Complexity Theory And Its Applications In The Study Of Urban Systems

Urban system, which is made up of nature, society and economy is a compound system based on urban ingredients. Multi-Level, high-dimension, multi-scale, non-linearity and self-organization are its features. Complex System Theory is the development of Modern System Theory and Non-linear Theory. Urban system is usually aptitude, adaptive and abstract. As having the attributes of Artificial Life, AL became the main method to research the Complexity of systems. The primary motive of this paper is to solve problems in urban system. Artificial Life is the masterstroke. Researches on urban system by AL include theories, methods and applications. The contents of this paper are: 1.Urban System is introduced. The complexity of urban system is revealed. Four research fields of urban system are put forwarded. The progresses and the current status of urban system are reviewed. Complexity and dynamic of urban system are considered to be the frontier of urban system research. The background of CAS is summarized. Artificial Life has been the main research objective of complexity. The applications of complexity theory to urban system are summarized. 2.Methods about Complexity Artificial Life are analyzed in this paper. A frame system is proposed which includes Network Dynamic, Multi-agent and Complexity Adaptive System. It is based on the study of the variations about rules and structure in the dynamic process of urban evolution. The theories, application and features of the method above are summarized in the paper. 3.Summarize the application of Cellular Automata to the research of urban system. It includes: simulation of complexity of urban space, research on urban problems and model building of urban system. Based on the research into urban influence regions theory, the application of Cellular Automata to the building of weighted Vonoroi diagram is provided. The algorithm for generating urban influence regions is put forward. The algorithm is used to study 10 districts of Shaanxi Province. 4.The Genetic Algorithm and the schema theorem are introduced in the paper. The applications of GA to the research on urban system are presented. Urban district dispose theory is presented. The general algorithm based on GA for finding the optimum location for urban firehouse is presented in this paper. The algorithm is applied to determine the firehouse location and the responsible area of Xi'an. The empirical revealed that it's a general algorithm that could be used to solve problems concerning firehouse location distribution. 5.Particle Swarm Optimization is introduced. GA-PSO, which is based on GA & PSO, is presented. GA programming algorithm is put forwarded. The expression of solution is changed from tree-structure to linear list. The traffic flow of Xi'an is predicted by use of GA-PSO, GA programming and GP. The empirical evidence indicates: the convergence performance of GA-PSO is better than GA programming, and GA programming is better than GP. 6.The principles of Immune system, the models & algorithms derived from Artificial Immune System are introduced in this paper. The features of Artificial Immune System are presented. The applications of AIS in urban evolvement models, and map identify are summarized and prospected. The principles Ant Colony Optimization are introduced in this paper. The applications of ACO to urban research are summarized. 7.Theory and models of Complex Adaptive System is generally introduced in this paper. The features of CAS are summarized. The process of model building of CAS is presented. The requirement-service model based on Complex Adaptive System theory and Central Place Theory is put forwarded. The generating process of urban system is visible through computer simulation.