具有共振的边值问题解的存在性

利用Mawhin的重合度理论,研究具有共振的n-阶m-点边值问题x~((n))(t)=f(t,x(t),x′(t),…,x~((n-1))(t)),t∈(0,1)x(0)=x(η),x′(0)=x″(0)=…=x~((n-2))(0)=0,x~((n-1))(1)=α_ix~((n-1))(ξ_i)解的存在性,其中n≥2,m≥3,f:[0,1]×R~n→R将有界集映为有界集,且当x(t)∈C~(n-1)[0,1]时,f(t,x(t),x′(t),…,x~((n-1))(t))∈L~1[0,1],0<ξ_1<ξ_2<…<ξ_(m-2)<1,0<η<1,α_i∈R.在这里并不要求f具有连续性.     

拟线性抛物方程组第一边界问题的有限差分法

本文利用有限差分法来作出拟线性抛物方程组u_t=(-1)^M+1A(x,t,u…,u_x^M-1)u_x^2M+F(x,t,u,…,u_x^2M-1) (1)具有齐次边界条件u_xk(0,t)=u_xk(l,t)=0 (k=0,1,…,M-1) (2)与初始条件u(x,0)=φ(x) (3)在矩形区域Q_T={0≤x≤l,0≤t≤T}上的解,其中u=(u₁,…,u_m),φ(x)与F为m维向量值函数,A为m×m正定矩阵。证明了问题(1),(2)与(3)的一类相当广泛的有限差分格式的解的收敛性。所得向量值极限函数u(x,t)∈W₂^2M,1(Q_T)是问题(1),(2),(3)的唯一广义整体解。     

非线性项有非线性增长的2阶泛函微分方程边值问题

本文考虑下述２阶泛函微分方程边值问题：x″(t)=f(t,x_t,x′(t))(00=φ,x(b)=B.对于ｆ有非线性增长的情况，得出了上述问题可解的某些充分条件。     

关于非线性泛函的一个问题

Suppose that H is a Hilbert space, D is a convex closed set inis a functioal, f(x)=1/2‖x‖²-g(x). Suppose that the minimum of f(x) withrespect to D is attained at x₀∈D and f(x) has a bounded linear Gateaux differential at x₀. In this paper we prove that f(x₀) is a critical value of f(x) when and only when g′(x₀)∈I_D(x₀)={(1-λ)x₀+λy|y∈D.λ≥0}.     

一类非线性波方程初边值问题解的爆破

该文研究如下具有非线性阻尼项和非线性源项的波方程的初边值问题 u_tt -u_xxt -u_xx -(σ(u²_x)u_x)_x+δ|u_t|^p-1u_t=μ|u|^q-1u, 0 < x <1, 0≤ t ≤T, (0.1) u(0, t)=u(1, t)=0, 0≤t≤ T, (0.2) u(x, 0)=u₀(x), u_t(x, 0)=u₁(x),0≤x≤1.(0.3) 文章将给出问题(0.1)--(0.3)的解在有限时刻爆破的充分条件, 同时将证明问题的局部广义解和局部古典解的存在性和唯一性.     

拟线性抛物方程组第一边界问题的有限差分法 ——Ⅲ.稳定性

讨论如下拟线性抛物组第一边值问题的显式、弱隐式和强隐式差分解u_t=(-1)^M+1A(x,t,u,…,u_x^M-1)u_x^2M+f(x,t,u,…,u_x^2M-1(x,t)∈Q_T={O<x<l,0<t≤T.}，u_x^k(0，t)=u_x^k(l，t)=0 (k=0，1，…，M -1)，0<t≤T，u(x，0)=φ(x)，0≤x≤l，其中u，φ和f是m维向量值函数，A是m×m正定矩阵，u_t=∂u/∂t，u_x^k=∂^ku/∂x^k.在以下意义下证明了该问题的一般有限差分格式的稳定性：即离散向量解在W₂^(2M，M)(Q_T)中的离散范数是连续地依赖于初始数据的H^M离散范数，以及矩阵A与自由项f的相应的离散范数.     

多元Szász—Mirkjan算子的一致逼近

本文研究了多元Szása—Mirakjan算子在C_2B(T)中的逼近性质,利用K—泛函,建立了等价的逼近定理.主要结果如下 定理设f∈C_2B(T),0a) ;(ii)‖S_n,m(f)-f‖_∞ =0(n^-a);(iii)a)‖f(x+tφ(x),y)-2f(x,y)+f(x-tφ(x),y)‖_∞ =0(t<     

Duffing型方程解的有界性

证明了下列Duffing型方程的所有解的有界性 :d2x / dt2 +x²ⁿ⁺¹+Σ²ⁿ_j=0 x^jp^j(t) =0 ,n≥1,其中,p1,p2 ,… ,p2n是 1周期的有Lipschitz连续性的函数,p_n+1,… ,p2n是Zygmund连续的 .这表明Duffing型方程的解的有界性不必要求pj(t)的光滑性.     

用Hermite-Fejér型插值多项式逼近连续函数

Let f(x)∈C_[-1,1],T_n(x)=cos (n arccos x),U_n(x)=(sin((n+1)arccosx))/(1-x²)^1/2,P_n(x) be the Legendre polynomials of degree n. And let ω(t ) be a given modulus of continuity, H_ω={f|ω(f,t)≤ω(t)}.A. K. Sharma and J. Tzimbalario(J. Appro. Th., 13(1975), 431-442) considered the operators L_n,p (f, x) (p= 0, 1, 2,3) and obtained some theorems.In this paper, we prove the following theorems.     

RIGHT FOCAL BOUNDARY VALUE PROBLEM WITH SINGULARITY

This article proves existence results for singular problem (-1)^n-px⁽ⁿ⁾(t)=f(t, x(t), ..., x^(n-1)(t)), for 0(i)(0)=0, i=1, 2, ..., p-1, x⁽ⁱ⁾(1)=0, i=p, p+1, ... , n-1. Here the positive Carathedory function f may be singular at the zero value of all its phase variables. The interesting point is that the degrees of some variables in the nonlinear term f(t, x₀, x₁, ..., x_n-1) are allowable to be greater than 1. Proofs are based on the Leray-Schauder degree theory and Vitali's convergence theorem. The emphasis in this article is that f depends on all higher-order derivatives. Examples are given to illustrate the main results of this article.     

具强吸引项的非线性反应扩散方程的解的全局熄灭问题

设ｆ定义在［０，＋∞）上的非负值连续凹函数并满足．本文证明了对于这类函数ｆ而言，反应扩散方程ｕｔ＝△ｕ－ｆ（ｕ）的初值问题和具有齐次边值条件的初边值问题的解将在有限时刻全局熄灭，并给出了全局熄灭的时间估计．     

A modified quasi-boundary value method for ill-posed problems

In this paper, we study a final value problem for first order abstract differential equation with positive self-adjoint unbounded operator coefficient. This problem is ill-posed. Perturbing the final condition we obtain an approximate nonlocal problem depending on a small parameter. We show that the approximate problems are well posed and that their solutions converge if and only if the original problem has a classical solution. We also obtain estimates of the solutions of the approximate problems and a convergence result of these solutions. Finally, we give explicit convergence rates.     

BOUNDARY VALUE PROBLEMS WITH INTEGRO CONDITION FOR RETARDED FUNCTIONAL DIFFERENTIAL EQUATIONS

1 IntroductionIn recent years) there were many results of studying boundary value problemsfor functional differential equations [1-5]. But the boundary conditions are allDirichlet's type. In this paper, we will study a kind of boundary value problemswitb integro boundary condition fOr the functional differential equdtionswhere f(t, yt, x, y) is a continuous real function defined on the set fl = [0, T] xC. x R', and is continuously differentiable with respect to each variable x, y;p E C. = C…     

BOUNDARY VALUE PROBLEMS FOR nTH ORDER RETARDED FUNCTIONAL DIFFERENTIAL EQUATIONS

1IntroductionTherearemanyresultsofstudyingboundaryvalueproblemsforsecondorderfunctionaldifferentialequations['I'].Butthestudyofboundaryvalueproblemsforhigherorderfunctionaldifferentialequationsrarelyappears.Inthispaper,wediscussthefollowingntypesofboundaryvalueproblemsforniborderfunctionaldifferentialequationswheref(t,yi,xo3xl)'',x.--1)isacontinuousrealfunctiondefinedonthesetA=[0,T]xCdxR".Forafixedr>0,letCrgC([--r,0],R)bethespaceofcontinuousfunctionon[--r,0]withthenormdefinedbyIIWll=supl…     

三阶RFDE边值问题

本文继续研究三阶RFDE边值问题，得到了解的存在唯一性的新的结果。     

Nonlinearity identification in divergence type elliptic boundary value problems

The identification of the nonlinearity in the equation

     

Mixed boundary value problem for some pairs of metaanalytic function and analytic function

In this article, some mixed boundary value problems (BVPs) on the unit circumference for some pairs of a metaanalytic function and an analytic function are discussed. Using the relationship between metaanalytic function and polyanalytic function, the expression of solution and the condition of solvability for the problem are obtained by reducing the problem to an equivalent system of a Haseman BVP for analytic function and a Hilbert BVP for analytic function. Copyright © 2008 John Wiley & Sons, Ltd.     

A symmetry problem from probability

We examine solutions of two related boundary value problems for smooth domains in Euclidean space which arise from variational problems in probability. We show that the existence of solutions to each problem implies that the domain is a sphere.

     

Some existence results for differential equations of second order

Existence results for initial value problem and Dirichlet boundary value problem for nonlinear differential equations of second order are obtained.