The territorial spatial equilibrium is an important goal of ecological civilization construction and territorial spatial governance. Under the guidance of the “Two Mountains”theory and the theory of strong and weak sustainability, this paper first explores the connotation and state assessment model of the territorial spatial equilibrium based on the division of ecological wealth and material wealth. Secondly, this paper explores the realization mechanism of territorial spatial equilibrium through the analysis of the characteristics difference and interaction mechanism between ecological wealth and material wealth. Finally, based on the evolution analysis of the equilibrium state of the specific territorial space unit, the feasible path to realize the overall territorial spatial equilibrium is studied. The results show that: (1) The connotation of territorial spatial equilibrium based on two kinds of wealth is the double convergence of per capita material wealth and per capita ecological wealth in space, and each space converges to an ideal level. (2) There will be four situations of "one equilibrium and three disequilibria" in the overall state of territorial spatial equilibrium. The key to realize the territorial spatial equilibrium is to promote the positive interaction between the two kinds of wealth, enhancing the synergy effect and reducing the trade-off relationship. (3) The equilibrium state of territorial space unit can be divided into four types: lower equilibrium or overall disequilibrium, development disequilibrium, ecological disequilibrium and coordinated equilibrium. Promoting the evolution of each specific territorial space unit to a higher-order equilibrium state is a feasible way to achieve overall territorial spatial equilibrium. Following the interaction mechanism of the two kinds of wealth and the equilibrium state evolution law of the territorial space unit to guide the development and protection of specific territorial space units is conducive to achieving the overall territorial spatial equilibrium.
Based on an analysis from a “breakdown historiography” perspective, research on the adjustment and its extreme form closure of geography departments aims to reveal the identity problems that geography and its institution have been facing. After reviewing extant literature that mainly focused on the adjustment of geography departments worldwide, this study analyzes the causes and influences of the adjustments of geography departments with a focal point on the Anglophone and Chinese geography. Further, it aims to enlighten and encourage geographers to take action in promoting the development of healthier geography departments. The result shows that although there are many differences among forms of adjustment of geography departments, such as frequency, magnitude, and processes, “closure” does not imply the end of the discipline, general adjustment can even promote the place of geography in universities, whereas adjustment indeed has many adverse effects on the study of geography, the identity of its institution, and its reproduction as a scientific and consistent university discipline. Particularly, human geography was considered a non-scientific subject and is now viewed as a diversified part of geography that influences disciplinary imagination. The causes and impacts of the adjustment of geography departments are complex, which shows that geography needs to strive for survival and development. Considering the nature of geography and the trend of contemporary geography departments, the study concludes that geographers need to invest in collective “inward” and “outward” efforts to promote the discipline and the complete identity of its institution. An alternative strategy is making geography and its institution an interdisciplinary paradigm that is recognized not only by geographers but also by university administrators, researchers engaged in other disciplines, and the public at large. In doing so, geography can be shaped as an important interdisciplinary unit that, through greater competitiveness and as a complete institution, forms a symbiotic relationship with other disciplines in universities.
Lake shoreline morphology is an important dimension to describe and quantitatively express the spatial distribution characteristics of lakes. In recent years, affected by climate warming and humidification, lakes in the interior drainage area of the Tibetan Plateau generally showed a rapid expansion. The dynamic changes of lakes are reflected in lake hydrological parameters, including area, water level and water volume, and cause significant changes in lake morphology. Based on multi-period lake distribution data, we construct a quantitative index system of lake shoreline morphology by combining the fractal and landscape ecology theory, and quantitatively analyzes the spatiotemporal variation characteristics of lake shoreline morphology and its influencing factors in the interior drainage area of the Tibetan Plateau since 1990. The results show that: (1) In the last 30 years, the fractal dimension and shoreline development index of lakes in the study area have shown an increasing trend, while the circularity ratio has shown a decreasing trend during this period, and the aspect ratio has not changed significantly. (2) The overall characteristics of lake shoreline are determined by geological structure. The lake shoreline and its changes in the fault lake area are obviously more complex than those in the depression lake area. The rangeability of lake shoreline in the area roughly descends from northeast to southwest, showing spatial auto-correlation in the Hoh Xil region, and central and southeastern Qiangtang Plateau. (3) There is a certain correlation between the change of lake shoreline and the change of lake area. When the lake is in the state of expansion, the fractal dimension and shoreline development index of the lake will increase, and vice versa. (4) The variation of the lake shoreline is affected by the landforms around. In the area with a large drop of lakeside terrain, the lake shoreline is relatively stable and the change speed is low. The variation of shoreline has a power function relationship with the average elevation difference in the buffer zone of 1 kilometer around the shoreline. This study reveals the change patterns and influence characteristics of lake shoreline morphology in the interior drainage area of the Tibetan Plateau under the influence of climate warming and humidification, discusses the relationship between the shoreline and its change pattern and the geological structure, climate and hydrology, modifies the methods of studies on dynamic change in lakes, and provides a new scientific perspective for thoroughly understanding the response of the Tibetan lakes to climate change and monitoring the impact of lake changes on hydrogeomorphic features.
Land surface temperature (LST) is an extremely important geological parameter in the study of the process of terrestrial environmental interaction, and its spatio-temporal differentiation is closely related to the attributes of the underlying surface and the topography and geomorphology pattern. Based on MOD11C3 data from 2000 to 2020, this paper uses GIS spatial analysis, spatial center of gravity model and improved radius method to study the distribution characteristics and changing trends of LST on the spatial and temporal scales of the month, season, year, day and night sequences in Xinjiang, and with the help of multi-source remote sensing data such as LUCC and DEM, we further explore the geographical characteristics of various underlying surfaces, different geomorphic units and some typical areas of LST vertical decline rate, temperature increase and decrease, and urban heat (cold) island effect. The results show that: (1) during the study period, the average annual LST in Xinjiang was 9.45 ℃. The areas with decreasing temperature and increasing temperature accounted for 13.3% and 86.7% of the study area, respectively. So in the past 20 years, the study area showed an overall warming trend (0.024℃·a-1), which was about 0.01 ℃·a-1 higher than that of the whole country. The largest increase was observed in spring, followed by winter; the change of LST at night was significantly stronger than that in the daytime. The temperature differences between day and night in both spring and summer are greater than 23.7 ℃, and the smallest temperature difference is in winter (about 15 ℃); the interannual high and low temperature centers of gravity migration trajectory in the study area is mostly distributed in the area with large LST variation, and the spatial distribution of LST and the centers of high and low temperature in each month The transfer trajectories all showed strong symmetry during the year with July as the midpoint. (2) The spatial distribution of the hot and cold environments on different underlying surfaces is significantly different. Among them, the unused land dominated by deserts and bare soil has the highest average annual LST (13.42 ℃) and the largest day-night temperature difference (23.6 ℃). The glaciers in alpine regions have the lowest annual average LST (-7 ℃) and the lowest day-night temperature difference (14.3 ℃). The average annual LST of other underlying surfaces is between 2.6-11 ℃, and the temperature difference between day and night is small and consistent (average 16.75 ℃). (3) The east-west trending of “three mountains and two basins” geomorphic structure greatly makes the latitude zone of Xinjiang LST less stable. The vertical decline rates of LST in the mountainous areas (groups) of the study area are not the same. The LSTs of the Altay Mountains at higher latitudes vary (0.63 ℃/100 m), followed by the Pakakun's Group with high mountains (0.57 ℃/100 m), and the Tianshan Mountains (0.54 ℃/100 m). In addition, various degrees of temperature inversion occurred in the foothills of the mountainous areas (groups), and the linear fitting effect of the LST vertical decline rate at the mountainside was the largest. (4) Most of the typical cities selected in this study show different degrees of urban heat island effect. Among them, Urumqi city has the strongest urban heat island effect, followed by Yining city, while Hami city is the weakest; Aksu city exhibits the oasis urban cold island effect, but the urban heat (cold) island effect of each city has a certain number of rings (8 rings) about urban heat (cold) island footprints. The research results can provide theoretical support for soil development and protection, regional agricultural production and planting, urban engineering construction, as well as production and life in Xinjiang.
The atmosphere is not only an important part of the earth's natural environment, but also a basic resource for human survival. As air pollution and climate change have been the major global concern, traditional concepts such as air pollution can not fully reflect the overall function and particularity of the atmosphere, so this paper proposes the concept of atmospheric security. By analyzing the atmospheric ecosystem services, we construct a theoretical framework of atmospheric security. Finally, the framework is applied to the comprehensive evaluation of the “2+26” cities in the Beijing-Tianjin-Hebei region and its surroundings. After summarizing the characteristics of sub-dimensions and sub-regions of atmospheric security, we offer relevant proposals for the local governments in order to identify the key areas of atmospheric pollution control.
At present, the trend of technology sovereignty and anti-globalization of science and technology is gradually emerging. The world has entered the era of science and technology geopolitics. The core sources of state power have evolved from military strength in the colonial era to economic strength in the era of trade, and to scientific and technological strength in the era of knowledge. Science and technology power has become the focus of the game among big powers. In the international environment where technology is currently targeted and blocked, how to depict the spatial pattern of power of China and the United States on a global scale and find the key space for breaking the technological blockade are both realistic topics and hot directions in an urgent need of research. Based on the theory of interdependence between countries and the theory of balance of power, this study used sensitivity and vulnerability indexes to establish a static comparative model of trade power of high-tech products, and dynamically depicts the change process of the space and balance of power of science and technology between China and the United States since we entered the new century. Results indicate that: (1) the global map of science and technology power was restructured rapidly. The center of science and technology power moved eastward systematically, which was evolving from the pattern of the US monopole to the situation driven by Sino-US dual cores, that the two sides changed one after another in the game of science and technology power, and finally formed a pattern of East-West coexistence. (2) China's scientific and technological power space rapidly expanded from the surrounding areas to the countries along the Belt and Road. China's spaces of science and technology power rapidly expanded in the surrounding areas, while those of the US shrank significantly, although it still occupied a leading position. (3) Countries in the Sino-US economic equilibrium zones shifted to developed countries and the innovative resource endowment countries, especially European countries, who were important partners in China-US high-tech industry competition. Electronic technology and optoelectronic technology are the focus areas of Sino-US game.
Under the background of deepening economic globalization and global industrial transfer, different countries have different positions in global value chain (GVC) in international division of labor production. Whether a country can benefit from participating in globalization increasingly depends on its successful integration into global value chains and its competitive advantage in a particular segment. It is of great theoretical value and practical significance to clarify the GVC status of global manufacturing power and to understand its international division of labor and its influencing rules. This paper uses TiVA database to calculate the GVC status index and analyze its evolution characteristics of 59 countries and regions in the world from 1995 to 2014. The results show that the countries with high GVC status are mainly distributed in America, Europe and East Asia, and the countries in Central Asia, West Asia, Africa and Oceania have little participation. In recent years, the high value-added production links have been increasingly concentrated in a small number of countries. Most countries have a high position index in labor-intensive industries and a low position index in technology-intensive industries. The added value of technology-intensive industries is obtained by a few countries that master core technologies and both ends of the value chain. From the perspective of sub-sectors, the core countries and regions have shown the characteristics of staged evolution. In terms of spatial correlation, both the overall manufacturing industry and the labor-intensive industry GVC status index show significant spatial agglomeration characteristics, and the degree of agglomeration first decreases and then increases, and the spatial agglomeration distribution of the GVC status index for capital-intensive industries is most significant, which has been continuously strengthened, while the spatial agglomeration effect of the GVC status index of technology-intensive industries is not obvious. In terms of spatial agglomeration, the GVC status index of most countries is low, and the added value of trade is obtained by a few countries with higher GVC status. In addition, foreign direct investment and capital investment can restrain the improvement of a country's GVC status, scientific research and innovation ability can promote the improvement of a country's GVC status, export scale and a country's GVC status have a significant positive relationship, institutional quality has no significant impact on a country's GVC status. However, institutional quality will promote the inhibiting effect of foreign direct investment on GVC status.
Based on data drawn from the Web of Science and a selection of 526 major world cities in line with the world city network research related with advanced producer services, this paper performed multiple spatial and network analyses to examine the evolution of structural features and driving factors of the global interurban knowledge collaboration network. The results show that: (1) the spatial structure of the top cities of the network, which are mostly in Europe and US, has remained stable. The spatial configurations of the centers of global innovation and global production services are different. The connectivity of cities is unevenly distributed across different geographical scales, with a clear west-to-east and north-to-south shift. (2) In terms of topological structures, the scale, density, and connectedness of the network have increased over time. The network exhibits small-world and scale-free features, and presents significant “core-periphery” and “community” structures. Cities differ in their national and global functions. (3) The evolution of the global interurban knowledge collaboration network is influenced by both endogenous and exogenous driving factors. Endogenous driving factors include the shifting paradigm of contemporary knowledge innovation, the non-linear development paths of knowledge innovation, the unique modes of knowledge combination, the “preferential attachment”, and the social interdependence of maintaining knowledge collaboration. Exogenous driving mechanisms include geographical proximity, country borders, regional agreements, and colonial histories.
Industrial agglomeration is conducive to the formation of specialized production processes and labor market, sharing infrastructure, which can promote the high-quality development of urban economy by giving full play to the externality of agglomeration economy and improving the degree of market competition. Based on the panel data of 278 cities in China from 2005 to 2018, this study adopts SBM-DEA model to measure the high-quality economic development and analyses the spatial distribution of industrial agglomeration by GIS. It then establishes a spatial Durbin model to deeply analyze the relationship between industrial agglomeration and the quality of urban economic development. The main findings are as follows: (1) Industrial agglomeration has significant positive direct effect and spatial spillover effect on the improvement of economic development quality, and the opening of high-speed railway amplifies the promotion effects. (2) Manufacturing industry and producer services agglomeration have different effects on the quality of economic development. The former has more direct effects on the quality of economic development and the latter has more spatial spillover effect. The scope of producer services may be larger, which is not only conducive to the transformation and upgrading of the local manufacturing industry, but also may promote the economic quality of nearby cities through industrial linkage and spatial spillover. (3) The cities in eastern China are more dependent on the agglomeration of producer services, while the cities in the central and western regions depends more on manufacturing industry, and the level of industrial development, so their spatial spillover effect is low. (4) The spatial spillover effect of producer services agglomeration in big cities is significantly higher than the direct effect. Producer services agglomeration in medium-sized cities plays a limited role in regulating the promotion of manufacturing agglomeration. The impact of industrial agglomeration in small cities on the quality of economic development is weak as a whole, which is largely dependent on the governments' financial expenditure on science and technology.
Existing research on strategic coupling has addressed the interaction mechanism between strategic coupling and regional industrial upgrading under globalization. However, current studies are mainly based on qualitative research and lack of quantitative measurement of relationships between strategic coupling and industrial upgrading. Therefore, based on two dimensions, the enterprise and the region, this study constructs an analytical framework to explore the patterns of industrial upgrading under the influence of strategic coupling. This study also adopts a multiple linear regression model to verify the impacts of strategic coupling on industrial upgrading. The main conclusions are as follows: First, all cities in the Pearl River Delta (PRD) have undergone industrial upgrading. However, there are some intra-regional divergence considering the patterns and extent of upgrading. Among these cities, Shenzhen has shown the best performance of upgrading, an overall regional upgrading. Guangzhou and Zhuhai have less-best upgrading, enterprise upgrading, which is followed by Dongguan with an upgrading related to industrial structure. Significantly, the phenomenon of involution has not yet occurred in the PRD. Second, the difference in the patterns of strategic coupling affects the process of industrial upgrading significantly. The production dependency on Hong Kong, Macao and Taiwan-invested enterprises, and the technological dependency towards foreign enterprises are the most prominent influencing factors. Third, after the 2008 financial crisis, the interaction mechanism between strategic coupling and industrial upgrading has changed apparently, which remarked a turning point in the path of regional development. Regions that have higher dependency towards Hong Kong, Macao, Taiwan and other general foreign enterprises on industrial production have lower speed of upgrading. However, regions where Hong Kong, Macao and Taiwan-invested enterprises have higher technology have more prominent regional upgrading. Nevertheless, the influence of advanced technologies brought by foreign-invested enterprises in fostering regional upgrading have faded out. Overall, this paper helps to advance the theory of industrial upgrading under globalization. It also tentatively explores the use of quantitative methods in relational economic geography.
The reconstruction and study of the Southern Silk Road's transport network can improve our understanding of the economic and trade development in regions on the frontier of southwest China and borders among China, Southeast Asia, South Asia, and other historic regions. Furthermore, it would strengthen the cultural exchange and cooperation among these regions. In this paper, a section of the transport network of the Southern Silk Road within China is reconstructed on the basis of historical documents, historical geography research papers, field survey data, contemporary transportation and remote sensing image data, DEM data, etc. The reconstruction focuses on four periods: (1) Han Dynasty to Jin Dynasty, (2) Tang Dynasty to Song Dynasty, (3) Yuan Dynasty, and (4) Ming Dynasty to Qing Dynasty. The human and natural factors that influenced the direction of transport routes in ancient mountainous areas of southwest China are analyzed, the ancient transport mileage and measured distances are compared, and the proportional relationship between them is studied. The results are as follows. First, the transport network between Sichuan and Yunnan on the Southern Silk Road was formed during the Han and Jin dynasties and has remained relatively stable for the past 2000 years. In addition, the transport network within Yunnan and the outbound routes passing through Yunnan exhibit a more diversified development trend. Second, human factors such as changes in the degree of administrative power that the central government could exercise over the minority areas in China's southwest border played an important role in the overall pattern and spatial evolution of the Southern Silk Road transport network in different periods throughout the history. Third, an altitude of 2200 m and a slope of 20° are important threshold values for natural factors affecting the direction of the transport routes of the Southern Silk Road. Meanwhile, 1 li, an ancient distance unit in the mountainous area of southwest China, equals to 0.45 km.
Poverty and getting rid of poverty are the starting point and power source of China's reform and development path. Targeted poverty alleviation in China has made remarkable achievements. By the end of 2020, 98.99 million rural poor people had been lifted out of poverty under China's current standards. The implementation of the targeted poverty alleviation policy has completely solved the problem of absolute poverty in China, which has also made great contributions to the poverty reduction in the world. Based on the multi-dimensional poverty theory, from the micro perspective, through the construction of the theoretical framework system of the effectiveness of poverty alleviation, we carry out the research on the spatial differentiation and influence mechanism of the effectiveness of poverty alleviation, which is of important academic value and practical guiding significance to enriching the theoretical system of rural poverty research. The paper selects 21 indicators from 4 aspects of economic construction effectiveness, infrastructure and public service facility construction effectiveness, life security and employment security effectiveness to examine the spatial pattern and influence mechanism of Xinhuang County's poverty alleviation effectiveness in 2019. It can be shown that: (1) There are relatively small differences between the economic construction effectiveness and life security effectiveness in the 84 villages in the study area that have been lifted from the poverty list, with high-efficiency areas, relatively high-efficiency areas, and general-efficiency areas being alternately distributed. The effectiveness of basic and public service facilities construction and employment security is characterized by obvious spatial differentiation. (2) The comprehensive poverty alleviation effectiveness of the 84 villages in the county presents a pattern of “high in the east and low in the west” in space, which has a strong correlation with the terrain. (3) The main influencing factors of the comprehensive poverty alleviation effectiveness are the proportion of people out of poverty who suffer from serious diseases and long-term chronic diseases, the distance from the administrative village to the county seat, the age structure, percentage of households with average income higher than the county's level, and the status of the labor force. The foundation of village development and the natural elements are the fundamental factors affecting the effectiveness of poverty alleviation. The population structure of the village is the vital factor affecting the spatial distribution of poverty alleviation, and the development potential of the hamlet is the continuous driving force to consolidate the effectiveness of poverty alleviation.
Socio-spatial segregation is a critical issue of urban studies. With the increase of human mobility, the traditional measurements of residential segregation based on aggregated data show limitations. Few studies have explored the segregation in residents' daily activity space outside their living spaces, or the spatiotemporal patterns of segregation level in different periods of a day. Thus, it is necessary to study the individual-based socio-spatial segregation in various geographic and temporal contexts. Using data from a household travel survey in 10 typical towns of the suburbs of Shanghai in 2017, this study researched the spatiotemporal characteristics of household registration segregation in people's daily life based on a creative individual-based proximity index, which measures the proximity of various groups in different geographic contexts with various activity types and time periods. We divided a day into eight periods and used the i-STP index to measure the spatiotemporal pattern of segregation of four kinds of household registered residents. By dividing Shanghai into hexagonal grids with an actual area of 5 km 2, the average value of i-STP within each grid was calculated. Then Arcscene 10.2 was used to visualize the results. Results show that the average i-STP is higher in work activities during weekdays and is lower in recreation activities on weekends, indicating the distinctions of segregation levels in different activity contexts. Results also show that lower i-STP is detected during commuting time (6:00-9:00) and leisure time at night (18:00-21:00) on weekdays and the average i-STP reaches the minimum in the afternoon (15:00-18:00) on weekends. We also found that residents with different household registration types have different spatiotemporal segregation patterns and that the working place and activity place of residents in day time shows higher segregation level than the living place at night. The study provides a new measure of segregation from an individual-based and dynamic perspective, which can fill the gap in the existing research on segregation based on activity space. The results of the study indicate that attention should be paid to the segregation of different types of registered population in work and leisure activities in large cities of China to enhance the interaction between different groups.
The spatial balance of educational resource distribution is related to social equity. Existing studies mainly focus on formal educational facilities, such as primary and secondary schools, but pay less attention to children's education and tutoring institutions. As the phenomenon of education and training becomes more frequent, its influence on urban spatial functions and social equity becomes increasingly prominent. Therefore, it is necessary to further analyse the spatial clustering characteristics and influencing factors of children's education and tutoring institutions. Based on the POI data of children's education and tutoring institutions in Beijing in 2018, this paper first uses spatial analysis methods, such as kernel density and Moran's I index, to examine the spatial agglomeration characteristics of these institutions. The spatial agglomeration factors were analysed by building a grid and using the multiple regression method. The results show that the children's education and tutoring institutions in Beijing are clustered in a semicircular agglomeration zone extending northward from the Second Ring Road to the Fifth Ring Road. Subject-type institutions are more concentrated in Haidian District, while art-type institutions are mainly found in Chaoyang District. These institutions have different spatial clustering characteristics at different scales. The spatial clustering distribution of the institutions in urban Beijing is the result of the comprehensive effect of many factors, such as school district, interindustry agglomeration, housing price, transportation convenience and population situation. There are significant differences in the leading factors of agglomeration of education and tutoring institutions in different disciplines and at different scales. The results show that extracurricular education resources tend to gather in key school districts and high-level communities, which may aggravate the spatial imbalance of education resources. This study helps clarify the interaction between education space and urban space and the role of the education and training industry in the construction of the urban spatial structure and promotes the equity of children's education and the balanced distribution of educational facilities.
There are some studies examining the effects of residence-based air pollution using fixed-site monitoring station data on long-term wellbeing. However, research on the relationships between real-time air pollution exposure based on space-time behavior and activity satisfaction have been very scare so far. Based on real-time data collected by portable air pollutant sensors in Beijing in 2017, this study measures the real-time air pollution exposure across various activity attributes and socio-economic variables, and investigates the spatiotemporal distinction of activity satisfaction. Furthermore, this study employs structural equation model to analyze the effects of socio-economic attributes, space-time behavior and real-time pollution exposure on residents' daily activity satisfaction. Results show that there are significant differences of real-time air pollution exposure between social groups, mainly due to their different space-time behavior and microenvironments. The direct effect of objective air pollution exposure on activity satisfaction is insignificant, while subjective evaluation on air pollution has a significant and direct effect on activity satisfaction. However, the real-time air pollution exposure has a significant direct effect on subjective air exposure and a significant indirect effect on activity satisfaction. This indicates that objective air pollution negatively affects activity satisfaction indirectly by influencing perceived air pollution. Moreover, air pollution could mediate the relationships between socio-demographic variables and activity wellbeing; for instance, it could significantly lower the activity wellbeing for residents with primary education status.
Based on the 2001-2019 million-ton mortality rate by province, this paper conducts a quantitative study on the degree of spatial variation of China's coal mine safe production level and its driving factors using the Theil index, coefficient of variation, and geographic detectors to provide support for identifying risk level of regional coal mine safety in time and strengthening accurate coal mine accident warning and prevention. The results show that: (1) Based on the million-ton mortality rate, China's coal mine safe production level can be divided into five regions: Southern Region (Sichuan, Yunnan, Chongqing, Guizhou, Hunan, Hubei, Guangxi, Jiangxi, Guangdong, Jiangsu, Zhejiang and Fujian), Northeast Region (Heilongjiang, Jilin and Liaoning), Northwest Region (Qinghai, Xinjiang and Gansu), Northern Region (Beijing, Hebei, Shandong, Henan and Anhui) and North-Central Region (Shanxi, Shaanxi, Inner Mongolia and Ningxia). (2) The difference in coal mine safety level experienced three stages: the period of overall stability and differential equilibrium (2001-2007), the period of overall and differential fluctuant rising (2008-2015), and the period of overall stability with increasing interval differences (2016-2019). After going through these stages, the overall difference in coal mine safety level still maintained a slow-growth trend, and the differences within regions began to shrink but the differences between regions continued to expand. (3) The factors affecting the safety level of the five regions are different. The extractive environment has a large impact on the northeast, northwest and southern regions; changes in the supply and demand situation and enterprise management indicators are more likely to cause changes in the safety level of the northeast, northern and north-central regions; the regulatory and monitoring indicators have a great influence on all the regions except the north-central region; the million-ton mortality rate of each region has the response to the economic environment, and the influence coefficient of the indicators is at medium level. (4) The indicators of regulatory monitoring, supply and demand, and the economic environment generally have a strong non-linear enhancement effect, which is more likely to affect the change of safety level by adjusting the indicators of regulatory monitoring.
After more than 40 years of reform and opening up, the mobility of domestic labor floating population in China has generally shifted from individual migration to family migration. Existing studies suggest that the urban life of the floating population mainly revolves around the place of employment and residence, and that they tend to live in place as close as possible to their working places if the rent is acceptable. With more family migrations, some complex factors need to be considered in the residence and work place decision-making of the floating population, as these factors will lead to the change of jobs-housing relationship. Based on the residents' daily travel survey data of Guangzhou, this study investigates the characteristics of the jobs-housing relationship of the floating population, and the differences of the jobs-housing relationship between family migration states, and makes comparison with that of the registered local citizens. The results reveal that the average distance between housing and working place of the floating population is significantly shorter than that of the registered local citizens, showing obvious proximity. However, as family migration increases, the jobs-housing distance of the floating population has gradually increased to a comparable level to that of the registered local citizens. The increase of the jobs-housing distance is most obvious from moving alone to couple migration, mainly because it is difficult for both husband and wife to realize jobs-housing proximity. The increase in the jobs-housing distance caused by the accompanying migration of children and the elderly is relatively small, but the suburbanization of work and residence is obvious, because the suburbs can meet the family's requirements for better housing and residential environment at a lower cost. As family migration becomes more and more common, the jobs-housing relationship of the floating population will gradually converge with that of the registered local citizens. But there are still substantial differences behind the convergence. Most of the family-migrating floating population tends to rent house, showing strong instability. Policy makers should pay attention to the coexistence of their needs for both lower rent and better environment.
