City network is an important perspective to study cities and regions. In recent years, a large number of studies on city networks involving China have emerged. For the one hand, the case study of China has always been attracting the attention of scholars all over the world for the past decades, and remarkable development has been achieved in city network research on China. For the other hand, while the number of publications is growing really fast, some limitations and challenges of this research has also appeared. Therefore, a systematic review to this large body of literature is needed at present. This article summarizes and reviews the progress of city network research on China from four aspects: 1) Data and methods used in city network research on China; 2) The major findings of this research, including network patterns and formation mechanism on different spatial scales; 3) The main contributions of this field; 4) Some limitations of current studies and the prospect for future research. The findings of this article are provided as follows. City network research on China utilizes various data and methods to construct networks, while Social Network Analysis and Complex Network Analysis are applied to the description of city networks. Major findings of city network research on China covers three spatial scales: global scale, national scale and regional scale, which have revealed the characteristics and formation mechanism of city network on China under different spatial scales. Mainly contributions of city network research on China include: 1) Multi-scale studies on city networks of Chinese cities are important inspirations for city network research worldwide; 2) Avoiding Western Centralism views on studying globalization and making up for the major defects in the research of world cities; 3) Using some original perspectives and data to depict inter-city relations, which has promoted the development of world city network research; 4) Bringing the network logic to the studies of Chinese cities as well as helping promote the academic development of urban geography and economic geography in China. Main limitations and challenges include: 1) A large number of empirical studies dedicate to describe and explain the network structure, paying less attention to theoretical innovations; 2) The data sources and network construction methods used are increasingly convergence, leaving no much room for related innovations in future work. Accordingly, we propose that city network research on China should actively expand the research perspective. Deepening the mechanism research and theoretical innovation should also be highlighted. And strengthening policy studying of city networks on China can benefit the further development of this field, which is almost neglected in current stage.

现有研究采用多元化的数据和方法构建并分析城市网络,揭示不同空间尺度下中国城市网络的特征和形成机制。中国城市网络研究的贡献体现在以下4个方面：① 以中国为背景的多尺度城市网络分析对世界城市网络研究具有重要启发;② 强调国家和区域背景,避免了欧美中心论的全球化观点;③ 采用新颖的数据和视角构建城市网络,推动了世界城市网络研究的进展;④ 增强了国内地理学界对城市网络和外部联系视角的重视,促进了学科发展。同时,当前中国城市网络研究也面临挑战。一方面,大量研究主要着力于城市网络的可视化和描述性分析,机制分析薄弱,理论创新不足;另一方面,当前研究的数据和方法日益趋同,迫切需要新的研究视角。未来需要加强方法和理论创新,深化机制和影响研究,并提高研究的政策相关性。

Based on the data of Chinese enterprises that entered the Fortune 500 list in 2015, this paper uses the eclectic model to construct the inter-city association network. Using the network analysis method, the spatial connection characteristics of 311 inter-city networks at prefecture level and above and 20 urban agglomerations networks in China are examined respectively. The research found that: (1) The overall connectivity of urban network is poor, the centripetal concentration is strong, and the network is not complete. The urban network connection shows a strong tendency of political center cities directivity, coastal cities directivity as well as resource-based cities directivity. The external economic dependence of each node city in the urban network is high, and the urban network structure has obvious flattening characteristics. The network of urban agglomerations is characterized by decentralization of power, differentiation of status and dependence on external connections. (2) The boundary effect of provinces, urban agglomerations and urban agglomerations clubs in the urban network is significant. The network evolution process is influenced by the provincial administrative district economy, the urban agglomerations economy and the urban agglomerations club economy. The size and number of central cities in the region and its surrounding areas have an impact on the provincial administrative district economy, the city agglomerations economy and the urban agglomerations club economy. (3) The function of cities is obviously divided in a multi-scale network. The large cities and regional central cities have a complete and more balanced function system than the small and medium-sized cities do. The radiation effect of three major urban agglomerations in coastal China is significant, while the dominant function of other urban agglomerations needs to be strengthened. (4) The cross-scale regional functional interaction effect of cities (clusters) is significant. The radiation-driven function of cities (clusters) is positively related to their self-agglomeration capabilities. This study provides support for the understanding of urban network model expansion and the spatial relation of urban network in China.

基于2015年世界财富500强中的102家中国企业数据,根据企业组织特征构建了反映企业—城市间关联的折衷网络模型,借助网络分析等多种方法分析了中国地级城市间和典型城市群之间的网络联系。研究发现：① 城市网络总体连通性较差、向心集中性强,发育不够完备;城市网络连接具有明显的行政中心指向、沿海指向和资源指向;网络节点城市对外经济依赖度高,网络结构扁平特征明显。城市群网络存在权力分散、地位分化和外部联系依赖特征。② 城市网络中省域、城市群和俱乐部边界效应明显,区域内外的中心城市规模和数量对省域行政区经济、城市群经济和俱乐部经济的发展产生影响。③ 城市在多尺度网络中的功能分化明显,大城市和区域型中心城市比中小城市拥有更加完备和均衡的功能体系。沿海三大城市群的辐射带动作用明显,其他城市群的优势功能有待突出。④ 城市（群）跨尺度区域功能互动效应显著,城市（群）的自我经济集聚能力与城市（群）的对外辐射带动功能之间存在密切的正向关系。研究为城市网络模型拓展及理解中国城市网络空间联系特征提供了支撑。

As an important property of city, city functions in different periods differ in forms, intensity and spatial characteristics from the preindustrial age to the postindustrial age. City function experienced from a single and simple function to various, messy and homogeneous functions and then to the diversified different and complementary networked evolution process. This article tries to open a new view angle of city linkage research based on the evolution of city function by constructing an analytical structure of city functional network. The city functional network in the postindustrial period consists of three components of function elements, linkage channel and role carrier. On the basis of diverse, different and complementary city function and through the tangible or intangible linkage channel and taking the entity or virtual spatial flow as the role carrier, forms spatial network structure of city functional network was formed. Based on the evolution process of city function and the concept and connotation of city function network, the article took the evolution of city function network in the Zhujiang River Delta as an example, and reconstructed the history and space features of city linkage in the region and finally constructed a new analytical perspective of city function network on city linkage researches.

以城市功能的演进历程为城市联系研究的新视角,构建了城市联系的城市功能网络分析框架。其中,城市功能网络由功能要素、联系通道和作用载体三部分组成,是城市功能在多元、差异和互补的基础上通过有形或无形的联系通道,以实体或虚拟的空间"流"为作用载体形成的城市功能空间网络化结构。基于城市功能网络的概念内涵,以珠江三角洲城市功能网络的演化历程为实例,演示了该地区城市联系的演化历程和空间特征,探索了城市联系的城市功能网络分析视角。

At present, there is a consistency that the focus of urban system research has shifted from the hierarchical to network paradigm. Based on an extensive review of existing studies, this paper investigates the shift of paradigm of China's urban system research since the 1980s, and discusses the development situation, main problems, and key topics of related research on urban network. The results show that: (1) After 2010, the amount of literature about urban network has increased dramatically and become the mainstream of urban system research, while the number of studies on the hierarchy system decreased. And the existing studies mainly focus on the urban system at national level and in the Yangtze River Delta. (2) The attribute data to a certain extent compensate for the lack of data in the early urban network research. Meanwhile, although the gravity model was widely used in these studies, its suitability is gradually decreasing. (3) In contrast, the relationship data have attracted scholars' attention, which is mainly applied to the urban system research from three perspectives: enterprise organization, traffic flow and information flow. However, due to the limitations of different perspectives, a comprehensive research on multiple perspectives has gradually become imperative. (4) The identification analysis has been the dominant theme of urban network research. Visualization analysis and design for urban system is mainly supported by directed unprivileged networks and undirected weighted networks. (5) Five important aspects of urban network research in future include adjusting the research framework of national urban network, examining the physical connections between cities directly without traffic data, measuring the horizontal linkages between the outside enterprises, analyzing and visualizing the directed weighted network research, and intensifying the geospatial characteristics of urban network research.

当前,学者普遍认同城市体系研究的重心从等级范式向网络范式转向。在大量的文献梳理基础上,阐述20世纪80年代以来中国城市体系研究范式的转向过程,并进一步梳理中国城市网络研究的进展、问题与关注重点。结果表明：2010年之后,网络成为中国城市体系研究的主流范式,等级体系文献数量呈波动递减趋势,全国和长三角成为热点关注区域;属性数据一定程度上弥补了早期城市网络研究中数据匮乏的状况,关系数据应成为未来研究的侧重点;不同研究视角及其所应用的数据存在着一定的局限性,多元视角的综合研究成为趋势。在此基础上,提出城市网络研究未来可能的突破点,包括：调整国家城市网络的研究框架、超越交通数据直接考察城市间的实体联系、测度企业外部的横向联系、有向加权网络分析和可视化、增加研究中的地理“意味”等。

Globalization and informatization promote the evolution of urban spatial organization from a hierarchical structure mode to a network structure mode, forming a complex network system. This study considers the coupling of “space of flows” and “spaces of places” as the core and “embeddedness” as the link and a relevant theoretical basis; then we construct a conceptual model of urban networks and explore the internal logic of enterprise networks and city networks. Using the interlocking-affiliate network model and data from China’s top 500 listed companies, this study constructs a directed multi-valued relational matrix between cities in western China from 2005 to 2015. Using social network analysis and the multiple regression of quadratic assignment program model (MRQAP), this study adopts a “top-down” research perspective to analyze the spatio-temporal evolution and growth mechanism of the city network in western China from three nested spatial scales: large regions, intercity agglomerations, and intracity agglomerations. The results show the following: (1) Under the large regional scale, the city network has good symmetry, obvious characteristics of hierarchical diffusion, neighborhood diffusion, and cross-administrative regional connection, presenting the “core-periphery” structural pattern. (2) The network of intercity agglomerations has the characteristics of centralization, stratification, and geographical proximity. (3) The internal network of each urban agglomeration presents a variety of network structure modes, such as dual-core, single-core, and multicore modes. (4) Administrative subordination and economic system proximity have a significant positive impact on the city network in western China. The differences in internet convenience, investment in science and technology, average time distance, and economic development have negative effects on the growth and development of city networks. (5) The preferential attachment is the internal driving force of the city network development.

As traffic flow reflects the socio-economic relations between cities, it is widely applied as a key factor in studies on city networks. Based on the inter-city railway and air passenger flow in 2010, this article made a comparison of the spatial structure and passenger flow organization of inter-city networks from the perspective of railway and air passenger flow, in terms of node, linkage, and community. The results are as follows: (1) Both city networks based on railway and air passenger flow present a hierarchical structure with Beijing, Shanghai and Guangzhou being the top three, while the nodes in the lower classes of two networks are different. (2) The spatial structure of linkages between cities based on railway passenger flow displays strong neighborhood effect. In contrast, the cities' own characteristics play a dominant role in the organization of air passenger flow. (3) Most of the dominant railway passenger flow is directed to the capital city in each province, forming several disperse regional systems separated by the provincial boundaries. In terms of air passenger flow, the regional systems are integrated by vertical linkages between them. (4) Although the community structure is not obvious from the perspective of air passenger flow, there are seven communities of significant geographical characteristics being detected in the railway network. The main differences between two networks are attributed to the management systems and technical characteristics of the modes of transportation.

交通流是反映城市间社会经济联系的重要表征,被广泛应用于城市网络研究中。基于2010年中国城际铁路与航空客流OD数据,本文从城市节点、流量、子网络视角对中国城市网络的结构特征与组织模式进行了比较研究,发现：① 铁路与航空流视角下的中国城市网络均呈现出以北上广为顶层节点的空间等级结构体系,但除顶层结构外两种网络结构差异较大。② 城市网络体系中的铁路流联系表现出空间邻近性特征,而航空流联系则主要受到城市节点的规模大小与职能属性的影响。③ 铁路流的首位联系受省级行政区划的制约,航空流的首位联系空间跨度大,形成了若干具有垂直层间联系的地域子系统。④ 铁路网络拥有具有显著地域特征的7个子网络,而航空网络中则不存在明显的子网络。技术经济特征与管理体制是造成铁路与航空两种网络特征差异的主要原因。

The change of urban regional spatial structure influenced by information technology has become a hotspot of research at home and abroad. This study tries to analyze China's city network characteristics from the social network space perspective by using Sina microblog as an example. The result shows that China's city network based on the micro-blog social space has a clear hierarchical structure and level distinction. Firstly, the result shows the existence of regional characteristics, performance as a visible regional development pattern which contains "Three Main-regions and Four Sub-regions" according to the analysis of the level distinction in the city network and the connection rate between cities. Specifically speaking, the three main regions contain the Beijing-Tianjin-Hebei region represented by Beijing, Pearl River Delta region represented by Guangzhou and Shenzhen, and the Yangtze River Delta region represented by Shanghai, Hangzhou and Nanjing. The four sub-regions contain Chengdu-Chongqing region, west coast of the Taiwan Straits region represented by Fuzhou and Xiamen, Wuhan region represented by Wuhan and Changsha, Northeast China represented by Shenyang, Harbin and Changchun. Secondly, the result shows there is a significant difference of the network links among Eastern, Central and Western China. Links within Eastern China and the links between Eastern, Central and Western China constitute almost all of the current network systems. It is also found that the high-level cities have an absolute dominance in the city network pattern, and that Beijing is the contact center in China's city network, with an overwhelming advantage. Shanghai, Guangzhou and Shenzhen are the sub-contact centers in the China's city nework.

信息技术影响下的城市区域空间结构变化得到了国内外学者的关注。本文以新浪微博为例, 从网络社会空间的角度入手, 对中国城市网络发展特征进行了研究。研究表明:微博社会空间视角下的中国城市网络存在着明显的等级关系与层级区分, 城市的网络连接度与城市等级表现出了相对一致性。根据城市网络层级与网络联系强度, 东部、中部、西部3 大区域板块的网络联系差异明显, 东部地区内部的联系, 以及东部与中部地区和西部地区的联系几乎构成当前网络体系中的全部。城市网络呈现出分层集聚现象, 具体表现为“三大四小”发展格局, 即京津冀区域、珠三角区域、长三角区域、成渝地区、海西地区、武汉地区、东北地区。高等级城市在整个城市网络中处于绝对支配地位, 北京以突出的优势成为全国性的网络联系中心, 而上海、广州、深圳则成为全国性的网络联系副中心。

The interactive relationships between cities in the knowledge economy era have attracted much attention. Researchers have applied a range of methods to explore intercity innovative relationships and associated network characteristics. It nevertheless remains unclear just how intercity innovative relationships can be theoretically constructed based on knowledge flow space and how further scientific simulation methods can be designed. Research questions in this area have rarely been explored in detail, an issue which has inevitably placed obstacles on further exploration. A framework for the theoretical construction of intercity innovative relationships is presented in this study; the basis for this research is that an intercity innovation network is essentially a 'soft network', distinct from a 'hard network'. These interconnections are founded on a subjective relationship construction process and therefore necessitate scale transformation from 'point-point' connections between innovative subjects in different cities with respect to 'city-city' interactions. At the same time, this transformation process is prone to exaggerations and deviations from objective intercity innovative relationships and therefore exerts considerable influence on the accuracy of results such that constructions must be entirely theoretical. Four construction methods for intercity innovative relationships and network simulation are summarized in this study, including an intercity undirected network based on cross-city co-operations between scientific and technological achievements, an intercity directed network based on the cross-city transfer of scientific and technological achievements, an intercity innovation network based on the cross-city flow of high-end talents, and an intercity innovation network based on the multi-city distribution of innovative enterprises and institutions. Simulation tests were then undertaken using relevant data to reflect aspects of these relationships. The results of this analysis are conducive to further exploration of global and regional innovative spatial patterns from the perspective of urban geography and intercity relationships and provide a theoretical and methodological foundation for further research on intercity innovation networks.

知识经济时代城市间的创新关系是新时代城市间相互作用关系的新内涵,研究者尝试采用各种方法探索城市间创新关系及其网络特征。然而,如何从理论上建构知识流动空间的城市间创新关系?如何设计更加合理的城市间创新网络模拟方法?这些问题却少有专门探讨。基于相关研究,本文提出了城市间创新关系构建的理论框架,认为城市间创新网络本质上是区别于“硬网络”的“软网络”,是一种主观的关系建构过程,需要经过异城创新主体间的点—点关系向城—城之间关系的尺度转换,这一转换过程容易发生夸大或偏离城市间客观存在的创新关系,对结果的精确度产生很大影响,应对关系建构给予充分理论论证;本文论述了4种城市间创新关系建构和网络模拟方法,包括科技成果异城合作的城市间无向网络构建方法、科技成果转让转移的城市间有向网络构建方法、高端人才跨城移动的城市间创新网络建构方法和创新企业机构多城分布的城市间创新网络建构方法,并运用相关数据进行了模拟试验与结果展示,来反映城市间创新关系的不同方面。本研究有助于推动从城市地理学视角和城市关系的维度探讨全球/区域的创新空间格局,为城市间创新网络研究提供理论和方法支撑。

In recent years, urban networks have become a focus of research in geography, urban studies, and other related disciplines. While previous research has examined the urban networks in China from different perspectives, the networks generated by cultural industries have remained a largely unexplored area. This article aims to fill this gap by presenting a comprehensive analysis of the spatial structures of the cultural industry-generated urban networks in China's mainland and compares the disparities between these networks and the urban networks created by other types of economic activities. Data of the headquarter-affiliation connections of 230 NEEQ (National Equities Exchange and Quotations)-listed cultural firms in 2017 were collected and analyzed using social network analysis method. In addition, the article also explores the economic and social factors that shape the formation of the spatial patterns of China's cultural industry urban networks drawing on the method of multiple linear regression (MLR). The outcomes reveal that: First, shaped by both market mechanisms and the interventions of local governments, the distribution of the NEEQ-listed cultural firms demonstrates a geographically dispersive, but quantitatively concentrated pattern in China. The spatial structure of the cultural industry urban networks is highly uneven, with most inter-city connections concentrated in the eastern part of the country. The cultural industry urban networks do not exhibit the typical diamond-shaped structure that has been observed in many other urban networks in China. Second, the core nodes of the cultural industry urban networks are mainly economically advanced metropolises in the eastern and central areas, as well as a few minor cities that possess some special local assets, including large film and television studios, unque natural or humanistic environment, and preferential tax policies. Most cities are receivers instead of exporters of cultural industry functions. Third, the expansion of the cultural industry urban networks is mainly between the core nodes of different hierarchies instead of between geographically proximate cities. The contribution of local (intra-urban) networks to the formation of intra-firm relationships of cultural industries is weaker than that of trans-local networks, which indicates that, compared with the advantages of geographical proximity, the complementarity of market or resources is the primary factor considered by cultural firms during their expansion. Fourth, the urban networks of different subsets of cultural industries have rather diverse spatial structures, which reflect the varied market demands and development conditions of different cultural industry activities. Fifth, according to the outcome of MLR analysis, the function of local governments and urban industrial structure are two important factors that shape the location strategy of cultural firms and the pattern of cultural industry urban networks in China, whereas the impacts of other economic and social factors are not significant. The article enriches our understanding of the spatial organization of cultural industries and the diversity of modern urban networks. It also sheds light on cultural industry development policies in the Chinese context.

论文通过对230家“新三板”文化产业挂牌企业总部—分支机构关联数据的收集、整理和分析,对文化产业视角下中国城市网络的空间结构特征进行研究,比较文化产业城市网络与其他类型城市网络的差异性,并探索影响文化产业城市网络空间格局的经济社会因素。结果表明：① 中国文化产业挂牌企业地理分布呈现出地域分散但数量集中的特点,城市网络空间分布高度不均衡,并未表现出常见的“菱形结构”;② 网络核心节点以东中部发达城市以及少数具有特殊资源的城市为主,多数城市的对外输出能力有限;③ 城市网络扩散以核心节点城市间的等级扩散为主,邻近城市间的扩散效应不明显,同时本地网络(即城市内部网络)对文化企业组织结构的贡献度低于跨地域网络;④ 不同类型文化产业在网络结构上表现出较为明显的差异,反映其市场需求和发展条件的不同;⑤ 地方政府作用和城市产业结构是影响中国文化产业企业布局和网络格局形成的重要因素,其他社会经济因素的作用则较为不明显,反映出中国文化产业的独特性。

The ability of cities to operate in global networks is usually measured according to their central position within multinational firm linkages. These measures are often used at the interurban level and neglect the intraurban processes of multiplier effects. The present study demonstrates that this affects the measurement of city centrality in business networks. Intraurban capabilities of interaction are considered in the measurement of interurban indices. The study is based on hypothetical networks at a micro level between long-range links and it mobilises processes as agglomeration economies, social capital developments and transaction costs. These processes at the intraurban level strengthen the efficiency of interurban linkages. It is suggested that the indices used to measure city centrality should include these local effects. Applied to a small sample of six firm networks, the methodology shows advantages for emerging large metropolises, but insufficient local effects for specialised clusters. The multilevel approach offers improved perspectives for the comparison of city centralities.

As an “industry”, the time of Chinese film is short. So research about Chinese film industry is rare and far behind the actual development of practice. Foreign economic geography scholars research film industry mainly from industrial cluster as the core of the local network and value chain, global production network as the core of the global network. In the theoretical aspect, the research from the network perspective on the film industry is similar with manufacturing, high-tech industries and so on. They pay more attention to the production of whole process. The research about the distribution and exhibition of film industry is less. From the empirical perspective, the case studies are almost about the developed countries. However, the social, cultural and institutional factors have great influence on the development of the network. Therefore, research of the film industry in the developing countries is urgently needed to be carried out.

我国电影以“产业”形态发展的时间较短，学者们对电影产业的研究较为匮乏。国外经济地理学者关于电影产业的研究主要从以产业集群为核心的地方网络和价值链、全球生产网络为核心的全球网络视角出发。理论层面，从网络视角出发对电影产业的研究与制造业、高技术产业等一致，核心关注点是生产这一单一环节的网络构建、发展、空间演化特征等，对发行、放映等其他价值链环节的系统性研究不足。案例层面，主要集中在欧美发达国家的电影产业，然而社会、文化和制度因素对网络发展影响较大，因此以我国为代表的发展中国家电影产业的网络研究亟待展开。

在全球化、信息化背景下,城市之间的竞争已经不再局限于单体城市本身的规模属性,而是越来越取决于城市参与分工协作的地位以及多尺度空间的功能联系,尤其表现在城市网络化、集群化的竞合态势,而城市群已经成为该背景下具有全球意义的空间组合模式。在系统梳理了中西方城市功能地域概念的内在关联基础上,论文认为,中国的城市群概念具有尺度伸缩性,与西方的巨型城市区域、巨型都市区和巨型区域概念是最为接近的。在空间内涵上看,城市群是2个以上城市体系组成的巨型城市地域,是兼具形态连续性和功能内聚力的城市系统,是全球化与本地化显著交互作用的大型经济单元,是当今时代城市与区域分工协作的一种尺度修复。基于此,城市群发育的基本条件主要包括良好的资源环境综合承载能力、大都市区与多个城市系统、地理空间上的邻近性与紧凑性、发达和完善的基础设施网络、深入协调的功能分工与经济联系以及相对一致的社会网络和文化认同。未来,中国城市群研究应更加兼顾形态和功能维度的统一,尤其注重从关系地理与城市网络视角探索城市群的空间集聚效应及其演化规律。

With the rapid development of ICTs and big data technology, various "flow" data have become easier to be obtained such as population flows, information flows and capital flows. These data are key material to build the production network, social network, urban network and other types of network, which are becoming very important research subjects of geographical sciences and enrich the research content of this field. So far, researches on the networks in geography are still in their infancy stage. There are a number of methods that have not been utilized effectively, while it is difficult to find a proper abstracted network model to simulate the geographical phenomenon in many occasions. Therefore, to seek more appropriate methods and models for geographical network studies undoubtedly become urgent tasks in this field. In this context, an exploratory research was carried out. First, population flow network of China in the period of "Chunyun", a typical directed-weighted urban network, was built based on the population flow data acquired from “Big data on human migration during the "Chunyun" period from Baidu Map ("Baidu migration data" in short). Sequentially directed alternative centrality and directed alternative power were proposed in predecessor's foundation to evaluate the importance of each node and divide these nodes into different types according to their roles in the urban network. As analysis result, two dimensional spatial characteristic and geographical spatial characteristic was revealed which endowed the methods more practical significances. To validate the effectiveness of the methods, a contrastive analysis of the directed alternative centrality/directed alternative power and centrality/directed alternative power in previous studies was conducted. Based on directed weighted urban network and with the help of this method, this paper classified the cities into quintessential cities, hub cities, gateway cities and periphery cites, and identified the characteristics of agglomeration and diffusion at the mean time. And the result of classification was explained according to the internal structure and external context of the population flow network during the "Chunyun" period. It is found that the regional difference of directed alternative centrality and directed alternative power have certain relationship to economic and social development, national development strategy and administrative division. This explorative process demonstrated that one can effectively extract the information on the hierarchical structure, function divergence and imbalance of the directed weighted urban network via the directed alternative centrality-directed alternative power method. Directed alternative centrality-directed alternative power method is really a feasible approach to analyze the geographical network, and it also demonstrated that directed-weighted urban network can really make a difference from undirected and unweighted network in the geographical network studies.

目前中国地学领域对网络的研究仍处于起步阶段,大量网络研究方法尚未得到应用的同时,许多地理现象尚未寻找到合适的抽象网络模型,不断拓展和应用有效的网络分析方法成为当务之急。在这一背景下,基于百度迁徙平台获取的春运人口流动大数据,构建中国春运人口流动的有向加权城市网络,在已有研究基础上提出有向转变中心性与控制力测度方法,对该城市网络的节点重要性和功能进行评估和分类,分析其呈现的二维空间特征与地理空间分布特征,并与已有方法进行对比。结果表明：利用有向转变中心性和控制力方法,可有效提取有向加权网络的层级结构、功能分异和非均衡性等特征,不但可区分典型城市、枢纽城市、门户城市与边缘城市等不同的城市类型,还可以识别城市的集聚与扩散特征,从而获得比无权无向网络更为丰富和具有实践意义的信息参考,是一种有效的地理网络分析方法。

Networking of the relation among cities is a momentous trend in the development of urban system structure. The connection between cities is often the superposition of multiple elements rather than a single dimension. The urban system of the spatial network of different factor flows differs from each other in spatial organization. Furthermore, the network based on one single factor has obvious limitations so that it is necessary to make a comparative study on the differences of factor flows under the multi-city network. Therefore, this paper, on the basis of four element networks, which are enterprise connection, scientific research cooperation, population migration and gravity simulation, analyzes respectively the external spatial characteristics and disparities of China's urban networks under the perspective of multiple flow space, to be specific, urban node, path connection, community characteristics and etc; explores the internal pattern and law of inter-city connections; as well as attempts to advance proposals to optimize the development of China's urban system. The results reveal that: (1) The spatial organization of multi-city networks shows that the characteristic of similar stability with a “diamond+cross” spatial structure and a “core-node-edge” hierarchical structure, integrates with the characteristic of multiple diversity from the perspective of multi-dimensional data sources; (2) Mobility of population, circulation of materials and other networks that depended on the operation of infrastructure, to some certain extent, are greatly constrained by geographical distance and at the same time show obvious small group characteristics in adjacent areas and strong community structure. However, the less substantial elements such as capital flow and information flow break through this geographical restriction. The focus of the connection lies in the attraction of the target city to the element flow, and the community structure of this type appears to be weak. (3) At present, China's urban connection has the dual characteristics of hierarchy and flattening in form. Therefore, this paper proposes an urban connection model of the “community buzzer-gatekeeper-regional pipeline” model, compatible with the dual features of vertical structure and network structure, applying well for demonstrating the characteristics of China's urban connection, identifying 10 core gatekeeper cities and 8 types of regions in China. Among them, the goalkeeper city with special resources and regional advantages is the leader of the region, playing a key role in undertaking, transforming and spreading various resource elements. This paper aims to improve the theory of urban network and provide theoretical support for urban network development.

城市关系网络化是城市体系结构发展的重要趋势，不同要素流空间网络下的城市体系在空间组织上不尽相同，依托单一要素对网络进行表征的结果具有明显的局限性。本文基于企业联系、科研合作、人口迁徙和引力模拟四类要素网络，从城市节点、路径联系、社区特征等角度剖析多重流空间视角下中国城市网络的外部空间特征与差异，并探究城市间联系的内在模式规律。结果表明：① 多维数据源视角下构建的多重城市网络在空间组织上表现出相似稳定性和多元差异性的统一。② 一定程度上依赖于基础设施运转的人流、物流等网络受到地理距离的约束较大，相邻地区的小团体特征明显，社区结构较强；而资金流、信息流等实体性较弱的要素则突破了这种地理限制，发生联系的重点在于目标城市对于要素流的吸引力，社区结构较弱。③ 目前全国城市联系形态上具有层级性和扁平化的双重特征，据此本文基于“管道-蜂鸣”模型提出“社区蜂鸣-守门员-区域管道”城市空间组织模式，这一模式对于阐述中国的城市联系特征具有较好的适用性，可在全国识别出10个核心守门员城市和8个类型区。

Decreasing spatial transaction and trade costs facilitates the geographical fragmentation of functions, i.e. the stages or activities within product value chain could give rise to functional differentiation of cities. Despite the recent advances in the study of the spatial structure of urban networks, the analysis of functional differentiation of cities across multi-location firms' value chain has been largely neglected. The study sets out to investigate the patterns of functional division of economic activities within China's urban system, and explore the underlying factors with multiple regression models. To this end, data on the corporate networks of China's top 500 public companies in 2018 are collected, and the establishments within the corporate networks are grouped into seven functions: headquarters, business services, research and development, modern manufacturing, standardized production, logistics, and wholesale and retail. The following results are obtained. First, different types of functions within the value chain show different spatial patterns, which leads to the differentiation of urban functions, and promotes the transformation of Chinese cities from sectoral specialization to functional specialization. The three knowledge-rich functions of headquarters, business services and research and development are mainly centralized in the core cities of China's major urban agglomerations, while standardized production has the lowest level of spatial concentration. The second major finding is that functional specialization co-exists with functional diversification within the urban system in China. Overall, large cities are much more functionally diversified, while small and medium-sized cities tend to be specialized in standardized production. Using the clustering algorithm based on self-organizing feature maps, the 334 cities in China can be classified into 9 functional types. Third, location fundamentals play a key role in driving the functional differentiation of cities. Although city size, vital resources, accessibility, urban infrastructure, business environment positively contribute to the presence of all functions, their marginal effects differ across the seven functions. The improvement of economic scale and vital resources will increase the probabilities for cities to develop into headquarter centers, business service centers and R&D centers, while reducing the probabilities of cities is becoming standardized production bases. The traditional urban resource advantages has been transformed into the competitive advantages of urban functional status, suggesting that the development gaps between cities in China will further be enlarged under the network environment.

价值链的空间重组正在深刻的改变着城市体系的经济景观,建立在价值链分工基础上的城市功能结构的研究已经成为经济地理学的重要课题。将中国上市公司500强企业网络划分为公司总部、商务服务、研究开发、传统制造、现代制造、物流仓储和批发零售七种类型功能区块,研究了中国城市价值链功能分工及其影响因素。结果发现：沿着价值链的功能分工已经成为中国城市体系经济景观的显著特征,功能多样化城市和功能专业化城市并存于中国城市体系,东部地区和城市密集地区的城市在价值链分工中占据了更好的地位;中国城市按照价值链中的优势功能可以划分为九种类型,少数城市转变为承载公司总部、研究开发、商务服务等多样化功能的高等级中心城市,而大量中小城市则转变为传统制造专业化基地;市场潜力、关键资源、区位条件、营商环境等城市属性特征是城市功能分工的重要影响因素,城市资源、区位可达性等属性特征的增强将提高城市成为总部基地、商务中心和研究基地的概率,而降低城市成为传统制造基地的概率。

The expansion of leading Chinese companies facilitates the circulation of production factors, and endows cities with the dual role of participating in the internal and external dual circulation. The dual circulation strategy implies that China should "rely on the internal circulation of domestic demand and innovation as the main driver of the economy, and balance emphases on both internationalization and self-sufficiency". In this context, recognizing the functional differentiation of cities participating in the dual circulation is of great significance. Drawing on the organizational network of Chinese companies in the Forbes Global 2000 and Fortune Global 500 list in 2018, this research applies the interlocking network model to map the domestic and international connectivities of Chinese cities. In doing so, it uncovers cities′ different roles in participating in the internal and external circulations, as well as their intermediary functions in the dual circulation. Based on their major business activities, we further divide companies into four sectors: advanced producer service, consumer service, manufacturing, as well as mining and construction. This allows us to examine the sectoral differentiation of cities′ functions. We find that, administrative ranking and level of economic development have a significant impact on Chinese cities′ ability to participate in dual circulations. Our results also suggest hierarchical characteristics: national-level industrial centers have extensive global connections, and they are able to provide high-level products and services. Industrial centers at a regional level, by contrast, have stronger domestic connections, providing lower-level products and services to surrounding areas. Besides, different sectors shape various network structures and city functions. In the network shaped by advanced producer services, cities with high administrative rankings are able to participate the dual circulation; for the general service sector, the ability to participate in dual circulation is more affected by the level of economic development. By contrast, in the case of the manufacturing industry, a larger number of cities are involved in the dual circulation process, with a more scattered spatial distribution; in terms of the mining and construction industries, cities with resource advantages can widely participate in the dual circulation.

重要中资企业的海内外拓展布局,促进了生产要素的循环流动,也赋予了作为空间载体的城市参与链接国内国际循环的双重角色和职能分工。在“加快构建以国内大循环为主体、国内国际双循环相互促进”的新发展格局背景下,认清城市参与双循环的职能分异,对于科学评估城市融入双循环的能级水平具有重要意义。研究从福布斯全球企业2000强和《财富》世界500强中资企业的全球组织网络出发,利用链锁模型映射了企业视角下中国城市的国内国际联系网络,解析了城市参与链接国内国际循环和担任中介节点的职能分异,并分高级生产性服务业、一般服务业、制造业和采矿建筑等四种行业解析了职能分异的行业异质性。研究发现,中国城市链接国内国际循环的职能分异受行政等级和经济发展水平的影响显著,具有明显的层级性。其中,国家级产业中心城市,具有明显的对外服务职能;区域级中心城市,则具有更强的对内服务职能。不同类别行业塑造的网络格局和城市职能分工具有明显差异。

The paper is concerned with spatial clustering of economic activity and its relation to the spatiality of knowledge creation in interactive learning processes. It questions the view that tacit knowledge transfer is confined to local milieus whereas codified knowledge may roam the globe almost frictionlessly. The paper highlights the conditions under which both tacit and codified knowledge can be exchanged locally and globally. A distinction is made between, on the one hand, the learning processes taking place among actors embedded in a community by just being there dubbed buzz and, on the other, the knowledge attained by investing in building channels of communication called pipelines to selected providers located outside the local milieu. It is argued that the co-existence of high levels of buzz and many pipelines may provide firms located in outward-looking and lively clusters with a string of particular advantages not available to outsiders. Finally, some policy implications, stemming from this argument, are identified.

With the rise of the knowledge economy and network society, knowledge collaboration networks have become vital to understanding innovation processes. There are two types of collaboration patterns within interurban knowledge collaboration networks, namely "local buzz" and "global pipelines". This study discusses the characteristics of intraregional and interregional collaboration linkages and their impacts on the knowledge output based on the logic and hypotheses of the "buzz-and-pipelines" model. First, the study proposes novel measures of buzz and pipelines. Second, the study constructs knowledge collaboration networks among 215 cities at prefecture-level and above across 20 urban agglomerations in China based on the co-publication data drawn from the Web of Science. An investigation of the evolution paths and combination patterns of buzz and pipelines in the networks identifies different collaboration patterns among Chinese cities. Finally, the impacts of buzz and pipelines on cities' scientific output are examined. The results show that: (1) The evolution of buzz and pipelines in China's interurban collaboration networks presents cumulative and self-reinforced path dependences. (2) Chinese cities can be categorized into four types, namely "networked", "outward-oriented", "inward-oriented" and "isolated" cities. Different kinds of cities present distinct features in terms of collaboration trajectories and knowledge production. (3) There is an inverted U-shaped relation between intraregional linkages and the knowledge output performance of Chinese cities, whereas the relation between interregional linkages and knowledge output is significantly positive. The relationship between intraregional and interregional linkages is complementary in facilitating cities' knowledge production processes.

知识经济与网络社会时代,知识合作网络成为理解城市创新过程的重要视角。在知识合作网络中,存在两种不同类型的合作模式,即“本地蜂鸣”和“全球管道”。本文以“蜂鸣—管道”模型的逻辑思想和理论假设为基础,探讨区域内和跨区域两种不同城市知识合作模式的特征及其对城市知识产出的影响。首先提出了蜂鸣与管道的测度方法;然后以“Web of Science”数据库为基础构建了中国20个城市群的知识合作网络,考察了网络中蜂鸣和管道的演化路径和组合特征,归纳出城市知识合作模式的不同类型;最后,通过计量模型揭示了蜂鸣和管道对城市知识产出的影响。结果显示：① 中国城市知识合作网络中的蜂鸣与管道表现出渐进积累和自我强化的空间演化特征;② 根据蜂鸣和管道的组合特征,可将城市划分为“网络型”“外向型”“孤岛型”“内向型”4类,不同类型的城市在知识网络中的空间分布规律和发展演进路径存在差异;③ 根据负二项回归模型发现,蜂鸣与城市知识产出呈倒“U”型关系;管道与城市知识产出显著正相关;此外,两种合作模式在促进城市知识生产的过程中存在互补效应。

Urban network research has become the frontier academic field of international urban research and has gradually become a hot spot. At present, the related literature on "urban network" mostly focuses on conceptual discussion, dimension analysis, and network structure analysis. Research on the influence of network on regional economic development is relatively weak. Externality, as an essential attribute of urban network, is of great significance to the evolution of urban network and the development of cities and regions. This article starts from a comparison of agglomeration externalities with urban network externalities, focusing on the review and evaluation of the formation mechanism, utility, and measurement methods of urban network externalities. The synergy effect, integration effect, and borrowing size are considered important reasons for the formation of urban network externalities. The research on the effectiveness of urban network externalities focuses on two aspects. The first is the role of factor flow in promoting knowledge diffusion and innovation, and the second is the impact of urban network on competitiveness and economic growth. Based on the existing literature, the research on the measurement of urban network externalities mainly involves identification and estimation, including three common methods: correlation analysis, regression analysis, and spatial econometric analysis. The existing empirical research on externalities is still mostly based on static analysis and lacks dynamic consideration. To a large extent, the existing research has insufficient theoretical framing and insufficient explanatory power, often resulting in the discovery of conditional associations, but not causal relationships. The Western research on urban network externalities is relatively early and mainly focuses on the global and regional dimensions, while Chinese scholars focus on the national and regional dimensions. In terms of empirical methods and objects, Chinese scholars have also made some innovations based on the study of world city network. The issues that need further attention in the future include theoretical understanding of urban network externalities, externality measurement methods, and empirical research.

城市网络研究已成为国际上城市研究的前沿学术领域并渐成热点,外部性作为城市网络的本质属性,对城市网络的演化及城市与区域的发展均具有重要意义。论文从集聚外部性与网络外部性比较的视角切入,重点对城市网络外部性形成机理、效用和测度方法等方面的研究进展进行梳理和评述。其中,协同效应、整合效应和规模借用被认为是城市网络外部性形成的重要原因。而城市网络外部性的效用研究较多集中在2个方面：一是关注要素流动对知识扩散和创新的促进作用,二是关注城市网络对竞争力提升和经济增长的影响。从已有文献来看,城市网络外部性测度研究主要涉及识别和估算2种类型,包括3种常用方法：关联分析、回归分析和空间计量分析。未来需要进一步关注的问题包括城市网络的外部性理论认识、外部性量度方法以及经验研究问题。

In recent years, network analysis has been widely used to understand urban and regional organizational patterns and their spatial effects. A single city benefits from the scale economy of 'networking' in the inter-city synergy relationship. Some cities or regions also suffer from the loss of resources or elements due to more convenient connections to other cities. The traditional urban endogenous growth theory emphasizing agglomeration economy is no longer suitable to explain the urban and regional organization shaped by 'spaces of flow' alone. The externality of urban network has become another important factor affecting urban growth and regional integration. At present, the existing research (especially in China) is relatively scarce, and most of the studies focus on the spatial pattern and process of the network, and the effects (externalities) of network connections are relatively ignored, i.e., how the urban network externalities interact with the agglomeration economy, which types of cities will benefit or suffer from urban network externalities, and what are the conditions for generating urban network externalities. The above need to be discussed urgently. In order to call on academia to shift more attention on network research to the scientific exploration of 'what' and 'how' regarding the effects of urban and regional development and its optimization, this special issue has selected 15 related papers which carry out the systematic theoretical discussion and empirical research aiming at the 'urban network externalities'. They outline the research agenda on Chinese experience of urban network externalities, and use this as a starting point to promote the deepening of urban network research from pattern description to network performance.

近年来,网络分析被广泛应用至理解城市与区域组织模式及其空间效应中。单个城市在城际协同关系中借助“网络化”的规模经济而受益,一些城市或地区也因更便捷地连接其他城市从而导致资源或要素的流失。传统强调集聚经济的城市内生增长理论不再适宜用来单独解释“流动空间”塑造下的城市与区域组织,而城市网络的外部性成为影响城市增长、区域一体化的另一重要动因。目前,已有的研究（特别在国内）相对匮乏,多集中在网络的空间格局、过程等方面,针对网络联系的效应（外部性）较为忽视,比如城市网络外部性与集聚经济如何相互作用,哪些类型的城市将从城市网络外部性中获益或受损,城市网络外部性的产生条件如何等问题亟需探讨。为呼吁学术同行将更多对网络研究的关注移向探究城市网络对城市与区域发展有何作用、如何作用、怎样优化的科学探索,本专辑精心遴选了15篇相关论文,针对“城市网络外部性”开展系统的理论探讨与实证研究,勾勒城市网络外部性的研究议程与中国经验,并以此为起点推动城市网络研究从格局描述走向网络绩效的研究深化。

Based on the cross-national, cross-regional and regional enterprises’ nonlocal investment data in the Yangtze River Delta (YRD) and applying the social network analysis, panel vector auto regression and geographically weighted regression, this paper reveals the spatial evolution characteristics and interaction effects of the YRD’s multi-scalar urban networks. The results are obtained as follows: Global, national, and regional urban networks in the YRD are in the preliminary, steady, and perfect development stages. Besides, the YRD’s multi-scalar urban networks tend to be regionalized: On a global scale, a dense regional network is gradually forming between the YRD and East Asia, Western Europe, and North America; on a national scale, the connectivity between the YRD and Beijing-Tianjin-Hebei and the Pearl River Delta becomes closer; on a regional scale, there are closer economic ties within the provinces compared with trans-provincial economic ties. Additionally, the network spatial structure dominated by the Shanghai-Nanjing-Hefei-Hangzhou-Ningbo development corridor is forming. When it comes to the interaction effects of the YRD’s multi-scalar urban networks, there is a mutual promotion relationship between the global and national functional connectivity. The improvement of the city’s regional functional connectivity can promote its integration into the global and national urban networks. However, the improvement of the city’s global and national functional connectivity cannot promote its further integration into the YRD’s regional urban network, and its integration into the global urban network even has a significant inhibitory effect on the city’s regional functional connectivity. Furthermore, obvious spatial heterogeneity of interaction effects can be observed, which is coupled with regional economic development patterns.

基于2003—2018年长三角地区跨国、跨区以及区内企业异地投资数据，融合社会网络分析、面板向量自回归模型和地理加权回归模型等方法，探究长三角地区多尺度城市网络空间演化及其动态互馈效应。结果表明：① 全球、全国和区域尺度城市网络分别处于初步发展、稳步发展和完善发展阶段，各尺度网络均呈现出区域化倾向，以沪宁合杭甬发展廊道为支撑的网络空间结构正在形成。② 城市的全球与全国功能联系之间存在相互促进的关系；城市的区域功能联系提升能够促使其融入全球和全国尺度城市网络，反之，城市的全球与全国功能联系提升却未能促进其进一步融入长三角内部城市网络，融入全球尺度城市网络甚至对城市的区域功能联系产生显著的抑制作用。此外，多尺度城市网络互馈效应具有明显的空间异质性，并与区域经济发展格局相耦合。

In the context of economic globalization and regional integration, urban development forces have shifted from geographical agglomeration to external network coordination. The connectivity among cities or city network is increasingly becoming “the second essence of cities”. With bibliometric analysis of urban network externality studies, we find that spatial econometric models have been increasingly employed to quantify whether, and to what extent, urban network externality matters in the developmental process of cities or regions. This study first investigated the mathematical properties of spatial econometric models and in particular, the correspondence of model parameters and various measures of urban network externality. More importantly, we highlighted two essential issues of classic spatial econometric models when being applied to model urban network externality: the asymmetric effect and scale effect of urban network externality. Then, we developed an asymmetric spatial economic model (ASEM) to capture the asymmetric effect of urban network externality and, a hierarchical spatial autoregressive model (HSAR) to deal with the scale effect of urban network externality. A series of Monte Carlo simulation experiments were conducted to assess the benefits of these two proposed methodologies. We found that: (1) Ignoring the potential asymmetric effects in the urban network will significantly reduce the accuracy of model parameter estimation. On the other hand, the proposed ASEM can accurately identify the asymmetric effects of network externalities and yield more accurate parameter estimation. (2) Ignoring multi-scale network effects in real world data and modeling the network effects at a single scale will cause serious estimation distortion. The HSAR model instead can provide a reliable quantitative method for modeling the externalities of multi-scale networks.

在经济全球化、区域一体化的背景下，城市发展动力由内部功能集聚转向外部关系协调，城市间的关联作用愈发重要，成为“城市的第二本质”。通过文献计量分析，发现空间计量模型逐渐成为城市网络外部性定量测度的主要方法之一。从研究设计角度，空间计量模型作为城市网络外部性的定量建模工具，存在至少两方面的问题：城市网络外部性的非对称效应和城市网络的多尺度问题。本文结合城市网络外部性测度与建模，首先阐述如何规范地解读空间计量模型参数及其与网络外部性测度的对应关系；其次基于蒙特卡洛模拟实验论证非对称城市网络外部性和多尺度城市网络外部性的建模方法。研究表明：① 忽视城市网络外部性中潜在的非对称效应会显著降低模型参数估计的准确性，本文开发的非对称空间效应模型（Asymmetric Spatial Econometric Model，ASEM）可以准确识别网络外部性的非对称效应，给出更加准确的参数估计；② 忽略现实存在的多尺度网络效应，只在单一尺度对网络效应建模会造成参数估计失真，而空间多尺度统计模型（Hierarchical Spatial Autoregressive model，HSAR）为多尺度网络外部性建模提供了有效的工具，并且通过合理的模型设定，HSAR能准确区分并识别地理集聚效应和网络外部效应。

With the rapid development of high-speed transportation technology and mobile communication infrastructure, urban innovation activities are no longer confined to a specific geographical space, and there is still a lack of empirical evidence on whether synergistic innovation can be achieved between cities that are far from each other but have strong business linkages in cyberspace. Based on the macro panel data of 289 prefecture-level cities and the micro data of listed-companies in China from 2001-2016, this paper portrays the spatial distribution of innovative activities, and then quantitatively analyzes the impact of agglomeration externalities and network externalities on urban innovation development using social network analysis (SNA), instrumental variables approach (IV) and spatial durbin model (SDM). The findings show that innovation factors still tend to be concentrated in the head companies and the central cities, and it is the agglomeration externality brought by this concentration that promotes the innovation development of the head companies and the central cities; moreover, the nodal cities benefit their innovation development from network externalities caused by cooperation with other cities through the corporate affiliate network or the investment network. In terms of different transmission mechanisms between agglomeration and network externalities for urban innovation development, the level of government spending on science and education, the level of urban infrastructure, and the operation of high-speed rail networks are important conditions for the agglomeration externalities and network externalities to improve the urban innovation. However, the agglomeration externalities arising from the increased density of economic activity can also reinforce the innovation effects brought by network externalities, while the advanced technology and management experience brought by foreign direct investment activities help network externalities to break through the limits of geographic space and improve the level of the urban innovation. Based on these findings, the government, in exploring the path of urban innovation development, need not hoard on the spatial agglomeration of innovation factors as the only path, but lead cities to actively participate in the construction of international science and technology innovation centres within city clusters, which can also achieve innovation development with the new knowledge and technology shared in the business network.

随着高速交通技术和移动基础设施的迅速发展,城市创新活动已经不再局限于特定的地理空间,在网络空间中彼此远离但有着较强经济活动关联的城市之间是否也可以实现协同创新,目前仍缺乏经验证据。基于2001—2016年中国289个地级市宏观面板数据和微观层面上市公司数据,采用社会网络分析法、工具变量法以及空间杜宾模型等方法,定量研究了集聚外部性与网络外部性对于城市创新发展的影响。结果显示：创新要素依旧存在着向头部企业和中心城市集中的趋势,且正是这种集中所带来的集聚外部性促进了城市的创新发展;城市可通过融入经济关联网络,借助于网络外部性来提高自身创新水平;就集聚外部性与网络外部性促进城市创新发展的传导机制来看,虽然政府科教支出水平、城市基础设施状况以及高铁网络的建设是集聚外部性与网络外部性发挥的重要条件,但经济活动密度的提升所带来的集聚外部性还可以强化网络外部性所带来的创新效应,而外商直接投资活动所分享的先进技术和管理经验则帮助网络外部性突破了地理空间的限制。因此,政府在探索城市创新发展路径的过程中,就无需囿于创新要素的空间集聚这一条路径,积极融入城市群内的国际科技创新中心建设,凭借网络外部性所分享的新知识与新技术,同样也能实现创新发展。

Innovation is acknowledged as the main driving force of the sustained growth of regions. In the literature on innovation geography, multidimensional proximity has become an important proposition that helps to understand the structures, processes, and mechanisms of regional innovation and the formation of innovation networks. However, many studies focus on the independent effect of different types of proximity on regional innovation, and much less attention has been paid to their joint effect. Moreover, in terms of methodology, studies on proximity have been dominated by quantitative approach on macro level, and very few cases can be found with in-depth qualitative approach on micro level. Based on the co-publication data from the Web of Science database, the study constructs an interorganizational collaboration network of medical sciences in the Jiangsu-Zhejiang-Shanghai (JZS) region. With combined approaches of quantitative and qualitative methods, the study explores the impacts of, and joint effects (substitutional and complementary effects) between geographical proximity and non-geographical proximity (institutional, social, cognitive and cultural proximity) on the formation of the collaboration networks in this field of the region from both macro and micro perspectives. First, we use the method of the MRQAP regression to quantitatively examine the independent and joint effects of geographical and non-geographical proximity on the formation of scientific collaboration network of the medical sciences in the region. Second, we conduct semi-structured interviews with four selected interorganizational collaborative groups in the region to reveal how these different types of proximity affect the motivation of collaborations. The results of both quantitative and qualitative analyses support each other and show that (1) each form of proximity has a positive impact on regional knowledge collaboration with the exception of cultural proximity. (2) Geographical and institutional proximity can be substituted in their influence on the formation of regional knowledge collaboration network. (3) The relations between geographical and social/cognitive proximity are complementary. (4) There is no significant joint effect between geographical and cultural proximity. This study not only examines the relations between multidimensional proximity and the formation of innovation networks by quantitative methods, but also explains why such interrelations exist through qualitative approach.

本文以Web of Science数据库的合著论文信息为基础构建江浙沪区域医学科研机构合作网络,采用计量分析与半结构化访谈相结合的方式从宏观和微观层面考察多维邻近性（地理邻近性、制度邻近性、社会邻近性、认知邻近性和文化邻近性）对该区域医学领域创新合作网络形成的影响,并进一步讨论了地理邻近性和非地理邻近性之间的交互效应（替代效应或互补效应）。综合定量与定性分析结果,研究发现：① 地理邻近性、制度邻近性、社会邻近性和认知邻近性对该区域医学创新合作网络的形成有促进作用,而文化邻近性的作用不显著;② 地理邻近性与制度邻近性之间存在替代效应;③ 地理邻近性与社会邻近性、认知邻近性之间均存在互补效应;④ 地理邻近性与文化邻近性之间不存在显著的交互效应。

Is there is a phenomenon of "low-end locking" in the urban network? Can low-grade cities benefit from the urban network? Have high-grade cities played a leading role in the urban network? These issues are related to the strategic orientation of the development of urban agglomeration, which is still lack of in-depth research. Urban network externalities refer to cities benefited by connecting with other cities, which provides a theory for answering the above questions and has become a new hotspot in urban network research. Existing studies focus on the overall characteristics of urban network externalities, but ignore the differences of urban network externalities between cities. In this paper geographical weighted regression model is used to accurately measure the urban network externalities to each city and reveal the spatial heterogeneity of urban network externalities. Taking 41 cities in the Yangtze River Delta region as case studies, we construct the urban network according to the scale of mutual investment of enterprises between cities. Then we analyze the influence of network connection on urban development, which proves that there exist urban network externalities in the study area. The results are as follows: (1) Although the urban network externalities are not dominant, joining urban networks has played a positive role in the urban development of Jiangsu, Zhejiang and Shanghai. (2) There are great regional differences in urban network externalities. The urban network externalities of cities in Jiangsu are generally stronger than those of Zhejiang, while those in Anhui are not strong. Urban development is still mainly determined by the local agglomeration of people, land and capital. (3) The urban network externalities in the Yangtze River Delta are formed mainly under the influence of Shanghai, but the influence of the three provincial capitals — Nanjing, Hefei and Hangzhou — is limited. (4) Although low-grade cities have not benefited from the network, they are not "low-end locking" either. High-grade cities do not form a "cluster shadow" around them. This paper hopes to improve the theory of urban network externalities and provide theoretical support for regional network development.

城市网络中是否存在“低端锁定”现象,低等级城市能否从网络中获益,高等级城市是否发挥了辐射带动作用,这些问题关系城市群发展的战略导向,当前仍缺乏深入论证。城市网络外部性是指城市因联系而得到的效益,为回答上述问题提供了理论依据,已成为城市网络研究的新热点。但现有研究主要关注网络外部性的整体特征,忽视区域内城市间的网络外部性差异。本文使用地理加权回归模型将网络外部性测度精确到每个城市,揭示网络外部性的空间异质性特征。研究以长三角地区41个城市为研究对象,按城市汇总企业之间相互投资规模构建城市网络,分析网络联系对城市发展水平的影响,证实了长三角地区存在网络外部性。研究发现：① 虽然网络外部性未成为主导,但嵌入城市网络已经对江浙沪城市发展起到了积极影响。② 网络外部性的地域差异较大,江苏省城市的网络外部性普遍强于浙江省,安徽省的网络外部性不强,城市发展仍主要由人、土地和资本的本地集聚决定。③ 长三角地区的网络外部性主要是在上海的辐射带动作用下形成的,3个省会城市南京、合肥、杭州对周边城市的辐射带动作用有限。④ 低等级城市虽未从网络中获得明显的效益,但也未被“低端锁定”,高等级城市没有在周边形成“集聚阴影”。本文希望能有助于完善城市网络外部性理论,为区域网络化发展提供理论支撑。

It is of great significance to analyze the main environmental issues, coupled with their spatial heterogeneity, and divide the ecological function zones to achieve ecological security and optimization of territory development in a certain region. In recent years, ecological function zoning, widely concerned by scholars, has played a vital role in regional ecosystem management and sustainable development. There arose a problem that the spatial characteristics of ecological functions were hard to be reflected in the previous studies based on spatial average data over basins or geopolitical regions such as counties, cities and provinces. This paper, using the approaches of coupling self-organizing feature map (SOFM) and support vector machine (SVM), attempts to develop an automatic demarcation and zoning approach, and explores the best possible division of ecological functions in the city of Ordos with the index system of ecological function zoning in mind involving the ecosystem services as well as ecological sensitivity. Ordos, which is located in the transitional zone between temperate grasslands and desserts, has become a key research area of global terrestrial ecosystem. The ecological functional zoning indexes indicate that there appears an obvious spatial heterogeneity of ecosystem functions in Ordos. Accordingly, land grids have been clustered into 7 ecological function types by SOFM with clustering quality index (CQI) in view. Hence, Ordos has been divided into 11 ecological function zones owing to the implementation of SVM to identify the optimal division borders, in which the border demarcation is treated as a classification system in spatial domain. The optimal combination of SVM hyperparameters is determined by grid search method. In this study, machine learning algorithm has been adopted to cope with the situation where the bottom-up physical regionalization might weaken the spatial position attribute of the partition features, and to realize the quantitative conversion from classification to partition. It has turned out that such SOFM-SVM-coupled zoning approach could effectively improve the spatial accuracy of the partition, which can be considered as a new way to realize the automatic ecological zoning.

辨析区域主要生态环境问题及其空间异质性,划定生态功能区,对保障区域生态安全和国土开发优化具有重要指导意义。以往自下而上的分区研究多基于行政区或流域开展,难以体现行政区或流域内部的生态功能分异。以鄂尔多斯市为例,基于生态系统服务与生态敏感性构建区域生态功能分区指标体系,耦合自组织特征映射（SOFM）网络与支持向量机（SVM）划定鄂尔多斯市生态功能分区。结果表明,区域内各生态功能分区指标呈现明显的空间分异特征,通过SOFM网络基于栅格进行指标聚类,构建分类效果指数筛选最佳聚类方案,将区域分为7种不同的生态功能类型。最终,利用SVM识别最优分区界线,将鄂尔多斯市分为11个生态功能区。本文构建分类效果指数实现多分类方案优选,使用机器学习算法解决自下而上的自然分区容易弱化要素空间位置属性的问题,完成了从分类到分区的定量转换,有助于提升分区的空间精度与客观性,为生态功能分区与分区边界划定提供了新的方法途径。

Spatial stratified heterogeneity is the spatial expression of natural and socio-economic process, which is an important approach for human to recognize nature since Aristotle. Geodetector is a new statistical method to detect spatial stratified heterogeneity and reveal the driving factors behind it. This method with no linear hypothesis has elegant form and definite physical meaning. Here is the basic idea behind Geodetector: assuming that the study area is divided into several subareas. The study area is characterized by spatial stratified heterogeneity if the sum of the variance of subareas is less than the regional total variance; and if the spatial distribution of the two variables tends to be consistent, there is statistical correlation between them. Q-statistic in Geodetector has already been applied in many fields of natural and social sciences which can be used to measure spatial stratified heterogeneity, detect explanatory factors and analyze the interactive relationship between variables. In this paper, the authors will illustrate the principle of Geodetector and summarize the characteristics and applications in order to facilitate the using of Geodetector and help readers to recognize, mine and utilize spatial stratified heterogeneity.

空间分异是自然和社会经济过程的空间表现,也是自亚里士多德以来人类认识自然的重要途径。地理探测器是探测空间分异性,以及揭示其背后驱动因子的一种新的统计学方法,此方法无线性假设,具有优雅的形式和明确的物理含义。基本思想是：假设研究区分为若干子区域,如果子区域的方差之和小于区域总方差,则存在空间分异性;如果两变量的空间分布趋于一致,则两者存在统计关联性。地理探测器q统计量,可用以度量空间分异性、探测解释因子、分析变量之间交互关系,已经在自然和社会科学多领域应用。本文阐述地理探测器的原理,并对其特点及应用进行了归纳总结,以利于读者方便灵活地使用地理探测器来认识、挖掘和利用空间分异性。