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Orbit determination for geostationary satellites with the combination of transfer ranging and pseudorange data

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science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1746-1754页

作者： GUO Rui1,2,3.4,HU XiaoGong2,4,LIU Li1,WU XiaoLi1,HUANG Yong2,4 & HE Feng1 1 Beijing Global Information application and Development Center,Beijing 100094,china 2 Shanghai Astronomical Observatory,chinese {3. of sciences,Shanghai 20003.,china 3.Graduate University of chinese academy of sciences,Beijing 100049,china 4 space Navigation and Positioning Technology,Laboratory of Shanghai Municipal,Shanghai 20003.,china 1. Beijing Global Information application and Development Center Beijing 100094 China2. Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China3. Graduate University of Chinese Academy of Sciences Beijing 100049 China4. Space Navigation and Positioning Technology Laboratory of Shanghai Municipal Shanghai 200030 China

Geostationary satellites(GEOs) play a significant role in the regional satellite navigation *** experiments show that the clock corrections could be mitigated through a single strategy or double differencing strategies for a navigation constellation,but for the mode of individual GEO orbit determination,high precision orbit and clock correction could not be obtained in the orbit determination based on the pseudorange data.A new GEO combined precise orbit determination(POD) strategy is studied in this paper,which combines pseudorange data and C-band transfer ranging *** strategy overcomes the deficiency of C-band transfer ranging caused by limited stations and tracking time *** the combination of transfer ranging and pseudorange data,clock corrections between the GEO and the stations can be estimated simultaneously along with orbital parameters,maintaining self-consistency between the satellite ephemeris and clock correction *** error covariance analysis is conducted to illuminate the contributions from the transfer ranging data and the psudoranging *** data collected for a chinese GEO satellite with 3.C-band transfer ranging stations and 4 L-band pseudorange tracking stations,POD experiments indicate that a meter-level accuracy is *** root-mean-square(RMS) of the post-fit C-band ranging data is about 0.203.m,and the RMS of the post-fit pseudorange is 0.408 *** component errors of the POD experiments are independently evaluated with the satellite laser ranging(SLR) data from a station in Beijing,with the residual RMS of 0.076 *** SLR evaluation also suggests that for 2-h orbital predication,the predicted radial error is about 0.404 m,and the clock correction error is about 1.3. *** for the combination of one C-band transfer ranging station and 4 pseudorange stations,POD is able to achieve a reasonable accuracy with the radial error of 0.280 m and the 2-h predicted radial error of 0.888 *** syn

关键词： satellite navigation precise orbit determination pseudorange equipment ranging delay GEO SLR

Lunar ~3.e estimations and related parameters analyses

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science china Earth sciences 2010年第8期53卷 1103-1114页

作者： LI DiHui, LIU HeGuang, ZHANG WeiGuo, LI Yun & XU ChuanDong Center for space science and Applied Research, chinese academy of sciences, Beijing 100190,{3. 1. Center for space science and Applied Research Chinese Academy of Sciences Beijing 100190 China

As a potential nuclear fuel, 3.e element is significant for both the solution of impending human energy crisis and the conservation of natural environment. Lunar regolith contains abundant and easily extracted 3.e. Based on the analyses of the impact factors of 3.e abundance, here we have compared a few key assessment parameters and approaches used in lunar regolith 3.e reserve estimation and some representative estimation results, and discussed the issues concerned in 3.e abundance variation and 3.e reserve estimation. Our studies suggest that in a range of at least meters deep, 3.e abundance in lunar regolith is homogeneously distributed and generally does not depend on the depth; lunar regolith has long been in a saturation state of 3.e trapped by minerals through chemical bonds, and the temperature fluctuation on the lunar surface exerts little influence on the lattice 3.e abundance. In terms of above conclusions and the newest lunar regolith depth data from the microwave brightness temperature retrieval of the "ChangE-1" Lunar Microwave Sounder, a new 3.e reserve estimation has been presented.

关键词： lunar regolith 3.e abundance reserve estimation maturity granularity composition solar wind flux CELMS

The Multifractal Analysis of the Occupation Measure of a Lévy Process

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Wuhan University Journal of Natural sciences 2000年第3期5卷 253-256页

作者： Hu Xiao\|yu Institute of Applied Mathematics, chinese academy of sciences, Beijing 100080, china chinese academy of sciences Institute of Applied Mathematics Beijing China (GRID:grid.9227.e) (ISNI:***)

We introduce the results on the multifractal structure of the occupation measures of a Brownian Motion, a stable process, a general subordinator and a stochastic process derived from random reordering of the Cantor se... 详细信息

关键词： occupation measure Levy process Brownian motion stable process subordinator

Research on applying physical chaos generator to spacecraft information security

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science china(Technological sciences) 2009年第5期52卷 1463-1470页

作者： ZHAO HePing State Key Laboratory of Information Security,Graduate University of chinese academy of sciences,Beijing 100049,china china {3. of space Technology,Beijing 100094,china State Key Laboratory of Information Security Graduate University of Chinese Academy of Sciences Beijing 100049 China china academy of space Technology Beijing 100094 China

The effectiveness of a short-length message extension method based on physical chaos generator was analyzed and the entropy of the extended message was calculated in this *** analysis demon-strated that with the mentioned method the entropy of short-length messages,which are repeatedly used in spacecraft data systems,is obviously increased,and the security of transmission is enhanced as *** paper also presented an improvement of the protocol for secret key agreement presented by *** and *** of depending on characteristics of communication channel,this method takes advantage of the random data produced by physical chaos generator to preset the initial parameters of the procedure on both sides of communication,so that the procedure and quantity of cipher key can be precisely *** method can be used to cipher key management of se-cure communication between long life-span spacecraft and ground system.

关键词： physical chaos generator spacecraft information security message extension cipher key management

Holomorphic invariant forms of a bounded domain

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science china Mathematics 2008年第11期51卷 1945-1964页

作者： LU QiKeng Institute of Mathematics, academy of Mathematics and Systems science, chinese academy of sciences, Beijing 100190,{3. Institute of Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

Given a complete ortho-normal system ? = (?0,?1,?2,…) of L 2 H( $ \mathcal{D} $ ), the space of holomorphic and absolutely square integrable functions in the bounded domain $ \mathcal{D} $ of ? n , we construct a holomorphic imbedding $ \iota _\phi :\mathcal{D} \to \mathfrak{F}(n,\infty ) $ , the complex infinite dimensional Grassmann manifold of rank n. It is known that in $ \mathfrak{F}(n,\infty ) $ there are n closed (μ, μ)-forms τμ (μ = 1,…,n) which are invariant under the holomorphic isometric automorphism of $ \mathfrak{F}(n,\infty ) $ and generate algebraically all the harmonic differential forms of $ \mathfrak{F}(n,\infty ) $ . So we obtain in $ \mathcal{D} $ a set of (μ, μ)-forms ι ? * τμ (μ = 1,…, n), which are independent of the system ? chosen and are invariant under the bi-holomorphic transformations of $ \mathcal{D} $ . Especially the differential metric ds 2 1 associated to the K?hler form ι ? * τ1 is a K?hler metric which differs from the Bergman metric ds 2 of $ \mathcal{D} $ in general, but in case that the Bergman metric is an Einstein metric, ds 1 2 differs from ds 2 only by a positive constant factor.

关键词： complete ortho-normal system holomorphic invariant forms 3.A3. 3.A65

Range inclusion of operators on non-archimedean Banach space

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science china Mathematics 2010年第12期53卷 3215-3224页

作者： WANG PengHui 1 & ZHANG Xu 2,3.1 School of Mathematics, Shandong University, Jinan 250100, china 2 Key Laboratory of Systems and Control, academy of Mathematics and Systems science,{3., Beijing 100190, china 3.School of Mathematics, Sichuan University, Chengdu 610064, china 1. School of Mathematics Shandong University Jinan 250100 China2. Key Laboratory of Systems and Control Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China3. School of Mathematics Sichuan University Chengdu 610064 China

In this paper, we establish some range inclusion theorems for non-archimedean Banach spaces over general valued fields. These theorems provide close relationship among range inclusion, majorization and factorization for bounded linear operators. It is found that these results depend strongly on a continuous extension property, which is always true in the classical archimedean case, but may fail to hold for the non-archimedean setting. Several counterexamples are given to show that our results are sharp in some sense.

关键词： range inclusion majorization factorization non-archimedean Banach space continuous extension property

Electron dynamics in collisionless magnetic reconnection with a PIC simulation

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chinese science Bulletin 2009年第3期54卷 456-460页

作者： GUO Jun1,2 1 School of Mathematics and Physics, Qingdao University of science and Technology, Qingdao 266042, china 2 State Key Laboratory of space Weather,{3., Beijing 100080, china School of Mathematics and Physics Qingdao University of Science and Technology Qingdao China State Key Laboratory of space Weather Chinese Academy of Sciences Beijing China

Two-dimensional particle-in-cell (PIC) simulation is used to investigate electron dynamics in colli- sionless magnetic reconnection, and the proton/electron mass ratio is taken to be mi /me = 256. The results show that the presence of a strong initial guide field will change the direction of the electron flow. The electron density cavities and the parallel electric field can be found in the electron inflow re- gion along the separatrix, and the electron inflow and density cavities only appear in the second and fourth quadrants. What is different from the results with a smaller mass ratio is that new structures appear in the diffusion region near the X line: (1) Narrow regions of density enhancement and density cavities can be found synchronously in this region; and (2) corresponding to the electron density changes near the X line, the strong parallel electric fields are found to occur in the first and third quadrants. These electric fields perhaps play a more important role in acceleration and heating electrons than those fields located in the density cavities.

关键词： PIC模仿磁链接导向场电子动力学

ON LIMITATIONS OF THE SAMPLED-DATA FEEDBACK FOR NONPARAMETRIC DYNAMICAL SYSTEMS

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Journal of Systems science & Complexity 2002年第3期15卷 225-250页

作者： XUE Feng QUO Lei (Institute of Systems science, chinese academy of sciences, Beijing 100080,{3.) Institute of Systems science Chinese Academy of Sciences 北京 100080

In this paper, we study a basic class of first order sampled-data control systems with unknown nonlinear structure and with sampling rate not necessarily fast enough, aiming at understanding the capability and limitations of the sampled-data feedback. We show that if the unknown nonlinear function has a linear growth rate with its 'slope' (denoted by L) being a measure of the 'size' of uncertainty, then the sampling rate should not exceed 1/L multiplied by a constant (≈ 7.53. for the system to be globally stabilizable by the sampled-data feedback. If, however, the unknown nonlinear function has a growth rate faster than linear, and if the system is disturbed by noises modeled as the standard Brownian motion, then an example is given, showing that the corresponding sampled-data system is not stabilizable by the sampled-data feedback in general, no matter how fast the sampling rate is.

关键词： Sampled-data control adaptive control uncertain nonlinear systems Brow-nian motion stability.

Low-frequency fluctuations in the magnetosheath: Double Star TC-1 and Cluster observations

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science china(Technological sciences) 2008年第10期51卷 1626-1638页

作者： DU Jian1,2 WANG Chi1, SONG Pu3.4 & ZHANG TieLong5 1 State Key Laboratory of space Weather, Center for space science and Applied Research,{3., Beijing 100190, china 2 Graduate School,{3., Beijing 100049, china 3.Earth, Environmental and Atmospheric sciences Department, University of Massachusetts, Lowell, Mas-sachusetts MA 01854, USA 4 Center for Atmospheric Research, University of Massachusetts, Lowell, Massachusetts MA 01854, USA 5 space Research Institute, Austrian academy of sciences, Graz A-8010, Austria State Key Laboratory of space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100190 China Graduate School Chinese Academy of Sciences Beijing 100049 China Earth Environmental and Atmospheric Sciences Department University of Massachusetts Lowell Massachusetts MA 01854 USA Center for Atmospheric Research University of Massachusetts Lowell Massachusetts MA 01854 USA space Research Institute Austrian Academy of Sciences Graz A-8010 Austria

The magnetic field variations are analyzed in the range of time periods from 4 s to 240 s in the magnetosheath observed by the Double Star TC-1 and Cluster in 2004. The characteristics of the magnetic field fluctuations are strongly controlled by the angle between the upstream interplanetary magnetic field (IMF) and the normal of the bow shock. generally speaking, the magnetic field fluctuations in the quasi- parallel magnetosheath are more intense than those in the quasi-perpendicular ones. Almost purely compressional waves are found in the quasi-perpendicular magnetosheath. With the increase of the local plasma β, both the magnitude and direction of the magnetic field fluctuate more intensely. There exists an inverse correlation between the local temperature anisotropy T⊥/T|| and the plasma β.

关键词： low-frequency fluctuations magnetosheath MHD instabilities