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Study on NDVI-T_s space by combining LAI and evapotranspiration

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science china Earth sciences 2006年第7期49卷 747-754页

作者： HAN Lijuan1,2.3, WANG Pengxin4, YANG Hua1,2.3, LIU Shaomin1,2.3 & WANG Jindi1,2.3 1. Research Center for Remote Sensing and GIS, School of Geography, beijing normal university, beijing 100875,{2. 2. State Key Laboratory of Remote Sensing science, beijing 100875,{2. 3. beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, beijing 100875,{2. 4. department of Information Management, College of Information and Electronic engineering,{2. Agricultural {12., beijing 100083,{2. 1. Research Center for Remote Sensing and GIS School of Geography Beijing Normal University Beijing 100875 China 2. State Key Laboratory of Remote Sensing science Beijing 100875 China 3. beijing Key Laboratory for Remote Sensing of Environment and Digital Cities Beijing 100875 China 4. department of Information Management College of Information and Electronic Engineering China Agricultural University Beijing 100083 China

This paper focuses on interpreting the different spatial relationships between NDVI and Ts, a triangular or a trapezoid, and on analyzing transformation conditions, the physical and ecological meanings of the vegetation index-surface temperature space as well. Further, we use the Tempera-ture-Vegetation Dryness Index (TVDI) to explain the existent meaning of a triangular space after NDVI reaches its saturated state by employing the relationships between NDVI, LAI and evapotranspiration. The specific relations between NDVI and Ts are useful for describing, validating and updating land surface models.

关键词： NDVI, land surface temperature, evapotranspiration, leave area index.

Linear operators preserving the generalized decomposable numerical range

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Chinese science Bulletin 1997年第1期42卷 22-26页

作者： LEI Tiangangdepartment of Mathematics, beijing normal university,{2., china department of Mathematics Beijing Normal University Beijing 100875 China

LET G be a subgroup of the symmetric group Sm. Denote by CG the set of all functions f: G→C. A function f∈CG is said to be positive semi-definite （p. s. d. ） if there exists c∈CG such that for all τ∈G. In particular, the irreducible complex characters of G are p. s. d. Let Cn×m denote the set of all n×m complex matrices. For f∈CG, the

关键词： decomposable numerical range linear operator positive semi-definite function generalized matrix function.

Homology classes that can be represented by embedded spheres in rational surfaces

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science china Mathematics 2004年第3期47卷 431-439页

作者： GAO Hongzhu GUO Ren department of Mathematics,beijing {2. university, beijing 100875,china 1. department of Mathematics Beijing Normal University 100875 Beijing China

The problem of embedding spheres in rational surfaces CP 2.n $\overline {CP} $ 2.is studied. For homology classes u = (b 1 + k, b 2....,b n) with positive self-intersection numbers, a necessary and sufficient conditio... 详细信息

关键词： four manifold embedded sphere self-intersection number

Effects of Si Content and the Addition Amount of Al-3B Master Alloy on the Solidification Structures of Hypoeutectic Al-Si Alloys

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Rare Metals 2001年第3期20卷 168-173页

作者： Donghui Wang,Jianguo Li, Yankang Zheng, Bingzhe Bai department of materials {2. and engineering, Tsinghua university, beijing 100084, china Tsing Hua Univ Dept Mat Sci & Engn Beijing 100084 Peoples R China

Effects of Si content and the addition amount of Al-3B master alloy on the solidification structures of hypoeutectic Al-Si alloys were studied. The addition amounts of the master alloy were 0.2., 0.4%, 0.7% and 1% (mass fraction, so as the follows), respectively. The Si content of Al-Si binary alloys investigated varied from 1% to 11%. The observation of macrostructures of non-refined samples showed that 3% Si constitutes a transition point at which the minimum grain size can be obtained. It was also found that Al-3B master alloy can shift the transition point towards a higher Si value when its addition amount increases, making this point appear at 4%, 5% and 6% Si as its addition amount increases up to 0.4%, 0.7% and 1%, respectively.

关键词： Al-3B master alloy hypoeutectic Al-Si alloy grain refinement

Theoretical study on the reaction mechanism of (CH3)3CO(.) radical with NO

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science china Chemistry 2004年第4期47卷 289-294页

作者： ZHAO Hongmei1,2. LIU Kun1, SUN Chengke1 & LI Zonghe1 1. department of Chemistry, beijing normal university,{2., china 2. department of Chemistry, Beihua university, Jilin 132.13, china 1. department of Chemistry Beijing Normal University 100875 Beijing China 2. department of Chemistry Beihua University 132013 Jilin China

The reaction mechanism of (CH3)3CO? radical with NO is theoretically investigated at the B3LYP/6-31G* level. The results show that the reaction is multi-channel in the single state and triplet state. The potential energy surfaces of reaction paths in the single state are lower than that in the triple state. The balance reaction: (CH3)3CONO(CH3)3CO?+NO, whose potential energy surface is the lowest in all the reaction paths, makes the probability of measuring (CH3)3CO? radical increase. So NO may be considered as a stabilizing reagent for the (CH3)3CO? radical.

关键词： (CH3)3CO. radical DFT reaction mechanism NO

Representation type of 0-Hecke algebras

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science china Mathematics 2011年第3期54卷 411-420页

作者： DENG BangMing1 & YANG GuiYu2.1department of Mathematics, beijing normal university,{2., china 2.chool of science, Shangdong university of Technology, Zibo 2.5049, china 1. department of Mathematics Beijing Normal University Beijing 100875 China2. School of Science Shangdong University of Technology Zibo 255049 China

In the present paper we determine the representation type of the 0-Hecke algebra of a finite Coxeter group.

关键词： Coxeter group 0-Hecke algebra representation type

Fuzzy controllers based on some fuzzy implication operators and their response functions

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Progress in Natural science:materials International 2004年第1期14卷 16-21页

作者： LI Hongxing 1*, YOU Fei 1 and PENG Jiayin 2.1. department of Mathematics, beijing normal university,{2., china 2. department of Mathematics, Neijiang Teacher's College, Neijiang 641112. china) beijing normal Univ Dept Math Beijing 100875 Peoples R China

The fuzzy controllers constructed by 2. fuzzy implication operators based on CRI algorithm and their response functions are discussed. The conclusions show that the fuzzy controllers constructed by 9 fuzzy implication operators are universal approximators to continuous functions and can be used in practical fuzzy control systems. And these 9 fuzzy implication operators except for Einstein operator intersection are all the adjoint pairs of some fuzzy implication operators. Besides, there are 3 other fuzzy controllers formed by fuzzy implication operators being regarded approximately as fitted functions.

关键词： fuzzy implication operators CRI algorithm fuzzy controllers response functions universal approximators

Effects of Na/K ratio on the phase structure and electrical properties of Na_xK_(1-x)NbO_3 lead-free piezoelectric ceramics

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Rare Metals 2010年第2期29卷 220-225页

作者： ZHANG Qian, ZHANG Boping, Li Haitao, and SHANG Pengpeng School of materials science and {2., university of science and Technology beijing, beijing 100083, china School of materials science and {2. University of Science and Technology Beijing

Lead-free piezoelectric NaxK1-xNbO3（x = 0.3-0.8）（NKN） ceramics were fabricated by normal sintering at 1060°C for 2.*** and electrical properties of the ceramics were investigated with a special emphasis on the influence of Na *** grain size of the produced dense ceramic was decreased by increasing Na content.A discontinuous change in the space distance was found at the composition close to Na0.7K0.3NbO3 ceramic, which indicates the presence of a transitional composition between two different orthorhombic phases, which is similar to the behavior of morphotropic phase boundary（MPB） in NaxK1-xNbO3 *** MPB-like behavior contributes to the enhanced piezoelectric coefficient d33 of 12. pC/N, planar-mode electromechanical coupling coefficient kP of 2..6%, and dielectric constant εr of 703, respectively for the Na0.7K0.3NbO3 *** temperature TC and the transitional temperature TO-T from orthorhombic to tetragonal phase are observed at around 42.°C and 2.0°C, respectively.

关键词： lead-free piezoelectric ceramics NKN sintering morphotropic phase boundary(MPB)

Quasi-Carbon Fibers and the Composites

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Journal of materials science & Technology 2000年第5期16卷 486-490页

作者： Lulu SONG, Weihong ZHONG+, Zuoguang ZHANG and Zhijie SUN (department of materials {2. & engineering, beijing university of Aeronautics and Astronautics, beijing 100083, china) department of materials {2. and engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The aim of this report is to study the properties of quasi-carbon fibers (QCF) prepared from the PAN fiber precursor by pyrolysis at a temperature between 400℃ and 12.0℃. The resistivity of QCF with different heat-treated temperature (HTT) was investigated by a Hall-35 testing system, and the flexural properties of the result composites (QCFC) are also discussed. In addition, the scanning electronic microscope (SEM) was utilized to observe the surface morphology of QCF and the fracture section of QCFC obtained from flexural testing.

关键词： QCF Quasi-Carbon Fibers and the Composites HTT