Research On The Complex Structure Characteristics Of The Spatial Connection Network Of Cargo Transportation

Spatial linkage of freight transportation is one of the important parts of spatial transportation linkage,which can reflect the characteristics of regional economic development level,regional industrial structure and regional differences.And its feature extraction will provide theoretical support for regional industrial restructuring and coordinated regional development to some degree.With the enrichment and improvement of the results of spatial transportation linkage that based on "space of flows",the data including enterprises linkages,traffic,information and funding flows,has widely employed in research for regional differences,spatial structure and spatial evolution of regions.However,firstly,traditional researches of spatial transportation linkage have mainly focused on passenger transportation,and the related achievements about freight transportation are rare and have concentrated on air transportation and specialized commodity transportation,which were limited by the collection and production of transportation linkage data.Secondly,the adjusted gravity model based on the stack of traditional static attribute data was applied to the feature extraction of spatial transportation linkage,it was difficult to accurately reflect the complex interactions among regions.Moreover,previous researches have neglected the impacting of external regional nodes under actual transportation interactions environment.Therefore,on the basis of the OD data output from Yunnan Province Transportation Economic Survey Platform(2014),this paper has carried out the main following research work around the research of structure complexity characteristics of spatial linkage network of freight transportation:(1)Analyze the conception of spatial linkage network of freight transportation and its factor influences,then put forward its procedures of network establishment based on the consideration of the OD data structure affected by external regional spatial linkages.On the basis of the analysis on the related theories such as spatial transportation linkage,central flow,spatial interactive and complex network,the method of feature extraction is proposed from the points of network hierarchical structure and network complexity.At last,the validity of this method is tested and verified by taking Yunnan's road transportation for example.(2)Apply the method of hierarchical structural feature extraction to obtain the hierarchical structural characteristics of spatial linkage network in Yunnan's road transportation.The results show that:spatial polarization effect of inner regions is the major driving force for the formation of spatial differentiation of Yunnan's road transportation;the backbone of spatial linkage in Yunnan's road transportation flow is diamond-shaped and anchored by four major metropolitan areas(Kunming,Yuxi,Honghe and Qujing),and the spatial distribution of its city grade has obvious structural intensity and "center-hinterland";its spatial organization is a complicated process that involve geographical proximity interactions,regional concentration interactions and regional preferential attachment,which the key nodes' control power will be transformed and its function gradually tends to equilibrium with the descending of intercity spatial linkage network hierarchy.(3)From the perspective of economic development level,transportation infrastructure and spatial differentiation of freight resources,the formation mechanism of the hierarchical structural of freight transportation spatial linkage network in Yunnan's road transportation is obtained.The results show that:economic development level has mutual promoted effects for freight transportation spatial linkage,part of which the improved of intensity balance about inner regions of transportation spatial linkage benefit to regional economic development is the narrowing of interval difference;road infrastructure development level has a positive effect on spatial linkage strength of freight transportation,especially the improvement of its transport capacity will strengthen the freight transportation interaction between city nodes;freight resources endowment paly a dominate role in the formation of differentiate characteristics of spatial linkage in Yunnan's road freight transportation,which drives spatial linkages of freight transportation to presents a characteristics of resources endowment orientated.(4)Based on urban and country scale,the method of structure complexity extraction is applied to research the spatial linkage networks of Yunnan's road freight transportation by using corresponding analytical tools of complex network theory.The results show that:urban scale network is undergoing a transition process that from a simple random period to a complex but orderly one and its overall structure has yet emerged;the structure of spatial linkage networks involving urban and country scale also feature small-world network properties,which the external regional spatial linkages will drive the formation of small-world net-work properties through promoting the accessibility and clustering coefficient;different spatial scale networks have different sensitivity in the change of degree,clustering coefficient and strength;under the hostile attack according to the nodes degree and strength of descending,both urban and country scale networks strongly depend on key nodes,and the survivability of urban scale network is superior to country scale network.