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1.
Summary I give a sufficient condition in order that a Dirichlet problem is solvable in H 2 (Ω) for a class of linear second order elliptic partial differential equations. Such a class includes some particular cases for which the result is known.
Sunto Si prova una condizione sufficiente affinchè un problema di Dirichlet sia risolubile in H 2 (Ω) per una classe di equazioni differenziali alle derivate parziali lineari ellittiche del secondo ordine. Tale classe comprende alcuni casi particolari per i quali il risultato è noto.


The present work was written while the author was a member of the ? Centro di Matematica e Fisica Teorica del C.N.R. ? at the University of Genova, directed by professorJ. Cecconi.

Entrata in Redazione il 25 febbraio 1971.  相似文献   

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In this article,we discuss that an oblique derivative boundary value problem for nonlinear uniformly elliptic complex equation of second order with the boundary conditions in a multiply connected unbounded domain D.The above boundary value problem will be called Problem P.Under certain conditions,by using the priori estimates of solutions and Leray-Schauder fixed point theorem,we can obtain some results of the solvability for the above boundary value problem(0.1) and(0.2).  相似文献   

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We study the behaviour of weak solutions (as well as their gradients) of boundary value problems for quasi-linear elliptic divergence equations in domains extending to infinity along a cone.  相似文献   

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This paper deals with the Dirichlet problem for second order linear elliptic equations in unbounded domains of the plane in weighted Sobolev spaces. We prove an a priori bound and an existence and uniqueness result.  相似文献   

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In some exterior domain G of the Euclidian p-space Rp the Dirichlet boundary value problem is considered for the equation (L + κ2)2u = f, where L is a uniformly elliptic operator and κ is a real number different from 0. It can be shown that each solution u of this equation splits into u = xl?lu1 + u2, where u1 and u2 satisfy Heimholte equations. Asymptotic conditions for u are formulated by imposing Sommerfeld radiation conditions on u1 and u2. If u1 and u2 are assumed to satisfy the same radiation condition, we prove a “Fredholm alternative theorem.” If u1 and u2 satisfy different radiation conditions, existence and uniqueness of the solution can be shown, provided the space dimension p is greater than 2.  相似文献   

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We prove existence and uniqueness of the solution of the Dirichlet problem for a class of elliptic equations in divergence form with discontinuous and unbounded coefficients in unbounded domains. Entrata in Redazione il 22 aprile 1999.  相似文献   

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We derive a Carleson type estimate for positive solutions of non-divergence second order elliptic equations Lu = a ij D ij u + b i D i u = 0 in a bounded domain Ω ⊂ ℝ n . We assume that b i L n (Ω) and Ω is a twisted H?lder domain of order α ∈ (1/2, 1] which satisfies a weak regularity condition. We also provide an example which shows that the main result fails in general if α ∈ (0, 1/2]. Bibliography: 18 titles.  相似文献   

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We prove the boundary Harnack principle for ratios of solutions u/v of non-divergence second order elliptic equations Lu = a ij D ij u + b i D i u = 0 in a bounded domain Ω ⊂  \mathbb R {\mathbb R} n . We assume that b i L n (Ω) and Ω is a twisted H?lder domain of order α ∈ (1/2, 1]. Based on this result, we derive the H?lder regularity of u/v for uniform domains. Bibliography: 27 titles.  相似文献   

10.
Analogues of the well known in the theory of analytic functions Phragmén-Lindelöff theorem are formulated for the solutions of a wide class of quasilinear equations of elliptic type. Examples are given which illustrate the sharpness of the obtained results for solutions of equations of the form div(|u|–2u)=f(x, u), where the function f(x, u) is locally bounded in IRn+1,f(x, 0)=0,uf(x, u)a¦u¦1+q,a>0,>1,-1>q0, n>/2.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 44, No. 2, pp. 279–283, February, 1992.  相似文献   

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Summary. In this paper, we study the spectral properties of Dirichlet problems for second order elliptic equation with rapidly oscillating coefficients in a perforated domain. The asymptotic expansions of eigenvalues and eigenfunctions for this kind of problem are obtained, and the multiscale finite element algorithms and numerical results are proposed. Mathematics Subject Classification (2000):65F10, 35P15This work is Supported by National Natural Science Foundation of China (grant # 19932030) and Special Funds for Major State Basic Research Projects (grant # TG2000067102)  相似文献   

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The paper gives some solvability conditions of the Dirichlet problem for the second order elliptic equation $$ - div(A(x)\nabla u) + (\bar b(x),\nabla u) - div(\bar c(x)u) + d(x)u = f(x) - divF(x),x \in Q,u|_{\partial Q} = u_0 \in L_2 (\partial Q) $$ in bounded domain Q ? R n (n ≥ 2) with smooth boundary ?QC 1. In particular, it is proved that if the homogeneous problem has only the trivial solution, then for any u 0L 2(?Q) and f, F from the corresponding functional spaces the solution of the non-homogeneous problem exists, from Gushchin’s space $ C_{n - 1} (\bar Q) $ and the following inequality is true: $$ \begin{gathered} \left\| u \right\|_{C_{n - 1} (\bar Q)}^2 + \mathop \smallint \limits_Q r\left| {\nabla u} \right|^2 dx \leqslant \hfill \\ \leqslant C\left( {\left\| {u_0 } \right\|_{L_2 (\partial Q)}^2 + \mathop \smallint \limits_Q r^3 (1 + |\ln r|)^{3/2} f^2 dx + \mathop \smallint \limits_Q r(1 + |\ln r|)^{3/2} |F|^2 dx} \right) \hfill \\ \end{gathered} $$ where r(x) is the distance from a point xQ to the boundary ?Q and the constant C does not depend on u 0, f and F.  相似文献   

15.
Denote by L a second order strongly elliptic operator in the Euclidian p-space Rp, and by P some real polynomial in one variable. First the wholespace-problem for the equation P(L)u = f is considered and asymptotic conditions are derived which yield an existence and uniqueness theorem. Then for the Dirichlet problem in some exterior domain G ? Rp a “Fredholm alternative theorem” is proved.  相似文献   

16.
The present paper deals with the mixed boundary value problem for elliptic equations with degenerate rank 0. We first give the formulation of the problem and estimates of solutions of the problem, and then prove the existence of solutions of the above problem for elliptic equations by the above estimates and the method of parameter extension. We use the complex method, namely first discuss the corresponding problem for degenerate elliptic complex equations of first order, afterwards discuss the above problem for degenerate elliptic equations of second order.  相似文献   

17.
In this paper we obtain Gaussian upper bounds for the integral kernel of the semigroup associated with second order elliptic differential operators with complex unbounded measurable coefficients defined in a domain Ω of ? N and subject to various boundary conditions. In contrast to the previous literature the diffusions coefficients are not required to be bounded or regular. A new approach based on Davies-Gaffney estimates is used. It is applied to a number of examples, including degenerate elliptic operators arising in Financial Mathematics and generalized Ornstein-Uhlenbeck operators with potentials.  相似文献   

18.
We study the Dirichlet problem, in Lipschitz domains and with boundary data in Besov spaces, for divergence form strongly elliptic systems of arbitrary order with bounded, complex-valued coefficients. A sharp corollary of our main solvability result is that the operator of this problem performs an isomorphism between weighted Sobolev spaces when its coefficients and the unit normal of the boundary belong to the space VMO.  相似文献   

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