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

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 {2., 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 2.742. 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

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A priori estimates for classical solutions of fully nonlinear elliptic equations

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Science China Mathematics 2011年第3期54卷 457-462页

作者： CAO Yi1, LI DongSheng1 & WANG LiHe1,2.1College of Science, Xi’an Jiaotong university, Xi’an 710049, China 2.1} of Mathematics, The university of Iowa, Iowa city, IA 52.42.1419, usa 1. College of Science Xi’an Jiaotong University Xi’an 710049 China2. Department of Mathematics The University of Iowa Iowa City IA 52242-1419 USA

For the fully nonlinear uniformly elliptic equation F(D2.) = 0, it is well known that the viscosity solutions are C2.α if the nonlinear operator F is convex (or concave). In this paper, we study the classical solutions for the fully nonlinear elliptic equation where the nonlinear operator F is locally C1,β a.e. for any 0 utions u are C2.α. Moreover, the C2.α norm of u depends on n,F and the continuous modulus of D2..

关键词： fully nonlinear classical solutions C2 α estimates

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Correlation of zeros of automorphic L-functions

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Science China Mathematics 2008年第7期51卷 1147-1166页

作者： LIU JianYa1 & YE YangBo1,2.1 School of Mathematics,Shandong university,Jinan 2.0100, China 2.1} of Mathematics,The university of Iowa,Iowa city,IA 52.42.1419,usa 1. School of Mathematics Shandong University Jinan 250100 China 2. department of Mathematics The University of Iowa Iowa City IA 52242-1419 USA

We compute the n-level correlation of normalized nontrivial zeros of a product of Lfunctions: L(s, π1) … L(s, π k ), where πj, j = 1, …, k, are automorphic cuspidal representations of GL mj (?A). Here the sizes of the groups GL mj (?A) are not necessarily the same. When these L(s, π j ) are distinct, we prove that their nontrivial zeros are uncorrelated, as predicted by random matrix theory and verified numerically. When L(s, π j ) are not necessarily distinct, our results will lead to a proof that the n-level correlation of normalized nontrivial zeros of the product L-function follows the superposition of Gaussian Unitary Ensemble (GUE) models of individual L-functions and products of lower rank GUEs. The results are unconditional when m 1, …, m k ? 4, but are under Hypothesis H in other cases.

关键词： automorphic L-function zero correlation Selberg’s orthogonality conjecture 11F70 11M2. 11M41

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Resonance between automorphic forms and exponential functions

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Science China Mathematics 2010年第9期53卷 2463-2472页

作者： REN XiuMin1,& YE YangBo1,2.1School of Mathematics,Shandong university,Jinan 2.0100,China 2.1} of Mathematics,The university of Iowa,Iowa city,Iowa 52.42.1419,usa 1. School of Mathematics Shandong University Jinan 250100 China2. Department of Mathematics The University of Iowa Iowa City Iowa 52242-1419 USA

Let f be a holomorphic cusp form of weight k for SL2.Z) and λf(n) its n-th Fourier *** this paper,the exponential sum X2. λf(n)e(αnβ) twisted by Fourier coefficients λf(n) is proved toh ave a main term of size |λf(q)|X3/4 when β = 1/2.and α is close to ±2.q,q ∈ Z,and is smaller otherwise for β utomorphic forms for SL2.Z).

关键词： automorphic form exponential sum resonance

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Fast velocity analysis by wave path migration

Fast velocity analysis by wave path migration

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中国科学院地质与地球物理研究所第十届(2.10年度)学术年会

作者： Yike Liu~(1*++),Hongchuan Sun~(2.+) and Xu Chang~1 1 Institute of Geology and Geophysics,Chinese Academy of Sciences,10002. Beijing,China,and 2.Veritas DGC Inc.,10300 Town Park Drive,Houston,TX 77072.usa Formerly at department of Geology and Geophysics,{2.,salt lake city,ut 84112.usa

Iterative migration velocity analysis is computationally expensive,where most of the computation time is used for generating prestack depth *** using a reduced form of Kirchhoff migration,denoted as wave path migration,we can significantly speed up the depth imaging process and reduce the entire velocity analysis expense *** results with 2. synthetic and field data show that wave path migration velocity analysis can efficiently improve the velocity model and the wave path migration velocity analysis updated velocity correlates well with that from the Kirchhoff migration velocity *** central processing unit comparison shows that,for a 2. synthetic and field data set,wave path migration velocity analysis is six times faster than Kirchhoff migration velocity *** efficiency should be even greater for 3D data.

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Lower Velocities beneath the Taihang Mountains,Northeastern China

Lower Velocities beneath the Taihang Mountains,Northeastern ...

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中国科学院地质与地球物理研究所2.07学术年会

作者： Xu Chang,Yike Liu,Jiankun He,and Hongchuan Sun Institute of Geology and Geophysics Chinese Academy of Sciences Beijing,10002.,China Yangtze university Jingzhou,China department of Geology and Geophysics {2. salt lake city,utah,84112

We used regional P-wave arrival times to invert for 3D velocity structures beneath the Taihang Mountains,which are bordered by the intensely active zones of the Shanxi rift to the west and the eastern plain basin to the east in the North China Block.P-wave velocities show that low velocities(- 1.0 to -3.0%) are focused at depths of～15-2. km beneath the Taihang Mountains,similar to those beneath the active zones of the Shanxi rift and the eastern plain basin,If the lower velocity is representative of weakness in the underlying crust,there our results indicate that the Taihang Mountains might be potentially active,because the structure patterns are similar to their bounding active *** seismic research,therefore, should strongly focus on the Taihang Mountains.

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解决中央处理器运算速度与内存系统性能矛盾的一种方案

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计算机工程与应用 2002年第6期38卷 86-89页

作者：续敏汪小涓曲阜师范大学电教系曲阜273165

中央处理器-存储器集成是解决当前处理器运算速度与传统的存储器系统性能滞后的一种新思路。文章运用一个简单的评价模型和模拟运行,分析了几种处理器-存储器集成的方案。

关键词：中央处理器存储器高速缓存集成性能运算速度内存系统

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A statistical model for porous structure of rocks

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Science China(Technological Sciences) 2008年第11期51卷 2040-2058页

作者： JU Yang1,2. YANG YongMing1, SONG ZhenDuo3 & XU WenJing4 1 State Key Laboratory of Coal Resources and Safe Mining, China university of Mining & Technology, Beijing 100083, China 2.department of Mechanical and Manufacturing Engineering, The university of Calgary, 2.00 university Drive NW Calgary, AB T2. 1N4, Canada 3 China National Coal Mining Equipment Co. Ltd, Beijing 100011, China 4 department of Materials and Metallurgy, The university of utah, salt lake city, utah 84112, usa State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology Beijing 100083 China department of Mechanical and Manufacturing Engineering The University of Calgary 2500 University Drive NW Calgary Calgary AB T2N 1N4 Canada China National Coal Mining Equipment Co. Ltd Beijing 100011 China department of Materials and Metallurgy The University of Utah Salt Lake City Utah 84112 USA

The geometric features and the distribution properties of pores in rocks were in- vestigated by means of CT scanning tests of sandstones. The centroidal coordi- nates of pores, the statistic characterristics of pore distance, quantity, size and their probability density functions were formulated in this paper. The Monte Carlo method and the random number generating algorithm were employed to generate two series of random numbers with the desired statistic characteristics and prob- ability density functions upon which the random distribution of pore position, dis- tance and quantity were determined. A three-dimensional porous structural model of sandstone was constructed based on the FLAC3D program and the information of the pore position and distribution that the series of random numbers defined. On the basis of modelling, the Brazil split tests of rock discs were carried out to ex- amine the stress distribution, the pattern of element failure and the inosculation of failed elements. The simulation indicated that the proposed model was consistent with the realistic porous structure of rock in terms of their statistic properties of pores and geometric similarity. The built-up model disclosed the influence of pores on the stress distribution, failure mode of material elements and the inosculation of failed elements.

关键词： porous structure statistical model random numbers reconstruction rocks

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Mining and Integrating Reliable Decision Rules for Imbalanced Cancer Gene Expression Data Sets

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Tsinghua Science and Technology 2012年第6期17卷 666-673页

作者： Hualong Yu 1 , Jun Ni 2., Yuanyuan Dan 3 , Sen Xu 4 1. School of Computer Science and Engineering, Jiangsu university of Science and Technology, Zhenjiang 2.2.03, China 2. department of Radiology, Carver College of Medicine, The university of Iowa, Iowa city, IA 52.42. usa 3. School of Biology and Chemical Engineering, Jiangsu university of Science and Technology, Zhenjiang 2.2.03, China 4. School of Information Engineering, Yancheng Institute of Technology, Yancheng 2.4051, China School of Computer Science and Engineering Jiangsu University of Science and Technology Zhenjiang 212003 China|c|

There have been many skewed cancer gene expression datasets in the post-genomic era. Extraction of differential expression genes or construction of decision rules using these skewed datasets by traditional algorithms will seriously underestimate the performance of the minority class, leading to inaccurate diagnosis in clinical trails. This paper presents a skewed gene selection algorithm that introduces a weighted metric into the gene selection procedure. The extracted genes are paired as decision rules to distinguish both classes, with these decision rules then integrated into an ensemble learning framework by majority voting to recognize test examples; thus avoiding tedious data normalization and classifier construction. The mining and integrating of a few reliable decision rules gave higher or at least comparable classification performance than many traditional class imbalance learning algorithms on four benchmark imbalanced cancer gene expression datasets.

关键词： cancer gene expression data class imbalance paired differential expression genes decision ruleensemble learning majority voting

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Wetland hydrologic application of satellite altimetry-A case study in the Poyang lake watershed

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Progress in Natural Science:Materials International 2009年第12期19卷 1781-1787页

作者： Xiaobin Cai~(a,b),Wei Ji~(b,*) a State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,Wuhan university,Wuhan 430079,China b department of Geosciences,university of Missouri,Kansas city,Kansas city,MO 64110,usa [a]State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan 430079 China [b]department of Geosciences University of Missouri Kansas City Kansas City MO 64110 USA

Hydrologic variation affects many functions of *** and accurately measuring hydrologic dynamics in a wetland watershed has become a fundamental need for estimating functional changes of *** satellite altimeters have become good data sources that can complement the measurements of gauge *** a case project applied in the Poyang lake watershed,this study has developed a technical approach that integrates the altimeter measurements with the in situ water level *** derived water surface heights with Envisat RA-2.data are compared with the daily observations of in situ water *** average absolute observation difference between the"altimeter station"and its nearest gauge station is 0.307 m,which is comparable to the average differences among the gauge *** results suggest that the derived water surface heights from the altimeter data have a good accuracy,which can be used along with the in situ observations as supplements to fill the ungauged area in Poyang lake wetlands.

关键词： Satellite altimetry Wetland hydrology Poyang lake

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