Abstract. Cyber-physical systems are often differentiated from other real-time embedded systems based on the tight intertwining of the cyber infrastructure with the physical components upon which it exerts control. This close interaction manifests as interdependence in operation and failure. On the positive side, cyber-physical interdependence can fulfill the promise of more reliable and efficient operation. However, the same tight intertwining that can yield this fortification and efficacy is a vulnerability that can allow propagation of failures or attacks from cyber to physical components or vice versa. We seek to quantify this potentially detrimental effect of interdependency on the reliability of a cyber-physical system. We determine and quantify the type and extent of dependency in the system using a method based on the analytic network process, from multi-criteria decision analysis. We subsequently present a quantitative reliability model using the Markov chain imbeddable systems technique that characterizes the effect of the interdependence on degrading the reliability of the system. As an illustrative example, we apply the proposed approach to a smart grid based on the IEEE 14-bus system.

Short Bio. Dr. Sahra Sedigh Sarvestani is an Associate Professor of Electrical and Computer Engineering and Computer Science and a Research Investigator with the Intelligent Systems Center at the Missouri University of Science and Technology. She received the B.S. degree from the Sharif University of Technology and the M.S. and Ph.D. degrees from Purdue University, all in electrical engineering. Her current research centers on development and modeling of dependable networks and systems, with focus on critical infrastructure. Her projects include research on dependability of the electric power grid, large-scale water distribution networks, and transportation infrastructures. Her past and present research sponsors include the US and Missouri Departments of Transportation, the Department of Education, the National Security Agency, and the EU FP7 Program on Smart Monitoring of Historic Structures. She is a Fellow of the National Academy of Engineering's Frontiers of Engineering Education Program and held a Purdue Research Foundation Fellowship from 1996 to 2000. She is a member of HKN, IEEE, and ACM.