Input-output inoperability risk model and beyond: A holistic approach

Assessing and managing risks inherent in a set of large-scale, complex engineered systems (such as critical infrastructures) due to the intra- and interdependency are important from both theoretical and practical standpoints. In this research, we lay out a framework based on the notion of Input-Output that can help describe and manage such risks as well as their propagation and proliferation. Our fundamental assumption is that the total risk, expressed in terms of equilibrium inoperability, is the joint effect of an initial perturbation and the interdependency inherent in the system.; The overall goal is accomplished through completion of the following: (1) Develop a general methodology for identifying sources of risks confronted by large-scale, complex engineered systems. This process builds on the philosophy and methodology of the Hierarchical Holographic Modeling. It is proposed that the risk identification process is marked by three steps and the final product is characterized by a combinatorial mapping of the hazard HHM onto the system HHM. (2) Develop a perturbation-based inoperability risk model for interdependent complex systems based on Leontief's concept of input and output and earlier work by Haimes and Jiang. The notion of inoperability is further developed as a general risk metric to enable a unified conceptual approach in the modeling framework. The notion of derivative inoperability is introduced to capture the consequences of an initial structural inoperability resulting from an attack. (3) The concepts of influence set and reliance set are introduced to describe system connectivity. Based upon these concepts, inoperability influence diagram is used to show the propagation of inoperability over time triggered by an initial disturbance, and inoperability proliferation factor is used to capture the increase in inoperability in a truly bidirectional system. (4) Develop a risk management methodology that aims at minimizing the derivative inoperability of a set of serially interdependent systems according to prioritized objectives. We applied this methodology to a Leontief-based economic system, through a case featuring 12 economic sectors where derivative inoperability is manifested as derivative economic loss. It is shown that the total economic loss is significantly reduced by applying the risk management strategy. (Abstract shortened by UMI.)...