Nonstationary Stokes equations in a half-space with continuous initial data

The paper is devoted to nonstationary Stokes equations in a half-space. The existence and uniqueness of a solution are proved in spaces of bounded or continuous functions. Estimates of solutions are given in the uniform norm and in the norms of Hölder spaces. Bibliography: 17 titles.__________Published in Zapiski Nauchnykh Seminarov POMI, Vol. 295, 2003, pp. 118–167.     

Time-periodic Stokes equations with inhomogeneous Dirichlet boundary conditions in a half-space

The time-periodic Stokes problem in a half-space with fully inhomogeneous right-hand side is investigated. Maximal regularity in a time-periodic L^p setting is established. A method based on Fourier multipliers is employed that leads to a decomposition of the solution into a steady-state and a purely oscillatory part in order to identify the suitable function spaces.     

Elliptic equations with BMO coefficients in Lipschitz domains

In this paper, we study inhomogeneous Dirichlet problems for elliptic equations in divergence form. Optimal regularity requirements on the coefficients and domains for the estimates are obtained. The principal coefficients are supposed to be in the John-Nirenberg space with small BMO semi-norms. The domain is supposed to have Lipschitz boundary with small Lipschitz constant. These conditions for the theory do not just weaken the requirements on the coefficients; they also lead to a more general geometric condition on the domain.

     

Elliptic equations with BMO coefficients in Reifenberg domains

The inhomogeneous Dirichlet problems concerning divergence form elliptic equations are studied. Optimal regularity requirements on the coefficients and domains for the W^1,p theory, 1 < p < ∞, are obtained. The principal coefficients are supposed to be in the John‐Nirenberg space with small BMO seminorms. The domain is a Reifenberg domain. These conditions for the W^1,p theory not only weaken the requirements on the coefficients but also lead to a more general geometric condition on the domains. In fact, these domains might have fractal dimensions. © 2004 Wiley Periodicals, Inc.     

Elliptic equations with measurable coefficients in Reifenberg domains

We prove W1,p estimates for elliptic equations in divergence form under the assumption that for each point and for each sufficiently small scale there is a coordinate system so that the coefficients have small oscillation in (n−1) directions. We assume the boundary to be δ-Reifenberg flat and the coefficients having small oscillation in the flat direction of the boundary.     

Elliptic equations with BMO nonlinearity in Reifenberg domains

Given p∈[2,+∞), we obtain the global W1,p estimate for the weak solution of a boundary-value problem for an elliptic equation with BMO nonlinearity in a Reifenberg domain, assuming that the nonlinearity has sufficiently small BMO seminorm and that the boundary of the domain is sufficiently flat.     

Initial-boundary value problems for the Vlasov-Poisson equations in a half-space

We consider initial-boundary value problems for the Vlasov-Poisson equations in a half-space that describe evolution of densities for ions and electrons in a rarefied plasma. For sufficiently small initial densities with compact supports and large strength of an external magnetic field, we prove the existence and uniqueness of classical solutions for initial-boundary value problems with different boundary conditions for the electric potential: the Dirichlet conditions, the Neumann conditions, and nonlocal conditions.     

Elliptic equations strongly degenerate at a point

In this paper we will mainly propose some problems for a class of degenerate elliptic equations, either linear or nonlinear. We will study some special cases of these problems and reveal some phenomena which may not have been noticed previously.     

Elliptic second order equations

Preface: These notes correspond to a series of lectures I was invited to deliver by the Accademia dei Lincei at the Politecnico de Milano in April 1987. Most of the material here presented is unpublished research, and in this context I would like to thank E. B. Fabes, P. L. Lions, L. Nirenberg and S. Salsa for many challenging discussions. I also would like to thank C. Pagani and S. Salsa for their help in clarifying both the oral and written version of these lectures while they were prepared and delivered. Finally, through Professor L. Amerio, I would like to thank all of my Italian colleagues that made my stay in Milano so scientifically interesting and at the same time so pleasant.     

Elliptic binomial diophantine equations

The complete sets of solutions of the equation are determined for the cases , , , , , , , . In each of these cases the equation is reduced to an elliptic equation, which is solved by using linear forms in elliptic logarithms. In all but one case this is more or less routine, but in the remaining case () we had to devise a new variant of the method.

     

Elliptic equations with vertical asymptotes in the nonlinear term

We study the existence of solutions of the nonlinear problem {fx349-1} where μ is a bounded measure andg is a continuous nondecreasing function such thatg(0)=0. In this paper, we assume that the nonlinearityg satisfies {fx349-2} Problem (0.1) need not have a solution for every measure μ. We prove that, given μ, there exists a “closest” measure μ^* for which (0.1) can be solved. We also explain how assumption (0.2) makes problem (0.1) different from the case whereg(t) is defined for everyt ∈ ℝ.     

Elliptic equations with jumping nonlinearities involving high eigenvalues

We present some multiplicity results concerning semilinear elliptic Dirichlet problems with jumping nonlinearities where the jumping condition involves a set of high eigenvalues not including the first one. Using a variational method we show that the number of solutions may be arbitrarily large provided the number of jumped eigenvalues is large enough. Indeed, we prove that for every positive integer $k$ there exists a positive integer $n(k)$ such that, if the number of jumped eigenvalues is greater than $n(k),$ then the problem has at least a solution which presents $k$ peaks. Moreover, we describe the asymptotic behaviour of the solutions as the number of jumped eigenvalues tends to infinity; in particular, we analyse some concentration phenomena of the peaks (near points or suitable manifolds), we describe the asymptotic profile of the rescaled peaks, etc $\ldots $      

Solvability of general boundary-value problems in a half-space for inhomogeneous differential equations with constant coefficients

We present sufficient conditions for the existence of solutions of general boundary-value problems in a half-space for inhomogeneous differential equations with constant coefficients and arbitrary boundary data in the space of tempered distributions.