Various slow slip events(SSEs)with distinct characteristics have been detected globally,particularly in regions with dense Global Navigation Satellite Systems(GNSS)networks.In the Hikurangi subduction zone of New Zeal...Various slow slip events(SSEs)with distinct characteristics have been detected globally,particularly in regions with dense Global Navigation Satellite Systems(GNSS)networks.In the Hikurangi subduction zone of New Zealand,SSEs frequently occur alongside seismic activity,especially in the Manawatu and Kapiti regions.This study analyzes the 2021-2023 Kapiti-Manawatu long-term SSE using daily displacement data(2019-2023)from 53 GPS stations.The network inversion filter(NIF)method is applied to extract slow slip signals,revealing spatial migration with alternating slip between Kapiti and Manawatu,characterized by distinct phases of acceleration and deceleration.Manawatu exhibits higher slip rates,exceeding 4 cm/month,with greater cumulative slip and surface displacement than Kapiti.A moderate temporal correlation(coefficient 0.59)between seismic activity in the region and slip acceleration in Manawatu suggests that seismic events may contribute to the slip,while no significant correlation is observed in Kapiti.展开更多
The Yellow River Basin of China is a key region that contains myriad interactions between human activities and natural environment.Industrialization and urbanization promote social-economic development,but they also h...The Yellow River Basin of China is a key region that contains myriad interactions between human activities and natural environment.Industrialization and urbanization promote social-economic development,but they also have generated a series of environmental and ecological issues in this basin.Previous researches have evaluated urban resilience at the national,regional,urban agglomeration,city,and prefecture levels,but not at the watershed level.To address this research gap and elevate the Yellow River Basin’s urban resilience level,we constructed an urban resilience evaluation index system from five dimensions:industrial resilience,social resilience,environmental resilience,technological resilience,and organizational resilience.The entropy weight method was used to comprehensively evaluate urban resilience in the Yellow River Basin.The exploratory spatial data analysis method was employed to study the spatiotemporal differences in urban resilience in the Yellow River Basin in 2010,2015,and 2020.Furthermore,the grey correlation analysis method was utilized to explore the influencing factors of these differences.The results of this study are as follows:(1)the overall level of urban resilience in the Yellow River Basin was relatively low but showed an increasing trend during 2010–2015,and significant spatial distribution differences were observed,with a higher resilience level in the eastern region and a low-medium resilience level in the western region;(2)the differences in urban resilience were noticeable,with industrial resilience and social resilience being relatively highly developed,whereas organizational resilience and environmental resilience were relatively weak;and(3)the correlation ranking of resilience influencing factors was as follows:science and technology level>administrative power>openness>market forces.This research can provide a basis for improving the resilience level of cities in the Yellow River Basin and contribute to the high-quality development of the region.展开更多
The rural settlement is one of important aspects to understand regional human-environment relationships. Zhangjiakou city, located in the poverty belt around Beijing and Tianjin, was used as an example to analyze the ...The rural settlement is one of important aspects to understand regional human-environment relationships. Zhangjiakou city, located in the poverty belt around Beijing and Tianjin, was used as an example to analyze the evolution of rural settlements during 1985–2010 through the use of statistical and spatial analysis methods. The results demonstrate the following:(1) the area of rural settlements expanded from 665.76 to 928.14 km2 during 1985–2010. Rural settlements in prefecture city of Zhangjiakou were significantly agglomerated in terms of their spatial distribution, which presented an approximately normal distribution over the entire period. Rural settlements were usually distributed within regions where the terrain niche had an elevation of between 900 and 1500 m, and a slope from 5? to 20?;(2) there were significant regional differences in the density and size distribution of rural settlements in Zhangjiakou. The density of rural settlements in 2010 was higher than that in 1985, while there was a clustered distribution of rural settlements in 2010. There was a significant high value cluster in the size distribution, and a local negative correlation between the size and density distribution of rural settlements in Zhangjiakou;(3) rural economic development, investment in agricultural technology, and infrastructure improvement played important roles in the evolution of rural settlements. There were spatial differences in the relationship between the distribution of rural settlements and socio-economic factors in Zhangjiakou. This study provides practical guidance for the achievement of urban and rural integration development and the promotion of a new form of countryside construction.展开更多
A series of plane-strain physical model experiments are carried out to study the spatiotemporal evolution rule of rocks fracture surrounding gob-side roadway, which is subjected to the pressure induced by the mining p...A series of plane-strain physical model experiments are carried out to study the spatiotemporal evolution rule of rocks fracture surrounding gob-side roadway, which is subjected to the pressure induced by the mining process. The digital photogrammetry technology and large deformation analysis method are applied to measure the deformation and fracture of surrounding rocks. The experimental results indicate that the deformation and fracture of coal pillars are the cause to the instability and failure of the surrounding rocks. The spatiotemporal evolution rule of the rock deformation and fracture surrounding gob-side roadway is obtained. The coal pillar and the roof near coal pillar should be strengthened in support design. The engineering application results also can provide a useful guide that the combined support with wire meshes, beam, anchor bolt and cable is an effective method.展开更多
As the main form of new urbanization in China,urban agglomerations are an important platform to support national economic growth,promote coordinated regional development,and participate in international competition an...As the main form of new urbanization in China,urban agglomerations are an important platform to support national economic growth,promote coordinated regional development,and participate in international competition and cooperation.However,they have become core areas for air pollution.This study used PM_(2.5)data from NASA atmospheric remote sensing image inversion from 2000 to 2015 and spatial analysis including a spatial Durbin model to reveal the spatio-temporal evolution characteristics and main factors controlling PM_(2.5)in China's urban agglomerations.The main conclusions are as follows:(1)From 2000 to 2015,the PM_(2.5)concentrations of China's urban agglomerations showed a growing trend with some volatility.In 2007,there was an inflection point.The number of low-concentration cities decreased,while the number of high-concentration cities increased.(2)The concentrations of PM_(2.5)in urban agglomerations were high in the west and low in the east,with the"Hu Line"as the boundary.The spatial differences were significant and increasing.The concentration of PM_(2.5)grew faster in urban agglomerations in the eastern and northeastern regions.(3)The urban agglomeration of PM_(2.5)had significant spatial concentrations.The hot spots were concentrated to the east of the Hu Line,and the number of hot-spot cities continued to rise.The cold spots were concentrated to the west of the Hu Line,and the number of cold-spot cities continued to decline.(4)There was a significant spatial spillover effect of PM_(2.5)pollution among cities within urban agglomerations.The main factors controlling PM_(2.5)pollution in different urban agglomerations had significant differences.Industrialization and energy consumption had a significant positive impact on PM_(2.5)pollution.Foreign direct investment had a significant negative impact on PM_(2.5)pollution in the southeast coastal and border urban agglomerations.Population density had a significant positive impact on PM_(2.5)pollution in a particular region,but this had the opposite effect in neighboring areas.Urbanization rate had a negative impact on PM_(2.5)pollution in national-level urban agglomerations,but this had the opposite effect in regional and local urban agglomerations.A high degree of industrial structure had a significant negative impact on PM_(2.5)pollution in a region,but this had an opposite effect in neighboring regions.Technical support level had a significant impact on PM_(2.5)pollution,but there were lag effects and rebound effects.展开更多
Ecological security is the foundation and guarantee of sustainable development,and its importance is increasingly widely recognized and valued by the world.The Yangtze River Basin is an important ecological security b...Ecological security is the foundation and guarantee of sustainable development,and its importance is increasingly widely recognized and valued by the world.The Yangtze River Basin is an important ecological security barrier in China and the Wanjiang City Belt(WCB)along the Yangtze River is directly related to the ecological security pattern of the entire basin.Based on the Driver-Pressure-State-Impact-Response(DPSIR)model and a geographical information system(GIS)platform,an ecosystem security evaluation index system was constructed to measure and evaluate the evolution of ecosystem security in the WCB,China.Results showed that:1)From 2000 to 2018,the overall level of ecological security in the study area was in a state of either early warning or medium warning,but the level of ecological security in each prefecture-level city was significantly different.2)From the perspective of the evolution of the ecosystem,the value of its comprehensive evaluation index dropped from 4.255 in 2000 to 3.885 in 2018.From the perspective of subsystems,the value of Pressure comprehensive evaluation index is much higher than that of other subsystems,indicating that during the rapid development of the social economy,the pressure on the natural environment tended to rise,and triggered changes in the State and Response subsystems.3)The coefficient of variation(CV)of the Driver was much higher than other factors influencing the ecological security system.There are large differences in the economic development and ecological evolution of the cities in the WCB.This study has improved the theoretical research on regional ecological security,and has certain practical guiding significance for building a beautiful,green and sustainable China and promoting global ecological security.展开更多
Taking social statistic data as basic data,this paper extended the meaning of urban land uses,highlighted the meaning of urban land uses in modern urbanization,which includes direct,indirect and induced land uses,quan...Taking social statistic data as basic data,this paper extended the meaning of urban land uses,highlighted the meaning of urban land uses in modern urbanization,which includes direct,indirect and induced land uses,quantitatively simulated the indirect and induced land uses by the substitution method of agricultural consumption and urban carbon emission and then,analyzed the spatiotemporal evolution of urban land uses in China during 1952–2005 by spatial analysis tool of Geographic Information System. The results indicate that the area of urban land use in China had been increasing since 1952,showing an inversed pyramid structure,i.e.,the direct<the indirect<the induced. Specifically,Chinese urban land use has changed from concentrated distribution in Northwest China to balanced spatial distribution,and the eastern coastal area is under great pressure. Moreover,the northeastern region has moved into the induced dominant stage,while the western region remains at the indirect dominant stage. Finally,it is proposed that in order to guarantee the future demand of urban land use in China,ensuring the induced land use in the eastern region should be taken as a priority goal of Chinese developing policy.展开更多
Located in the western hinterland,Southwest China is a typical mountainous area covered by plateaus,mountains and hills.Its ruggedness hinders regional internal and external connections,and its poor transportation inf...Located in the western hinterland,Southwest China is a typical mountainous area covered by plateaus,mountains and hills.Its ruggedness hinders regional internal and external connections,and its poor transportation infrastructure has long constrained the socioeconomic development of Southwest China.Based on the GIS transportation database,this paper explored the spatiotemporal evolution and characteristics of the land transportation networks and the accessibility of Southwest China from 1917 to 2017.Regional accessibility in Southwest China has significantly improved,and transportation infrastructure has gradually integrated the transportation circles of the52 central cities.The transportation network has followed an evolutionary process from a"hub-spoke pattern"to a"network pattern",while the construction of a high-speed railway(HSR)has brought about significant spatial polarization.We argue that innovation in transportation technology is one of the most effective factors for promoting a significant change in regional accessibility.In addition,the spatial distribution and evolution of accessibility in Southwest China presents a verticalcharacteristic that distinguishes it from the plains,as the spillover effects of new transportation infrastructure on accessibility improvement are partly offset by the mountainous terrain.Additionally,in Southwest China,there is significant"path dependence"in the evolution of the transportation network,since a large portion of the population is concentrated along transportation corridors in mountainous areas.展开更多
Based on the National Land Use/Cover Database of China(NLUD-C) in the end of the 1980s(the 1980s,hereafter), 1995, 2000, 2005, and 2010, 665 cities were selected to study the size distribution and its changes of urban...Based on the National Land Use/Cover Database of China(NLUD-C) in the end of the 1980s(the 1980s,hereafter), 1995, 2000, 2005, and 2010, 665 cities were selected to study the size distribution and its changes of urban lands in China. In this study, the spatiotemporal evolutions of urban land size distribution as well as the influence of administrative-level on these cities were explored by combining urban spatial positions and administrative-levels. Results indicate that: 1) City size distribution using urban lands was more practical and reasonable than using non-agricultural population. 2) In the 1980s, cities with ascending urban land rank were centralized in Eastern China, specially the Changjiang(Yangtze) River Delta, the Zhujiang(Pearl) River Delta, and Beijing-Tianjin-Hebei region. Cities in Central, Western, and Northeast China mainly indicated descending urban land rank. 3) The transfer of national development focus resulted in cities with ascending urban land rank becoming evenly distributed nationwide; however, this trend was slightly centralized around Chengdu, Chongqing, and Wuhan in different periods. 4) During the 1980s to 2010, the proportion of cities with ascending urban land rank in provincial capitals, municipalities, and special administrative regions(high-level cities, hereafter) was consistently higher than those in prefecture- and county-level cities except for 2005–2010. The ranks of the majority of the prefecture- and county-level cities were mainly descending, supported by ascending; the proportion of cities with unchanged rank is small. This study breaks through the bottleneck of traditional research in the area of city size distribution by examining urban land replacing the non-agricultural population. The current study also provides scientific explanation for the healthy and reasonable development of urban land as well as the coordinated development of population urbanization and land urbanization.展开更多
Cemented paste backfill(CPB)and rock interface interaction causes the formation of an interfacial loading and affects the thermal,hydraulic,mechanical,and chemical processes in bulk CPB and thus its in-situ behavior.I...Cemented paste backfill(CPB)and rock interface interaction causes the formation of an interfacial loading and affects the thermal,hydraulic,mechanical,and chemical processes in bulk CPB and thus its in-situ behavior.In this study,a new meter-sized column model is developed to systematically investigate the multiphysics processes in CPB under interfacial loading.The obtained results discover that for the mechanical process,the interfacial loading leads to a reduced settlement and a weakened stress level in CPB.For the hydraulic process,lower matric suction and smaller moisture content coexist in CPB under interfacial loading.For the thermal process,the interfacial loading weakens the porosity-dependent thermal conduction and causes retardation in temperature variation relative to the ambient temperature.For the chemical process,weakened cement hydration with smaller electrical conductivity was observed in CPB under interfacial loading.Therefore,the obtained results reveal the linkage between the interfacial loading and multiphysics processes in CPB and thus contribute to an in-depth understanding of the multiphysics behavior of CPB in underground mines.展开更多
The influence of the picosecond(ps) pulsed burst with a nanosecond scale of temporal separation(50 ns) on filamentary traces in sapphire substrate is investigated. The spatiotemporal evolution of the filamentary plasm...The influence of the picosecond(ps) pulsed burst with a nanosecond scale of temporal separation(50 ns) on filamentary traces in sapphire substrate is investigated. The spatiotemporal evolution of the filamentary plasma string induced by sub-pulses of the burst-mode is revealed according to the analysis of the instantaneous photoluminescence images. Due to the presence of residual plasma, the energy loss of sub-pulse during the balancing of self-focusing effect is reduced, and thus refreshes the plasma via refocusing. The refreshed plasma peak generated by the subsequent subpulse appears at relatively low density positions in the formed filamentary plasma string, which results in more uniform densities and less spatial overlap among the plasma peaks. The continuity and uniformity of the filamentary trace in sapphire are enhanced by the burst-mode. Besides, the burst filamentary propagation can also remain effective when the sub-pulse energy is below the self-focusing threshold. Based on this uniform and precise energy propagation mode, the feasibility of its use for the laser lift-off(LLO) process is verified.展开更多
Based on the seismic phase reports of the Yangbi area from January 1 to June 25,2021,and the waveform data of M≥4 earthquakes,we obtained the relocation results and focal mechanism solutions of the M_(S)6.4 Yangbi ea...Based on the seismic phase reports of the Yangbi area from January 1 to June 25,2021,and the waveform data of M≥4 earthquakes,we obtained the relocation results and focal mechanism solutions of the M_(S)6.4 Yangbi earthquake sequence using the HypoDD and CAP methods.Based on our results,our main conclusions are as follows:(1)the M_(S)6.4 Yangbi earthquake sequence is a typical foreshock-mainshock-aftershock sequence.The fore-shocks of the first two stages have the obvious fronts of migration and their migration rate increased gradually.There was no apparent front of migration during the third stage,and the occurrence of the mainshock was related to stress triggering from a M5.3 foreshock.We tentatively speculate that the rupture pattern of the Yangbi earthquake sequence conforms to the cascading-rupture model;and(2)the main fault of the M_(S)6.4 Yangbi earthquake sequence is a NW-trending right-lateral strike-slip fault.As time progressed,a minor conjugate aftershock belt formed at the northwest end of this fault,and a dendritic branching structure emerged in the southern fault segment,showing a complex seismogenic fault structure.We suggested that the fault of the Yangbi earthquake sequence may be a young sub-fault of the Weixi-Weishan fault.展开更多
Investigating urban expansion patterns aids in the management of urbanization and in ameliorating the socioeconomic and environmental issues associated with economic transformation and sustainable development.Applying...Investigating urban expansion patterns aids in the management of urbanization and in ameliorating the socioeconomic and environmental issues associated with economic transformation and sustainable development.Applying Harmonized Defense Meteorological Satellite Program-Operational Line-scan System(DMSP-OLS)and the Suomi National Polar-Orbiting Partnership-Visible Infrared Imagery Radiometer Suite(NPP-VIIRS)Nighttime Light(NTL)data,this paper investigated the characteristics of urban landscape in West Africa.Using the harmonized NTL data,spatial comparison and empirical threshold methods were employed to detect urban changes from 1993 to 2018.We examined the rate of urban change and calculated the direction of the urban expansion of West Africa using the center-of-gravity method for urban areas.In addition,we used the landscape expansion index method to assess the processes and stages of urban growth in West Africa.The accuracy of urban area extraction based on NTL data were R^(2)=0.8314 in 2000,R^(2)=0.8809 in 2006,R^(2)=0.9051 in 2012 for the DMSP-OLS and the simulated NPP-VIIRS was R^(2)=0.8426 in 2018,by using Google Earth images as validation.The results indicated that there was a high rate and acceleration of urban landscapes in West Africa,with rates of 0.0160,0.0173,0.0189,and 0.0686,and accelerations of 0.31,0.42,0.54,and 0.90 for the periods of 1998–2003,2003–2008,2008–2013,and 2013–2018,respectively.The expansion direction of urban agglomeration in West Africa during 1993–2018 was mainly from the coast to inland.However,cities located in the Sahel Region of Africa and in the middle zone expanded from north to south.Finally,the results showed that the urban landscape of West Africa was mainly in a scattered and disordered’diffusion’process,whereas only a few cities located in coastal areas experiencing the process of’coalescence’according to urban growth phase theory.This study provides urban planners with relevant insights for the urban expansion characteristics of West Africa.展开更多
Since China’s reform and opening up in 1978,the acceleration of industrialization and urbanization in China had led to dramatic changes in the pattern of urban-rural land use.In this paper,we focused on the rural ind...Since China’s reform and opening up in 1978,the acceleration of industrialization and urbanization in China had led to dramatic changes in the pattern of urban-rural land use.In this paper,we focused on the rural industrialized areas in central China(Xinxiang County and Changyuan City of Henan Province).We used the average nearest neighbor index,spatial statistical analysis,and a structural equation model to analyze the spatiotemporal evolution and influencing factors of urban-rural construction land based on multisource spatial data and survey data.The results showed that:1)from 1975 to 2019,the spatial distribution of urban-rural construction land in rural industrialized areas had evolved from homogeneous distribution to local agglomeration.In terms of comparative analysis of cases,the spatial distribution of urban-rural construction land in Changyuan City had shown a trend from diffusion to agglomeration,and Xinxiang County had overall shown a spatial change from homogenization to agglomeration and then to regional integration development.2)The hot spots with increased urban-rural construction land significantly expanded,and they had a high degree of spatial overlap with industrial development.Among them,Xinxiang County was concentrated in central and marginal areas,and Changyuan was mainly concentrated in central urban areas.3)From the evolution of spatial proximity of urban-rural construction land,rural industrialized areas generally decline,showing the characteristics of internal differentiation in the rate of change.4)Industrial development,social economy,the policy environment,and urban development played a positive role in promoting the expansion of urban-rural construction land in rural industrialized areas.To promote the optimal use of regional land and the integrated development of urban-rural areas,we should combine the advantages of regional endowment,formulate development strategies according to local conditions,and adjust the way that land is used in a timely manner.展开更多
Since joining the WTO, China’s automobile market has shown a rapid development trend, and the automobile market is becoming more and more important to China’s economic recovery and high-quality development. The auto...Since joining the WTO, China’s automobile market has shown a rapid development trend, and the automobile market is becoming more and more important to China’s economic recovery and high-quality development. The automobile manufacturing industry is one of the pillar industries of China, but facing downward pressure since 2018. The paper studies spatiotemporal evolution characteristics and influencing factors of automobile market since WTO Accession using methods including ESDA, DTW cluster analysis and Spatial panel Dubin model. The result shows that: 1) China’s automobile sales have grown rapidly and three development stages have occurred since WTO Accession;2) Four types of China’s automobile markets have significant spatial differentiation, while the same pattern present spatial agglomeration characteristics;3) The crucial reasons for spatial separation of production and sales in China’s automobile market include implementation of purchase restrictions in more and more cities, gradual consolidation of spatial pattern of automobile production, and the fact that some automobile production areas are far away from consumer market;4) The provincial spatial weighted average centers of automobile sales are mainly distributed in southeast Henan, and show a trend of moving to the southwest;5) The estimated coefficients of factors such as GDP, financial added value, the proportion of highway, the volume of highway freight, and implementation of automobile consumption incentive policies are all significantly positive, and some factors have positive spatial spillover effects. Existing research on the automobile market lacks analysis based on long-time series data. This study uses long-time series data to provide a certain reference for future research in related directions.展开更多
Introduction:Depression among older adults has emerged as a critical public health concern in China.While previous studies have demonstrated spatial heterogeneity in the prevalence of depressive symptoms among elderly...Introduction:Depression among older adults has emerged as a critical public health concern in China.While previous studies have demonstrated spatial heterogeneity in the prevalence of depressive symptoms among elderly populations across China,the spatiotemporal evolution of this phenomenon remains inadequately explored.This study aimed to estimate city-level prevalence of depressive symptoms among elderly Chinese residents from 2013 to 2020 and analyze its spatial-temporal patterns.Methods:Data were obtained from the China Health and Retirement Longitudinal Study(CHARLS)surveys conducted in 2013,2015,2018,and 2020.The study employed sandwich estimation methodology to calculate prevalence rates,while global autocorrelation analysis was utilized to evaluate spatial patterns in the distribution of depressive symptoms.Results:The average prevalence of depressive symptoms among Chinese older adults demonstrated a consistent increase from 30.27%[95%confidence interval(CI):24.53%,36.02%]in 2013 to 37.79%(95%CI:31.01%,44.56%)in 2020.Higher prevalence rates were observed in cities across Southwest,Northwest,and Central China,although no significant spatial aggregation was detected.Conclusions:The prevalence of depressive symptoms among older adults in China showed a substantial increase between 2013 and 2020.Enhanced preventive measures and interventions are particularly needed to improve mental well-being among elderly populations in China’s western and central regions.展开更多
Given the significance of cities as key execution units in carbon reduction initiatives,their role is crucial for the building sector and for China to achieve its“carbon peak and carbon neutrality”goals.Based on his...Given the significance of cities as key execution units in carbon reduction initiatives,their role is crucial for the building sector and for China to achieve its“carbon peak and carbon neutrality”goals.Based on historical data on carbon emissions in the municipal-level building sector,this study employs spatiotemporal analysis models—such as Moran’s Index,kernel density estimation,and center of gravity migration analysis—to capture the spatial heterogeneity and dynamic evolution of carbon emissions from 2015 to 2020.By integrating an extended Kaya identity with the k-means clustering algorithm and embedding a machine learning algorithm with optimal test performance,the study identifies the heterogeneity in development types and influencing factors among different cities.The results indicate that carbon emissions in the municipal-level building sector across Chinese cities increasingly concentrate on higher emission ranges.North China serves as the high-value center for carbon emissions,whereas Southwest China is the low-value center.Analysis of center of gravity migration trajectories reveals that factors such as energy consumption per unit of GDP significantly drive the growth of carbon emissions in the building sector,while the general public budget expenditure intensity exerts an inhibitory effect.Additionally,Chinese cities are classified into five distinct development types.Compared to traditional nonlinear models and other machine learning models,XGBoost achieves the best predictive performance for carbon emissions across of buildings different city types,with R^(2)values of 0.998,0.992,0.983,0.995,and 0.986.These findings underscore the need to develop differentiated carbon reduction strategies that align with the unique development characteristics and influencing factors of each city type.展开更多
With the rapid development of urbanization and industrialization in China,the expansion of construction land and irrational utilization of cultivated land have led to issues such as cultivated land marginalization,ext...With the rapid development of urbanization and industrialization in China,the expansion of construction land and irrational utilization of cultivated land have led to issues such as cultivated land marginalization,extensive use,non-grain conversion,and non-agriculturalization.These issues are a major threat to sustainable agricultural development,but existing research suffers from limitations including failure to assess the multifunctionality of cultivated land(MCL)from the perspective of sustainable agricultural development.This study constructed an agricultural production function(APF)-social security function(SSF)-ecological maintenance function(EMF)-landscape aesthetic function(LAF)classification system.Using this comprehensive evaluation model,the MCL values for typical provinces in southwestern mountainous areas of China(Guizhou,Sichuan,and Yunnan)were calculated in detail,and their spatiotemporal evolutionary characteristics were explored.Concurrently,the Spearman rank correlation coefficient,geographically weighted regression(GWR)and redundancy model were used to deeply explore the relationships among cultivated land functions and their influencing factors.The results showed three important points.(1)Over the past two decades,the comprehensive values and four sub-functional values of cultivated land in southwestern mountainous areas have shown increasing trends in the order of SSF>EMF>LAF>APF.The values and rates of change of each sub-functional value show obvious spatial variation.However,the spatial gap in cultivated land functions has adverse effects on sustainable agricultural development.(2)There are clear correlations between each pair of the four major functions of cultivated land during the study period,and the number of results reaching significance among the six correlations between the four main cultivated land functions increased significantly from 2000 to 2020.Simultaneously,there are noticeable spatiotemporal differences in the trade-offs and synergies among the MCLs.(3)The development of MCL is most significantly influenced by socioeconomic factors such as the per capita net income of rural residents.Therefore,formulating reasonable land protection policies is imperative for promoting the sustainable development of agriculture.The results of this study can provide guidance for the rational layout and coordinated development of MCL space,for promoting sustainable agricultural development and ensuring food security.展开更多
Based on data from Beijing museums spanning 1980 to 2020,this study employs spatial analysis methods such as geographical concentration index,imbalance index,kernel density and standard deviation ellipse characterize ...Based on data from Beijing museums spanning 1980 to 2020,this study employs spatial analysis methods such as geographical concentration index,imbalance index,kernel density and standard deviation ellipse characterize the temporal and spatial evolution of Beijing museums and analyze their influencing factors.The re-search shows that the museum development in Beijing has undergone three stages:a slow start,high-speed de-velopment and high-quality upgrading.The development of cultural relics and industrial museums tends towards balance,and the market-oriented development of museums continues to improve.The“single core”concentration distribution of Beijing museums is prominent,showing a typical“center edge”distribution with a trend of new core formation during expansion.Temporally,Beijing museums exhibit an inverted“L”evolution pattern,trending from north to east with Haidian and Chaoyang districts poised to become new centers.Distribution across intervals is uneven,yet the overall pattern is evolving towards a balanced distribution.The research on factors influencing the spatial distribution of museums,including population,resources,economy,and transportation,innovatively intro-duces educational factors.It shows that Beijing museums are transforming from“population driven”and“resource driven”to“education driven”over time.展开更多
The shear behavior of intact loess is intricately linked to the spatiotemporal evolution of its mesoscopic characteristics.Understanding this relationship is crucial for comprehending and preventing loess landslides.T...The shear behavior of intact loess is intricately linked to the spatiotemporal evolution of its mesoscopic characteristics.Understanding this relationship is crucial for comprehending and preventing loess landslides.To systematically investigate this connection,our study conducted triaxial shear tests on both Malan loess and Lishi loess,encompassing variations in confining pressures.Additionally,nondestructive,real-time CT observations were employed to track the dynamic evolution of loess mesostructures.The experimental findings illuminate significant insights.The Malan loess exhibits strain hardening during shearing,with the degree of hardening exhibiting an increase in tandem with rising confining pressure.Conversely,the Lishi loess manifests a transition from strain softening to strain hardening as confining pressure increases.Under elevated confining pressure,the specimen undergoes structural damage while concurrently forming a denser configuration through particle friction and rearrangement,leading to strain hardening and volume reduction.In contrast,the central portion of the specimen exhibits heightened sensitivity to deformation under low confining pressures.Gradual crack expansion,emanating from the center and progressing towards the ends,results in progressive specimen destruction and a concomitant reduction in stress.On a macroscopic level,the specimen undergoes expansion at its center while contracting at its ends.The findings of this study unveil the intricate mechanisms governing loess deformation in the presence of varying confining pressures,thereby contributing significantly to our understanding of loess landslide formation and providing a robust theoretical framework for preventive measures.展开更多
基金funded by the National Natural Science Foundation of China(41704031,42374040)the Natural Science Foundation of Jiangxi Science and Technology Department(20232BAB203073)the Key Laboratory of Mine Environmental Monitoring and Improving around Poyang Lake,Ministry of Natural Resources(MEMI-2021-2022-29).
文摘Various slow slip events(SSEs)with distinct characteristics have been detected globally,particularly in regions with dense Global Navigation Satellite Systems(GNSS)networks.In the Hikurangi subduction zone of New Zealand,SSEs frequently occur alongside seismic activity,especially in the Manawatu and Kapiti regions.This study analyzes the 2021-2023 Kapiti-Manawatu long-term SSE using daily displacement data(2019-2023)from 53 GPS stations.The network inversion filter(NIF)method is applied to extract slow slip signals,revealing spatial migration with alternating slip between Kapiti and Manawatu,characterized by distinct phases of acceleration and deceleration.Manawatu exhibits higher slip rates,exceeding 4 cm/month,with greater cumulative slip and surface displacement than Kapiti.A moderate temporal correlation(coefficient 0.59)between seismic activity in the region and slip acceleration in Manawatu suggests that seismic events may contribute to the slip,while no significant correlation is observed in Kapiti.
基金supported by the Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences.
文摘The Yellow River Basin of China is a key region that contains myriad interactions between human activities and natural environment.Industrialization and urbanization promote social-economic development,but they also have generated a series of environmental and ecological issues in this basin.Previous researches have evaluated urban resilience at the national,regional,urban agglomeration,city,and prefecture levels,but not at the watershed level.To address this research gap and elevate the Yellow River Basin’s urban resilience level,we constructed an urban resilience evaluation index system from five dimensions:industrial resilience,social resilience,environmental resilience,technological resilience,and organizational resilience.The entropy weight method was used to comprehensively evaluate urban resilience in the Yellow River Basin.The exploratory spatial data analysis method was employed to study the spatiotemporal differences in urban resilience in the Yellow River Basin in 2010,2015,and 2020.Furthermore,the grey correlation analysis method was utilized to explore the influencing factors of these differences.The results of this study are as follows:(1)the overall level of urban resilience in the Yellow River Basin was relatively low but showed an increasing trend during 2010–2015,and significant spatial distribution differences were observed,with a higher resilience level in the eastern region and a low-medium resilience level in the western region;(2)the differences in urban resilience were noticeable,with industrial resilience and social resilience being relatively highly developed,whereas organizational resilience and environmental resilience were relatively weak;and(3)the correlation ranking of resilience influencing factors was as follows:science and technology level>administrative power>openness>market forces.This research can provide a basis for improving the resilience level of cities in the Yellow River Basin and contribute to the high-quality development of the region.
基金financially supported by the National Natural Science Foundation of China (Grant No. 41571087)
文摘The rural settlement is one of important aspects to understand regional human-environment relationships. Zhangjiakou city, located in the poverty belt around Beijing and Tianjin, was used as an example to analyze the evolution of rural settlements during 1985–2010 through the use of statistical and spatial analysis methods. The results demonstrate the following:(1) the area of rural settlements expanded from 665.76 to 928.14 km2 during 1985–2010. Rural settlements in prefecture city of Zhangjiakou were significantly agglomerated in terms of their spatial distribution, which presented an approximately normal distribution over the entire period. Rural settlements were usually distributed within regions where the terrain niche had an elevation of between 900 and 1500 m, and a slope from 5? to 20?;(2) there were significant regional differences in the density and size distribution of rural settlements in Zhangjiakou. The density of rural settlements in 2010 was higher than that in 1985, while there was a clustered distribution of rural settlements in 2010. There was a significant high value cluster in the size distribution, and a local negative correlation between the size and density distribution of rural settlements in Zhangjiakou;(3) rural economic development, investment in agricultural technology, and infrastructure improvement played important roles in the evolution of rural settlements. There were spatial differences in the relationship between the distribution of rural settlements and socio-economic factors in Zhangjiakou. This study provides practical guidance for the achievement of urban and rural integration development and the promotion of a new form of countryside construction.
基金supported by the National Natural Science Foundation of China (No. 51174197)the Major State Basic Research Development Program of China (No. 2014CB046905)+1 种基金State Key Laboratory for Geo Mechanics and Deep Underground Engineering (CUMT) (No. SKLGDUEK1503)the ‘Qing Lan’ Project of Jiangsu Province
文摘A series of plane-strain physical model experiments are carried out to study the spatiotemporal evolution rule of rocks fracture surrounding gob-side roadway, which is subjected to the pressure induced by the mining process. The digital photogrammetry technology and large deformation analysis method are applied to measure the deformation and fracture of surrounding rocks. The experimental results indicate that the deformation and fracture of coal pillars are the cause to the instability and failure of the surrounding rocks. The spatiotemporal evolution rule of the rock deformation and fracture surrounding gob-side roadway is obtained. The coal pillar and the roof near coal pillar should be strengthened in support design. The engineering application results also can provide a useful guide that the combined support with wire meshes, beam, anchor bolt and cable is an effective method.
基金National Natural Science Foundation of China,No.41771181National Key Research and Development Plan,No.2017YFC0505702Open Fund Project of New Urbanization Research Institute of Tsinghua University,No.TUCSU-K-17015-01。
文摘As the main form of new urbanization in China,urban agglomerations are an important platform to support national economic growth,promote coordinated regional development,and participate in international competition and cooperation.However,they have become core areas for air pollution.This study used PM_(2.5)data from NASA atmospheric remote sensing image inversion from 2000 to 2015 and spatial analysis including a spatial Durbin model to reveal the spatio-temporal evolution characteristics and main factors controlling PM_(2.5)in China's urban agglomerations.The main conclusions are as follows:(1)From 2000 to 2015,the PM_(2.5)concentrations of China's urban agglomerations showed a growing trend with some volatility.In 2007,there was an inflection point.The number of low-concentration cities decreased,while the number of high-concentration cities increased.(2)The concentrations of PM_(2.5)in urban agglomerations were high in the west and low in the east,with the"Hu Line"as the boundary.The spatial differences were significant and increasing.The concentration of PM_(2.5)grew faster in urban agglomerations in the eastern and northeastern regions.(3)The urban agglomeration of PM_(2.5)had significant spatial concentrations.The hot spots were concentrated to the east of the Hu Line,and the number of hot-spot cities continued to rise.The cold spots were concentrated to the west of the Hu Line,and the number of cold-spot cities continued to decline.(4)There was a significant spatial spillover effect of PM_(2.5)pollution among cities within urban agglomerations.The main factors controlling PM_(2.5)pollution in different urban agglomerations had significant differences.Industrialization and energy consumption had a significant positive impact on PM_(2.5)pollution.Foreign direct investment had a significant negative impact on PM_(2.5)pollution in the southeast coastal and border urban agglomerations.Population density had a significant positive impact on PM_(2.5)pollution in a particular region,but this had the opposite effect in neighboring areas.Urbanization rate had a negative impact on PM_(2.5)pollution in national-level urban agglomerations,but this had the opposite effect in regional and local urban agglomerations.A high degree of industrial structure had a significant negative impact on PM_(2.5)pollution in a region,but this had an opposite effect in neighboring regions.Technical support level had a significant impact on PM_(2.5)pollution,but there were lag effects and rebound effects.
基金Under the auspices of National Natural Science Foundation of China(No.41571124)。
文摘Ecological security is the foundation and guarantee of sustainable development,and its importance is increasingly widely recognized and valued by the world.The Yangtze River Basin is an important ecological security barrier in China and the Wanjiang City Belt(WCB)along the Yangtze River is directly related to the ecological security pattern of the entire basin.Based on the Driver-Pressure-State-Impact-Response(DPSIR)model and a geographical information system(GIS)platform,an ecosystem security evaluation index system was constructed to measure and evaluate the evolution of ecosystem security in the WCB,China.Results showed that:1)From 2000 to 2018,the overall level of ecological security in the study area was in a state of either early warning or medium warning,but the level of ecological security in each prefecture-level city was significantly different.2)From the perspective of the evolution of the ecosystem,the value of its comprehensive evaluation index dropped from 4.255 in 2000 to 3.885 in 2018.From the perspective of subsystems,the value of Pressure comprehensive evaluation index is much higher than that of other subsystems,indicating that during the rapid development of the social economy,the pressure on the natural environment tended to rise,and triggered changes in the State and Response subsystems.3)The coefficient of variation(CV)of the Driver was much higher than other factors influencing the ecological security system.There are large differences in the economic development and ecological evolution of the cities in the WCB.This study has improved the theoretical research on regional ecological security,and has certain practical guiding significance for building a beautiful,green and sustainable China and promoting global ecological security.
基金Under the auspices of Key Program of National Natural Science Foundation of China (No. 40535026)
文摘Taking social statistic data as basic data,this paper extended the meaning of urban land uses,highlighted the meaning of urban land uses in modern urbanization,which includes direct,indirect and induced land uses,quantitatively simulated the indirect and induced land uses by the substitution method of agricultural consumption and urban carbon emission and then,analyzed the spatiotemporal evolution of urban land uses in China during 1952–2005 by spatial analysis tool of Geographic Information System. The results indicate that the area of urban land use in China had been increasing since 1952,showing an inversed pyramid structure,i.e.,the direct<the indirect<the induced. Specifically,Chinese urban land use has changed from concentrated distribution in Northwest China to balanced spatial distribution,and the eastern coastal area is under great pressure. Moreover,the northeastern region has moved into the induced dominant stage,while the western region remains at the indirect dominant stage. Finally,it is proposed that in order to guarantee the future demand of urban land use in China,ensuring the induced land use in the eastern region should be taken as a priority goal of Chinese developing policy.
基金supported by the National Natural Science Foundation of China(Grants No.41671159)Fundamental Research Funds for the Central Universities for funding(Grants No.XDJK2018B011)Major Projects on Philosophy and Social Sciences of Chongqing Education Commission(Grants No.19SKZDZX08)。
文摘Located in the western hinterland,Southwest China is a typical mountainous area covered by plateaus,mountains and hills.Its ruggedness hinders regional internal and external connections,and its poor transportation infrastructure has long constrained the socioeconomic development of Southwest China.Based on the GIS transportation database,this paper explored the spatiotemporal evolution and characteristics of the land transportation networks and the accessibility of Southwest China from 1917 to 2017.Regional accessibility in Southwest China has significantly improved,and transportation infrastructure has gradually integrated the transportation circles of the52 central cities.The transportation network has followed an evolutionary process from a"hub-spoke pattern"to a"network pattern",while the construction of a high-speed railway(HSR)has brought about significant spatial polarization.We argue that innovation in transportation technology is one of the most effective factors for promoting a significant change in regional accessibility.In addition,the spatial distribution and evolution of accessibility in Southwest China presents a verticalcharacteristic that distinguishes it from the plains,as the spillover effects of new transportation infrastructure on accessibility improvement are partly offset by the mountainous terrain.Additionally,in Southwest China,there is significant"path dependence"in the evolution of the transportation network,since a large portion of the population is concentrated along transportation corridors in mountainous areas.
基金the Young Scientist Fund of National Nature Science Foundation of China(No.41101148)
文摘Based on the National Land Use/Cover Database of China(NLUD-C) in the end of the 1980s(the 1980s,hereafter), 1995, 2000, 2005, and 2010, 665 cities were selected to study the size distribution and its changes of urban lands in China. In this study, the spatiotemporal evolutions of urban land size distribution as well as the influence of administrative-level on these cities were explored by combining urban spatial positions and administrative-levels. Results indicate that: 1) City size distribution using urban lands was more practical and reasonable than using non-agricultural population. 2) In the 1980s, cities with ascending urban land rank were centralized in Eastern China, specially the Changjiang(Yangtze) River Delta, the Zhujiang(Pearl) River Delta, and Beijing-Tianjin-Hebei region. Cities in Central, Western, and Northeast China mainly indicated descending urban land rank. 3) The transfer of national development focus resulted in cities with ascending urban land rank becoming evenly distributed nationwide; however, this trend was slightly centralized around Chengdu, Chongqing, and Wuhan in different periods. 4) During the 1980s to 2010, the proportion of cities with ascending urban land rank in provincial capitals, municipalities, and special administrative regions(high-level cities, hereafter) was consistently higher than those in prefecture- and county-level cities except for 2005–2010. The ranks of the majority of the prefecture- and county-level cities were mainly descending, supported by ascending; the proportion of cities with unchanged rank is small. This study breaks through the bottleneck of traditional research in the area of city size distribution by examining urban land replacing the non-agricultural population. The current study also provides scientific explanation for the healthy and reasonable development of urban land as well as the coordinated development of population urbanization and land urbanization.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC).
文摘Cemented paste backfill(CPB)and rock interface interaction causes the formation of an interfacial loading and affects the thermal,hydraulic,mechanical,and chemical processes in bulk CPB and thus its in-situ behavior.In this study,a new meter-sized column model is developed to systematically investigate the multiphysics processes in CPB under interfacial loading.The obtained results discover that for the mechanical process,the interfacial loading leads to a reduced settlement and a weakened stress level in CPB.For the hydraulic process,lower matric suction and smaller moisture content coexist in CPB under interfacial loading.For the thermal process,the interfacial loading weakens the porosity-dependent thermal conduction and causes retardation in temperature variation relative to the ambient temperature.For the chemical process,weakened cement hydration with smaller electrical conductivity was observed in CPB under interfacial loading.Therefore,the obtained results reveal the linkage between the interfacial loading and multiphysics processes in CPB and thus contribute to an in-depth understanding of the multiphysics behavior of CPB in underground mines.
基金Project(51975017) supported by the National Natural Science Foundation of ChinaProject(KZ202110005012) supported by the Scientific Research Project of Beijing Educational Committee+1 种基金ChinaProject(2018YFB1107500) supported by the National Key R&D Program of China。
文摘The influence of the picosecond(ps) pulsed burst with a nanosecond scale of temporal separation(50 ns) on filamentary traces in sapphire substrate is investigated. The spatiotemporal evolution of the filamentary plasma string induced by sub-pulses of the burst-mode is revealed according to the analysis of the instantaneous photoluminescence images. Due to the presence of residual plasma, the energy loss of sub-pulse during the balancing of self-focusing effect is reduced, and thus refreshes the plasma via refocusing. The refreshed plasma peak generated by the subsequent subpulse appears at relatively low density positions in the formed filamentary plasma string, which results in more uniform densities and less spatial overlap among the plasma peaks. The continuity and uniformity of the filamentary trace in sapphire are enhanced by the burst-mode. Besides, the burst filamentary propagation can also remain effective when the sub-pulse energy is below the self-focusing threshold. Based on this uniform and precise energy propagation mode, the feasibility of its use for the laser lift-off(LLO) process is verified.
文摘Based on the seismic phase reports of the Yangbi area from January 1 to June 25,2021,and the waveform data of M≥4 earthquakes,we obtained the relocation results and focal mechanism solutions of the M_(S)6.4 Yangbi earthquake sequence using the HypoDD and CAP methods.Based on our results,our main conclusions are as follows:(1)the M_(S)6.4 Yangbi earthquake sequence is a typical foreshock-mainshock-aftershock sequence.The fore-shocks of the first two stages have the obvious fronts of migration and their migration rate increased gradually.There was no apparent front of migration during the third stage,and the occurrence of the mainshock was related to stress triggering from a M5.3 foreshock.We tentatively speculate that the rupture pattern of the Yangbi earthquake sequence conforms to the cascading-rupture model;and(2)the main fault of the M_(S)6.4 Yangbi earthquake sequence is a NW-trending right-lateral strike-slip fault.As time progressed,a minor conjugate aftershock belt formed at the northwest end of this fault,and a dendritic branching structure emerged in the southern fault segment,showing a complex seismogenic fault structure.We suggested that the fault of the Yangbi earthquake sequence may be a young sub-fault of the Weixi-Weishan fault.
基金Under the auspices of National Natural Science Foundation of China(No.41971202)。
文摘Investigating urban expansion patterns aids in the management of urbanization and in ameliorating the socioeconomic and environmental issues associated with economic transformation and sustainable development.Applying Harmonized Defense Meteorological Satellite Program-Operational Line-scan System(DMSP-OLS)and the Suomi National Polar-Orbiting Partnership-Visible Infrared Imagery Radiometer Suite(NPP-VIIRS)Nighttime Light(NTL)data,this paper investigated the characteristics of urban landscape in West Africa.Using the harmonized NTL data,spatial comparison and empirical threshold methods were employed to detect urban changes from 1993 to 2018.We examined the rate of urban change and calculated the direction of the urban expansion of West Africa using the center-of-gravity method for urban areas.In addition,we used the landscape expansion index method to assess the processes and stages of urban growth in West Africa.The accuracy of urban area extraction based on NTL data were R^(2)=0.8314 in 2000,R^(2)=0.8809 in 2006,R^(2)=0.9051 in 2012 for the DMSP-OLS and the simulated NPP-VIIRS was R^(2)=0.8426 in 2018,by using Google Earth images as validation.The results indicated that there was a high rate and acceleration of urban landscapes in West Africa,with rates of 0.0160,0.0173,0.0189,and 0.0686,and accelerations of 0.31,0.42,0.54,and 0.90 for the periods of 1998–2003,2003–2008,2008–2013,and 2013–2018,respectively.The expansion direction of urban agglomeration in West Africa during 1993–2018 was mainly from the coast to inland.However,cities located in the Sahel Region of Africa and in the middle zone expanded from north to south.Finally,the results showed that the urban landscape of West Africa was mainly in a scattered and disordered’diffusion’process,whereas only a few cities located in coastal areas experiencing the process of’coalescence’according to urban growth phase theory.This study provides urban planners with relevant insights for the urban expansion characteristics of West Africa.
基金Under the auspices of National Natural Science Foundation of China(No.42271225)Research Program Fund for Humanities and Social Sciences of the Ministry of Education of China(No.22YJA790050)+2 种基金Henan Provincial Planning Fund for Philosophy and Social Sciences(No.2022BJJ011)Postgraduate Cultivating Innovation Action Plan of Henan University(No.SYLYC2022014)Henan University of Economics and Law Huang Tingfang/Xinhe Young Scholars Program(No.13)。
文摘Since China’s reform and opening up in 1978,the acceleration of industrialization and urbanization in China had led to dramatic changes in the pattern of urban-rural land use.In this paper,we focused on the rural industrialized areas in central China(Xinxiang County and Changyuan City of Henan Province).We used the average nearest neighbor index,spatial statistical analysis,and a structural equation model to analyze the spatiotemporal evolution and influencing factors of urban-rural construction land based on multisource spatial data and survey data.The results showed that:1)from 1975 to 2019,the spatial distribution of urban-rural construction land in rural industrialized areas had evolved from homogeneous distribution to local agglomeration.In terms of comparative analysis of cases,the spatial distribution of urban-rural construction land in Changyuan City had shown a trend from diffusion to agglomeration,and Xinxiang County had overall shown a spatial change from homogenization to agglomeration and then to regional integration development.2)The hot spots with increased urban-rural construction land significantly expanded,and they had a high degree of spatial overlap with industrial development.Among them,Xinxiang County was concentrated in central and marginal areas,and Changyuan was mainly concentrated in central urban areas.3)From the evolution of spatial proximity of urban-rural construction land,rural industrialized areas generally decline,showing the characteristics of internal differentiation in the rate of change.4)Industrial development,social economy,the policy environment,and urban development played a positive role in promoting the expansion of urban-rural construction land in rural industrialized areas.To promote the optimal use of regional land and the integrated development of urban-rural areas,we should combine the advantages of regional endowment,formulate development strategies according to local conditions,and adjust the way that land is used in a timely manner.
文摘Since joining the WTO, China’s automobile market has shown a rapid development trend, and the automobile market is becoming more and more important to China’s economic recovery and high-quality development. The automobile manufacturing industry is one of the pillar industries of China, but facing downward pressure since 2018. The paper studies spatiotemporal evolution characteristics and influencing factors of automobile market since WTO Accession using methods including ESDA, DTW cluster analysis and Spatial panel Dubin model. The result shows that: 1) China’s automobile sales have grown rapidly and three development stages have occurred since WTO Accession;2) Four types of China’s automobile markets have significant spatial differentiation, while the same pattern present spatial agglomeration characteristics;3) The crucial reasons for spatial separation of production and sales in China’s automobile market include implementation of purchase restrictions in more and more cities, gradual consolidation of spatial pattern of automobile production, and the fact that some automobile production areas are far away from consumer market;4) The provincial spatial weighted average centers of automobile sales are mainly distributed in southeast Henan, and show a trend of moving to the southwest;5) The estimated coefficients of factors such as GDP, financial added value, the proportion of highway, the volume of highway freight, and implementation of automobile consumption incentive policies are all significantly positive, and some factors have positive spatial spillover effects. Existing research on the automobile market lacks analysis based on long-time series data. This study uses long-time series data to provide a certain reference for future research in related directions.
基金Supported by the National Natural Science Foundation of China(No.42130713)the Innovation Project of LREIS(No.O88RA205YA)the National Natural Science Foundation of China(No.42407621).
文摘Introduction:Depression among older adults has emerged as a critical public health concern in China.While previous studies have demonstrated spatial heterogeneity in the prevalence of depressive symptoms among elderly populations across China,the spatiotemporal evolution of this phenomenon remains inadequately explored.This study aimed to estimate city-level prevalence of depressive symptoms among elderly Chinese residents from 2013 to 2020 and analyze its spatial-temporal patterns.Methods:Data were obtained from the China Health and Retirement Longitudinal Study(CHARLS)surveys conducted in 2013,2015,2018,and 2020.The study employed sandwich estimation methodology to calculate prevalence rates,while global autocorrelation analysis was utilized to evaluate spatial patterns in the distribution of depressive symptoms.Results:The average prevalence of depressive symptoms among Chinese older adults demonstrated a consistent increase from 30.27%[95%confidence interval(CI):24.53%,36.02%]in 2013 to 37.79%(95%CI:31.01%,44.56%)in 2020.Higher prevalence rates were observed in cities across Southwest,Northwest,and Central China,although no significant spatial aggregation was detected.Conclusions:The prevalence of depressive symptoms among older adults in China showed a substantial increase between 2013 and 2020.Enhanced preventive measures and interventions are particularly needed to improve mental well-being among elderly populations in China’s western and central regions.
基金the National Natural Science Foundation of China(72071022)Chongqing Construction Science and Technology Plan Project(2022-0213).
文摘Given the significance of cities as key execution units in carbon reduction initiatives,their role is crucial for the building sector and for China to achieve its“carbon peak and carbon neutrality”goals.Based on historical data on carbon emissions in the municipal-level building sector,this study employs spatiotemporal analysis models—such as Moran’s Index,kernel density estimation,and center of gravity migration analysis—to capture the spatial heterogeneity and dynamic evolution of carbon emissions from 2015 to 2020.By integrating an extended Kaya identity with the k-means clustering algorithm and embedding a machine learning algorithm with optimal test performance,the study identifies the heterogeneity in development types and influencing factors among different cities.The results indicate that carbon emissions in the municipal-level building sector across Chinese cities increasingly concentrate on higher emission ranges.North China serves as the high-value center for carbon emissions,whereas Southwest China is the low-value center.Analysis of center of gravity migration trajectories reveals that factors such as energy consumption per unit of GDP significantly drive the growth of carbon emissions in the building sector,while the general public budget expenditure intensity exerts an inhibitory effect.Additionally,Chinese cities are classified into five distinct development types.Compared to traditional nonlinear models and other machine learning models,XGBoost achieves the best predictive performance for carbon emissions across of buildings different city types,with R^(2)values of 0.998,0.992,0.983,0.995,and 0.986.These findings underscore the need to develop differentiated carbon reduction strategies that align with the unique development characteristics and influencing factors of each city type.
基金The National Natural Science Foundation of China(41261018,72263032)The Key Project of Yunnan Province Applied Basic Research Program(202501AS070166)。
文摘With the rapid development of urbanization and industrialization in China,the expansion of construction land and irrational utilization of cultivated land have led to issues such as cultivated land marginalization,extensive use,non-grain conversion,and non-agriculturalization.These issues are a major threat to sustainable agricultural development,but existing research suffers from limitations including failure to assess the multifunctionality of cultivated land(MCL)from the perspective of sustainable agricultural development.This study constructed an agricultural production function(APF)-social security function(SSF)-ecological maintenance function(EMF)-landscape aesthetic function(LAF)classification system.Using this comprehensive evaluation model,the MCL values for typical provinces in southwestern mountainous areas of China(Guizhou,Sichuan,and Yunnan)were calculated in detail,and their spatiotemporal evolutionary characteristics were explored.Concurrently,the Spearman rank correlation coefficient,geographically weighted regression(GWR)and redundancy model were used to deeply explore the relationships among cultivated land functions and their influencing factors.The results showed three important points.(1)Over the past two decades,the comprehensive values and four sub-functional values of cultivated land in southwestern mountainous areas have shown increasing trends in the order of SSF>EMF>LAF>APF.The values and rates of change of each sub-functional value show obvious spatial variation.However,the spatial gap in cultivated land functions has adverse effects on sustainable agricultural development.(2)There are clear correlations between each pair of the four major functions of cultivated land during the study period,and the number of results reaching significance among the six correlations between the four main cultivated land functions increased significantly from 2000 to 2020.Simultaneously,there are noticeable spatiotemporal differences in the trade-offs and synergies among the MCLs.(3)The development of MCL is most significantly influenced by socioeconomic factors such as the per capita net income of rural residents.Therefore,formulating reasonable land protection policies is imperative for promoting the sustainable development of agriculture.The results of this study can provide guidance for the rational layout and coordinated development of MCL space,for promoting sustainable agricultural development and ensuring food security.
基金The National Social Science Foundation Art Project of China(21BH157)。
文摘Based on data from Beijing museums spanning 1980 to 2020,this study employs spatial analysis methods such as geographical concentration index,imbalance index,kernel density and standard deviation ellipse characterize the temporal and spatial evolution of Beijing museums and analyze their influencing factors.The re-search shows that the museum development in Beijing has undergone three stages:a slow start,high-speed de-velopment and high-quality upgrading.The development of cultural relics and industrial museums tends towards balance,and the market-oriented development of museums continues to improve.The“single core”concentration distribution of Beijing museums is prominent,showing a typical“center edge”distribution with a trend of new core formation during expansion.Temporally,Beijing museums exhibit an inverted“L”evolution pattern,trending from north to east with Haidian and Chaoyang districts poised to become new centers.Distribution across intervals is uneven,yet the overall pattern is evolving towards a balanced distribution.The research on factors influencing the spatial distribution of museums,including population,resources,economy,and transportation,innovatively intro-duces educational factors.It shows that Beijing museums are transforming from“population driven”and“resource driven”to“education driven”over time.
基金financially supported by the Second Tibetan Plateau Scientific Expedition and Research Program of China(Grant No.2019QZKK0905)the Youth Fund of Shanxi Provincial Science and Technology Department of China(GrantNo.202103021223200)the Natural Science Foundation of Shaanxi Province,China(Grant No.2024JC-YBMS-314).
文摘The shear behavior of intact loess is intricately linked to the spatiotemporal evolution of its mesoscopic characteristics.Understanding this relationship is crucial for comprehending and preventing loess landslides.To systematically investigate this connection,our study conducted triaxial shear tests on both Malan loess and Lishi loess,encompassing variations in confining pressures.Additionally,nondestructive,real-time CT observations were employed to track the dynamic evolution of loess mesostructures.The experimental findings illuminate significant insights.The Malan loess exhibits strain hardening during shearing,with the degree of hardening exhibiting an increase in tandem with rising confining pressure.Conversely,the Lishi loess manifests a transition from strain softening to strain hardening as confining pressure increases.Under elevated confining pressure,the specimen undergoes structural damage while concurrently forming a denser configuration through particle friction and rearrangement,leading to strain hardening and volume reduction.In contrast,the central portion of the specimen exhibits heightened sensitivity to deformation under low confining pressures.Gradual crack expansion,emanating from the center and progressing towards the ends,results in progressive specimen destruction and a concomitant reduction in stress.On a macroscopic level,the specimen undergoes expansion at its center while contracting at its ends.The findings of this study unveil the intricate mechanisms governing loess deformation in the presence of varying confining pressures,thereby contributing significantly to our understanding of loess landslide formation and providing a robust theoretical framework for preventive measures.
