关于Riemann流形中的2-调和子流形

讨论了黎曼流形中的 2-调和子流形,获得了这类子流形的第二基本形式模长平方和Ricci曲率的pinching定理:设M是n+p维黎曼流形N的具有平行平均曲率向量的n维 2-调和子流形,如果N的截面曲率的上、下确界分别记为KN和KN,则当M的第二基本形式模长平方s[ (n-1)KN-KN+nH2 ]时,M是极小子流形。     

S1^4中的Ⅱ型洛伦兹等参超曲面

研究S1^4中的Ⅱ型洛伦兹等参超曲面。证明了S1^4研中最小多项式为（λ-a）^2的Ⅱ型洛伦兹等参超曲面局部地被两个函数C1（t）和C2（t）所唯一确定，并给出了这种超曲面的解析表达式，从而完成了S1^4中的Ⅱ型洛伦兹等参超曲面的分类。     

TFEL器件亮度波形的快速过程

研究了TFEL亮度波形的上升与衰减过程,发现除一般的直接碰撞激发外,在发光中心的离导带较近的能级跃迁的发光中还存在另一种非常快的发光过程.通过分析ZnS:Er³⁺、Tin³⁺、Ce³⁺+Nd³⁺等不同样品,我们认为这种快过程属于导带中的慢电子与离化了的发光中心的复合.     

一个有限区间逆向的Hilbert型积分不等式

引入多参数,应用分析的方法以估算权函数,在有限区间(a,b)(0相似文献   

Propagation of SH waves in layered functionally gradient piezoelectric–piezomagnetic structures

Abstract

The propagation of SH waves is studied in two bonded semi-infinite material, one piezoelectric and the other piezomagnetic. Both materials are functionally gradient materials. The material properties of the two materials vary in two directions, one parallel to the interface and the other perpendicular to the interface. The dispersion relations are obtained in explicit forms for different forms of the non-homogeneities. The effects of gradient variation about material constants on the frequency of SH waves and on the wave numbers are shown graphically.     

EXACT－VOLUME DIFFERENTIAL FORM DE RHAM COHOMOLOGY AND HAMILTON VARIATIONAL PRINCIPLE

ＥＸＡＣＴ－ＶＯＬＵＭＥＤＩＦＦＥＲＥＮＴＩＡＬＦＯＲＭＤＥＲＨＡＭＣＯＨＯＭＯＬＯＧＹＡＮＤＨＡＭＩＬＴＯＮＶＡＲＩＡＴＩＯＮＡＬＰＲＩＮＣＩＰＬＥＷａｎｇＪｉｃｈｕｎ（王继春）（Ｄｅｐｔ．Ｍａｔｈ．Ｐｈｙｓ．ｏｆＷｕｈａｎＵｎｌｙ．ｏｆＴｅｃｈｎ...     

单位球面上的子流形有关截曲率的Pinching定理

设M是单位球面上不含脐点的子流形,Moebius形式Φ消失,本文讨论M 关于Mobius度量的截曲率的Pinching问题.     

Cut numbers of -manifolds

We investigate the relations between the cut number, and the first Betti number, of -manifolds We prove that the cut number of a ``generic' -manifold is at most This is a rather unexpected result since specific examples of -manifolds with large and are hard to construct. We also prove that for any complex semisimple Lie algebra there exists a -manifold with and Such manifolds can be explicitly constructed.

     

Sharp Estimates for the Size of Balls in the Complement of a Hypersurface

In this paper, we make estimates for the radius of balls contained in some component of the complementary of a complete hypersurface into a space form, generalizing and improving analogous radius estimates for embedded compact hypersurfaces obtained by Blaschke, Koutroufiotis and the authors. The results are obtained using an algebraic lemma and a tangency principle related with the length of the second fundamental form. The algebraic lemma also is used to improve a result for graphs due to Hasanis–Vlachos. The first author dedicates this work to his parents José (in memoriam) and Herondina     

Free and nonfree Voronoi polyhedra

The Voronoi polyhedron of some point v of a translation lattice is the closure of the set of points in space that are closer to v than to any other lattice points. Voronoi polyhedra are a special case of parallelohedra, i.e., polyhedra whose parallel translates can fill the entire space without gaps and common interior points. The Minkowski sum of a parallelohedron with a segment is not always a parallelohedron. A parallelohedron P is said to be free along a vector e if the sum of P with a segment of the line spanned by e is a parallelohedron. We prove a theorem stating that if the Voronoi polyhedron P _v (f) of a quadratic form f is free along some vector, then the Voronoi polyhedron P _v (g) of each form g lying in the closure of the L-domain of f is also free along some vector. For the dual root lattice E ₆*, and the infinite series of lattices D _2m ⁺ , m ≥ 4, we prove that their Voronoi polyhedra are nonfree in all directions.