具对流项热传导方程的源型解

文中对扩散对流方程u1 =uxx + ( un) x,　 ( x,t)∈ R× ( 0 ,T)的源型解进行研究 ,其中 n 0 .从数学上说 ,此类拟线性抛物型方程是一致抛物型的 ,由于方程带有对流项 ,故其具有双曲性 ,特别当时 n<1时 ,对流项 ( un) x在 {u=0 }上是奇异的 .此类方程的这些特性 ,给讨论其解的存在唯一性以及其他深入的性质造成了实质性的困难 .此处在一般的假设下 ( n 0 ) ,考虑以上方程 Cauchy问题 ,当初值为 Dirac测度时的解(以下称之为源型解 Source- type solution)的存在唯一性 ,正则性以及不存在性 ,此外我们还研究了解的渐近性和相似解的存在性问题 .     

一类非线性波动方程的初边值问题

研究一类四阶非线性波动方程的初边值问题:{utt-Δu-Δut-Δutt=μ|u|p-1u f(x,t),u|(e)Ω×(0,t)=0,u(x,0)=u0(x),ut(x,0)=u1(x);(1)得到了其广义解的存在性.     

广义Davey-Stewartson方程的新孤波解

用包络变换法得到广义 Davey-Stewartson 方程{iut+δuxx+uyy=n|u|2u+b1uvx,vxx+mvyy=(|u|2)x当δ<0时(即(-,+)和(-,-)型)的亮孤波解、暗孤波解、尖亮孤波解和尖暗孤波解.     

一类非线性椭圆方程正爆破解的存在性

研究了如下的非线性椭圆方程正爆破解存在性：{△u＋g（x）u^a│△↓u│q=ρ（x）f（u）,x∈Ω;其中Ω R^N（N≥3）。其中QCR“（N≥3）是一个C^2类有界区域或者Ω=R^N,a≤0,q∈[0,2]。运用上下解定理和摄动方法,得到了若干正爆破解存在的充分性条件,并就解存在的必要性做了论证。     

一类两点边值问题爆破解的存在性

借助积分的方法对问题{（φp（u′））′=λf（u（x））}limx→0^＋ u（x）=∞=limx→1^- u（x）爆破解的存在性进行了相关研究．     

非线性Sine-Gordon方程解的爆破和生命跨度

在Ω×[0,T)中考虑如下非线性Sine-Gordon方程初值问题解的爆破{utt-uxx=-sin u, x∈Ω;u(x,0)=u0(x), x∈Ω;ut(x,0)=u1(x), x∈Ω.这里,Ω是R中具有光滑边界(δ)Ω的有界域.在Dirichlet边界条件下,得到了其解爆破的若干充分条件,然后通过能量方法,得到了解的生命跨度的上界估计.     

一类非线性椭圆方程正爆破解的存在性

研究了如下的非线性椭圆方程正爆破解存在性:Δu+g(x)uα|u|q=ρ(x)f(u),x∈Ω;u(x)→+∞,x→Ω。其中ΩRN(N≥3)是一个C2类有界区域或者Ω=RN,α≤0,q∈[0,2]。运用上下解定理和摄动方法,得到了若干正爆破解存在的充分性条件,并就解存在的必要性做了论证。     

一类具有变号权的渐进线性椭圆方程解的存在性

研究渐进线性椭圆方程－Δu=[WTB1X]Q[WTBX](x)f(u),x∈Ω,u=0, x∈Ω解的存在性具有重要的意义,其中Ω是RN中的光滑有界区域,N≥1,假定非线性项f(u)在原点超线性,在无穷远点渐进线性增长,[WTB1X]Q[WTBX](x)为一变号的函数.将证明在适当的条件下,方程至少存在一个非平凡的解.     

对可吸收的渗流方程的源型解法的一些补充

讨论了当0＜m＜1-2/N(N≥3)时,柯西问题ut=Δum-up u(x,0)=0 x∈RN\{0}的非平凡解的存在性.     

利用特征根法求两类数列的通项公式

命题1：在数列{a}中a,已知首项a,且n≥2时,a=pa＋q（p≠1,q≠0）,则称方程x=px＋q为数列{a}的一阶特征方程,其特征根为x=,数列{a}的通项公式为a=（a-x）p＋x. 由以上命题可知,对于递推关系形如a=pa＋q（p≠1,q≠0）的数列可以通过解特征方程x=px＋q,构造等比数列{a-x},求{a}的通项.     

Fibonacci语言的性质研究

在由字母表 {u ,v}所生成的自由单式半群上定义了两类特殊的Fibonacci语言Fu ,v={u ,v ,uv ,vuv,… }和F0u ,v={u ,v,vu ,vuv,… } ,其中u ,v是两个定义在一个有限的字母表X上的非空字 .在这篇文章中 ,作者探讨了F1u ,v和F0u ,v中的具有相同的长度的字是一对共轭对 .当u ,v不是X+ 上同一个字母的方幂时 ,F1u ,v\{ {u ,v ,uv ,vuv}是一个本原字集 .一个非空的语言L是一个密码 ,若x1,x2 ,… ,xn,y1,y2 ,… ,ym ∈L ,x1,x2 …xn=y1,y2 …ym 成立就意味着n =m和xi=yi,i=1 ,2 ,… ,n .当k 2时 ,语言Fk={ωnk\{u ,v,uv,vuv|n 1 }是一个密码 ,其中ωnk指的是第nk -th个Fibonacci字     

Minority aspirations and the revival of indigenous peoples

The growing world-wide sensitivity to the aspirations of indigenous peoples is to be welcomed. However, there is still a tendency which should be avoided: to lump the claims of indigenous peoples with those of minorities. Indigenous peoples are the heirs of long-established political, social and cultural communities which have been oppressed for centuries or victimized by policies of genocide or forced assimilation into the approved language and religion of the dominating community. These forms of destruction can only be truly ended by returning to indigenous peoples a degree of autonomy which will ensure that they have real control over their future. Indigenous peoples should be able to create institutions, including schools, where their languages, religions and cultures are permitted to flourish without interference.

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Zusammenfassung Wachsende weltweite Sensibilisierung gegenüber den Bedürfnissen einheimischer Völker sind sicherlich begrüßenswert. Vermieden werden sollte jedoch die Tendenz, die Ansprüche einheimischer Völker mit denen der Minderheiten gleichzusetzen. Einheimische Völker sind Erben langansässiger politischer, sozialer und kultureller Gemeinden, die jahrhundertelang unterdrückt oder Opfer politisch motivierten Massenmordes wurden, oder aber die dazu gezwungen wurden, sich der Sprache und Religion der dominierenden Gruppe zu unterwerfen. Diese Art von Zerstörung kann nur dann endgültig beendet werden, wenn einheimischen Völkern die für eine wahre Kontrolle über ihre Zukunft nötige Autonomie zugestanden wird. Einheimische Völker sollten die Möglichkeit bekommen, Institutionen und Schulen einzurichten zur Pflege und Weiterentwicklung ihrer eigenen Sprache, Religion und Kultur ohne Intervention von dritter Seite.

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Resumen La creciente sensibilidad que se registra en todo el mundo ante las aspiraciones de los indígenas es un hecho muy positivo. Sin embargo, aun subsiste una tendencia que debe evitarse: no deben agruparse las reivindicaciones de los indígenas con las exigencias de minorías. Los indígenas son los herederos de communidades políticas, sociales y culturales establecidas desde hace mucho tiempo, que fucron oprimidas durante siglos o víctimas de políticas de genocidios o de asimilación forzada a la lengua y a la religión oficial de la comunidad dominante. Estas formas de destrución solamente podrán suprimirse devolviendo a los indígenas un grado de autonomia que les asegure un real control de su propio futuro. Los indígenas deberían recibir la posibilidad de crear instituciones, e incluso escuelas, donde sus lenguas, religiones y culturas puedan florecer sin sufrir interferencias.

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Résumé La sensibilisation croissante au niveau mondial pour les aspirations des populations autochtones doit être encouragée. Une tendance reste cependant à éviter: confondre les revendications des peuples autochtones avec celles des minorités. Les premiers sont les héritiers de communautés politiques, sociales et culturelles implantées de longue date, qui ont été opprimées pendant des siècles, ou sont devenues victimes de politiques génocides, ou encore forcées à l'assimilation de la langue et de la religion autorisées par la communauté dominatrice. On ne pourra mettre un terme définitif à ces formes de destruction que si les populations autochtones recouvrent un minimum d'autonomie qui leur assurera une maîtrise véritable de leur avenir. Les peuples autochtones devraient pouvoir créer des institutions, dont les écoles, où leurs langues, leurs religions et leurs cultures seraient libres de s'épanouir sans ingérence.

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一类二阶非线性差分方程的振动性

本文研究二阶差分方程(3)的振动性,获得了方程所解振动的充分条件。     

Critical thinking and the Spock Fallacy

Conventional instruction in critical thinking technique tends to conflate logical thinking with rational or good thinking. But in doing so, it ignores the creative and intuitive functions of rationality, thereby encouraging a mechanically rote approach to textual analysis, problem solving and problem construction. This overemphasis upon straightforwardly logical calculus of justification functions, and its concomitant deemphasis of intuitive pattern of discovery ones, constitute the Spock Fallacy. Its epistemological weakness and pedagogical hazards are explored.The author of two books and numerous articles, one of his specialties is philosophy of education and critical thinking.     

Impact and adjustment: foreign students in comparative perspective

Foreign study is a multifaceted phenomenon - its impact is felt on academic institutions in both the host and sending countries, on the economies of nations, and of course on the individuals involved. With more than one million students studying abroad, foreign study has assumed considerable importance in higher education planning. This article considers the many aspects of foreign study and discusses the interrelationships of these elements. The policies of the host nations, for example, have an impact on higher education planning in the sending countries. The non-return of foreign students, traditionally referred to as the brain drain, is considerably more complex than was once thought since Third World graduates settled in the industrialized nations often retain contacts with their home countries and increasingly return after a period abroad. This article also considers the various push and pull factors which determine the constantly changing flow of foreign students.This study was supported by the Organisation for Economic Co-operation and Development, Centre for Educational Research and Innovation. It was presented at the International Seminar on Higher Education and the Flow of Foreign Students, convened by the Hochschul-Informations-System, with support from the Federal Ministry of Education and Science and the Lower Saxony Ministry of Science and Arts in Hannover, Germany on 26th–28th April 1990.     

C_m·S_n的邻点可区别边染色

V(Cm·Sn)={ui|i=1,2,L,m}∪{vij|i=1,2,L,m;j=1,2,L,n}, E(Cm?Sn)={v11v21,v21v31,Lv(m?1)1vm1,vm1v11}∪{uivij|i=1,2,L,m;j=1,2,L,n}.本文给出了的邻点可区别的边色数。     

Varying paths for learning to revise

The paper draws on the Vygotskyan view of instruction, advocating the support of learners within their individual Zones of Proximal Development. It describes an instructional design developed iteratively—gradually building in scaffolding techniques to support the use of the procedural facilitation of text evaluation during revision—and the open-ended management of its provision to students, so that they could fade it out themselves.The study took place in a writing class for students at basic writing levels. The present, post hoc analysis is concerned with individual differences among three members of the class identified as weak, intermediate and more advanced novices while learning to revise within that program.     

拟线性抛物型方程在第三边值条件下的极大值原理

文章以线性抛物型方程的弱极值原理和强极值原理为主要工具,讨论了拟线性抛物型方程β（tu）=Δu＋（fx,t,u）解的泛函V（x,）t=g（u）ut＋h（u）和β（tu）=Δu＋（fu）解的含梯度泛函P（x,t,u,u）k=塄u2＋2Z（）tF（u）（F＇=）f,在第三边值条件下的极大值原理。     

一类EV模型中参数σ~2的加权M估计的渐近正态性

考虑变系数多维线性结构关系EV模型y=xTβ(t),Y=y+ε,X=x+u,利用文[4]构造的参数β(t)在t=t0处的参数β(t0)的估计量βn(t0)构造参数σ2的估计量σn2,并证明它具有渐近正态性.     

一类半线性椭圆方程解的存在性问题

主要应用环绕定理及一些解的估计来讨论一类半线性椭圆方程:-△u-μ/(|x|2)u=k(x)|u|2*-2u+λu,u∈H01(Ω),当k(x)满足一定条件时,方程存在一个非平凡解。