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Principle and application of three-band gradient difference vegetation index

Science china Earth Sciences 2005年第2期48卷 241-249页

作者： TANG Shihao, ZHU Qijiang, WANG Jindi, ZHOU Yuyu & ZHAO Feng Research center for Remote Sensing and GIS, Department of Geography, beijing Normal University, beijing 100875, china national Satellite Meteorological center, china Meteorological Administration, beijing 100081, china 1. Research center for Remote Sensing and GIS Department of Geography Beijing Normal University 100875 Beijing China 2. national Satellite Meteorological center China Meteorological Administration 100081 Beijing China

Vegetation index is a simple, effective and experiential measurement of terrestrial vegetation activity, and plays a very important role in qualitative and quantitative remote sensing. Aiming at shortages of current vegetation indices, and starting from the analysis of vegetation spectral characteristics, we put forward a new vegetation index, the three-band gradient difference vegetation index (TGDVI), and established algorithms to inverse crown cover fraction and leaf area index (LAI) from it. Theoretical analysis and model simulation show that TGDVI has high saturation point and the ability to remove the influence of background to some degree, and the explicit functional relation with crown cover fraction and LAI can be established. Moreover, study shows that TGDVI also has the ability to partly remove the influence of thin cloud. Experiment in the Shunyi District, beijing, china shows that reasonable result can be reached using the vegetation index to retrieve LAI. We also theoretically analyzed the reason why the normalized difference vegetation index (NDVI) owns the low saturation point, and show that it is determined by the definition of NDVI and the characteristic of vegetation spectra, and is unavoidable to some degree. Meanwhile, through model simulation, we also indicate that the relationship between simple ratio vegetation index (SR) and LAI closes to a piecewise linear one instead of a linear one, which is mainly caused by the influence of background and different change rates of reflectance in red and infrared bands with LAI increasing.

关键词： vegetation index, remote sensing, LAI, crown cover fraction, remote sensing inversion.

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Isospin-dependent relativistic microscopic optical potential in the Dirac Brueckner-Hartree-Fock method

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Science china(Physics,Mechanics & Astronomy) 2004年第2期47卷 189-198页

作者： RONG Jian1 & MA Zhongyu1,2,3 1. china Institute of Atomic Energy, beijing 102413, china 2. center of Nuclear Theoretical Physics, national Laboratory of Heavy Ion Accelerator of Lanzhou, Lan-zhou 730000, china 3. Institute of Theoretical Physics, Chinese Academy of Sciences, beijing 100080, china Correspondence should be addressed to Rong Jian (email: jrong@***) 1. china Institute of Atomic Energy 102413 Beijing China 2. center of Nuclear Theoretical Physics National Laboratory of Heavy Ion Accelerator of Lanzhou 730000 Lanzhou China 3. Institute of Theoretical Physics Chinese Academy of Sciences 100080 Beijing China

The relativistic microscopic optical potential in the asymmetric nuclear matter is studied in the framework of the Dirac Brueckner-Hartree-Fock method. A new decomposition of the Dirac structure of the nuclear self-energy in nuclear matter is adopted. The self-energy of a nucleon with E > 0 in nuclear matter is calculated with the G matrix in the Hartree-Fock approach. The optical potential of a nucleon in the nuclear medium is identified with the nucleon self-energy. The energy and asymmetric parameter dependence of the relativistic optical potentials for proton and neutron are discussed. The resulting Schroedinger equivalent potentials have reasonable behaviors of the energy dependence. The asymmetric parameter dependence of relativistic optical potentials and Schroedinger potentials are emphasized.

关键词： Dirac Brueckner Hartree-Fock, relativistic microscopic optical potential, asymmetric nuclear matter, isospin-dependence.

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Simulation of 1991-2005 Meiyu seasons in the Yangtze-Huaihe region using BCC_RegCM 1.0

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Chinese Science Bulletin 2010年第11期55卷 1077-1083页

作者： HU YaMin1,2,3& DING YiHui4 1 Institute of Tropical and Marine Meteorology, china Meteorological Administration, Guangzhou 510080, china 2 Guangdong Climate center, Guangzhou 510080, china 3 Chinese Academy of Meteorological Sciences, beijing 100081, china 4 national Climate center, china Meteorological Administration, beijing 100081, china Institute of Tropical and Marine Meteorology China Meteorological Administration Guangzhou 510080 China Guangdong Climate center Guangzhou 510080 China Chinese Academy of Meteorological Sciences Beijing 100081 China national Climate center China Meteorological Administration Beijing 100081 China

By using BCC_RegCM 1.0 (RegCM for short) from beijing Climate center (BCC), china Meteorological Administration (CMA), the Meiyu season characters over the Yangtze-Huaihe region during 1991-2005 are simulated. The major conclusions of this study may be summarized as the following: (1) RegCM can reproduce the interannual variation and the spatial distribution of the summertime precipitation and temperature in the Yangtze-Huaihe region. (2) By use of a generalized Meiyu criterion and in accordance with model-calculated precipitation and temperature, the Meiyu onset and ending date have been determined. Compared with the observation, RegCM can simulate the interannual variation of the Yangtze-Huaihe Meiyu with preferable capability for most of the normal Meiyu years (such as 1995, 1997, 2000, 2001, 2002 and 2004), especially for the rich Meiyu years of 1996, 1998 and 1999. (3) In terms of the average simulation for the recent 15 years, the timings of onset and ending of Meiyu occur on June 1 and July 13, respectively, which are earlier than the climatological observation. For duration, Meiyu persists for 32 d, 3 d shorter than the observation. The index of Meiyu intensity is 2.45, while the climatological one is 3.00. Therefore, RegCM is capable of simulating the climatological Meiyu duration and intensity, while the capability of simulating the onset and ending date of Meiyu still needs to be improved.

关键词：梅雨季节模拟计算长江气候观测发病时间强度指数中国气象局空间分布

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CHEMICAL STRUCTURE DEPENDENCE OF THE INTERNAL ENERGY CONTRIBUTION IN RUBBER ELASTICITY

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Chinese Journal of Polymer Science 2001年第5期19卷 447-449页

作者： Juan Sun Xiao-zhen Yang Polymer Physics Laboratory center for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences beijing 100080 china Chinese Acad Sci Polymer Phys Lab Ctr Mol Sci Inst Chem Beijing 100080 Peoples R China

Conformational elasticity theory recently developed has been used to explore the internal energy contribution to the elastic force f(e)/f as a function of strain for poly(cis-1,4-isoprene) and poly(trans-1,4-isoprene). Calculated f(e)/f values are in good agreement with those obtained experimentally. Results show that behavior of f(e)/f is mainly contributed by chemical structure, or intramolecular interaction, supporting the experimental observations, and that the internal energy contribution is strain dependent.

关键词： conformational elasticity theory internal energy contribution poly(cis-1,4-isoprene) poly(trans-1,4-isoprene)

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Astronomical function and date of the Taosi observatory

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Science china(Physics,Mechanics & Astronomy) 2009年第1期52卷 151-158页

作者： WU JiaBi1, CHEN MeiDong2 & LIU CiYuan3 1 national Astronomical Observatories, Chinese Academy of Sciences, beijing 100012, china 2 Institute for the History of Natural Science, Chinese Academy of Sciences, beijing 100010, china 3 national Time Service center, Chinese Academy of Sciences, Xi’an 710600, china 1. national Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China 2. Institute for the History of Natural Science Chinese Academy of Sciences Beijing 100010 China 3. national Time Service center Chinese Academy of Sciences Xi’an 710600 China

The Taosi site in Xiangfen County,Shanxi Province,may be the capital of the King Yao. Archeologists recently discovered a large semi-circular stamped-earth platform, II FJT1,which has a clear and definite pounded-earth central core together with a curved wall perforated by twelve gaps. The platform is said to be an ancient observatory used to determine the seasons by watching the sunrise. Each feature of II FJT1 was precisely measured and the data are reproduced in this paper. An astronomical analysis of slots E2 and E12 was carried out using the azimuths of the slots' centerlines and the vertical angle of the mountain ridge opposite, above which the sun rises. The results show that at present the sun is close to the two slots but does not exactly enter them at summer and winter solstice sunrise. Using 14C analysis archeologists dated the site to about 2100 BC. Because of the secular change in the obliquity of the ecliptic,at that date on the summer solstice the half-risen sun would have appeared inside slot E12 just to the right of the centerline,and on the winter solstice the sun would have been exactly on the centerline of slot E2. This result provides compelling proof that II FJT1 is an ancient observatory.

关键词： astro-archeology astro-chronology Taosi culture ancient observatory time service

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Vortex genesis over the Bay of Bengal in spring and its role in the onset of the Asian Summer Monsoon

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Science china Earth Sciences 2011年第1期54卷 1-9页

作者： WU GuoXiong1, GUAN Yue1,2, WANG TongMei3, LIU YiMin1, YAN JingHui4 & MAO JiangYu1 1 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china 2Graduate University of Chinese Academy of Sciences, beijing 100049, china 3Department of Atmospheric Science, Sun Yat-Sen University, Guangzhou 510275, china 4national Climate center, china Meteorological Administration, beijing 100080, china 1. State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Department of Atmospheric Science Sun Yat-Sen University Guangzhou 510275 China4. National Climate Center China Meteorological Administration Beijing 100080 China

Physical processes associated with onset of the 1998 Asian summer monsoon were examined in detail using multi-source datasets. We demonstrated that strong ocean-atmosphere-land interaction in the northern Indian Ocean and tropical Asian area during spring is a fundamental factor that induces the genesis and development of a monsoon onset vortex over the Bay of Bengal (BOB), with the vortex in turn triggering onset of the Asian summer monsoon. In spring, strong surface sensible heating over India and the Indochina Peninsula is transferred to the atmosphere, forming prominent in situ cyclonic circulation, with anticyclonic circulations over the Arabian Sea and northern BOB where the ocean receives abundant solar radiation. The corresponding surface winds along the North Indian Ocean coastal areas cause the ocean to produce the in situ offshore currents and upwelling, resulting in sea surface temperature (SST) cooling. With precipitation on the Indochina Peninsula increasing from late April to early May, the offshore current disappears in the eastern BOB or develops into an onshore current, leading to SST increasing. A southwest-northeast oriented spring BOB warm pool with SST >31°C forms in a band from the southeastern Arabian Sea to the eastern BOB. In early May, the Somali cross-equatorial flow forms due to the meridional SST gradient between the two hemispheres, and surface sensible heat over the African land surface. The Somali flow overlaps in phase with the anticyclone over the northern Arabian Sea in the course of its inertial fluctuation along the equator. The convergent cold northerlies on the eastern side of the anticyclone cause the westerly in the inertial trough to increase rapidly, so that enhanced sensible heat is released from the sea surface into the atmosphere. The cyclonic vorticity forced by such sensible heating is superimposed on the inertial trough, leading to its further increase in vorticity strength. Since atmospheric inertial motion is destr

关键词： air-sea interaction spring BOB warm pool monsoon onset vortex inertial oscillation Asian summer monsoon onset

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Development of Rapidly Quenched Soft Magnetic Materials in china

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Journal of Materials Science & Technology 2000年第2期16卷 131-136页

作者： Shaoxiong ZHOU (national Amorphous and Nanocrystalline Alloy Engineering Research center, Central Iron and Steel Research Institute, beijing 100081, china) national Amorphous and Nanocrystalline Alloy Engineering Research center Central Iron and Steel Research Institute Beijing 100081 China

The discovery of the first Fe-based ferromagnetic amorphous alloy in 1966 had made an impact on conventional magnetic materials because of its unique properties. Since then, a number of amorphous magnetic materials have been successfully developed and used in a wide variety of applications. A brief review of R & D activities on amorphous soft magnetic materials in china is given from the beginning to the present in a somewhat chronological order, followed by a brief introduction to their applications on electric and electronic industries. An analysis and a prospect of Chinese market of such amorphous materials are also presented.

关键词： Development of Rapidly Quenched Soft Magnetic Materials in china

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Fluorescence dynamics of interactions between polyamide PyPyPyβDp and DNA

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Science china Chemistry 2006年第1期49卷 75-80页

作者： ZHANG Huijuan1,2, WANG Jin3, WU Yishi1, YUAN Gu3, AI Xicheng1, WANG Li4 & ZHANG Jianping1 1. State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, beijing 100080, china 2. School of Life Science and Technology, beijing Institute of Technology, beijing 100081, china 3. College of Chemistry and Molecular Engineering, Peking University, beijing 100080, china 4. center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, beijing 100080, china Correspondence should be addressed to Ai Xicheng and Zhang Jianping 1. State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China 2. School of Life Science and Technology Beijing Institute of Technology Beijing 100081 China 3. College of Chemistry and Molecular Engineering Peking University Beijing 100080 China 4. center for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China

The photophysical properties of the polyamide PyPyPyβDp (PPP) were investigated by means of steady-state absorption and fluorescence spectroscopies, as well as time-resolved fluo-rescence spectroscopy. It was found that the excited-state properties of PPP are very sensitive to solvents. In TKMC buffer PPP exhibited weak fluorescence with a decay time constant of 16 ps, while with the decrease of the solvent polarity PPP showed the blue-shifted peak position, increased inten-sity and lengthened life-time for its fluorescence behavior. In the presence of calf thymus DNA, it was observed that the fluorescence intensity was enhanced and the fluorescence lifetime increased from 16 to 32 ps for PPP, which verified that PPP bound into the minor groove of DNA duplex.

关键词： polyamide (PPP), calf thymus DNA (ctDNA), time-resolved fluorescence spectroscopy, recognition dynamics.

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Gas kinetic algorithm for flows in Poiseuille-like microchannels using Boltzmann model equation

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Science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 496-512页

作者： LI Zhihui1,2, ZHANG Hanxin1 & FU Song2 ⒈ national Laboratory for CFD, Hypervelocity Aerodynamics Institute,china Aerodynamics Research and Development center,Mianyang 621000,china 2.Department of Engineering Mechanics,Tsinghua University,beijing 100084,china 1. national Laboratory for CFD Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development Center 621000 Mianyang China 2. Department of Engineering Mechanics Tsinghua University 100084 Beijing China

The gas-kinetic unified algorithm using Boltzmann model equation have been extended and developed to solve the micro-scale gas flows in Poiseuille-like micro-channels from Micro-Electro-Mechanical Systems (MEMS). The numerical modeling of the gas kinetic boundary conditions suitable for micro-scale gas flows is presented. To test the present method, the classical Couette flows with various Knudsen numbers, the gas flows from short microchannels like plane Poiseuille and the pressure-driven gas flows in two-dimensional short microchannels have been simulated and compared with the approximate solutions of the Boltzmann equation, the related DSMC results, the modified N-S solutions with slip-flow boundary theory, the gas-kinetic BGK-Burnett solutions and the experimental data. The comparisons show that the present gas-kinetic numerical algorithm using the mesoscopic Boltzmann simplified velocity distribution function equation can effectively simulate and reveal the gas flows in microchannels. The numerical experience indicates that this method may be a powerful tool in the numerical simulation of micro-scale gas flows from MEMS.

关键词： Boltzmann model equation, discrete velocity ordinate method, finite-difference scheme, Couette flow, Poiseuille flow, gas flow in short-microchannel.

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Surface deformation at the epicenter of the May 12,2008 Wenchuan M8 Earthquake,at Yingxiu Town of Sichuan Province,china

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Science china(Technological Sciences) 2008年第S2期51卷 154-163页

作者： DONG ShaoPeng,HAN ZhuJun & AN YanFen national center of Seismic Fault Study,Institute of Geology,china Earthquake Administration,beijing 100029,china 1. national center of Seismic Fault Study Institute of Geology China Earthquake Administration Beijing 100029 China

Surface deformation,along national Highway 213 at the epicenter of Wenchuan M8 earthquake,at Yingxiu Town of Sichuan Province,china,is surveyed and measured in *** results show two distinct *** is that no horizontal displacement displays,or dextral strike-slip component at the observation point can not be found basically,the other is that uplift amount is 2.72 m,and the short-ening amount is 0.38 m,which reflects thrust shortening deformation is not *** crust uplift amount of 2.71 m is distributed in a belt with width of 60 *** model of lower crustal flow proposed by Royden et al.(1997) about the dynamic process in eastern margin of the Tibetan Plateau seems more suitable to explain the seismic surface deformation characteristics at Yingxiu Town,the epicenter of the May 12,2008 Wenchuan M8 Earthquake.

关键词： Wenchuan M8 Earthquake Yingxiu Town surface deformation

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