Skip to content Skip to main navigation Report an accessibility issue

Optimally Replacing Multiple Systems in a Shared Environment

Jeffrey P Kharoufeh, Ph.D.
Professor & Chair
Department of Industrial Engineering
Clemson University
Friday, March 13, 2020  2:30-3:30 PM
410 Tickle Building



In this talk, we consider the problem of optimally replacing multiple stochastically degrading systems using condition-based maintenance. These systems exhibit stochastic dependencies due to their shared environment, as well as economic dependencies due to similar maintenance resource requirements. Each system degrades continuously at a rate that is governed by the current state of the environment, and each fails once its own cumulative degradation threshold is reached. The objective is to minimize the sum of the expected total discounted setup, preventive replacement, reactive replacement, and downtime costs over an infinite horizon. For each distinct environment state, we prove that the cost function is monotone non-decreasing in the cumulative degradation level. Additionally, under mild conditions, these monotonicity results are extended to the entire state space. In the case of a single system, we establish that monotone policies are optimal. The monotonicity results help facilitate a tractable approximate model with state- and action-space transformations and a basis-function approximation of the action-value function. A computational study demonstrates that high-quality, near-optimal policies are attainable, and these policies significantly outperform simple heuristics.



Jeffrey P. Kharoufeh is Professor and Chair of the Department of Industrial Engineering at Clemson University.  His methodological areas of expertise are applied probability and stochastic modeling with applications in energy systems, queueing, reliability and maintenance optimization.  His research has been funded by the National Science Foundation, the Air Force Office of Scientific Research, the National Reconnaissance Office, the Department of Veterans Affairs and other federal agencies.  Dr. Kharoufeh earned a Ph.D. in Industrial Engineering and Operations Research from the Pennsylvania State University, where he was an inaugural Weiss Graduate Fellow. He currently serves as an Associate Editor of Operations Research, Area Editor of Operations Research Letters and as a member of the editorial board of Probability in the Engineering and Informational Sciences. He is a Fellow of IISE and a professional member of INFORMS and the Applied Probability Society.