Intumescent coatings are designed to react when they are heated, by building up a swollen multi-layered insulating structure. The substrate onto which they are applied is then actively protected. In a military framework, it is crucial to provide efficient protection to a wide range of devices and vehicles, which must be able to sustain intense thermal conditions such as fires or explosions. For this purpose, the behaviour of intumescent paints under exposure to high thermal fluxes is investigated. In order to develop and validate a model describing heat transfers in materials protected by intumescent coatings, experimental simulations of different types of radiative aggressions were carried out. A 45 kW solar furnace was used as a heat source, which allowed simulating fires and explosions. Temperature ranges and kinetics calculated by the model are similar to those observed and measured during the experiments. The mathematical model, initially developed for fire simulations, also proves efficient in the case of thermal fluxes induced by brief, violent explosions. However, the results show that a better identification of each layer's thermal properties is needed to improve the accuracy of the model. For this purpose, an experimental identification campaign using the solar furnace has to be developed.
Temperature evolution and skin burn process resulting from a laser radiation exposure are investigated in this paper. Transient temperature in skin is numerically estimated using a 1-D multilayered model based on Penne's equation. The degree of burn injury is numerically evaluated by using an Arrhenius-type function. Unfortunately, most of the mathematical model parameters are not well defined in literature. Thus, a sensitivity analysis has been performed in order to evaluate the effect of each parameters inaccuracy on temperature estimation and on burn injuries prediction (according to several authors' characterization). Investigated parameters uncertainties that crucially invalidate the thermal model are as follows: epidermis and dermis volumetric heat, extinction coefficient, and skin thickness of the affected area. Considering the damage prediction, the activation energy is a key parameter for the validation of an efficient predictive tool.
This paper deals with the H∞ stabilization of the spatial distribution of the current profile of tokamak plasmas using a Linear Matrix Inequalities (LMIs) approach. The control design is based on the one dimensional resistive diffusion equation of the magnetic flux that governs the plasma current profile evolution. The feedback control law is derived in the infinite dimensional setting without spatial discretisation. The proposed distributed control is based on a proportional-integral state feedback taking into account both interior and boundary engineering actuators. Supporting numerical simulations are presented and tuning of the controller parameters attenuating uncertain disturbances is discussed.
This paper deals with the robust stabilization of the spatial distribution of the tokamak plasmas current profile using a sliding mode feedback control approach. The control design is based on the 1D resistive diffusion equation of the magnetic flux that governs the plasma current profile evolution. The feedback control law is derived in the infinite dimensional setting without spatial discretisation. Numerical simulations are provided and the tuning of the controller parameters that would reject uncertain perturbations is discussed. Manuscript received March 2, 2011. This work was supported in part by the CEA (Commissariatá l'Energie Atomique) and the French région Pays de Loire. O. Gaye is with LISA (EA 4094
This paper deals with the robust stabilization of the spatial distribution of tokamak plasmas current profile using a sliding mode feedback control approach. The control design is based on the 1D resistive diffusion equation of the magnetic flux that governs the plasma current profile evolution. The feedback control law is derived in the infinite dimensional setting without spatial discretisation. Numerical simulations are provided and the tuning of the controller parameters that would reject uncertain perturbations is discussed. Closed loop simulations performed on realistic test cases using a physics based tokamak integrated simulator confirm the relevance of the proposed control algorithm in view of practical implementation.
In this paper, an experimental technique dedicated to thermal diffusivity or thermal conductivity identification in isotropic and orthotropic materials is investigated. A method based on the analysis of thermal waves induced by periodic excitation in planar samples is proposed. Either frequency sweep at a single point in space or spatial fluctuations at a single frequency are considered. In such a context, in order to state both the accuracy and robustness of the data manipulation, a complete mathematical study is performed. Moreover, a sensitivity analysis allows us to implement an optimal strategy for the unknown parameter identification. Forward model and inverse problem are validated both on numerical simulation and known materials. Then, the presented experimental device developed is implemented for the analysis of orthotropic materials.
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