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This paper presents two infrared thermography methods with CO 2 Laser excitation and microwave excitation applied to defect detection in CFRP. The tests were conducted with two specimens, one with defect, and another one without defect. On two concrete plates 40 cm × 40 cm × 4.5 cm were reinforced by CFRP; the defects were made by the absence of adhesive on an area 10 cm × 10 cm. The specimens were heated by microwave, generated by a commercial magnetron of 2.45 GHz and guided by a pyramidal horn antenna, with a power of 360 W within 150 s. Another series of the tests was conducted with CO 2 Laser, wavelength 10.6 µm, by heating the samples with a power of 300 W within 40 s. An infrared camera sensitive to medium waves in range of 3-5 μm, with a detector of 320 × 256 matrix detector in InSb (Indium Antimonide), was used to record the thermograms. As a result, the CO 2 Laser excitation is better for the delamination detection in CFRP. This study opens interesting perspectives for inspecting other types of defects in materials sciences; the microwave excitation is suitable for the deep defects in the materials whereas the CO 2 Laser excitation is better for the defects near the surface of the materials.

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The model-based control of building heating systems for energy saving encounters severe physical, mathematical and calibration difficulties in the numerous attempts that has been published until now. This topic is addressed here via a new model-free control setting, where the need of any mathematical description disappears. Several convincing computer simulations are presented. Comparisons with classic PI controllers and flatness-based predictive control are provided.

The determination of both the thermal and thermodynamical properties of a composite material containing phase change material is done thanks to an inverse method, which combines experimental measurements and numerical computations. Given first an in-house experiment, which allows us to test samples at a macroscopic scale (i.e., close to the real conditions) and to set various types of thermal stresses, and secondly the simulation of the corresponding thermal behavior, relying on an accurate thermodynamical modeling and taking into account the real operating parameters (e.g., thermal contact resistances and non-symmetric heat fluxes on each side), it is possible to characterize the solid and liquid thermal conductivities and heat capacities, as well as the temperature range associated with a non-isothermal phase transition and the associated latent heat. The specificity of the present approach is to allow, in a single step, a characterization of all the involved thermo-physical parameters that are usually required in simulation tools (e.g., EnergyPlus…). Moreover, the hitherto studies dealing with repeatability and uncertainties of the enthalpy characterization are generally very scant and not encountered very often or only with qualitative assessments. This is a clear caveat, especially when considering any system design. Therefore, for the first time ever, the present paper pays a special attention to the repeatability of the identification method and studies the scedasticity of the results, that is to say the deviations of the determined enthalpy curves, not only from a qualitative point of view but also by proposing quantitative arguments. Finally, the results are very promising since the agreement between all trials is excellent, the maximum error for all parameters being lower than 4%. This is far below the current quality thresholds admitted when characterizing the enthalpy of a phase change material.

The characterization of thermal systems can be performed by using thermal impedance measurements. Experimentally, this method requires simultaneous measurements of the variations in heat flux and the temperature of the measuring surface. The sensor, placed on the system to be characterized, induces a disturbance. For a slow change in thermal characteristics and for low frequencies, the disturbance due to the sensor is negligible. The low-frequency case has been studied in several works, but we show here that it is possible to extend the method to higher frequencies by taking the sensor disturbance into account. A model accounting for sensitivity to parameters shows that in a zone called 'the middle frequency zone' the disturbance is limited to a resistive effect. This zone is studied in this work and concrete was tested under these conditions. Several tests were carried out on the same sample. The contact resistance was modified for each test and the method used led to a stable value of material effusivity.

It is proposed to apply a method for identifying thermal effusivity in order to monitor the percolation of water in a soil by means of a noninteger order model. This model is expressed in the form of a linear relation connecting the fractional derivatives of the temperature at a point of the system to the fractional derivatives of the stress applied, namely a flux. These derivatives are replaced by their discrete definitions and the model coefficients are identified from experimental measurements by a method of linear least squares. Flux sensors are used to measure the flux and temperature simultaneously in the access plane to the system, enabling the thermal impedance to be calculated. The study is made up of two parts:The first part consists in establishing in the laboratory a correlation between the effusivity and water content of a sample of ground studied by traditional methods.The second part constitutes the in situ tests, where with the flux sensors and the application of the method, the effusivity of the ground can be estimated and thus the water content deduced.

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