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EIT waves and coronal magnetic field diagnostics

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Science china(Physics,Mechanics & Astronomy) 2009年第11期52卷 1785-1789页

作者： CHEN PengFei department of Astronomy, nanjing university, nanjing 210093, china 1. department of Astronomy Nanjing University Nanjing 210093 China

Magnetic field in the solar lower atmosphere can be measured by the use of the Zeeman and Hanle effects. By contrast, the coronal magnetic field well above the solar surface, which directly controls various eruptive phenomena, can not be precisely measured with the traditional techniques. Several attempts are being made to probe the coronal magnetic field, such as force-free extrapolation based on the photospheric magnetograms, gyroresonance radio emissions, and coronal seismology based on MHD waves in the corona. Compared to the waves trapped in the localized coronal loops, EIT waves are the only global-scale wave phenomenon, and thus are the ideal tool for the coronal global seismology. In this paper, we review the observations and modelings of EIT waves, and illustrate how they can be applied to probe the global magnetic field in the corona.

关键词： coronal mass ejections (CMEs) magnetic field diagnostics magnetohydrodynamics (MHD)

GLOBAL CONVERGENCE AND IMPLEMENTATION OF NGTN METHOD FOR SOLVING LARGE-SCALE SMARSE NONLINEAR PROGRAMMING PROBLEMS

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Journal of Computational mathematics 2001年第4期19卷 337-346页

作者： Qin Ni (department of mathematics, nanjing university of Aeronautics and Astronautics, nanjing 210016, china) 南京航空航天大学江苏南京 210016

An NGTN method was proposed for solving large-scale sparse nonlinear programming (NLP) problems. This is a hybrid method of a truncated Newton direction and a modified negative gradient direction, which is suitable for handling sparse data structure and pos sesses Q-quadratic convergence rate. The global convergence of this new method is proved, the convergence rate is further analysed, and the detailed implementation is discussed in this paper. Some numerical tests for solving truss optimization and large sparse problems are reported. The theoretical and numerical results show that the new method is efficient for solving large-scale sparse NLP problems.

关键词： Nonlinear programming Large-scale problem Sparse.

Global dimension and left derived functors of Hom

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Science china mathematics 2007年第6期50卷 887-898页

作者： Li-xin MAO & Nan-qing DING Institute of mathematics, nanjing Institute of Technology, nanjing 211167, china department of mathematics, nanjing university, nanjing 210093, china 1. Institute of mathematics Nanjing Institute of Technology Nanjing 211167 China 2. department of mathematics Nanjing University Nanjing 210093 China

It is well known that the right global dimension of a ring R is usually computed by the right derived functors of Hom and the left projective resolutions of right R-modules. In this paper, for a left coherent and right perfect ring R, we characterize the right global dimension of R, from another point of view, using the left derived functors of Hom and the right projective resolutions of right R-modules. It is shown that rD(R) ? n (n ? 2) if and only if the gl right Proj-dim M R ? n?2 if and only if Ext n?1(N,M) = 0 for all right R-modules N and M if and only if every (n?2)th Projcosyzygy of a right R-module has a projective envelope with the unique mapping property. It is also proved that rD(R) ? n (n ? 1) if and only if every (n?1)th Proj-cosyzygy of a right R-module has an epic projective envelope if and only if every nth Proj-cosyzygy of a right R-module is projective. As corollaries, the right hereditary rings and the rings R with rD(R) ? 2 are characterized.

关键词： global dimension projective resolution envelope 16E10 16E30 16E05

Existence of Invariant Tori for Certain Weakly Reversible Mappings

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Acta Mathematica Sinica,English Series 2002年第4期18卷 701-718页

作者： Bao She WEI department of mathematics, nanjing university. nanjing 210093. P. R. china department of mathematics Nanjing University Nanjing 210093 P. R. China

In this paper, we consider certain mappings. M, sufficiently close to an integrable one, which is weakly reversible with respect to the mappings G sufficiently close to an involution of type (m.n). where m, n∈Z_+ are arbitrary. Under some weak non-degeneracy condition, we construct a uniform KAM iteration for proving the existence of a Cantor family of m-tori invariant under the reversible mappings M and the reversing mapping G.

关键词： Weakly reversible mappings Weakly undegenerate condition Invariant tori

A COLUMN RECURRENCE ALGORITHM FOR SOLVING LINEAR LEAST SQUARES PROBLEM

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Journal of Computational mathematics 1996年第4期14卷 301-310页

作者： J.X. Zhao(department of mathematics, nanjing university, nanjing china) nanjing UNIV DEPT MATHNANJING 210008PEOPLES R CHINA

A new column recurrence algorithm based on the classical Greville method and modified Huang update is proposed for computing generalized inverse matrix and least squares solution. The numerical results have shown the ... 详细信息

关键词： Math A COLUMN RECURRENCE ALGORITHM FOR SOLVING LINEAR LEAST SQUARES PROBLEM ABS

ABSOLUTELY E-PURE MODULES AND E-PURE SPLIT MODULES

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Acta Mathematica Scientia 2011年第1期31卷 207-220页

作者：阎舫宇 department of mathematics Nanjing University department of Basic Courses China Pharmaceutical University

We first introduce the concepts of absolutely E-pure modules and E-pure split modules. Then, we characterize the IF rings in terms of absolutely E-pure modules. The E-pure split modules are also characterized.

关键词： Absolutely E-pure module E-pure split module IF ring copure flat module

LIMIT CYCLES AND BIFURCATION CURVES FOR THE QUADRATIC DIFFERENTIAL SYSTEM (III)_(m=0) HAVING THREE ANTI-SADDLES (I)

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Chinese Annals of mathematics,Series B 1996年第2期17卷 167-174页

作者： YE YANQIAN department of mathematics, nanjing university, nanjing 210008, china. 南京大学数学系江苏南京

For the quadratic system: x=-y+δx + lx2 + ny2, y=x(1+ax-y) under conditions -10 the author draws in the (a, ()) parameter plane the global bifurcationdiagram of trajectories around O(0,0). Notice that when na2+l < 0 ... 详细信息

关键词： Quadrtic systen Anti-saddle Bifurcation curve Limit cycle

Lipschitz classes on local fields

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Science china mathematics 2007年第7期50卷 1005-1014页

作者： Wei-yi SU~(1+) Guo-xiang CHEN~2 1 department of mathematics,nanjing university,nanjing 210093,china 2 department of mathematics,nanjing Audit university,nanjing 211815,china 1. department of mathematics Nanjing University Nanjing 210093 China 2. department of mathematics Nanjing Audit University Nanjing 211815 China

The Lipschitz class Lipαon a local field K is defined in this note,and the equivalent relationship between the Lipschitz class Lipαand the Holder type space C~α(K)is ***,those important characteristics on the Euclidean space R^n and the local field K are compared,so that one may interpret the essential differences between the analyses on R^n and ***,the Cantor type fractal functionθ(x)is showed in the Lipschitz class Lip(m,K),m＜(ln 2/ln 3).

关键词： local field Holder type space Lipschitz class Cantor type fractal function 11F85 46F05 43A25 28A80 28A78

A MODIFIED PROJECTION AND CONTRACTION METHOD FOR A CLASS OF LINEAR COMPLEMENTARITY PROBLEMS

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Journal of Computational mathematics 1996年第1期14卷 54-63页

作者： B.S. He(department of mathematics, nanjing university, nanjing, china) nanjing UNIV DEPT MATHNANJING 210008PEOPLES R CHINA

Recently, we have proposed an iterative projection and contraction (PC) method for a class of linear complementarity problems (LCP)([4]). The method was showed to be globally convergent, but no statement could be made about the rate of convergence. In this paper, we develop a modified globally linearly convergent PC method for linear complementarity problems. Both the method and the convergence proofs are very simple. The method can also be used to solve some linear variational inequalities. Several computational experiments are presented to indicate that the method is surprising good for solving some known difficult problems.

关键词： Th Pn A MODIFIED PROJECTION AND CONTRACTION METHOD FOR A CLASS OF LINEAR COMPLEMENTARITY PROBLEMS II