检索结果-南通市图书馆

Some characteristics of the atmosphere during an adiabatic process

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第6期16卷 644-648页

作者： GAO Li, LI Jianping and REN Hongli (LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china Graduate School of Chinese Academy of Sciences, beijing 100049, china national Climate center, Laboratory of Climate Studies, china Meteorological Administration, beijing 100081, china) [a]LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China [b]Graduate School of Chinese Academy of Sciences Beijing China [c]national Climate center Laboratory of Climatic Studies China Meterological Administration Beijing China

Some important characteristics of the atmosphere during an adiabatic process are investigated, which include the invariability of atmospheric entropy range and local surface potential temperature, the conservation of the atmospheric mass intervened between any isentropic surface and the ground, and the isentropic surface intersecting with the ground. The analysis shows that the atmospheric reference state (ARS) for investigation on available potential energy (APE) should be defined objectively as the state which could be approached from the existing atmosphere by adiabatic adjustment, and be related to initial atmospheric state before adjustment. For the initial atmosphere state at any time, its corresponding ARS is different from the one at another time. Based on the above-mentioned conclusions, the reference state proposed by Lorenz cannot be obtained physically, so a new conception, the conditional minimum total potential energy, is put forward in order to objectively investigate atmospheric APE.

关键词： available potential energy adiabatic isentropic surface atmospheric reference state conditional minimum total potential energy.

Three-dimensional decomposition method of global atmospheric circulation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china Earth Sciences 2008年第3期51卷 386-402页

作者： LIU HaiTao1,2,3, HU ShuJuan4, XU Ming5 & CHOU JiFan6,7 1 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china 2 Graduate University of Chinese Academy of Sciences, beijing 100049, china 3 beijing Climate center, beijing 100089, china 4 Department of Mathematics, Lanzhou University, Lanzhou 730000, china 5 Shanghai Typhoon Institute, Shanghai 200030, china 6 Department of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, china 7 china Meteorological Administration Training center, beijing 100089, china 1. State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 2. Graduate University of Chinese Academy of Sciences Beijing 100049 China 3. beijing Climate center Beijing 100089 China 4. Department of Mathematics Lanzhou University Lanzhou 730000 China 5. Shanghai Typhoon Institute Shanghai 200030 China 6. Department of Atmospheric Sciences Lanzhou University Lanzhou 730000 China 7. china Meteorological Administration Training center Beijing 100089 China

By adopting the idea of three-dimensional Walker, Hadley and Rossby stream functions, the global atmospheric circulation can be considered as the sum of three stream functions from a global perspective. Therefore, a m... 详细信息

关键词： three-dimensional decomposition of the global atmospheric circulation generalized Walker Hadley and Rossby stream functions existence and uniqueness vertical motion

Frontal genesis of moisture atmosphere during the early 2008 persistent freezing-rain event in southern 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3期53卷 454-464页

作者： QIAN WeiHong1 & FU JiaoLan1,2 1 Department of Atmospheric Sciences, School of Physics, Peking University, beijing 100871, china 2 national Meteorological center of CMA, beijing, 100081, china 1. Department of Atmospheric Sciences School of Physics Peking University Beijing 100871 China2. National Meteorological Center of CMA Beijing 100081 China

From January 10 to February 2, 2008, a severe and persistent freezing-rain event occurred in southern and southwestern china. Here we use an observational analysis to compare the persistent freezing-rain event in the early 2008 with the winter precipita- tion in the late 2007 over south of the Yangtze River (Jiangnan). The persistent freezing-rain event was directly linked to the activity of quasi-stationary front. The gradient of equivalent temperature (ET) can well indicate the frontal genesis of moist atmosphere (moisture front) and its activity as well as its relationship with precipitation belt. The precipitation types (snow and freezing rains) are related to the vertical structure of moisture front. The inversion profile of ET vertical distribution is a typical synoptic condition that caused the freezing-rain event. The horizontal gradient of ET with a criterion of 10℃ / 100 km, which reflects the accumulation and release of atmospheric energy, can be applied to predict the precipitation 5-10 days in advance.

关键词： freezing-rain event frontal genesis extended-range weather forecast winter Jiangnan

Method for tumor recognition with short dynamic PET images:Theory and simulation study

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2009年第1期19卷 73-77页

作者： Huiting Qiao a,Jing Bai a,Yingmao Chen b,Jiahe Tianb a Department of Biomedical Engineering,School of Medicine,tsinghua University,beijing 100084,china b Department of Nuclear Medicine,General Hospital of PLA,beijing 100853,china [a]Department of Biomedical Engineering School of Medicine Tsinghua University Beijing 100084 China [b]Department of Nuclear Medicine General Hospital of PLA Beijing 100853 China

A new method was provided in this paper to recognize tumor in PET images automatically and reduce the waiting time of *** on the unsupervised clustering algorithm(ISODATA),this method diagnoses tumor with short dynamic PET *** theoretical basis of this method is that the metabolic characteristics of different tissues,represented by time-activity curve in the region of interest,are *** computer program was developed and validated using simulated dynamic PET data with small tumor in *** study shows that this method could recognize tumor with the short dynamic PET data in 10 min successfully,and this method was not sensitive to initial cluster center.

关键词： Dynamic PET Clustering algorithm Tumor recognition Simulation

In flight MTF monitoring and compensation for CCD camera on CBERS-02

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2005年第S2期48卷 29-43页

作者： GU Xingfa1,2,3, LI Xiaoying1,2,4, MIN Xiangjun5, YU Tao1,2, SUN Jijuan5, ZENG Yong1,2,4, XU Hua1,2 & GUO Ding2,6 1. State Key Laboratory of Remote Sensing Science, Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and beijing Normal University, beijing 100101, china 2. The center for national Spaceborne Demonstration, beijing 100101, china 3. Institut national de la Recherche Agronomique, Climat Sol Environnement, 84914 Avignon, France 4. Graduate University of Chinese Academy of Sciences, beijing 100039, china 5. china center for Resource Satellite Data and Application, beijing 100830, china 6. University of electronic Science and Technology of china, Chengdu 610054, china State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University 100101 Beijing China The center for national Spaceborne Demonstration 100101 Beijing China Institut national de la Recherche Agronomique Climat Sol Environnement 84914 Avignon France Graduate University of Chinese Academy of Sciences 100039 Beijing China china center for Resource Satellite Data and Application 100830 Beijing China University of electronic Science and Technology of china 610054 Chengdu China

In this article, the approach of simulating ideal tarp scene was proposed to determine the MTF for CCD camera on CBERS-02. The MTF acquired from this technique was compared to those from some common methods. MTFs achieved from different approaches were employed to compensate the CCD images based on three restoration algorithms: the iterative method, the Wiener filter and the modified inverse filter (MIF). The two-dimensional MTF was established with the value at frequency 0.5 for 45° directional MTF as the value at its four corners. This article addressed the variations of the restored CCD images with different techniques of constructing two-dimensional MTF, restoring algorithms and determining the in-flight MTFs. Results showed images restored with the MTF determined from the technique of simulating ideal tarp scene represent the real scene best. And the restoration technique based on the MIF would produce better restored images than the other two techniques. This research also demonstrated that the two-dimensional MTF used for restoration should be interpolated under the control of the MTF for 45° axis, rather than by multiplying the cross-orbit MTF with along-orbit MTF.

关键词： CBERS-02 CCD MTF the technique of simulating ideal tarp scene.

Modification of LiCo_(1/3)Ni_(1/3)Mn_(1/3)O_2 cathode material by CeO_2-coating

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2009年第9期52卷 2737-2741页

作者： WANG Meng,WU Feng,SU YueFeng & CHEN Shi beijing Key Laboratory of Environment,School of Chemical Engineering and Environment,beijing Institute of Technology national Development center of High Technology Green Materials,beijing 100081,china beijing Key Laboratory of Environment School of Chemical Engineering and Environment Beijing Institute of Technology Beijing China national Development center of High Technology Green Materials Beijing 100081 China

LiCo1/3Ni1/3Mn1/3O2 was coated by a layer of 1.0 wt% CeO2 via sol-gel method. The bared and coated LiMn1/3Co1/3Ni1/3O2 was characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),cyclic voltammogram (CV) and galvanotactic charge-discharge test. The results show that the coating layer has no effect on the crystal structure,only coating on the surface; the 1.0 wt% CeO2-coated LiCo1/3Ni1/3Mn1/3O2 exhibits better discharge capacity and cycling performance than the bared LiCo1/3Ni1/3Mn1/3O2. The discharge capacity of 1.0 wt% CeO2-coated cathode is 182.5 mAh.g-1 at a current density of 20 mA.g-1,in contrast to 165.8 mAh.g-1of the bared sample. The discharge capacity retention of 1.0 wt% CeO2-coated sample after 12 cycles reaches 93.2%,in comparison with 86.6% of the bared sample. CV results show that the CeO2 coating could suppress phase transitions and prevent the surface of cathode material from direct contact with the electrolyte,thus enhance the electro-chemical performance of the coated material.

关键词： LiCo1/3Ni1/3Mn1/3O2 CeO2 coating Lithium-ion battery

(0,1, …, m - 2, m) INTERPOLATION FOR THE LAGUERREABSCISSAS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1994年第3期12卷 123-131页

作者： Shi Ying-guang (Computing center, Academia Sinica, beijing, china) CHINESE ACAD SCI CTR COMPBEIJINGPEOPLES R CHINA

A necessary and sufficient condition of regularity of (0,1,…, m - 2, m) interpo-lation on the zeros of the Laguerre polynomials Ln(α) (x) (α≥ -1) in a manageable form is established. Meanwhile, the explicit representation of the fundamental polynomials, when they exist, is given. Moreover, it is shown that, if the problem of (0,1,…, m - 2, TO) interpolation has an infinity of solutions, then the general form of the solutions is f0(x) + Cf1(x) with an arbitrary constant C.

关键词： INTERPOLATION FOR THE LAGUERREABSCISSAS

同方期刊数据库

An integrated view of the correlations between genomic and phenomic variables

在线全文

学校读者我要写书评

暂无评论

Journal of Genetics and Genomics 2009年第11期36卷 645-651页

作者： Dong Yang,Ying Jiang,Fuchu He State Key Laboratory of Proteomics,beijing Proteome Research center,beijing Institute of Radiation Medicine,beijing 102206,china [a]State Key Laboratory of Proteomics Beijing Proteome Research Center Beijing Institute of Radiation Medicine Beijing 102206 China

Genome sequencing opened the flood gate of ＂-omics＂ studies, among which the research about correlations between genomic and phenomic variables is an important part. With the development of functional genomics and systems biology, genome-wide investigation of the correlations between many genomic and phenomic variables became possible. In this review, five genomic variables, such as evolution rate （or ＂age＂ of the gene）, the length of intron and ORF （protein length） in one gene, the biases of amino acid composition and codon usage, along with the phenomic variables related to expression patterns （level and breadth） are focused on. In most cases, genes with higher mRNA/protein expression level tend to evolve slowly, have less intronic DNA, code for smaller proteins, and have higher biases of amino acid composition and codon usage. In addition, broadly expressed proteins evolve more slowly and are shorter than tissue-specific proteins. Studies in this field are helpful for deeper understanding the signatures of selection mediated by the features of gene expression and are of great significance to enrich the evolution theory.

关键词： genomic variable phenomic variable expression pattern evolution selection

Redevelopment of liftoff rates of saltating sand grains based on a simple optimization model

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2010年第4期53卷 568-574页

作者： CHENG Hong & ZOU XueYong State Key Laboratory of Earth Surface Processes and Resource Ecology,beijing Normal University,beijing 100875,china MOE Engineering center of Desertification and Blown-sand Control,beijing Normal University,beijing 100875,china Key Laboratory of Environmental Change and Natural Disaster of the Ministry of Education of china,beijing Normal University,beijing 100875,china 1. State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Beijing 100875 China2. MOE Engineering Center of Desertification and Blown-sand Control Beijing Normal University Beijing 100875 China3. Key Laboratory of Environmental Change and Natural Disaster of the Ministry of Education of China Beijing Normal University Beijing 100875 China

This paper is a redevelopment result of liftoff rates of saltating sand grains based on our previous *** sand flow is a complex multi-phase flow because of a special two-phase gas-solid flow near ground *** extensive research on the movement of blowing sand,no model fully characterizes aeolian sand flow,and large differences often exist between simulations of aeolian sand movement and field *** key problem is a few of sufficient research on liftoff rates of saltating sand grains(also called the number of liftoff sand grains per unit time and per unit bed area).It is necessary to re-search in advance liftoff rates of saltating sand *** redeveloped liftoff rates of saltating sand grains by establishing an optimization model based on the flux of aeolian sand flow at different heights of the sampler in wind tunnel and the simulated capture of saltating sand grains by different heights of the sampler that are from different liftoff position(distance from the sampler) in order to revise previous inversion condition of liftoff rates of saltating sand *** rates increased rapidly with increasing wind *** frictional wind velocities of u=0.67,0.77,0.82,0.83,and 0.87 m s-1,liftoff rates were 3840,954502,523.114,5499407,and 7696291 sand grain s-1 m-2,*** rates could be expressed as the square of the instantaneous frictional wind velocity and a constant(0.663) that differs from the critical(threshold) frictional wind velocity at which saltation *** our results require additional experimental validation and the simple optimization model must be improved,they nonetheless provide a strong basis for future research.

关键词： liftoff rates of saltating sand grains optimization model wind tunnel two-phase gas-solid flow