愈发重要的城际要素流动和中国特有的城市行政体系使城市群等区域组织兼具网络化与层级性特征.论文以长三角城市群为例,综合考虑空间连续性、节点连接性和长三角一体化演进态势划分中心层和外围层,借助多层指数随机图模型(multi-level exponential random graph model,ML-ERGM),从企业联系的视角剖析长三角城市网络化与层级构造共存的模式,并从结构层面的基础结构效应与复杂结构效应,以及外生动力层面的城市经济规模、城际物理距离、城际交通可达性、行政边界效应探讨该模式的形成机制.研究发现:①长三角城市群的城际联系网络整体呈现出层级结构,且在城际联系强度上表现出明显的"首府引力效应";②长三角城际联系网络受到结构效应驱动显著,具体表现为中心层闭合、外围层传递和层间扩张的动力机制;③城市经济规模是城际联系网络的重要影响因素,此外,相近的地理距离、便捷的交通网络及位于同一省份均能促进城际企业联系,但三者对不同层级网络的影响存在异质性.研究可为长三角城际联系网络的优化发展提供科学支撑.
Multilevel "city-firm" networks in the Yangtze River Delta and its formation mechanism:A study based on the ML-ERGM model
The increasingly important intercity elements flow and the unique urban administrative system in China lead to regional organizations such as urban agglomerations possessing both networked and hierarchical characteristics.Taking the Yangtze River Delta urban agglomeration as an example,this study comprehensively considered spatial continuity,connectivity,and the evolution of the Yangtze River Delta's integration trend to divide the region into the central layer and the peripheral layer.Using a multi-level exponential random graph model(ML-ERGM),it dissected the coexistence of the network and hierarchical structures in the Yangtze River Delta urban agglomeration network from the perspective of business connections.It also examined the formation mechanism of this pattern from the structural aspects of basic structural effects and complex structural effects,as well as external factors such as urban economic scale,intercity transportation accessibility,intercity physical distance,and administrative boundary effects.The research findings are as follows:1)The intercity connection network of the Yangtze River Delta urban agglomeration exhibits an overall hierarchical structure and shows a noticeable"capital attraction effect"in terms of intercity connection strength.2)The intercity connection network in the Yangtze River Delta is significantly driven by structural effects,with specific dynamics including the closure of the central layer,the transmission in the peripheral layer,and interlayer expansion.3)Urban economic scale is an important influencing factor on the intercity connection network.In addition,a convenient transportation network,close geographical distances,and being located within the same province can all promote intercity business connections,but their effects on different layers of the network are heterogeneous.The results of this research can provide some scientific support for the optimized development of the Yangtze River Delta intercity connection network.
enterprise connectionsnetwork patternhierarchical structuremechanism of influenceML-ERGMYangtze River Delta urban agglomeration
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