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中国西北干旱区土地沙漠化敏感性时空格局 认领
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作者 魏伟 郭泽呈 +5 位作者 石培基 周亮 王旭峰 李振亚 庞素菲 颉斌斌 《地理学报:英文版》 SCIE CSCD 2021年第1期46-68,共23页
Sensitivity assessment is useful for monitoring land desertification. Research into how to prevent and control desertification is also important. In the arid region of northwest China, desertification is becoming wors... Sensitivity assessment is useful for monitoring land desertification. Research into how to prevent and control desertification is also important. In the arid region of northwest China, desertification is becoming worse and is a serious problem that affects local sustainable development. Based on remote-sensing and geographic information system technology, this study establishes a 'soil-terrain-hydrology-climate-vegetation' desertification sensitivity comprehensive evaluation system to reflect the spatiotemporal changes of land desertification, and proposes a spatial distance model to calculate a desertification sensitivity index. The spatiotemporal change characteristics of land desertification sensitivity in northwest China are quantitatively assessed from 2000 to 2017. Moreover, the main driving factors are analyzed using the geographical detector method. The results show the following.(1) Terrain, soil, climate, vegetation and hydrology affect and restrict each other, and constitute the background conditions of the distributions and changes of sensitivity to desertification in northwest China.(2) Desertification sensitivity generally displays a low distribution characteristic on the periphery of the area and a high one in the interior. The low-sensitivity regions are mainly in the five major mountain ranges(Altai Mountains, Tianshan Mountains, Kunlun Mountains, Altun Mountains and Qilian Mountains), while the high-sensitivity regions are mainly in regions such as the Junggar Basin, the Tarim Basin and the Inner Mongolia Plateau, as well as the Taklimakan Desert, Badain Jaran Desert and Tengger Desert. The spatial distribution of desertification sensitivity is obviously regional, and the high-and low-sensitivity regions have clear boundaries and a concentrated distribution.(3) With regard to spatiotemporal evolution, changes in desertification sensitivity since 2000 have been predominantly stable, and the overall sensitivity has displayed a slowly decreasing trend, indicating that potential desertification regi 展开更多
关键词 desertification sensitivity spatiotemporal change geographical detector GIS northwest China
城市群地区环境胁迫的驱动因素与时空效应——来自京津冀地区的证据 认领
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作者 周侃 殷悦 +1 位作者 李会 申玉铭 《地理学报:英文版》 SCIE CSCD 2021年第1期91-110,共20页
Environmental stress is used as an indicator of the overall pressure on regional environmental systems caused by the output of various pollutants as a result of human activities. Based on the pollutant emissions and s... Environmental stress is used as an indicator of the overall pressure on regional environmental systems caused by the output of various pollutants as a result of human activities. Based on the pollutant emissions and socioeconomic databases of the counties in Beijing–Tianjin–Hebei region, this paper comprehensively calculates the environmental stress index(ESI) for the urban agglomeration using the entropy weight method(EWM) at the county scale and analyzes the spatiotemporal patterns and the differences among the four types of major functional zones(MFZ) for the period 2012–2016. In addition, the socioeconomic driving forces of environmental stress are quantitatively estimated using the geographically weighted regression(GWR) method based on the STIRPAT model framework. The results show that:(1) The level of environmental stress in the Beijing–Tianjin–Hebei region was significantly alleviated during that time period, with a decrease in ESI of 54.68% by 2016. This decrease was most significant in Beijing, Tangshan, Tianjin, Shijiazhuang, and other central urban areas, as well as the Binhai New Area. The level of environmental stress in counties decreased gradually from the central urban areas to the suburban areas, and the high-level stress counties were eliminated by 2016.(2) The spatial spillover effect of environmental stress increased further at the county scale from 2012 to 2016, and spatial locking and path dependence emerged in the cities of Tangshan and Tianjin.(3) Urbanized zones(development-optimized and development-prioritized zones) were the major areas bearing environmental pollution in the Beijing–Tianjin–Hebei region in that time period. The ESI accounted for 65.98% of the whole region, where there was a need to focus on the prevention and control of environmental pollution.(4) The driving factors of environmental stress at the county scale included population size and the level of economic development. In addition, the technical capacity of environmental waste disposal, the intensity 展开更多
关键词 environmental stress spatiotemporal effects driving factors urban agglomeration major functional zones(MFZ) Beijing–Tianjin–Hebei region
Effect of Hydrological Connectivity on Soil Carbon Storage in the Yellow River Delta Wetlands of China 认领
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作者 FENG Jiuge LIANG Jinfeng +3 位作者 LI Qianwei ZHANG Xiaoya YUE Yi GAO Junqin 《中国地理科学:英文版》 SCIE CSCD 2021年第2期197-208,共12页
Hydrological connectivity has significant effects on the functions of estuarine wetland ecosystem.This study aimed to examine the dynamics of hydrological connectivity and its impact on soil carbon pool in the Yellow ... Hydrological connectivity has significant effects on the functions of estuarine wetland ecosystem.This study aimed to examine the dynamics of hydrological connectivity and its impact on soil carbon pool in the Yellow River Delta,China.We calculated the hydrological connectivity based on the hydraulic resistance and graph theory,and measured soil total carbon and organic carbon under four different hydrological connectivity gradients(Ⅰ0‒0.03,Ⅱ0.03‒0.06,Ⅲ0.06‒0.12,Ⅳ0.12‒0.39).The results showed that hydrological connectivity increased in the north shore of the Yellow River and the south tidal flat from 2007 to 2018,which concentrated in the mainstream of the Yellow River and the tidal creek.High hydrological connectivity was maintained in the wetland restoration area.The soil total carbon storage and organic carbon storage significantly increased with increasing hydrological connectivity fromⅠtoⅢgradient and decreased inⅣgradient.The highest soil total carbon storage of 0‒30 cm depth was 5172.34 g/m2,and organic carbon storage 2764.31 g/m2inⅢgradient.The hydrological connectivity changed with temporal and spatial change during 2007‒2018 and had a noticeable impact on soil carbon storage in the Yellow River Delta.The results indicated that appropriate hydrological connectivity,i.e.0.08,could effectively promote soil carbon storage. 展开更多
关键词 coastal wetland hydrological connectivity soil carbon carbon storage spatiotemporal variation the Yellow River Delta
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Dissolved and emitted methane in the Poyang Lake 认领
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作者 WANG HaiZhen HUANG Rong +2 位作者 LI JiaRui CHEN Qian MA Tao 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2021年第1期203-212,共10页
Lake waters often act as important methane sources for global greenhouse gas emission, but it would be more complex as lakes are regulated by rivers. In this study, seasonal variations of dissolved and emitted methane... Lake waters often act as important methane sources for global greenhouse gas emission, but it would be more complex as lakes are regulated by rivers. In this study, seasonal variations of dissolved and emitted methane in the Poyang Lake, the largest freshwater lake in China, are investigated based on a specially designed monitoring. As a typical subtropical linking-to-river lake, the Poyang shows characteristics of the "lake" in wet season and the "river" in dry season alternatively over a year.Consequently, CH4 flux from the Poyang Lake to the Yangtze River closes to the highest in January due to concentrated dissolved CH4 and "river" effects in dry season, while CH4 flux to the atmosphere falls to the lowest in July because of intensified CH4 oxidization and diluted dissolved CH4 as well as "lake" effects in wet season. Overall, CH4 fluxes from Poyang Lake to the atmosphere and to the Yangtze River were 19 and 0.35 Gg CH4 yr-1, respectively. The Three Gorges Dam, the world’s largest dam in the Yangtze River, would further intensify this pattern, enhancing the transformation between "lake phase" and"river phase". This study also provides the paradigm for CH4 budget from other large lakes in similar situations around the world. 展开更多
关键词 CH4 spatiotemporal variation linking-to-river lake Poyang Lake
城市物流环境影响的时空解析 认领
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作者 袁泉 陈小鸿 《城市交通》 2021年第2期29-36,89,共9页
在供应链全球化和电子商务时代,城市物流需求不断增长,相关活动在高度异质性的城市空间中产生了日益突出的负外部性影响。基于物流与土地利用、生态环境之间的相互作用和联系,从不同的时间响应和反馈机制角度对物流环境影响进行分析和... 在供应链全球化和电子商务时代,城市物流需求不断增长,相关活动在高度异质性的城市空间中产生了日益突出的负外部性影响。基于物流与土地利用、生态环境之间的相互作用和联系,从不同的时间响应和反馈机制角度对物流环境影响进行分析和归纳。结合供应链管理和公共政策制定过程,探讨不同空间尺度物流环境影响治理的目标与途径。建议未来相关研究以时空关系及其变化过程作为评价和度量物流活动环境影响的重要方向之一,进一步依靠大数据应用等技术支持,探索城市物流在需求快速增长、环境空间资源有限、多利益主体博弈的背景下,面向以人为本的长期可持续发展目标的政策路径。 展开更多
关键词 城市物流 环境影响 时空尺度 可持续发展
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Delineation of an Urban Community Life Circle Based on a Machine-Learning Estimation of Spatiotemporal Behavioral Demand 认领
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作者 LI Chunjiang XIA Wanqu CHAI Yanwei 《中国地理科学:英文版》 SCIE CSCD 2021年第1期27-40,共14页
Delineating life circles is an essential prerequisite for urban community life circle planning. Recent studies combined the environmental contexts with residents’ global positioning system(GPS) data to delineate the ... Delineating life circles is an essential prerequisite for urban community life circle planning. Recent studies combined the environmental contexts with residents’ global positioning system(GPS) data to delineate the life circles. This method, however, is constrained by GPS data, and it can only be applied in the GPS surveyed communities. To address this limitation, this study developed a generalizable delineation method without the constraint of behavioral data. According to previous research, the community life circle consists of the walking-accessible range and internal structure. The core task to develop the generalizable method was to estimate the spatiotemporal behavioral demand for each plot of land to acquire the internal structure of the life circle, as the range can be delineated primarily based on environmental data. Therefore, behavioral demand estimation models were established through logistic regression and machine learning techniques, including decision trees and ensemble learning. The model with the lowest error rate was chosen as the final estimation model for each type of land. Finally, we used a community without GPS data as an example to demonstrate the effectiveness of the estimation models and delineation method. This article extends the existing literature by introducing spatiotemporal behavioral demand estimation models, which learn the relationships between environmental contexts, population composition and the existing delineated results based on GPS data to delineate the internal structure of the community life circle without employing behavioral data. Furthermore, the proposed method and delineation results also contributes to facilities adjustments and location selections in life circle planning, people-oriented transformation in urban planning, and activity space estimation of the population in evaluating and improving the urban policies. 展开更多
关键词 community life circle spatiotemporal behavioral demand demand estimation model decision tree ensemble learning
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Graph Laplacian Matrix Learning from Smooth Time-Vertex Signal 认领
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作者 Ran Li Junyi Wang +2 位作者 Wenjun Xu Jiming Lin Hongbing Qiu 《中国通信:英文版》 SCIE CSCD 2021年第3期187-204,共18页
In this paper,we focus on inferring graph Laplacian matrix from the spatiotemporal signal which is defined as“time-vertex signal”.To realize this,we first represent the signals on a joint graph which is the Cartesia... In this paper,we focus on inferring graph Laplacian matrix from the spatiotemporal signal which is defined as“time-vertex signal”.To realize this,we first represent the signals on a joint graph which is the Cartesian product graph of the time-and vertex-graphs.By assuming the signals follow a Gaussian prior distribution on the joint graph,a meaningful representation that promotes the smoothness property of the joint graph signal is derived.Furthermore,by decoupling the joint graph,the graph learning framework is formulated as a joint optimization problem which includes signal denoising,timeand vertex-graphs learning together.Specifically,two algorithms are proposed to solve the optimization problem,where the discrete second-order difference operator with reversed sign(DSODO)in the time domain is used as the time-graph Laplacian operator to recover the signal and infer a vertex-graph in the first algorithm,and the time-graph,as well as the vertex-graph,is estimated by the other algorithm.Experiments on both synthetic and real-world datasets demonstrate that the proposed algorithms can effectively infer meaningful time-and vertex-graphs from noisy and incomplete data. 展开更多
关键词 Cartesian product graph discrete secondorder difference operator Gaussian prior distribution graph Laplacian matrix learning spatiotemporal smoothness time-vertex signal
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A multi-task deep learning model for short-term taxi demand forecasting considering spatiotemporal dependences 认领
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作者 Huimin Luo Jianming Cai +2 位作者 Kunpeng Zhang Ruihang Xie Liang Zheng 《交通运输工程学报:英文版》 CSCD 2021年第1期83-94,共12页
Short-term taxi demand forecasting is of great importance to incentivize vacant cars moving from over-supply regions to over-demand regions,which can minimize the wait time for passengers and drivers.With the consider... Short-term taxi demand forecasting is of great importance to incentivize vacant cars moving from over-supply regions to over-demand regions,which can minimize the wait time for passengers and drivers.With the consideration of spatiotemporal dependences,this study proposes a multi-task deep learning(MTDL)model to predict short-term taxi demand in multi-zone level.The nonlinear Granger causality test is applied to explore the causality relationships among various traffic zones,and long short-term memory(LSTM)is used as the core neural unit to construct the framework of the multi-task deep learning model.In addition,several hyperparameter optimization methods(e.g.,grid search,random search,Bayesian optimization,hyperopt)are used to tune the model.Using the taxi trip data in New York City for validation,the multi-task deep learning model considering spatiotemporal dependences(MTDL*)is compared with the single-task deep learning model(STDL),the full-connected multi-task deep learning model(MTDL#)and other benchmark algorithms(such as LSTM,support vector machine(SVM)and k-nearest neighbors(k-NN)).The experiment results show that the proposed MTDL model is promising to predict short-term taxi demand in multi-zone level,the nonlinear Granger causality analysis is able to capture the spatiotemporal correlations among various traffic zones,and the Bayesian optimization is superior to the other three methods,which verified the feasibility and adaptability of the proposed method. 展开更多
关键词 Traffic engineering Short-term traffic prediction Deep learning Multi-task model Spatiotemporal dependences
Population migration across the Qinghai-Tibet Plateau:Spatiotemporal patterns and driving factors 认领
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作者 WANG Nan WANG Huimeng +3 位作者 DU Yunyan YI Jiawei LIU Zhang TU Wenna 《地理学报:英文版》 SCIE CSCD 2021年第2期195-214,共20页
Developing a comprehensive understanding of inter-city interactions is crucial for regional planning.We therefore examined spatiotemporal patterns of population migration across the Qinghai-Tibet Plateau(QTP)using mig... Developing a comprehensive understanding of inter-city interactions is crucial for regional planning.We therefore examined spatiotemporal patterns of population migration across the Qinghai-Tibet Plateau(QTP)using migration big data from Tencent for the period between 2015 and 2019.We initially used decomposition and breakpoint detection methods to examine time-series migration data and to identify the two seasons with the strongest and weakest population migration levels,between June 18th and August 18th and between October 8th and February 15th,respectively.Population migration within the former period was 2.03 times that seen in the latter.We then used a variety of network analysis methods to examine population flow directions as well as the importance of each individual city in migration.The two capital cities on the QTP,Lhasa and Xining,form centers for population migration and are also transfer hubs through which migrants from other cities off the plateau enter and leave this region.Data show that these two cities contribute more than 35%of total population migration.The majority of migrants tend to move within the province,particularly during the weakest migration season.We also utilized interactive relationship force and radiation models to examine the interaction strength and the radiating energy of each individual city.Results show that Lhasa and Xining exhibit the strongest interactions with other cities and have the largest radiating energies.Indeed,the radiating energy of the QTP cities correlates with their gross domestic product(GDP)(Pearson correlation coefficient:0.754 in the weakest migration season,WMS versus 0.737 in the strongest migration season,SMS),while changes in radiating energy correlate with the tourism-related revenue(Pearson correlation coefficient:0.685).These outcomes suggest that level of economic development and level of tourism are the two most important factors driving the QTP population migration.The results of this analysis provide critical clarification guidance regarding h 展开更多
关键词 Qinghai-Tibet Plateau population migration migration big data flow radiation model spatiotemporal interaction mode
Prediction of Spatiotemporal Evolution of Urban Traffic Emissions Based on Taxi Trajectories 认领
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作者 Zhen-Yi Zhao Yang Cao +1 位作者 Yu Kang Zhen-Yi Xu 《国际自动化与计算杂志:英文版》 EI CSCD 2021年第2期219-232,共14页
With the rapid increase of the amount of vehicles in urban areas,the pollution of vehicle emissions is becoming more and more serious.Precise prediction of the spatiotemporal evolution of urban traffic emissions plays... With the rapid increase of the amount of vehicles in urban areas,the pollution of vehicle emissions is becoming more and more serious.Precise prediction of the spatiotemporal evolution of urban traffic emissions plays a great role in urban planning and policy making.Most existing methods usually focus on estimating vehicle emissions at historical or current moments which cannot well meet the demands of future planning.Recent work has started to pay attention to the evolution of vehicle emissions at future moments using multiple attributes related to emissions,however,they are not effective and efficient enough in the combination and utilization of different inputs.To address this issue,we propose a joint framework to predict the future evolution of vehicle emissions based on the GPS trajectories of taxis with a multi-channel spatiotemporal network and the motor vehicle emission simulator(MOVES)model.Specifically,we first estimate the spatial distribution matrices with GPS trajectories through map-matching algorithms.These matrices can reflect the attributes related to the traffic status of road networks such as volume,speed and acceleration.Then,our multi-channel spatiotemporal network is used to efficiently combine three key attributes(volume,speed and acceleration)through the feature sharing mechanism and generate a precise prediction of them in the future period.Finally,we adopt an MOVES model to estimate vehicle emissions by integrating several traffic factors including the predicted traffic states,road networks and the statistical information of urban vehicles.We evaluate our model on the Xi′an taxi GPS trajectories dataset.Experiments show that our proposed network can effectively predict the temporal evolution of vehicle emissions. 展开更多
关键词 Vehicle emission prediction spatiotemporal gragh convolution GPS trajectories motor vehicle emission simulator(MOVES)model feature sharing
Visualization and analysis of local and distant population flows on the Qinghai-Tibet Plateau using crowd-sourced data 认领
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作者 XU Jun LIU Ju +1 位作者 XU Yang PEI Tao 《地理学报:英文版》 SCIE CSCD 2021年第2期231-244,共14页
Human migration between cities is one important aspect of spatial interaction that not only reflects urban attractiveness but also denotes interactions amongst agglomerations.We therefore implemented a web-based visua... Human migration between cities is one important aspect of spatial interaction that not only reflects urban attractiveness but also denotes interactions amongst agglomerations.We therefore implemented a web-based visualization system to analyze and interactively explore local and distant population flow patterns between cities on the Qinghai-Tibet Plateau(QTP).We utilized 2017 Tencent population flow data from which we initially constructed inbound and outbound vectors for cities on the QTP.We then used multidimensional scaling to examine and visualize migration patterns and similarities between cities.Results reveal the presence of six local and three distant human mobility patterns on the QTP as well as average summer monthly migrations more than twice the level of those in the winter. 展开更多
关键词 population flow VISUALIZATION Tencent location big data spatiotemporal pattern Qinghai-Tibet Plateau
Rapid Urbanization Induced Extensive Forest Loss to Urban Land in the Guangdong-Hong Kong-Macao Greater Bay Area, China 认领
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作者 YANG Chao LIU Huizeng +7 位作者 LI Qingquan CUI Aihong XIA Rongling SHI Tiezhu ZHANG Jie GAO Wenxiu ZHOU Xiang WU Guofeng 《中国地理科学:英文版》 SCIE CSCD 2021年第1期93-108,共16页
China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot ... China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot regions, the Guangdong-Hong KongMacao Greater Bay Area(GBA) has undergone a dramatic urban expansion. To better understand forest dynamics and protect forest ecosystem, revealing the processes, patterns and underlying drivers of forest loss is essential. This study focused on the spatiotemporal evolution and potential driving factors of forest loss in the GBA at regional and city level. The Landsat time-series images from 1987 to2017 were used to derive forest, and landscape metrics and geographic information system(GIS) were applied to implement further spatial analysis. The results showed that: 1) 14.86% of the total urban growth area of the GBA was obtained from the forest loss in1987–2017;meanwhile, the forest loss area of the GBA reached 4040.6 km2, of which 25.60%(1034.42 km2) was converted to urban land;2) the percentages of forest loss to urban land in Dongguan(19.14%), Guangzhou(18.35%) and Shenzhen(15.81%) were higher than those in other cities;3) the forest became increasingly fragmented from 1987–2007, and then the fragmentation decreased from2007 to 2017);4) the landscape responses to forest changes varied with the scale;and 5) some forest loss to urban regions moved from low-elevation and gentle-slope terrains to higher-elevation and steep-slope terrains over time, especially in Shenzhen and Hong Kong.Urbanization and industrialization greatly drove forest loss and fragmentation, and, notably, hillside urban land expansion may have contributed to hillside forest loss. The findings will help policy makers in maintaining the stability of forest ecosystems, and provide some new insights into forest management and conservation. 展开更多
关键词 forest loss to urban land urbanization spatiotemporal pattern remote sensing Guangdong-Hong Kong-Macao Greater Bay Area(GBA)
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地理大数据挖掘——目标、内涵与研究问题 认领
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作者 裴韬 宋辞 +5 位作者 郭思慧 舒华 刘亚溪 杜云艳 马廷 周成虎 《地理学报:英文版》 SCIE CSCD 2020年第2期251-266,共16页
The objective,connotations and research issues of big geodata mining were discussed to address its significance to geographical research in this paper.Big geodata may be categorized into two domains:big earth observat... The objective,connotations and research issues of big geodata mining were discussed to address its significance to geographical research in this paper.Big geodata may be categorized into two domains:big earth observation data and big human behavior data.A description of big geodata includes,in addition to the“5Vs”(volume,velocity,value,variety and veracity),a further five features,that is,granularity,scope,density,skewness and precision.Based on this approach,the essence of mining big geodata includes four aspects.First,flow space,where flow replaces points in traditional space,will become the new presentation form for big human behavior data.Second,the objectives for mining big geodata are the spatial patterns and the spatial relationships.Third,the spatiotemporal distributions of big geodata can be viewed as overlays of multiple geographic patterns and the characteristics of the data,namely heterogeneity and homogeneity,may change with scale.Fourth,data mining can be seen as a tool for discovery of geographic patterns and the patterns revealed may be attributed to human-land relationships.The big geodata mining methods may be categorized into two types in view of the mining objective,i.e.,classification mining and relationship mining.Future research will be faced by a number of issues,including the aggregation and connection of big geodata,the effective evaluation of the mining results and the challenge for mining to reveal“non-trivial”knowledge. 展开更多
关键词 BIG earth observation DATA BIG human behavior DATA GEOGRAPHICAL SPATIOTEMPORAL pattern SPATIOTEMPORAL HETEROGENEITY knowledge DISCOVERY
Accelerated Generation of Spatiotemporal Atlas through Fast Template Matching 认领
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作者 Lianjun Zhang Lifang Zhao Gang Liu 《电脑和通信(英文)》 2020年第1期16-27,共12页
A spatiotemporal atlas refers to a standard image sequence that represents the general motion pattern of the targeted anatomy across a group of subjects. Recent years have witnessed an increasing interest in using spa... A spatiotemporal atlas refers to a standard image sequence that represents the general motion pattern of the targeted anatomy across a group of subjects. Recent years have witnessed an increasing interest in using spatiotemporal atlas for scientific research and clinical applications in image processing, data analysis and medical imaging. However, the generation of spatiotemporal atlas is often time-consuming and computationally expensive due to the nonlinear image registration procedures involved. This research targets at accelerating the generation of spatiotemporal atlas by formulating the atlas generation procedure as a multi-level modulation (M-ary) classification problem. In particular, we have implemented a fast template matching method based on singular value decomposition, and applied it to generate high quality spatiotemporal atlas with reasonable time and computational complexity. The performance has been systematically evaluated on public accessible data sets. The results and conclusions hold promise for further developing advanced algorithms for accelerating generation of spatiotemporal atlas. 展开更多
关键词 SPATIOTEMPORAL ATLAS TEMPLATE MATCHING Classification
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Research on Spatiotemporal Variation of Soil Temperature in China from 1948 to 2018 认领
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作者 Mengyuan Zang Mengqing Geng +2 位作者 Feng Zhang Qiulan Wu Yong Liang 《环境保护(英文)》 2020年第8期570-584,共15页
The change of soil temperature can affect the regional climate, so it is of great significance to research the spatial and temporal evolution characteristics of regional soil temperature over a long period of time for... The change of soil temperature can affect the regional climate, so it is of great significance to research the spatial and temporal evolution characteristics of regional soil temperature over a long period of time for the research of the land-air interaction, climate change and ecological agricultural construction. We use the v2.0 and v2.1 data set combined with GLDAS and Noah models to analyze the spatiotemporal variation of temperature in soil layers of 0 - 200 cm in China during the period of 71 years from 1948 to 2018. Firstly, the Mann-Kendall test method is used to research the variation trend of soil temperature over the past 71 years in China and the spatial variation of these trends. Secondly, by calculating the spatiotemporal coefficient of variation (CV) of soil temperature, the spatial-temporal fluctuation of soil temperature in China is further studied and analyzed. Finally, the Hurst index is used to analyze the possible future trend of soil temperature in China. Based on these methods, we have drawn the following conclusions: 1) The soil temperature in most areas of northern China had an increasing trend, especially in the northeast China. The soil temperature in most of the south China had a decreasing trend. The temperature trends of the four soil layers had little difference, and it remained stable on the whole. 2) The regional difference of soil temperature in China remained stable before 1999, and decreased suddenly in 2000. After 2008, the regional difference increased. Compared with the previous period, the temperature in some areas increased or decreased abnormally. 3) The soil temperature in eastern, southeast China and Xinjiang had a relatively significant variation in the 71 years. From 0 - 10 cm soil surface to 100 - 200 cm soil bottom, the spatial difference of temperature gradually decreased, which was due to the fact that the soil temperature was more affected by the surface atmospheric temperature. 4) The soil temperature in the north and northwest of China will continue to grow, an 展开更多
关键词 China Soil Temperature Spatiotemporal Variation GLDAS MANN-KENDALL Hurst Index
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Spatio-Temporal Study of Toxic and Harmful Planktonic Taxa at Two Oceanic Sites Mehdia and Moulay Bousselham, Rabat Sale Kenitra Region, Morocco, between 2017 and 2018 认领
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作者 A. Hal Aberrhaman B. Bouhaddioui +1 位作者 L. A. Lrhorfi R. Bengueddour 《海洋科学期刊(英文)》 2020年第2期41-51,共11页
Phytoplankton is all cyanobacteria and microalgae (microscopic plants) present in surface water that may be carried by water currents. The study was conducted at two oceanic sites Mehdia and Moulay Bousselham, Rabat s... Phytoplankton is all cyanobacteria and microalgae (microscopic plants) present in surface water that may be carried by water currents. The study was conducted at two oceanic sites Mehdia and Moulay Bousselham, Rabat sale Kenitra region, Morocco, between 2017 and 2018. The objective of this study is to compare the spatiotemporal evolution of certain toxic planktonic species between the two sites. The planktonic species identified all have toxic potency but to varying degrees such as Alexandrium, Dinophysis, Gymnodinum, Pseudonitzschia and Proocentrum. The comparison of the abundance of these taxa in the two sites confirms that the Moulay Bousselham site is characterized by the presence of the most toxic planktonic species represented mainly by Pseudonitzschia in contrast the Mehdia site experienced an abundance of the Proocentrum kind. This situation requires a more detailed study of the essential causes of the proliferation of these species. 展开更多
关键词 Phytoplankton Surface Water TOXIC Power SPATIOTEMPORAL Evolution Mehdia Moulay Bousselham
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基于人口流动的广东省COVID-19疫情风险时空分析 认领
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作者 叶玉瑶 王长建 +4 位作者 张虹鸥 杨骥 刘郑倩 吴康敏 邓应彬 《地理学报:英文版》 SCIE CSCD 2020年第12期1985-2001,共17页
Population migration,especially population inflow from epidemic areas,is a key source of the risk related to the coronavirus disease 2019(COVID-19)epidemic.This paper selects Guangdong Province,China,for a case study.... Population migration,especially population inflow from epidemic areas,is a key source of the risk related to the coronavirus disease 2019(COVID-19)epidemic.This paper selects Guangdong Province,China,for a case study.It utilizes big data on population migration and the geospatial analysis technique to develop a model to achieve spatiotemporal analysis of COVID-19 risk.The model takes into consideration the risk differential between the source cities of population migration as well as the heterogeneity in the socioeconomic characteristics of the destination cities of population migration.It further incorporates a time-lag process based on the time distribution of the onset of the imported cases.In theory,the model will be able to predict the evolutional trend and spatial distribution of the COVID-19 risk for a certain time period in the future and provide support for advanced planning and targeted prevention measures.The research findings indicate the following:(1)The COVID-19 epidemic in Guangdong Province reached a turning point on January 29,2020,after which it showed a gradual decreasing trend.(2)Based on the time-lag analysis of the onset of the imported cases,it is common fora time interval to exist between case importation and illness onset,and the proportion of the cases with an interval of 1-14 days is relatively high.(3)There is evident spatial heterogeneity in the epidemic risk;the risk varies significantly between different areas based on their imported risk,susceptibility risk,and ability to prevent the spread.(4)The degree of connectedness and the scale of population migration between Guangdong’s prefecture-level cities and their counterparts in the source regions of the epidemic,as well as the transportation and location factors of the cities in Guangdong,have a significant impact on the risk classification of the cities in Guangdong.The first-tier cities-Shenzhen and Guangzhou-are high-risk regions.The cities in the Pearl River Delta that are adjacent to Shenzhen and Guangzhou,including Dongguan, 展开更多
关键词 population migration COVID-19 epidemic risk time-lag process spatiotemporal analysis
Spatial-Temporal Evolution Characteristics and Driving Factors of Agricultural Space in Jianghan Plain from the Perspective of “Three-Zone Space” 认领
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作者 Wei Wei Hao Xing 《生态学期刊(英文)》 2020年第2期62-76,共15页
Studying the agricultural spatial distribution characteristics of Jianghan Plain from 2000 to 2018 and its spatial-temporal transformation with ecological space and urban space is of great significance for optimizing ... Studying the agricultural spatial distribution characteristics of Jianghan Plain from 2000 to 2018 and its spatial-temporal transformation with ecological space and urban space is of great significance for optimizing the spatial structure of the country, enhancing the supply capacity of agricultural products, and ensuring food security. The research results show that during the period from 2000 to 2018, the agricultural spatial concentration in the area along the “Xiaogan-Jingzhou” link was relatively high, and the areas with large declines were mainly distributed in the flat areas between the Yangtze River and Han River;the space is continuously reduced by the occupation of ecological space and urban space, and ecological space and urban space have been improved respectively;agricultural space has been transformed into ecological space, and the largest urban space has been transformed. Ecological space has been transformed into agricultural space and urban space. Less urban space has been transformed into agricultural space and ecological space. 展开更多
关键词 Three-Zone SPACE Jianghan PLAIN Agricultural SPACE SPATIOTEMPORAL Evolution Driving Factors
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Spatiotemporal Analysis of Nodding Syndrome in Northern Uganda 1990-2014 认领
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作者 Kizito Ongaya Augustus Aturinde +4 位作者 Mahdi Farnaghi Ali Mansourian Gilbert Maiga Benedict Oyo Emily Bagarukayo 《健康(英文)》 2020年第2期180-193,共14页
The emergence of nodding syndrome (NS) in Northern Uganda has generated controversial views with respect to patterns, natural history, and aetiology of the disease which is yet unknown. This study explored spatial pat... The emergence of nodding syndrome (NS) in Northern Uganda has generated controversial views with respect to patterns, natural history, and aetiology of the disease which is yet unknown. This study explored spatial patterns of NS using spatial-temporal methods to establish its clustering patterns across both space and time. Village and year of NS onset for individual patients between the years 1990 and 2014 were entered as input for spatial and temporal analysis in the 6 districts in northern Uganda where it is prevalent. Our temporal results showed that NS onset started before the population was moved in Internally Displaced People’s (IDPs) camps. It also shows that NS continued to be reported during the IDPs and after people had left the IDPs. Our spatial and spatiotemporal analysis showed that two periods had persistent NS clusters. These were 2000-2004 and 2010-2014, coinciding with the period when the population was in the IDP camps and when the population was already out of the camps, respectively. Our conclusion is that the view of associating NS outbreak with living conditions in IDP camps is thus coincidental. We, therefore, contend that the actual aetiological factor of NS is still at large. 展开更多
关键词 Nodding SYNDROME SPATIOTEMPORAL SPATIAL ANALYSIS NORTHERN Uganda
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祁连山冰川服务价值评估及其时空特征 认领
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作者 孙美平 马维谦 +3 位作者 姚晓军 赵琳林 李忠勤 秦大河 《地理学报:英文版》 SCIE CSCD 2020年第8期1233-1248,共16页
Glaciers provide essential resources and services for human well-being and socio-economic development in arid regions.It is of great significance for regional socioeconomic sustainable development and environmental pr... Glaciers provide essential resources and services for human well-being and socio-economic development in arid regions.It is of great significance for regional socioeconomic sustainable development and environmental protection to conduct a glacier service value assessment and to analyze its spatiotemporal characteristics.Based on the first and second Chinese glacier inventories of the Qilian Mountains,a glacier service value evaluation system was established.Then the glacier service value and its spatiotemporal variation were assessed by combining the methods of unit area service price,value equivalent factor,and the glacier service value change index(GSCI).Three key results were obtained.(1)The total service value of glaciers in the Qilian Mountains for 2016 was 24.354 billion yuan.The main services provided were climate regulation and runoff regulation,which accounted for 60.58%and 33.14%of the total service value,respectively.Minor services were freshwater supply and hydropower,which accounted for 3.47%and 1.75%of the total value,respectively.The value of other types of services was about 0.259 billion yuan.(2)Among the various river systems in the Qilian Mountains,the Shule River basin had the highest glacier service value(7.771 billion yuan,31.91%),followed by the Haltang River basin(4.321 billion yuan,17.74%)and the Beida River basin(3.281 billion yuan,13.47%).In terms of administrative divisions,the glacier service value of the Qilian Mountains in Qinghai Province was 1.138 billion yuan higher than that of Gansu Province at 11.608 billion yuan,of which the services in the Haixi Mongol and Tibetan Autonomous Prefecture and Jiuquan City were valued at 11.124(45.68%)and 7.758(31.86%)billion yuan,respectively.(3)During the period from 1956 to 2010,the service value of glaciers in the Qilian Mountains declined by 435 million yuan,with an acceleration in the decreasing trend from west to east. 展开更多
关键词 GLACIER functions and services value evaluation spatiotemporal characteristics Qilian Mountains
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