An integrated tri-level model for enhancing the resilience of facilities against intentional attacks

It is paramount to enhance the resilience of many facilities that are known to be critical for modern societies and threatened by intentional attacks. For this purpose, it is important to not only protect them before disruptions, but also recover them after disruptions. To deal with this problem, this paper proposes a tri-level model explicitly integrating the decision making on recovery strategies of disrupted facilities with the decision making on protecting facilities from intentional attacks. The facilities studied in this research are assumed to be capacitated and a recovery strategy is considered to include repairing a subset of disrupted facilities and expanding the capacities of a subset of non-interdicted facilities. We are concerned with the defender's objective of maximizing the resilience of the given set of facilities making profit within a prescribed time interval. To deal with the complexity of solving the proposed tri-level model, the ant colony system algorithm is employed with necessary adaptations.