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
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
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
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
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
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
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 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
Identifying the spatiotemporal evolution characteristics of rural settlements and their driving factors is of great significance to layout optimization of rural settlements,intensive and economical use of rural land,a...Identifying the spatiotemporal evolution characteristics of rural settlements and their driving factors is of great significance to layout optimization of rural settlements,intensive and economical use of rural land,and preparation of land space planning.Focusing on the mountain-plain transitional zone of Dujiangyan City,China,as the study area,this paper employs methods including landscape pattern index,kernel density estimation,average nearest neighbor index,and Geodetector to quantitatively analyze the spatiotemporal layout evolution characteristics of rural settlements and relevant driving factors in Dujiangyan City over the last decade.The four main findings are as follows.First,land use area of rural settlements and the quantity of patches in Dujiangyan exhibited synchronous changes during 2005-2015.Total class area(CA)increased from 6161.43 to 7265.43 hm^(2),then declined to 7043.01 hm^(2),and the number of patches(NP)increased from 16543 to 26018,and then declined to 25890.Second,the maximum kernel density estimation values in the east and southeast of Dujiangyan City increased remarkably from 48.34 to 74.69 per hm^(2) during 2005-2010.Third,the average nearest neighbor index of rural settlements continually decreased in the foregoing 10 years,indicating a higher concentration of rural settlements.Finally,production and living conditions are the main driving factors of dynamic change in land use in rural settlements,while the impact of socio-economic factors is relatively smaller.Among others,the p-value of road accessibility is 0.057,and the impact p-value of land slope is 0.035.展开更多
An exact analytic expression for an ultrashort hollow-Airy wave packet is presented beyond the slowly varying envelope approximation. The hollow-Airy wave packet combines the hollow-Gaussian beam in the spatial domain...An exact analytic expression for an ultrashort hollow-Airy wave packet is presented beyond the slowly varying envelope approximation. The hollow-Airy wave packet combines the hollow-Gaussian beam in the spatial domain and the Airy pulse in the temporal domain. The spatiotemporal propagation dynamics of the ultrashort hollow- Airy pulse are analyzed by the numerical simulations. During the propagation in free space, the spatial intensity profile evolves from hollow-Gaussian to Gaussian shape; the temporal intensity profile retains Airy shape over several Rayleigh ranges. The acceleration property of the ultrashort Airy pulse is also demonstrated.展开更多
There are significant differences between urban and rural bed-and-breakfasts(B&Bs)in terms of customer positioning,economic strength and spatial carrier.Accurately identifying the differences in spatial characteri...There are significant differences between urban and rural bed-and-breakfasts(B&Bs)in terms of customer positioning,economic strength and spatial carrier.Accurately identifying the differences in spatial characteristics and influencing factors of each type,is essential for creating urban and rural B&B agglomeration areas.This study used density-based spatial clustering of applications with noise(DBSCAN)and the multi-scale geographically weighted regression(MGWR)model to explore similarities and differences in the spatial distribution patterns and influencing factors for urban and rural B&Bs on the Jiaodong Peninsula of China from 2010 to 2022.The results showed that:1)both urban and rural B&Bs in Jiaodong Peninsula went through three stages:a slow start from 2010 to 2015,rapid development from 2015 to 2019,and hindered development from 2019 to 2022.However,urban B&Bs demonstrated a higher development speed and agglomeration intensity,leading to an increasingly evident trend of uneven development between the two sectors.2)The clustering scale of both urban and rural B&Bs continued to expand in terms of quantity and volume.Urban B&B clusters characterized by a limited number,but a higher likelihood of transitioning from low-level to high-level clusters.While the number of rural B&B clusters steadily increased over time,their clustering scale was comparatively lower than that of urban B&Bs,and they lacked the presence of high-level clustering.3)In terms of development direction,urban B&B clusters exhibited a relatively stable pattern and evolved into high-level clustering centers within the main urban areas.Conversely,rural B&Bs exhibited a more pronounced spatial diffusion effect,with clusters showing a trend of multi-center development along the coastline.4)Transport emerged as a common influencing factor for both urban and rural B&Bs,with the density of road network having the strongest explanatory power for their spatial distribution.In terms of differences,population agglomeration had a positive impact on the distribution of urban B&Bs and a negative effect on the distribution of rural B&Bs.Rural B&Bs clustering was more influenced by tourism resources compared with urban B&Bs,but increasing tourist stay duration remains an urgent issue to be addressed.The findings of this study could provide a more precise basis for government planning and management of urban and rural B&B agglomeration areas.展开更多
In China, rural settlements are usually multifunctional complex of natural societies and they also play important productive function. This study explored the spatiotemporal evolution of the productive function of thr...In China, rural settlements are usually multifunctional complex of natural societies and they also play important productive function. This study explored the spatiotemporal evolution of the productive function of three rural settlements, i.e.,Hetaoyuan, Dawengshan, and Gaoqiao, in the Yimeng Mountain in Shandong province of eastern China.Residents lived in this three types of rural settlements were all involved in agricultural production(i.e., grain threshing, drying and storage), which had remained dominant in Hetaoyuan. Dawengshan became an industrial-oriented settlement, while Gaoqiao became a commercial-oriented settlement. This evolution was reflected in the livelihood strategy changes of rural households and the transition of rural settlements changes. The choice of livelihood strategy was affected by the livelihood assets and policies, which resulted in the spatiotemporal evolution of the productive function of rural settlements. This study can provide references for the implementation and adjustment of rural residential land consolidation policies and the improvement of production and the quality of rural life in future.展开更多
High-quality development of marine fisheries provides an important advantage for China to build itself into a maritime power and implement the Blue Granary Plan effectively.Based on the concepts of‘new development’,...High-quality development of marine fisheries provides an important advantage for China to build itself into a maritime power and implement the Blue Granary Plan effectively.Based on the concepts of‘new development’,‘food security’,and the six dimensions of‘openness,innovation,coordination,green,sharing,and security’,in this study,we established an evaluation index system for the high-quality development of China’s marine fishery sector.We applied the entropy method to evaluate the high-quality development level of China’s marine fishery sector from 2000 to 2016 and explored its spatial and temporal evolution rules.Our results indicated that:1)from 2000 to 2016,China’s marine fishery sector was in the primary stage of high-quality development;2)spatially,the highquality development of marine fisheries showed an upward trend in all provinces,autonomous regions,and municipalities in the country(not including Hong Kong,Macao and Taiwan of China),and with time,the distribution pattern changed from single to multi-polarization;3)temporally,the development level of high-quality marine fisheries fluctuated during the study period.From 2000 to 2010,the growth rate in openness was relatively slow,but after 2010,it increased rapidly.Notably,innovation is the driving force for high-quality development.The green and security factors provide a solid guarantee for high-quality development.In the high-quality development of a region,economic development is better coordinated,and the distribution of benefits is more inclusive.This study provides a theoretical basis to formulate effective marine fishery policies for the high-quality development of the marine fishery sector in China.Exploring the high-quality development and evolution process of marine fishery is conducive to promoting the sustainable development of marine fishery industry,ensuring marine fishery food security,and alleviating global food crisis.展开更多
The Chaobai River Basin,which is a crucial ecological barrier and primary water source area within the Beijing-Tianjin-Hebei region,possesses substantial ecological significance.The gross ecosystem product(GEP)in the ...The Chaobai River Basin,which is a crucial ecological barrier and primary water source area within the Beijing-Tianjin-Hebei region,possesses substantial ecological significance.The gross ecosystem product(GEP)in the Chaobai River Basin is a reflection of ecosystem conditions and quantifies nature’s contributions to humanity,which provides a basis for basin ecosystem service management and decision-making.This study investigated the spatiotemporal evolution of GEP in the upper Chaobai River Basin and explored the driving factors influencing GEP spatial differentiation.Ecosystem patterns from 2005 to 2020 were analyzed,and GEP was calculated for 2005,2010,2015,and 2020.The driving factors influencing GEP spatial differentiation were identified using the optimal parameter-based geographical detector(OPGD)model.The key findings are as follows:(1)From 2005 to 2020,the main ecosystem types were forest,grassland,and agriculture.Urban areas experienced significant changes,and conversions mainly occurred among urban,water,grassland and agricultural ecosystems.(2)Temporally,the GEP in the basin increased from 2005 to 2020,with regulation services dominating.At the county(district)scale,GEP exhibited a north-west-high and south-east-low pattern,showing spatial differences between per-unit-area GEP and county(district)GEP,while the spatial variations in per capita GEP and county(district)GEP were similar.(3)Differences in the spatial distribution of GEP were influenced by regional natural geographical and socioeconomic factors.Among these factors,gross domestic product,population density,and land-use degree density contributed significantly.Interactions among different driving forces noticeably impacted GEP spatial differentiation.These findings underscore the necessity of incorporating factors such as population density and the intensity of land-use development into ecosystem management decision-making processes in the upper reaches of the Chaobai River Basin.Future policies should be devised to regulate human activities,thereby ensuring the stability and enhancement of GEP.展开更多
In the 21 st century, economic interdependence between countries has gradually become an important source of state power. Globalization and the rise of China’s economy have had a significant impact on other economies...In the 21 st century, economic interdependence between countries has gradually become an important source of state power. Globalization and the rise of China’s economy have had a significant impact on other economies around the world. China’s economic influence is becoming more and more important. On the basis of the sensitivity dependence and vulnerability dependence of asymmetric interdependence theory, the economic spillover between countries is selected to construct a quantitative model to measure economic power. This paper analyzes the evolution of China’s economic power both in time and space from 2000 to 2014. Four conclusions were drawn from the study: 1) The spatial spillover effect of China’s economy on other countries has been continuously growing since the beginning of the 21 st century, which has brought about the rapid increase in China’s economic power;2) China’s economic power has been significantly strengthened both in intensity and scope, having expanded from the surrounding countries to the whole world. In 2014, China had a high amount of economic power over 18 countries from the 41 main countries in the world, compared to 2 in 2000;3) China’s power in terms of sensitivity dependence takes on an evolutionary trend from point distribution to flaky growth, and it shows a process ‘from point to line’ from the aspect of spatial diffusion. Furthermore, China’s power in terms of vulnerability dependence shows a trend that extends from the surrounding countries to European and South American countries;4) comprehensively, China’s power in terms of vulnerability dependence is higher than that of sensitivity dependence, and the spatial distribution pattern demonstrates a process from centralization to decentralization from 2000 to 2014.展开更多
Green development is an important issue of sustainable development in China.Due to the relatively backward economy and the fragile ecological environment,restricted development zones need to embrace green development....Green development is an important issue of sustainable development in China.Due to the relatively backward economy and the fragile ecological environment,restricted development zones need to embrace green development.Taking 38 counties in Jilin Province as the empirical research objects,and based on cross-sectional data for each county in 2005,2010,and 2015,we accurately depicted the spatiotemporal evolutionary characteristics of green development efficiency(GDE)in restricted development zones of Jilin Province using the slacks-based measure-data envelope analysis(SBM-DEA)model.Moreover,the factors that influence GDE were further analyzed using the Tobit model.We found that:first,GDE showed a V-shaped trend in restricted development zones of Jilin Province.The differences in GDE in the eastern,central,and western Jilin Province increased gradually.Second,76%of counties in the restricted development zones had high or higher efficiencies.The resource-based cities were the main areas with low or lower GDE.Third,the economic development level was the core factor affecting GDE.Urbanization level had a significant negative effect on GDE in the restricted development zones.The effect of technological innovation level on GDE fluctuated,and we found that a‘backward mechanism’of technological innovation was beginning to form.Industrial structure and environmental governance had no significant effects on GDE.展开更多
This article presents the experimental investigation on instabilities of thermocapillary-buoyancy convection in the transition process in an open rectangular liquid layer subject to a horizontal temperature gradient. ...This article presents the experimental investigation on instabilities of thermocapillary-buoyancy convection in the transition process in an open rectangular liquid layer subject to a horizontal temperature gradient. In the experimental run,an infrared thermal imaging system was constructed to observe and record the surface wave of the rectangular liquid layer. It was found that there are distinct convection longitudinal rolls in the flow field in the thermocapillary-buoyancy convection transition process. There are different wave characterizations for liquid layers with different thicknesses. For sufficiently thin layers, oblique hydrothermal waves are observed, which was predicted by the linear-stability analysis of Smith & Davis in 1983. For thicker layers, the surface flow is distinct and intensified, which is because the buoyancy convection plays a dominant role and bulk fluid flow from hot wall to cold wall in the free surface of liquid layers. In addition, the spatiotemporal evolution analysis has been carried out to conclude the rule of the temperature field destabilization in the transition process.展开更多
With the more complete acoustic emission(AE)catalog improved by the multi-channel AE matched-filter technique(MFT),we study the spatiotemporal evolution of the AE activities after laboratory stick-slip events incorpor...With the more complete acoustic emission(AE)catalog improved by the multi-channel AE matched-filter technique(MFT),we study the spatiotemporal evolution of the AE activities after laboratory stick-slip events incorporate with the slip data recorded by displacement transducers on an^1.5 m granite fault.The results show that the number of the AE events identified by MFT is about 9 times larger than that of the traditional method.A logarithmic expansion of early AE events along the fault strike is observed as a function of time,whereas the fault does not slip in the same manner.Thus,we related the expansion of the early AE events along the fault to the stress transfer caused by the adjacent AE events.Moreover,there is a good correlation between the cumulative number of the later AE events and the amount of fault slip.It suggests that the stress change caused by the continuous slip of the simulated fault after the stick-slip events response for the later AE events near or on the simulated fault.展开更多
Urbanization interacts with land use through resource consumption and space en-croachment.Clarifying the spatial correlations of the interactive relationship between urbaniza-tion and land use,along with their spatiot...Urbanization interacts with land use through resource consumption and space en-croachment.Clarifying the spatial correlations of the interactive relationship between urbaniza-tion and land use,along with their spatiotemporal dynamics,is of vital importance for address-ing the complex interplay between urban development and land resources and identifying re-gional differences.However,previous studies have not sufficiently explored these issues.Herein,we introduce a coupling coordination degree(CCD)model and present the results of exploratory spatiotemporal analyses involving in-depth investigation of the CcD between ur-banization quality and land-use intensity in 290 Chinese cities.The results demonstrate that the CcD for most cities was at the transition-period or basic-coordination stage.The dynamics of the spatial correlation of the CCD was found to increase from the east to the central and west-ern regions,but this was found to decline overall.The movement direction and spatial de-pendence of the local spatial structure of the CcD exerted a dominant synergistic effect.The transition of the spatial correlation was mainly Type I(stable local and neighboring morphology),showing strong transfer inertia,path dependence,and locking features.Dynamic transitions occurred more in central and eastern cities.The results suggest that more cross-city coopera-tion could contribute to moderate land-resource exploitation for high-quality urbanization.展开更多
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.
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(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.
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.
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This study was supported by the Chinese Ministry of Education Humanities and Social Sciences Research Youth Fund Project(Grant No.19YJCZH051)the Sichuan Province Social Science "13th Five-Year Plan" 2018 Youth Project(Grant No.SC18C033)the Sichuan Provincial Department of Education Natural Science Key Project(Grant No.18ZA0400).
文摘Identifying the spatiotemporal evolution characteristics of rural settlements and their driving factors is of great significance to layout optimization of rural settlements,intensive and economical use of rural land,and preparation of land space planning.Focusing on the mountain-plain transitional zone of Dujiangyan City,China,as the study area,this paper employs methods including landscape pattern index,kernel density estimation,average nearest neighbor index,and Geodetector to quantitatively analyze the spatiotemporal layout evolution characteristics of rural settlements and relevant driving factors in Dujiangyan City over the last decade.The four main findings are as follows.First,land use area of rural settlements and the quantity of patches in Dujiangyan exhibited synchronous changes during 2005-2015.Total class area(CA)increased from 6161.43 to 7265.43 hm^(2),then declined to 7043.01 hm^(2),and the number of patches(NP)increased from 16543 to 26018,and then declined to 25890.Second,the maximum kernel density estimation values in the east and southeast of Dujiangyan City increased remarkably from 48.34 to 74.69 per hm^(2) during 2005-2010.Third,the average nearest neighbor index of rural settlements continually decreased in the foregoing 10 years,indicating a higher concentration of rural settlements.Finally,production and living conditions are the main driving factors of dynamic change in land use in rural settlements,while the impact of socio-economic factors is relatively smaller.Among others,the p-value of road accessibility is 0.057,and the impact p-value of land slope is 0.035.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61475139 and 11174249the National HighTechnology Research and Development of China under Grant No 2011AA060504the Fundamental Research Funds for the Central Universities under Grant No 2014FZA3002
文摘An exact analytic expression for an ultrashort hollow-Airy wave packet is presented beyond the slowly varying envelope approximation. The hollow-Airy wave packet combines the hollow-Gaussian beam in the spatial domain and the Airy pulse in the temporal domain. The spatiotemporal propagation dynamics of the ultrashort hollow- Airy pulse are analyzed by the numerical simulations. During the propagation in free space, the spatial intensity profile evolves from hollow-Gaussian to Gaussian shape; the temporal intensity profile retains Airy shape over several Rayleigh ranges. The acceleration property of the ultrashort Airy pulse is also demonstrated.
基金Under the auspices of National Social Science Foundation of China (No.21BJY202)。
文摘There are significant differences between urban and rural bed-and-breakfasts(B&Bs)in terms of customer positioning,economic strength and spatial carrier.Accurately identifying the differences in spatial characteristics and influencing factors of each type,is essential for creating urban and rural B&B agglomeration areas.This study used density-based spatial clustering of applications with noise(DBSCAN)and the multi-scale geographically weighted regression(MGWR)model to explore similarities and differences in the spatial distribution patterns and influencing factors for urban and rural B&Bs on the Jiaodong Peninsula of China from 2010 to 2022.The results showed that:1)both urban and rural B&Bs in Jiaodong Peninsula went through three stages:a slow start from 2010 to 2015,rapid development from 2015 to 2019,and hindered development from 2019 to 2022.However,urban B&Bs demonstrated a higher development speed and agglomeration intensity,leading to an increasingly evident trend of uneven development between the two sectors.2)The clustering scale of both urban and rural B&Bs continued to expand in terms of quantity and volume.Urban B&B clusters characterized by a limited number,but a higher likelihood of transitioning from low-level to high-level clusters.While the number of rural B&B clusters steadily increased over time,their clustering scale was comparatively lower than that of urban B&Bs,and they lacked the presence of high-level clustering.3)In terms of development direction,urban B&B clusters exhibited a relatively stable pattern and evolved into high-level clustering centers within the main urban areas.Conversely,rural B&Bs exhibited a more pronounced spatial diffusion effect,with clusters showing a trend of multi-center development along the coastline.4)Transport emerged as a common influencing factor for both urban and rural B&Bs,with the density of road network having the strongest explanatory power for their spatial distribution.In terms of differences,population agglomeration had a positive impact on the distribution of urban B&Bs and a negative effect on the distribution of rural B&Bs.Rural B&Bs clustering was more influenced by tourism resources compared with urban B&Bs,but increasing tourist stay duration remains an urgent issue to be addressed.The findings of this study could provide a more precise basis for government planning and management of urban and rural B&B agglomeration areas.
基金supported by the National Natural Science Foundation of China(Grant Nos.41671519 and 41771560)
文摘In China, rural settlements are usually multifunctional complex of natural societies and they also play important productive function. This study explored the spatiotemporal evolution of the productive function of three rural settlements, i.e.,Hetaoyuan, Dawengshan, and Gaoqiao, in the Yimeng Mountain in Shandong province of eastern China.Residents lived in this three types of rural settlements were all involved in agricultural production(i.e., grain threshing, drying and storage), which had remained dominant in Hetaoyuan. Dawengshan became an industrial-oriented settlement, while Gaoqiao became a commercial-oriented settlement. This evolution was reflected in the livelihood strategy changes of rural households and the transition of rural settlements changes. The choice of livelihood strategy was affected by the livelihood assets and policies, which resulted in the spatiotemporal evolution of the productive function of rural settlements. This study can provide references for the implementation and adjustment of rural residential land consolidation policies and the improvement of production and the quality of rural life in future.
基金Under the auspices of the National Natural Science Foundation of China(No.41976207,42076222,42071159)。
文摘High-quality development of marine fisheries provides an important advantage for China to build itself into a maritime power and implement the Blue Granary Plan effectively.Based on the concepts of‘new development’,‘food security’,and the six dimensions of‘openness,innovation,coordination,green,sharing,and security’,in this study,we established an evaluation index system for the high-quality development of China’s marine fishery sector.We applied the entropy method to evaluate the high-quality development level of China’s marine fishery sector from 2000 to 2016 and explored its spatial and temporal evolution rules.Our results indicated that:1)from 2000 to 2016,China’s marine fishery sector was in the primary stage of high-quality development;2)spatially,the highquality development of marine fisheries showed an upward trend in all provinces,autonomous regions,and municipalities in the country(not including Hong Kong,Macao and Taiwan of China),and with time,the distribution pattern changed from single to multi-polarization;3)temporally,the development level of high-quality marine fisheries fluctuated during the study period.From 2000 to 2010,the growth rate in openness was relatively slow,but after 2010,it increased rapidly.Notably,innovation is the driving force for high-quality development.The green and security factors provide a solid guarantee for high-quality development.In the high-quality development of a region,economic development is better coordinated,and the distribution of benefits is more inclusive.This study provides a theoretical basis to formulate effective marine fishery policies for the high-quality development of the marine fishery sector in China.Exploring the high-quality development and evolution process of marine fishery is conducive to promoting the sustainable development of marine fishery industry,ensuring marine fishery food security,and alleviating global food crisis.
基金the National Key Research and Development Program of China(No.2022YFF1301804)the Beijing Municipal Education Commission through the Innovative Transdisciplinary Program“Ecological Restoration Engineering”(No.GJJXK210102).
文摘The Chaobai River Basin,which is a crucial ecological barrier and primary water source area within the Beijing-Tianjin-Hebei region,possesses substantial ecological significance.The gross ecosystem product(GEP)in the Chaobai River Basin is a reflection of ecosystem conditions and quantifies nature’s contributions to humanity,which provides a basis for basin ecosystem service management and decision-making.This study investigated the spatiotemporal evolution of GEP in the upper Chaobai River Basin and explored the driving factors influencing GEP spatial differentiation.Ecosystem patterns from 2005 to 2020 were analyzed,and GEP was calculated for 2005,2010,2015,and 2020.The driving factors influencing GEP spatial differentiation were identified using the optimal parameter-based geographical detector(OPGD)model.The key findings are as follows:(1)From 2005 to 2020,the main ecosystem types were forest,grassland,and agriculture.Urban areas experienced significant changes,and conversions mainly occurred among urban,water,grassland and agricultural ecosystems.(2)Temporally,the GEP in the basin increased from 2005 to 2020,with regulation services dominating.At the county(district)scale,GEP exhibited a north-west-high and south-east-low pattern,showing spatial differences between per-unit-area GEP and county(district)GEP,while the spatial variations in per capita GEP and county(district)GEP were similar.(3)Differences in the spatial distribution of GEP were influenced by regional natural geographical and socioeconomic factors.Among these factors,gross domestic product,population density,and land-use degree density contributed significantly.Interactions among different driving forces noticeably impacted GEP spatial differentiation.These findings underscore the necessity of incorporating factors such as population density and the intensity of land-use development into ecosystem management decision-making processes in the upper reaches of the Chaobai River Basin.Future policies should be devised to regulate human activities,thereby ensuring the stability and enhancement of GEP.
基金the auspices of National Natural Science Foundation of China(No.41601161,41671169,41701174,71873040)the Youth Project of Humanities and Social Science Research of the Ministry of Education in China(No.17YJC790189,19YJC790011)+1 种基金the Innovation Team Project of Guangdong Universities(No.2018WCXTD005)the Key Base of Humanities and Social Science Research of Guangdong Universities(No.2019WZJD004)。
文摘In the 21 st century, economic interdependence between countries has gradually become an important source of state power. Globalization and the rise of China’s economy have had a significant impact on other economies around the world. China’s economic influence is becoming more and more important. On the basis of the sensitivity dependence and vulnerability dependence of asymmetric interdependence theory, the economic spillover between countries is selected to construct a quantitative model to measure economic power. This paper analyzes the evolution of China’s economic power both in time and space from 2000 to 2014. Four conclusions were drawn from the study: 1) The spatial spillover effect of China’s economy on other countries has been continuously growing since the beginning of the 21 st century, which has brought about the rapid increase in China’s economic power;2) China’s economic power has been significantly strengthened both in intensity and scope, having expanded from the surrounding countries to the whole world. In 2014, China had a high amount of economic power over 18 countries from the 41 main countries in the world, compared to 2 in 2000;3) China’s power in terms of sensitivity dependence takes on an evolutionary trend from point distribution to flaky growth, and it shows a process ‘from point to line’ from the aspect of spatial diffusion. Furthermore, China’s power in terms of vulnerability dependence shows a trend that extends from the surrounding countries to European and South American countries;4) comprehensively, China’s power in terms of vulnerability dependence is higher than that of sensitivity dependence, and the spatial distribution pattern demonstrates a process from centralization to decentralization from 2000 to 2014.
基金Under the auspices of National Natural Science Foundation of China(No.41771138,41801105)。
文摘Green development is an important issue of sustainable development in China.Due to the relatively backward economy and the fragile ecological environment,restricted development zones need to embrace green development.Taking 38 counties in Jilin Province as the empirical research objects,and based on cross-sectional data for each county in 2005,2010,and 2015,we accurately depicted the spatiotemporal evolutionary characteristics of green development efficiency(GDE)in restricted development zones of Jilin Province using the slacks-based measure-data envelope analysis(SBM-DEA)model.Moreover,the factors that influence GDE were further analyzed using the Tobit model.We found that:first,GDE showed a V-shaped trend in restricted development zones of Jilin Province.The differences in GDE in the eastern,central,and western Jilin Province increased gradually.Second,76%of counties in the restricted development zones had high or higher efficiencies.The resource-based cities were the main areas with low or lower GDE.Third,the economic development level was the core factor affecting GDE.Urbanization level had a significant negative effect on GDE in the restricted development zones.The effect of technological innovation level on GDE fluctuated,and we found that a‘backward mechanism’of technological innovation was beginning to form.Industrial structure and environmental governance had no significant effects on GDE.
基金Project supported by the Strategic Priority Research Program on Space Science,Chinese Academy of Sciences:SJ-10 Recoverable Scientific Experiment Satellite(Grant Nos.XDA04020405 and XDA04020202-05)the China Manned Space Engineering program(TG-2)+1 种基金Cooperative Research Project between China and Russiathe National Natural Science Foundation of China(Grant No.11372328)
文摘This article presents the experimental investigation on instabilities of thermocapillary-buoyancy convection in the transition process in an open rectangular liquid layer subject to a horizontal temperature gradient. In the experimental run,an infrared thermal imaging system was constructed to observe and record the surface wave of the rectangular liquid layer. It was found that there are distinct convection longitudinal rolls in the flow field in the thermocapillary-buoyancy convection transition process. There are different wave characterizations for liquid layers with different thicknesses. For sufficiently thin layers, oblique hydrothermal waves are observed, which was predicted by the linear-stability analysis of Smith & Davis in 1983. For thicker layers, the surface flow is distinct and intensified, which is because the buoyancy convection plays a dominant role and bulk fluid flow from hot wall to cold wall in the free surface of liquid layers. In addition, the spatiotemporal evolution analysis has been carried out to conclude the rule of the temperature field destabilization in the transition process.
基金supported by National Key R&D Program of China(2016YFE0109300)National Natural Science Foundation of China(41874061 and41802231)。
文摘With the more complete acoustic emission(AE)catalog improved by the multi-channel AE matched-filter technique(MFT),we study the spatiotemporal evolution of the AE activities after laboratory stick-slip events incorporate with the slip data recorded by displacement transducers on an^1.5 m granite fault.The results show that the number of the AE events identified by MFT is about 9 times larger than that of the traditional method.A logarithmic expansion of early AE events along the fault strike is observed as a function of time,whereas the fault does not slip in the same manner.Thus,we related the expansion of the early AE events along the fault to the stress transfer caused by the adjacent AE events.Moreover,there is a good correlation between the cumulative number of the later AE events and the amount of fault slip.It suggests that the stress change caused by the continuous slip of the simulated fault after the stick-slip events response for the later AE events near or on the simulated fault.
基金National Natural Science Foundation of China,No.42371286,No.42001206National Social Science Foundation of China,No.22CJY041+1 种基金The Key Laboratory for Law and Governance of the Ministry of Natural Resources,No.CUGFP-1904School of Public Administration at China University of Geosciences,No.CUGGG-2002。
文摘Urbanization interacts with land use through resource consumption and space en-croachment.Clarifying the spatial correlations of the interactive relationship between urbaniza-tion and land use,along with their spatiotemporal dynamics,is of vital importance for address-ing the complex interplay between urban development and land resources and identifying re-gional differences.However,previous studies have not sufficiently explored these issues.Herein,we introduce a coupling coordination degree(CCD)model and present the results of exploratory spatiotemporal analyses involving in-depth investigation of the CcD between ur-banization quality and land-use intensity in 290 Chinese cities.The results demonstrate that the CcD for most cities was at the transition-period or basic-coordination stage.The dynamics of the spatial correlation of the CCD was found to increase from the east to the central and west-ern regions,but this was found to decline overall.The movement direction and spatial de-pendence of the local spatial structure of the CcD exerted a dominant synergistic effect.The transition of the spatial correlation was mainly Type I(stable local and neighboring morphology),showing strong transfer inertia,path dependence,and locking features.Dynamic transitions occurred more in central and eastern cities.The results suggest that more cross-city coopera-tion could contribute to moderate land-resource exploitation for high-quality urbanization.