Liste des publications
A numerical investigation of both thermal and texturing surface effects on the journal bearings static characteristics
Journal bearing characteristics modellization has been investigated in this paper for both cases of texture presence or absence onto the bearing surface. The thermal effect has been studied. The used numerical approach in this analysis is finite difference method. The textured bearing performance enhancement passes essentially by a minimum film thickness and a friction torque improvement through an appropriate surface texture geometry and right texture distribution on the bearing surface. It is found that the simulations results are in good concordance with those issued from the literature. The obtained results by considering the temperature effect are more realistic. Voir les détails
Mots clés : Journal bearings, Reynolds equation, Hydrodynamic lubrication, Stribeck curve, texture
An advanced control approach for current harmonic cancellation using shunt active power filter
Generally, low harmonic frequencies such as the harmonic of the order 5 and 7 have agreat influence to deteriorate the network current and interim the grid power factor. The objectiveis; to cancel out the selected harmonic order from the network current. The shapes of waves andthe values of the THD of the network current before and after applying the proposed techniqueare introduced. The system is simulated and investigated using MATLAB/Simulink. The resultsprove the effectiveness of the design and control strategy (α-β). This paper deals with design,analysis and simulation of a three phase three wire shunt selective active power filter. Itcompensates the harmonic currents selectively under balanced power network. In order toimprove, the power factor of the supply network, an advanced control approach based on amultivariable filter is adopted. The novelty of the proposed control approach developed in thispaper is to use a multi-variable filter (MVF), which can extract the harmonics content of loadcurrent reference, according to the axis of Concordia. Voir les détails
Mots clés : harmonic, shunt selective active power filter control, power factor, multi-variable filter, MVF, axis of Concordia, THD
Condition Monitoring and Fault Detection in Wind Turbine Based on DFIG by the Fuzzy Logic
oubly-fed induction generator is widely used in wind turbine conversion systems. Several research works are being made to efficiently approve existing condition monitoring and fault detection techniques for these systems. The condition monitoring ofthese systems becomes more and more important, the main obstacle in this task is the lack of an accurate analytical model to describe a faulty DFIG in the majority of the research tasks. In this paper, we present the monitoring strategy of short-circuit fault between turns of the stator windings and open stator phases in doubly-fed induction generator by fuzzy logic technique. The stator condition monitoring is diagnosed based on the root mean square values of current magnitude in addition to the knowledgeexpressed in rules and membership function. The proposed strategy is verified using simulations performed via the model of Doubly-fed induction generator built in MatLab ® SIMULINK. Voir les détails
Mots clés : Wind turbine, DIFG, Monitoring, Detection fault, Fuzzy logic.
Influence des paramètres de traitement par brunissage sur la texture de la surface
Résumé : Le procédé de brunissage (galetage à la bille) est l’un des moyens de finition et d’amélioration de la texture de surface d’une pièce mécanique. La texture de la surface est matérialisée par la rugosité et l’orientation de la direction prédominante des stries en travers de la surface. Cette orientation est d’une grande importance dans un contact mécanique, elle peut être évaluée par le rapport d’aspect de texture " Str" appelé indicateur d’isotropie de la surface. Ce travail a pour objectif de mettre en relief, l’influence des paramètres de traitement par brunissage sur l’orientation des stries. Les paramètres considérés sont : l'effort appliqué " Py ", l'avance " f " et le diamètre de bille " Db ". Au moyen d’un modèle mathématique basé sur les plans factoriels de Box-behenken, un régime optimal offrant le meilleur rapport de texture " Str ", a été déterminé. Voir les détails
Mots clés : Modèle mathématique., paramètres de brunissage, paramètre de texture
Inferential Sensor - Based Adaptive Principal Components Analysis of Mould BathLevel for Breakout Defect Detection and Evaluation in Continuous Casting
This paper is concerned with a method for breakout defect detection and evaluation in a continuouscasting process. This method uses Adaptive Principal Component Analysis (APCA) as a predictor of inputs -outputs model, which are defined by the mould bath level and casting speed. The main difficulties that causebreakout in continuous casting are, generally, phenomenon related to the non-linear and unsteady state of themetal solidification process. PCA is a modeling method based on linear projection of the principal components;the adaptive version developed in this work uses the sliding window technique for the estimation of the modelparameters. This recursive form updates the new model parameters; it gives a reliable and accurate prediction.Simulation results compare PCA, APCA, nonlinear system identification using neural network (NN) and supportvector regression (SVR) methods showing that the APCA gives the best Mean Squared Error (MSE). Based onthe MSE, the proposed approach is analyzed, tested and improved to give an accurate breakout detection andevaluation system. Voir les détails
Mots clés : Soft sensor, continuous casting, Adaptive principal component analysis, breakout detection and evaluation.
Uncertainty estimation of mechanical testing properties using sensitivity analysis and stochastic modelling
This paper is concerned with a method for uncertainty evaluation of mechanical propertiesin metal testing. This method uses a combined approach based on Monte Carlo simulationand Markov Chain (MCMC) as a computing procedure of different uncertainties of mechanicaland metallurgical parameters such as stress, and elongation. The MCMC is a stochasticmethod that computes the statistical properties of the considered states such as the probabilitydistribution function (PDF) according to the initial state and the target distributionusing Metropolis-Hasting (MH) algorithm. Conventional approach is based on the Guide ofUncertainty Measurement (GUM), the uncertainty budget is established for the stress andelongation parameters respectively. A comparative study between the conventional procedureand the proposed method is given. This kind of approaches is applied for constructingan accurate computing procedure of uncertainty measurement of mechanical and metallurgicalparameters. Voir les détails
Mots clés : Markov Chain Monte Carlo (MCMC) Metropolis-Hasting (MH) algorithm Mechanical and metallurgical testing Stress, elongation and hardness measurement Guide of Uncertainty Measurement (GUM)
CDR Antenna with Dual-Band 1.9/2.7 GHz for MIMO-LTE Terminals
In this letter, we present a compact dual-band dielectric resonator antenna for multi-input multi-output antenna is designed and fabricated. The proposed antenna consists of a single cylindrical dielectric resonator antenna (CDRA) excited from two orthogonal ports. The electromagnetic analysis is performed using the CST microwave studio software. To validate the proposed concept, experimental measurements are also performed. The measured results show that the CDRA provides two bands around 1.9 and 2.7 GHz, suitable for LTE applications. Moreover, the proposed design allows a very good isolation between the two ports and a low envelop correlation coefficient. Voir les détails
Mots clés : Dielectric resonator antenna, multi-input multioutput systems, LTE bands, isolation, envelop correlation coefficient
Integrated Flexible UWB/NB Antenna Conformed on a Cylindrical Surface
In this paper, an ultra-wideband (UWB) conformal monopole antenna integrated with a narrow-band (NB) rectangular slot antenna is designed and fabricated. The proposed structure consists of a circular disc monopole antenna printed on a cylindrical surface and fed by a coplanar waveguide line (CPW). A rectangular slot antenna, excited by a microstrip line, is integrated in the front of the UWB antenna. The simulations are performed using the CST Microwave Studio software. To validate the proposed antenna concept, an experimental prototype is fabricated and measured. The measured results show that the monopole antenna covers an ultra wideband from 2 GHz to 12GHz with S11 < −10 dB and provides a very good isolation with a transmission coefficient below −20 dB across the operating band. Compared to planar integrated antennas, the proposed conformed structure possesses an important wideband, which can be used in many wearable electronic applications and communication systems. Voir les détails
Mots clés : UWB, Conformal antenna
Enhanced Isolation MIMO Antenna with DGS Structures for Long Term Evolution Systems
In this communication, a new multi-antenna system based on two microstrip antennas is analyzed and proposed for LTE (Long Term Evolution) terminals. The multi-input multi-output (MIMO) antenna is printed on a FR4 substrate with size of 60×100×1.6 mm3. The proposed design, in its basic form, operates around 2.3 GHz, and provides a transmission coefficient of -19 dB. In order to improve the isolation between the two antenna ports, some rectangular and circular slots are inserted in the ground plane between the two antennas. With this modification, the mutual coupling of -59 dB was achieved, which are 40 dB improvements over the initial antenna. The simulated results are presented and discussed in term of reflection coefficients, transmission coefficients and radiation patterns. Voir les détails
Mots clés : MIMO antenna, mutual coupling, LTE (Long Term Evolution) terminals
High Isolation Microstrip MIMO Antennas for WLAN Systems
This paper introduces a novel design of aperture coupled microstrip antenna for MIMO array applications. The proposed antenna uses 2x4 patches excited from two ports via rectangular slots. HFSS (High Frequency Structure Simulator) and CST (Computer Simulation Technology)softwares are used to simulate the antennas performance. The results are given in term of S-parameters, radiation patterns and gain. In addition a parametric study is done to evaluate the effect of certain antenna parameters on the antenna performances. Form the simulated result, it is concluded that the proposed concept provides a good isolation between the two antenna ports (with low mutual coupling, S12/21). Voir les détails
Mots clés : High Isolation, MIMO antenna