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2-D Frequency Spectrum Features and Error Analysis for Interferometric Passive Microwave Imager

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2-D Frequency Spectrum Features and Error Analysis for Inter...

Uniform design over a convex polyhedron

IEEE 2007 International Symposium on Microwave,Antenna,Propagation and EMC Technologies for Wireless Communications(ISMAPE-2007)

作者： Pan Bei~(1,2)Wu Ji~1 (1.center for space science and applied research,chinese academy of science,P.O.Box 8701,beijing 100080, china 2.Graduate University of chinese academy of sciences,beijing 100039,china

This paper introduces the basic concepts of Interferometric Passive Microwave Imager(Aperture Synthesis Interferometric Radiometers),and presents several features of 2-D frequency *** basis of those features,the directions and positions of baselines with errors can be identified approximately. And the effects caused by several systematic errors (antenna position error,baseline absence,amplitude error and phase error in channels,and antenna pattern error)on the reconstructed images,are analyzed particularly. The analyses in the paper can provide the evidences to identify the error types and sources in Interferometric Passive Microwave Imager,and can supply important references to design enhancement algorithms.

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chinese science Bulletin 1999年第2期44卷 112-114页

作者： FANG Kaitai , TIAN Guoliang XIE Minyu Hong Kong Baptist University, Kowloon, Hong Kong, china Institute of applied Mathematics, chinese academy of sciences, beijing 100080, china Central china Normal University, Wuhan 430070, chinaCorresponding author: Present address: Department of Probability and Statistics, Peking University, beijing 100871, china Hong Kong Baptist University Hong Kong China Institute of applied Mathematics Chinese Academy of Sciences Beijing China Central china Normal University Wuhan China

A new method, called the simplex method, is proposed to generate the uniform design over a convex polyhedron in n-dimensional Euclidean

关键词： convex polyhedron experimental design uniform design.

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卫星网络仿真系统建模的研究

计算机工程与应用 2004年第23期40卷 142-144,208页

作者：王曦爽孟新中国科学院空间科学与应用研究中心北京100080

提出了建立一个卫星网络仿真模型的基本架构,分析了如何构造卫星网络仿真模型的卫星拓扑结构、如何仿真空间环境下卫星网络通信链路、如何表现空间环境特点对卫星网络的影响等问题,并通过对一个小卫星网络与地面终端的通信过程的仿真实... 详细信息

提出了建立一个卫星网络仿真模型的基本架构,分析了如何构造卫星网络仿真模型的卫星拓扑结构、如何仿真空间环境下卫星网络通信链路、如何表现空间环境特点对卫星网络的影响等问题,并通过对一个小卫星网络与地面终端的通信过程的仿真实现验证了架构方案的可靠性。

关键词：卫星网络网络仿真仿真架构 NS 卫星拓扑结构

Hierarchical linear regression models for conditional quantiles

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science china Mathematics 2006年第12期49卷 1800-1815页

作者： TIAN Maozai & CHEN Gemai School of Statistics, Renmin University of china, beijing 100872, china and center for applied Statistics, Renmin University of china, beijing 100872, china Department of Mathematics and Statistics, University of Calgary, Canada School of Statistics Renmin University of China Beijing China center for applied Statistics Renmin University of China Beijing China Department of Mathematics and Statistics University of Calgary Canada

The quantile regression has several useful features and therefore is gradually developing into a comprehensive approach to the statistical analysis of linear and nonlinear response models,but it cannot deal effectively with the data with a hierarchical *** practice,the existence of such data hierarchies is neither accidental nor ignorable,it is a common *** ignore this hierarchical data structure risks overlooking the importance of group effects,and may also render many of the traditional statistical analysis techniques used for studying data relationships *** the other hand,the hierarchical models take a hierarchical data structure into account and have also many applications in statistics,ranging from overdispersion to constructing min-max ***,the hierarchical models are virtually the mean regression,therefore,they cannot be used to characterize the entire conditional distribution of a dependent variable given high-dimensional ***,the estimated coefficient vector (marginal effects)is sensitive to an outlier observation on the dependent *** this article,a new approach,which is based on the Gauss-Seidel iteration and taking a full advantage of the quantile regression and hierarchical models,is *** the theoretical front,we also consider the asymptotic properties of the new method,obtaining the simple conditions for an n1/2-convergence and an asymptotic *** also illustrate the use of the technique with the real educational data which is hierarchical and how the results can be explained.

关键词： hierarchical quantile regression models,EQ algorithm,fixed effects,random effects,regression quantile.

space MATERIALS science

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空间科学学报 1998年第S1期18卷 104-111页

作者： CHEN Wan-chun Wei B.(Institute of Physics, The chinese academy of sciences, beijing 100080)(Department of applied Physics in Northwestern Polytechnical Univerity)

The main studying activities and results on space materials science during 1996-1997 in china were summarized. The typical research subjects are crystal growth from melt, crystal growth from solution, nucleation, undercooling,solidification of alloys and space experimental hardware. They are carried out by the ground-based studies, the short duration microgravity missions and orbital experiments.

关键词： space materials science Crystal growth Solidification Microgravity

A fast onboard star-extraction algorithm optimized for the SVOM Visible Telescope

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science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 51-55页

作者： WANG TianZhou1,2,QIU YuLei1,CAI HongBo1 & DENG JingSong1 1 National Astronomical Observatories,chinese academy of sciences,beijing 100012,china 2 Graduate University of chinese academy of sciences,beijing 100049,china chinese academy of sciences National Astronomical Observatories Beijing China (GRID:grid.9227.e) (ISNI:***) Graduate University of chinese academy of sciences Beijing China (GRID:grid.458514.9) chinese academy of sciences National Astronomical Observatories Beijing China (GRID:grid.9227.e) (ISNI:***)

The space multi-band Variable Object Monitor(SVOM) is a proposed chinese astronomical satellite,dedicated to the detection,localization and measurement of gamma-ray bursts(GRBs) on a cosmological *** efficient algorithm is developed for the purpose of onboard star extraction from the CCD images obtained with the Visible Telescope(VT) onboard the *** CCD pixel coordinates of the reference stars will be used to refine the astronomical position of the satellite,which will facilitate triggering rapid ground-based follow-up observations of the *** this algorithm,the image is divided into a number of grid cells and the "global" pixel-value maximum within each cell is taken as the first-guess position of a "bright" *** correct center position of a star is then computed using a simple iterative *** two additional strategies,i.e.,scanning the image only by even(or odd) lines or in a black-white chess board mode,we propose to further reduce the time to extract the *** examine the efficiency of the above algorithms,we applied them to the experimental images obtained with a ground-based *** find that the accuracy of the astronomical positioning achieved by our method is comparable to that derived by using the conventional star-extraction method,while the former needs about 25 times less CPU time than the *** will significantly improve the performance of the SVOM VT mission.

关键词： gamma-ray burst(GRBs) SVOM VT on board computation

An eSnake model for medical image segmentation

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Progress in Natural science:Materials International 2005年第5期15卷 424-429页

作者： Lv Hongyu1, YUAN Kehong2, BAO Shanglian1, ZU Donglin1 and DUAN Chaijie1*(1. The research center for Tumor Diagnosis and Therapeutical Physics & beijing Key Laboratory of Medical Physics and Engineering, beijing 100871, china 2. Key Laboratory of Pure and applied Mathematics, School of Mathematical sciences, Peking University, beijing 100871, china) The research center for Tumor Diagnosis and Therapeutical Physics & beijing Key Laboratory of Medical Physics and Engineering Beijing 100871 China Key Laboratory of Pure and applied Mathematics School of Mathematical Sciences Peking University Beijing 100871 China

A novel scheme of external force for detecting the object boundary of medical image based on Snakes (active contours) is introduced in the paper. In our new method, an electrostatic field on a template plane above the original image plane is designed to form the map of the external force. Compared with the method of Gradient Vector Flow (GVF), our approach has clear physical meanings. It has stronger ability to conform to boundary concavities, is simple to implement, and reliable for shape segmenting. Additionally, our method has larger capture range for the external force and is useful for medical image preprocessing in various applications. Finally, by adding the balloon force to the electrostatic field model, our Snake is able to represent long tube-like shapes or shapes with significant protrusions or bifurcations, and it has the specialty to prevent Snake leaking from large gaps on image edge by using a two-stage segmentation technique introduced in this paper. The test of our models proves that our methods are robust, precise in medical image segmentation.

关键词： image segmentation eSnake external force electrostatic field balloon force.

WIND observations of plasma waves inside the magnetic cloud boundary layers

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science Bulletin 2005年第18期 85-90页

作者： WEI Fengsi1 , ZHONG Dingkun1,2, FENG Xueshang1, YANG Fang1,2 & LIU Rui 1 1. SIGMA Weather Group, Laboratory for space Weather, center for space science and applied research, chinese academy of sciences, beijing 100080, china 2. Graduate School, chinese academy of sciences, beijing 100049, china

Based on the WIND observational data for the plasma waves from thermal noise receptor (TNR) working on the frequency 4―256 kHz and the solar wind and the magnetic fields, we analyze the plasma wave activities in the 60 magnetic cloud’s boundary layers (BLs) and find that there are often various plasma wave activities in the BLs, which are different from those in the adjacent solar wind (SW) and the magnetic clouds (MC). The basic characteris-tics are that: (1) the enhancement of the Langmuir wave near the electronic plasma frequency (fpe) is a dominant wave ac-tivity, which occupies 75% investigated samples; (2) the events enhanced both in the langmuir and ion acustic (f space developing space plasma wave theory.

关键词： solar wind magnetic cloud boundary layer plasma waves.

Electromagnetic Simulation of ISAR Imaging with Supper-Resolution

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Electromagnetic Simulation of ISAR Imaging with Supper-Resol...