Research On Network Structure Of Yangtze River Delta Urban Agglomeration From The Perspective Of Multi-Dimensional Stream Data

With the development of globalization,informatization and networking,the relationship between cities is becoming more and more close,and urban development tends to be networked.The analysis of urban network structure based on “flow data” and “flow space” is becoming a research hotspot of urban system.This paper takes 26 prefecture-level administrative units in the Yangtze River Delta urban agglomeration(YRD)as the research object,and obtains the data of enterprise flow,train flow,information flow and gravitational flow within YRD through the network crawler and statistical yearbook.Then,based on these "flow data",the enterprise network,railway network,information network and gravitational network are constructed respectively,and the urban flow model is used to analyze the urban agglomeration network structure from multiple angles.The purpose of this paper is to study the network structure characteristics of the Yangtze River Delta urban agglomeration in combination with the "flow data" and statistical data network analysis,urban flow model analysis,etc.,and make recommendations for the urban cluster spatial layout planning.The research significance of this paper is that the construction of multi-dimensional network based on "flow data" to analyze urban network structure plays an important role in solving the problems of regional spatial layout optimization,urban functional positioning and resource allocation in the development of urban agglomeration.The main conclusions are as follows:(1)Through the analysis of urban flow model,it is found that the cities in YRD have certain outward-looking capabilities,but there are great differences in the intensity of urban flows,and some cities have clear functional division of labor.Shanghai and Nanjing have the highest level of urban flow intensity and are far ahead of other cities,followed by Hangzhou,Changzhou,Suzhou and other cities,while the urban flow intensity of Anhui Province is significantly lower than other provinces in the Yangtze River Delta.From the perspective of functional division of labor,Shanghai,Nanjing,Hangzhou,Hefei and other cities have a higher level of comprehensive development of tertiary products.The secondary industry is often undertaken by its neighboring sub-cities(Suzhou,Wuxi,Ningbo,Wuhu),and these secondary Although the city has a high outward-looking function in the manufacturing industry,the development level of other industries is low,and the urban functions tend to be specialized.(2)From the weighted centrality of urban nodes,the weighted centrality of YRD based on the four elemental flows shows a trend of weakening from the eastern coastal to the western inland,but the trend and direction of weakness are slightly different.The top-level city nodes of each network are roughly the same,but they differ in the allocation of the primary node and the secondary node.The order-scale analysis shows that the weighted centrality in the enterprise network has the characteristics of concentration in large cities.In the information network,railway network and gravitational network,the distribution of elements in large,medium and small cities is relatively uniform.(3)From the perspective of city classification and functional orientation,YRD presents a pattern of Shanghai and the multi-center cities developing together.The sub-central cities of Hangzhou,Nanjing,Suzhou,Wuxi,Ningbo and Hefei are Shanghai.Spreading its influence to the entire region,these sub-central cities are also an important pillar of Shanghai's participation in global competition.(4)At the inter-city linkage level,the top-level links of the four networks are mostly distributed in the Shanghai-NanjingHangzhou-Ningbo development zone,the Shanghai-Hangzhou-Golden development zone and the coastal development zone.Most of the inter-city associations are distributed along the axis,but there are also hopping associations.From the perspective of hierarchical agglomeration,the elemental flow presents a phenomenon of concentration to the top layer in all four networks.In the first related network,YRD is centered on Shanghai,with the Shanghai-Suzhou dual-core association model as the core,and the main links between Shanghai and Hangzhou,Suzhou,Nanjing and Hefei regional sub-centers and weak central cities.The pattern of general urban agglomerations to regional central cities.Through the analysis of the membership degree and control degree of the main cities in the composite network,it can be found that the administrative division and geographical distance have little influence on the membership degree.The main related objects of the six cities such as Shanghai are mostly the central cities of YRD.Central cities and weak central cities.Administrative divisions and geographical distances have a greater impact on control,and cities with higher control are mostly distributed around regional central cities.(5)Based on the analysis of the hierarchical structure and function of urban nodes in YRD and the analysis of the association pattern of urban agglomerations,the following suggestions are proposed for the spatial layout of YRD: at the urban node level,the Yangtze River Delta should be centered on Shanghai and Nanjing and Hangzhou.,Suzhou,Hefei,Ningbo,Wuxi and other sub-central cities,weak central cities as the support,and jointly promote the coordinated development of the long-term urban agglomeration;in the inter-city linkage level,the Yangtze River Delta should be based on the development axis of Shanghai-Nanjing-Hangzhou-Ningbo,coastal development Axis and ShanghaiHangzhou gold development axis are supplemented to promote the network development of urban agglomerations and rely on the development axis to drive the development of other regions in China.At the level of urban groups,six metropolitan areas centered on Shanghai,Nanjing,Hangzhou,Suzhou,Ningbo and Hefei were built to gradually promote the integrated development of urban agglomerations.