1,720,999 research outputs found

    Phase transition problems with the line tension effect: the super-quadratic case

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    Let Ω\Omega be an open bounded set of R3\mathbb{R}^3 and let WW and VV be two non-negative continuous functions vanishing at α,β\alpha, \beta and α,β\alpha', \beta', respectively. We analyze the asymptotic behavior as ε0\varepsilon \to 0, in terms of Γ\Gamma-convergence, of the following functional Fε(u):=εp2 ⁣Ω ⁣Dupdx+1εp2p1 ⁣Ω ⁣W(u)dx+1ε ⁣Ω ⁣V(Tu)dH2   (p>2), F_{\varepsilon}(u):=\varepsilon^{p-2}\!\int_{\Omega}\!|Du|^pdx+\frac{1}{\varepsilon^{\frac{p-2}{p-1}}}\!\int_{\Omega}\!W(u)dx+\frac{1}{\varepsilon}\!\int_{\partial\Omega}\!V(Tu)d\mathcal{H}^2 \ \ \ (p>2), where uu is a scalar density function and TuTu denotes its trace on Ω\partial\Omega. We show that the singular limit of the energies FεF_{\varepsilon} leads to a coupled problem of bulk and surface phase transitions

    Subcritical approximation of the Sobolev quotient and a related concentration result

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    Let Ω\Omega be a general, possibly non-smooth, bounded domain of RN\mathbb{R}^N, N3N\geq 3. Let 2 ⁣ ⁣= ⁣2N ⁣/(N2)\displaystyle 2^{*}\!\!=\!{2N}\,\!/{(N-2)} be the critical Sobolev exponent. We study the following variational problem Sε=sup{Ωu2 ⁣εdx:Ωu2dx1,u=0 on Ω}, S^{*}_{\varepsilon}=\sup\left \{ \int_{\Omega}|u|^{2^{*}\!-\varepsilon}dx: \int_{\Omega}|\nabla u|^{2}dx\leq 1, u=0 \ \text{on} \ \partial\Omega \right \}, investigating its asymptotic behavior as ε\varepsilon goes to zero, by means of \gamp-convergence techniques. We also show that sequences of maximizers uεu_\varepsilon concentrate energy at one point x0Ωx_0\in \overline{\Omega}

    The Dirichlet problem for the p-fractional Laplace equation

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    We deal with a class of equations driven by nonlocal, possibly degenerate, integro-differential operators of differentiability order s in (0,1) and summability growth p in (1,infty), whose model is the fractional p-Laplacian operator with measurable coefficients. We review several recent results for the corresponding weak solutions/supersolutions, as comparison principles, a priori bounds, lower semicontinuity, boundedness, Hölder continuity up to the boundary, and many others. We then discuss the good definition of (s,p)-superharmonic functions, and the nonlocal counterpart of the Perron method in nonlinear Potential Theory, together with various related results. We briefly mention some basic results for the obstacle problem for nonlinear integro-differential equations. Finally, we present the connection amongst the fractional viscosity solutions, the weak solutions and the aforementioned (s,p)-superharmonic functions, together with other important results for this class of equations when involving general measure data, and a surprising fractional version of the Gehring lemma. We sketch the corresponding proofs of some of the results presented here, by especially underlining the development of new fractional localization techniques and other recent tools. Various open problems are listed throughout the paper

    Developments and perspectives in Nonlinear Potential Theory

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    Nonlinear Potential theory aims at replicating the classical linear potential theory when nonlinear equations are considered. In recent years there has been a substantial development of this subject, mostly linked to the possibility of proving pointwise estimates for solutions to nonlinear equations via linear and nonlinear potentials. Here we give a brief account of such developments and outline the connections with different fields

    Γ-Convergence of some super quadratic functionals with singular weights

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    We study the Γ\Gamma-convergence of the following functional (p>2p>2) Fε(u):=εp2 ⁣Ω ⁣Dupd(x,Ω)adx+1εp2p1 ⁣Ω ⁣W(u)d(x,Ω)ap1dx+1ε ⁣Ω ⁣V(Tu)dH2, F_{\varepsilon}(u):=\varepsilon^{p-2}\!\int_{\Omega}\!|Du|^p d(x,\partial \Omega)^{a}dx+\frac{1}{\varepsilon^{\frac{p-2}{p-1}}}\!\int_{\Omega}\!W(u) d(x,\partial \Omega)^{-\frac{a}{p-1}}dx+\frac{1}{\sqrt{\varepsilon}}\!\int_{\partial\Omega}\!V(Tu)d\mathcal{H}^2, where Ω\Omega is an open bounded set of R3\mathbb{R}^3 and WW and VV are two non-negative continuous functions vanishing at α,β\alpha, \beta and α,β\alpha', \beta', respectively. In the previous functional, we fix a=2pa=2-p and uu is a scalar density function, TuTu denotes its trace on Ω\partial\Omega, d(x,Ω)d(x,\partial \Omega) stands for the distance function to the boundary \partial\Om. We show that the singular limit of the energies FεF_{\varepsilon} leads to a coupled problem of bulk and surface phase transitions

    Gamma-convergence for one-dimensional nonlocal phase transition energies

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    We study the asymptotic behavior as ε goes to 0 of an appropriate scaling of the following nonlocal Allen-Cahn energy,where I is an interval in R, and W is a double-well potential. We provide a Γ-convergence result for any s ∈ (0,1), by extending the case when s=1/2 studied by Alberti, Bouchittè and Seppecher in [2]. We also investigate the convergence as s↗1 of the related optimal profile problem to the local counterpart

    Nonlinear parabolic problems with lower order terms and related integral estimates

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    We deal with the solutions to nonlinear parabolic equations of the form utdiva(x,t,Du)+g(x,t,u)=f(x,t)onΩT=Ω×(T,0), u_t-div a(x,t,Du)+g(x,t,u)=f(x,t) on \Omega_T=\Omega\times(-T,0), under standard growth conditions on gg and aa, with ff only assumed to be integrable to the power γ>1\gamma > 1. We prove general local decay estimates for level sets of the solutions uu and the gradient DuDu which imply very general estimates in rearrangement function spaces (Lebesgue, Orlicz, Lorentz) and non-rearrangement ones, up to Lorentz–Morrey spaces

    Fractional Regularity for Nonlinear Elliptic Problems with Measure Data

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    We consider nonlinear elliptic equations of the type diva(x,Du)=μ-\text{\rm div}\,a(x, Du)=\mu having a Radon measure on the right-hand side and prove fractional differentiability results of Calder\'on-Zygmund type for very weak solutions. We extend some of the results achieved by G. Mingione (Ann. Scu. Norm. Sup., 2007), in turn improving a regularity result by Cirmi \& Leonardi (DCDS-A, 2010)
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