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Theses

Développement de méthodes d'identification des propriétés thermo-physiques de matériaux semi-transparents

Abstract : This thesis aims to develop the methods for characterizing the thermophysical properties of semi-transparent materials. First of all, an unsteady axisymmetric 2D conductive-radiative direct model aiming at modeling a "flash method" experiment in which excitation is localized in space and time is developed. The radiative heat transfer within the material characterized by the mean absorption coefficient is simplified by using the P1 method. The simplified radiative heat transfer equation, as well as the energy equation, are solved by the finite volume method. Afterwards, an identification model coupling the direct simulation, the experimental data and the particle swarm algorithm (PSO) is developed to simultaneously identify the thermal conductivity and the mean absorption coefficient of the semi-transparent material. In the next part, an identification model based on a multilayer artificial neural network is proposed and tested. The training and test phases of the neural network are performed using a database generated by the direct model. Synthetic data with different noise levels and experimental data are used to respectively demonstrate the robustness and feasibility of this approach to solve practical problems. Finally, in order to reduce the calculation time and increase the identification efficiency, a low-order reduced model of the direct model is built using the modal identification method and tested under different boundary conditions. The coupling of this reduced model with experimental data is not implemented, which are considered as one of the perspectives of this thesis.
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Yang Liu. Développement de méthodes d'identification des propriétés thermo-physiques de matériaux semi-transparents. Autre. ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers, 2019. Français. ⟨NNT : 2019ESMA0019⟩. ⟨tel-02860060⟩

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