finally, we determine whether the expert must repair one or all failed units to maximize these criteria and fulfill the maintenance management objectives better than previously studied models.