A Study On The Evolution Mechanism Of Complex Network Structure In The Yangtze River Delta Urban Agglomeration

Under the dual background of economic globalization and “Internet +”,urban agglomeration has gradually become the core of regional economic growth,which has profound influence on the strength and pattern of China's economic development,as a form of spatial organization in which countries participate in global competition and international division of labor.The rapid flow of human,material,information,technology,capital and other elements in the region has deepened the connection among the cities within the city cluster and between the urban agglomeration and the out-group region,further promoting the economic and social development of the urban agglomeration.The evolution of its spatial organization is moving into the open complex network structure.Therefore,based on reviewing and combing the theories and literatures of the research on the complex network of urban agglomeration,this paper establishes the the theoretical analysis framework of network structure evolution: “complex mechanism of discovering and condensing-the spatial expression of formation mechanism-the test of effect mechanism”.Based on the theory of new economic geography and complex network theory,this paper simulates the network evolution of the urban agglomeration in the Yangtze River Delta during the period of year 1995 to 2014,about 20 years,and finds its evolution and evolution trend,and then puts forward some suggestions to optimize the network of urban agglomeration and promote its economic development.First of all,this paper explores the possible laws of spatial organization of urban agglomeration from the literatures of New Economic Geography,Urban and Regional Economics,and then comprehensively studies the literatures of urban agglomeration networks in recent years.This paper argues that the spatial flow of factors,the perfection of infrastructure network and the promotion of government are the motivations to promote the formation of urban agglomeration networks,and the factor flow is the “source power” of network formation.And in spatial agglomeration and diffusion mechanism and spatial externality mechanism,the network is becoming more and more complex and open.With the improvement of the network level,this high-correlation structure can promote the factors to flow more rapidly and thus has a significant role in promoting the rapid of economic development.Based on this,the evolution mechanism of urban space complex network is analyzed systematically and comprehensively.Secondly,in order to study the spatial evolution of urban agglomeration systematically and comprehensively,this paper then integrates the flow of people,material flow,information flow and capital flow into the improved gravitational model in the framework of this analysis,and establishes the matrix of connections of urban agglomeration within the Yangtze River Delta.The network structure of the urban agglomeration is simulated by UCINET6,and then we get three overall network structural indexes,such as Density,Hierarchy and Efficiency,and three individual network indexes,such as Degree,Betweeness and Closeness.The model is used to analyze the cohesion of the network,and it is found that the characteristics of the network cluster are obvious.At the same time,this paper explains the reasons for the emergence of these features based on the evolution mechanism summarized above.Then,based on the theoretical analysis and the exploration and interpretation of the complex network structure evolution of the Yangtze River Delta,it is found that the overall structural indexes of the complex network is consistent with the overall economic development level of the urban agglomeration,and also the individual structural structure.Based on the analysis of the former mechanism,it is put forward that the whole network structure and the individual network structure of the complex network have significant effect on the economic development level of the urban agglomeration.The overall structure indicators of the network constitute a time series and individual network structure indicators constitute the panel database.The empirical results show that the increase of the Density and the decrease of the Hierarchy and Efficiency are the important driving forces to promote the economic development of the urban agglomeration.In the individual network,the increase of Degree and Closeness and the decrease Betweeness have positive effect on the urban economic development.Finally,based on the research results of the evolution characteristics of complex network structure and the test of network structure effect hypothesis,this paper draws the main conclusions,and draws out several beneficial policy enlightenments based on the current development of Yangtze River Delta.And the shortcomings of this paper,as well as the direction of further research are described.