The Research Of Urban Public Ransportaion Networks Topological Vulnerability Analysis And Optimization

With the rapid economic and social development of our country,people's living standards have gradually increased and the use of cars has increased.This has led to serious problems such as severe urban traffic congestion,increased environmental pollution,and shortage of road resources.Urban public transport has long been considered as an effective,environmentally friendly way of solving the deteriorating traffic environment.Nowadays,urbanization is speeding up unceasingly,the state of urban infrastructure investment is increasing every year,the city public transportation as a kind of infrastructure,with the change of the city are also constantly updating.The urban public transport network refers to a large and complex system composed of several bus lines and several bus stations.It can also be regarded as a complex network composed of bus stop sites and the lines connecting these sites.When designers plan and optimize urban public transport,it is necessary to carry out research on their network structure so as to facilitate the scientific decision-making.First of all,this thesis briefly describes the basic concept of complex network,mainly introduces the representation method and topological feature of complex network,and describes the evolution process of two classical complex networks.Taking the urban public transportation network as the research object,the urban public transportation site network and line network are respectively modeled by the L-space method and the R-space method,and the two topologies are converted into matrices that can be stored and recognized by the computer.According to the matrix,the Matlab simulation method of the topological parameters of the urban public transport network is described,including the degree and degree distribution of nodes,the shortest path algorithm,the clustering coefficient and betweenness.Then,TransCAD software is used to store the site and line information of Chongqing public transportation,and the topology matrixing algorithm based on the characteristics of the data of the software is given.Simulation of the algorithm are performed by Matlab.Through the analysis of the calculation results of the network topology parameters,it is found that:(1)The node degree distribution of the public transportation site network in Chongqing obeys the power law distribution,so the site network is a scale-free network;(2)Chongqing's public transportation line network is a small-world network with properties of high clustering and a low-path feature length.Finally,based on the definition of the vulnerability of the public transport network topology,taking the network efficiency as the evaluation index,the vulnerability of the public transport network in Chongqing is analyzed according to two attack methods.And compared with the traditional attack method,the feasibility of the node importance of degree calculation method based on the contribution matrix is verified.concluded:(1)Compared with random attacks,the site network shows more structural vulnerability to intentional attacks,which reflects the characteristics of scale-free networks;(2)Compared with the site network,the structural network vulnerability to the two attack methods is much lower;(3)Considering accuracy and simulation time-consuming,the new method proposed in this thesis is feasible.The new method is used to calculate the importance of nodes,and the network topology optimization recommendations based on the results are given.