检索结果-南通市图书馆

Prediction method for October 2.03 solar storm

在线全文

学校读者我要写书评

暂无评论

Science china(Technological sciences) 2006年第5期49卷 629-640页

作者： XIE Yanqiong1, 2. 3, WEI Fengsi1, FENG Xueshang1 & ZHONG Dingkun1, 2.1. State key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of sciences, {2. 100080, china 2. Graduate school, Chinese Academy of sciences, {2. 100039, china 3. Institute of Meteorology, PLA university of Science and Technology, Nanjing 2.1101, china State key Laboratory of Space Weather Center for Space Science Applied Research Chinese Academy of Sciences Beijing 100080 China Graduate school Chinese Academy of Sciences Beijing 100039 China Institute of Meteorology PLA University of Science Technology Nanjing 211101 China

Aiming at two intense shock events on October 2. and 2., 2.03, this paper presents a two-step method, which combines synoptic analysis of space weather ——“observing” and quantitative prediction ——“palpating”, and then uses it to test predictions. In the first step of “observing”, on the basis of observations of the solar source surface magnetic field, interplanetary scintillation (IPS) and ACE spacecraft, we find that the propagation of the shocks is asymmetric relative to the normal direction of their solar sources, and the Earth is located near the direction of the fastest speed and the greatest energy of the shocks. As the two fast ejection shock events, the fast explosion of coronal mass of the extremely high temperature, the strong magnetic field, and the high speed background solar wind are also helpful to their rapid propagation. In the second step of “palpating”, we adopt a new membership function of the fast shock events for the ISF method. The predicted results show that for the onset time of the geomagnetic disturbance, the relative errors between the observational and the predicted results are 1.8% and 6.7%; and for the magnetic disturbance magnitude, the relative errors are 4.1% and 3.1%, re- spectively. Furthermore, the comparison among the predicted results of our two-step method with those of five other prevailing methods shows that the two-step method is advantageous. The results tell us that understanding the physical features of shock propagation thoroughly is of great importance in improving the prediction precision.

关键词： solar storm, interplanetary shock, interplanetary scintillation, two-step method, ISF method.

Scale effects of leaf area index inversion based on environmental and disaster monitoring satellite data

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2010年第S1期53卷 92-98页

作者： ZHANG Hao1,LI XiaoWen1,2.CAO ChunXiang1,YANG Hua2.GAO MengXu1,3,ZHENG Sheng1,3,XU Min1,3,XIE DongHui2.JIA HuiCong1,JI Wei1,ZHAO Jian1,3,CHEN Wei1,3 & NI XiLiang1,3 1 State key Laboratory of Remote Sensing Science,Jointly Sponsored by Institute of Remote Sensing Applications,Chinese Academy of sciences and{2.,beijing 100101,china 2.State key Laboratory of Remote Sensing Science,Jointly Sponsored by{2. and Institute of Remote Sensing Applications of Chinese Academy of sciences,beijing 100875,china 3 Graduate university of Chinese Academy of sciences,beijing 100049,china 1. State key Laboratory of Remote Sensing Science Jointly Sponsored by Institute of Remote Sensing Applications Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China2. State Key Laboratory of Remote Sensing Science Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing Applications of Chinese Academy of Sciences Beijing 100875 China3. Graduate University of Chinese Academy of Sciences Beijing 100049 China

The spatial distribution of sub-pixel components has an impact on retrieval accuracy,and should be accounted for when inverting a three-dimensional adiative transfer model to retrieve leaf area index(LAI).To investigate this effect,we constructed three realistic scenarios with the same LAI values and other properties,except that the simulated plants had different *** implemented the radiosity method to subsequently produce synthetic bidirectional reflectance factor(BRF) datasets based upon these simulated *** inversion was conducted using these data,which showed that spatial distribution affects retrieval *** inversion was also conducted for LAI based on charge-coupled device(CCD) data from the environment and Disaster Monitor Satellite(HJ-1),which depicted both forest and drought-resistant crop land *** showed that heterogeneity in coarse-resolution remote sensing data is the main error source in LAI *** spatial distribution of global fractal dimension index,which can be used to describe the area of sub-pixel components and their spatial distribution modes,shows good consistency with the coarse resolution LAI inversion error.

关键词： HJ-1 leaf area index scale effect spatial distribution

A study on determining the location of groundwater divide using a mathematical morphology method

在线全文

学校读者我要写书评

暂无评论

Science china(Technological sciences) 2006年第z2期49卷 141-148页

作者： PAN Yun, GONG Huili, DUAN Fuzhou & HU Zhuowei key Laboratory of 3D Information Acquisition and Application, ministry of {2., Capital normal university, beijing 100037, china key Laboratory of Resource environment and GIS of beijing, Capital normal university, beijing 100037, china Capital normal Univ Minist Educ Key Lab D Informat Acquisit & Applicat 3 Beijing 100037 Peoples R China Capital normal Univ Key Lab Resource Environm Beijing 100037 Peoples R China Capital normal Univ GIS Beijing Beijing 100037 Peoples R China

Placement of a groundwater divide indicates sink areas and spatial distribution, knowledge of which helps in the mapping of regional aquifer properties and the management of groundwater resources. By applying mathematical morphology to a conceptual model of a watershed and characteristic erosion and dilation operations, this paper proposes a structuring element with which to extract the shape and location of groundwater divide. With due consideration to watershed linearity, a structuring element with three origins is designed to connect watershed points. After erosion, closing, and dilation operations, the groundwater divide is determined; the results indicate this method's feasibility and accuracy.

关键词： groundwater divide, mathematical morphology, structuring element.

A technique on automatic land-use database reconstruction based on scanning land-use map

在线全文

学校读者我要写书评

暂无评论

Science china(Technological sciences) 2006年第z2期49卷 57-63页

作者： LI Xiaojuan, GONG Huili, YIN Lianwang, SUN Yonghua, YANG Lingli & WANG Yanggang key Laboratory of 3D Information Acquisition and Application, ministry of {2., Capital normal university, beijing 100037, china key Laboratory of Resource environment and GIS of beijing, Capital normal university, beijing 100037, china Capital normal Univ Minist Educ Key Lab D Informat Acquisit & Applicat 3 Beijing 100037 Peoples R China Capital normal Univ Key Lab Resource Environm Beijing 100037 Peoples R China Capital normal Univ GIS Beijing Beijing 100037 Peoples R China

Although a land-cover database is very important to national land use including urban planning and land-use management, it is very laborious and time-consuming to build through digitization of paper land-use maps (1:10000) and data input by hand. Here we propose a new, high-level, automatic technique to build a land-use database, which has proved useful and practical in building a land-use database of Baotou City.

关键词： land-use map vectonzation automatic building of land-use database.

Approximation of functions on the Sobolev space with a Gaussian measure

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2010年第2期53卷 373-384页

作者： WANG HePing 1, ZHANG YanWei 2.& ZHAI XueBo 1 1 school of Mathematical sciences, Capital {2. university, beijing 100048, china 2.Department of Mathematics, Zaozhuang university, Zaozhuang 2.7160, china 1. school of Mathematical sciences Capital Normal University Beijing 100048 China2. Department of Mathematics Zaozhuang University Zaozhuang 277160 China

We discuss the best approximation of periodic functions by trigonometric polynomials and the approximation by Fourier partial summation operators, Valle-Poussin operators, Ces`aro operators, Abel opera-tors, and Jackson operators, respectively, on the Sobolev space with a Gaussian measure and obtain the average error estimations. We show that, in the average case setting, the trigonometric polynomial subspaces are the asymptotically optimal subspaces in the L q space for 1≤q < ∞, and the Fourier partial summation operators and the Valle-Poussin operators are the asymptotically optimal linear operators and are as good as optimal nonlinear operators in the L q space for 1≤q < ∞.

关键词： average width best approximation approximation by linear operators Sobolev space Gaussian measure

^(137)Cs tracing of lacustrine sediments in the Dalian Lake,Qinghai Province,china

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第S1期46卷 83-87页

作者： VAN Ping, DONG Guangrong & DONG Zhibaochina Certer of Desert Research at beijing normal university, {2.100875, china:key Laboratory of environmental Change and Natural Disaster, the ministry of education of china, beijing normal university, beijing 100875, china Cold and Arid Regions environmental and Engineering Research Institute, Chinese Academy of sciences, Lanzhou 730000, china 1. china Certer of Desert Research at beijing normal university 100875 Beijing China 2. key Laboratory of environmental Change and Natural Disaster The Ministry of Education of China Beijing Normal University 100875 Beijing China 3. Cold and Arid Regions environmental and Engineering Research Institute Chinese Academy of Sciences 730000 Lanzhou China

Based upon the analysis of Cs and grain-size parameters, the total amounts of 137Cs deposition by wind and water in the Dalian Lake of Gonghe Basin, Qinghai Province are defined. The vertical profile of 137Cs in the lacustrine sediments exhibits three 137Cs activity maxima and one minimum. The major maximum corresponds to the global I37Cs fallout in 1963; the two secondary maxima correspond to the leakage of the Chernobyl reactor in 1986 and complete desiccation of the lake in 1994, respectively. The minimum corresponds to aeolian deposition caused by extensive reclamation in the late 1980s and early 1990s. The 137Cs data set was used to evaluate average sedimentation rate of the Dalian Lake since 1963. The deposition was stable in 1963-1986 and 1994-1998, and it was rapid during 1986?994. This preliminary study reveals that l37Cs has the same potential to trace environmental changes introduce by human interference in arid/semiarid regions as in humid regions.

关键词： 137Cs technique Dalian Lake sedimentation rate.

Subchronic toxicological effects of aquatic nitrobenzene on Medaka and Chinese rare minnow

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2007年第5期50卷 707-717页

作者： ZHOU QunFang1, FU JianJie1,2. MENG HaiZhen1,2. ZHU XueYan1,2. JIANG GuiBin1, ZHANG JianBin1, LIU JieMin2.& SHI GuoQing2.1 State key Laboratory of environmental Chemistry and Ecotoxicology, Research Center for Eco-environmental sciences, Chinese Academy of sciences, beijing 100085, china 2.Department of Chemistry, school of Applied Science, university of Science and Technology beijing, beijing 100083, china State key Laboratory of environmental Chemistry and Ecotoxicology ResearchCenter for Eco-environmental SciencesChinese Academy of SciencesBeijing 100085China Department ofChemistry School of Applied ScienceUniversity of Science and Technology B

Based on the simulative exposure experiments of nitrobenzene to two small experimental fishes, Medaka (Oryzias latipes) and Chinese Rare Minnow (Gobiocypris rarus), it was found that nitrobenzene could decrease in a linear way in the static aquatic system. Both fishes could accumulate dose-related levels of nitrobenzene quickly and eliminate the compound rapidly when they were transferred to clean water. The Chinese rare minnow showed more sensitivity to the acute toxicity exposure of nitrobenzene than Medaka. Typical molecular biomarkers in oxidative defense system including superoxide dismu- tase (SOD), catalase (CAT) showed the chemical induced alterations. The changes of acetylcholi- nesterase (AChE) activities indicated that nitrobenzene might affect the normal neural function. Nitro- benzene exposure could also lead to obvious damaging effects on the target organs, such as gill and liver by hitopathological studies.

关键词： nitrobenzene, Medaka, Chinese rare minnow, bioaccumulation, elimination, molecular biomarkers, histopathological effects

CONCURRENT SORPTION OF HEAVY METAL POLLUTANTS OF sediment OF DIFFERENT GRAIN SIZES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1997年第2期9卷 1-12页

作者： Huang Sui-liangState key Joint Laboratory of environmental Simulation and Pollution Control, Laboratoryof {2. environment Simulation,beijing normal university, beijing 100875, P. R. chinaWan Zhao-huichina Institute of {2. Conservancy and Hydroelectric beijing normal Univ Beijing China

Generally, sediment in natural rivers is non-uniform, and sorption capacities of different grain sizes vary greatly. In order to quantitatively describe sorption of heavy metal pollutant by sediment in natural rivers, the concurrent sorption by sediment of different grain sizes should be studied. By combining systematic laboratory experiments and theoretical analysis the concurrent equilibrium sorption model and the concurrent sorption dynamic model by sediment of different grain sizes have been set up. Both of them indicate that there is no competition or interference among different grain sizes, its sorption content of unit weight of sediment is the sum of the sorption contents of each grain sizes , and the content of each grain size in non-uniform sediment. Furthermore, formulas for determining characteristic parameters ( b and k) in the Langmuir sorption isotherm for non-uniform sediment are deduced as follows:These can be used as a tool for predicting the sorption content of non-uniform sediment in natural rivers.

关键词： sediment concurrent sorption model grain sizes

Entropy product measure for multipartite pure states

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 606-615页

作者： CAO Wancang1,2. LIU Dan2. PAN Feng3 & LONG Guilu2.4 1. Department of Physics, Chifeng College, Chifeng 02.001, china 2. key Laboratory for Quantum Information and Measurements, Department of Physics, Tsinghua {2., beijing 100084, china 3. Department of Physics, Liaoning normal {2., Dalian 11602., china 4. key Laboratory for Atomic and Molecular Nano-sciences, Tsinghua {2., beijing 100084, china Correspondence should be addressed to Long Guilu Department of Physics Chifeng College Chifeng 024001 China key Laboratory for Quantum Information Measurements Department of Physics Tsinghua University Beijing 100084 China Department of Physics Liaoning Normal University Dalian 116029 China key Laboratory for Atomic Molecular Nano-sciences Tsinghua University Beijing 100084 China

An entanglement measure for multipartite pure states is formulated using the product of the von Neumann entropy of the reduced density matrices of the constituents. Based on this new measure, all possible ways of the maximal entanglement of the triqubit pure states are studied in detail and all types of the maximal entanglement have been compared with the result of ‘the average entropy’. The new measure can be used to calculate the degree of entanglement, and an improvement is given in the area near the zero entropy.

关键词： multipartite pure state von Neumann entropy entanglement measure