Liste des publications
Design and Real Time Implementation of Three-PhaseThree Switches Three Levels Vienna Recti?er Based onIntelligent Controllers
This paper treats the control of multilevel rectifier by applying the soft computing technique represented by the fuzzy logic. This latest, provides an inexpensive solution for controlling the ill-known complex systems, while relying on the imitation of human reasoning. In our case, the proposed intelligent controller aims at eliminating the current line harmonics, guaranteing an improved power factor, reducing the output voltage ripple and ensuring the balance between the two voltages across the two capacitors of Vienna rectifier. In order to evaluate the performance of the proposed control for Vienna rectifier, a comparative study in real time via the dSPACE card 1104 has been carried out between the traditional approach based on the conventional controllers and the new method using an intelligent controller. The experimental results confirm that the modified control approach has guaranteed a good quality of source currents in phase with the grid voltages and operation of the studied system with a power factor very close to unity. Furthermore, only one fuzzy controller used has ensured the regulation of the DC bus voltage, the minimization of the undulations for the two partial voltages and the improvement of the error of the voltage balance for the Vienna rectifier. Voir les détails
Mots clés : Vienna rectifier, Fuzzy logic controller, DC bus voltage ripple, Total harmonic distortion, Power factor correction
DIAGNOSIS OF ROTOR FAULT USING NEURO-FUZZY INFERENCE SYSTEM
The three-phase induction machine (IM) has a large importance and it is widely used as electromechanical system device, and because of their; robustness, reliability, and simple design with the well developed technologies. In spite of all cited advantages, the induction machines are suscptible to various types of electrical and mechanical faults that can lead easly to excessive downtimes, which can lead to tuge losses in terms of maintenance and production. This work presents a reliable approach for diagnosis and detection of broken bar faults in induction machine. The detection of faults is based on monitoring of the stator current signal. Also the calculation of relative energy value for each level of signal decomposition is determinated by using package wavelet, and this method will be useful as data input of Adaptive Neuro-Fuzzy Inference System (ANFIS). In the ANFIS approach the adaptive Neuro-Fuzzy inference system is able to identify the rotor of induction machine state with high precision.This method is applied by using the MATLAB®/Simulink software. Voir les détails
Mots clés : Induction machine, Neuro-Fuzzy inference system., Inductoion Machine
Effect of Grain Size of Nano Composite on Raman and Magnetic Proprieties
Based Iron-cobalt alloys exhibit particularly interesting Raman and magnetic properties, with high Curie temperatures, the highest saturation magnetizations, high permeability, and low losses and is relatively strong and partial oxidation of Fe and Co. The cost of these alloys has confined them, since their discovery by Elmen in 1929, to applications where the volume is small and high magnetic performances are critical. Sintering is the procedure of formation and compaction of a material. We have prepared the nano crystalline alloy by the mechanical milling process in a high energy planetary ball-mill PM400. Morphological, micro-structural, magnetic characterizations of the powders milled several times were investigated by scanning electron microscopy, X-ray diffraction, vibrating manometers sample and Raman spectroscopy. The coercivity value increase during millingtime from 0.018 to 185.9 Oe and saturation magnetization value from 42.7 to 51.1 emu/g, respectively. Voir les détails
Mots clés : Mechanical Alloying, Nanostructured FeCo, Magnetic and Raman characterization
Computational Investigation of Droplets Behaviour inside Passive Microfluidic Oscillator
Recently, modeling immiscible fluids such as oil and water have been a classical research topic. Droplet-based microfluidics presents a unique platform for mixing, reaction, separation, dispersion of drops and many other functions. In this paper, we suggest a numerical CFD study of microfluidic oscillator with two different lengths of feedback loop. In order to produce simultaneous droplets of gasoil on water, a typical geometry that includes double T-junction is connected to the fluidic oscillator. Droplets production is computed by volume-of-fluid method (VOF). Flow oscillations of droplets were triggered by the Coanda effect of jet flow. The aim of work is to get a high oscillation frequency in the output of this passive device, the influence of hydrodynamics and physics parameters on the droplets frequency in the output of our microsystem is also investigated, the computational results show that, the length of feedback loop, operating pressure and interfacial tension have a significant effect on the droplets dynamic inside microfluidic oscillator. Across the range of low Reynold number, the droplets generation and its dynamics have been accurately controlled by adjusting applying pressure ratio of two phases. Voir les détails
Mots clés : Droplet, microfluidics, fluidic oscillator, CFD and VOF (volume of fluid method).
Diagnosis and classification using ANFIS approach ofstator and rotor faults in induction machine
Three-phase squirrel cage induction motors are one of the importantelements of the industrial production system, and are mostly used because oftheir robustness, reliability, relatively simple construction and their low cost.Nevertheless, during their function in different process, this machine types aresubmitted to external and internal stresses which can lead to several electricalor mechanical failures. In this paper, we proposed a reliable approach fordiagnosis and detection of stator short-circuit windings and rotor broken barsfaults in induction motor under varying load condition based on relative energyfor each level of stator current signal using wavelet packet decompositionwhich will be useful as data input of adaptive neuro-fuzzy inference system(ANFIS). The adaptive neuro-fuzzy inference system is able to identify theinduction motor and it is proven to be capable of detecting broken bars andstator short-circuit fault e with high precision. The diagnostic ANFIS algorithmis applicable to a variety of industrial process based on the induction machinefor detection and classified the any faults types. This approach is applied underthe MATLAB software®. Voir les détails
Mots clés : Induction machine, Detection, diagnosis, neuro-fuzzy, Monitoring
Complexity reduction of ultrasound sub-ultra-harmonic modeling by an input modified volterra approach
Contrast of echographic images has been highly improved by the injection of microbubbles, due to their nonlinear behavior. However, this contrast enhancement is limited by the nonlinear acoustic propagation in tissue. To overcome this drawback, sub and ultra-harmonic contrast imaging can be used, since only microbubbles can generate these components. Nonlinear modeling is a primordial step in the analysis of microbubble signals for sub and ultra-harmonic imaging. Nonlinear models like Volterra model has been applied in harmonic imaging to model harmonics optimally. However, it can model harmonics only. For sub and ultra-harmonic modeling, a multiple input single output (MISO) Volterra has been proposed. The aim of this study is to propose a simpler alternative for the modeling of sub and ultra-harmonics. We propose a modified single input single output (SMISO) Volterra model based on input demodulation. The model is tested using simulated and experimental signals. Results showed that sub and ultra-harmonics are modeled. The number of kernels is reduced to its half using SMISO model compared to MISO model. The relative mean square error between the simulated signal and the modeled signal with SMISO Volterra model is -15.8 dB and it is -60.7 dB for experimental signals. The computational time is reduced by a factor of 4 and 5 in simulated and experimental cases respectively. SMISO model can make easier the sub and ultra-harmonics modeling. Voir les détails
Mots clés : Non lineaire acoustics, contrast enhancement
Structural optical magnetic properties of Co doped -MoO3sprayedthin films.
this works deals with the synthesis of Cobalt doped MoO3thin films which were grown on glass sub-strates by the spray pyrolysis at 460?C. First, X-ray diffraction analysis shows an orthorhombic structurerelated to -MoO3allotropic variety with (020) and (040) preferred orientations. The surface topogra-phy performed by atomic force microscopy (AFM) shows that the grain size varies from 150 to 280 nm.Second, optical parameters, such as optical band gap, Urbach energy, refractive index and dielectricconstants were studied in terms of Co content. This optical study shows a direct transition of all pre-pared thin films and normal dispersion of the refractive index showing both Cauchy and Wemple &Di-dominico variations. On the other hand, PL measurements show transition bands mainly in blue andgreen domains related to band-to-band transitions as well as to oxygen vacancy in all films. Finally, mag-netic measurements at room temperature using vibrating sample magnetometer (VSM) technique reveala ferromagnetic behavior of such doped films. Voir les détails
Mots clés : MoO3, Thin films, optical properties, Magnetic Properties, Spray pyrolysis
Study of structural and thermal properties of SiO2 and Al2O3 in the Diatomite
Diatomite, also known as diatomaceous earth, is the naturally occurring fossilized remains of diatoms. Diatoms are single-celled aquatic algae. They belong to the class of golden brown algae known as Bacillariophyceae. Diatomite is a near pure sedimentary deposit consisting almost entirely of silica. The Greeks first used diatomite over 2,000 years ago in pottery and brick.In this work we determine the structural and thermal properties of SiO2 and Al2O3 in the diatomite using the plane wave method and linearized augmented (LAPW) in the functional theory of density (DFT).The potential for exchange and correlation is calculated by the generalized gradient approximation (GGA).Regarding thermal properties, we calculated the free enthalpy G, S entropy, specific heat C, thermal conductivity λ ..... etc of SiO2 and Al2O3 component. The temperatures used in this work are 1400, 1450 and 1500 respectively;The results are in good agreement with some experimental data. Voir les détails
Mots clés : DFT1, diatomite, thermal proprieties
Signal Quality Improvement Using a New TMSSE Algorithm:Application in Delamination Detection in Composite Materials
This paper introduces a novel method to improvethe quality of ultrasonic phased array signals for localizingwith accuracy delamination defects. The improvementis achieved by the introduction of a new threshold for theShannon energy. In first, we have applied the threshold modifiedS-transform algorithm (TMST) in the case of ultrasoundB-scan. Thereafter, we have adapted and applied the StransformShannon energy (SSE) algorithm in the field ofultrasonic testing. At last, we have proposed a novel algorithmbased on threshold modified S-transform and Shannonenergy (TMSSE) to increase the improvement of the ultrasoundB-scan. A simulation study has been carried outsimulating a composite material containing three defects indifferent positions in order to highlight the phenomenon ofdelamination. Experimental tests were performed on a sampleof carbon fiber reinforced polymer composite material(CFRP) with a delamination defect close to the front face.Both experimental and simulated results show that the proposedmethod can improve the quality of ultrasound B-scanwhich enhances the localization of delamination defects. Voir les détails
Mots clés : Ultrasonic signal
Corrosive effects of the electromagnetic induction caused by the high voltage power lines on buried X70 steel pipelines
This paper diagnoses the corrosive effects of the electromagnetic induction caused by double circuit high voltage power lines (HVPL) on the buried X70 steel pipelines. To achieve this objective, firstly the electromagnetic interference between the double circuit HVPL and the X70 steel pipeline (the distribution of the magnetic field and the induced AC current densities in the buried X70 steel pipeline) and the factors affecting this interference such as the vertical distance between the double circuit HVPL and the X70 steel pipeline, and the conductor phase sequence orientation were studied. Then, electrochemical measurements were used to characterize the corrosion polarization properties of X70 steel in simulated soil at various AC current densities. The results show that with an increase in the AC current density, the corrosion rate of the X70 steel increased, indicating that the induced AC current density has accelerated the corrosion degree of X70 steel, by comparison with that in the absence of the AC current density. We can conclude from these results that the electromagnetic induction caused by the double circuit high voltage power lines affects the electrochemical characteristic of the X70 steel pipeline and accelerates the corrosion of the pipeline. Voir les détails
Mots clés : Electromagnetic induction, high voltage power line, induced AC current density, X70 steel pipeline, corrosion, Finite element method.