检索结果-南通市图书馆

Tracking the evolution processes and behaviors of mesoscale eddies in the South China Sea：a global nearest neighbor filter approach

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2017年第11期36卷 27-37页

作者： YI Jiawei DU Yunyan WANG Dongxiao zhou chenghu State Key Laboratory of Resources and Environmental Information System Institute of Geographic Science and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China State Key Laboratory of Tropical Oceanography (LTO) South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China

The eddy tracking approach is developed using the global nearest neighbor filter（GNNF） to investigate the evolution processes and behaviors of mesoscale eddies in the South China Sea（SCS）. Combining the Kalman filter and optimal data association technologies, the GNNF algorithm is able to reduce pairing errors to 0.2% in tracking synthetic eddy tracks, outperforming other existing methods. A total of 4 913 eddy tracks that last more than a week are obtained by the GNNF during 1993–2012. The analysis of a growth and a decay based on 3 445 simple eddy tracks show that eddy radius, amplitude, and vorticity smoothly increase during the first half of lifetime and decline during the second half following a parabola opening downwards. The genesis of eddies mainly clusters northwest and southwest of Luzon Island whereas the dissipations concentrate the Xisha Islands where the underwater bay traps and terminates eddies. West of the Luzon Strait, northwest of Luzon Island, and southeast of Vietnam are regions where eddy splits and mergers are frequently observed. Short disappearances mainly distribute in the first two regions. Moreover, eddy splits generally result in a decrease of the radius and the amplitude whereas eddy mergers induce growing up. Eddy intensity and vorticity, on the contrary, are strengthened in the eddy splits and diminished in mergers.

关键词： mesoscale ocean eddies eddy tracking eddy split eddy merger South China Sea

Spatio-temporal evolution and influencing factors of urban green development efficiency in China

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2020年第5期30卷 724-742页

作者： zhou Liang zhou chenghu CHE Lei WANG Bao Faculty of Geomatics Lanzhou Jiaotong UniversityLanzhou 730070China State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China School of Architecture and Urban Planning Nanjing UniversityNanjing 210093China Northwest Institute of Eco-Environment and Resources CASLanzhou 730000China

To resolve conflicts between development and the preservation of the natural environment,enable economic transformation,and achieve the global sustainable development goals(SDGs),green development(GD)is gradually becoming a major strategy in the construction of an ecological civilization and the ideal of building a"beautiful China",alongside the transformation and reconstruction of the global *** on a combination of the concept and implications of GD,we first used the Slacks Based Model with undesirable outputs(SBM-Undesirable),the Theil index,and the spatial Markov chain to measure the spatial patterns,regional differences,and spatio-temporal evolution of urban green development efficiency(UGDE)in China from 2005 to ***,by coupling natural and human factors,the mechanism influencing UGDE was quantitatively investigated under the framework of the human-environment *** results showed that:(1)from 2005 to 2015,the UGDE increased from 0.475 to 0.523,i.e.,an overall increase of 10%.In terms of temporal variation,there was a staged increase,with its evolution having the characteristics of a"W-shaped"pattern.(2)The regional differences in UGDE followed a pattern of eastern>central>*** different types of urban agglomeration,the UGDE had inverted pyramid cluster growth characteristics that followed a pattern of"national level>regional level>local level",forming a stable hierarchical scale structure of"super cities>mega cities>big cities>medium cities>small cities".(3)UGDE in China has developed with significant spatial agglomeration ***-efficiency type cities have positive spillover effects,while low-efficiency cities have negative *** types of urban evolution processes have a path dependence,and a spatial club convergence phenomenon exists,in which areas with high UGDE are concentrated and drive low UGDE elsewhere.(4)Under the framework of regional human-environment interaction,the degree of human and soc

关键词： green development efficiency green city green economy spatial scale sustainable development goals(SDGs)

Enhanced piecewise regression based on deterministic annealing

在线全文

学校读者我要写书评

暂无评论

Science in China(Series F) 2008年第8期51卷 1025-1038页

作者： ZHANG JiangShe YANG YuQian CHEN XiaoWen zhou chenghu Institute for Information and System Sciences Faculty of Sciences Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Resources & Environmental Information System Institute of Geography Chinese Academy of Sciences Beijing 100101 China

Regression is one of the important problems in statistical learning theory. This paper proves the global convergence of the piecewise regression algorithm based on deterministic annealing and continuity of global minimum of free energy w.r.t temperature, and derives a new simplified formula to compute the initial critical temperature. A new enhanced plecewise regression algorithm by using ＂migration of prototypes＂ is proposed to eliminate ＂empty cell＂ in the annealing process. Numerical experiments on several benchmark datasets show that the new algorithm can remove redundancy and improve generalization of the piecewise regression model.

关键词： statistical regression piecewise regression deterministic annealing generalization

Climate effects on an inland alpine lake in Xinjiang, China over the past 40 years

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2013年第2期5卷 188-198页

作者： HuiXia CHAI WeiMing CHENG chenghu zhou ShangMin ZHAO HaiJiang LIU State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Department of Surveying Mapping College of Mining Technology Taiyuan University of Technology China National Environmental Monitoring Center

Inland lakes are important water resources in arid and semiarid regions. Understanding climate effects on these lakes is critical to accurately evaluate the dynamic changes of water resources. This study focused on the changes in Sayram Lake of Xinjiang, China, and addressed the effects of climate fluctuations on the inland lake based on long-term sequenced remote sensing images and meteorological data from the past 40 years. A geo- graphic information system （GIS） method was used to obtain the hypsometry of the basin area of Sayram Lake, and estimation methods for evaporation from rising temperature and water levels from increasing precipitation were proposed. Results showed that：（1）Areal values of Sayram Lake have increased over the past 40 years. （2） Both temperature and precipitation have increased with average increases of more than 1.8~C and 82 mm, respectively. Variation of the water levels in the lake was consistent with local climate changes, and the areal values show linear relationships with local temperature and precipitation data. （3） According to the hypsometry data of the basin area, the estimated lake water levels increased by 2.8 m, and the water volume increased by 12.9×108 m3 over the past 40 years. The increasing area of Sayram Lake correlated with local and regional climatic changes because it is hardly affected by human activities.

关键词： Sayram Lake climate change water body extraction areal variation inland alpine lake

Numerical modeling and prediction of future response of permafrost to different climate change scenarios on the Qinghai-Tibet Plateau

在线全文

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2016年第5期9卷 442-456页

作者： Wenjie Zhang zhoupeng Ren Ling Yao chenghu zhou Yunqiang Zhu State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application NanjingChina

Projecting the future distribution of permafrost under different climate change scenarios is essential,especially for the Qinghai–Tibet Plateau(QTP).The altitude-response model is used to estimate future permafrost changes on the QTP for the four RCPs(RCP2.6,RCP4.5,RCP6.0,and RCP8.5).The simulation results show the following:(1)from now until 2070,the permafrost will experience different degrees of significant degradation under the four RCP *** will affect 25.68%,40.54%,45.95%,and 62.84%of the current permafrost area,respectively.(2)The permafrost changes occur at different rates during the periods 2030–2050 and 2050–2070 for the four different RCPs.(1)In RCP2.6,the permafrost area decreases a little during the period 2030–2050 but shows a small increase from 2050 to 2070.(2)In RCP4.5,the rate of permafrost loss during the period 2030–2050(about 12.73%)is higher than between 2050 and 2070(about 8.33%).(3)In RCP6.0,the permafrost loss rate for the period 2030–2050(about 16.52%)is similar to that for 2050–2070(about 16.67%).(4)In RCP8.5,there is a significant discrepancy in the rate of permafrost decrease for the periods 2030–2050 and 2050–2070:the rate is only about 3.70%for the first period but about 29.49%during the second.

关键词： future permafrost changes Qinghai-Tibet Plateau altitude-response model temperature data VLRT RCPs

Oceanographic ontology-based spatial knowledge query

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2005年第4期24卷 66-71页

作者： WANG Jinggui SU Fenzhen zhou chenghu DU Yunyan YANG Xiaomei State Key Laboratory of Resources and Environmental Information Systems Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Institute of Sciences Research Zhujiang River Water Resources Commission Ministry of Water Resources Guangzhou 510611 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China

The construction of oceanographic ontologies is fundamental to the ＂digital ocean＂. Therefore, on the basis of introduction of new concept of oceanographic ontology, an oceanographic ontology-based spatial knowledge query （OOBSKQ） method was proposed and developed. Because the method uses a natural language to describe query conditions and the query result is highly integrated knowledge, it can provide users with direct answers while hiding the complicated computation and reasoning processes, and achieves intelligent, automatic oceanographic spatial information query on the level of knowledge and semantics. A case study of resource and environmental application in bay has shown the implementation process of the method and its feasibility and usefulness.

关键词： spatial information query oceanographic ontology MGIS

Scale effects of the continental coastline of China

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2011年第6期21卷 1101-1111页

作者： SU Fenzhen GAO Yi zhou chenghu YANG Xiaomei FEI Xianyun LREIS Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China Yantai Institute of Coastal Zone Research CAS Yantai 264003 Shandong China Graduate University of Chinese Academy of Sciences Beijing 100049 China School of Geodesy ＆ Geomatics Engineering Huaihai Institute of Technology Lianyungang 222005Jiangsu China Jiangsu Marine Resources Development Research Institute Lianyungang 222005 Jiangsu China

Spatial scale is a fundamental problem in Geography. Scale effect caused by fractal characteristic of coastline becomes a common focus of coastal zone managers and researchers. In this study, based on DEM and remote sensing images, multi-scale continental coastlines of China were extracted and the fractal characteristic was analyzed. The results are shown as follows. （1） The continental coastline of China fits the fractal model, and the fractal dimension is 1.195. （2） The scale significant differences according to uplift effects with fractal dimensions of coastline have and subsidence segments along the continental coastlines of China. （3） The fractal dimension of coastline has significant spatial heterogeneity according to the coastline types. The fractal dimension of sandy coastline located in Luanhe River plain is 1.109. The dimension of muddy coastline located in northern Jiangsu Plain is 1.059, while that of rocky coastline along southeastern Fujian is 1.293. （4） The length of rocky coastline is affected by scale more than that of muddy and sandy coastline. Since coastline is the conjunction of sea, land and air surface, the study of coastline scale effect is one of the scientific bases for the researches on air-sea-land interaction in multi-scales.

关键词： scale effect fractal dimension coastline uplift segment subsidence segment coastline type

Spatio-temporal rupture process of the 2008 great Wenchuan earthquake

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2009年第2期52卷 145-154页

作者： ZHANG Yong FENG WanPeng XU LiSheng zhou chenghu CHEN YunTai School of Earth and Space Sciences Peking UniversityBeijing 100871China Institute of Geophysics China Earthquake AdministrationBeijing 100081China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China

Focal mechanism and dynamic rupture process of the Wenchaun Ms8.0 earthquake in Sichuan province on 12 May 2008 were obtained by inverting long period seismic data from the Global Seismic Network (GSN), and characteristics of the co-seismic displacement field near the fault were quantitatively ana-lyzed based on the inverted results to investigate the mechanism causing disaster. A finite fault model with given focal mechanism and vertical components of the long period P-waves from 21 stations with evenly azimuthal coverage were adopted in the inversion. From the inverted results as well as after-shock distribution, the causative fault of the great Wenchuan earthquake was confirmed to be a fault of strike 225°/dip 39°/rake 120°, indicating that the earthquake was mainly a thrust event with right-lateral strike-slip component. The released scalar seismic moment was estimated to be about 9.4×1020―2.0×1021 Nm, yielding moment magnitude of Mw7.9―8.1. The great Wenchuan earthquake occurred on a fault more than 300 km long, and had a complicated rupture process of about 90 s duration time. The slip distribution was highly inhomogeneous with the average slip of about 2.4 m. Four slip-patches broke the ground surface. Two of them were underneath the regions of Wenchuan-Yingxiu and Beichuan, respectively, with the first being around the hypocenter (rupture initiation point), where the largest slip was about 7.3 m, and the second being underneath Beichuan and extending to Pingwu, where the largest slip was about 5.6 m. The other two slip-patches had smaller sizes, one having the maximum slip of 1.8 m and lying underneath the north of Kangding, and the other having the maximum slip of 0.7 m and lying underneath the northeast of Qingchuan. Average and maximum stress drops over the whole fault plane were estimated to be 18 MPa and 53 MPa, respectively. In addition, the co-seismic displacement field near the fault was analyzed. The results indicate that the features of the co-seis

关键词： Wenchuan earthquake earthquake rupture process co-seismic displacement

The International Workshop on Flood Damage Evaluation Information System and Wetland Use Held in Changsha

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 1992年第1期 114-115页

作者： zhou chenghu

The International Workshop on Flood Damage Evaluation Information System and Wetland Use,co-sponsored by the National Remote Sensing Centre(NRSC),the National Lab of Resources and Environment Information System,and Changsha Branch of NRSC,was held in Changsha,the capital city of Hunan Province from September *** than 45 experts and scientists from Canada,the Netherland,Czechoslovakia,Bangladesh,Pakistan,Thailand,Indonesia,

关键词： Flood In The International Workshop on Flood Damage Evaluation Information System and Wetland Use Held in Changsha Lake GIS