Model For Cascading Failures Of The Lifeline System Based On Incidence Degree Of Nodes

Lifeline system is s kind of basic construction which keep the fundamental function of modern city and economy of area, it is the artery and nerve of the city. Lifeline have deep influence on safety and profit of the country. But most lifeline system is a interacting network. The failure mode of lifeline is always the cascading failure. Cascading failure spread through the connection of the network. Because of the connection of network, a small failure of a node can spread the whole network and lead the whole network to breakdown. It is not enough to analysis the failure of network from the static perspective. So it is necessary to establish universality model to analysis the cascading failure of the lifeline. It can provide good decision for government to disaster prevention and mitigation of the lifeline.This article is on the basis of results of this research about lifeline system at home and abroad. This paper analysis the degree of importance of the nodes in the lifeline network from the two aspects of the spatial position of the node in the network structure and its functional role played in the network. This paper proposes an evaluation algorithm of node importance based on variable fuzzy clustering model. This algorithm make clustering results of node important degree through the cyclic iteration of index weight, relative membership degree and cluster center iteration. Comparison with other methods, this algorithm accord with characteristics of Lifeline network and apply to large scale of lifeline. And then using the concept of organization structure to divide the connection of node in lifeline system into direct subordinate, indirect subordinate, positive governing.off-line control and coordinate relation. This paper use adjacent fuzzy scaling method to compute incidence degree of nodes in the different connection forms of nodes. And then mixing the relevance of the whole network to certain the association degree of nodes. Based on the failure spreading dynamics theory on the complex network, combining with the network structure characteristics of the lifeline system,a cascading failure model of the lifeline system is established. Beginning with the incidence degree of nodes to research the influence of connection forms of nodes and network structural characteristics on cascading failure in the lifeline network. The result of the simulation reflect that there is a obvious different scale cascading failure on different connection forms. The thesis studies prove incidence degree of nodes is an important element of cascading failure in the lifeline system. Finally, through numberical simulation of a section of the water supply network to demonstrates the process of this the cascading failure model of lifeline system. The experimental results show that the degree of association between the nodes enlarged cascading failure of lifeline system.This prove that degree of association between the nodes is a important factor to the scale of the disaster.And the simulation results are consistent with the lifeline’s character. It show that the model can effectively simulate the lifeline system cascading failure process and this cascading failure model could provide a theoretical basis for future lifeline protection.