圆的直径式方程的妙求活用

若知圆的一直径的两端点Ａ (ｘ1,ｙ1) ,Ｂ(ｘ2 ,ｙ2 ) ,则圆的方程为 (ｘ -ｘ1) (ｘ -ｘ2 ) + (ｙ - ｙ1) (ｙ -ｙ2 ) =0 .特别地 ,若Ａ ,Ｂ为一直线和一圆锥曲线的两交点 ,则可妙求圆的方程 ,下面给出一个定理 .定理　设直线 ｆ(ｘ ,ｙ) =0和二次曲线 ｇ(ｘ ,ｙ)=0交于Ａ ,Ｂ两点 ,联立两方程 ,分别消去 ｙ和ｘ得ｕ(ｘ) =0及ｖ(ｙ) =0 (其中ｕ(ｘ)和ｖ(ｙ)的二次项系数相等 ) ,则以ＡＢ为直径的圆的方程为ｕ(ｘ)+ｖ(ｙ) =0 .证明　设Ａ(ｘ1,ｙ1) ,Ｂ(ｘ2 ,ｙ2 ) ,显然ｘ1,ｘ2 是方程ｕ(ｘ) =0的两个根 ;ｙ1,ｙ2 是方程ｖ(ｙ) =0的两个根 ,…     

一类退缩的椭圆型方程弱解的正则性

本文给出了一类退缩的拟线性椭圆型方程－Ｄｉｖ「↓ｕ｜＾ｐ－２↓ｕ＋Ｆ（ｘ,ｕ）」＝Ｂ（ｘ,ｕ,↓ｕ）在Ｗ＾１,ｐ（Ω）中弱解的Ｃ＾１,λｌｏｃ（Ω）正则性,其中Ω为Ｒ＾Ｎ中行一区域。     

P-调和映射流的存在性与不唯一性

构造了ｐ 调和发展方程的初边值问题的一个整体弱解；证明了当初值ｕ０（ｘ）是弱ｐ 调和映射但不是弱ｐ 驻调和映射时问题弱解的不唯一性．     

一类非线性退化椭圆型偏微分方程Dirichlet问题的非平凡弱解

王传芳在文［１］中研究了一类非线性退化椭圆方程－Ｄｉ（ｘ１ｍａ·Ｄｉｕ）＝｜ｕ｜ｓ－１·ｕ＋ｈ（ｘ）的Ｄｉｒｉｃｈｌｅｔ问题，建立了一套指数ｐ＝２的带权Ｓｏｂｏｌｅｖ空间及其嵌入和嵌入紧性理论，用扰动方法得到问题无穷多解的存在性．本文将此理论推广到指数Ｐ≥２的情形，据此推广了的理论研究一类非线性退化椭圆方程－Ｄｉ（｜ｘｍ｜ａ·｜Ｄｕ｜ｐ－２·Ｄｉｕ）＝ｆ（ｘ，ｕ）的Ｄｉｒｉｃｈｌｅｔ问题．利用临界点理论得到问题的非平凡弱解及无穷多个非平凡弱解．同时对解的不存在性进行了讨论．     

Monotone Iterative Method for Set valued Quasilinear Elliptic Boundary Value Problems

§ 1.ＰｒｏｂｌｅｍａｎｄＡｓｓｕｍｐｔｉｏｎｓ　Ｔｈｉｓｐａｐｅｒｄｅａｌｓｗｉｔｈｔｈｅｓｏｌｕｔｉｏｎｓｏｆｔｈｅｆｏｌｌｏｗｉｎｇｄｉｆｆｅｒｅｎｔｉａｌｉｎｃｌｕｓｉｏｎｐｒｏｂｌｅｍ :Ａｕ∈ｆ(ｘ,ｕ) ,ｘ∈Ω ;ｕ=0 ,ｘ∈ Ω ,(1 )ｗｈｅｒｅＡｕ(ｘ) =-∑Ｎｉ=1Ｄｉ[ａｉ(ｘ ,Ｄｕ(ｘ) ) ] ,Ω ＲＮｉｓａｂｏｕｎｄｅｄｄｏｍａｉｎｗｉｔｈｐｉｅｃｅｗｉｓｅＬｉｐｓｃｈｉｔｚｂｏｕｎｄａｒｙ Ω ,Ｄｕ =(Ｄ1ｕ ,Ｄ2 ｕ ,… ,ＤＮｕ) ,Ｄｉｕ = ｕ ｘｉ,ｉ=1 ,2 ,… ,Ｎ ,ａｎｄｆ:Ω×Ｒ→ 2 Ｒｉｓａ…     

包含测度的椭圆型方程解的Hlder连续性

考虑包含测度μ的椭圆型方程－ｄｉｖＡ（ｘ，ｕ，ｕ）＋Ｂ（ｘ，ｕ，ｕ）＝μ，在Ｇ内，ξ·Ａ（ｘ，ｕ，ξ）｜ξ｜ｐ－ｆ０（ｘ），１＜ｐ＜ｎ，｜Ａ（ｘ，ｕ，ξ）｜κ｜ξ｜ｐ－１＋ｆ１（ｘ），κ１，｜Ｂ（ｘ，ｕ，ξ）｜ｃ（ｘ）｜ξ｜γ＋ｆ２（ｘ），ｐ－１γｐ在γ＝ｐ－１的情况，为证有界解的Ｈｌｄｅｒ连续性，只需ｃ（ｘ）∈Ｌｎ（Ｇ）     

一类非线性渗流方程的Cauchy问题

讨论具有强非线性源和对流项的一般渗流方程以ＲＮ中某有界连续函数ｕ０（ｘ）或某一Ｒａｄｏｎ测度为初值的Ｃａｕｃｈｙ问题弱解的存在性，得到关于解的一系列重要估计．     

一类拟线性抛物型方程广义解的Hlder连续性

考虑如下拟线性抛物型方程ｕｔ－ｄｉｖＡ（ｘ，ｔ，ｕ，ｕ）＋Ｂ（ｘ，ｔ，ｕ，ｕ）＝０在Ａ，Ｂ满足很一般的结构条件下证明了它的广义解在Ｑ＝Ｇ×（０，Ｔ）上的局部Ｈｌｄｅｒ连续性     

一类似线性抛物型方程广义解的Hoelder连续性

考虑如下拟线性抛物型方程ｕ２－ｄｉｖＡ（ｘ，ｔ，ｕ，↓△ｕ）＋Ｂ（ｘ，ｔ，ｕ，↓△ｕ）＝０在Ａ，Ｂ满足很一般的结构条件下证明了它的广义解在Ｑ＝Ｇ×（０，Ｔ）上的局部Ｈｏｅｌｄｅｒ连续性。     

一类退缩椭园型方程弱解的正则性

本文得出一类形如：－Ｄｉｖ（ｇ（｜Ｄｕ｜）｜Ｄｕ｜＾ｐ－２Ｄｕ＋ｆ（ｘ,ｕ））＝Ｂ（ｘ,ｕ,Ｄｕ）在一定的条件下在Ｗ＾１．ｐ空间中的弱解的Ｈｏｌｄｅｒ连续性。     

Lp-Lq Estimates for a Linear Perturbed Klein-Gordon Equation

We consider L^p-L^q estimates for the solution u(t,x) to tbe following perturbed Klein-Gordon equation ∂_{tt}u - Δu + u + V(x)u = 0 \qquad x∈ R^n, n ≥ 3 u(x,0) = 0, ∂_tu(x,0) = f(x) We assume that the potential V(x) and the initial data f(x) are compact, and V(x) is sufficiently small, then the solution u(t,x) of the above problem satisfies ||u(t)||_q ≤ Ct^{-a}||f||_p for t > 1 where a is the piecewise-linear function of 1/p and 1/q.     

带不定线性部分椭圆方程的多解

给出增线性椭圆方程-△u=λV(x)u+f(x.u)在Ω上的一个非零解,其中Ω RN(N≥3)可以无界.并允许Ω=RN.V(x)可以变号,并通过截断技巧得到上述问题的一个非负解和一个非正解.     

MULTIPLE SOLUTIONS FOR THE SCHR?DINGER-POISSON EQUATION WITH A GENERAL NONLINEARITY

We are concerned with the nonlinear Schrodinger-Poisson equation{-△u+(V(x)-λ)u+φ(x)u = f(u),(P)-△ φ = u2,limx|→+∞ φ(x)= 0,x∈ R3,where λ is a parameter,V(x)is an...     

Schrödinger equations with unique positive isolated singularities

We investigate the class of nonnegative potentialsV(x) for which the Schrödinger equation ?Δu+V u=0 admits a unique type of singular solution such thatu(x)→∞ asx→0. This class includes the potentials with inverse-square growth at 0, i.e. 0≤V(x)≤C|x|^?2. If for instance we fix boundary datau=g at |x|=1 then the singular solution is unique up to a multiplicative factor.     

Homoclinic orbits for an unbounded superquadratic

We consider the following nonperiodic diffusion systems

一类临界增长非线性椭圆方程的解

利用非光滑临界点理论 ,本文证明了一类临界增长非线性椭圆方程-div(A(x ,u) ｜ u｜p-2 u) 1pA′u(x ,u) ｜ u｜p =g(x ,u) ｜u｜p -2 u ,u=0 ,　 Ω ; Ω 非平凡正解的存在性 .其中 1 相似文献   

Convergence of Iterative Difference Method with Nonuniform Meshes for Quasilinear Parabolic Systems

In this paper, we study the general difference schemes with nonuniform meshes for the following problem: u_t = A(x,t,u,u_x)u_{xx}, + f(x,t,u,u_x), 0 < x < l, 0 < t ≤ T \qquad (1) u(0,t) = u(l ,t) = 0, 0 < t ≤ T \qquad\qquad (2) u(x,0) = φ(x), 0 ≤ x ≤ l \qquad\qquad (3) where u, φ, and f are m-dimensional vector valued functions, u_t = \frac{∂u}{∂t}, u_x = \frac{∂u}{∂x}, u_{xx} = \frac{∂²u}{∂_x²}. In the practical computation, we usually use the method of iteration to calculate the approximate solutions for the nonlinear difference schemes. Here the estimates of the iterative sequence constructed from the iterative difference schemes for the problem (1)-(3) is proved. Moreover, when the coefficient matrix A = A(x, t, u) is independent of u_x, t he convergence of the approximate difference solution for the iterative difference schemes to the unique solution of the problem (1)-(3) is proved without imposing the assumption of heuristic character concerning the existence of the unique smooth solution for the original problem (1)-(3).     

一类非线性薛定谔方程的多解的存在性

本文讨论了如下一类非线性薛定谔方程：-△u＋V（x）u=f（u）,x∈R^N,在H^1（R^N）中无穷多解的存在性,其中N≥3,V（x）是RN上的实值连续函数并且满足对（A）x∈R^N,V（z）≥V0＞0.     

On Initial-boundary-value Problems for a Class of Systems of Quasi-linear Evolution Equations

In this paper the initial-boundary-value problems for pseudo-hyperbolic system of quasi-linear equations: {(-1)^Mu_{tt} + A(x, t, U, V)u_x^{2M}_{tt} = B(x, t, U, V)u_x^{2M}_{t} + C(x, t, U, V)u_x^{2M} + f(x, t, U, V) u_x^k(0,t) = ψ_{0k}(t), \quad u_x^k(l,t) = ψ_{lk}(t), \quad k = 0,1,…,M - 1 -u(x,0) = φ_0(x), \quad u_t(x,0) = φ_1(x) is studied, where U = (u_1, u_x,…,u_x^{2M - 1}) V = (u_t, u_{xt},…,u_x^{2M - 1_t}), A, B, C are m × m matrices, u, f, ψ_{0k}, ψ_{1k}, ψ_0, ψ_1 are m-dimensional vector functions. The existence and uniqueness of the generalized solution (in H² (0, T; H^{2M} (0, 1))) of the problems are proved.     

Solutions of a system of diffusion equations

We study existence and multiplicity of homoclinic type solutions to the following system of diffusion equations on \mathbbR ×W{\mathbb{R}} \times \Omega :