Evolution Process And Dynamic Simulation Of Urban Spatial Evolution In Lanzhou Based On Multi-agent Model

As an complex adaptive system, City is typical and giant, while its subspace system has the same traits, urban spatial evolution is during the process when urban social and economic multi-agent interact with each other, whose has the features of adaptive, complexity and subjectivity. Lanzhou city is the central of the north western regional, which has a important location and the strategic position. At present, it presents a serious state that shortage of urban construction land, increasing population density, urban congestion, environmental pollution and deterioration of living environment, the urban space development has step into a bottleneck that need to be broken immediately, how to improve the urban living environment and achieve a healthy, coordinated and sustainable development of society with limited resources has become the core issue of Lanzhou city and Northwest regions.The article summarizes the relevant information at home and abroad, which accords to the urban spatial evolution of multi-agent theory, by the premise of grasping the transformation of the characteristics of urban space development and expansion, it founds the essence of urban space evolution is the process of high niche land types' embezzlement for lower niche land and surrounded it while introducing land niche theory to analyze the evolution of urban space in Lanzhou city. Based on the above theory, the article builds multi-body model of urban spatial evolution under the overall urban planning scenarios, respectively, as while as studying the interaction between each main city agent and associated coupling with the urban space systems degree of coordination and the development.The results of Grey correlation model and the coordinated development model show:there is close correlation between the main cities agents and urban spatial system,the of coupling degree among agents present downward trend,and so do the two subsystems,overall they are step from the stage into a high coupling running in stage;both the overall coordination and development of urban spatial multi-agent coupled system have an uptrend, and reaches the coordinated development of the whole, while the city agents system lags behind the development of urban space systems.In short, the present situation of Lanzhou city spatial expansion is determined by many factors, the contribution of the four city agents to the urban space changing all the way, for the implementation of urban space efficient, ordered and coordinated development, degree of coordination between the main urban actors should strengthen and improve, the relevant departments should adjustment policies and strategies timely according to the actual urban development; at the same time, we should play the role of market regulation, to stimulate the city's adaptive force and self-adjustment capability. Though the double effects of macroeconomic policies and micro adjustment, the development of Lanzhou city can be expected to a harmonious and efficient road of sustainable development.