| Innovation network can realize the integration and circulation of differentiated innovation resources in different cities,which is an important driving force to promote regional innovation synergy.The Yangtze River Delta has a cluster of high-tech industrial parks,high-tech enterprises and strong economic development,which is a model of regional development in China.However,with the expansion of the planning scope,the development of cities in the Yangtze River Delta region is becoming more and more different.Under the strategic background of vigorously advocating green innovation,studying the spatial-temporal evolution trend and driving mechanism of urban green innovation network in Yangtze River Delta,and exploring the trend of related development among cities will contribute to the coordinated development of green innovation among cities and promote the process of higher quality integrated development of the Yangtze River Delta.On the basis of the green innovation and innovation network theory,this paper quantifies the green innovation connections among 41 cities in Yangtze River Delta by using the improved gravity model,so as to characterize the green innovation network of cities in Yangtze River Delta.Then,based on Arc GIS 10.8 and Ucinet 6.0 analysis software,social network analysis method is used to analyze the spatial-temporal evolution of this network from overall features,individual features and local features.Finally,the influencing factors of this network evolution are explored by using Quadratic Assignment Procedure analysis method.The results show that green innovation is developing rapidly in all cities,and the green innovation correlation degree of cities in Yangtze River Delta increases year by year.Secondly,cities are becoming more and more interconnected in terms of green innovation,the number of cities at the core of the network increasing by years,and the internal and external connections of urban groups within the network are increasingly close,but a few cities lack cooperation initiative.Thirdly,many factors driving the evolution of the network.The positive effect of the difference of economic development level,the difference of higher education level and the difference of opening to the outside world increases,while the positive effect of geographical proximity decreases.Combined with the research conclusions,the optimization countermeasures are proposed to promote the coordinated development of green innovation in Yangtze River Delta cities from two aspects of optimizing the spatial layout of the associated network and improving the development factor driving strategy. |
