Existence of solutions for a class of singular quasilinear elliptic resonance problems

The paper concerns a resonance problem for a class of singular quasilinear elliptic equations in weighted Sobolev spaces. The equation set studied is one of the most useful sets of Navier-Stokes equations; these describe the motion of viscous fluid substances such as liquids, gases and so on. By using Galerkin-type techniques, the Brouwer fixed point theorem, and a new weighted compact Sobolev-type embedding theorem established by Shapiro, we show the existence of a nontrivial solution.     

Existence and multiplicity of weak solutions for a singular semilinear elliptic equation

In this paper we study existence and multiplicity of weak solutions of the homogenous Dirichlet problem for a singular semilinear elliptic equation with a quadratic gradient term. The proofs for the main results are based on a priori estimates of solutions of approximate problems.     

Existence and multiplicity of positive solutions for singular quasilinear problems

In this work we combine perturbation arguments and variational methods to study the existence and multiplicity of positive solutions for a class of singular p-Laplacian problems. In the first two theorems we prove the existence of solutions in the sense of distributions. By strengthening the hypotheses, in the third and last result, we establish the existence of two ordered positive weak solutions.     

Existence and multiplicity of positive solutions for classes of singular elliptic PDEs

We consider the boundary value problem

     

Existence and multiplicity of solutions for elliptic problems with indefinite discontinuous nonlinearities

In this paper we study the critical points for a locally Lipschitz functional that in some sense will be solutions of an elliptic problem with indefinite discontinuous nonlinearities. We should mention that our results were inspired by the work of Ambrosetti-Badiale [3], Arcoya-Calahorrano [5], Alama-Tarantello [1] and Chang [8]. For the problem studied in [3] we introduce indefinite nonlinearities as in [1] and [6]. To obtain the existence and multiplicity of solutions we use the critical points theory developed by Chang. Applications for Plasma Physics are considered with nonlinearities that change sign. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Existence of three solutions for a class of elliptic eigenvalue problems

In this paper, we consider a problem of the type −Δu = λ(f(u) + μg(u)) in Ω, u¦∂Ω = 0, where Ω Rⁿ is an open-bounded set, f, g are continuous real functions on R, and λ, μ ε R. As an application of a new approach to nonlinear eigenvalues problems, we prove that, under suitable hypotheses, if ¦μ¦ is small enough, then there is some λ > 0 such that the above problem has at least three distinct weak solutions in W₀^1,2(Ω).     

Existence and multiplicity of homoclinic solutions for a class of damped vibration problems

The main purpose of this paper is to study the following damped vibration problems

(1.1)     

Existence implies uniqueness for a class of singular anisotropic elliptic boundary value problems

We consider a singular anisotropic quasilinear problem with Dirichlet boundary condition and we establish two sufficient conditions for the uniqueness of the solution, provided such a solution exists. The proofs use elementary tools and they are based on a general comparison lemma combined with the generalized mean value theorem. Copyright © 2001 John Wiley & Sons, Ltd.     

Existence and multiplicity of weak solutions for elliptic Dirichlet problems with variable exponent

Under appropriate growth conditions on the nonlinearity, the existence of multiple solutions for nonlinear elliptic Dirichlet problems with variable exponent is established. The approach is based on variational methods. Some applications and examples illustrate the obtained results.     

Existence and multiplicity of solutions for critical elliptic equations with multi-polar potentials in symmetric domains

In this paper, we consider the elliptic equations with critical Sobolev exponents and multi-polar potentials in bounded symmetric domains and prove the existence and multiplicity of symmetric positive solutions by using the Ekeland variational principle and the Lusternik–Schnirelmann category theory.     

Existence and multiplicity of positive solutions for a class of singular Kirchhoff type problems with sign‐changing potential

In this paper, the existence and multiplicity of positive solutions are obtained for a class of Kirchhoff type problems with two singular terms and sign‐changing potential by the Nehari method.     

Existence and multiplicity of solutions for semilinear elliptic systems

In this article, it is considered the existence of nonzero solutions for a semilinear elliptic system. First, the existence of one nonzero solution is obtained by applying a version of the generalized mountain pass theorem. Next, a maximum principle is used to derive the existence of a positive and a negative solution. Finally, the generalized Morse theory is used to provides the exist ence of at least three nonzero solutions when the primitive of the nonlinearity has a superquadratic behaviour at infinity.Research partially supported by CNPq/Brazil.     

Existence and multiplicity of positive radial solutions for singular superlinear elliptic systems in the exterior of a ball

We prove the existence and multiplicity of positive radial solutions to the nonlinear system

$\{\begin{array}{c}\hfill ?\mathrm{\Delta }{u}_i=\lambda K_i(|x|)f_i(u_j)\text{ in }\mathrm{\Omega },\hfill \\ \hfill d_i\frac{?u_i}{?n}+{\stackrel{?}{c}}_i(u_i)u_i=0\text{ on }|x|=r_0,\hfill \\ \hfill u_i(x)\to 0\text{ as }|x|\to \infty ,\hfill \end{array}$

for a certain range of $\lambda >0$, where $i,j\in \{1,2\},i\ne j$, $\mathrm{\Omega }=\{x\in {\mathbb{R}}^N:|x|>r_0>0\}$, $N>2,d_i\ge 0$, $K_i:[r_0,\infty )\to (0,\infty )$, $\stackrel{?}{c}:[0,\infty )\to [0,\infty ),f_i:(0,\infty )\to \mathbb{R}$ are continuous with possible singularity ±∞ at 0 and satisfy a combined superlinear condition at ∞.