SoSRM: A New Metric to Standarize System-of System Resilience Evaluation

Abstract

Modern Life is enhanced by Systems of Systems (SoS). Financial systems, power infrastructure, transportation networks, and other SoS synergistically combine the resources and services of their constituent systems. Resilience measures SoS's ability to withstand faults, minimize service disruption, and efficiently recover. Current SoS resilience metrics, however, require improvement. Because each SoS is approached with different assumptions about fault magnitude and recovery strategy, the resilience research community currently has difficulty answering the basic question: Between alternative designs A and B which system is more resilient? A new SoS Resilience metric should reflect that the most potent leverage point for SoS is at the system interfaces, incorporate a standardized fault and recovery strategy, be easily understood by decision makers, incorporate SoS dynamics, and be applicable to both Ecosystems and Industrial SoS. In response, we develop the SoS Resilience Metric (SoSRM). SoSRM methodology uses the definition of SoS to identify appropriate fault locations and Ecological Network Analysis to define fault and recovery duration. As an example application, SoSRM is applied an Intertidal Oyster Reef Ecosystem's System Dynamics Model. Validation simulations demonstrate that SoSRM reflects expected fault impact. Additionally, methodological choices for fault duration do not drive SoSRM calculation results. This work presents a new tool with the end goal of examining two SoS to identify the more resilient.