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An analysis of the wide area differential method of geostationary orbit satellites

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science china(Physics,Mechanics & Astronomy) 2009年第2期52卷 310-314页

作者： CAI ChengLin1,2,3?, LI XiaoHui1 & WU HaiTao1 1 national Time service center, Chinese Academy of sciences, Lintong 710600, china 2 Hunan Institute of Humanities, science and technology, Loudi 417000, china 3 Graduate university of Chinese Academy of sciences, beijing 100049, china national Time service center Chinese Academy of Sciences Lintong China Hunan Institute of Humanities Science and Technology Loudi China Graduate university of Chinese Academy of sciences Beijing China

This work aims to obtain a wide area differential method for geostationary orbit (GEO) constellation. A comparison between the dilution of precision (DOP) of four-dimensional (4D) calculation including sa- tellite clock errors and ephemeris errors and that of three-dimensional (3D) calculation only including ephemeris errors with the inverse positioning theory of GPS shows the conclusion that all the 3D PDOPs are greatly reduced. Based on this, a basic idea of correcting satellite clock errors and ephem- eris errors apart is put forward, and moreover, a specific method of separation is proposed. Satellite clock errors are separated in a master station with time synchronization, and all the remaining pseu- do-range errors after the satellite clock errors have been deducted are used to work out ephemeris corrections of all GEO satellites. By a comparative analysis of user positioning accuracy before and after differential, the wide area differential method is verified to be quite valid for GEO constellation.

关键词： geostationary orbitsatellite dilution of precision satellite ephemeris errors satellite clock errors wide area differential method

Shell effect and capture cross sections in the synthesis of superheavy nuclei

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science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1489-1493页

作者： DU SaiSai1,2,BIAN BaoAn1,2,3,LIU Min1,2,4,FENG ZhaoQing5,6 & ZHANG FengShou1,2,6 1 Key Laboratory of Beam technology and Material Modification of Ministry of Education,College of Nuclear science and technology,beijing Normal university,beijing 100875,china 2 beijing Radiation center,beijing 100875,china 3 School of science,Jiangnan university,Wuxi 214122,china 4 College of Physics and technology,Guangxi Normal university,Guilin 541004,china 5 Institute of Modern Physics,Chinese Academy of sciences,Lanzhou 730000,china 6 center of Theoretical Nuclear Physics,national Laboratory of Heavy Ion Accelerator of Lanzhou,Lanzhou 730000,china Key Laboratory of Beam technology and Material Modification of Ministry of Education College of Nuclear Science and Technology Beijing Normal University Beijing China beijing Radiation center Beijing China School of science Jiangnan University Wuxi China College of Physics and technology Guangxi Normal University Guilin China Institute of Modern Physics Chinese Academy of Sciences Lanzhou China center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou China

The shell effect is included in the improved isospin dependent quantum molecular dynamics model in which the shell correction energy of the system is calculated by using the deformed two-center shell model. A switch function is introduced to connect the shell correction energy of the projectile and the target with that of the compound nucleus during the dynamical fusion process. It is found that the calculated capture cross sections reproduce the experimental data quantitatively at the energy near the Coulomb barrier. The capture cross sections for reaction 35 80 Br + 82 208 Pb → 117 288 X are also calculated and discussed.

关键词： superheavy nuclei transport theory shell effect cross sections

One-pot synthesis of crystalline SnO_2 nanoparticles and their low-temperature ethanol sensing characteristics

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science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1601-1605页

作者： CHEN YuJin1,2,3,ZHU ChunLing4,WANG LiJiao3 & WANG TaiHong2 1 School of materials science and Engineering,beijing Institute of technology,beijing 100081,china 2 Micro-Nano Technologies Research center,Hunan university,Changsha 410082,china 3 College of science,Harbin Engineering university,Harbin 150001,china 4 College of Material science and Chemical Engineering,Harbin Engineering university,Harbin 150001,china School of materials science and Engineering Beijing Institute of Technology Beijing China Micro-Nano Technologies Research center Hunan University Changsha China College of science Harbin Engineering University Harbin China College of Material science and Chemical Engineering Harbin Engineering University Harbin China

Crystalline SnO2 nanoparticles(NPs) with a diameter less than 6 nm are synthesized using potassium stannate trihydrate as the precursor in a basic *** synthesized NPs can detect ethanol at a ppm level even at 100℃.Furthermore,the NPs have good selectivity to *** excellent ethanol sensing performances are attributed to the small size effect according to the space-charge model.

关键词： SnO2 nanoparticles sensing characteristics

Secure network coding in the presence of eavesdroppers

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science china(Information sciences) 2010年第3期53卷 648-658页

作者： LUO MingXing1,2,3, YANG YiXian1,2,3, WANG LiCheng1,2,3 & NIU XinXin1,2,3 1Information Security center, State Key Laboratory of Networking and Switching technology, beijing university of Posts and Telecommunications, beijing 100876, china 2Key Laboratory of Network and Information Attack and Defence technology of MOE, beijing university of Posts and Telecommunications, beijing 100876, china 3national Engineering Laboratory for Disaster Backup and Recovery, beijing university of Posts and Telecommunications, beijing 100876, china Information Security center State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Key Laboratory of Network and Information Attack and Defence technology of MOE Beijing University of Posts and T

Our concern, in the paper, is to construct information-theoretic secure network coding in the presence of eavesdroppers. Based on the generalized attack model and all-or-nothing transformation, the security of network coding in the generalized combination network can be characterized by the network capacity and the min-cut bound of wiretapping set from the source. Furthermore, it can be extended to any directed acyclic networks with single source. Compared with the traditional results, we construct information-theoretic secure network coding without additional encryptions and giving up any capacity.

关键词： all-or-nothing transformation secure network coding eavesdropping

Complete multiple round quantum dense coding with quantum logical network

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Chinese science Bulletin 2007年第9期52卷 1162-1165页

作者： LI ChunYan1,2,LI XiHan1,2,DENG FuGuo1,2,3,ZHOU Ping1,2 & ZHOU HongYu1,2,3 1 Key Laboratory of Beam technology and Material Modification of Ministry of Education,beijing Normal university,beijing 100875,china 2 Institute of Low Energy Nuclear Physics,and Department of Material science and Engineering,beijing Normal university,beijing 100875,china 3 beijing Radiation center,beijing 100875,china Key Laboratory of Beam technology and Material Modification of Ministry of Education Beijing Normal University Beijing 100875 China

We present a complete multiple round quantum dense coding scheme for improving the source ca-pacity of that introduced recently by Zhang et al. The receiver resorts to two qubits for storing the four local unitary ope... 详细信息

关键词：量子通信多重量子紧凑编码量子逻辑网络量子纠缠

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基于平稳小波变换的相空间重构方法

振动．测试与诊断 2012年第6期32卷 981-985,1038页

作者：章立军张利欣阳建宏黎敏北京科技大学国家材料服役安全科学中心北京100083 北京科技大学机械工程学院北京100083

针对非线性信号特征提取问题,提出一种基于平稳小波变换的相空间重构方法。对信号进行多层平稳小波分解,利用得到的不同尺度小波系数进行相空间重构,通过局部切空间变换方法提取蕴涵在相空间高维数据集中信号的低维形态特征。仿真试验... 详细信息

针对非线性信号特征提取问题,提出一种基于平稳小波变换的相空间重构方法。对信号进行多层平稳小波分解,利用得到的不同尺度小波系数进行相空间重构,通过局部切空间变换方法提取蕴涵在相空间高维数据集中信号的低维形态特征。仿真试验结果表明,非线性信号经过平稳小波变换后,吸引子轨迹与原有轨迹具有相似的结构。利用局部切空间变换可获得带有高斯白噪声的非线性信号的低维形态特征,该低维形态特征与原有非线性信号的吸引子轨迹相似。这种相空间重构方法较传统的方法具有一定的优势,可以用于提取含有噪声的机械振动信号的故障特征。

关键词：非线性平稳小波变换相空间重构降维低维形态特征

Learning interactions among multi-channel sequences with dynamical influence models

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science china(Information sciences) 2010年第7期53卷 1336-1344页

作者： ZHANG WeiDong, CHEN Feng & XU WenLi Department of Automation, national Laboratory for Information science and technology, Tsinghua university, beijing 100084, china Department of Automation National Laboratory for Information Science and Technology Tsinghua University

Many real applications involve simultaneous recording and analysis of multi-channel information sources. Learning and modeling the interactions among channels is the kernel step to analyze and recognize system characteristics. This paper presents a model that learns the dynamical influence among multi-channel sequences. The model, dynamical influence model, permits functional roles of individual channels to change and models the changing influence strength between channels. By querying the values of influence factors, we can recognize the functional role of each channel qualitatively and learn about to what extent the chains influence each other quantitatively at any time. The experimental results on synthetic data and application of multi-person interaction recognition show that our model is reliable and effective.

关键词： multi-channel processing dynamical interaction influence model activity recognition

Connectivity of the Mandelbrot set for the family of renormalization transformations

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science china Mathematics 2010年第3期53卷 849-862页

作者： WANG XiaoGuang 1,QIU WeiYuan 1 , YIN YongCheng 1 , QIAO JianYong 2 & GAO JunYang 2 1 School of Mathematical sciences, Fudan university, Shanghai 200433, china 2 center of Mathematics, china university of Mining and technology, beijing 100083, china School of Mathematical sciences Fudan University

We show that the Mandelbrot set for the family of renormalization transformations of 2-dimensional diamond-like hierachical Potts models in statistical mechanics is connected. We also give an upper bound for the Hausd... 详细信息

关键词： connectivity Mandelbrot set renormalization transformations

BRST quantization and canonical Ward identity of the supersymmetric electromagnetic interaction system

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science china(Physics,Mechanics & Astronomy) 2007年第3期50卷 339-347页

作者： HUANG YongChang1,3,4, JIANG YunGuo1 & LI XinGuo2,3 1 Institute of Theoretical Physics, College of Applied sciences, beijing university of technology, beijing 100022, china 2 Institute of Modern Physics, Chinese Academy of sciences, Lanzhou 730000, china 3 center of Theoretical Nuclear Physics, national Laboratory of Heavy Ion Collisions, Chinese Academy of sciences, Lanzhou 730000, china 4 china center of Advanced science and technology (World Laboratory), beijing 100080, china Institute of Theoretical Physics College of Applied Sciences Beijing University of Technology Beijing China center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Collisions Chinese Academy of Sciences Lanzhou China china center of Advanced science and technology (World Laboratory) Beijing China Institute of Modern Physics Chinese Academy of Sciences Lanzhou China

According to the method of path integral quantization for the canonical constrained system in Becchi-Rouet-Stora-Tyutin scheme, the supersymmetric electromagnetic interaction system was quantized. Both the Hamiltonian of the supersymmetric electromagnetic interaction system in phase space and the quantization procedure were simplified. The BRST generator was constructed, and the BRST transforma- tions of supersymmetric fields were gotten; the effective action was calculated, and the generating functional for the Green function was achieved; also, the gauge generator was constructed, and the gauge transformation of the system was ob- tained. Finally, the Ward-Takahashi identities based on the canonical Noether theorem were calculated, and two relations between proper vertices and propaga- tors were obtained.

关键词： supersymmetric electromagnetic interaction BRST quantization Ward identity