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Spatio-temporal distribution of net primary productivity along the northeast China transect and its response to climatic change 被引量:9
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作者 朱文泉 潘耀忠 +1 位作者 刘鑫 王爱玲 《Journal of Forestry Research》 SCIE CAS CSCD 2006年第2期93-98,共6页
An improved Carnegie Ames Stanford Approach model (CASA model) was used to estimate the net primary productivity (NPP) of the Northeast China Transect (NECT) every month from 1982 to 2000. The spatial-temporal d... An improved Carnegie Ames Stanford Approach model (CASA model) was used to estimate the net primary productivity (NPP) of the Northeast China Transect (NECT) every month from 1982 to 2000. The spatial-temporal distribution of NPP along NECT and its response to climatic change were also analyzed. Results showed that the change tendency of NPP spatial distribution in NECT is quite similar to that of precipitation and their spatial correlation coefficient is up to 0.84 (P 〈 0.01). The inter-annual variation of NPP in NECT is mainly affected by the change of the aestival NPP every year, which accounts for 67.6% of the inter-annual increase in NPP and their spatial correlation coefficient is 0.95 (P 〈 0.01). The NPP in NECT is mainly cumulated between May and September, which accounts for 89.8% of the annual NPP. The NPP in summer (June to August) accounts for 65.9% of the annual NPP and is the lowest in winter. Recent climate changes have enhanced plant growth in NECT. The mean NPP increased 14.3% from 1980s to 1990s. The inter-annual linear trend of NPP is 4.6 gC·m^-2·a^-1, and the relative trend is 1.17%, which owns mainly to the increasing temperature. 展开更多
关键词 China Transect Remote sensing Net primary productivity (NPP) Climatic change spatio-temporal distribution
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Analysis on Spatio-temporal Distribution of Lightning in Dalian Area of China between 2007 and 2008 被引量:2
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作者 黄振 李万彪 《Meteorological and Environmental Research》 CAS 2010年第1期14-17,29,共5页
The cloud-to-ground lightning data between 2007 and 2008 were collected by lightning detection and location system,which was composed of four lightning detectors in four different sites of Dalian area.The spatio-tempo... The cloud-to-ground lightning data between 2007 and 2008 were collected by lightning detection and location system,which was composed of four lightning detectors in four different sites of Dalian area.The spatio-temporal distribution of cloud-to-ground lightning in surrounding areas of Dalian was analyzed from several aspects of polarity distribution,diurnal variation,lightning intensity and lightning density.The results showed that the number of negative lightning accounted for 93.9% of the total number of lightning,and its average lightning intensity was 27.99 kA.The number of positive lightning accounted for 6.1% of the total number of lightning,and its average lightning intensity was 35.56 kA.The diurnal variation of lightning frequency showed an obvious structure of two peaks (17:00-18:00 and 04:00-05:00) and two valleys (09:00-10:00 and 00:00-01:00).The number of lightning between May and September was 91.5% of the annual number,and the lightning occurred the most frequently between June and August.Most of positive and negative lightning was at the intensity of 15-35 kA,80.0% lower than 40 kA,and 99.3% lower than 100 kA.The lightning density had obvious regional differences in distribution,high in the Liaodong Bay and the Dalian Bay and low in inland areas.Therefore,coastal areas should attract more attention in lightning disaster defense in the surrounding areas of Dalian. 展开更多
关键词 Dalian area Lightning intensity spatio-temporal distribution China
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Epidemic Characteristics and Spatio-Temporal Patterns of HFRS in Qingdao City,China,2010-2022
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作者 Ying Li Runze Lu +8 位作者 Liyan Dong Litao Sun Zongyi Zhang Yating Zhao Qing Duan Lijie Zhang Fachun Jiang Jing Jia Huilai Ma 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2024年第9期1015-1029,共15页
Objective This study investigated the epidemic characteristics and spatio-temporal dynamics of hemorrhagic fever with renal syndrome(HFRS)in Qingdao City,China.Methods Information was collected on HFRS cases in Qingda... Objective This study investigated the epidemic characteristics and spatio-temporal dynamics of hemorrhagic fever with renal syndrome(HFRS)in Qingdao City,China.Methods Information was collected on HFRS cases in Qingdao City from 2010 to 2022.Descriptive epidemiologic,seasonal decomposition,spatial autocorrelation,and spatio-temporal cluster analyses were performed.Results A total of 2,220 patients with HFRS were reported over the study period,with an average annual incidence of 1.89/100,000 and a case fatality rate of 2.52%.The male:female ratio was 2.8:1.75.3%of patients were aged between 16 and 60 years old,75.3%of patients were farmers,and 11.6%had both“three red”and“three pain”symptoms.The HFRS epidemic showed two-peak seasonality:the primary fall-winter peak and the minor spring peak.The HFRS epidemic presented highly spatially heterogeneous,street/township-level hot spots that were mostly distributed in Huangdao,Pingdu,and Jiaozhou.The spatio-temporal cluster analysis revealed three cluster areas in Qingdao City that were located in the south of Huangdao District during the fall-winter peak.Conclusion The distribution of HFRS in Qingdao exhibited periodic,seasonal,and regional characteristics,with high spatial clustering heterogeneity.The typical symptoms of“three red”and“three pain”in patients with HFRS were not obvious. 展开更多
关键词 Hemorrhagic fever with renal syndrome Epidemic characteristics spatio-temporal distribution
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Integrated approach for understanding spatio-temporal changes in forest resource distribution in the central Himalaya
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作者 A K Joshi P K Joshi +1 位作者 T Chauhan Brijmohan Bairwa 《Journal of Forestry Research》 SCIE CAS CSCD 2014年第2期281-290,共10页
Intense anthropogenic exploitation has altered distribution of forest resources. This change was analyzed using visual interpretation of satellite data of 1979, 1999 and 2009. Field and interactive social surveys were... Intense anthropogenic exploitation has altered distribution of forest resources. This change was analyzed using visual interpretation of satellite data of 1979, 1999 and 2009. Field and interactive social surveys were conducted to identify spatial trends in forest degradation and data were mapped on forest cover and land use maps. Perceptions of villagers were compiled in a pictorial representation to understand changes in forest resource distribution in central Himalaya from 1970 to 2010. For- ested areas were subject to degradation and isolation due to loss of con- necting forest stands. Species like Lantana camara and Eupatorium adenophorum invaded forest landscapes. Intensity of human pressure differed by forest type and elevation. An integrated approach is needed to monitor forest resource distribution and disturbance. 展开更多
关键词 characterization FOREST central Himalaya integrated approach distribution spatio-temporal
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Implementing geostatistical analysis to study spatio-temporal distribution patterns of swimming crabs(Portunus trituberculatus)
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作者 Wenbin Zhu Kaner Lu +6 位作者 Zhanhui Lu Qian Dai Zhenghua Li Yongdong Zhou Siqi Huang Haichen Zhu Guocheng Cui 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2021年第6期67-74,共8页
This study attempted to compare the performance of local polynomial interpolation,inverse distance weighted interpolation,and ordinary kriging in studying distribution patterns of swimming crabs.Cross-validation was u... This study attempted to compare the performance of local polynomial interpolation,inverse distance weighted interpolation,and ordinary kriging in studying distribution patterns of swimming crabs.Cross-validation was used to select the optimum method to get distribution results,and kriging was used for making spatial variability analysis.Data were collected from 87 sampling stations in November of 2015(autumn)and February(winter),May(spring)and August(summer)of 2016.Results indicate that swimming crabs widely distributed in autumn and summer:in the summer,they were more spatially independent,and resources in each sampling station varied a lot;in the winter and spring,the abundance of crabs was much lower,but the individual crab size was bigger,and they showed the patchy and more concentrative distribution pattern,which means they were more spatially dependent.Distribution patterns were in accordance with ecological migration features of swimming crabs,which were affected by the changing marine environment.This study could infer that it is applicable to study crab fishery or even other crustacean species using geostatistical analysis.It not only helps practitioners have a better understanding of how swimming crabs migrate from season to season,but also assists researchers in carrying out a more comprehensive assessment of the fishery.Therefore,it may facilitate advancing the implementation in the pilot quota management program of swimming crabs in northern Zhejiang fishing grounds. 展开更多
关键词 swimming crabs(Portunus trituberculatus) geostatistical analysis ordinary kriging spatio-temporal distributions Zhejiang coastal waters of China
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Response of Spatio-temporal Distribution of Fishery Resources to Mairne Environment in the Northern South China Sea
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作者 Liu Zhunan Yu Jing 《Animal Husbandry and Feed Science》 CAS 2018年第5期311-317,320,共8页
[Objective] The paper was to investigate the spatio-temporal distribution of fishery resources in the northern South China Sea and to provide reference for scientific evaluation and effective protection of fishery res... [Objective] The paper was to investigate the spatio-temporal distribution of fishery resources in the northern South China Sea and to provide reference for scientific evaluation and effective protection of fishery resources in the northern South China Sea. [Methods] Based on monitoring data and satellite remote sensing data [including Sea Surface Temperature(SST), Chlorophyll a concentration(Chl a) and Sea Surface Wind(SSW)] in winter(January to February) and summer(August to September) in the northern South China Sea, the relationship between spatio-temporal distribution of fishery resources and marine environment was investigated by using Generalized Linear Models(GLM), fishing ground gravity and correlation analysis. [Results] The suitable SST and Chl a of light falling-net fishing ground in winter were 17-23°C and 0.2-0.6 mg/m3, respectively. The suitable SST and Chl a in summer were approximately 28°C and 0.2-1.0 mg/m3. Standardized Catch Per Unit Effort(SCPUE) was higher in summer(2-4) and lower in winter(1-3). From winter to summer, the fishing ground gravity migrated to the east about 1 °E. [Conclusion] The spatio-temporal distribution of fishery resources is related to eastern Hainan-western Guangdong upwelling and the coastal flow, caused by the monsoon in the northern South China Sea, and the major catch species of light falling-net. 展开更多
关键词 Fishing ground spatio-temporal distribution Marine environment Northern South China Sea
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Spatio-Temporal Distribution of Agricultural Non-Point Source Pollution in Binzhou City Based on Large Computer Data
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作者 Xiaodan FEI Kun RONG Yong LI 《Asian Agricultural Research》 2017年第3期61-63,共3页
Based on the relevant statistics on the agricultural non-point source pollution in Binzhou City,we studied the spatio-temporal variation in agricultural non-point source nitrogen pollution and phosphorus pollution in ... Based on the relevant statistics on the agricultural non-point source pollution in Binzhou City,we studied the spatio-temporal variation in agricultural non-point source nitrogen pollution and phosphorus pollution in Binzhou City during 2008-2015. The results showed that the agricultural non-point source nitrogen pollution and phosphorus pollution in Binzhou City changed from 114400 t and 28800 t in 2008 to110600 t and 24400 t in 2015,respectively; for the non-point source nitrogen pollution sources,the proportion of chemical fertilizer,manure and domestic sewage changed from 80. 41%,10. 47% and 9. 13% in 2008 to 82. 94%,4. 77% and 12. 29% in 2015,respectively; for the non-point source phosphorus pollution sources,the proportion of chemical fertilizer,manure and domestic sewage changed from 89. 29%,8. 32% and 2. 39% in 2008 to 91. 6%,4. 78% and 3. 62% in 2015,respectively; in 2015,the non-point source nitrogen pollution was most serious in Wudi County and Huimin County and least serious in Zhanhua County; the non-point source phosphorus pollution was most serious in Zouping County and least serious in Wudi County. 展开更多
关键词 Non-point source pollution NITROGEN PHOSPHORUS spatio-temporal distribution Binzhou City
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Distributed spatio-temporal generative adversarial networks
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作者 QIN Chao GAO Xiaoguang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2020年第3期578-592,共15页
Owing to the wide range of applications in various fields,generative models have become increasingly popular.However,they do not handle spatio-temporal features well.Inspired by the recent advances in these models,thi... Owing to the wide range of applications in various fields,generative models have become increasingly popular.However,they do not handle spatio-temporal features well.Inspired by the recent advances in these models,this paper designs a distributed spatio-temporal generative adversarial network(STGAN-D)that,given some initial data and random noise,generates a consecutive sequence of spatio-temporal samples which have a logical relationship.This paper builds a spatio-temporal discriminator to distinguish whether the samples generated by the generator meet the requirements for time and space coherence,and builds a controller for distributed training of the network gradient updated to separate the model training and parameter updating,to improve the network training rate.The model is trained on the skeletal dataset and the traffic dataset.In contrast to traditional generative adversarial networks(GANs),the proposed STGAN-D can generate logically coherent samples with the corresponding spatial and temporal features while avoiding mode collapse.In addition,this paper shows that the proposed model can generate different styles of spatio-temporal samples given different random noise inputs,and the controller can improve the network training rate.This model will extend the potential range of applications of GANs to areas such as traffic information simulation and multiagent adversarial simulation. 展开更多
关键词 distributed spatio-temporal generative adversarial network(STGAN-D) spatial discriminator temporal discriminator speed controller
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Spatial-temporal distribution of debris flow impact pressure on rigid barrier 被引量:7
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作者 LIU Dao-chuan YOU Yong +3 位作者 LIU Jin-feng LI Yong ZHANG Guang-ze WANG Dong 《Journal of Mountain Science》 SCIE CSCD 2019年第4期793-805,共13页
Grain composition plays a vital role in impact pressure of debris flow. Current approaches treat debris flow as uniform fluid and almost ignore its granular effects. A series of flume experiments have been carried out... Grain composition plays a vital role in impact pressure of debris flow. Current approaches treat debris flow as uniform fluid and almost ignore its granular effects. A series of flume experiments have been carried out to explore the granular influence on the impact process of debris flow by using a contact surface pressure gauge sensor(Tactilus~?, produced by Sensor Products LLC). It is found that the maximum impact pressure for debris flow of low density fluctuates drastically with a long duration time while the fluctuation for flow of high density is short in time, respectively presenting logarithmic and linear form in longitudinal attenuation. This can be ascribed to the turbulence effect in the former and grain collisions and grainfluid interaction in the latter. The horizontal distribution of the impact pressure can be considered as the equivalent distribution. For engineering purposes, the longitudinal distribution of the pressure can be generalized to a triangular distribution, from which a new impact method considering granular effects is proposed. 展开更多
关键词 DEBRIS flow Impact force GRAIN composition spatio-temporal distribution Dynamic coefficient
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Analysis of spatio-temporal changes in forest biomass in China
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作者 Weiyi Xu Xiaobin Jin +3 位作者 Jing Liu Xuhong Yang Jie Ren Yinkang Zhou 《Journal of Forestry Research》 SCIE CAS CSCD 2022年第1期261-278,共18页
Forests play a central role in the global carbon cycle.China's forests have a high carbon sequestration potential owing to their wide distribution,young age and relatively low carbon density.Forest biomass is an e... Forests play a central role in the global carbon cycle.China's forests have a high carbon sequestration potential owing to their wide distribution,young age and relatively low carbon density.Forest biomass is an essential variable for assessing carbon sequestration capacity,thus determining the spatio-temporal changes of forest biomass is critical to the national carbon budget and to contribute to sustainable forest management.Based on Chinese forest inventory data(1999–2013),this study explored spatial patterns of forest biomass at a grid resolution of 1 km by applying a downscaling method and further analyzed spatiotemporal changes of biomass at different spatial scales.The main findings are:(1)the regression relationship between forest biomass and the associated infuencing factors at a provincial scale can be applied to estimate biomass at a pixel scale by employing a downscaling method;(2)forest biomass had a distinct spatial pattern with the greatest biomass occurring in the major mountain ranges;(3)forest biomass changes had a notable spatial distribution pattern;increase(i.e.,carbon sinks)occurred in east and southeast China,decreases(i.e.,carbon sources)were observed in the northeast to southwest,with the largest biomass losses in the Hengduan Mountains,Southern Hainan and Northern Da Hinggan Mountains;and,(4)forest vegetation functioned as a carbon sink during 1999–2013 with a net increase in biomass of 3.71 Pg. 展开更多
关键词 Forest vegetation biomass Spatial distribution spatio-temporal changes
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Spatiotemporal Distribution of Cladocera and Rotifer of the Mangrove Waters of Mouanko (Coastal Cameroon): Influence of Some Abiotic Variables
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作者 Dongmo Rodrigue Nanfack Kueppo Eric Joselly Kouedeum +3 位作者 Gabriel Bertrand Zambo Georges Patrick Thiery Moanono Kayo Raoul Polycarpe Tuekam Togouet Serge Hubert Zébazé 《Open Journal of Ecology》 2022年第10期689-710,共22页
The Mouanko mangrove is subjected to major anthropogenic activities such as agriculture, fishing and deforestation, hence information on Cladocerans and Rotifers amongst other aquatic organisms in order to monitor and... The Mouanko mangrove is subjected to major anthropogenic activities such as agriculture, fishing and deforestation, hence information on Cladocerans and Rotifers amongst other aquatic organisms in order to monitor and manage this ecosystem is vital. The aim of this work is to study the physicochemical parameters of the environment that influence the diversity and spatiotemporal distribution of Cladocerans and Rotifers in the mangrove waters of Mouanko. This study was carried out from November 2019 to October 2020 at 8 sampling stations. Both biological and physico-chemical sampling and analyses were done following standard recommendations. The results of the phyico-chemical analyses revealed that the waters of the Mouanko mangroves were slightly basic (7.64 ± 0.71 UC), moderately oxygenated (69.56% ± 14.29%) with low levels of nutrients [ NO <sup>-</sup>2</sub> (0. 06 ± 0.05 mg/L), NH<sup>+</sup>4</sub> (0.39 ± 0.3 mg/L) and PO<sup>3-</sup>4</sub> (up to 0.12 mg/L)] and high values of electrical conductivity (up to 6531.04 μS/cm), salinity (up to 3.71‰). 15 species of Cladocerans and 30 species of Rotifers were identified accounting for a total abundance of 612 ind/L. The species richness was higher in freshwater influenced zones (40 taxa) compared to marinewater influenced zones (17 taxa). Among these species, the Cladocera, Penilia avirostris was the most abundant in marinewater influenced zones (84 ind/L) while the Rotifer, Keratella tecta was the most abundant in freshwater influenced zones (64 ind/L). Shannon-Weaver’s diversity and Pielou’s equitability indices indicated that freshwater influenced zones host a diverse community with a tendency towards equi-partition of species while marinewater influenced zones revealed the opposite. The low levels of organic pollution indicator variables recorded and the high diversity of the freshwater influenced zones population studied attested to the low level of anthropization in this environment. High salinity and electrical conductivity values influence the distribution of these organisms. 展开更多
关键词 CLADOCERA ROTIFERS spatio-temporal distribution Abiotic Variables Coastal Cameroon
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苏州艺圃游人观景视点时空分布规律研究
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作者 陈曦 肖湘东 +2 位作者 任严钊 谭立 钟誉嘉 《园林》 2024年第9期29-38,共10页
园林文化遗产是凝聚地方建造技艺与文化蕴涵的物质载体。以苏州古典园林艺圃为例,剖析古典园林景观形态特征作用于游人时空分布的内在机理。借助Python爬虫爬取网络用户生成内容(User Generated Content,UGC),根据UGC影像数据所反映的... 园林文化遗产是凝聚地方建造技艺与文化蕴涵的物质载体。以苏州古典园林艺圃为例,剖析古典园林景观形态特征作用于游人时空分布的内在机理。借助Python爬虫爬取网络用户生成内容(User Generated Content,UGC),根据UGC影像数据所反映的景观类型与观景视点进行信息提取与聚类分析。在此基础上,选取空间类型、景观偏好和季相表征为景观分析指标,将艺圃内各类景观形态特征与游人感知偏好指标间的相关性进行量化分析。初步结果表明,功能属性与空间类型、景观偏好类别、视线连通性、视域范围是影响游人空间分布的影响因子,植物季相特征构成了影响游人时空分布的主要因素。旨在科学量化游人观景视点的时空分布特征,深入解读游人的景观偏好及影响其观景行为时空分布的机制。 展开更多
关键词 艺圃 古典园林 用户生成内容 游人时空分布 景观偏好
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Analysis on characteristics of extreme precipitation indices and atmospheric circulation in Northern Shanxi
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作者 Xia Cai Yan Song +3 位作者 Lin Cai Xin Su GuiHua Liang YanMing Xu 《Research in Cold and Arid Regions》 CSCD 2024年第2期84-97,共14页
This article utilizes daily precipitation data from 28 national meteorological stations in northern Shanxi Province spanning from 1972 to 2020,and the US NCEP/NCAR monthly average reanalysis and ERA5 monthly average r... This article utilizes daily precipitation data from 28 national meteorological stations in northern Shanxi Province spanning from 1972 to 2020,and the US NCEP/NCAR monthly average reanalysis and ERA5 monthly average reanalysis data.The study employs techniques such as empirical orthogonal function(EOF)decomposition,MannKendall mutation and other methods to investigate the spatiotemporal distribution of extreme precipitation index in northern Shanxi and their correlation with atmospheric circulation.The research results show that:the absolute index,relative index,intensity index and sustained dry period index(CDD)in the continuous index appear from southwest to northeast.The spatial distribution characteristics of the central region decrease,while the continuous wet period(CWD)decreases from the central to the east and west.The three indices Rx1day,Rx5day,and CWD mutated in 1978,1975,and 1983 respectively,and other extreme precipitation indices all appeared in a sudden change from a low-value period to a high-value period occurred around 2010.In the high-value years of the summer extreme precipitation index,there is a significant negative anomaly in the height field in the mid-high latitude regions of Eurasia.Northern Shanxi is controlled by a broad low-pressure trough in the Lake Baikal area.Water vapor transported via the east,west,and south routes converges in the northern Shanxi region and encounters cold air from the north.There is a strong upward motion anomaly at 500 hPa in the troposphere,and the dynamic conditions of upper-level divergence and lower-level convergence lead to more summer extreme precipitation in the northern Shanxi region.Conversely,in the low-value years of the summer extreme precipitation index,northern Shanxi is affected by a strong high-pressure ridge north of Lake Baikal.There is a downward motion anomaly at 500 hPa,and the northern Shanxi region lacks water vapor.The cold and warm air cannot converge,and both the water vapor conditions and dynamic conditions are poor,which is not conducive to the production of extreme precipitation in northern Shanxi. 展开更多
关键词 Northern Shanxi Extreme precipitation indices spatio-temporal distribution and evolution MUTATIONS Atmospheric circulation anomaly
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Spatio-temporal distribution and transformation of cropland in geomorphologic regions of China during 1990–2015 被引量:10
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作者 GAO Xiaoyu CHENG Weiming +4 位作者 WANG Nan LIU Qiangyi MA Ting CHEN Yinjun ZHOU Chenghu 《Journal of Geographical Sciences》 SCIE CSCD 2019年第2期180-196,共17页
Landforms are an important factor determining the spatial pattern of cropland through allocation of surface water and heat. Therefore, it is of great importance to study the change in cropland distribution from the pe... Landforms are an important factor determining the spatial pattern of cropland through allocation of surface water and heat. Therefore, it is of great importance to study the change in cropland distribution from the perspective of geomorphologic divisions. Based on China's multi-year land cover data(1990, 1995, 2000, 2005, 2010 and 2015) and geomorphologic regionalization data, we analyzed the change in cropland area and its distribution pattern in six geomorphologic regions of China over the period of 1990-2015 with the aid of GIS techniques. Our results showed that the total cropland area increased from 177.1 to 178.5 million ha with an average increase rate of 0.03%. Cropland area decreased in southern China and increased in northern China. Region I(Eastern hilly plains) had the highest cropland increase rate, while the cropland dynamic degree of Region IV(Northwestern middle and high mountains, basins and plateaus) was significantly higher than that of other regions. The barycenter of China's cropland shifted from northern China to the northwest over the 25-year period. Regions IV and I were the two regions with the greatest increase of cropland. Region II(Southeastern low and middle mountains) and Region V(Southwestern middle and low mountains, plateaus and basins) were the main decreasing cropland regions. The area of cropland remained almost unchanged in Region III(Northern China and Inner Mongolia eastern-central mountains and plateaus) and Region VI(Tibetan Plateau). The loss of cropland occurred mostly in Regions I and II as a result of growing industrialization and urbanization, while the increase of cropland occurred mainly in Region IV because of reclamation of grassland and other wasteland. These analyzing results would provide fundamental information for further studies of urban planning, ecosystem management, and natural resourcesconservation in China. 展开更多
关键词 spatio-temporal distribution TRANSFORMATION of CROPLAND geomorphologic REGIONS China
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Spatio-temporal distribution of vascular plant species abundance on Qinghai-Tibet Plateau 被引量:5
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作者 FAN Zemeng BAI Ruyu YUE Tianxiang 《Journal of Geographical Sciences》 SCIE CSCD 2019年第10期1625-1636,共12页
For quantitatively explaining the correlations between the vascular plant species abundance (VPSA) and habitat factors, a spatial simulation method has been developed to simulate the distribution of VPSA on the Qingha... For quantitatively explaining the correlations between the vascular plant species abundance (VPSA) and habitat factors, a spatial simulation method has been developed to simulate the distribution of VPSA on the Qinghai-Tibet Plateau. In this paper, the vascular plant type, land cover, mean annual biotemperature, average total annual precipitation, topographic relief, patch connectivity and ecological diversity index were selected to screen the best correlation equation between the VPSA and habitat factors on the basis of 37 national nature reserves on the Qinghai-Tibet Plateau. The research results show that the coefficient of determination between VPSA and habitat factors is 0.94, and the mean error is 2.21 types per km<sup>2</sup>. The distribution of VPSA gradually decreases from southeast to northwest, and reduces with increasing altitude except the desert area of Qaidam Basin. Furthermore, the scenarios of VPSA on the Qinghai-Tibet Plateau during the periods from 1981 to 2010 (T0), from 2011 to 2040 (T2), from 2041 to 2070 (T3) and from 2071 to 2100 (T4) were simulated by combining the land cover change and the climatic scenarios of CMIP5 RCP2.6, RCP4.5 and RCP8.5. The simulated results show that the VPSA would generally decrease on the Qinghai-Tibet Plateau from T0 to T4. The VPSA has the largest change ratio under RCP8.5 scenario, and the smallest change ratio under RCP2.6 scenario. In general, the dynamic change of habitat factors would directly affect the spatial distribution of VPSA on the Qinghai- Tibet Plateau in the future. 展开更多
关键词 spatial simulation method VASCULAR plant species ABUNDANCE spatio-temporal distribution SCENARIO analysis Qinghai-Tibet PLATEAU
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Variation of spatio-temporal distribution of on-road vehicle emissions based on real-time RFID data 被引量:4
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作者 Yonghong Liu Wenfeng Huang +3 位作者 Xiaofang Lin Rui Xu Li Li Hui Ding 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2022年第6期151-162,共12页
High-resolution vehicular emissions inventories are important for managing vehicular pollution and improving urban air quality. This study developed a vehicular emission inventory with high spatio-temporal resolution ... High-resolution vehicular emissions inventories are important for managing vehicular pollution and improving urban air quality. This study developed a vehicular emission inventory with high spatio-temporal resolution in the main urban area of Chongqing, based on realtime traffic data from 820 RFID detectors covering 454 roads, and the differences in spatiotemporal emission characteristics between inner and outer districts were analysed. The result showed that the daily vehicular emission intensities of CO, hydrocarbons, PM2.5, PM10,and NO_(x) were 30.24, 3.83, 0.18, 0.20, and 8.65 kg/km per day, respectively, in the study area during 2018. The pollutants emission intensities in inner district were higher than those in outer district. Light passenger cars(LPCs) were the main contributors of all-day CO emissions in the inner and outer districts, from which the contributors of NO_(x) emissions were different. Diesel and natural gas buses were major contributors of daytime NO_(x) emissions in inner districts, accounting for 40.40%, but buses and heavy duty trucks(HDTs) were major contributors in outer districts. At nighttime, due to the lifting of truck restrictions and suspension of buses, HDTs become the main NO_(x) contributor in both inner and outer districts,and its three NO_(x) emission peak hours were found, which are different to the peak hours of total NO_(x) emission by all vehicles. Unlike most other cities, bridges and connecting channels are always emission hotspots due to long-time traffic congestion. This knowledge will help fully understand vehicular emissions characteristics and is useful for policymakers to design precise prevention and control measures. 展开更多
关键词 spatio-temporal distribution Link-level vehicular emission INVENTORY Real-time RFID data HDTs CHONGQING
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Spatio-temporal disparities of Clonorchis sinensis infection in animal hosts in China:a systematic review and meta-analysis
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作者 Kai Liu Jing Tan +5 位作者 Lu Xiao Rui‑Tai Pan Xiao‑Yan Yao Fu‑Yan Shi Shi‐Zhu Li Lan‐Hua Li 《Infectious Diseases of Poverty》 SCIE CAS CSCD 2023年第5期1-31,共31页
Background Clonorchis sinensis,one of the most important food-borne zoonotic trematodes,remains prevalent in China.Understanding its infection status in animals is crucial for controlling human clonorchiasis.Here we c... Background Clonorchis sinensis,one of the most important food-borne zoonotic trematodes,remains prevalent in China.Understanding its infection status in animals is crucial for controlling human clonorchiasis.Here we conducted a systematic review and meta-analysis to focus on the spatio-temporal disparities ofC.sinensis infection in animals in China.Methods Data onC.sinensis prevalence in snails,the second intermediate hosts,or animal reservoirs in China were extracted from electronic databases including PubMed,Embase,Web of Science,Chinese Wanfang database,CNKI,VIP,and China Biomedical Literature database.A random-effects meta-analysis model was utilized to estimate the pooled prevalence in each of the above animal hosts.Subgroup analysis and multivariable meta-regression were performed to explore potential sources of heterogeneity across studies and compare the temporal disparity of infection rates between high and low epidemic areas.Scatter plots were used to depict the biogeographical characteristics of regions reportingC.sinensis infection in animals.Results The overall pooled prevalence ofC.sinensis was 0.9%(95%CI:0.6-1.2%)in snails,14.2%(12.7-15.7%)in the second intermediate host,and 14.3%(11.4-17.6%)in animal reservoirs.Prevalence in low epidemic areas(with human prevalence<1%)decreased from 0.6%(0.2-1.2%)before 1990 to 0.0%(0.0-3.6%)after 2010 in snails(P=0.0499),from 20.3%(15.6-25.3%)to 8.8%(5.6-12.6%)in the second intermediate hosts(P=0.0002),and from 18.3%(12.7-24.7%)to 4.7%(1.0-10.4%)in animal reservoirs.However,no similar decrease in prevalence was observed in high epidemic areas(with human prevalence≥1.0%).C.sinensis infections were predominantly reported in areas with altitudes below 2346 m and annual cumulative precipitation above 345 mm and were mostly concentrated in eastern China.Conclusions There are spatio-temporal disparities in the animal infections ofC.sinensis in different areas of China.Animal infections are primarily concentrated in regions with low altitude and high precipitation.The results suggest that implementing One Health-based comprehensive measures targeting both humans and animals,especially in high epidemic areas,is essential for successful eradication ofC.sinensis in China. 展开更多
关键词 Clonorchis sinensis China PREVALENCE spatio-temporal distribution Biogeographical characteristics Animal host META-ANALYSIS
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北京市旅游客流时空分布特征与调控对策 被引量:96
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作者 牛亚菲 谢丽波 刘春凤 《地理研究》 CSCD 北大核心 2005年第2期283-292,共10页
在对北京市183个重要旅游景区进行了全面考查的基础上,分析北京市整体及中心城区、郊区客流时空变化特征,典型景区的客流变化规律与变化动因,以及客流在时间和空间分布上存在的不平衡现象和旅游产品的供给与需求之间错位问题。据此作者... 在对北京市183个重要旅游景区进行了全面考查的基础上,分析北京市整体及中心城区、郊区客流时空变化特征,典型景区的客流变化规律与变化动因,以及客流在时间和空间分布上存在的不平衡现象和旅游产品的供给与需求之间错位问题。据此作者提出进入产品衰落期的旅游产品淘汰的必然性;进入发展停滞阶段的旅游产品的振兴和复苏计划;旅游需求与供给的空间整合;价格杠杆的效用性和城区资源整合等观点。 展开更多
关键词 旅游客流 旅游产品 价格杠杆 旅游需求 供给与需求 效用性 北京 考查 不平衡现象 观点
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旅游网站访问者行为的时间分布及导引分析 被引量:111
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作者 路紫 赵亚红 +1 位作者 吴士锋 韩冰 《地理学报》 EI CSCD 北大核心 2007年第6期621-630,共10页
运用多种网上查询系统和网站访问量统计工具,获取了旅游网站访问者时间分布的较详细资料,基此总结了旅游网站访问者日内、周内、年内行为的时间分布特征,进而讨论了旅游网站访问者人数与景区旅游者人数之间的相关性及其信息流对人流的... 运用多种网上查询系统和网站访问量统计工具,获取了旅游网站访问者时间分布的较详细资料,基此总结了旅游网站访问者日内、周内、年内行为的时间分布特征,进而讨论了旅游网站访问者人数与景区旅游者人数之间的相关性及其信息流对人流的导引作用。研究发现:旅游网站访问者日内行为的基本规律是自身表现为一种双峰状态且国内北方显著于南方,其在使用时段上与整体互联网及其主要网站类型的“尖峰时段”特征有较大差异,日内旅游网站访问者人数与景区旅游者人数时间分布的基本一致性说明信息流对人流不具导引作用;旅游网站访问者周内行为的基本规律是自身呈现出周末较少平日较多的特征,与整体互联网及与互联网其他类型的网站比较既有相同性也有差异性,旅游网站平日访问量较高周末访问量较低的特征与周内旅游人数平日较少周末较多的“Z”型分布呈互补状;旅游网站访问者年内行为的基本规律是依据旅游网站的地域性明显与否而形成国内南北方的多种类型,其访问者的时间行为与旅游者人数波动的紧密关系是由自然季节因素的,旅游地旅游网站年内访问者人数走势与该旅游地旅游者人数走势表现出的波涟状特征可解释为信息流对人流发生导引作用。 展开更多
关键词 旅游网站 访问者行为 时间分布特征 信息流 人流 导引
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基于GIS的上海世博会游人分布和流动预测分析 被引量:2
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作者 葛振鸣 周晓 +2 位作者 王小明 王开运 王天厚 《城市环境与城市生态》 CAS CSCD 2006年第6期26-28,共3页
2010年上海世博会将在黄浦江两岸举办,通过对展期间游人集中分布的分析可知,世博园浦东会场的中国馆及邻近的水上出入口、主题馆和浦西会场的企业馆区域游人可能最为密集,而部分交通节点附近和浦东西部区域游人相对分散。通过展期内游... 2010年上海世博会将在黄浦江两岸举办,通过对展期间游人集中分布的分析可知,世博园浦东会场的中国馆及邻近的水上出入口、主题馆和浦西会场的企业馆区域游人可能最为密集,而部分交通节点附近和浦东西部区域游人相对分散。通过展期内游客流动模式的预测可知,整个世博园区是以浦东中部的中国馆和邻近的外国馆、主题馆、公共活动中心,浦东西部的外国馆区,以及浦西的企业馆区域游人活动频率最高,中国馆区域的过江人流频度较高,而各场馆以及游人密集区通向交通节点的人流相对平缓。基于以上GIS空间分析,提出了如何控制局部地区游人数量和安全有效地疏散游人的场地规划建议。 展开更多
关键词 上海世博会 游人分布 流动模式 GIS
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