arXiv subjects

Fouad Et-tahri

Publications and source records attributed to Fouad Et-tahri.

5 recordsLinked to original sources

arXiv2026

Control of the Fisher-Stefan system

This paper addresses the exact controllability of trajectories in the one-dimensional Fisher-Stefan problem--a reaction-diffusion equation that models the spatial propagation of biological, chemical, or physical populations within a free-end domain, governed by Stefan's law. We establish the local exact controllability to the trajectories by reformulating the problem as the local null controllability of a nonlinear system with distributed controls. Our approach leverages the Lyusternik-Graves theorem to achieve local inversion, leading to the desired controllability result. Finally, we illustrate our theoretical findings through several numerical experiments based on the Physics-Informed Neural Networks (PINNs) approach.

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arXiv2026

Averaged Controllability of Time-Fractional Schrödinger Equations with Random Quantum Diffusivity

This paper addresses the problem of averaged controllability for the time-fractional Schrodinger equation, where the quantum diffusivity parameter is a random variable with a general probability distribution. First, by exploiting the analyticity of the Mittag-Leffler function and Muntz's theorem, we show that the simultaneous null controllability of the system can occur only for a countable set of realizations of the random diffusivity. In particular, this implies the impossibility of simultaneous null controllability for absolutely continuous random diffusivity. Next, we prove the lack of exact averaged controllability for absolutely continuous random variables, irrespective of the control time. Furthermore, we introduce a new two-parameter fractional characteristic function, which allows us to construct a class of random variables satisfying null averaged controllability at any time from any arbitrary sensor set of positive Lebesgue measure. This is achieved using an open-loop control belonging to L^\infty and independent of the random parameter. In particular, we obtain the null controllability of the fractional biharmonic diffusion equation. Finally, we conclude with several remarks and open problems that merit future investigation.

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arXiv2024

Insensitizing controls of a volume-surface reaction-diffusion equation with dynamic boundary conditions

This paper deals with the insensitizing controllability property of the quasilinear parabolic equation with dynamic boundary conditions. This problem can be reformulated as a null controllability problem for a cascade quasilinear system with dynamic boundary conditions. To this end, we approach the problem by first dealing with null controllability in the framework of an inhomogeneous linearized system. Next, we derive new estimates of control and state, allowing us to apply a local inversion theorem to obtain null controllability of the quasilinear system.

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arXiv2024

Null controllability of an ODE-heat system with coupled boundary and internal terms

This paper is devoted to the theoretical and numerical analysis of the null controllability of a coupled ODE-heat system internally and at the boundary with Neumann boundary control. First, we establish the null controllability of the ODE-heat with distributed control using Carleman estimates. Then, we conclude by the strategy of space domain extension. Finally, we illustrate the analysis with some numerical experiments.

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arXiv2023

On uniform null-controllability of tangential transport-diffusion equations with vanishing viscosity limit

This paper aims to address an interesting open problem posed in the paper ''Singular Optimal Control for a Transport-Diffusion Equation'' of Sergio Guerrero and Gilles Lebeau in 2007. The problem involves studying the null-controllability cost of a transport-diffusion equation with Neumann conditions. Our objective is twofold. Firstly, we investigate the scenario where each trajectory of the tangential velocity enters the control region in a shorter time at a fixed entry time. By employing Agmon inequalities and Carleman estimates, we establish that the control cost remains bounded for sufficiently small diffusivity and large control time. Secondly, we explore the case where at least one trajectory fails to enter the control region. In this scenario, we prove that the control cost explodes exponentially when the diffusivity approaches zero and the control time is sufficiently small.

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