Research on urban health constitutes an important issue in the field of health geography and also a strong propeller of the Healthy China Initiative. As the main form that realizes new-type urbanization, urban agglomerations should become the primal sites for the construction of a "Healthy China". The evaluation of healthy cities' development in urban agglomerations has both theoretical and practical values. Based on the concept of urban health and its evaluation models, this paper developed an evaluation framework for healthy cities that involved multiple data sources. With 19 urban agglomerations in China as the research subjects, we used CRITIC weighting and geographical detectors to examine the spatial and temporal development patterns of healthy cities and their influencing factors in 2010 and 2020. The results were fourfold. Firstly, the urban health level of China significantly increased from 2010 to 2020, and the comprehensive health index developed towards a positive skewed distribution, along with a shift from "low in the hinterland - high in the coastal areas" to a "multipolar" pattern led by the coastal and southwest urban agglomerations. Secondly, among various dimensions of urban health, the healthy environment index became improved with narrowed regional differences; while the health services index was still polarized; health collaboration was upgraded with a strengthened intercity health networks; the healthy population index slightly declined and converged to the middle. Thirdly, urban health in China has initially demonstrated the characteristics of a H-H pattern in the Yangtze River Delta and Chengdu-Chongqing regions, as well as L-L clusters in the northern urban agglomerations, the narrowed regional differences, and increasing coordination within each urban agglomeration. Fourthly, the geographical detector found that economy, urbanization and the human capital were significant external factors that affected urban health development. The explanatory power of technological innovation and openness to the outside world were also increasing. The development of healthy cities is yet to be transformed into regional health integration.

This paper aims to examine the characteristics and patterns of the spatial linkage networks of urban economic efficiency so as to provide new policy insights into the regional integration process. The study builds a theoretical framework to analyze the spatial linkage of urban economic efficiency among cities from the perspective of scaling law. It constructs an analytical paradigm to reflect the network externalities. The Yangtze River Delta Urban Agglomeration (YRDUA) is selected as a case study, and the improved gravity model and social network analysis are applied to measure the urban economic efficiency from 2000 to 2020, analyze the strength of inter-city linkages, and construct a spatial linkage matrix. The results reveal that: (1) the high economic efficiency zone of the YRDUA is gradually shifted from the high-grade cities in the east to the low-grade cities in the northwest; (2) the high-grade cities occupy a central position in the network, forming solid links and "small groups" with the neighboring cities; (3) in the linkage pattern of the urban agglomeration, the Shanghai-Suzhou, Hangzhou-Ningbo, and Hefei clusters show a dual-center, radiation-type and siphon-type coexistence. In contrast, the Nanjing cluster shows a single-center radiation pattern. The linkage paths of the cities in these four clusters are relatively fixed, and the linkage patterns evolve slowly. These findings coincide with the theory of city "quality" in urban geography and the theory of city links in economic geography, and provide empirical support for the integrated and coordinated development of the YRDUA, as well as emphasize the importance of the coordinated development pattern of the "wild goose" echelon structure, which is essential for the understanding of the development of the YRDUA.

Urban shrinkage has gradually become a global economic and social phenomenon, and housing vacancy is an important concomitant effect of urban shrinkage. Housing vacancy in shrinking cities is a key issue that needs to be studied urgently. Taking Northeast China, a concentrated area of shrinking cities in the country, as the research object, this study uses multiple types of remote sensing imagery data and spatio-temporal big data to construct a shrinking city system based on the perspective of physical urban areas, estimate the housing vacancy rate, analyze the spatio-temporal variation characteristics of housing vacancy in shrinking cities, and explore the influence of housing vacancy in shrinking cities of different scales. The main conclusions are as follows: (1) During the study period, the urban shrinkage phenomenon in Northeast China is significant and the housing vacancy rate is on the rise. The housing vacancy rate is generally higher in severe shrinking cities. (2) The configuration of property facilities and the characteristics of the surrounding environment are the main influencing factors of housing vacancy. The level of urban economic development, regional transportation conditions and natural resource conditions have gradually increased their influence on housing vacancy. (3) Improving economic efficiency and increasing residents' income can help alleviate vacancy in slight shrinking cities, while severe shrinking cities need to adjust the level of property facilities and optimize the layout of transportation facilities to reduce vacancy rates.

This study explored spatial characteristics of and spatial relationships between "townization" and transportation advantages in 2460 small towns in the Yangtze River Delta. Bivariate spatial autocorrelation was used to reveal how transportation has impacts on "townization". It is found that: (1) The overall development of "townization" in the study region is in the early to mid-term stages, with over 50% of towns having a "townization" level of less than 30%. There was significant spatial differentiation in transportation advantage, with advantages decreasing from a central point outwards: Shanghai acted as the primary center, Suzhou-Wuxi-Changzhou, Hangzhou, Ningbo, and Hefei were secondary centers, and underdeveloped city outskirts and the border area of Anhui acted as the peripheral layer. (2) The level of "townization" showed a general coordination with transportation advantage, whereas simultaneous low levels of both predominated and coordination decreased with increasing distance from central urban areas. Developed areas, such as Shanghai and Suzhou-Wuxi-Changzhou, contained small towns with developed transportation but relatively low "townization" level. In contrast, underdeveloped areas, such as Northern Jiangsu and Anhui, contained small towns with high population densities despite low transportation advantage. (3) Transportation had a significant positive impact on "townization". (4) While location factors generally promoted "townization", some specific factors had negative impacts. Both positive and negative effects of location factors were more pronounced in more developed areas. Transportation accessibility primarily promotes the transfer of goods and services and technologies between core cities and surrounding towns through spatial spillover, thereby reshaping the economic advantage of small towns and increasing population density. The concentration degree of the road network mainly affects the population density of towns by influencing travel costs and the speed and scale of movement of goods and services.

The quality of development is crucial for China to comprehensively build a socialist modern country. Drawing on related concepts of development in quality, the paper conceptualizes a city in high-quality development and proposes a stylish framework with five dimensions to evaluate it, in line with the New Development Philosophy, which is composed of innovation, coordination, greenness, openness and sharing. Using the methods of spatial analysis, club convergence test and spatial Durbin model, the paper identified the spatial evolution of the quality of city development in China and associated determinants during 2005-2020. On average, the level of city development quality increased by 48.4% during the study period. The number of cities at low-level of quality in development decreased dramatically, accompanied by a profound transformation in the spatial pattern of city development quality, which presents significant spatial aggregation. The spatial imbalance remains for cities with different development qualities, and the challenge is still huge to narrow the gap. With significant role differentiation among cities, a "pioneering-catching up" pattern emerges, and the 11 pioneering cities such as Beijing, Shanghai and Shenzhen have become the pioneers of high-quality development in China. Key determinants for cities achieving high quality in development includes urbanization level, public investment, digital economy, environmental regulation and economic growth, while there is inverted U-shaped relationship between city size and development quality. To achieve the goal of high-quality city development in the new era, it is necessary to focus on the development of cities in the central and western regions, making full use of the demonstration role of pioneers, promoting quantitative growth, strengthening environmental regulations, cultivating the new forms of digital economy, and optimizing the city size hierarchy.

Human society is currently in the stage of significant digital transformation. The basic characteristics and internal mechanisms of human activity systems are undergoing major transitions. In particular, activities in virtual space are becoming diversified and self-systematical, and they more actively and frequently interact with the activities in the physical space in a complex way. At present, research on the digital transformation of human activity system increasingly emphasizes the variation and complexity of the behavior in virtual space. The research also highlights the necessity to go beyond the duality of physical and virtual space and to integrate technological use with activity system. This paper innovatively proposes the concepts of urban virtual space activity system and urban physical-virtual activity system. On the one hand, the new concepts emphasize the characteristics of urban virtual space activity that it increasingly becomes an independent activity system (of urban physical space activity). On the other hand, the concepts focus on the interaction relationships between urban physical and virtual activity systems. The theoretical construction of urban physical-virtual activity system can deepen the understanding of the digital transformation of urban activity system and further provide policy implications. This paper systematically states and discusses the conceptual and research frameworks of urban physical-virtual activity system in the dimensions of theoretical and methodological innovation, empirical topics innovation, and practical innovation. The concept and elements of urban physical-virtual activity system can provide new theories and methods to analyze urban space in digital transformation, and scientific support for urban life circle planning in smart cities and governance of digital life.

As an important part of Chinese modernization, rural modernization is the ultimate goal of rural development and comprehensive revitalization in China. The rural modernization in China has entered a new stage. Based on the connotation and logical relationship of rural development and rural modernization, this paper systematically sorts out the stages, paths, strategies and theoretical evolution of global rural development after World War II, summarizes the problems and challenges faced by rural modernization in China, and constructs the research framework of Chinese rural modernization. The main conclusions are as follows: (1) Rural development aims to promote rural revitalization and urban-rural integration by continuously optimizing the development elements of rural areas and reshaping rural functions and forms, while rural modernization is the process of realizing the modernization transformation of agriculture, rural areas and farmers by gradually changing rural traditional production and lifestyle through concepts, elements and mechanisms of modernization. (2) After World War II, the development focus of global countryside gradually shifted from agricultural revival, rural ecological environment protection and sustainable development to green, eco-friendly and intelligent development of rural areas in the new period, and the theoretical cognition has experienced the transformation from productivism, post-productivism, multi-functionalism to the paradigm of neo-productivism and sustainable development of the global countryside. (3) The rural modernization in China still faces problems and challenges such as backward conditions for agricultural production, insufficient integration of three rural industries, lagging construction of rural infrastructure, hidden dangers in rural social governance, dilemma of rural resources and environment, and shortfalls in rural human capital. (4) Facing the national strategic needs of Chinese modernization, rural revitalization and urban-rural integrated development, the focus is constructing the theoretical framework of Chinese rural modernization from the aspects of institutional system innovation, regulation and planning technical system of rural space, integration and activation path of resources and elements, and future scene construction of smart and green countryside and its scientific governance. Based on the systematic thinking of human-environment coupling, the future research of Chinese rural modernization should deepen the basic theories and scientific paths, development models and guarantee mechanisms, social collaborative governance and spatial regulation and planning to construct the discourse system of academic disciplines in rural geography associated with Chinese rural modernization transformation.

Using Tencent population migration data in 2019 and Chinese language distribution data, the paper reveals the language ties effect of dialect similarity on Chinese population flow, and further explores its spatiotemporal heterogeneity, traffic mode heterogeneity, and the moderated role of spatial distance on its impact. The results show that: (1) Dialect similarity increases the path formation probability and the relationship strength of the inter-city population flow network in China, and forms the language ties effect in the population flow network. Geographic distance and language distance can be regarded as the explicit and implicit spatial costs of population flow, respectively. (2) There are spatiotemporal heterogeneity and traffic mode heterogeneity in the language ties effect. With each unit increase in dialect similarity, the path formation probability of China's population flow network will increase by 47.7% and 49.5%, respectively, and the flow intensity will increase by 17.1% and 9.9%, respectively, in the Spring Festival travel rush and the daily periods. At the same time, there are positive, negative, and degree differences in the influence of the language ties effect on population flow in different language regions and different modes of transportation, revealing the spatial differences and geographical implications of the language ties effect in the process of affecting China's population flow. (3) The effect of language ties is restricted by the law of spatial decay, and shows differences and complexity in different modes of transportation and periods. The paper expands the current research on the influencing factors of China's population flow from the perspective of economic, social and demographic characteristics, helps to understand the driving mechanism of China's population flow, and has practical significance for social governance and cultural diversity protection in multi-ethnic integrated China.

The historical evolution of administrative divisions is an important part of historical geography and political geography. The research of the change process of administrative units is the basis of the history of administrative divisions, and the restoration and analysis of the whole process of the evolution of administrative divisions over a long period of time in history is the basic support for exploring the law and governance ability of local administrative system change. Based on the original historical documents such as the official history and geographical records of past dynasties, this paper combs the characteristics of the long-term evolution process and spatial pattern change of China's county-level administrative units in the past 2200 years (221BC-2021). The research results show that: (1) The number of county-level administrative units in Chinese history generally shows an increasing trend, but the total number is basically stable. The Tang and the Qing dynasties had a large number of counties, reaching two peaks. Since the Ming and Qing dynasties, especially since modern times, the number of county-level administrative units has continued to increase, which reflects the historical process of border development and county system expansion. (2) In the historical period, the scope of jurisdiction (the number of counties under the jurisdiction of administrative units that govern county) mainly shows a shrinking trend. The average number of counties under the jurisdiction of the administrative units that govern county decreased from 21.3 in the Qin Dynasty to 8.5 in 2021. (3) In the past 2200 years, the establishment of county-level administrative divisions shows a trend of spatial expansion, but there was partially inward contraction in the Xijin, Liao, Song and Jin dynasties. The counties in the historical periods mainly started from the middle and lower reaches of the Yellow River and gradually expanded outward. The density of counties within each region continued to increase. (4) The middle and lower reaches of the Yellow River (Henan, Southern Hebei, Shandong and other places) have long been high-density regions with counties. The density of counties in the Chengdu Plain, Guanzhong Basin and Fenhe River Basin is also relatively high. (5) In the past 2200 years, the center of gravity of county-level administrative divisions has changed by about 3° in the north-south and east-west directions, both of which are located to the southeast of the current geometric center of China. The changes in the center of gravity of the county-level administrative divisions in Chinese history is of great geographical significance, which is basically consistent with the migration process of the population / economic center of gravity in the historical periods.