arXiv subjects

Abbas Moameni

Publications and source records attributed to Abbas Moameni.

26 records · Page 2Linked to original sources

arXiv2007

Schrodinger equations and Hamiltonian systems of PDEs with selfdual boundary conditions

Selfdual variational calculus is further refined and used to address questions of existence of local and global solutions for various parabolic semi-linear equations, Hamiltonian systems of PDEs, as well as certain nonlinear Schrodinger evolutions. This allows for the resolution of such equations under general time boundary conditions which include the more traditional ones such as initial value problems, periodic and anti-periodic orbits, but also yield new ones such as "periodic orbits up to an isometry" for evolution equations that may not have periodic solutions. In the process, we introduce a method for perturbing selfdual functionals in order to induce coercivity and compactness, while keeping the system selfdual.

math.AP↗

arXiv2007

Anti-symmetric Hamiltonians (II): Variational resolutions for Navier-Stokes and other nonlinear evolutions

The nonlinear selfdual variational principle established in a preceeding paper [8] -- though good enough to be readily applicable in many stationary nonlinear partial differential equations -- did not however cover the case of nonlinear evolutions such as the Navier-Stokes equations. One of the reasons is the prohibitive coercivity condition that is not satisfied by the corresponding selfdual functional on the relevant path space. We show here that such a principle still hold for functionals of the form I(u)= \int_0^T \Big [ L (t, u(t),\dot {u}(t)+Λu(t)) +< Λu(t), u(t) > \Big ] dt +\ell (u(0)- u(T), \frac {u(T)+ u(0)}{2}) where $L$ (resp., $\ell$) is an anti-selfdual Lagrangian on state space (resp., boundary space), and $Λ$ is an appropriate nonlinear operator on path space. As a consequence, we provide a variational formulation and resolution to evolution equations involving nonlinear operators such as the Navier-Stokes equation (in dimensions 2 and 3) with various boundary conditions. In dimension 2, we recover the well known solutions for the corresponding initial-value problem as well as periodic and anti-periodic ones, while in dimension 3 we get Leray solutions for the initial-value problems, but also solutions satisfying $u(0)=αu(T)$ for any given $α$ in $(-1,1)$. Our approach is quite general and does apply to many other situations.

math.AP↗

arXiv2006

Existence of soliton solutions for a quasilinear Schrödinger equation involving critical exponent in ${\BR}^N$}

Mountain pass in a suitable Orlicz space is employed to prove the existence of soliton solutions for a quasilinear Schrödinger equation involving critical exponent in ${\BR}^N$. These equations contain strongly singular nonlinearities which include derivatives of the second order. Such equations have been studied as models of several physical phenomena. The nonlinearity here corresponds to the superfluid film equation in plasma physics.

math.AP↗

arXiv2006

Existence and nonexistence of solutions for a singular $p$-Laplacian Dirichlet problem

We study the existence of positive radially symmetric solution for the singular $p$-Laplacian Dirichlet problem, $-\bigtriangleup_p u =λ|u|^{p-2} u-γu^{-α}$ where $λ>0,γ>0$ and, $0<α<1$, are parameters and $Ω$, the domain of the equation, is a ball in $\mathbb{R}^N$. By using some variational methods we show that, if $λ$ is contained in some interval, then the problem has a radially symmetric positive solution on the ball. Moreover, we obtain a nonexistence result, whenever $λ\leq 0, γ<0$ and $Ω$ is a bounded domain, with smooth boundary.

math.AP↗

arXiv2006

On a class of periodic quasilinear Schrödinger equations involving critical growth in ${\BR}^2$

We consider the equation $- Δu+V(x)u- k(\Del(|u|^{2}))u=g(x,u), u>0, x \in {\BR}^2,$ where $V:{\BR}^2\to {\BR}$ and $g:{\BR}^2 \times {\BR}\to {\BR}$ are two continuous $1-$periodic functions. Also, we assume $g$ behaves like $\exp (β|u|^4)$ as $|u|\to \infty.$ We prove the existence of at least one weak solution $u \in H^1({\BR}^2)$ with $u^2 \in H^1({\BR}^2).$ Mountain pass in a suitable Orlicz space together with Moser-Trudinger are employed to establish this result. Such equations arise when one seeks for standing wave solutions for the corresponding quasilinear Schrödinger equations. Schrödinger equations of this type have been studied as models of several physical phenomena. The nonlinearity here corresponds to the superfluid film equation in plasma physics.

math.AP↗

arXiv2006

Soliton solutions for quasilinear Schrödinger equations involving supercritical exponent in $R^N$

We study the existence of positive solutions to the quasilinear elliptic problem -εΔu+V(x)u-εk(\Del(|u|^{2}))u=g(u), \quad u>0, x \in R^N, where g has superlinear growth at infinity without any restriction from above on its growth. Mountain pass in a suitable Orlicz space is employed to establish this result. These equations contain strongly singular nonlinearities which include derivatives of the second order which make the situation more complicated. Such equations arise when one seeks for standing wave solutions for the corresponding quasilinear Schrödinger equations. Schrödinger equations of this type have been studied as models of several physical phenomena. The nonlinearity here corresponds to the superfluid film equation in plasma physics.

math.AP↗

arXiv2005

Selfdual Variational Principles for Periodic Solutions of Hamiltonian and Other Dynamical Systems

Selfdual variational principles are introduced in order to construct solutions for Hamiltonian and other dynamical systems which satisfy a variety of linear and nonlinear boundary conditions including many of the standard ones. These principles lead to new variational proofs of the existence of parabolic flows with prescribed initial conditions, as well as periodic, anti-periodic and skew-periodic orbits of Hamiltonian systems. They are based on the theory of anti-selfdual Lagrangians introduced and developed recently in [3], [4] and [5].

math.AP↗

arXiv2005

On the existence of Hamiltonian paths connecting Lagrangian submanifolds

We use a new variational method --based on the theory of anti-selfdual Lagrangians developed in [2] and [3]-- to establish the existence of solutions of convex Hamiltonian systems that connect two given Lagrangian submanifolds in $\R^{2N}$. We also consider the case where the Hamiltonian is only semi-convex. A variational principle is also used to establish existence for the corresponding Cauchy problem. The case of periodic solutions will be considered in a forthcoming paper [5].

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