Liste des communications
Nanostructured CuO directly grown on copper electrochemically: synthesis and characterization
Nanostructured CuO was directly grown on copper foam. The Cu foil was modified electrochemically by Cyclic voltammetry (CVs) a three electrode cell with Cu foam working electrode, platinum foil counter electrode and saturated calomel reference electrode in 5 M KOH solution,after reaction for Cu electrooxidation at room temperature. The shiny Cu foil surface turned to complete black after the reaction. The obtained electrode (denoted as CuO/Cu). The morphology and structure of the CuO were examined by X-ray diffraction spectroscopy. Voir les détails
Mots clés : Copper substrate, cyclic voltammetry
Répartition de champ électrique dans un système pointe-plan avec barrière isolante
The objective of our work is the study by numerical simulation of the distribution of the electric field according to geometric measurements of the insulating barrier and its position in the inter-electrodes gap Voir les détails
Mots clés : Electrical discharge, insulating barrier, finite element, electrical field
Monitoring and Fault detection of the Stator short circuit fault in induction motor based on the FuzzyLogic approach
the diagnostic of the induction machinesbecomes more and more important. This made necessarythe monitoring function condition of these machines forimproved an exploitation of the installation. The aim ofthis work is the proposal of a monitoring strategy based onthe fuzzy logic, that informs us about the healthy and faultoperating condition of short-circuit between turns of thestator windings. The principle adopted for the strategysuggested is based on monitoring of the average root meansquare (RMS) value of the stator current, which will beuseful as input data with the fuzzy logic block andconsidered to making decision on the machine state. Voir les détails
Mots clés : Induction Machine Monitoring, Detection, Fuzzy logic, RMS, modeling, Simulation.
Effects of a circular defect size and position on the damage progression in hybrid laminates under compressive loading
The effects of a circular defect size and position on the post-damage response of the FMLs laminates under compressive loading have been studied. Compression tests are performed on composite plates comprising a hole having different diameters (8 mm, 12 mm and 18 mm) and located at different positions (25%, 50% and 75%) in the loading direction. A numerical analysis using the finite element method FEM has permits the identification of the initiation zones and the description of the damage evolution in these laminates. The results of the numerical simulation are in good agreement with the experimental results. The FEM has well predicted the critical damage zones Voir les détails
Mots clés : FMLs laminates, damage progression, compressive loading, finite element
Early detection of short circuit between turns in stator winding of induction machines via multivariate statistics
Online monitoring of induction machine health is of increased interest, as the industrial processes that depend on the machines becomes more complex and as performance to cost ration of monitoring technology. Several efforts have been directed towards developing methods that use the conventional signal processing and pattern classification techniques. This paper focuses on fault diagnosis in induction machines operating under transient conditions. A new tool of anomaly detection based on multi-scale entropy MSE of Park vector approach and information theory combined with current trajectory mass center with principal component analysis (PCA) are proposed. The faults study in this paper is short circuit between turns in stator winding of induction machine. Simulation results show that the proposed method are able to detect short circuit between turns in stator winding of induction machine in the permanent period. Voir les détails
Mots clés : Induction machine, Fault Diagnosis, Multi-scale entropy, principal component analysis, Current trajectory mass center
Structural, elastic, electronic and chemical bonding properties of the semi-conductor matérials Ba2OsH6: An ab initio study
Several applications of hydrides have been found so far. During the last decade, applications such as hydrogen storage/economy [1,2], rechargeable batteries [2], etc., have been the subject of intensive research efforts. After the discovery of the switchable optical properties of yttrium and lanthanum hydride films [3], hydrides have found another application as smart windows [3–4]. For the above listed specific applications of hydrides fast kinetics of hydrogenation/dehydrogenation processes, low temperature at which the hydrogenation/dehydrogenation occurs, large hydrogen content, low total weight and powder form of hydrides are extremely important. However, hydrides with large total weight, low concentration of hydrogen atoms and high temperature for activation of hydrogenation/dehydrogenation processes have received little or no attention. Recently, this class of hydrides has been suggested as a source of important applications in semiconductor electronics, such as transparent conducting materials [5] and semiconductor p–n junctions [6]. Voir les détails
Mots clés : structural, elastic, electronic, chemical bonding ab initio calculations, Electronic band, densities of states, Charge density.
Caractérisation thermique et tribologique des composites thermostructuraux C-C et composite à matrice organique
Le comportement tribologique sec des couples acier-composite thermostructuraux carbone-carbone et acier-composite à matrice organique et les phénomènes dû aux frottements sont étudiés. En utilisant un modèle mathématique, la température superficielle du contact a été déterminée. Les résultats illustrent l’évolution de la température en fonction du temps. La charge normale, la vitesse de glissement et le coefficient de frottement ont une influence significative sur la variation de la température Voir les détails
Mots clés : température, frottement, acier, composite, disque, garniture
Optimization of Optical Gain in Inx Ga1-xSb/GaSb unstrained quantum well structures for detection
In this paper we study the effects of In concentration, temperature, quantum well width and carrier density on optical gain for GaSb/In1-xGaxSb/GaSb untrained quantum well structures. This system was chosen as it is useful in infrared emission, finally, we introduce the optimum structure of quantum well to obtain the maximum optical gain, at room temperature and infrared emission particularly 2.3 (µm), for the use this structure in application of spectroscopic analysis of the gases specially CH4. Voir les détails
Mots clés : Quantum well, In1-xGaxSb, optical gain, laser, Detection
Résolution de problème inverse en utilisant l’algorithme diagonale Détendu projections orthogonales (DROP) de reconstruction d'image à rayon x
Dans ce travail, nous présentons l’application des algorithmes basés sur les méthodes algébriques, de reconstruction d’image en tomographie à rayon X. Ainsi, les algorithmes de DROP avec régularisation quadratique (Projections orthogonales diagonale Relaxe), Gradient conjugué seront implémentés et appliqués à des images réels obtenues par un tomographe à Rayons X, Une étude comparative est faite dans le but d'examiner les résultats des algorithmes de reconstruction. Voir les détails
Mots clés : Méthode DROP, régularisation, Tomographie, Gradient Conjugué
Synthèse et caractérisation de nano-hydroxyapatite
Plusieurs procédés de synthèse chimique ont été développés pour préparer la poudre hydroxyapatite (HA) en utilisant divers types de sources de calcium (Ca) et de phosphate (PO4). Dans le présent travail, nous rapportons les conditions d’élaboration d’une poudre nanométrique de HA en utilisant la coquille d’œuf de poule comme source de Ca. La synthèse a été effectuée à partir de la réaction chimique de Ca(OH)2 obtenu après traitement thermique des coquilles et l’acide phosphorique H3PO4, en présence de L’EDTA comme agent chélateur et le NH4OH pour ajuster le pH. Les produits ont été caractérisés par diffraction des rayons X et microscopie électronique à balayage. Voir les détails
Mots clés : hydroxyapatite, nano-poudre, synthèse par voie humide, DRX, MEB