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A simple physical model is presented to predict the neutron diffraction properties of deformed crystals. The main interest of this model is its general applicability to deformed crystals and its mathematical simplicity. At first this model was applied to curved crystals and its validity was checked by comparison with the diffraction patterns obtained from the exact solution of the dynamical neutron diffraction theory. A comparison between the prediction of the model and experimental data in curved Si crystals is presented. Finally the model is used to predict neutron diffraction patterns by crystals with a gradient in the lattice spacing and by deformed crystals in the general case.

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The aim of this research is the study of the laminar boundary layer separation phenomena on aerodynamic bodies by infrared thermography. The presence and the size of laminar bubble are mainly observed. A thermographic method is adjusted to detect the presence and the longitudinal dimension of the laminar bubble. In this region the convective heat transfer coefficient is lower than in the surroundings, because of the recirculating flow. Heating the airfoil surface, the laminar bubble will appear warmer than the other zones and so it is possible to know its presence and position.