Sobolev方程一个新的H~1-Galerkin混合有限元分析

研究了Sobolev方程的H~1-Galerkin混合有限元方法.利用不完全双二次元Q_2~-和一阶BDFM元,建立了一个新的混合元模式,通过Bramble-Hilbert引理,证明了单元对应的插值算子具有的高精度结果.进一步,对于半离散和向后欧拉全离散格式,分别导出了原始变量u在H~1-模和中间变量p在H(div)-模意义下的超逼近性质.     

欧拉：18世纪最伟大的数学家之一——纪念欧拉诞辰300周年

欧拉（Leonhard Euler 1707-1783），1707年4月15日出生于瑞士的巴塞尔一个牧师家庭．父亲是当地基督教加尔文派的教长，平时喜爱数学，也有所研究，曾从雅科布·伯努利学过数学，他是欧拉的数学启蒙教师．后来，欧拉师从约翰·伯努利．欧拉当初在巴塞尔文科学校学习时数学课程很少，到了假期，欧拉最感兴趣的是如饥似渴地读父亲所收藏的数学书籍．父亲希望儿子学神学，子承父业．1720年刚满13岁的欧拉考上了巴塞尔大学神学系，但是欧拉的数学才能很快就被当时著名的数学家约翰·伯努利发现，约翰·伯努利破例地单独给欧拉讲授数学，     

欧拉不等式三角形式的改进及其类似

在研究一组欧拉不等式三角形式的基础上,对部分不等式进行了改进,构建了两个新的欧拉不等式的三角形式.     

慧眼独具的盲人数学家—欧拉小传——纪念欧拉逝世200周年

一七○七年四月十五日数学史上杰出的数学家欧拉(Euler)诞生在瑞士第二名城巴塞尔(Basel)的一个殷实的家庭。父亲保罗·欧拉(Paul Euler),是个基督教加尔文派的教长,喜爱数学,是欧拉启蒙的数学老师。 欧拉幼年早慧,在家庭的教养下,聪颖过人。保罗希望欧拉学习神学,继承父业。一七二○年秋,把欧拉送进瑞士最古老的大学巴塞尔大学,学习神学、医学、东方语言。欧拉的聪慧与勤勉,赢得了该校数学教授约翰·伯努利(Jehann Bernoulli)的赏识(伯努利数学家族,祖孙四代蝉联共有十位数学家),并亲自单独面授数学。从此欧拉和他的儿子—数学家尼     

平衡子欧拉符号图及符号线图

符号图$S=(S^u,\sigma)$是以$S^u$作为底图并且满足$\sigma: E(S^u)\rightarrow\{+,-\}$. 设$E^-(S)$表示$S$的负边集. 如果$S^u$是欧拉的(或者分别是子欧拉的, 欧拉的且$|E^-(S)|$是偶数, 则$S$是欧拉符号图(或者分别是子欧拉符号图, 平衡欧拉符号图). 如果存在平衡欧拉符号图$S''$使得$S''$由$S$生成, 则$S$是平衡子欧拉符号图. 符号图$S$的线图$L(S)$也是一个符号图, 使得$L(S)$的点是$S$中的边, 其中$e_ie_j$是$L(S)$中的边当且仅当$e_i$和$e_j$在$S$中相邻,并且$e_ie_j$是$L(S)$中的负边当且仅当$e_i$和$e_j$在$S$中都是负边. 本文给出了两个符号图族$S$和$S''$,它们应用于刻画平衡子欧拉符号图和平衡子欧拉符号线图. 特别地, 本文证明了符号图$S$是平衡子欧拉的当且仅当$\not\in S$, $S$的符号线图是平衡子欧拉的当且仅当$S\not\in S''$.     

论欧拉的数学思想

欧拉 (LeonardEuler) 170 7年生于瑞士巴塞尔 ,1783年卒于彼得堡 ,是十八世纪首屈一指的大数学家、物理学家和天文学家 ,是历史上对数学贡献最大的四位数学家之一 .他深湛渊博的知识 ,无穷无尽的创造力和空前丰富的著作令后人叹为观止 ,他从 18岁起就开始写作 ,直到 76岁 .半个多世纪写下了很多书籍和论文 ,是数学史上著述最多的数学家之一 ,甚至每一个数学分支都可以看到欧拉的名字 ,从初等几何的欧拉线 ,多面体的欧拉定理 ,立体解析几何欧拉变换公式 ,四次方程的欧拉解法 ,到数论中的欧拉函数 ,微分方程的欧拉方程 ,级数论中的欧拉常数 ,…     

随机微分方程欧拉格式算法分析

首先给出了线性随机微分方程的欧拉格式算法,然后给出了非线性随机微分方程变步长的欧拉格式算法,接着讨论了其对初值的连续依赖性和收敛性.     

类拟的Euler公式

经典的欧拉公式描述了两曲面交线的曲率和曲面的法曲率以及曲面夹角之间的关系。本文给出了R3中曲面的法曲率的欧拉公式的简单证明。并得到一个关于曲面交线曲率及曲面测地曲率的类似的欧拉公式。     

一类广义欧拉函数方程的可解性

将Lehmer同余式从模素数的平方推广到模任意整数的平方,王容、廖群英定义了一类正整数n广义欧拉函数φ_n (5),并给出了准确计算公式,利用已有的广义欧拉函数计算公式,使用初等的方法和技巧,研究了一类广义欧拉函数方程φ₅(n)=n/d的正整数解.     

简化常数变易法求解二阶欧拉方程

将“常数变易”法求二阶非齐次欧拉方程特解的过程进行了简化,从而得出了求二阶欧拉方程的通解的一般公式.此方法简单、运算量小.     

The unstable spectrum of the Navier–Stokes operator in the limit of vanishing viscosity

The Navier–Stokes equations for the motion of an incompressible fluid in three dimensions are considered. A partition of the evolution operator into high frequency and low frequency parts is derived. This decomposition is used to prove that the eigenvalues of the Navier–Stokes operator in the inviscid limit converge precisely to the eigenvalues of the Euler operator beyond the essential spectrum.     

On the spectrum of Euler–Lagrange operator in the stability analysis of Bénard problem

In studying the stability of Bénard problem, we usually have to solve a variational problem to determine the critical Rayleigh number for linear or nonlinear stability. To solve the variational problem, one usually transforms it to an eigenvalue problem which is called Euler–Lagrange equations. An operator related to the Euler–Lagrange equations is usually referred to as Euler–Lagrange operator whose spectrum is investigated in this paper. We have shown that the operator possesses only the point spectrum consisting of real number, which forms a countable set. Moreover, it is found that the spectrum of the Euler–Lagrange operator depends on the thickness of the fluid layer.     

A Nash–Moser approach for the Euler–Arnold equations

We study the local well-posedness in the smooth category for a class of Euler equations. A Nash–Moser approach is used to extend, for the case of an invertible elliptic pseudo-differential operator, some results obtained by Escher and Kolev, with the help of some geometric arguments.     

Generation of Gevrey class semigroup by non‐selfadjoint Euler–Bernoulli beam model

Asymptotic and spectral properties of a non‐selfadjoint operator that is a dynamics generator for the Euler–Bernoulli beam model of a finite length are studied in this paper. The hyperbolic equation, which governs the vibrations of the Euler–Bernoulli beam model, is supplied with a one‐parameter family of physically meaningful boundary conditions containing damping terms. The initial boundary‐value problem is equivalent to the evolution equation that generates a strongly continuous semigroup in the state space of the system. It is found that the semigroup, being non‐analytic, belongs to Gevrey class semigroups. This means that the differentiability of such semigroup is slightly weaker than that of an analytic semigroup. In the forthcoming works, the results of the present paper will be applied (a) to the solution of the exact controllability problem for Euler–Bernoulli beam and (b) to spectral analysis of a planar network of serially connected Euler–Bernoulli beams modelling ‘flying wing configurations’ in aeronautic engineering. Copyright © 2006 John Wiley & Sons, Ltd.     

Necessary condition for eigensolutions of the 1-Laplace operator by means of inner variations

Eigenfunctions of the $p$ -Laplace operator for $p>1$ are defined to be critical points of an associated variational problem or, equivalently, to be solutions of the corresponding Euler–Lagrange equation. In the highly degenerated limit case of the 1-Laplace operator eigenfunctions can also be defined to be critical points of the corresponding variational problem if critical points are understood on the basis of the weak slope. However, the associated Euler–Lagrange equation has many solutions that are not critical points and, thus, it cannot be used for an equivalent definition. The present paper provides a new necessary condition for eigenfunctions of the 1-Laplace operator by means of inner variations of the associated variational problem and it is shown that this condition rules out certain solutions of the Euler–Lagrange equation that are not eigenfunctions.     

On the images of entire functions under the limit <Emphasis Type="Italic">q</Emphasis>-Bernstein operator

The limit q-Bernstein operator B _q comes out naturally as the limit for the sequence of q-Bernstein operators in the case 0 < q < 1: Alternatively, it can be viewed as a modification of the Szász-Mirakyan operator related to the Euler distribution. In this paper, a necessary and sufficient condition for a function g to be an image of an entire function under B _q is presented.     

Schrödinger operators on graphs and geometry I: Essentially bounded potentials

The inverse spectral problem for Schrödinger operators on finite compact metric graphs is investigated. The relations between the spectral asymptotics and geometric properties of the underlying graph are studied. It is proven that the Euler characteristic of the graph can be calculated from the spectrum of the Schrödinger operator in the case of essentially bounded real potentials and standard boundary conditions at the vertices. Several generalizations of the presented results are discussed.     

New predictor‐corrector scheme for solving nonlinear differential equations with Caputo‐Fabrizio operator

In this paper, we develop a new, simple, and accurate scheme to obtain approximate solution for nonlinear differential equation in the sense of Caputo‐Fabrizio operator. To derive this new predictor‐corrector scheme, which suits on Caputo‐Fabrizio operator, firstly, we obtain the corresponding initial value problem for the differential equation in the Caputo‐Fabrizio sense. Hence, by fractional Euler method and fractional trapeziodal rule, we obtain the predictor formula as well as corrector formula. Error analysis for this new method is derived. To test the validity and simplicity of this method, some illustrative examples for nonlinear differential equations are solved.     

Generating functions of the (<Emphasis Type="Italic">h,q</Emphasis>) extension of twisted Euler polynomials and numbers

By using p-adic q-deformed fermionic integral on ℤ _p , we construct new generating functions of the twisted (h, q)-Euler numbers and polynomials attached to a Dirichlet character χ. By applying Mellin transformation and derivative operator to these functions, we define twisted (h, q)-extension of zeta functions and l-functions, which interpolate the twisted (h, q)-extension of Euler numbers at negative integers. Moreover, we construct the partially twisted (h, q)-zeta function. We give some relations between the partially twisted (h, q)-zeta function and twisted (h, q)-extension of Euler numbers.      

A nonlinear Hamiltonian structure for the Euler equations

The Euler equations for inviscid incompressible fluid flow have a Hamiltonian structure in Eulerian coordinates, the Hamiltonian operator, though, depending on the vorticity. Conservation laws arise from two sources. One parameter symmetry groups, which are completely classified, yield the invariance of energy and linear and angular momenta. Degeneracies of the Hamiltonian operator lead in three dimensions to the total helicity invariant and in two dimensions to the area integrals reflecting the point-wise conservation of vorticity. It is conjectured that no further conservation laws exist, indicating that the Euler equations are not completely integrable, in particular, do not have soliton-like solutions.