In my dissertation, I developed models for locating and protecting facilities that are subject to disruptions caused by attacks from an adversary (i.e., interdictions) or random events (e.g., natural disasters). My dissertation made several contributions:

  1. The problem of designing and protecting networks subject to interdictions is often modeled using a tri-level mathematical program. We showed that the minimax facility location problem with interdiction can be solved very efficiently using a single-level model due to the problem structure.
  2. We contributed a model and efficient solution procedure for making facility location and facility hardening decisions in tandem.
  3. We studied a new facility protection problem in which allocating resources to a facility only has a probabilistic effect on the facility’s post-disruption capacity. We modeled this problem as a two-stage stochastic program with endogenous uncertainty and solved it using a greedy algorithm with a performance guarantee and the L-shaped method.

Complementing my dissertation, I have done other work on designing and protecting networks. I have coauthored a literature review on network vulnerability. In another project, my co-authors and I addressed the need for network disruption models with multiple objectives such as cost, efficiency, and risk]. Finally, I have also done work on using a bi-level optimization model to compute the vulnerability of a unit-train railway network.

One of my Ph.D. students and I have completed a study on using fault trees to model disruptions in a supply chain. We are currently working on developing algorithms for optimizing the allocation of resources to minimize the probability that a fault occurs. Future potential funding sources for this work include the National Science Foundation, the Department of Homeland Security, and the Naval Postgraduate School’s Acquisition Research Program.

Selected Publications

  1. An optimized resource allocation approach to identify and mitigate supply chain risks using fault-tree analysis
    Sherwin, M., Brown, K. J., Medal, H., and Mackenzie, C.. IISE Transactions 52(2). to appear, 236–254.
    Publication Year: 2020
    Abstract
  2. A Model-Based Systems Engineering Approach to Critical Infrastructure Vulnerability Assessment and Decision Analysis
    Huff, J. D., Medal, H., and K. A. Griendling. Submitted to Systems Engineering 22(2), 114–133.
    Publication Year: 2019
    [Link to Article] Abstract
  3. NATO Human View Executable Architectures for Critical Infrastructure Analysis
    Huff, J. D., Leonard, W., B. Smith, K. Griendling, and Medal, H.. Engineering Management Journal. 31:4, 224-245.
    Publication Year: 2019
    [Link to Article] Abstract
  4. Proactive Cost-Effective Risk Mitigation in a Low Volume High Value Supply Chain Using Fault-Tree Analysis
    Michael D. Sherwin, Hugh Medal, Steven A. Lapp. International Journal of Production Economics, Volume 175, Pages 153–163
    Publication Year: 2016
    [PDF]   [Link to Article] Abstract
  5. A Bi-objective Analysis of the R-All-Neighbor P-Center Problem
    Hugh R. Medal, Chase E. Rainwater, Edward A. Pohl, Manuel D. Rossetti. Computers & Industrial Engineering, Volume 72, Pages 114–128
    Publication Year: 2014
    [PDF]   [Link to Article] Abstract
  6. A Multi-objective Integrated Facility Location-Hardening Model: Analyzing the Pre- and Post-Disruption Tradeoff
    Hugh R. Medal, Edward A. Pohl, Manuel D. Rossetti. European Journal of Operational Research, Volume 237, 257– 270
    Publication Year: 2014
    [PDF]   [Link to Article] Abstract
  7. Robust Facility Location: Hedging Against Failures
    Ivan Hernandez, Jose Emmanuel Ramirez-Marquez, Chase Rainwater, Edward Pohl, Hugh Medal. Reliability Engineering & System Safety, Volume 123, Pages 73–80
    Publication Year: 2014
    [PDF]   [Link to Article] Abstract
  8. Vulnerability Assessment and Re-routing of Freight Trains Under Disruptions: A Coal Supply Chain Network Application
    Ridvan Gedik, Hugh Medal, Chase Rainwater, Ed A. Pohl, Scott J. Mason. Transportation Research Part E, Volume 71, 45–57
    Publication Year: 2014
    [PDF]   [Link to Article] Abstract
  9. Models for reducing the risk of critical networked infrastructures
    Hugh Medal, Stevenson J. Sharp, Ed Pohl, Chase Rainwater, Scott J. Mason. International Journal of Risk Assessment and Management, Volume 15 (No. 2/3), Pages 99-127
    Publication Year: 2011
    [PDF]   [Link to Article] Abstract