Liste des documents
Modelling, Faults Detection and Diagnosis of Squirrel-Cage Self Excited Induction Generator for Isolated Wind Energy Conversion System
The condition monitoring of the Squirrel-cage Self-Excited Induction Generator (SEIG). can significantly reduce the costs of maintenance, prevent the unscheduled downtimes and make the best maintenance decisions for isolated Wind Energy Conversion Systems (WECS). On the other hand, growing attention has been paid to fractional calculus theory in practical control field for many industrial applications. In this paper, an on-line diagnostic procedure for stator and rotor faults in the squirrel SEIG of isolated wind energy conversion system is presented. This diagnostic procedure is based on stator current analysis by FFT. A generalized model of the squirrel-cage SEIG is developed to simulate both the rotor and stator faults taking iron loss, cross flux saturation into account. Additionally, a new control strategy is proposed for the fixed operation of the wind turbine, based on fractional PIλ controllers. Voir les détails
Mots clés : Issam Attoui, Amar Omeiri
FAULT DETECTION AND DIAGNOSIS IN ROTATING MACHINERY BY VIBRATION MONITORING USING FFT AND WAVELET TECHNIQUES
Rotor unbalance is the most cause of machine vibration that reduces the life of the rotating machine. On the other hand, vibration monitoring is reported as an interesting technique for the rotating machinery condition diagnosis.This paper considers the Wavelet Transform (WT) and FFT of vibration signals for detect and diagnose of unbalance faults in rotating machinery. The fault condition and location of faults are success fully detected by WT-FFT for non-stationary vibration measurements obtained from accelerometer sensors. Experimental studies on the rotating machine include faulty rotor with different rotational speeds has been carried out in this paper. These experimental results confirm that WT-FFT serves as a good tool to online faults detection and diagnosis of rotating machines. Voir les détails
Mots clés : Rotor unbalance, fault detection and diagnosis, Rotating machinery, WAVELET TECHNIQUES
Modélisation d’une chaine de conversion d’énergie éolienne Basée sur une machine asynchrone à double alimentation.
Actuellement, les éoliennes utilisant une génératrice asynchrone à double alimentation « GADA » sont les plus utilisées pour production de l’énergie électrique. Notre travail consiste dans la première étape à la modélisation de la chaine de conversion de l’énergie éolienne où la génératrice asynchrone à double alimentation fonctionne à vitesse variable. Et, en seconde étape, on considère le réglage des puissances active et réactive afin d’assurer un fonctionnement optimal. A cet effet, une commande vectorielle est appliquée pour assurer un découplage entre ses grandeurs électromécaniques. Ces deux parties, sont développées et programmées sous Matlab/Simulink a fin d’analyser par simulation le comportement de la chaine dans les différant domaines de fonctionnement possibles. Les résultats de simulations obtenus seront présentés et analyser. Voir les détails
Mots clés : Aérogénérateur, Turbine éolienne, GADA, MLI à bande d’hystérésis.
Fast Waveguide Filter Synthesis, using the Mode Matching Method for Analysis and Practical Swarm Optimization
In this paper, we give two examples of rectangular waveguide bandpass filter synthesis. Starting from the filter specifications (order of the filter, position of zeros, band-edge frequencies, and passband return loss) our aim was to realize one program that makes all steps of the filter synthesis (calculate the coupling matrix, create the equivalent circuit, convert the equivalent circuit to waveguide structure, analyze this structure, and then optimize its dimensions), and doing this as fast as possible (less than two minutes). For the coupling matrix we used the Atia and Williams’s method, for the analysis we used the mode matching method, which is the most adequate for this kind of structures, and for the optimization we used the Practical Swarm Optimization PSO. The complete combination has been successfully applied for several waveguide filters synthesis. Voir les détails
Mots clés : waveguide bandpass filter, Practical Swarm Optimization, mode matching
Task Performance Evaluation for Industrial Robots
Integrated multi-modal Supervisory Control Systems(ISCS) are a new generation of complex and synergistic Human-Machine Interaction Systems (HMIS). This paper deals withmulti-modal interaction and control applied to HRS. A taskperformance evaluation technique dedicated for multi-modalinteraction and control is proposed. It enables comparison oftask performance carried out by using different selection ofcontrol modes or by different operators. Objective andsubjective performance measures are defined. Based on theanalytical hierarchy process method (AHP) which takes intoaccount qualitative and quantitative attributes and criteria.Experimental results have been carried out and somepreliminary results will be presented concerning industrialmanipulators. Voir les détails
Mots clés : Task performance evaluation, Robotics, human factors, Analytical Hierarchy Process, Adaptive supervisory control, Multi-modal interaction, Graphical-user interface.
Solution of the State-Space Linear Fractional Order Systems
A useful representation of fractional order systems is the state space representation. For the linear fractional systems of commensurate order, the state space representation is defined as for regular integer state space representation with the state vector differentiated to a real order. This paper presents a solution to the state space linear fractional systems of commensurate order. The solution is obtained using a technique based on functions of square matrices and the Cayley-Hamilton Theorem. The solution is calculated in the form of a linear combination of suitable fundamental functions. The basic ideas and the derived formulations of the technique are presented. An example is also given to demonstrate the effectiveness of the presented analytical approach. Voir les détails
Mots clés : Cayley-Hamilton theorem, fractional order differential equations, fractional state space, Functions of matrices, rational function
Mise en forme des composites à matrices céramiques
Les composites à matrice céramique (CMC) sont des matériaux qui connaissent un bel essor ces dernières années, ils deviennent une alternative des composites à matrice organique (CMO). Dans cette contribution, nous présentons les principales voies d'obtention de ces composites.Etant donné que les composites à matrice céramique, contrairement aux CMO, ne sont pas mis en forme par moulage, mais plutôt par dépôt dont les procédés employés comportent deux étapes ; premièrement la fabrication d’une préforme suivie par une densification de cette dernière.Pour le dépôt de la matrice céramique au niveau du tissu, des précurseurs sont infiltrés sous formes liquides ou gazeuses. La voie liquide est relativement rapide mais donne des matrices poreuses de qualité moyenne, tandis que la voie gazeuse présente un bon contrôle de la composition des matrices (pureté, fonctions techniques...) mais extrêmement lente et coûteuse, ce qui la rend adaptable aux applications les plus spécifiques. Voir les détails
Mots clés : composite, Mise en forme, céramique
ETUDE LE COMPORTEMENT MECANIQUE D’UN MATERIAU COMPOSITES PAR LA METHODE DES ELEMENTS FINIS
Les matériaux composites sont par essence des matériaux offrant de grands potentiels pour la conception de pièces de haute performance mécanique présentant, en général, des formes relativement complexes. Par ailleurs, les nombreuses géométries et configurations des renforts permettent une grande variété de propriétés et un bon contrôle de leur anisotropie. Dans ce travail on a utilisé la méthode des éléments finis, pour étudier le comportement mécanique d’un matériau composite en flexion 3 points. Le but de notre étude est de mettre en évidence l’influence d’orientation des fibres sur le comportement du matériau, ainsi que la distribution des champs des contraintes et des champs des déformations dans chaque pli. Voir les détails
Mots clés : composite, flexion comportement m´ecanique ´el´ement fini, simulation
Study the influence of temperature on the mechanical behavior of low density polyethylene (LDPE) by genetic algorithms (GA)
Mathematical models are more and more used to simulate law mechanical of materials.In this work, genetic algorithm (GA) [1] was performed to determine the law of tensile mechanical behavior of low density polyethylene (LDPE), for a uniaxial tensile test .The parameters taken into account are the constraints based deformation for temperatures as 25 ° C and a strain rate included between 5.10-3s-1 and 50.10-3s-1 . . Our simulation results are compared with experimental work.To do this, and to approach the law of the mechanical behavior of the material used in our work, we opted for the method of genetic algorithm , or GA, as a method of simulation, we have applied to LDPE. Voir les détails
Mots clés : polymer, LDPE, mechanical response, Genetic algorithm, effect of temperature
Microstructural and magnetic characterization of Cu-Ni nanocrystalline powders.
Cu50Ni50 nanocrystalline powders have been prepared by mechanical alloying from pure elemental Ni and Cu powders in a planetary ball mill, at room temperature, under argon atmosphere. Morphological, structural, microstructural and magnetic properties of the ball milled powders were characterized by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. The total mixing of the elemental powders gives rise to the formation of Ni(Cu) and Cu(Ni) solid solutions. Both the saturation magnetization and the coercivity decrease from 53emu/g and 39.4Oe, respectively, for pure Ni to about 12.65emu/g and 19.5Oe after 30 h of milling. Voir les détails
Mots clés : Cu50Ni50 nanocrystalline powders, Mechanical Alloying, Microstructural and magnetic properties.