Liste des communications
DETERMINATION DE L’ENDURANCE D’UNE SOUDURE HETEROGENE EN ACIERS INOXYDABLE DUPLEX / SUPERMARTENSITIQUE
L’objectif de cette étude est d’estimer l’endurance d’un joint de soudure hétérogène en acier inoxydable. Les résultats montrent que dans le domaine de fatigue à grand nombre de cycle (High Cycle Fatigue), la zone critique possède l’endurance la plus faible, avec une valeur de 265 Mpa relatif au métal fondue. Les endurances deux matériaux de base sont sensiblement proches situées a un niveau de 300 Mpa. Voir les détails
Mots clés : fatigue, Endurance, soudage hétérogène, acier inoxydable, duplex, Supermartensitique
EMPIRICAL MODE DECOMPOSITION BASED SUPPORT VECTOR MACHINES FOR MICROEMBOLI CLASSIFICATION
The classification of circulating microemboli, in the bloodstream, as gaseous or particulate matter is vital for selecting appropriate treatment for patients. Until now, Doppler techniques have shown some limitations to determine clearly the nature of circulating microemboli. The traditional techniques are largely based on the Fourier analysis. In this paper we present new emboli detection method based on Empirical mode decomposition and support vector machine using Radio Frequency (RF) signal instead of Doppler signals. Voir les détails
Mots clés : classification, Microemboli, Radio Frequency signals, Empirical Mode Decomposition, ultrasound.
Photovoltaic array modeling and MPPT using artificial neural network.
The good operation of a photovoltaic system depends on weather conditions such as illumination and temperature, because for example in a mobile station powered by a photovoltaic source, power supplied by the photovoltaic generator fluctuates when changing direction or during passage in poorly sunny, In other words, a good photovoltaic system is where the power delivered by the photovoltaic generator is maximum whatever the conditions. In the present work, we will precede first time modeling of solar cells by neural networks, then, we will use this approach to track the point of maximum power regardless of the location of use and operating conditions.; ; ; ; . Voir les détails
Mots clés : signal diode model, modeling, photovoltaic array, Neural Network, MPPT
Modélisation et Commande Vectorielle d’une Machine Asynchrone à Sept phase
In this work, we present the modeling and vector control of seven-phase induction machine, regularly shifted them in space. The modeling is based on the method of diagonalization of matrices inductors to magnetically decouple phases. Secondly, the vector control used is intended to obtain the excellent performance of the DC machine Voir les détails
Mots clés : Seven-phase Asynchronous machine, diagonalization, vector control
Propagation characteristics of Chirped Vector Soliton in optical fibers with variable coefficients
In this work we study the propagation characteristics of chirped vector solitons in optical fiber systems with variable coefficients by using the compact split step Padé scheme (CSSPS). The numerical simulations show that the chirped managed vector soliton with different perturbations maintains its characteristics during propagation along the polarization maintaining optical fiber. Voir les détails
Mots clés : vector soliton, chirped soliton, optical fibers, compact split step Padé scheme, coupled higher-order nonlinear Schrodinger equations, temporal waveform.
L’influence de la pression des gazes dans un plasma de la pulvérisant cathodique DC sur les propriétés des couches minces de ZnO.
Des couches minces de ZnO ont été déposées par pulvérisation (DC) d'une cible métallique de Zinc, en utilisant un plasma d’un mélange de gaz (argon, oxygène) avec des pressions variantes de l’Oxygène et à une température de 100 °C. Ces couches sont caractérisées par la transmission optique UV visible et les mesures de conductivité électrique. Les mesures de transmission optique des couches montrent que la transmission optique est très élevée (facteur de transmission) dans la gamme de longueurs d’ondes située entre 400 nm et 2500 nm et elle variée en fonction de la pression d’oxygène. Les mesures électriques I-V et I-T mettent en évidence l’effet de la pression d’oxygène dans le plasma sur la conductivité et l’énergie d’activation des couches élaborées. Voir les détails
Mots clés : pulvérisation réactive, oxyde de zinc, propriétés optiques, caractérisation structurale, conductivité électrique.
Identification parameters with neural network for Preisach hysteresis model
The description of hysteresis is one of the classical problems in magnetic materials. The progress in its solution determines the reliability of modeling and the quality of design of a wide range of devices, the proposed approach has been applied to model the behavior of many samples and the results show the robustness and efficiency of Neural Network to model the phenomenon of hysteresis loop. The goal of this study is to optimize the parameters of hysteresis Loop by Preisach model with the Neural Network, the method developed is based on an analysis of two distribution functions. The modified Lorentzian function and Gaussian function have been analyzed. The implemented software and performances of the distributions are presented. Voir les détails
Mots clés : Gaussian Distribution, Hysteresis Loop, Lorentzian Distribution, Neural Network, Preisach Model
Identification of Jiles-Atherton model parameters using genetic algorithms
The purpose of this paper is to propose a robust and fast method to estimate the parameters of Jiles-Atherton model of ferromagnetic hysteresis by using genetic algorithms for reconstruction of hysteresis loops. The performance of the method is evaluated by experimental data. Jiles-Atherton model with five parameters describes the hysteresis behavior of ferromagnetic materials. To calculate the model parameters, many researchers use analytical and classical iterative methods, the most often those methods does not converge or give unphysical results. Because the characteristic equations are sensitive to the initial values of iteration and has non-unique solutions, which is caused by nonlinearity of the characteristic equations and the fact that there are more unknown quantities. The optimization by genetic algorithms method allows to avoid local minima and find global roots is then applied to obtain the model parameters. The proposed method overcomes the difficulties of the other techniques which assume zero remanence. It is also robust as it is guaranteed to converge to physical solutions. Voir les détails
Mots clés : Jiles-Atherton model, hysteresis loops, Identification of parameters, genetic algorithms (GA)
Determination of distribution functions and optimization of parameters for the Preisach hysteresis model by Practical Swarm Optimization (PSO)
In this work we present the Preisach model for the simulation of the magnetic hysteresis. This model is able to represent the hysteresis property of versus materials if it’s distribution function µ(α,β) and his parameters are well determined. Four distributions functions, the modified Lorentzian, Guassian, Gauss-Gauss and lognormal- Gauss are used and optimized to simulate the hysteresis loops. In the last step, the optimal distribution function and there parameters of the Preisach model are determinate via practical swarm optimization (PSO) and results are compared with experimental ones. Voir les détails
Mots clés : Preisach Model, Distribution Function, practical swarm optimization (PSO)
Influence of the position and number of circular notches on the buckling of metal pipes
Thin cylindrical shells are very sensitive to buckling when loaded mechanically and / or thermally. This complex phenomenon has become a major concern. In the present work, the aim is to predict the buckling behavior of imperfect metal pipelines, subjected to compression resulted in an imposed displacement. Following the results obtained by numerical simulation through the Abaqus code, we find that more the distance between the circular notches is greater, more the resistance to buckling is important, but from a distance of 30mm, the position of the notches whatsoever longitudinal or radial has no significant effect. While in approaching both ends of the pipe, the buckling becomes less important. Voir les détails
Mots clés : Pipe, Buckling, circular notches, finite element analysis.