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A tentative study for the prediction of the CME related geomagnetic storm intensity and its transit time

science china(Technological sciences) 2005年第6期48卷 648-668页

作者： ZHAO Xinhua1,2.& FENG Xueshang1,3.1. sIGMA Weather Group, Key Laboratory of space Weather, Center for space science and Applied Re-search, Chinese academy of sciences, beijing 100080,{2. 2. Graduate school of the Chinese academy of sciences, beijing 10003.,{2. 3. school of Geophysics and Geoinformation systems,{2. University of Geosciences, beijing 100083.{2. sIGMA Weather Group Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China Graduate school of the Chinese academy of sciences Beijing China school of Geophysics and Geoinformation systems China University of Geosciences Beijing China

Using 80 CME-ICME events during 1997.1―2.02.9, based on the eruptive source locations of CMEs and solar magnetic field observation at the photosphere, a current sheet magnetic coordinate (CMC) system is established in order to study the propagation of CME and its geoeffectiveness. In context of this coordinate system, the effect of the eruptive source location and the form of heliospheric current sheet (HCs) at the eruptive time of CME on the geomagnetic storm intensity caused by CME and the CME’s transit time at the Earth is investigated in detail. Our preliminary conclusions are: 1) The geomagnetic disturbances caused by CMEs tend to have the so-called “same side-opposite side effect”, i.e. CMEs erupt from the same side of the HCs as the earth would be more likely to arrive at the earth and the geomagnetic disturbances associated with them tend to be of larger magnitude, while CMEs erupting from the opposite side would arrive at the earth with less probability and the corresponding geomagnetic disturbance magnitudes would be relatively weaker. 2. The angular separation between the earth and the HCs affect the corresponding disturbance intensity. That is, when our earth is located near the HCs, adverse space weather events occur most probably. 3. The erupting location of the CME and its nearby form of HCs will also affect its arrival time at the earth. According to these conclusions, in this context of CMC coordinate we arrive at new prediction method for estimating the geomagnetic storm intensity (Dstmin) caused by CMEs and their transit times. The application of the empirical model for 80 CME-ICME events shows that the relative error of Dst is within 3.% for 59% events with Dstmin≤?50 nT, while the averaged absolute error of transit time is lower than 10 h for all events.

关键词： coronal mass ejections, current sheet magnetic coordinate system, geomagnetic storm intensity, transit time, prediction method.

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BOUNDARY FEEDBACK sTABILIZATION OF NONUNIFORM TIMOsHENKO BEAM WITH A TIPLOAD

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Chinese Annals of mathematics,series B 2001年第4期22卷 485-494页

作者： YAN QINGXU, FENG DEXING Institute of systems science, academy of {2. and systems science, Chinese academy of sciences, beijing 100080, china. Institute of systems science, academy of {2. and systems science, Chinese academy of sciences, Be Institute of systems science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China

The boundary stabilization problem of a Timoshenko beam attached with a mass at one end is studied. First, with linear boundary force feedback and moment control simultaneously at the end attached with the load, the energy corresponding to the closed loop system is proven to be exponentially convergent to zero as time t →∞. Then, some counterexamples are given to show that, in other casest the corresponding closed loop system is, in general, not stable asymtotically, let alone exponentially.

关键词： Timoshenko beam Boundary feedback control C0 semigroups Exponential stability Multiplier method

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Affine bracket algebra theory and algorithms and their applications in mechanical theorem proving

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science china mathematics 2007年第7期50卷 941-950页

作者： Ning ZHANG~(1+) Hong-bo LI~2.1 china Institute for Actuarial science (CIAs),Central University of Finance and Economics,beijing 100081,{2. 2.academy of mathematics and systems science,Chinese academy sciences,beijing 100080,{2. china Institute for Actuarial science (CIAs) Central University of Finance and Economics Beijing China academy of mathematics and {2. science Chinese Academy Sciences Beijing China

This paper discusses two problems:one is some important theories and algorithms of affine bracket algebra;the other is about their applications in mechanical theorem *** we give some efficient algorithms including the boundary expanding algorithm which is a key feature in *** analyze the characteristics of the boundary operator and this is the base for the implementation of the *** also give some new theories or methods about the exact division,the representations and structure of affine geometry and so *** practice,we implement the mechanical auto-proving system in Maple 10 based on the above algorithms and *** we test about more than 100 examples and compare the results with the methods before.

关键词： mechanical theorem proving geometric invariance bracket algebra affine geometry affine bracket algebra 68T15 03.3.

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sYMPLECTIC COMPUTATION OF HAMILTONIAN systems (I)

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Journal of Computational mathematics 2002年第3期20卷 267-276页

作者： Yi-fa Tang(LsEC,ICMsEC,academy of mathematics and system sciences, Chinese academy of sciences,{3. 100080, china) 中科院数学与系统科学院 LSEC ICMSEC CAS 北京 100080

Presents information on a study which discussed a symplectic computation of hamiltonian systems. Terms of formal energy of mid-point rule; Analysis of the mathematical pendulum to test the convergence of the formal en... 详细信息

关键词： mid-point rule formal energy

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Monomial Hopf algebras over fields of positive characteristic

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science china mathematics 2006年第3期49卷 320-329页

作者： LIU Gongxiang & YE Yu Institute of mathematics, academy of mathematics and {3. science, Chinese academy of sciences, beijing 100080, china Department of mathematics, University of science and Technology of china, Hefei 2.002., china Institute of mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China Department of mathematics University of Science and Technology of China Hefei China

In this paper, we study the structures of monomial Hopf algebras over a field of positive characteristic. A necessary and sufficient condition for the monomial coalgebra Cd(n) to admit Hopf structures is given here, and if it is the case, all graded Hopf structures on Cd(n)are completely classified. Moreover, we construct a Hopf algebras filtration on Cd(n) which will help us to discuss a conjecture posed by Andruskiewitsch and schneider. Finally combined with a theorem by Montgomery, we give the structure theorem for all monomial Hopf algebras.

关键词： monomial coalgebra, Gaussian binomial coefficient, monomial Hopf algebra.

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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 2.0100,{3. 2.Key Laboratory of {2. and Control, academy of mathematics and {2. science, Chinese academy of sciences, beijing 100190,{3. 3.school of mathematics, sichuan University, Chengdu 610064,{3. school of mathematics Shandong University Jinan China Key Laboratory of systems and Control Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China school of mathematics Sichuan University Chengdu 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

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A note on noncommutative moment problems

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science china mathematics 2005年第8期48卷 1144-1151页

作者： MA Xiujuan school of sciences, Hebei University of Technology, Tianjin 3.013., china mathematics Institute, {2. of mathematics and systems science, Chinese {2. of sciences, beijing 100080, china school of sciences Hebei University of Technology Tianjin China mathematics Institute Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China

Noncommutative moment problems for C*-algebras are studied. We generalize a result of Hadwin on tracial states to nontracial case. Our results are applied to obtain simple solutions to moment problems on the square and the circle as well as extend the positive unital functionals from a (discrete) complex group algebra to states on the group C*-algebra.

关键词： moment, free product, state, group C*-algebra.

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Admissibilities of linear estimator in a class of linear models with a multivariate t error variable

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science china mathematics 2010年第8期53卷 2011-2019页

作者： YANG GuoQing 1 & WU QiGuang 2.1 Department of mathematics,Tongji University,shanghai 2.0092.china 2.Institute of {2. science,academy of mathematics and {2. science,Chinese academy of sciences,beijing 100190,china Department of mathematics Tongji University Shanghai China Institute of systems science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China

This paper discusses admissibilities of estimators in a class of linear models,which include the following common models:the univariate and multivariate linear models,the growth curve model,the extended growth curve model,the seemingly unrelated regression equations,the variance components model,and so *** is proved that admissible estimators of functions of the regression coefficient β in the class of linear models with multivariate t error terms,called as Model II,are also ones in the case that error terms have multivariate normal distribution under a strictly convex loss function or a matrix loss *** is also proved under Model II that the usual estimators of β are admissible for p 2.with a quadratic loss function,and are admissible for any p with a matrix loss function,where p is the dimension of β.

关键词： multivariate t distribution convex loss quadratic loss matrix loss admissible estimator

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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. academy of mathematics and {3. sciences. Chinese academy 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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Note on families of semistable curves over P^1 with 4 singular fibers whose Jacobian are non-compact

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science china mathematics 2010年第7期53卷 1710-1713页

作者： YU Fei 1, 2.1 academy of mathematics and {2. science, Chinese academy of sciences, beijing 100190, china 2.Department of mathematics, East china Normal University, shanghai 2.0062. china academy of mathematics and {2. science Chinese Academy of Sciences Beijing China Department of mathematics East China Normal University Shanghai China

Let f : s → P 1 be a semistable family of curves of genus g 2. We prove that if f admits exactly 5 singular fibers and 4 of them have non-compact Jacobian, then g = 2.

关键词： singular fiber adjoint linear system non-compact Jacobian

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