检索结果-南通市图书馆

Some thermodynamic criteria for river channel changes

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 1998年第4期8卷 21-29页

作者： WANG Zheng institute of policy & {2., chinese academy of Sciences, beijing 100080, china

A theoretical model of river channel changes is presented, which shows some nonequilibrium thermodynamic criteria of a river channel to bedding and equilibrium.

关键词： river channel changes one-dimensional ideal river geographical system.

Optimization of mathematical models for thematic maps

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第S1期53卷 15-24页

作者： QI QingWen1,ZHANG An1,JIANG LiLi1,ZOU XiuPing2.XU Li3 & CHENG Xi1,4 1 institute of Geographical Sciences and Natural Resources Research,chinese {2. of Sciences,beijing 100101,china 2.institute of policy and management,chinese {2. of Sciences,beijing 100080,china 3 Taishan University,Taian 2.102.,china 4 Graduate University of chinese {2. of Sciences,beijing 100049,china institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China institute of policy and {2. Chinese Academy of Sciences Beijing China Taishan University Taian China Graduate University of chinese academy of Sciences Beijing China

The thematic map is a major class of maps designed to demonstrate particular features or concepts,functioning as an indispensable tool in geographical *** process of thematic mapping is one into which geographical research goes deeply and *** key activity and course of thematic map production is the use of mathematical models to create thematic data ***,the selection and optimization of mathematical models is in the forefront of thematic map *** theoretical foundations,mechanisms and methods of mathematical model optimization are expounded in this paper,including two approaches,the phase by phase mode and the multi-aim scheme balance *** studies in eco-environment mapping and emergency mapping are described and analyzed,with a hierarchical analysis method being used in the model optimization for eco-environment fragility and sensitivity assessment mapping in Beibuwan (Guangxi) District,the dynamic system (DS) method being used in the model optimization for ecological security adjustment mapping in Xishuang Banna,Yunnan province,and the multi-phase mode being used in the models for forest fire and infectious diseases mapping.

关键词： thematic map mathematic model optimization

Spatial interaction: a statistical mechanism model

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2000年第3期10卷 87-92页

作者： WANG Zheng (institute of policy and {2., chinese academy of Sciences, beijing 100080, china) 中科院政策与管理所北京 100080

In this paper some micro-mechanisms of spatial interaction is discussed with a view of statistical physics. The paper found the relation between spatial interaction and geographical diffusion, and some new conclusions... 详细信息

关键词： spatial interaction population diffusion

Potential land for plantation of Jatropha curcas as feedstocks for biodiesel in china

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2010年第1期53卷 120-127页

作者： WU WeiGuang 1,2.3,HUANG JiKun 1,3 & DENG XiangZheng 1,3 1 institute of Geographic Sciences and Natural Resources Research,chinese {2. of Sciences,beijing 100101,china 2.Department of Economics and management,Zhejiang Forestry University,Linan 311300,china 3 Center for chinese Agricultural policy,chinese {2. of Sciences,beijing 100101,china institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Department of Economics and management Zhejiang Forestry University Linan China Center for chinese Agricultural policy Chinese Academy of Sciences Beijing China

As a renewable energy,biofuel has attracted great attention in china and the rest of *** with the national food security,china recently has shifted its biofuel development priority from grain-based to non-grain-based biofuels,including forest-based biodiesel,since *** curcas is one of major biodiesel ***,there is rising debate on availability of land for expanding Jatropha curcas *** overall goal of this paper is to evaluate potential land for Jatropha curcas used as feedstock for biodiesel in *** on remote sensing data on land use,data on meteorological,soil and land slope,and suitable environment for Jatropha curcas plantation,this study uses Agro Ecological Zone method and considers social-economic constraints to evaluate potential suitable land for Jatropha curcas plantation in china's major Jatropha curcas production region,Southwest *** results show that while there are some potential lands to expand Jatropha curcas areas,amount of these lands will hardly meet the government's target for Jatropha curcas-based biodiesels development in the *** may need to reconsider its long-term targets on the development of Jatropha curcas-based biodiesels.

关键词： biodiesel Jatropha curcas potential land suitability evaluation Southwest china

Design of secure operating systems with high security levels

在线全文

学校读者我要写书评

暂无评论

Science in china(Series F) 2007年第3期50卷 399-418页

作者： QING SiHan1,2.& SHEN ChangXiang3 1 institute of Software, chinese {2. of Sciences, beijing 100080, china 2.School of Software and Microelectronics, Peking University, beijing 102.00, china 3 institute of Computing Technology, Navy, beijing 100841, china institute of Software Chinese Academy of Sciences Beijing China School of Software and Microelectronics Peking University Beijing China institute of Computing Technology Navy Beijing China

Numerous Internet security incidents have shown that support from secure operating systems is paramount to fighting threats posed by modern computing environments. Based on the requirements of the relevant national and international standards and criteria, in combination with our experience in the design and development of the ANSHENG v4.0 secure operating system with high security level （hereafter simply referred to as ANSHENG OS）, this paper addresses the following key issues in the design of secure operating systems with high security levels： security architecture, security policy models, and covert channel analysis. The design principles of security architecture and three basic security models： confidentiality, integrity, and privilege control models are discussed, respectively. Three novel security models and new security architecture are proposed. The prominent features of these proposals, as well as their applications to the ANSHENG OS, are elaborated. Cover channel analysis （CCA） is a well-known hard problem in the design of secure operating systems with high security levels since to date it lacks a sound theoretical basis and systematic analysis approach. In order to resolve the fundamental difficulties of CCA, we have set up a sound theoretical basis for completeness of covert channel identification and have proposed a unified framework for covert channel identification and an efficient backward tracking search method. The successful application of our new proposals to the ANSHENG OS has shown that it can help ease and speedup the entire CCA process.

关键词： secure operating systems with high security levels architecture security model covert channel analysis

Fundamental study of CO_2.control technologies and policies in china

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2008年第7期51卷 857-870页

作者： JIN HongGuang1, ZHANG XiLiang2. GAO Lin1, YUE Li2. HE JianKun2.& CAI RuiXian1 1 institute of Engineering Thermophysics, chinese {2. of Sciences, beijing 100080, china 2.institute of Nuclear and New Energy Technology, Tsinghua University, beijing 100084, china institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China institute of Nuclear and New Energy Technology Tsinghua University Beijing China

The technical roadmap and policies for CO2.mitigation suitable for china are a common center of attention in the fields of energy, environment, and management science in the country. Emphasizing interaction between technical research and {2. research, this work discovers the potential breakthrough in the integrated field. The technical difficulties of recovering CO2.are pointed out, the mechanism of combining CO2.recovery with energy conversion is investigated, and the basic principle for integrating an environmental-friendly energy system is discussed. Moreover, the formulation of a new energy system that can recover CO2.with very low or even zero energy penalty is proposed, while the assessment methodology and model system for the technical roadmap of CO2.emission control are developed. Finally, a new technical roadmap constructing an energy network suitable for china is proposed, which may provide a new way for the development of sustainable energy and environment technologies.

关键词： CO2 capture and storage technical roadmap energy policy

Regional differences and determinants of built-up area expansion in china

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2007年第12期50卷 1835-1843页

作者： HUANG JiKun1,2.ZHU LiFen3,1 & DENG XiangZheng1,2.1 Center for chinese Agricultural policy,chinese academy of Sciences,beijing 100101,china 2.institute of Geographic Sciences and Natural Resources Research,chinese academy of Sciences,beijing 100101,china 3 Research Center of the Economy of the Upper Reaches of the Yangtze River,Chongqing Technology and Business University,Chongqing 400067,china Center for chinese Agricultural policy Chinese Academy of Sciences Beijing China institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Research Center of the Economy of the Upper Reaches of the Yangtze River Chongqing Technology and Business University Chongqing China

Based on remote sensing data on land use provided by the chinese academy of Sciences and socio-economic data collected by the authors,this paper analyzes the trends and regional differences in built-up area(BUA) expansion in {2. from the late 1980s to 2.00,and empirically estimates the major determinants of BUA expansion in different regions in 1996―*** 1989―2.00,although {2.'s overall BUA expansion accelerated,the trends differed significantly among *** expansion in the central and western regions accelerated significantly,but it slowed down considerably in the east-ern *** estimation results from our econometric analysis reveal that BUA expansion in the eastern region reached a period when economic growth had no further significant impact on per capita BUA,the land utilization in this region has become more intensive with further expansion of the *** the central and western regions,the BUA has expanded remarkably due to the relatively more flexible land development policies and the relatively cheap land ***,as the econ-omy continues to grow rapidly,policies relating to BUA expansion and cultivated land reductions may face more serious challenges in the central and western regions.

关键词： built-up area, land use, regional difference, determinants, china

Carrying Capacity:An Overview

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Population,Resources and Environment 2004年第1期2卷 35-40页

作者： Chen Shaofenginstitute of policy and {2. Science, CAS, beijing 100080, china institute of policy and {2. Science CAS BJ 100080 China

The concept of carrying capacity is derived from ecology, with widespread contentions of its theoretical connotations and applications in the international academic community, especially the impact of human activities on the environment. Disputes on carrying capacity have been occurring not only among biologists and ecologists, but also among mainstream economists. Based on their efforts, the author makes an attempt to describe its origin, connotations, problems, measurement, and at the same time note the latest international progress in this field.

关键词： Carrying Capacity Sustainable Development

Impacts of the Wenchuan Earthquake on the Giant Panda Nature Reserves in china

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2010年第2期7卷 197-206页

作者： DENG Xiangzheng JIANG Qunou GE Quansheng YANG LinSheng institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Center for chinese Agricultural policy Chinese Academy of Sciences Beijing 100101 China Graduate University of the chineseacademy of Sciences Beijing 100049 China

The Wenchuan Earthquake that occurred in May of 2.08 caused damages to large areas of Sichuan,Gansu,and Shaanxi provinces in *** from local governments and related management agencies show that the giant panda nature reserves in the earthquake-hit areas were heavily *** estimates in this paper of the impacts of the earthquake on the giant panda in the earthquake-hit areas were made based on the interpretation of remote sensing images and information collected by field survey.A rapid assessment method was designed to estimate the damages of the earthquake on giant panda *** using visual interpretation methods,we decoded the remote sensing images of the disaster area in the 49 giant panda nature *** results showed that the Wenchuan Earthquake and the succeeding secondary geological disasters caused great damages to the giant panda nature reserves and disturbed the normal life of the giant pandas there (e.g.,landscape fragmentation increased significantly).Undoubtedly,the life of the giant pandas there was ***,although the earthquake caused certain impacts on the giant pandas,it did not really threat their *** so,we still strongly advocate for protection of the giant pandas,and have prioritized a couple of measures to be taken to restore the giant panda nature reserves in the earthquake-hit areas.

关键词： Wenchuan earthquake Remote sensing Giant panda Giant panda nature reserve Rapid assessment method