Génie électrique

Nombre total de résultats : 78
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Les techniques de reconnaissance de Formes Application : à la reconnaissance de l’écriture Arabe

Rachid Zaghdoudi (2018)
Thèse de doctorat

Le domaine de la reconnaissance de l’écriture arabe manuscrite a reçu un intérêt de recherche intensif aux cours des deux dernières décennies et se concrétise aujourd’hui par un grand nombre d’applications opérationnelles. Malgré ces avancées, le problème reste ouvert à la recherche et à l’expérimentation à cause des caractéristiques morphologiques complexes du manuscrit arabe qui sont à l’origine de la défaillance des traitements. Les travaux de recherches présentés dans cette thèse s’inscrivent dans ce cadre et constituent une contribution au domaine de la reconnaissance de l’écriture arabe manuscrite. Dans un premier temps, nous proposons une approche globale basée sur une combinaison parallèle de classifieurs pour la reconnaissance hors ligne de mots arabe manuscrits. Le système développé s’articule autour de quatre modules distincts : prétraitement, extraction de primitives, classification basée sur deux types de classifieurs : SVM et k plus proches voisins flou et un module de combinaison. Des expériences ont été effectuées sur des images de la base de référence INF/ENIT ont montré l’efficacité du système proposé.En second temps, nous présentons un nouvel algorithme de segmentation en caractères des mots arabes manuscrits. Cet algorithme est fruit d’une coopération entre un ensemble de règles morphologiques spécifiques à l’écriture arabe (AMS) et un classifieur SVM mono classe, dont la tache principale consiste à accepter ou rejeter les points de segmentation primaires générées par le module AMS. Il a montré de bons résultats de segmentation sur des mots extraits de la base de données de référence IFN/ENIT. Voir les détails

Mots clés : reconnaissance de l’écriture arabe manuscrite ; combinaison de classifieurs ; séparateurs à vaste marge ; k plus proches voisins flou ; la transformée en cosinus discrète, histogrammes des gradients orientés ; segmentation.

Contribution to Reconfigured Multi-Level Inverter FedDouble Stator Induction Machine DTC-SVM Control

O. F. Benaouda, A. Bendiabdellah, B. Cherif  (2016)
Publication

The Dual Stator Induction Machine (DSIM) meets well with the need for high power applications. In the recent years, it has been increasingly used for variable speed drives. However, its control strategy is still a subject of research due to its complex structure, though it offers more reliable application in use due to the presence of double stators. The fault detection and localization in an inverter are profitable for better diagnosis and the inverter reconfiguration is the most required process to ensure acceptable service continuity. This paper tackles, on the one hand, a control strategy based on the Direct Torque Control combined with the Space Vector PWM of a DSIM (DTC-SVM-DSIM) and on the other hand, a three-level inverter fault detection and localization, reconfiguration of the inverter when operating under open-circuit IGBT switch faults. Several results are presented to illustrate the enhancement of torque and flux quality owed to the proposed control strategy and also to show the improvement of the open-circuit fault detection and localization method for better diagnosis as well as the inverter reconfiguration impact on the drive system service continuity. Voir les détails

Mots clés : DSIM, Multi-level Inverter, NPC, DTC, SVM, Reconfiguration

Bearing Fault Diagnosis Using De-noising Techniques Based on EMD Combined with Coefficients Correlation

Omar Fethi BENAOUDA, Rabah ABDELKADER, Abdelhafid KADDOUR, Ziane DEROUICHE  (2018)
Article de conférence

The vibration signals of a rolling bearing contain important information which can be used in early defect detection and diagnosis. This signal is usually noisy and the information about the fault can be lost. In this paper, a new denoising method based on Empirical Mode Decomposition Iterative Interval Thresholding and estimation of the correlation coefficient (EMD-corIIT) is presented. The results are compared with others proposed methods. The application of this technique to the experimental results shows that this method can extract effectively the fault features of rolling bearing compared with the others cited methods. Voir les détails

Mots clés : Denoising EMD, thresholding, vibration signal, Bearing Fault, Correlation Coefficients

Desired Closed-Loop Based Self-Tuning Fractional PID Controller for Wind Turbine Speed Control

N. Fergani, A. Charef, I. Attoui  (2015)
Article de conférence

Lately, fractional PID controller has gained more interests because it involves two more tuning parameters, the fractional order integration and the fractional order differentiation, in their structure. This type of controller has been introduced in the control system theory in a continuous effort to enhance the system control quality performances. In this paper a self-tuning fractional PID controller for wind turbine speed control is proposed. The fractional PID controller’s five parameters are self-tuned as the system dynamics or operating points change using formulas based on adesired closed loop response. A simulation study of the wind turbine speed control has been done to demonstrate and validate the performance and effectiveness of the proposed control scheme. Voir les détails

Mots clés : Fractional PID controller, self-tuning, wind turbine speed control

Analysis and evaluation of the impact of climatic conditions on thephotovoltaic modules performance in the desert environment

A Bouraiou, M. Hamouda, A. Chaker, M. Mostefaoui, S. Lachtar, M. Sadok, N. BOUTASSETA, M. Othmani, I. Attoui  (2015)
Publication

The main objective of this study is to investigate the impact of climatic conditions on the performance ofphotovoltaic modules installed in the desert region in south of Algeria. Firstly, the performance ofISOFOTON 100 module under daily weather conditions is evaluated. Next, the effects of partial shadingand accumulation of sand dust for a period of two months on power loss and the current–voltagecharacteristics of photovoltaic modules are examined. Finally, the visual inspection of the degradationof the UDTS 50 modules such as discoloration of encapsulant and delamination show the influence ofhigh temperature and the other climatic factors in the Saharan environment after a long time exposureof more than 10 years observed in the field at the Unit of Research in Renewable energy URERMS Adrar.The performance degradation is also assessed using (I–V and P–V) curves normalized at STC conditioncompared with the nominal STC data given by the manufacturer. The experimental results show thatthe performance parameters such as maximum output current (Imax), maximum output voltage (Vmax),maximum power output (Pmax), open-circuit voltage (Voc), short-circuit current (Isc) and fill factor (FF)of UDTS 50 modules are degraded after these years of exposition. Voir les détails

Mots clés : Photovoltaic module, Performance evaluation, degradation, Desert environment

Electromagnetic Interference Caused by High Voltage Power Lines on Buried Oil Pipelines

M.Ouadah, M.Zergoug, A.Younes  (2012)
Article de conférence

The electromagnetic interference caused by power transmission lines to oil and gas buried pipelines is under investigation for many years. Especially during fault conditions, large currents and voltages are induced on the pipelines that may pose danger to working personnel or may accelerate the corrosion of the pipeline’s metal. In this research, the induced voltage in the oil buried pipelines due to the magnetic fields produced by nearby 400kV transmission lines have been computed. This effect results in a corrosion process which we have proposed some solutions. Voir les détails

Mots clés : C Interference, Induced Voltages, Electric Power Transmission Lines, pipeline, corrosion, cathodic protection.

Analysis of the Electromagnetic Interferences betweenOverhead Power Lines and Buried Pipelines

M'hamed OUADAH, Mourad ZERGOUG  (2014)
Publication

The Analysis of electromagnetic interference between high voltage overhead power transmission lines and nearby gas/oil pipeline has been a topic of growing interest for many years. When pipelines are located in shared row with power lines, the pipeline can incur high induced voltages and currents due the AC interference. The induced voltage on pipeline can be dangerous for operator to touch the pipeline as well as pipe corrosion can result from AC discharge. This research evaluates and analyzes the electromagnetic interference effects on oil and gas buried pipelines created by the nearby high voltage transmission lines. The aim is to evaluate the AC corrosion likelihoods of pipelines and suggest proper mitigation solutions. Voir les détails

Mots clés : AC interference, Induced Voltages, Electric Power Transmission Lines, pipeline, AC Corrosion, Corrosion protection.

Pipelines Corrosion Due to the Electromagnetic Pollutioncaused by the High Voltage Power Lines

M. Ouadah, O. Touhami, R. Ibtiouen, A. Bouzida, S. Bouyegh, D.Allou, A.Haddad  (2017)
Publication

This paper studies the effect of theelectromagnetic pollution caused by the high voltage powerlines on the corrosion of the buried pipeline. In this objective,the finite element method (FEM) was used to calculate themagnetic field distribution and the induced current densitiesin the buried pipeline caused by both horizontal and verticalconfiguration of the HVPL during steady state conditions. Inorder to diagnose the effect of the electromagnetic pollutionon the corrosion of the pipeline, the electrochemicalimpedance spectroscopy (EIS)measurements were used tocharacterize the corrosion polarization properties of X70 steelin simulated soil at various AC current densities. The resultsshow that, the electromagnetic pollution caused by the highvoltage power lines affect the electrochemical characteristicsof the X70 steel pipeline and accelerate the corrosion of thepipeline. Voir les détails

Mots clés : Electromagnetic pollution, high voltage power line, induced current density, X70 steel pipeline, corrosion, Finite Element Method, Electrochemical impedance spectroscopy

Method for diagnosis of the effect of AC on the X70 pipeline due to an inductive coupling caused by HVPL

M.Ouadah, O.TOUHAMI, R.IBTIOUEN, M.Zergoug  (2017)
Publication

The inductive coupling between high-voltage power lines (HVPL) and buried pipelines has been an important research subject over the last decades. This coupling may result in alternating current (AC) on pipelines that may pose a serious threat to the pipelines due to corrosive effects and the cathodic protection (CP) performance. A method to investigate the effects of the induced AC density on the corrosion and the CP performances of the X70 steel buried pipeline due to the inductive interference caused by HVPL is proposed in this study. The method is based on the corrosion parameters of the X70 steel pipeline obtained by electrochemical measurements such as Tafel slopes, corrosion current densities, and corrosion potentials. These parameters were used as boundary conditions in the elaborated CP model. The results showed that, firstly, the induced AC density affects the electrochemical characteristic of the X70 steel and accelerates the corrosion of the pipeline. On the other hand, the impressed current cathodic protection is incapable of maintaining the CP potential level. However, some technical solutions were proposed to prevent the pipelines from AC corrosion and maintain the CP potential to an acceptable level. Voir les détails

Mots clés : electrochemical analysis, interference, chemical variables measurement, power cables, steel, electric current measurement, Corrosion protection, pipelines

A new time–frequency method for identificationand classification of ball bearing faults

I. Attoui, N. Fergani, N. BOUTASSETA, B. Oudjani, A. Deliou  (2017)
Publication

In order to fault diagnosis of ball bearing that is one of the most critical components ofrotating machinery, this paper presents a time–frequency procedure incorporating a newfeature extraction step that combines the classical wavelet packet decomposition energydistribution technique and a new feature extraction technique based on the selection ofthe most impulsive frequency bands. In the proposed procedure, firstly, as a pre-processing step, the most impulsive frequency bands are selected at different bearing conditionsusing a combination between Fast-Fourier-Transform FFT and Short-Frequency Energy SFEalgorithms. Secondly, once the most impulsive frequency bands are selected, the measured machinery vibration signals are decomposed into different frequency sub-bands byusing discrete Wavelet Packet Decomposition WPD technique to maximize the detectionof their frequency contents and subsequently the most useful sub-bands are representedin the time-frequency domain by using Short Time Fourier transform STFT algorithm forknowing exactly what the frequency components presented in those frequency sub-bandsare. Once the proposed feature vector is obtained, three feature dimensionality reductiontechniques are employed using Linear Discriminant Analysis LDA, a feedback wrappermethod and Locality Sensitive Discriminant Analysis LSDA. Lastly, the Adaptive NeuroFuzzy Inference System ANFIS algorithm is used for instantaneous identification andclassification of bearing faults. In order to evaluate the performances of the proposedmethod, different testing data set to the trained ANFIS model by using different conditionsof healthy and faulty bearings under various load levels, fault severities and rotatingspeed. The conclusion resulting from this paper is highlighted by experimental resultswhich prove that the proposed method can serve as an intelligent bearing fault diagnosissystem. Voir les détails

Mots clés : Vibration signal processing Bearing fault diagnosis Bearing faults LDA, LSDA, ANFIS, WPD