| Along with the rapid development and deepening of globalization,urbanization and informatization,the flow of various factors among cities has become more and more frequent.By adhering to various networks of relationships,cities collect various development resources,and continuously enhance their vitality and competitiveness.As a world-wide country with a vast territory,a large population and a rapid development,China has various types of city connections and complex structures.Urban regional research needs to combine more urban-based networks with urban-level systems.Traditional urban spatial connection research mainly focuses on single element flow such as traffic flow,economic flow and information flow.The comprehensive and comparative study of various element flows is relatively rare.The measurement of urban spatial connection based on multiple perspectives can comprehensively reflect the complex characteristics of urban linkage.The complex network analysis can better reflect the characteristics of urban network structure.The study of types and numbers of elements that cities adhere to can help us better understand the cities' comprehensive competitiveness.Therefore,this study is supported by spatial interaction theory,central land theory,flow space theory and urban network theory.It draws on the ideas of predecessors on building urban contact networks,based on flight schedules,train schedules,city statistical yearbooks,Baidu search Index,Baidu map service and other data,building a Chinese city network based on air traffic flow,railway traffic flow,foreign economic flow,Baidu information flow.It also calculates the strength of the connection between two cities in China's 291 cities and analyzes the characteristics of China's urban contact network by complex networks analysis method,drawing the following conclusions:(1)The urban connection network based on aviation links has the morphological characteristics of “diamond structure” and constructs the skeleton of the Chinese urban network.The urban spatial connection network based on railway links shows a supporting axis along the transportation infrastructure and constitutes the Chinese urban network.Air traffic flow has a strong "space-time compression effect",and railway traffic flow has a certain "along effect." Urban networks based on economic linkages are constrained by the interaction of urban hierarchy and spatial distance.The urban network based on information connection has the characteristics of “hyperplane”,which is less constrained by the space of the place and has obvious characteristics of flow space.In general,prefecture-level cities across the country show varying degrees of spatial connection strength and different types of spatial linkages.National urban networks have distinct hierarchical characteristics,and several regional urban networks have been formed at different scales.(2)The number of railway node cities is more than that of aviation node cities,and the railway contact network is denser than the aviation contact network.The urban aviation contact network and the railway contact network have larger clustering coefficients and smaller average path lengths,showing better network connectivity and stronger agglomeration,reflecting the feature of a certain small world.Among the four urban networks,a small number of cities such as Beijing,Shanghai,Shenzhen,and Guangzhou have strong centrality,and are centrally located in the urban network.Most cities are in a weak city position in the urban network and are under the control of the central city.Compared with the air traffic network structure with the immature community development,the blurred community boundaries and the unclear spatial distribution characteristics,it has strong distance sensitivity and dependence on transportation infrastructure.The railway transportation network influenced by the passenger flow organization mode and administrative boundaries exhibits strong geospatial dependence,community structural characteristics and regional functional groups.Compared with economic linkage networks that are characterized by urban functions and distance attenuation,which are characterized by obvious community structure characteristics,are subject to urban hierarchy and multidimensional proximity.The multi-impact information contact network has relatively complex community structure characteristics;the cumulative distribution of Chinese urban networks shows that the Chinese urban network is in a transition from a random network to a scale-free network,with multi-scale signs and multi-fractal structures,and the city follows the principle of survival “the optimal connection”,the flow of four elements between cities has the dual characteristics of horizontal flow and vertical flow.(3)Air passenger flow organization and railway passenger flow organization have sensitivity differences between distance attenuation and administrative boundary constraints.The different hierarchical structure characteristics reflected by urban aviation links and urban railway links reflect different technical and economic characteristics and passenger flow organization management system.The spatial organization of economic flow and information flow has sensitivity differences to urban energy level and multi-dimensional proximity.Urban economic contact network reflects multi-scale spatial organizational structure patterns like "single core","dual core","multi-core",etc.The association analysis of urban node attributes reflects that cities from different perspectives have different scales.Urban linkage competitiveness is an important component of urban comprehensive competitiveness.Urban strength under different linkage perspectives has different regression fitting relationships.The results of association analysis of urban contact energy levels show that the differences of different types of cities reflect the characteristics of transportation modes and the impact of realistic distance.This research has important theoretical practice and technical method significance,mainly lies in:(1)Theoretical and practical significance.Based on the central theory and urban network theory,this paper combines spatial connection with geographic network,embodies the relationship change of urban system research,and proposes the general analysis ideas and research framework of urban spatial connection measurement and urban network feature identification.Based on the perspective of multi-relationship between economic flow,traffic flow and information flow,it described the strength and direction of the relationship between cities,made the basic judgment of regional spatial network structure,and evaluated the competitiveness of cities in urban system from the perspective of the types and quantity of urban adhesion factors.It has important theoretical and practical significance for the study of urban and regional development.(2)The significance of technical methods.The quantitative urban and regional research based on spatial interaction theory model and "big data big model" is carried out in this paper,focusing on large-scale data-driven,several data aggregation rules,integration of multiple technical methods,and analysis of urban networks using complex network analysis techniques.The paper carried out the hypothesis testing of relational data by node attributes and node connections and propose a more reasonable technical route for urban linkage and urban network research. |
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