Bertrand Nogarede

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This paper deals with a deterministic and rational way to design piezoelectric transformers in radial mode. The proposed approach is based on the study of the inverse problem of design and on its reformulation as a mixed constrained global optimization problem. The methodology relies on the association of the analytical models for describing the(More)
The optimal design of electrical machines can be mathematically modeled as a (mixed-integer) nonlinear optimization problem. We investigate the impact of different mathematical formulations on the results obtained using a local optimization solver which is well-known in the engineering community: MatLab’s fmincon function. Our analysis is based on six(More)
This paper focuses on the analysis, the modeling and the control of a linear-switched reluctance motor. The application under consideration is medical, and the actuator is to be used as a left ventricular assist device. The actuator has a cylindrical or tubular shape, with a mechanical unidirectional valve placed inside the mover, which provides a pulsatile(More)
Today, power electronic reliability is a main subject of interest for many companies and laboratories. The main process leading to the IGBT failure is the cycling thermal stress. Indeed the current flow induce local heating and then mechanical stress. This paper deals with electro thermal stress under steady and transient current states. The main objective(More)
In this paper, we discuss, through a simple example, the impact of two different but equivalent formulations used by standard local optimization solvers (here fmincon of MatLab). We show that even if the two formulations are equivalent in a mathematical sense (no loss of global optima) it is not completely true in a numerical way; using 1000 starting(More)
This study is focused on the IGBT wire bond behaviour. We apply a direct current flow within the wire to reproduce the thermal cycling test used in reliability studies. On one hand we compare the temperature distribution between 3D FEM simulation and the experimental temperature measurement. We also point out the Von-Mises stress obtained. On the other hand(More)
BACKGROUND AND AIM OF THE STUDY Valve repair is currently performed to treat mitral regurgitation, but aortic valve repair remains a surgical challenge. In contrast, aortic valve replacement leads to complications and constraints on the patients' quality of life and valve durability. The mechanisms that produce malcoaptation of the aortic leaflets, with(More)
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