Vulnerability Analysis Of Infrastructure Systems Based On Complex Network Theory

Infrastructure systems are the framework of material engineering facilities thatprovide service for the social production and the resident’s life. It is the general materialcondition of survival and development for society. It is a topical complex system.Societies today are increasingly dependent on such systems to maintain normal operation.However, events of recent years such as the North American blackout and the ChineseSouthern snowstorm have raised alarms in regards to overall safety. In view of theimportance of infrastructure systems for social well-being and sustenance, studyingresponse of infrastructure systems under different types of disturbances, analyzing,understanding and identifying vulnerability of infrastructure systems for the purpose ofimprovement, has become a focal area for the process of optimizing infrastructure designand protection.Utilizing IIM, system dynamics model and agent simulation model, manyauthoritative agencies and researchers have made an research on the tender inside theinfrastructure systems, and discussed the disaster affection to the economic system,functional device and the business processes, etc. But the researchers only get certainpreliminary achievements because of the complexity of infrastructure systems. Therefore,the study in vulnerability analysis of infrastructure systems has been at the beginning stagewithout forming a complete theoretical and methodological system.As abstraction of many real complex systems, complex network theory has beenapplied to the area of mathematics, life sciences and engineering. It thus provides a newperspective and applied research method to vulnerability analysis of infrastructure systems,allowing a level of analysis that can approach the overall complexity and dynamics ofinfrastructure systems. Using the theory and method of complex networks, this paperstudies the vulnerability of infrastructure systems, starting from a single system and thenprogressing to interdependent systems. Main contributions of this dissertation aresummarized as follows:First, this paper gives the theoretical framework for vulnerability analysis, andanalyses the complexity of infrastructure systems. Combined with the theories and methods of complex network, topology description and functional characterizations ofinfrastructure systems are studied. Meanwhile, to give a more profound understanding ofthe structural and functional features of the infrastructure systems, parameters such asclustering coefficient, degree, and betweenness are introduced and summarized.Because vulnerability analysis of single infrastructure systems often focuses on nodecascading failures and the impact of external factors (such as natural disasters,) edgecascading failures, community structure implementation and community structuralvulnerabilities are rarely mentioned. This article establishes a model of edges cascadingfailures, and analyses the vulnerability of infrastructure systems. Meanwhile, a communitydetection method and vulnerability metric are proposed to locate the weakest and mostrobust communities.Interdependent infrastructure system vulnerability analysis is a relatively new area ofresearch. Current research in this area has not yet reached maturation of theory andmethodology, especially in the field of modeling. Thus, this paper first studies theinfrastructure system from different aspects such as interdependency types, operationstates, infrastructure characteristics, failure types, coupling and response behavior, andinfrastructure environment. It then establishes a framework for vulnerability analysis.The purpose of vulnerability analysis is to better protect the infrastructure systems.On the basis of vulnerability analysis on single and interdependent infrastructure systems,by considering the performance loss of systems undergoing edge or node failures, keycomponents of an infrastructure system are proposed and identified and networkinterventions as well as improvement strategies are discussed to better protect theinfrastructure systems.