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Spectral analysis of quasi-stationary sea surface topography from GRACE mission

Science china Earth sciences 2005年第11期48卷 2040-2048页

作者： ZHANG Zizhan1,2.& LU Yang1,3.1. institute of Geodesy and Geophysics, Chinese academy of {2., Wuhan 43.077, china 2. Graduate School of the Chinese academy of {2., beijing 10003., china 3. Unite Center for Astro-geodymics Research, Chinese academy of {2., Shanghai 2.003., china 1. institute of Geodesy and Geophysics Chinese Academy of Sciences 430077 Wuhan China 2. Graduate School of the Chinese academy of sciences 100039 Beijing China 3. Unite Center for Astro-geodymics Research Chinese Academy of Sciences 200030 Shanghai China

During the last two decades satellite altimetry has offered an abundance of meas-urements of the sea surface resulting in the improvement of global mean sea surface height (MSSH) and marine geoid determination. On the other hand, with the launching of new genera-tion gravity satellites, some high accuracy long-wavelength gravity models are available. These breakthroughs give us a great opportunity for new estimation of quasi-stationary sea surface topography (QSST). In this paper, the new gravity model GGM01C derived from GRACE mission is briefly presented, and a new global high precision and high-resolution QSST is determined based on the GGM01C model and the global MSSH. The spectral features of the QSST esti-mated by GGM01C and EGM96 gravity model to degree/order 2.0 are discussed by spectral analysis. As a result, the QSST is mainly composed of long waves, medium waves partially and short waves scarcely, its power spectral structures are different between the zonal direction and the meridional direction, there are great differences between the two models, which maybe ex-plain why the ocean currents derived from the two gravity models by Tapley show different pat-terns.

关键词： quasi-stationary sea surface topography, mean sea surface height, GGM01, fast Fourier transform, spectral analysis

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STRANGE ATTRACTORS ON PSEUDOSPECTRAL SOLUTIONS FOR DISSIPATIVE ZAKHAROV EQUATIONS1

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Acta Mathematica Scientia 2004年第3期24卷 321-336页

作者： MaShuqing ChangQianshun instituteofapplied{2. theChineseAcademyofSciencesBeijing100080China

In this paper, the pseudospectral method to solve the dissipative Zakharov equations is used. Its convergence is proved by priori estimates. The existence of the global attractors and the estimates of dimension are presented. A class of steady state solutions is also disscussed. The numerical results show that if the steady state solutions satisfy some special conditions, they become unstable and limit cycles and strange attractors will occur for very small *** largest Lyapunov exponent and analysis of the linearized system are applied to explain these phenomena.

关键词： strange attractors psendospectral method Zakharov equations

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Physical mechanisms of plant roots affecting weathering and leaching of loess soil

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Science china Earth sciences 2006年第9期49卷 1002-1008页

作者： LI Yong1,2. ZHANG Qingwen1,2. WAN Guojiang3. HUANG Ronggui3. PIAO Hechun3. BAI Lingyu2.& LI Lu2.1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, institute of Soil and Water Conservation, Chinese academy of {2., Yangling 712.00, china 2. institute of Agro-Environment and Sustainable Development, Chinese academy of Agricultural {2., {13. 100081, china 3. institute of Geochemistry, Chinese academy of {2., Guiyang 550002. china 1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation Chinese Academy of Sciences Yangling 712100 China 2. institute of Agro-Environment and Sustainable Development Chinese Academy of Agricultural Sciences Beijing 100081 China 3. institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China

Plant roots have potential impacts on soil mineral weathering and *** objective is to understand the physical mechanisms of plant roots affecting weathering andleaching of loess soil. Root densities were measured through the method of a large-size dug profile,and transport fluxes of soil elements were determined using an undisturbed monolith soilinfiltration device on the hilly and gully regions of the Chinese Loess Plateau. The results showthat the improvement effects of soil environment by plant roots are mainly controlled by the densityand weight of the fibrous roots with the diameters less than 1 mm. Plant roots have the strongereffects on soil physical properties than chemical properties. The principal components analysis(PCA) indicates that soil physical properties by plant roots account for 56.7% of variations in soilenvironment whereas soil chemical properties and pH contribute about 2..2. of the soil *** roles of plant roots in controlling soil weathering and leaching increased in the followingorder: infiltration enhancement > increase of bio-active substance > stabilization of soilstructure. The effects of plant roots on soil mineral weathering and leaching can be quantifiedusing the multiple regression models with the high prediction accuracies developed in this study.

关键词： plant roots, soil weathering and leaching rates, soil environment field, principal components analysis (PCA), Chinese Loess Plateau.

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On exactness and unbiasedness of confidence bands for a continuous distribution function

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Science china mathematics 2010年第10期53卷 2665-2678页

作者： DING XiaoBo1,2.XU XingZhong2.& ZHAO ShuRan3.1institute of {3. {2.,academy of {2. and Systems Science,Chinese academy of sciences,beijing 100190,china 2.epartment of {2.,beijing institute of Technology,beijing 100081,china 3.chool of Economics,Ocean University of china,Qingdao 2.6071,china 1. institute of applied {2. Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China2. Department of Mathematics Beijing Institute of Technology Beijing 100081 China3. School of Economics Ocean University of China Qingdao 266071 China

We define a class of confidence bands for distribution functions,named simple confidence *** class of bands includes the common step bands and continuous bands,some of which may perform better than the smoothed bands not belonging to the class,e.g.,the kernel smoothed *** is shown that under some mild assumptions,the simple bands with exact coverage for continuous distribution functions are all step *** unbiasedness problem of the step bands is also *** is proved that most of two-sided step bands are biased and one-sided step bands are unbiased.

关键词： exact coverage goodness of fit kernel smoothing simple confidence bands unbiasedness

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Boundedness of Solutions in Asymmetric Oscillations via the Twist Theorem

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Acta Mathematica Sinica,English Series 2001年第2期17卷 313-318页

作者： Yi Qian WANG institute of mathematics. {2. of mathematics and Systems sciences. Chinese {2. of Science, beijing 100080 P. R. china institute of mathematics Academy of Mathematics and Systems Sciences Chinese Academy of Science Beijing 100080 P. R. China

In this paper we consider the boundedness of all the solutions for the equation x'+ax^+ -bx^-=f(t). where f(t) is a smooth 2.-periodic function, a and b are positive constants (a≠b).

关键词： Boundedness Asymmetric Canonical transformation Twist theorem

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VARIABLE SELECTION BY PSEUDO WAVELETS IN HETEROSCEDASTIC REGRESSION MODELS INVOLVING TIME SERIES

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Acta Mathematica Scientia 2006年第3期26卷 469-476页

作者：王清河周勇 Department of applied mathematics University of Petroleum Shandong 257062China institute of applied {2. {3. of {2. and Systems Science The Chinese {3. of sciences Beijing 100080China

A simple but efficient method has been proposed to select variables in heteroscedastic regression models. It is shown that the pseudo empirical wavelet coefficients corresponding to the significant explanatory variables in the regression models are clearly larger than those nonsignificant ones, on the basis of which a procedure is developed to select variables in regression models. The coefficients of the models are also estimated. All estimators are proved to be consistent.

关键词： Heteroscedastic regression models variable selection wavelets

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GLIVENKO-CANTELLI TYPE THEOREMS ANDTHEIR APPLICATIONS

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Acta Mathematica Scientia 1997年第3期17卷 309-318页

作者：朱力行 ACAD SINICA INST APPL MATHPROBABIL LABBEIJING 100080PEOPLES R CHINA

In this paper, we present a sufficient condition for uniform convergence of means to their expectations over the classes of real functions. Our proof is very simple via connecting this convergence to uniform convergence over the class of indicator functions. Furthermore, we obtain a convergent result concerning a non=VC class with an application to variable transformation for fitting regression model.

关键词： uniform convergence non-VC class of functions variable transformation method

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A V-CYCLE MUTIGRID FOR QUADRILATERAL ROTATED Q_1 ELEMENT WITH NUMERICAL INTEGRATION

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Journal of Computational mathematics 2003年第5期21卷 545-554页

作者： Zhong-ci Shi Xue-jun Xu(LSEC, institute of Computational mathematics, {2. of mathematics and System sciences, Chinese {2. of sciences, beijing 100080, china) 中科院数学与系统科学院 LSEC CAS 北京 100080

In this paper, a V-cycle multigrid method is presented for quadrilateral rotated elements with numerical integration.

关键词： Multigrid Rotated Q1 elements Numerical integration.

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Experimental and discrete element numerical analysis of side slope instability induced by fissure water underlying impervious bed

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Science china(Technological sciences) 2005年第z1期48卷 65-80页

作者： LIU Bingshan1, LI Shihai1, ZHANG Lei1,2.& WANG Jianguo3.. institute of Mechanics, Chinese academy of {2., beijing 100080, china 2. Graduate School, Chinese academy of {2., beijing 100060, china 3. Tropical Marine Science institute, National University of Singapore, 10 Kent Ridge Crescent, Singapore 1192.0 Chinese Acad Sci Inst Mech Beijing 100080 Peoples R China Chinese Acad Sci Grad Sch Beijing 100060 Peoples R China Natl Univ Singapore Trop Marine Sci Inst Singapore 119260 Singapore

When the sliding mass contains impervious bed, rainfall can infiltrate into mountain via crevices and form higher artesian aquifer at impervious bed inferior. This will decrease slip resistance and increase sliding forces of the sliding mass, thus lowering the safety factor, and inducing landslide disasters. In this paper, a landslide experimental apparatus is designed for experimental studies on the mechanism of this type of landslides. Meanwhile, the non-dimensional parameters in the model experiment are taken into account using dimensional analysis. The experimental results show that (1) the ratio of the cleft water pressure to the overlying pressure is a crucial parameter affecting the stability of the slope; (2. when the shut-in pressure reaches 80% of the normal component of the pressure on the slip surface made up of rock and soil, landslide will occur; (3. the whole slope will start to slide when the shut-in pressure is equal to the normal component of the pressure formed by the overlying rock and soil on the upper 3.% area. In this article, a discrete element method simulation is used to investigate the influence of cleft water pressure and shearing strength on the landslide stability. It can be concluded that the critical value of Ccr, ?cr, which determines the slide mass stability, increases with the increase of the water pressure; if the water pressure reaches a high level, the stability of the slide mass depends mainly on C, while the influence of ? becomes smaller than C.

关键词： impervious bed, rainfall infiltration, pore water pressure, landslide experiment, displacement monitor, discrete element method.

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Role of gallium wetting layer in high-quality ZnO growth on sapphire (0001) substrates

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Science china(Physics,Mechanics & Astronomy) 2004年第5期47卷 612-620页

作者： ZENG Zhaoquan1,3. WANG Yong2. DU Xiaolong1, MEI Zengxia1, KONG Xianghe3. JIA Jinfeng1, XUE Qikun1 & ZHANG Ze2. 4 1. State Key Laboratory for Surface Physics, institute of Physics, Chinese {3. of {2., beijing 100080, china 2. Laboratory of Electron Microscopy, institute of Physics, Chinese {3. of {2., beijing 100080, china 3. College of Physics and Engineering, Qufu Normal University, Qufu 2.3.65, china 4. beijing University of Technology, beijing 10002., china 1. State Key Laboratory for Surface Physics Institute of Physics Chinese Academy of Sciences 100080 Beijing China 2. College of Physics and Engineering Qufu Normal University 273165 Qufu China 3. Laboratory of Electron Microscopy Institute of Physics Chinese Academy of Sciences 100080 Beijing China 4. beijing University of Technology 100022 Beijing China

A Ga wetting layer was used to modify the surface structure of sapphire (0001) substrate to prepare high-quality ZnO film by radio frequency plasma-assisted molecule beam epitaxy. We found that this Ga layer plays a crucial role in eliminating 3. rotation domains, controlling polarity and decreasing defect density in ZnO epilayers, as demonstrated by in situ reflection high energy electron diffraction, ex situ high resolution X-ray diffraction and high resolution cross-sectional transmission electron microscopy. Zn-polar film of ZnO was determined by convergent beam electron diffraction. A Ga bilayer model is proposed to understand the effects of the Ga wetting layer on high-quality ZnO growth.

关键词： Ga wetting layer, sapphire, polarity, defect density, zinc oxide, rf-MBE, RHEED, HRXRD, TEM, CBED.

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