Modeling And Vulnerability Analysis Of Multilayer Networks For The Urban Public Transportation Systems

Over the past two decades,complex network theory has been applied to explore various transportation systems,such as railroads,shipping,and air transportation systems.Recently,with the rapid development of complex network research,studying urban public transportation systems using complex network theory has become more scientific.Urban public transportation systems are typical complex systems,consisting of several interconnected and coupled transportation networks,such as metro and bus networks.The urban public transportation network represents the core of the urban public transportation system.Therefore,it is essential to fully understand the overall topology and functional characteristics of the urban public transportation network to assist in safety management and sustainable development planning for the urban public transportation system.Furthermore,as the scale of urban public transp ortation systems continues to expand,the line network connections within the transportation system become increasingly complex,and the connections between transportation networks representing different modes of transportation become closer.These questions motivate us to study urban public transportation systems not only from a single-layer network but also from the perspective of multilayer networks.In addition,damage to one transport network in an urban public transport system due to different random or unexpected events can affect its interconnected transport networks.Therefore,studying the vulnerability of different interconnected transportation networks within the urban public transportation system is urgently needed.Currently,scholars worldwide have made significant achievements in researching modeling and vulnerability analysis of urban public transportation systems,but most of them primarily use single-layer network models to study the vulnerability problem of a single transportation network.Most of them adopt several common deliberate attack or random attack strategies.There is no unified study of transportation networks representing different transportation modes within the urban public transportation system.In this paper,we construct a multilayer network model of urban public transportation,focusing on analyzing the vulnerability problems of different types of multilayer networks under traditional attack strategies and the new attack strategies proposed in this paper.We also conduct a vulnerability study for multilayer networks composed of different types of sub-networks under different coupling methods.The main research work is as follows:First,this thesis introduces some classical models of urban public transportation systems and finds that most of them are single-layer network models.However,the urban public transportation system consists of multiple interconnected transportation networks,and damage to any network layer will affect the function of other network layers or even the entire system.Relying solely on single-layer networks,it is impossible to accurately analyze network topology characteristics.Additionally,the network topology characteristics of urban public transportation networks can vary in different urban forms.Therefore,this paper combines the multilayer network approach with the Space L modeling method to establish a multilayer network model of urban public transportation by coupling the metro network and the bus network.This model is used to analyze the influence of the mutual coupling between the metro network and the bus network on the topology and network performance of the multilayer network they form.Then,simulation experiments are conducted to analyze the statistical characteristics of the network topology of urban public transportation multilayer networks from the perspective of the effects of the synergy of different modes of transportation networks,using Qingdao and Chengdu urban public transportation data as examples.The network topology parameters obtained from the experiments are used to find the topology rules of urban public transportation networks that fit the characteristics of different urban forms.Second,based on the characteristics of the established multilayer network model of the urban public transportation network,we propose a new multilayer network node centrality metric: node transfer centrality.We then propose a node attack strategy and a generic attack strategy evaluation function for evaluating the vulnerability of multilayer networks.Simulation experiments are conducted based on Qingdao and Chengdu public transportation data,and vulnerability analysis under different attacks is simulated using the proposed attack strategy,random attack,and traditional intentional attack strategy.We conclude that the proposed attack strategy is more efficient than the traditional attack strategy for different types of multilayer networks.It is confirmed that damage to interlayer nodes in urban public transportation multilayer networks can cause significant damage to the overall network and make the network collapse quickly.In addition,through the comparative analysis of urban public transportation multilayer networks and their sub-network topologies in two different urban forms,Qingdao and Chengdu,it is found that the vulnerability of urban public transportation networks is closely related to the urban forms.The research results provide important reference values for urban public transportation management and public transportation line network planning and optimization.Finally,this thesis investigates the effects of inter-layer coupling patterns and coupling sub-network types on the vulnerability generation of multilayer networks.First,three different types of multilayer networks(BA-BA,WS-WS,BA-WS)are established based on BA network,WS network construction algorithm,and super-adjacency matrix.After that,the network vulnerability of the above three different types of multilayer networks under different coupling modes(negative correlation coupling,positive correlation coupling,and random correlation coupling)is analyzed using the attack strategy established in this paper and the traditional attack strategy.This is used to study the impact of inter-layer coupling patterns and sub-network types on the vulnerability of multilayer networks and then provide a network layout design method to improve the robustness of multilayer networks for urban public transportation.This article proposes corresponding effective solutions for modeling and analyzing the multilayer network of urban public transportation with different city forms using complex network methods,establishing node centrality measurement methods and node attack strategies applicable to multilayer networks,improving inter-layer coupling methods to enhance the robustness of multilayer networks,and establishing network types.