Vulnerability Assessment Methods For Urban Critical Infrastructure System

From ancient times to the present,urban has been a settlement for large populations,and as the center of politics,economy and culture of a country and region,it has played an important role in the national economic and social development.Taking full use of the important role of the urban has become the primary task of building a modern socialist country,which has a global and long-term strategic significant.In the urban,including critical infrastructure system which is mainly composed by a set of power network,transportation network,water supply network,drainage network and energy network,has a close relationship with the national security,economic development and people's normal life,and they are the material bases for people to survive.However,in recent years,human social disasters occurred frequently,which has caused the damage of CIS,and then the relevant services will also be damaged.If that cannot be solved or controlled timely,under the action of the complexity,uncertainty,relevance and other factors,it can lead to large-scale secondary disasters,and bring greater losses for the country the society,therefore,people should take the necessary measures to protect the urban critical infrastructures.In the field of public management and public security,a large number of facts show that the urban CIS great loss degree and weak resistance ability in social disasters are not entirely from social disasters,but also depends on the vulnerability of CIS itself,in particular,the urban CIS internal interdependent effect leads to the enhance of vulnerability,so reducing the vulnerability of system is one of the effective ways to protect the urban CIS.Based on the complex network theory and disaster theory,the connotation and characteristics of the urban CIS is analyzed,the urban critical infrastructures are divided into two types including strong one and week one by different structure of urban critical infrastructures,and this is a deep understanding of the vulnerability of the source and mechanism of urban CIS.The paper studies the vulnerability assessment method of urban critical infrastructure system from the view of system theory taking critical infrastructures interdependent as clues.First of all,urban CIS interdependent is modeling.According to the characteristics of the interdependent within the urban CIS,using structured method,formal method and ontology method,research the interdependent of urban CIS fully from different angles step by step.This can lay a solid foundation for urban CIS vulnerability assessment.Secondly,urban CIS nodes vulnerability assessment method.According to the characteristics of urban CIS,abstracts the single critical infrastructure for nodes,using the improved PageRank algorithm to measure the importance of nodes from the three aspects of structure importance,position importance and economic importance.With a new perspective to measure urban CIS vulnerability,this make evaluation results more comprehensive,objective and effective.Thirdly,urban CIS single-interdependent style vulnerability assessment method.Divided urban CIS interdependent into three types and two styles,three types are geographical interdependent,physics interdependent and information interdependent;two styles are single-interdependent and multi-interdependent.On the basis of given a single-interdependent definition,proposed three vulnerability assessment models.(1)Urban CIS geographical interdependent vulnerability assessment method.According to the definition of geographical interdependent at the background of gravity model,measures urban CIS geographical interdependent vulnerability by three variables of distance,scale of critical infrastructure body and Geological factor.(2)Urban CIS physical interdependent vulnerability assessment method.Because each urban critical infrastructure has different functions and tasks in the process of physical resources transmission,the urban critical infrastructure can be divided into three types including production critical infrastructure,delivery critical infrastructure and cost critical infrastructure;Builds urban CIS physical interdependent network taking “production-consumption” of physical resources as the driver and divides the physical interdependent into two types which name shared physical interdependent and dispersive physical interdependent according to the difference of connection type;establishes vulnerability assessment model using three indicators of connectivity,change rate of normal state,transmission efficiency combing with diverse methods.(3)Urban CIS information interdependent vulnerability assessment method.Extending Petri nets semantic,establish urban CIS information network attack graph combing with infiltration theory.Form three aspects of attack graph,attack damage and the probability of successful attack construct urban CIS information interdependent vulnerability assessment model.At lase,Urban CIS multi-interdependent style vulnerability assessment method.This research is different from above two aspects and proposes the concept of multi-interdependent on account of two types or more than two types of interdependent may triggered at the same time when urban CIS suffering social disasters.Taking “geographic-physical” interdependent as one type of multi-interdependent for example,measures the geographic interdependent vulnerability by Euclidean distance and measures the physical interdependent vulnerability by integrity function and loss rate function.The final vulnerability value is the combined value of both to reflecting the system state after multi-interdependent.