Operational resilience: concepts, design and analysis

Building resilience into today’s complex infrastructures is critical to the daily functioning of society andits ability to withstand and recover from natural disasters, epidemics, and cyber-threats. This studyproposes quantitative measures that capture and implement the definition of engineering resilienceadvanced by the National Academy of Sciences. The approach is applicable across physical, information,and social domains. It evaluates the critical functionality, defined as a performance function of time setby the stakeholders. Critical functionality is a source of valuable information, such as the integratedsystem resilience over a time interval, and its robustness. The paper demonstrates the formulation ontwo classes of models: 1) multi-level directed acyclic graphs, and 2) interdependent coupled networks.For both models synthetic case studies are used to explore trends. For the first class, the approach isalso applied to the Linux operating system. Results indicate that desired resilience and robustness levelsare achievable by trading off different design parameters, such as redundancy, node recovery time, andbackup supply available. The nonlinear relationship between network parameters and resilience levelsconfirms the utility of the proposed approach, which is of benefit to analysts and designers of complexsystems and networks