Analyzing the evolution characteristics and key influencing factors of the spatial pattern of the United States at the national scale provides an experiential reference for the improvement of China's territorial spatial planning system in the new era. The results show that: (1) Urban expansion, agricultural production, water ecological protection, and bare land management are the main trends in the evolution of the spatial pattern of the United States from 2001 to 2019. Especially, large-scale and high-growth urban expansion is still a prominent feature of the United States, where the urban area has remained at 8.80% for nearly 20 years. At the same time, agricultural production efficiency in spatial areas has significantly increased. (2) Unlike the final evolution result of the rapid expansion of urban areas, the large-scale mutual transformation between agricultural and ecological spaces is the dominant transformation characteristic within the spatial pattern of the United States. A profound spatial layout adjustment is taking place between "cropland-animal husbandry-forestry". While promoting agricultural expansion and improving production efficiency, land management and ecological environment optimization, it has also led to large-scale loss of green space. (3) Geographical conditions, infrastructure construction, land development policies, natural disasters, and regional basic characteristics are the dominant driving factors of the spatial evolution of the United States in the past 20 years. At the same time, changes in hydroclimate conditions such as precipitation, temperature, and humidity have played a key promoting role. Population, economy, and industry have only had a partial impact on the internal development space of urban areas, and have not had a significant impact on the overall spatial changes of the United States. Based on the above conclusions, the article proposes the following suggestions: pay attention to the dynamic impact of long-term climate change on the spatial layout of agriculture and ecology; focus on the differences in the allocation of parameters for urban spatial expansion among different levels and regions; prevent the degradation of agricultural space in traditional grain-producing areas, and construct policies and suggestions for the elastic connection path between bare land management, major land projects, and the territorial spatial planning system.

Africa, as one of the regions with significant political instability in the world today, experiences ongoing armed conflicts that have a serious impact on the peace and stability of the region and the international situation. Based on data from three types of armed conflict points in the 54 countries of Africa, a study was conducted on the spatiotemporal distribution patterns of armed conflicts in Africa from 1989 to 2021, using statistical analysis, kernel density, average center, and hotspot analysis methods. The results are as follows:(1)From 1989 to 2021, armed conflicts in Africa showed a trend of increase, decrease, and then increase again, exhibiting an overall "U-shaped" development pattern. At the same time, the number of conflicts is on the rise, with the hierarchy of conflict types being state armed conflicts > one-sided violent armed conflicts > non-state armed conflicts;(2)The spatial distribution characteristics revealed by kernel density analysis show that armed conflict outbreak points in Africa roughly form a "three" pattern from North Africa to South Africa. The main concentration of armed conflict outbreaks is along the Mediterranean coast, the region around 10° north and south latitude that crosses the equator, and the southern region of Africa;(3)The migration of armed conflict centers in Africa is mainly concentrated in the central region of Africa, intersected by the equator. The migration path of the centers includes the Democratic Republic of Congo, Chad, South Sudan, and the Central African Republic;(4)In terms of the distribution of hotspots and cold-spots, the high concentration of armed conflicts in Africa is mainly found in the central region, the northern part of North Africa, and the northern part of East Africa. The relatively low-conflict areas are mainly located in the western part of West Africa, the southern part of Central Africa, the southern part of East Africa, and South Africa.

Democratic Republic of Congo has sizeable development potential with abundant resources and energy in Africa, but it is subject to the negative impact of armed conflicts for a long time. Taking the armed conflicts of DRC from 1992 to 2021 as the research object, this paper comprehensively uses GIS models including standard deviation ellipse, nearest neighbor index, kernel density estimation and multi-distance spatial cluster analysis to comb the spatial pattern and evolution characteristics of the armed conflicts in the DRC. The results show that the armed conflicts in the DRC have always presented the spatial characteristics of agglomeration in the past 30 years. From the perspective of spatial structure change, the spatial pattern of armed conflicts in the DRC has changed from "one belt, six cores" to "one belt, one core", with North Kivu, Ituri and South Kivu provinces as the core. From the perspective of spatial agglomeration degree, the scope of armed conflicts in the DRC has been reduced, but the agglomeration degree has been increasing. From the perspective of spatial diffusion direction, the diffusion direction of the armed conflict in the Democratic Republic of Congo has changed from "east-west" to "northeast-southwest", showing a significant directivity in the spatial diffusion direction. This paper also argues that geography, resources, society and international factors are the primary causes of armed conflicts in the DRC.

As the global climate warms, the sea ice in the Arctic region is rapidly melting at an unprecedented and unpredictable rate. The economic, resource and strategic value of this region is becoming more and more prominent, and more and more countries are turning their attention to the Arctic, geopolitical issues in the Arctic continue to heat up. In this context, based on the GDELT database, this article uses methods such as mathematical statistics, stratigraphic constrained clustering, and social networks to study the geographic relationship between countries in the global Arctic-related incidents from the second quarter of 2013 to the third quarter of 2022. The results show that: ① During the study period, the cooperation-conflict events among countries in the global "Arctic-related" incidents can be divided into two stages. Compared to the first phase, the second phase saw a decrease in the attention of countries to the Arctic, where cooperation still dominates ②The global network of geopolitical relations between countries involved in Arctic-related events presents a "core-periphery" structure centered on the Arctic countries. As China, the United Kingdom and other Arctic Council observer states pay more attention to the Arctic and participate extensively in affairs, their network status has improved; ③The geopolitical relations between countries in the global Arctic-related incidents have shown a good development trend, but Some of these countries have unequal geographical relations with other countries, especially Russia and other countries; ④The economic, resource and strategic value of the Arctic are prominent, the influence of the geopolitical environment, the increasing militarization of the Arctic region, and the concept of environmental protection in the Arctic have potential effects, promote the evolution of geopolitical relations among countries involved in the global "Arctic-related" incidents.

Benefiting from the guidance of scientific thinking, the diplomatic promotion of the head of state and the support of planning policies, China's concept of participating in Arctic governance cooperation has been continuously enriched, its ability has been continuously improved, and its international influence has been continuously expanded. The policy objectives of understanding, protecting, utilizing and participating in Arctic governance have been continuously implemented. After the outbreak of the Ukrainian crisis, the geopolitical and economic situation in the Arctic has undergone major changes, and multilateral cooperation mechanisms such as the Arctic Council are facing challenges. The trend of internalization of Arctic governance and the globalization of Arctic interests are intertwined. China's further participation in Arctic governance cooperation faces both a series of opportunities and challenges. We should accurately grasp the regular characteristics of the changing situation in the Arctic, combine safeguarding the common interests of all mankind with implementing China's Arctic policy, strengthen communication and cooperation with relevant parties in the fields of energy development, waterway management, scientific investigation and ecological protection, constantly explore new areas and opportunities for cooperation, actively build a blue partnership, promote the "Polar Silk Road" to achieve more positive results, and contribute more China's strength to promoting the sustainable development of the Arctic region.

The development of pharmaceutical products and foreign trade cooperation are facing more and more serious challenges under the intertwined influence of emergencies such as the reshaping of the international value chain and COVID-19 infection. Based on the foreign trade data of Chinese pharmaceutical products, using the trade complementarity index and panel regression model, this paper studied the space evolution and influencing factors of the trade structure of Chinese pharmaceutical products from 2001 to 2021. The results show that the scale of foreign trade "starts low and grows fast", the trade deficit continues to increase, antibiotics have the most comparative advantages, and hormones have the most comparative disadvantages; In terms of spatial pattern, Chinese imports and exports are highly dependent on developed countries and regions in Europe and north America. Developing countries or regions also play a part in Chinese export. In terms of the impact mechanism, the gross domestic product, innovation input and output, aging and multi-dimensional proximity of trading countries are positively correlated with Chinese pharmaceutical product trade, and the degree of regional stability is negatively correlated with it. The impact of foreign direct investment is not significant. At the end of the article, the author provides relevant suggestions for the development of Chinese pharmaceutical industry from the perspective of trade market.

China's economy has changed from high-speed growth to a high-quality development stage, foreign trade plays a crucial role in high-quality economic development. Constructs a three-level evaluation system for the development of foreign trade, calculates the foreign trade of high-quality development level from 2006 to 2019, and empirically tests the dynamic effect of outward foreign direct investment on the high-quality development of China's foreign trade by systematic GMM, research find: First of all, current and previous OFDI can significantly promote the high-quality development of foreign trade; Secondly, the regression results of different economic regions show that the current and last period OFDI of eastern and western regions has a significantly positive impact on the high-quality development of foreign trade, central region was mainly reflected in the last period, northeast mainly reflected in the current period; Thirdly, OFDI of the "Belt and Road" provinces can significantly promote the high-quality development of foreign trade in both the current and the last period, while OFDI of non-provinces only promotes in the last period; Fourthly, before implementation of the "Belt and Road", China's OFDI of 31 provinces only had an impact on the high-quality development of foreign trade in the last period, after implementation both current period and the last period had a significant promotion effect; Fifthly, it is found that both current and last period OFDI of promote the high-quality development of foreign trade through the transmission mechanism of the quality of economic, last period OFDI can promote the high-quality development of foreign trade through reverse technology spillover and labor cost.

Based on multivariate data such as the Baidu index, mileage data, and co-authored paper data, a multi-city network was constructed, then social network analysis was used to explore the evolution characteristics of multi-city network structure in the middle reaches of the Yangtze River from 2011 to 2019, and the QAP model was used to analyze its influencing factors. The results show that: (1) The density of multiple networks in the middle reaches of the Yangtze River from 2011 to 2019 is less than 0.5, but the relationship between cities has gradually becoming closer. In addition, the "small world" characteristisc of each network is obvious, and the hierarchical structure of urban nodes conforms to the rank-size distribution characteristics. (2) The diversity of multiple network structures is obvious, the core skeleton of the information network has not changed significantly, while the change of the economic network skeleton is obvious, the traffic network gradually presents an H-shaped structure, and the innovation network tends to be flat and complex. (3) The centrality of city nodes in the multi-city network has obvious differences. Wuhan, Changsha, and Nanchang are stable network hubs, and the urban agglomeration in the middle reaches of the Yangtze River forms four condensed subgroups, which are mainly related within subgroups. (4) There are strong similarities and differences among multiple networks. Spatial proximity, administrative relationship, level of economic development, and intensity of policy intervention have significant effects on the structure of multiple networks to different degrees.

With the compression of spatial and temporal distance, the actual service population has increasingly become a new category of territorial spatial planning, urban planning and management response. Based on the town-ness and city-ness perspective of the central flow theory, we refined the systematic concept of the actual service population, constructed the framework system for estimating the actual service population, and took 35 metropolises as examples to research the scale structure and spatial-temporal characteristics. The conclusions are as follows :(1) The actual service population should be the average daily population in need of transportation, municipal, commercial and other basic urban services and administrative management in the city, including the permanent population living in the local area for more than half a year and the short-term visitor in the city where the local stay is ' more than one day and less than six months. (2) Integrated traditional statistical data such as population, tourism, transportation and Tencent migration data, took the differentiated demand of population for urban services as the breakthrough point, taking the demand of the permanent population as the benchmark, and converting the short-term visitor into the permanent population, a full-aperture population measurement framework system for the actual service population was constructed. The actual serving population coefficient of 35 metropolises was between 1.09 and 1.36, with an average of 1.19. (3) The annual change of the short-term resident population in China presents the spatiotemporal characteristics of "M" shape annual change and megalopolis directivity, while the inter-city short-term resident population presents the daily change and holiday characteristics of "big wave peak, small sawtooth" shape. This population flow presents a "diamond structure" with Beijing, Shanghai, Shenzhen-Guangzhou, Chengdu-Chongqing and Wuhan as the apex.

Based on the price difference method, the scale of residential natural gas subsidies in China from 2009 to 2019 was estimated. The Dagum Gini coefficient and LMDI decomposition method were used to explore the spatial differences of subsidies and their inherent evolutionary mechanism. The results show that: (1) Residential natural gas subsidies showed a two-stage feature of "first increase and then decrease", subsidies peaked in 2012. The proportion of subsidies in the eastern, central and northeast regions showed an increasing trend, while that in the western region decreased. The scale of subsidies in all provinces increased to varying degrees, and the provinces with the highest average subsidies were those with large natural gas production and consumption, and provinces along the west-east gas transmission route and coastal economically developed areas. (2) Residential natural gas subsidies showed a spatial distribution feature of "high in the west and low in the east", and the overall regional gap narrowed, and super-variable density gradually became the main source of subsidy differences. In order of magnitude, the differences between regions are west-northeast, East-West, middle-west, east-northeast, middle-northeast, and East-middle. From the perspective of intra-regional differences, the western region had the largest difference, and the northeast region had the smallest difference, the eastern and central regions of the subsidy difference is increasing, the degree of subsidy imbalance is increasing, and the western and northeast regions of the subsidy tend to be balanced. (3) On the whole, the population effect and consumption effect have positive contributions to residential gas subsidies and their effects have been increasing,. The price effect, technology effect and economic effect showed negative contributions to subsidies. There are significant spatial differences in the influencing factors of residents' natural gas subsidies in eastern, central, western and northeast regions, and they change before and after the natural gas price reform.

With steady advancement of stock renewal and cultural tourism integration policies, recreational space has become key topic of academic attention. Combined with new development requirements such as historic and cultural protection, inheritance, and revitalization, numerous studies have actively explored the regeneration path and evolution rules of urban historic recreational spaces. Under the background of clarifying its connotation and regeneration attributes, this paper selected relevant literatures in WOS and CNKI databases during past 20 years, used CiteSpace software to draw knowledge visualization maps, and carried out literature study in accordance with comprehensive and thematic principles to systematically review the research progress at home and abroad. It is found that: ①Since 2004, relevant researches can be divided into embryonic, fluctuating, and rapidly developing stages based on the number of publications and emerging keywords, and spread to natural and social sciences such as Urban and Rural Planning, Tourism, and Geography. ②Foreign research hotspots focus on urban development, heritage regeneration and social management, while domestic researches focus on design practices and applications such as protection and utilization, historical environment and spatial pattern. ③Main research contents at home and abroad are relatively overlapping, concentrating on the structure of material space form, perception of historic recreational imagery, evaluation of comprehensive value system, and strategy of regeneration planning and design. Based on these, this paper summarizes research inspirations and prospects the future direction of deepening domestic themes from the perspectives of ideal structural models, comprehensive historic recreational imagery, dynamic evaluation processes, interdisciplinary foundations, and localized regeneration paths.

Network attention has become an important driving force for the development of ice-snow tourism in China.With the National Bureau of Statistics of China and the Baidu Index as the main data sources, the spatio-temporal differences and influencing factors of network attention on ice-snow tourism in China are analyzed through three modules of Baidu Index:"Search Index" "Crowd Portrait" and "Demand Mapping". The results show that: (1) In terms of time, China's ice-snow tourism network attention is growing year by year, the PC search index is higher than the mobile search index, and seasonal differences are obvious, with November, December and January being the high search months every year. (2) In terms of space, the structure distribution shows the development pattern of "high in the east, balanced in the middle and low in the west", with Beijing, Heilongjiang, Jilin and Guangdong being the provinces with higher ranking of network attention for ice-snow tourism in China.(3)In terms of influencing factors, ranked as economic development level > ice-snow tourism resources > large ice-snow events > regional network penetration rate > per capita consumption expenditure; the proportion of young people is negatively correlated with ice-snow tourism network concern. Finally, it proposes the deep integration of ice-snow tourism with big data and other recommendations to provide a scientific basis and decision-making reference for the formulation of relevant national policies to promote the high-quality development of ice-snow tourism.

Comments on both community-based and transaction-based platforms include tourism attractions, tourism services, and tourist emotions, but whether these two types will lead to similarities and differences in the overall image and segmented image is a proposition worth exploring. Based on the three-dimensional model of "cognition-emotion-integrity", Lijiang ancient city was used as the case area, Sina Weibo and Ctrip reviews representing community-based and transactional data respectively were used as the research data, combined with Python programming to call Baidu Sentiment Dictionary sentiment analysis method, used LDA to refine image themes, and constructed a co-occurrence relationship network map combining VOSviewer and Gephi to Analyze the similarities and differences between two types of data-driven overall image, cognitive image and emotional image and their influencing factors. The results show that 1) The overall image of destinations based on Sina Weibo's community-based and Ctrip's transaction-based reviews is mainly positive, with similar changes in annual image changes, and the distribution of emotional polarity is basically the same. 2) Although both community-based and transaction-based reviews can reflect cognitive and emotional image themes such as destination services, attractions, and environmental economy, the cognitive image theme score of the former is significantly higher than that of the latter, while the emotional image is the opposite. 3) There is little difference in the contribution rate of cognitive and emotional factors to the overall image of the destination driven by the two kinds of review data, while the effect of the economic price factor of the transaction type review is significantly higher than that of the community type review. The research provides a certain reference basis for using large-scale multi-source heterogeneous data to analyze destination image and tourism marketing work.

In China, a lot of cultivated land is left unused and abandoned. How to control the situation of abandoning land has become the key to ensure food security. By building the "abandonment judgment" model, this paper quantitatively described the types of cultivated land abandonment by calculating the difference between the actual multiple cropping index and the potential multiple cropping index, and use the data of Sichuan in 2006-2018 to describe the spatial and temporal distribution of cultivated land abandonment, and analyzed its influencing factors.The results show that: ① From 2006 to 2013, the degree of cultivated land abandonment in all cities and prefectures showed an expanding trend. After the temporary "singularity effect" in 2014, the degree of cultivated land abandonment continued to increase. ② The perennial wasteland is mainly abandoned in high-altitude areas, while the seasonal wasteland is mainly abandoned in low altitude areas, and there is also perennial wasteland. ③ The cities and prefectures with bad natural conditions are more likely to suffer from perennial cultivated land abandonment, while those with high economic development or urbanization rate are more likely to witness seasonal land abandonment. ④ From the perspective of food security, seasonal abandonment is more threatening than perennial abandonment. Therefore, it is necessary to constantly improve the comprehensive benefits of agricultural production, make grain planting profitable, and solve the key problems of "who will farm", "how to farm", and "what will grow in the field".