# Modélisation, observation et commande d’une classe d’équations aux dérivées partielles : application aux matériaux semi-transparents

Abstract : This thesis investigates the theoretical and numerical analysis of coupled radiative conductive heat transfer in a semi-transparent, gray and non-scattering 2D medium. This two heat transfer modes are described by the radiative transfer equation (RTE) and the nonlinear heat equation (NHE). We proved the existence and uniqueness of the solution of coupled systems with homogeneous Dirichlet boundary conditions using the fixed-point theorem. Moreover, we developed a useful algorithm to simulate the temperature in the medium. We used the quadrature $S_{N}$ for the angular discretization of the RTE. The spatial discretization of RTE was made by the discontinuous Galerkin method (DG) and the finite element method for the non-linear heat equation. We have shown the convergence and the stability of the coupled numerical scheme using the discrete fixed point. The discrète model obtained after an approximation allowed us to do the analysis and synthesis of state estimators and feedback control design for stabilization of the system. Thanks to the special structure of the model and using the Differential Mean Value Theorem (DMVT), we proposed a reduced order observer and we construct a gain matrix, which ensures the exponential stability of the proposed observer and guarantees the boundedness of the estimate vector. An extension to $\mathcal{H}_{\infty}$ filtering is also provided. We have extended the reduced order approach in the case of the observer-based controller and we proved the exponential stability under the control feedback law. Similarly, an extension to $\mathcal{H}_{\infty}$ filtering is also provided. The obtained results were validated through several numerical simulations.
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Submitted on : Thursday, March 29, 2018 - 1:27:54 PM
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• HAL Id : tel-01751836, version 1

### Citation

Mohamed Ghattassi. Modélisation, observation et commande d’une classe d’équations aux dérivées partielles : application aux matériaux semi-transparents. Mathématiques générales [math.GM]. Université de Lorraine, 2015. Français. ⟨NNT : 2015LORR0123⟩. ⟨tel-01751836⟩

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