境由心生

在现实生活中,有人总是企盼没有的,却忘了现成的,追求遥远的,却无视身边的永无止境的物质追求,让人变得贪婪;盲目的攀比,让人抱怨生活的不公境由心生,心情不好,就会失去一次次微笑着感受人生的喜悦,就会失去不少在情绪乐观时可以获得成功的机会……其实,在这个纷繁复杂、充满诱惑的社会,不羡慕别人,不轻贱目己,过自己喜欢过的日子,就是最好的日子,活自己喜欢的活法,就是最好的活法,按自己的天性度过自己的时日,就是天堂般的日子!     

2012年中考专题复习(1)——“数与式”

中考内容要求实数与代数式所考查的知识有:有理数,倒数,相反数,绝对值,数轴的运用,实数的大小比较,乘方,科学记数法,有效数字,二次根式,实数的估算,列代数式,解释代数式,求代数式的值,探求数与式的规律.     

生命因你而精彩

"轻轻地,你走进了我,带着一路风尘,积蓄着编辑们的辛勤汗水,如阳光如雨露如春风,滋润我那方贫瘠的珠心算土地,从此,漫长曲折的人生,找到了通往胜利的旅程。"这是摘自于一位忠实读者为本刊撰写的一首诗歌,文字虽朴实,读来却情真意切,感人心怀。在《珠算与珠心算》期刊创刊10周年的日子里,我再次想起这首诗,思绪万千,心潮澎湃,温暖与感动,自心底无边的延伸。     

巧用乘法公式解题

乘法公式是《整式的乘除》中的重要内容,在初中代数里有很广泛的应用,在一些竞赛试题中也是常考的热门内容,其题目形式多样,技巧性强,解题时应根据题目的结构特征,选择乘法公式恰当地变形,或是对题目条件进行灵活的处理,化繁为简,或是将题目转化为熟悉的形式,从而达到求解的目的,本文通过一些典型的习题,介绍利用乘法公式处理这些题目的一些常见技巧,帮助大家总结和积累解题的方法.     

会长张弘力在中国珠算心算协会第八届会员大会上的讲话

刚才,大家推选我为中国珠算心算协会第八届理事会会长,我感到十分荣幸,感谢财政部党组和各位理事对我的信任。与此同时,也深感责任重大,珠算心算对我而言,是陌生的全新的领域,担任这一领域如此重要的职务,既是莫大的荣誉,也是巨大的挑战,我将珍惜这一荣誉,竭尽全力,与各位理事、各位会员一道,并在你们的支持和帮助下,去迎接挑战。     

会长张弘力在中国珠算心算协会第八届会员大会上的讲话（2014年7月20日）

刚才,大家推选我为中国珠算心算协会第八届理事会会长,我感到十分荣幸,感谢财政部党组和各位理事对我的信任。与此同时,也深感责任重大,珠算心算对我而言,是陌生的全新的领域,担任这一领域如此重要的职务,既是莫大的荣誉,也是巨大的挑战,我将珍惜这一荣誉,竭尽全力,与各位理事、各位会员一道,并在你们的支持和帮助下,去迎接挑战。     

减少解题中的“废招”

解题应该简单,单刀直入,追求自然,直达问题的核心,不要兜圈子,尽量减少解题中的废招.这样才能抓住问题的实质,提高解题的效率,真正给人美的享受.     

追求新颖 彰显理念 体现特色——2008年高考江苏卷第17题品读

2008年高考江苏数学试卷的第17题是一个应用性问题,命题坚持新课标倡导的源于生活,应用数学,既是应用,又是数学的原则,设计新颖,深入浅出,通俗易懂,具有很好的教学引导性和命题示范性。     

三角形涉及面积的一个关系式及其应用

本文给出三角形涉及面积的一个有趣关系式,并举例说明它的应用.1结论定理如图1、2,在△ABC中,D,E,F分别是边AB,AC,BC(或其延长线)上的一点,且DE∥BC,EF∥AB,记△ADE,△BFD,△CEF的面     

新课程理念下对课堂有效提问的反思——从一节公开课的几个片断谈起

在新课程理念下,课堂教学的有效性是每一个教师所努力追求的目标．然而在平时的教学中,尤其是在公开课中,为了调控好教学时间,为了避免课堂中出现“意外”,为了设计上的面面俱到,为了……太多的因素干扰着课堂教学．于是,在问题的设置中,要么过分夸大教师的作用,不敢放手,变“引导”为“灌输”,忽视了学生的思维发展与情感体验,压缩了学生思考的空间,束缚住了他们的手脚．要么过分夸大学生的作用,过多地让学生讨论、交流,不敢插手,生怕干扰了学生,缺少必要的引导,学生学得肤浅,用课堂上表面的热闹掩盖了教学上的低效．为此,本文就浙教版八年级上册《等腰三角形的性质》,结合我校的一节公开课的几个片断,谈谈对课堂有效性提问的一些思考,供同行参考．     

无限域拉普拉斯方程问题的高阶边界条件及其应用

对无限域Laplace方程问题,推导出了高阶边界条件.在采用数值方法的有限域的外边界上应用高阶边界条件,可以在保证计算精度的前提下缩小数值求解域,从而减小计算工作量和少占用计算机内存.数值算例表明,一阶边界条件近似于精确边界条件,它明显地优于经典边界条件和二阶边界条件.     

Laplace方程边值问题的边界积分方程法

§ 1.　Introduction　　Inengineeringandtechnology ,theproblemofstaticelectricfieldscanbeattributedtotheboundaryproblemofLaplaceequationofstaticeletricpotentialfunction .Themethodsofclassi calmathematicalphysicscanbeonlyusedtosolveboundaryproblemofverysimpledomainandspecialboundarycondition .Althoughthemethodsoflimitedelementscanbeusedtosolvetheproblemsonarbitrarydomain ,butitneedstopartitionthewholedomainandtocalculateverycomplex .Theapproachofboundaryintegralequationistosolverelatedproblemsb…     

Exact boundary controllability for 1‐D quasilinear wave equations with dynamical boundary conditions

By equivalently replacing the dynamical boundary condition by a kind of nonlocal boundary conditions, and noting a hidden regularity of solution on the boundary with a dynamical boundary condition, a constructive method with modular structure is used to get the local exact boundary controllability for 1‐D quasilinear wave equations with dynamical boundary conditions. Copyright © 2016 John Wiley & Sons, Ltd.     

Absorbing boundary conditions for electromagnetic wave propagation

In this paper, the theoretical perfectly absorbing boundary condition on the boundary of a half-space domain is developed for the Maxwell system by considering the system as a whole instead of considering each component of the electromagnetic fields individually. This boundary condition allows any wave motion generated within the domain to pass through the boundary of the domain without generating any reflections back into the interior. By approximating this theoretical boundary condition a class of local absorbing boundary conditions for the Maxwell system can be constructed. Well-posedness in the sense of Kreiss of the Maxwell system with each of these local absorbing boundary conditions is established, and the reflection coefficients are computed as a plane wave strikes the artificial boundary. Numerical experiments are also provided to show the performance of these local absorbing boundary conditions

     

Characterizations of boundary pluripolar hulls

We present some basic properties of the so-called boundary relative extremal function and discuss boundary pluripolar sets and boundary pluripolar hulls. We show that for B-regular domains the boundary pluripolar hull is always trivial on the boundary of the domain and present a “boundary version” of Zeriahi’s theorem on the completeness of pluripolar sets.     

含开边界二维Stokes问题的Galerkin边界元解法

本文推导了含有开边界的二维有限域上Stokes问题的边界积分方程, 得出基于单层位势的第一类间接边界积分方程.对与之等价的边界变分方程用Galerkin边界元求解以得出单层位势的向量密度. 对于含有开边界端点的边界单元,采用特别的插值函数, 以模拟其固有的奇异性.论文用若干数值算例模拟了含有开边界的有限区域上不可压缩粘性流体的绕流.       

On the regularity of a free boundary near contact points with a fixed boundary

We investigate the regularity of a free boundary near contact points with a fixed boundary, with C1,1 boundary data, for an obstacle-like free boundary problem. We will show that under certain assumptions on the solution, and the boundary function, the free boundary is uniformly C¹ up to the fixed boundary. We will also construct some examples of irregular free boundaries.     

Adjoint and self-adjoint boundary value problems on a geometric graph

We consider boundary value problems of arbitrary order for linear differential equations on a geometric graph. Solutions of boundary value problems are coordinated at the interior vertices of the graph and satisfy given conditions at the boundary vertices. For considered boundary value problems, we construct adjoint boundary value problems and obtain a self-adjointness criterion. We describe the structure of the solution set of homogeneous self-adjoint boundary value problems with alternating coefficients of a differential equation and obtain nondegeneracy conditions for these boundary value problems.     

The nonlinear boundary layer to the Boltzmann equation with mixed boundary conditions for hard potentials

In this paper, the existence of boundary layer solutions to the Boltzmann equation for hard potential with mixed boundary condition, i.e., a linear combination of Dirichlet boundary condition and diffuse reflection boundary condition at the wall, is considered. The boundary condition is imposed on the incoming particles, and the solution is supposed to approach to a global Maxwellian in the far field. As for the problem with Dirichlet boundary condition (Chen et al., 2004 [5]), the existence of a solution highly depends on the Mach number of the far field Maxwellian. Furthermore, an implicit solvability condition on the boundary data which shows the codimension of the boundary data is related to the number of the positive characteristic speeds is also given.     

Generalized boundary conditions on representative volume elements and their use in determining the effective material properties

We discuss generalized boundary conditions for representative volume elements (RVE), which include the classical boundary conditions as special cases. From the generalization, stochastic boundary conditions are derived. These allows to adjust the the stiffness of the boundary conditions smoothly between the extremal cases of homogeneous strain and homogeneous stress boundary conditions. We found that it needs to be distinguished between the resistance of the boundary conditions against homogeneous and inhomogeneous RVE deformation. The stochastic BC can combine the moderate stiffness of the well known periodic boundary conditions with the high resistance against localization of the homogeneous strain boundary conditions. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)