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Journal of Computational Mathematics 2000年第5期18卷 449-456页

作者： Zhen-dong Luo (department of Mathematics, Capital normal university, beijing 100057, china) 首都师范大学北京 100037

In this paper, the method of non-conforming mixed finite element for second order elliptic problems is discussed and a format of real optimal order for the lowest order error estimate.

关键词： Non-conforming mixed finite element Error estimate Second order elliptic problems.

Retrieving crop leaf area index by assimilation of MODIS data into a crop growth model

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Science china Earth Sciences 2010年第5期53卷 721-730页

作者： WANG DongWei1,2,3, WANG JinDi1,2 & LIANG ShunLin4 1 State Key Laboratory of Remote Sensing Science, Jointly Sponsored by beijing normal university and Institute of Remote Sensing Applications, CAS, beijing 100875, china 2 School of Geography, beijing Key Laboratory of Environmental Remote Sensing and Digital City, beijing normal university, beijing 100875, china 3 Haihe River Water Conservancy Commission, Tianjin 300170, china 4 department of Geography, university of Maryland, College Park, MD 20742, USA 1. State Key Laboratory of Remote Sensing Science Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing Applications CAS Beijing 100875 China2. School of Geography Beijing Key Laboratory of Environmental Remote Sensing and Digital City Beijing Normal University Beijing 100875 China3. Haihe River Water Conservancy Commission Tianjin 300170 China4. Department of Geography University of Maryland College Park MD 20742 USA

Leaf area index (LAI) is an important parameter in monitoring crop growth. One of the methods for retrieving LAI from remotely sensed observations is through inversion of canopy reflectance models. Many model inversion methods fail to account for variable LAI values at different crop growth stages. In this research, we use the crop growth model to describe the LAI changes with crop growth, and consider a priori LAI values at different crop growth stages as constraint information. The key approach of this research is to assimilate multiple canopy reflectance values observed at different growth stages and a priori LAI values into a coupled crop growth and radiative transfer model sequentially using a variational data assimilation algorithm. Adjoint method is used to minimize the cost function. Any other information source can be easily incorporated into the inversion cost function. The validation results show that the time series of MODIS canopy reflectance can greatly reduce the uncertainty of the inverted LAI values. Compared with MODIS LAI product at Changping and Shunyi Counties of beijing, this method has significantly improved the estimated LAI temporal profile.

关键词： inversion leaf area index crop growth model time series MODIS

THE PHYSICAL ENTROPY OF SINGLE CONSERVATION LAWS

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Journal of Computational Mathematics 1998年第5期16卷 437-444页

作者： (department of Mathematics, Peking university, beijing 100871, china) beijing Univ Dept Math Beijing 100871 Peoples R China

By means of the comparisons with the formulas in statistical mechanics and thermodynamics, in this paper it is demonstrated that for the single conservation law partial derivative(t)u + partial derivative(x)f(u) = 0, if the flux function f(u) is convex (or concave), then, the physical entropy is S = -f(u); Furthermore, if we assume this result can be generalized to any f(u) with two order continuous derivative, from the thermodynamical principle that the local entropy production must be non-negative, one entropy inequality is derived, by which the O.A. Olejnik's famous E- condition can be explained successfully in physics.

关键词： conservation laws entropy entropy production

Quality evaluation for air plasma spray thermal barrier coatings with pulsed thermography

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Progress in Natural Science:Materials International 2011年第4期21卷 301-306页

作者： Shi-bin ZHAO~1,Cun-lin ZHANG~2,Nai-ming WU~3,Hua-ming WANG~1 1.School of Materials Science and Engineering,Beihang university,beijing 100191,china 2.department of Physics,Capital normal university,beijing 100048,china 3.School of Jet Propulsion,Beihang university,beijing 100191,china [a] School of Materials Science and Engineering Beihang University Beijing 100191 China [b] department of Physics Capital Normal University Beijing 100048 China [c] School of Jet Propulsion Beihang University Beijing 100191 China

Pulsed thermography(PT) as a non-contact non-destructive evaluation(NDE) technique was employed to examine as-sprayed air plasma spray(APS) thermal barrier coatings(TBCs) for quality *** and micro-structural characteristics play a vital role in determining the *** this paper,PT logarithmic peak second-derivative method was adopted to measure the thickness of top *** dependent thermal images were used to characterize the microstructure which was confirmed by scanning electron microscope(SEM).The results showed that there was relationship between the temperature distribution of the surface and microstructure change in *** distribution in thermal images and measurement results of thickness were in fairly good agreement with the microstructure *** can be concluded that it was possible to employ these NDE methods as quality evaluation for as-sprayed TBCs.

关键词： thermal barrier coatings(TBCs) non-destructive evaluation(NDE) pulsed thermography microstructure thickness measurement

Theoretical Study of Impact of Side Substituent Effecton Intramolecular Proton Transfer of Perylenequinone

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Chinese Chemical Letters 1999年第4期10卷 317-320页

作者： Ying QIAN Yan WANG Ruo Zhuang LIU(department of Chemical and Environmental Engineering, beijing Polytechnic university, Beliing100022)(department of Chemistry, beijing normal university, beijing 100875) beijing Polytech Univ Dept Chem & Envirom Engn Beijing 100022 Peoples R China beijing normal Univ Dept Chem Beijing 100875 Peoples R China

Semi-empirical molecular orbital theory AMI method is employed to study the ortho-position substituent impact on intramolecular proton transfer reaction of perylenequinone. The calculation demonstrates that the perylenequinone molecule is of stable structure. and all substituents may cause the decrease of barriers for the hydrogen transfer reaction.

关键词： perylenequinone AM1 method proton transfer substituent effect

Binary population synthesis study of the supersoft X-ray phase of single degenerate type Ia supernova progenitors

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Research in astronomy and Astrophysics 2011年第8期11卷 965-973页

作者： Xiang-Cun Meng Wu-Ming Yang School of Physics and Chemistry Henan Polytechnic University Jiaozuo 454000 China department of astronomy Beijing Normal University Beijing 100875 China

In the single degenerate （SD） scenario for type Ia supernovae （SNe Ia）, a mass-accreting white dwarf is expected to experience a supersoft X-ray source （SSS） phase. However, some recent observations showed that the expected number of massaccreting WDs is much lower than that predicted from theory, regardless of whether they are in spiral or elliptical galaxies. In this paper, we performed a binary population synthesis study on the relative duration of the SSS phase to their whole mass-increasing phase of WDs leading to SNe Ia. We found that for about 40% of the progenitor systems, the relative duration is shorter than 2% and the evolution of the mean relative duration shows that it is always smaller than 5%, both for young and old SNe Ia. In addition, before the SNe Ia explosions, more than 55% of the progenitor systems were experiencing a dwarf novae phase and no more than 10% were staying in the SSS phase. These results are consistent with the recent observations and imply that both in early- and late-type galaxies, only a small fraction of mass-accreting WDs resulting in SNe Ia contributes to the supersoft X-ray flux. So, although our results are not directly related to the X-ray output of the SN Ia progenitor, the low supersoft X- ray luminosity observed in early type galaxies may not be able to exclude the validity of the SD model. On the contrary, it is evidence to support the SD scenario.

关键词： stars: white dwarfs -- stars: supernovae: general

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, beijing 100875, 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 23 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

Reading comprehension without phonological mediation:Further evidence from a Chinese aphasic individual

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Science china(Life Sciences) 2009年第5期52卷 492-499页

作者： HAN ZaiZhu & Bi YanChao State Key Laboratory of Cognitive Neuroscience and Learning, beijing normal university, beijing 100875, china State Key Laboratory of Cognitive Neuroscience and Learning Beijing Normal University Beijing 100875 China

An important issue in visual word comprehension literature is whether or not semantic access is mediated by phonological processing. In this paper, we present a Chinese individual, YGA, who provides converging evidence to directly address this issue. YGA has sustained damage to the left posterior superior and middle temporal lobe, and shows difficulty in orally name pictures and reading printed words aloud. He makes phonological errors on these tasks and also semantic errors on picture naming, indicating a deficit at accessing the phonological representations for output. However, he is intact at understanding the meaning of visually presented words. Such a profile challenges the hypothesis that semantic access in reading is phonologically mediated and provides further evidence for the universal principle of direct semantic access in reading.

关键词： word reading phonological mediation Chinese case study

Asymptotic distributions in the projection pursuit based canonical correlation analysis

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Science china Mathematics 2010年第2期53卷 485-498页

作者： JIN Jiao & CUI HengJian department of Statistics and Financial Mathematics, School of Mathematical Sciences, beijing normal university, Laboratory of Mathematics and Complex Systems (beijing normal university), Ministry of Education, beijing 100875, china 1. department of Statistics and Financial Mathematics School of Mathematical Sciences Beijing Normal University Beijing 100875 China2. Ministry of Education Laboratory of Mathematics and Complex Systems (Beijing Normal University) Beijing 100875 China

In this paper, associations between two sets of random variables based on the projection pursuit (PP) method are studied. The asymptotic normal distributions of estimators of the PP based canonical correlations and we... 详细信息

关键词： asymptotic distribution canonical correlation analysis influence function robust statistics

Cu(Ⅱ) Potentiation of Alzheimer Aβ1-40 Cytotoxicity and Transition on its Secondary Structure

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Acta Biochimica et Biophysica Sinica 2006年第11期38卷 765-772页

作者： Xue-Ling DAI~1 Ya-Xuan SUN~2 Zhao-Feng JIANG~2* 1 College of Life Science,Capital normal university,beijing 100037,china 2 College of Applied Sciences and Humanities,beijing Union university,beijing 100083,china College of Life Science Capital Normal UniversityBeijing 100037 China College of Applied Sciences and Humanities Beijing Union UniversityBeijing 100083 China

Mounting evidence has shown that dyshomeostasis of the redox-active biometals such as Cuand Fe can lead to oxidative stress,which plays a key role in the neuropathology of Alzheimer's disease（AD）.Here we demonstrate that with the formation of Cu（Ⅱ）·Aβ1-40 complexes,copper markedly potentiatesthe neurotoxicity exhibited by β-amyloid peptide （Aβ）.A greater amount of hydrogen peroxide was releasedwhen Cu（Ⅱ）·Aβ1-40 complexes was added to the xanthine oxidase/xanthine system detected by potassiumiodide *** bound to Aβ1-40 was observed by electron paramagnetic resonance（EPR） *** dichroism （CD） studies indicated that copper chelation could cause a structuraltransition of Aβ.The addition of copper to Aβ introduced an increase on β-sheet as well as α-helix,whichmay be responsible for the aggregation of Aβ.We hypothesized that Aβ aggregation induced by copper maybe responsible for local injury in *** interaction between Cu2+and Aβ also provides a possible mechanismfor the enrichment of metal ions in amyloid plaques in the AD brain.

关键词： Alzheimer’s disease Cu(Ⅱ)·Aβ1-40 complex neuron injury Aβ secondary structure