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BRILL-NOETHER MATRIX FOR RANK TWO VECTOR BUNDLES

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Chinese Annals of Mathematics,Series B 2002年第4期23卷 531-538页

作者： TAN XIAOJIANGschool of mathematical sciences, Peking university, Beijing 100871, china school of mathematical sciences Peking University Beijing 100871 China

Let X be an arbitrary smooth irreducible complex projective curve, E (?)X a rank two vector bundle generated by its sections. The author first represents ?as a triple {D1,D2,f}, where D1 , D2 are two effective divisors with d = deg(D1) + deg(D2), and f ∈ H?X, [D1] |D2) is a. collection of polynomials. E is the extension of [D2] by [D1] which is determined by f. By using / and the Brill-Noether matrix of D1+D2, the author constructs a 2g × d matrix WE whose zero space gives Im{H0(X,[D1]) (?) H0(X, [D1] |D1)}(?) Im{H?X, E) (?) H0(X,[D2]) (?) H0(X, [D2]|D2)} From this and H0(X,E) = H0(X,[D1]) (?)Im{H0(X,E) (?) H0(X, [D2])}, it is got in particular that dimH0(X, E) = deg(E) - rank(WE) + 2.

关键词： Brill-Noether matrix Vector bundle Effective divisor

Raising approximation order of refinable vector by increasing multiplicity

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Science china Mathematics 2006年第1期49卷 86-97页

作者： YANG Shouzhi & PENG Lizhong Department of Mathematics, Shantou university, Shantou 515063, china LMAM, school of mathematical sciences, Peking university, Beijing 100871, china Department of Mathematics Shantou University Shantou 515063 China LMAM School of Mathematical Sciences Peking University Beijing 100871 China

An algorithm is presented for raising an approximation order of any given orthogonal multiscaling function with the dilation factor a. Let φ(x) = [φ1(x),φ2(x),…,φr(x)]T be an orthogonal multiscaling function with the dilation factor a and the approximation order m. We can construct a new orthogonal multiscaling function φnew(x) = [ φT(x). f3r+1(x),φr+2(x),…,φr+s(x)}T with the approximation order m + L(L ∈ Z+). In other words, we raise the approximation order of multiscaling function φ(x) by increasing its multiplicity. In addition, we discuss an especial setting. That is, if given an orthogonal multiscaling function φ(x) = [φ1 (x), φ2(x), …, φr(x)]T is symmetric, then the new orthogonal multiscaling function φnew(x) not only raise the approximation order but also preserve symmetry. Finally, some examples are given.

关键词： orthogonal, multiscaling functions, approximation order, symmetry.

Effects of Current Frequency on the Microstructure and Wear Resistance of Ceramic Coatings Embedded with SiC Nano-particles Produced by Micro-arc Oxidation on AZ91D Magnesium Alloy

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Journal of Materials Science & Technology 2010年第10期26卷 865-871页

作者： Yue Yang and Hua Wu Key Laboratory of Advanced Structural Materials,Ministry of Education,changchun university of Technology,changchun 130012.china [a] Key Laboratory of Advanced Structural Materials Ministry of Education changchun university of Technology changchun 130012 china

To improve the surface wear resistance of the ceramic coating fabricated by micro-arc oxidation （MAO） on AZ91D magnesium alloy,ceramic coatings embedded with SiC nano-particles at different current frequency （500 Hz,700 Hz,and 900 Hz） were produced during the MAO *** morphology and phase composition of the coatings were investigated by scanning electron microscopy （SEM）,field emission scanning electron microscopy （FESEM）,and X-ray diffraction （XRD）.The surface roughness of the coatings was characterized by confocal laser scanning microscopy （CLSM）.Simultaneously,the tribological properties of the composite coatings were evaluated by using a universal materials tester （UMT）.The results shows that the wear resistance of the ceramic coatings with SiC nano-particles was improved significantly compared to the ceramic coatings without SiC ***,the composite coating formed at current frequency 900 Hz showed the better wear resistance than the others.

关键词： Magnesium alloy Micro-arc oxidation SiC nano-particles Wear resistance

Totally geodesic submanifolds of maximal rank in symmetric spaces

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Science china Mathematics 2004年第2期47卷 264-271页

作者： ZHU Fuhai & LIANG Keschool of mathematical sciences and LMAM, Peking university, Beijing 100871, china College of mathematical sciences and LPMC, Nankai university, Tianjin 300071, china 1.school of mathematical sciences and LMAM Peking University 100871 Beijing China 2.College of Mathematical Sciences and LPMC Nankai University 300071 Tianjin China

We gave a complete list of totally geodesic submanifolds of maximal rank in symmetric spaces of noncompact type. The compact cases can be obtained by the duality.

关键词： totally geodesic submanifold, Lie triple system, maximal rank.

Micromagnetic Simulation of Demagnetization Curves for Single-Phase Nanocrystalline Nd-Fe-B Magnet

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Journal of Materials Science & Technology 2000年第2期16卷 107-108页

作者： Hanmin JIN, Sufen ZHAO and Xuefeng WANG (Department of Physics, Jinn university, changchun 130012. china) Department of Physics Jilin University Changchun 130012 China

The demangetization curves for the nanocrystalline Nd-Fe-B magnets of the stoichiometric composition were calculated by using the finite element technique of micromagnetism. The curve, especially iHc become smaller with increase of *** most small iHc from a series of the curves along different field directions is closer to that for N=∞. iHc increases with increase of L, and are close cr some what smaller than that the experimental values should be.

关键词： Simulation Nd Fe

NUMERICAL COMPUTATION OF BOUNDED SOLUTIONS FORA SEMILINEAR ELLIPTIC EQUATION ON AN INFINITE STRIP

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Journal of Computational Mathematics 1999年第2期17卷 159-170页

作者： Fu-ming Ma(Department of Mathematics, jilin ’university, changchun 130023, china) 吉林大学数学系吉林长春

In this paper, we consider the computation of bounded solutions of a semilinear elliptic equation on an infinite strip. The dynamical system approach and reduction on center manifold are used to overcome the difficult... 详细信息

关键词： numerical method nonlinear PDE center manifold

ISOTROPIC YIELD BEHAVIORS OF BCC AND FCC METALS

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Acta Metallurgica Sinica(English Letters) 1992年第5期5卷 358-361页

作者： CHEN Jiwei LIAN Jianshe jilin university of Technology,changchun,china jilin Univ of Technology Changchun China

Isotropic yield surfaces of bcc and fec metals have been simulated with TBH *** the five-dimensional stress space proposed recently by Lequeu et al.,the yield subsurfaces on any two of the three shear stresses can be considered as the inscribed circles of their corresponding subsurfaces on n *** on this concept,Hershey,Hosford and Hill (HHH) yield func- tion has been transformed into the formula where the parameters are uniquely determined by two crystallographic factors:the mean Taylor factor in plane strain (M_p) and the critical shear stress (τ_) on slip systems.

关键词： Polycrystalline plasticity yieldfunction cubic metals

INSTANTANEOUS SHRINKING AND LOCALIZATION OF FUNCTIONS IN Y_λ(m,p,q,N) AND THEIR APPLICATIONS

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Chinese Annals of Mathematics,Series B 2001年第3期22卷 361-380页

作者： YUAN HONGJUN Institute of Mathematics, jilin university, changchun 130023, china. Institute of Mathematics Jilin University Changchun 130023 China

The aim of this paper is to discuss the instantaneous shrinking and localization of the support of functions in Yλ(m,p,q,N) and their applications to some nonlinear parabolic equations including the porous medium equation ut = △um-uq, m > 0, q > 0 and the p-Laplace equation ut = div(|△u|p-2△u)-uq, P > 1, q > 0. In particular, as an application of the results, the necessary and sufficient condition for the solutious of the above p-Laplace equation with nonnegative finite Borel measures as initial conditions to have the instantaneous shrinking property of the support is obtained. This is an answer to an open problem posed by R. Kersner and A. Shishkov.

关键词： Porous medium equation p-Laplace equation Instantaneous shrinking Localization property Support

Choice of Parameters in Morse Potential for Copper

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Journal of Materials Science & Technology 1996年第6期12卷 473-475页

作者： Yuming WANG (Dept. of Materials Science, jilin university changchun 130023, china) Dept. of Materials Science Juin University Changchun 130023 China

The choice of parameters in Morse potential for copper was made by the molecular dynamics modeling. The elastic coefficients C-11, C-44, their temperature coefficients T-C11, T-C44, well as the hydrostatic compression behaviour, i.e. pressure/volume curves have been calculated. The choice of Morse potential parameters can be made by comparing the results with the experimental data. The chosen parameters are greatly different for different simulated properties.

关键词： Copper