Grenoble Institute of Technology

About: Grenoble Institute of Technology is a education organization based out in Grenoble, France. It is known for research contribution in the topics: Hyperspectral imaging & Geology. The organization has 3427 authors who have published 5345 publications receiving 137158 citations. The organization is also known as: Grenoble INP.

Predicting dislocation climb and creep from explicit atomistic details.

Abstract: Here we report kinetic Monte Carlo simulations of dislocation climb in heavily deformed, body-centered cubic iron comprising a supersaturation of vacancies. This approach explicitly incorporates the effect of nonlinear vacancy-dislocation interaction on vacancy migration barriers as determined from atomistic calculations, and enables observations of diffusivity and climb over time scales and temperatures relevant to power-law creep. By capturing the underlying microscopic physics, the calculated stress exponents for steady-state creep rates agree quantitatively with the experimentally measured range, and qualitatively with the stress dependence of creep activation energies.

Densification and microstructure evolution of Y-Tetragonal Zirconia Polycrystal powder during direct and hybrid microwave sintering in a single-mode cavity

Abstract: The densification and microstructure changes of 2 mol% yttria-stabilized zirconia nanopowder have been investigated during direct and hybrid microwave sintering. Microwave heating tests were achieved in a resonant single-mode cavity at 2.45 GHz and a cylindrical SiC susceptor was used for hybrid sintering experiments. Constant heating rate runs (25 °C/min) were controlled by adjusting the position of a sliding piston at constant forward microwave power. The temperature on the upper surface of the specimen was measured with an infrared camera. The final densities and the microstructures observed by SEM were compared to those of conventionally sintered materials. Homogeneous microstructures have been obtained by hybrid heating whereas direct microwave heating led to rather heterogeneous microstructures due to thermal gradients. Nevertheless, microwave-sintered materials always exhibited higher final densities for a given sintering temperature. This significant enhancement of the densification process was particularly observed in the intermediate sintering stage (1200–1350 °C range). Besides, grain growth was found to be mainly influenced by the sintering temperature rather than by the heating mode.

Fuzzy and Neural Control of an Induction Motor

Abstract: This paper presents some design approaches to hybrid control systems combining conventional control techniques with fuzzy logic and neural networks. Such a mixed implementation leads to a more effective control design with improved system performance and robustness. While conventional control allows different design objectives such as steady state and transient characteristics of the closed loop system to be specified, fuzzy logic and neural networks are integrated to overcome the problems with uncertainties in the plant parameters and structure encountered in the classical model-based design. Induction motors are characterised by complex, highly non-linear and time-varying dynamics and inaccessibility of some states and outputs for measurements, and hence can be considered as a challenging engineering problem. The advent of vector control techniques has partially solved induction motor control problems, because they are sensitive to drive parameter variations and performance may deteriorate if conventional controllers are used. Fuzzy logic and neural network-based controllers are considered as potential candidates for such an application. Three control approaches are developed and applied to adjust the speed of the drive system. The first control design combines the variable structure theory with the fuzzy logic concept. In the second approach neural networks are used in an internal model control structure. Finally, a fuzzy state feedback controller is developed based on the pole placement technique. A simulation study of these methods is presented. The effectiveness of these controllers is demonstrated for different operating conditions of the drive system.