航空网络嵌入对中国城市知识生产的影响研究

随着城市间网络联系的快速发展和技术创新对团队依赖性的日益增强，城市的知识生产也将越来越多的受到网络外部效应的影响。基于航空客运直飞航班数据构建城市网络，利用专利申请量测度城市的知识生产规模，研究了航空网络嵌入对中国城市知识生产的影响及其异质性特征。结果发现：航空网络的知识管道效应已经成为影响城市知识生产的重要因素，拥有更高网络地位、能够利用更多网络资源的城市具有更高的知识生产效率；航空网络嵌入的知识产出效应呈现递减的边际影响，知识产出水平越高的城市从网络链接中得到的收益越小；知识来源较多、创新较为活跃的经济部门将从网络联系中获得更高的收益，而技术问题可分解性较强、技术处于成熟阶段的部门受益较少；由于知识产出规模、主导产业特征的差异，中国东部地区城市创新活动从航空网络嵌入中获得的收益明显小于中西部地区城市。

Impact of Airline Network Embedding on Knowledge Production of Cities in China

Based on a comprehensive theoretic perspective of network externalities and economics of innovation, the main sources of the knowledge pipeline effects of air traffic network are examined, and the influence mechanisms of air transport on urban knowledge production are analyzed. Information of direct flights between cities in 2019 is used to construct the urban network, and the number of patent applications is used to measure the level of urban knowledge production. Then the impacts of network embedding on knowledge production are quantitatively tested by a combination of multiple linear regressions, quantile regressions and geographically weighted models. Two conclusions are drawn. 1) The knowledge pipeline effect of air transport network has become an important factor influencing urban knowledge innovation. On the one hand, in the “space of flows”, the air network acts as a bridge to link diverse knowledge production systems that are geographically dispersed, promoting the flow, matching and combination of complementary knowledge. As a result, the cities with higher ability to use network resources exhibit higher knowledge production efficiency. On the other hand, cities that are the first to be linked by air transport are usually innovation hotspots, which make the knowledge output effect of airline network present a diminishing marginal impact. As a result, the higher the level of knowledge output, the less the city will benefit from the network linkages. 2) The effect of airline network embedding on knowledge output presents sector heterogeneity and spatial heterogeneity. From the perspective of the sector heterogeneity of network effects, sectors with more knowledge sources and more active innovation, such as H and C in the International Patent Classification (IPC) system, will obtain higher benefits from network connections, while sectors whose technical issues are decomposable or technologies are in mature stage, such as F and D in the IPC system, will benefit less. From the perspective of the spatial heterogeneity, due to differences in the scale of knowledge output and the characteristics of leading industries, cities in the eastern China benefit significantly less than those in the central and western China. The results of this article have clear policy implications. The policy makers should improve the layout of airlines to fully release the knowledge pipeline effects of air transport network on urban knowledge innovation, and implement differentiated innovation policies to promote the division and cooperation of different urban knowledge production systems across a larger geographical scope.