Study On Structure And Dynamic Behaviors In Weighted Complex Public Transit Network Based On Passenger Flow

ABSTRACT:Urban public transit network (PTN) is a complex and dynamic system, which is the interaction result between topology and dynamic flow distribution. It is also the evolution result of many factors during the long-term development, such as socio-economic activities, spatial structure, geographical features, cultural customs, etc. As to the complexity of PTN, a new method is provided by the complex network (CN) theory for studying its mechanism and the coupling function in recent years. With more and more research on CN theory at home and abroad, the study on its evolution process and dynamic behavior is paid more close attention. PTN, as a mixture of technic and social network, is a compound complex network with spatiotemporally dynamic complexity.In the study on its complexity, not only the characteristics of topology but also the ones of weighted network loaded with dynamic passenger flow should be studied. However, there is little research on the weighted PTN based on passenger flow at present. In order to explore the PTN’s organizational structure and characteristics, it should be rediscovered in the view of dynamic changes of its impact factors, and the evolutionary process should be simulated. It is significant to research these issues, which has important theoretical and practical value on the optimization PTN in the view of CN theory.In this paper, the PTN loaded with passenger flow is taken as the research object to study its dynamic behaviors and structure characteristics based on CN theory and PTN planning theories. Firstly, the modeling approaches of weighted complex PTN and measures of its structure characteristics are proposed; secondly, based on the systematic characteristics of weighted complex PTN, the evolution mechanisms of these networks are explored, and the evolution models are presented according to different abstract forms of weighted complex PTN. The evolution characteristics of these models are also analyzed with and without capacity constraints. Lastly, the concept of PTN’s stability and related indicators are proposed, and the dynamic behaviors are studied under different faults or attacks with considering flow distribution, which provides theory bases for improving the PTN. Specifically, the main content of this dissertation and innovation are summarized as follows:1. Firstly, models for constructing the weighted complex PTN are proposed. The realistic urban public transit system is abstracted to three kinds of weighted complex network models, which integrates the dynamic flow information into the static topology. The measuring indexes for weighted complex network are introduced systematically and some new ones are proposed based on the characteristics of passenger flow in the network, which enriches the measuring indexes of weighted complex network.2. Secondly, weighted PTN based on passenger flow and topologic network are statistically analyzed and empirically studied. Based on the passenger flow data collected and disposed from Beijing PTN, related theories, such as statistical physics, computer simulation and so on, are used to analyze Beijing bus system, subway system, multimode public transit system and their seven subsystems. The characteristics and functions of PTN’s structure are explored from multi-view and multi-dimension through comparative analysis of the topology and weighted dynamic network.3. Thirdly, the evolution models of weighted PTNs with and without capacity constraints are studied to reproduce the evolution process. Based on the overall consideration of benefits of passengers and transportation companies, and factors of geographical space and spatial position, etc., the evolution models of weighted PTNs for route, station and transfer are built and studied respectively through the methods of theoretical analysis and numerical simulation, and the dynamic behaviors of the flow in the evolution process are also discussed. In addition, through the analysis of flow constraint mechanism in PTN, the structure and characteristics of flow distribution in the evolution models are presented further under the limited capacity of node strength and edge weight, the capacity thresholds are investigated, and the production mechanism of statistical characteristics in realistic weighted PTN is explored.4. Finally, the stability of weighted PTN loaded with passenger flow is analyzed. In this section, the concept of weighted PTN’s stability and its analysis indexes are presented, and the dynamic stability of Beijing PTN is studied by the methods of traffic dynamics and cascading failures respectively. Namely, considering the autonomous and selective behaviors of the flow distribution in the whole network, the dynamic behaviors of PTN are studied based on theory of OD flow distribution; a Coupled Map Lattices model for weighted network is proposed, through the local flow redistribution, the cascading failures caused by the coupling of weighted and topologic network factors, which are with the characteristics of chaos dynamic system, are analyzed.