Research On Heat Storage And Release Characteristics And Enhanced Heat Exchange Of Phase Change Heat Storage Devic

The internal spatial structure of cities has been one of the most important research topics in policy and academia.From a policy point of view,since the reform and opening up,especially since the beginning of this century,with the continuous intensification of urbanization in my country,a large number of people have poured into cities,and the internal spatial structure of cities has undergone earth-shaking changes.The density is too high and the anti-risk ability is not strong.In recent years,the topics of how to adapt to the new situation,implement regional optimization and spatial governance have always been the focus of policy attention.The outline of the "14th Five-Year Plan" mentioned that it is necessary to build a high-quality development of land and space layout and support system.General Secretary Xi also recently emphasized the need to build a number of suburban new cities with convenient transportation to promote the development of urban multi-center and suburbanization.Based on this policy orientation,many measures have been introduced in recent years,ranging from regional coordinated development to urban function relaxation.However,there are still contradictions and challenges such as disorderly urban sprawl and inefficient use of land caused by insufficient power to shape urban spatial structure,which seriously hinders the city’s operational efficiency.Therefore,how to correctly shape the urban internal spatial structure and achieve the goal of high-quality urban development has become a key issue to be solved by the policy community.From a practical point of view,the area of urban built-up areas in China has more than doubled in the past 20 years,and the spatial range extends from the main city center to the periphery for dozens of kilometers.change.Although the factors affecting the internal spatial structure of cities include natural endowment,economic level,public services,traffic conditions,etc.,for a long time,due to the limitation of data and the complexity of practical problems,the research on its influencing factors is still insufficient.At the same time,great changes have taken place in China’s expressways over the past 20 years.A large number of studies have confirmed their important role in promoting coordinated regional development and reshaping economic geography,but they have long ignored the impact of expressways on urban interior space.Judging from actual cases,the new urban centers mainly appear along the expressways in the periphery of the city.It is preliminarily speculated that the construction of expressways is an important reason for accelerating the transformation of the urban interior space structure from single center to multi-center.From a theoretical point of view,traffic is not the only factor that determines the internal spatial structure of a city,but an important dominant factor that plays a leading role.From the earliest agricultural location theory,industrial location theory,market location theory,to the later introduction of single-center and multi-center theoretical models,all of them have consistently emphasized the important role of transportation accessibility in shaping the spatial structure.Based on its own characteristics of reducing the cost of freight transportation,the completion of expressways will raise the overall land price level of the city,improve the accessibility level of the areas along the line,and then affect the behavior of the government,enterprises and residents within the city,and accelerate the flow of economic factors,thereby changing the city.Internal space structure.From a literature perspective,in recent years,the emergence and application of highresolution datasets such as nighttime light data and population raster data have also provided more empirical evidence for this research.Based on samples from European and American countries,Baum-Snow,Garcia-López,etc.affirmed the positive role of highways in promoting suburbanization and decentralization.However,domestic scholars have been trying to explain the economic performance of the internal spatial structure of Chinese cities,and the research on the formation mechanism of the spatial structure is still insufficient.Therefore,from the perspective of urban interior,this paper focuses on the impact of transportation infrastructure represented by expressways on the urban interior spatial structure and its internal impact mechanism,and attempts to explain the spatial heterogeneity of urban interiors.This is of great significance for enriching the theory and literature of urban interior spatial structure,and guiding future highway construction and spatial structure policy formulation.The research of this paper revolves around the core proposition of "whether the expressway has reshaped the internal spatial structure of the city and its internal influence mechanism".It starts from various aspects such as analysis and empirical analysis,adopts interdisciplinary and multi-angle research methods,and narrates through seven chapters:The first chapter is the introduction.This part first introduces the research background,and points out that the internal structure of Chinese cities is undergoing great changes through some data lists,but how to promote the rational layout of transportation infrastructure and public services in the city through planning and governance.In the following part,the main concepts,research contents,research methods,research data,research difficulties and innovation points are expounded.This paper mainly investigates the impact of highway,the transportation infrastructure,on the internal spatial structure of prefecture-level cities,and based on the micro-grid space The mechanism test of big data and prefecture-level city data,as well as the use of micro-enterprise innovation data to carry out after-effect test,have certain innovations in research perspectives,research data,and research methods.The second chapter is literature review.This part is mainly to understand the domestic and foreign research context and research frontier under this topic by sorting out the research literature on urban internal space structure,transportation infrastructure and the impact of transportation infrastructure on urban internal space structure.Firstly,it reviews the connotation,measurement methods,influencing factors and effect evaluation of urban interior spatial structure.In general,urban spatial structure is defined as the distribution and combination state of economic elements in the spatial scope,including the spatial structure of economy,industry and population,etc.,which has always been an important issue in the research of regional economics.Its measurement methods are generally divided into parameter method,threshold method and non-parameter method.Then combine transportation infrastructure for economic growth,population distribution,land use and urban internal spatial structure study found that existing research is based on samples of European and American countries metropolitan area for highway and subway promote suburbanization,decentralized study provides empirical evidence,affirmed the transportation infrastructure in shaping the positive role of the urban space structure.However,the existing literature focuses on the economic and innovation performance of China’s urban polycentric spatial structure,and the analysis of the formation laws and shaping methods of urban spatial structure is still insufficient.In particular,the current discussion of China’s urban spatial structure fails to bring the government’s uniquely Chinese policies on development zones and the planning role of land markets into the analytical framework,which is one of the objectives of this study.The third chapter is theoretical analysis.Based on the classical single-center model,O ’Sullivan(2013)and Wei Shouhua et al.(2016)are used for reference and extension.Combined with the relevant ideas of spatial equilibrium theory,this part introduces the impact of transportation cost change brought by highway construction and considers the flow of land,enterprises and population factors.In this paper,the shaping process of polycentric spatial structure by highway and its possible influencing mechanism are deduced theoretically.Studies have found that is different from the European and American countries bottom-up urbanization background,China’s transportation infrastructure and urban spatial structure is the result of the government behavior,more distribution in the peripheral areas of highway construction impact will induce local government behavior in the peripheral region of urbanization,accelerating the new development of land and population factors,manufacturing enterprises to city agglomeration,reverse spatial structure layout.The fourth chapter is the current situation analysis.This part introduces the measurement,development characteristics and trends of China’s highway construction,and the measurement and evolution trend of the polycentric spatial structure in Chinese cities by comprehensively using the manually sorted highway construction routes and traffic information,as well as the Land Scan high-resolution global population distribution data.and spatial characteristics,as well as the correlation analysis and typical facts of China’s highway construction and urban interior spatial structure.The study found that China’s large-scale highway construction since the beginning of this century has provided an excellent sample for identifying the urban space shaping effect of highways;at the same time,it is also seen that most cities in my country are evolving in the direction of increasing polycentricity.The fifth chapter is the empirical test.Based on multiple sets of expressway indicators and spatial structure indicators,this part systematically identifies the impact of expressways on spatial structure by comprehensively using instrumental variables such as historical traffic routes and planned routes.The results of the study show that the city has a radial highway from the center to the periphery or a highway transiting at the city fringe,which is conducive to the transformation of the spatial structure from a single center to a multi-center,while the ring-shaped highway does not bring about the transformation of the spatial structure.In addition,the results of heterogeneity analysis show that expressways have a stronger role in shaping the internal spatial structure of large cities,eastern and central cities,southern cities and cities with a higher proportion of service industries,while shaping the internal spatial structure of central and non-central cities.There was no significant difference in effect.Finally,based on the evaluation results of economic effects after expressways shape the spatial structure,this paper finds that the more the urban spatial structure tends to be more multi-center,the more conducive to the development of enterprise innovation performance,and the expressway plays an important role in promoting it.The sixth chapter is the influence mechanism test.Focusing on the three types of influence mechanisms that accelerate the transformation of the spatial structure of expressways to a multi-center direction,this part comprehensively uses the 2001-2017 land use raster data,the 2001-2019 land market network land transfer data,and the2001-2013 industrial enterprise location data,etc.At the same time,the expressway accelerates the decentralization of the population,significantly increasing the share of the population beyond 5km of the urban CBD.At the same time,this paper also uses1km×1km micro-raster data to carry out rich micro-mechanism tests,which also verifies the above influence mechanisms.The closer a space unit is to the expressway,the higher the density of new development plots,manufacturing enterprises and population,and the higher the possibility of building a development zone.The layout along the line triggers the development of nearby land,which in turn has an impact on the internal spatial structure of the city.The seventh chapter is the research conclusion and policy implications.Based on the main research conclusions of this paper,the following points should be paid attention to in future transportation infrastructure construction and spatial planning policy formulation: First,in China’s future urbanization process,it is still necessary to actively encourage the multi-center development strategy and guide it rationally.Second,in the process of multi-center development,the transportation infrastructure construction of sub-centers should be strengthened,and the basic service facilities should be improved.Third,the leading role of the government should also be adhered to in the process of multi-center development.Fourth,we should give full play to the leading and leading role of large cities in multi-center practice,and at the same time do a good job in the spatial planning and design of small and medium-sized cities.Fifth,to give full play to the role of expressways in shaping the multi-center structure,it is necessary to fully consider the heterogeneity factors such as city scale,urban location,and urban industrial structure,and proceed in an orderly manner according to local conditions.