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Selective Laser Melting Process of Fe-Ni Metal Powder

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稀有金属材料与工程 2011年第S3期40卷 241-244页

作者： Liu Bin, Bai Peikang, Li Yuxin north university of china, taiyuan 030051, china N Univ china Taiyuan 030051 Peoples R China

The density of the SLM forming parts is investigated to determine the good technological parameters of SLM at the same time obtain the dense parts. In the SLM experiment, material used is Fe-Ni metal powder, the good technological parameters of SLM are determined by analyzing the effect of the laser electric current, the laser pulse width, the pulse of laser light frequency, the scan speed, the scan interval, push powder thickness and the scanning way on the single channel scanning, the single-layer scanning, which can lay the foundation for afterward block body formation. Microstructure and properties of the block specimen prepared under the different SLM process parameter are studied by the density measurement and the scanning electronic microscope analysis. The forming parts with high density have been prepared under the optimal SLM process parameters.

关键词： selective laser melting Fe-Ni metal powder density microstructure

ON THE EXISTENCE OF POSITIVESOLUTIONS OF AN ELLIPTICBOUNDARY VALUE PROBLEMON THE EXISTENCE OF POSITIVESOLUTIONS OF AN ELLIPTICBOUNDARY VALUE PROBLEM

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Chinese Annals of mathematics,Series B 2000年第4期21卷 499-510页

作者： LIUZHAOLI LIFUYI departmentofmathematics ShandongUniversityJinan250100China. departmentofmathematics ShanxiUniversityTaiyuan030006China.

Using variational method, the authors get an existence result for positive solutions of a superlinear elliptic boundary value problem without assuming the P.S. condition. To prove the results in this paper, the author... 详细信息

关键词： Superlinear elliptic BVP Positive solution Variational method Gradient flow

ON THE VARIATIONS OF G_2

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Chinese Annals of mathematics,Series B 2003年第3期24卷 387-394页

作者： LIU DONG LIN LEI department of mathematics, East china.Normal university, Shanghai 200062, china. department of mathematics, East china.Normal university, Shanghai 200062, china. department of mathematics East China Normal University Shanghai 200062 China

In [1], Shen Guangyu constructed several classes of new simple Lie algebras of characteristic 2, which are called the variations of G2. In this paper, the authors investigate their derivation algebras. It is shown that G2 and its variations all possess unique nondegenerate associative forms. The authors also find some nonsingular derivations of ViG for i = 3,4, 5, 6, and thereby construct some left-symmetric structures on Vi G for i = 3,4,5,6. Some errors about the variations of sl(3, F) in [1] are corrected.

关键词： Variation Derivation Associative form Left-symmetric structure

THE SECOND EXPONENT SET OF PRIMITIVE DIGRAPHS

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Chinese Annals of mathematics,Series B 2000年第2期21卷 233-236页

作者： MIAO ZHENGKE(department of mathematics, Nanjing university, Nanjing 210093, china.)(department of mathematics, Xuzhou Normal university, Xuzhou 221009, china.) ZHANG KEMIN(department of mathematics, Nanjing university, Nanjing 210093, china.) department of mathematics Nanjing University Nanjing 210093 China department of mathematics Xuzhou Normal University Xuzhou 221009 China

Let D = (V, E) be a primitive digraph. The exponent of D, denoted byγ(D), is the least integer k such that for any u, v∈ V there is a directed walk of length k from u to v. The local exponent of D at a vertex u∈ V, denoted by exp_D (u), is the least integer k such that there is a directed walk of length k from u to v for each v ε V. Let V = {1,2,….,n}. Following [1], the vertices of V are ordered so that exp_D (1) ≤exp_D (2) ≤…≤exp_D(n) =λ(D). Let E_n(i):= {exp_D (i) ∈D PD_n}, where PD_n is the set of all primitive digraphs of order n. It is known that E_n(n) = {γ(D) D∈PD_n} has been completely settled by [7]. In 1998, E_n(1) was characterized by [5]. In this paper, the authors describe E_n(2) for all n≥2.

关键词： Primitive digraph Local exponent Gap

TYPE X MONOTONE SYSTEMS WITH AN ORDER-INCREASING INVARIANT FUNCTION

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Chinese Annals of mathematics,Series B 1996年第3期17卷 335-342页

作者： JIANG JIFA(department of mathematics, The university of Science and Technology of china. Hefei 230036, china.) department of mathematics University of Science and Technology of China Hefei 230036 China

The author considers the asymptotic behavior of solutions of a class of ordinary dmerentialequations x = F(x) in the nonnegative orthant R7. Suppose that F(o) = o, Fi(x1,..., xn) isnondecreasing in xk for all k≠ i and that F possesses an order-increasing invarian *** it is shown that every bounded solution to such a system converges to a single equilibrium.

关键词： Type K monotone system Monotone flow Invariant function Equilibrium Convergence

ON ABELIAN AUTOMORPHISM GROUPS OF SURFACES OF GENERAL TYPE

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Chinese Annals of mathematics,Series B 1996年第1期17卷 43-52页

作者： CAI JINXING(department of mathematics, East china.Normal university, Shanghai 200062, china.) 华东师范大学数学系上海

It is proved that for a complex minimal smooth projective surface S of general type, its abelian automorphism group is of order≤36k2s+24, provided x(os)≥8, where Ks is the canonical divisor of S, and X(Os) the Euler... 详细信息

关键词： Projective surface Automorphism group Canonical divisor

SOME RESULTS ON INFINITE DIMENSIONAL NOVIKOV ALGEBRAS

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Chinese Annals of mathematics,Series B 2003年第3期24卷 309-314页

作者： ZHAO YUFENG MENG DAOJI department of mathematics, Nankai university, Tianjin 300071, china. department of mathematics, Nankai university, Tianjin 300071, china. department of mathematics Nankai University Tianjin 300071

This paper gives some sufficient conditions for determining the simplicity of infinite di-mensional Novikov algebras of characteristic 0, and also constructs a class of simple Novikovalgebras by extending the base fie... 详细信息

关键词： Novikov algebra Novikov-Poisson Algebra Algebraic deformation

ON MULTIPLE POSITIVE SOLUTIONS FOR A NONLINEAR ELLIPTIC PROBLEM IN R^N

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Chinese Annals of mathematics,Series B 2000年第3期21卷 351-358页

作者： YANG HAITAO(department of mathematics, Zhejiang university, HangZhou 310027, china.) WU SHAOPING(department of mathematics, Zhejiang university, HangZhou 310027, china.) department of mathematics Zhejiang University Hangzhou 310027 China

By making use of Variational method, the authors obtain some results about existence of multiple positive solutions and their asymptotic behavior as the parameter →＋∞ for a semilinear elliptic problem in RN.

关键词： Critical point Asymptotic behavior Concentration

ON CLASSIFICATION OF PROJECTIVE VARIETIES WITH NON-INTEGRAL NEF VALUES

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Chinese Annals of mathematics,Series B 2001年第2期22卷 255-262页

作者： ZHAO YICAI department of mathematics, Jinan university, GuangZhou 510632, china. department of mathematics Jinan University Guangzhou 510632 China

Let M be an n-dimensional normal projective variety with only Gorenstein, terminal, Qfactorial singularities. Let L be an ample line bundle on M. Let r denote the nef value of (M, L). The classification of (M, L) via ... 详细信息

关键词： Nef value morphism Ample line bundle Projective variety