Spatio-temporal Structure And Evolution Of Knowledge Network On Urban Scale

Knowledge network,as an important way to grasp the laws of scientific knowledge development and enhance the collaborative innovation ability of cities,has achieved fruitful research results in exploring the structural characteristics and evolutionary dynamics of knowledge network.However,the current researches are more about the formation mechanism,evolution law and dynamics of knowledge network from the linear dimension of time,and less about the spatial organization of knowledge networks,especially the spatial structure and pattern evolution of knowledge network at the urban scale.It is important for revealing the spatial structure,pattern change and innovation effect of knowledge network to improve urban innovation ability and the construction of innovative country.Based on the theories and methods of spatial scientometrics,urban geography,econometrics and other interdisciplinary disciplines,this paper explored the spatial structure,evolution process and innovation mechanism of knowledge network and geographical network.Meanwhile,some mathematical models are established to discover the law of spatial organization and evolution of knowledge network,which undoubtedly have far-reaching theoretical and practical significance for understanding the spatial flow characteristics,dynamic evolution mechanism and reconstruction process of knowledge network.The related research work of this paper is supported by the major projects of the National Natural Science Foundation of China “Comprehensive information integration and analytics of big data for national security”(71790612),and the National Natural Science Foundation project “Dynamic evolution law of scientific research teams”(71273196).The main work includes the following aspects:1.Mining the spatial structure and key characteristics of knowledge network.Taking the field of energy conservation as example,the structural characteristics of knowledge-knowledge network,knowledge-geography network and urban cooperative network were analyzed and key knowledge nodes,connections and topological structures in different networks were identified.In additon,the potential cooperative relationships were discovered by measuring the similarity of knowledge in different cities,and the structural coupling was explored between potential and realistic cooperative networks.Empirical analysis shows that the distributions of knowledge association,knowledge spatial and cooperative relationship meet power-law distribution.Moreover,the three networks show obvious community structure and aggregation effect.For the hierarchical structure of knowledge network,the basic layer reflects the most basic and core knowledge structure but the middle layer and detail layer represent the micro knowledge structure.The spatial distribution of different layers is different as well.This chapter focuses on the knowledge association,manifestation,internal structure and topological differences of knowledge network,which is the basis for further exploring the processes of dynamic evolution,spatial diffusion and knowledge innovation.2.Exploring the knowledge complexity and spatial association in knowledgegeographic network.The spatial complexity measurement model of global urban knowledge was constructed,and the essential differences of different urban knowledge were revealed by measuring knowledge complexity based on dual-mode network model.The spatial clustering and autocorrelation of knowledge complexity were explored by using spatial statistical analysis.In addition,the evolution model of knowledge stickiness was constructed to discover the relationship between knowledge complexity and knowledge stickiness in the process of knowledge transfer.The experimental results show that the knowledge complexity satisfies the spatial global and local autocorrelation characteristics,and different influencing factors have different degrees of oscillating effects on knowledge stickiness.This chapter explored the spatial cohesion and its role in knowledge transfer,which can provide reference for promoting urban competitive advantage and knowledge flow in the network.3.Revealing spatial evolution process and effect mechanism of knowledge network.The structural evolution characteristics of the three networks were revealed by drawing the geographic process of knowledge network.The dynamic evolution model was established based on hypergraph theory and cross-preferential connection mechanism.On this foundation,the relation of knowledge diffusion and network topology structures,preference selection,knowledge growth,knowledge genetic inheritance and abrupt variation were discussed.The empirical results show that the diversity of topics and the intensity of cooperation in the energy conservation field are gradually increasing,while the spatial distribution of knowledge remains stable.The smaller scale of cooperation network has and the more significant the spillover effects of experts are,the more effectively the knowledge diffusion is promoted.Genetic inheritance and abrupt variation work on the performance of knowledge diffusion in some different degree and achieve a state of equilibrium at a certain moment.4.Analysing the influencing mechanism of innovation performance based on multi-level networks.This paper explores the impact mechanism of innovation performance under the interaction of knowledge network and cooperative network from the perspective of multi-layer network.The K-kernel decomposition method was used to identify the core structure of the whole knowledge network and urban knowledge networks in each period.The distance between the core structures was calculated to measure the embedding depth and breadth of knowledge network and the structural entropy was measured based on the node and edge heterogeneity as well.Based on that,the impacts of embedding depth and breadth,structural entropy,urban agglomeration index,influence and spatial distance of urban knowledge network on urban technological output are examined.The experimental results show that urban innovation performance is determined by the joint effect of urban cooperation network and its own knowledge network,and the two networks affect urban innovation performance in different mechanisms and ways.This chapter attempts to to explore the effective motivation and mechanism of innovation performance,which can provide reference for implementing and putting forward innovation decision-making and strategy.