矩形上的Bernstein多项式的逼近阶

1己1.当上.J二二J设j(动是定义在汇0,l]区间上的函数,与它相联系的Bernstein多项式为“·(‘;小一‘t0j(分:(x)(1 .1)这儿人们熟知(例如见〔1]) 当f任C[0,1]时,了:闭:一(冷‘(卜劝卜‘·,用B,(f)来逼近函数f有如下结果:一l厂一刀。(厂)l!_一。(。(。一去))当,任e‘ro,1]时,i一了一刀二(了)11一。(n一告二(了,,,一专)) 当f任CZ[0,1]时,}!f一B,(f){}。=O(n一‘)1981年,H.H.Gonska(见〔2〕,〔3了)证明了(1 .2)(1 .3)(1 .4)24第五卷 }1了一刀。(j)一l一镇3 .2502(f;,一香)n一朴是二阶的平滑模。(l .5)包含了(l .2)一(l.刃的结果。(1 .5)这…     

关于三次样条函数界值问题的注记

对区间〔a,如上的分划△:a二x。…     

e的各种连分数表达式

引理1如果}a。{乒z(n=1,2,…),则有一1-+工十…+卫一十a 22a Zff一x…二二一一a 12_…(1) .口l证设一利用一l 口l千口么 1 Gf+l 1 口. 1a,+b, :、1Q二(i=注,2扒”al+aZ)安则外二叮一二,:认而请a么+aa as+a,+1了a。一x+a:1一内王a么ax一’价.么一a未a盆+a之夕乃al+处怨J2 ,︸如以aQ土a。*一,一=一1+一共一卜 a‘宁O,!尹’ 0.毛一一二幸勺.-a,扩节花,十q:曰声卫‘_ 口备 a 12a:+42暇+05含.尸声一般地,+一里一十.,.+01a,a.=二__一华生一 。,d:扩取二:.二吐红 卜,一磷十a.。丫{“·‘)l,上边产碑 在(z)中取a=知!,、当叭军吐吟举则有居卜 1 仁…     

不定常燃烧放热反应问题解的全局渐近性态

号1.引言本文考虑不定常燃烧放热反应问题:介妙一+了“+、exp厂二一典,、1.“‘\‘,“u‘}竺’‘一0,..\u1卜.=甲气劣).二o,x〔口,t〔(o,OO),(1 .1)这里“是无里纲温度,口是R“(,=1,2,3)中的一个有界区域.a口是口的边界,才是Lap-lacian算子,又>o是反应速率参数,召>o是与能量有关的参数,甲(x))0是初始温度分布. 当甲(x)满足一定的条件时,(1.1)的正解“(x,t)的存在性及渐近性lim。(、,t)二石(x)在肛得到证明,这里斌x)是(1.1)的定常解,即它满足应.用数学与计算数学学报2卷(一岸丽)一”,/〔“(1 .2)、‘}‘{介“货’p受到阁中计算结果启示,我…     

无字的证明四则

1 sin(2九十l)0一sin()十Zsino义c璐2功皿创.口2一口.‘皿目的口里口,肠.口日泣.莽二拼几州—卜—州2,+2十…十,一冬、(,+1) 乙13十23+…十沪=(喜。(。+l)): 乙{“{:艺X盆一3 x3,推夏.x二.(.+1夕3交错平方和一三角数,‘2一(。一l)2十…十(一l)一‘(l)2 门__凡,,_1、。‘二_,.、2一—‘一J、lj、,,几j— 杏日(,,)(召十1) 2撰一尸4·个反止切恒等式和一个反止切级数},一2寸,草+一”l户尸,孟,,.J匕‘‘r‘I司l一 甲1 .中卜生一护+n宁丫.,泞一·一︻宁几!!!N口)亡-叫1一t nZ净告)、l.厂、二一, ,、习井.。aretan粗十are扭n 1护十升十1~arctan…     

ON DISCRETE PHENOMENA IN THE MIXED PROBLEM

On discrete phenomena in uniqueness of the initial value problem, F. Treves studied an interesting example and proved that the Oauohy problem \[\left\{ \begin{array}{l} {L_p}u = {u_{xx}} - {x^2}{u_{tt}} + p{u_t} = 0,t \ge 0;\u(x,0) = {u_t}(x,0) = 0, \end{array} \right.\] has non-triyial solutions if and only if p = 3, 5, …. Wang Guang-ymg and others proved that the Oauohy problem \[\left\{ \begin{array}{l} {L_p}u = 0,t \ge 0;\u(x,0) = {\varphi _1}(x);{u_t}(x,0) = {\varphi _2}(x), \end{array} \right.\] and Goursat problem \[\left\{ \begin{array}{l} {L_p}u = 0,t \ge \frac{{{x^2}}}{2};\u(x,\frac{{{x^2}}}{2}) = {\varphi _3}(x), \end{array} \right.\] both have a unique solution if and only if p≠1, 3, 5, …. In this paper, we discuss in detail the equation Lvu = 0 for discrete phenomena. We prove that solution of the mixed problem \[\left\{ \begin{array}{l} {L_p}u = 0,x \ge 0,t \ge 0,\u(x,0) = \varphi (x),\{u_t}(x,0) = \psi (x),\u(0,t) = 0 \end{array} \right.\] is not only existent but also unique, for р≠3, 7, 11，…，neither existence nor uniqueness could be proved in this problem, for p = 3, 7, 11，….，more precisely, only under some compatibility condition can the solution exist for the equation \({L_p}u = 0\).     

数列、极限、数学归纳法

一、选姆.(有且镬(r}‘·个答案正确) 1.数李l]{u.}的11介,。环1 fll为S二JIS.二,.。:(,:二l,2,3…).‘{‘}‘a.圣J亡(). (A)只足冷绘狄列.(B)只足等比数叫. (C)常数列,(D)既炸等袱数列.也一{卜’勺卜认列. 2一若口,b.,’成’引上数列.则山数.l(x)=。x气bx c的图象‘jx轴的之点数为(). (A)o个.(B)’含r,x个. (C)了丁两个不i,J交点.(D)不能内‘二. 3.一个冲数是鸿数的等兰数列.:饮厂和,二禹I-2ru 朽U数项和分别为:峪{i!30.宁则浪数刊的,犷之数勺( (人)卫0.(B)22 ‘.一个三角形的行。·谈比万).(C)卫0.毛内有l!戊等_之(上少)8.j少戈等…     

关于谢盛刚的“表大偶数为素数与至多三个素数的乘积之和”一文的一些意见

我们认为谢盛刚在文【1]中引理1的证明是错的,在该文的第209页最后第三行有/_,__,,_产Zeyd“户咒了d“、Cl,x_lj,.j,0件石一l—一、—卜丁一份一‘户l!3“一8_,_3“一8.__3“一8 J73“一81109‘劣\l。—一l一—109—/ F“8 1616 >5.2斗9967 cz,x二/109,二.我们将证明上式是错的,实际上我们将证明下式一定成立:/_,__,J_户82,了du fs 3201d“\l,工/,0,。一协—一、—、!13“一8二3“一8,3“一8 J73“一81\!。—一1一—109—/ 夕,8 1616全已兰相似文献   

Initial Boundary Value Problem for One Class of System of Multi- Dimensional Inhomogeneous GBBM Equations

This paper studies the following initial-boundary value problem for the system of multidimensional inhomogeneous GBBM equations $[\begin{array}{l} {u_r} - \Delta {u_i} + \sum\limits_{i = 1}^n {\frac{\partial }{{\partial {x_i}}}} grad\varphi (u) = f(u),{\rm{ (1}}{\rm{.1)}}\u{|_{t = 0}} = {u_0}(x),x \in \Omega ,{\rm{ (1}}{\rm{.2)}}\u{|_{\partial \Omega }} = 0,t \ge 0,{\rm{ (1}}{\rm{.3)}} \end{array}\]$ The existence and uniqueness of the global solution for the problem(l.l) (1.2) (1.3) are proved. The asymptotic behavior and “blow up” phenomenon of the solution for the problem (1.1) (1.2) (1.3) are investigated under certain conditions.     

ON THE INITIAL BOUNDARY VALUE PROBLEMS FOR QUASILINEAR SYMMETRIC HYPERBOILC SYSTEM AND THEIR APPLICATIONS

In this paper we discuss the initial-boundary value problems for qnasilinear gymmetrio hyperbolic system and their applications. It is proved that Theorem 1, Suppose \(\Omega \) is a bomded domain, its boundary \(\partial \Omega \) is sufficient smooth. We consider the quasilinear symmetric hyperbolic system \[\sum\limits_{i = 0}^n {{a^i}(x,u)\frac{{\partial u}}{{\partial {x_i}}}} = f(x,u)\] in the domain \([0,h] \times \Omega \). The initial-boimda/ry conditions \[\begin{array}{l} {\left. u \right|_{{x_0} = 0}} = 0\{\left. {Mu} \right|_{\partial \Omega }} = 0 \end{array}\] are given. If \({a^0}\) is positive definite，\(\partial \Omega \) is noncharaGieristic, \(Mu = 0\) is stable admissible and all coefficients are smooth enough, some of derivatives of \(f(x,0)\) at \({{x_0} = 0}\) vanish., then the smooth solution of (1), (2) uniquely exists, if h is sufficiently small. Theorem 2. We consider the semi-Unear symmetric hyperbolic system \[\sum\limits_{i = 0}^n {{a^i}(x,u)\frac{{\partial u}}{{\partial {x_i}}}} = f(x,u)\] The initial-boundary conditions are still \[\begin{array}{l} {\left. u \right|_{{x_0} = 0}} = 0\{\left. {Mu} \right|_{\partial \Omega }} = 0 \end{array}\] If the bowndary \(\partial \Omega \) is a regular characteristic, \(Mu = 0\) is normally admissible and other conditions is the same as that in the theorem 1., then the smooth solution of (3), (4) still wriiquely exists if hM sufficiently small.     

关于β级α-凸函数的一点注记

荟1.引言 记单位圆D={z:l2!相似文献   

对一道赛题解法的探究

1986年全国数学竞赛第设实数u、b、。满足 l丫一bc一sa+7=()·试第1题第咬3川、题为:那么“的取值范It1是①② !扩+扩+b‘、一6a+6=‘j(A)(一co,+co);(I弓)(一oo,1 JU〔9,+co);(C)(0,7);(I))r 1.9〕.标准解答是,山题给条件得lbc三丫一sa+7l夕十已+bc=6“一6②一①x3得(l,一‘〕’=一3(‘,一)(u一冬,)③ .’一3(a一l)(u一9))(),故l石a石9 答案为(u). 我们认为此种解法不妥。因为.若口)十(劲,得 (b+‘.)二丫一2“十l=(‘:一I)④ bc〔R.而(“一l)J要0二‘一co<‘,<十oo,答案应为(A). 又若将①代人②得 粉+‘“=一丫+14‘,一13二一(‘,一1)…     

Poisson积分的几个证明

圆内调和函数u(z)=u(re‘口)=u(戈,夕)的Poisson积分表示式u(r’“)=l不2,,:‘、1一rZ—l刁“吸e’了J万eseses~eseseses--一-二;,a梦Z兀汉0’‘1~Zrcos气势一口)+r‘O(r<1(1) 0簇0(2兀是一个重要公式,其中“(z)在单位圆1川<1内调和,在闭圆}川(1上连续,它在很多理论实际问题都有重要的应用。这里给出几个证明。 1.用Cauchy公式来证明 在一些教科书中都用这种方法来证明,这里试图讲得更严格些。 对于在圆{川<王内的调和函数。(习二。(x,y),利用线积分可以构造出它的共扼调和函数:·‘·,=·(二,,,一J(,,,)(0,0)乡“Jy a“aX十—aV 刁X因…     

一类不等式的证明、推广及应用

考察下面一组不等式:若u、b〔R,且“+b“L_.11、l_!、_25则(“+言)(b+言))分二(2+告)’=l,《l)、..r夕才苦万,、‘若a、权“〔R+,且a+则(a+告)(。+寺)(‘+b+f“生))‘Il《只其)I‘.1、,_、一六下布一二1.币十二犷l,气乙) ‘口、。》I(告一:)+2)(卜,)(斗一:)+:一,+干·不应用这·结论.(2)式是很难i正币冬手的, (_几) 沿川(2)的证法或用数学归纳法去证明推万”了的《3)式,都将会遇到十分未杂的运竹.难以奏效,必须另辟新径.分析:(.r,+止如若上不等式皆正确,有理由猜侧:若￡〔R舟(;二l,艺,…,,)It、.+:,+…+x.二l件乙,11调协这,,个因式,能否…     

EXISTENCE OF DISCONTINUOUS SOLUTIONS FOR A DOUBLY DEGENERATE ELLIPTIC EQUATIONS ON $R^N$

It is demonstrated that under the hypotheses I—III the problem $\[\left\{ {\begin{array}{*{20}{c}} {div((k(U) + \varepsilon )|DU{|^{M - 1}}DU) = f(|x|,U) + \varepsilon U{\text{ }}in{\text{ }}{R^N},N > 1,{\text{ (1}}{\text{.1}}{{\text{)}}_\varepsilon }} \ {U(0) > 0,U(x) \geqslant 0{\text{ on }}{R^N},U(x) \to 0{\text{ as }}|x| \to + \infty {\text{ }}(1.2)} \end{array}} \right.\]$ for each fixed $\epsilon >0$ has infinitely many distinct radially symmetric solutions $U_\epsilon=V_\epsilon(|x|)$ such that $V_\epsilon(s),s^{N-1}(k(V_\epsilon(s))+\epsilon)|V''(s)|^{M-1}V''_\epsilon(s)\in C[0,+\infinity)\capC^1(0,+\infinity)$, $\[\left\{ {\begin{array}{*{20}{c}} {({s^{N - 1}}(k({V_\varepsilon }(s)) + \varepsilon )|V''(s){|^{M - 1}}V''(s)) = {\varepsilon ^{N - 1}}(f(s,{V_\varepsilon }(s)) + \varepsilon {V_\varepsilon }(s))for{\text{ }}s > 0,{{(1.3)}_\varepsilon }} \ {{V_\varepsilon }(0) = B > 0,{V_\varepsilon }(s) \geqslant 0{\text{ for }}s > 0,and{\text{ }}{V_\varepsilon }( + \infty ) = 0,(1.4)} \end{array}} \right.\]$ where B is a positive number chosen arbitrarily, which extends the result in [3]. In particular, the author proves that $U_0(x)=V_0(|x|)$ is a weak solution of the problem $(l.l)_0-(1.2)$.     

二次函数图象性质的应用点滴

一、利用“性胶”求扭值. 例1求x〔〔0.,l〕s月,/(二),x“+(2一6a)x+sa,的最小位,刀将得到的最小值看作是。的函数g(。).洲出它的图象. 解厂整理:/(二)盖〔,一(3a一1)〕’一6a“+6a一1. 设j(x)在x〔〔。,幻内鼓小值为夕.”势“3一<。,“·:·泣{J·<{.在。(二、1讨、,f(二)是增区数(图l)…g二f(0)=3。“2’)当:、,a一<,,尽},;‘·<:竹寸.口J、二工一3。一1时j(x)最刁、(图2),所以夕=f(3。一l)二一6。“+〔a气l3‘)当s。一J):。JJ。);时,在。《二<,;”:j、,) O是减函数(图3).所以g=l(l)=3。“一助+3二:(。一l)“ l龙{此得 3(。一)2g(a)=一…     

On Applications of Vector Measure to the Optimal Control Theory for Distributed Parameter Systems

Let X and Z be two reflexive Banach spaces, U\in Z and b(\cdot,\cdot):[t_0,T]*U\rightarrow X continuous. Suppose $x(t)\equiv x(t,u(\cdot))$ is a function from [t_0, T] into X , satisfying the distrbnted parameter system $dx(t)\dt=A(t)x(t)+b(t,u(t)),t_0+\int_t_0^T {+r(t,u(t))dt}$. We have proved the following theorem. Theorem. Suppose u^*(\cdot) is the optimal control function, $x^*(t)=x(t,u^*(\cdot))$ and $\psi (t)=-U'(T,t)Q_1x^*(T)-\int_t^T{U'(\sigma,t)Q(\sigma)x^*(\sigma)d\sigma}$, then the maximum principle $<\psi(t),b(t,u^*(t))>-1/2r(t,u^*(t))=\mathop {\max }\limits_{u \in U} {\psi (t),b(t,u)>-1/2r(t,u)}$ (16) holds for almost all t on [t_0, T ].     

一类多目标最优控制问题的广义鞍点理论

本文考虑的多目标最优控制问题为f(x,u,t)dt,rOfJ中(劣,u)=必(t)=A(t)工(t) B(t),a .e.[OT〕,二(0)=劣。,g(“,t)墓0,对丫t任〔OT〕,劣任AC”【OT〕,u任L:[OT〕, n 扭/11!l!尸F rr/rr rT_rT_.、T其中)。f‘“,“,‘’d‘垒L」。f,“,“,‘’d‘,」。f,“,“,‘’d‘,‘”,J。f,(劣,“,‘’“‘)中(二,。)垒(价;(二,u),功2(二,u),…,价,(劣,。))T,所以 rT功“x,“’“〕。f“‘,“,‘’d‘,“二‘,“,一p,·AC”〔oT〕为〔oT〕上绝对连续n维向量函数空间,L:〔OT〕为印T」上勒贝格测度基本有界,维向量函数空间.f‘:R”xRmx〔oT…     

非线性抛物型方程的一类边值问题

本文讨论了下述问题提法的正确性:在曲线边界区域豆笼I。(t)《x(l,(t);o《t(T圣上非线性抛物型方程边值问题器一、(x,‘,一器)器 二(X,‘,。,器)(l) u(x,0)=甲(x) u(几(t),t)二冲。(t),的解是存在且唯一的幻 为证明问题(l)(2)解的存在性,·:(,、(才),才)一、:(,,。(,1(,),,))}(2)首先考虑常微分方程的如下边值问题dZu_1 du\硕呀r=从x,“,丽厂) “(0)二冲。,u,(l)二冲,(u(l)) 利用C.H.EopHlllTe八H先验估计方法与Leray一Schauder 定理1若问题(3)(4)满足 (l)对0(x(l上的一切u值有F二(x,u,。,))a>o,取等号),心,(0)=0(a为常数)。 (3) (4)…     

法国Ecole Polytechmque笔试入学试题

1.设x为实数,整数Q李1.令S、‘,)二之业罗兰试证·““(‘) f‘5 in(Zq+1)兀,:,=1—a封一工 J 0 Sln材U2.令·(叫匕_: 、Sln介材月U“二0o<}u{<2.试证《。)在(·1,+l)申连续可微.试证存在一个常数A:,当x〔〔O,15、(小二一耳 几兀J口名叮+!,韶名Sin”。 一〔止V合〕以及对一切整数“》‘时,}、念便有 。)计算s。(冬)之值,并由使上述不等式推出积分f一圣些兰、,的收敛性,并求其值. ”“’、2‘’~一’‘’一一一一”‘一”一一一’‘一J0,”--一’一一’一’一- 3.验证存在一个实数AZ,使得对于V实数二和整数q>1,不等式}又(劝l成A:成立…