Uncovering Urban Spatial Interaction Based On Multidimensional Hawkes Process And Population Flow

Urbanization refers to the process of population transfer from rural areas to urban areas,which enables urban development.A series of complex problems have appeared in the process of urbanization in China.The National New Urbanization Plan(2014-2020)points out that in order to build new-type cities and towns with ecological civilization,the planning of urban system,reasonable spatial pattern and quantitative structure are crucial,and attention should be paid to the guiding role of urban planning in the process of urbanization.Urban spatial interaction can reveal the interdependence between urban regions,help to better understand the urban spatial structure,optimize the layout and form of urban areas scientifically,and have a guiding significance for a new-type urbanization based on ecological civilization.There are many factors of flow in the urban system,covering all aspects of daily production and life,such as commodity flow,currency flow,population flow and information flow.The flow of elements can reflect the interaction between urban space.Traditional research on urban spatial interaction mainly focuses on the analysis of material flows such as commodity flow,currency flow and information flow,neglecting the role of people in shaping urban space.In addition,the traditional research mainly uses the gravity model,which relies on artificial judgment and analysis in the choice of parameters and the form of functions,meanwhile,the results obtained are not bidirectional.In view of the above deficiencies,this thesis has done the following work:1.A model of urban spatial interaction based on multidimensional Hawkes process and population flow is constructed.Urban structure is shaped by human interaction mode,and urban spatial interaction is the accumulation of human daily activities in the long-term process.Compared with inter-regional material flow,inter-regional population flow can better reflect the interaction of urban space.In this thesis,large-scale and real-time mobile phone data is used to extract the user movement trajectory sequence,and the sequence is input into the urban spatial interaction model based on the multidimensional Hawkes process.The model uses the self-exciting and mutual-exciting characteristics of the multidimensional Hawkes process to describe the bidirectional spatial interaction between regions.The parameter estimation algorithm of the model is presented and the accuracy of parameter estimation is verified in the simulation dataset.The performance of the model is evaluated in real dataset,and it is found that the results obtained by the model are consistent with the results obtained by the traditional gravity model but are more abundant,which indicates that the model could better identify the urban spatial interaction.2.Take Yiwu City as an example to study the interaction between urban space.By analyzing the intrinsic attractiveness of the region,we can see that Choucheng Street and Futian Street are the two strong gravitational cores in Yiwu.Then,we study the interaction between regions.From the perspective of self-exciting,it is found that economically developed regions have a stronger self-exciting intensity,showing that residents living in economically developed regions have a stronger stickiness.Residents tend to conduct activities within the region,and the service facilities within the region can meet the needs of daily life of residents.From the perspective of mutual-exciting,there is stronger interaction between neighboring streets/towns.It is found that Jiangdong Street-Choucheng Street,Dachen Town-Suxi Town,and Fotang Town-Chian Town form a "circle"interaction pattern,which indicates that these streets/towns have close functional connections.From the perspective of outward interaction,the direction of outward interaction of several streets/towns in Yiwu points to Choucheng Street or Futian Street,which shows that the direction of outward interaction presents the direction of the central town of the city.From the perspective of inward interaction,Choucheng Street form a"wing-shaped" attraction structure from southwest to northeast to the surrounding streets/towns.The surrounding streets/towns around Suxi Town form a "encircling"attraction structure in the four directions of Suxi Town.The work in this thesis provides a new perspective for the identification of urban spatial interaction,helps to understand the urban spatial structure,and makes scientific judgments and suggestions on the development potential,industrial coordination,resource allocation and other issues of cities and towns,thus providing a reference for the promotion of new-type urbanization.