Liste des publications
Comparison and statistical validation of a model of a photovoltaic module
The study presented in this paper includes a comparison, and a statistical validation. The results that are obtained by a numerical simulation in MATLAB are compared with the experimental results that are taken from the Unit of Applied Researchin Renewable Energy "Ghardaïa" (URAERG) (Experience in the fieldof solar energy). The work is to exploit the experimental dataobtained by exposing the solar cells (panel BP3160W) to light(sunlight), wherever the place of use and the operating conditions. The purpose of this study was to evaluate the model of single diode proposed by Walker of University of Queensland, Australia, uses the electric model with moderate complexity. The numerical results are presented relating to the current-voltage characteristics and power-voltage; during a change of weather conditions such as light, and temperature. To compare, objectively, the performance of the model with the diode modeled using experimental data, statistical indicators proposed by Chang and Hanna (2004) were calculated for different measurement points of light and temperature; the analysis shows that the results for the current and the power reflect the physical reality. Note; however, that the model results are in a very good agreement with experimental measurements. Voir les détails
Mots clés : Model of single diode, solar panels, Matlab, statistical validation
Optical and Photo-Electrochemical Properties of Conducting Polymer/Inorganic Semiconductor Nanoparticle
Optical and photoelectrochemical properties of polybithiophene Poly(bTh) films electrochemically synthesized and modified with incorporation of silicon nanoparticles (n-Si or p-Si) dispersed in the electrolytic during polymerization were studied. The characterisation of these modified surface electrodes by Poly(bTh)+n-Sior Poly(bTh)+p-Si, was carried out by using the photocurrent measurements and UV-visible spectroscopy. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) have been used to investigate the electrochemical behaviour of theresulting materials. The results show that the photosensitive composite materials have good photoelectrochemical and optical properties, and it can be used as material for the photovoltaic cells applications. Voir les détails
Mots clés : Organic-inorganic composite, polybithiophene, Silicon, electroactivity, photoelectrochemistry.
Mechanical properties study in extruded HDPE-80 pipe wall used fornatural gas distribution
Polymers represent a remarkable family of materials becauseof the variety of products that it is possible to design with and the different implementationprocesses offered. The use of these materials allowed to acheive substantial gains onassociated costs, service times and repair. Despite the acceptance of polyethylene as an economicalternative for pipes networks, safety remains a fundamental issue, and it requiresthe ability to determine intrinsic properties as a function of the service conditions requiredby the design and the use. This study deals with the determination of the mechanical behaviourof an HDPE resin through the entire pipe wall thickness. Standard testing specimenshave been manufactured under specific conditions in the longitudinal direction accordingto ISO-527. The mechanical properties are measured in traction using a computer-driventesting machine. The results indicate that there is a clear evolution of the mechanical propertiesthrough the pipe wall, which confirms the bahaviour observed in other studies ofpolyethylene filaments tested under the same conditions. These variations are attributed tomorphological gradients and the evolution of internal stresses imparted by the extrusionprocess. Voir les détails
Mots clés : Mechanical caracterization; polyethylene pipe; elastic modulus; extrusion; traction
ETUDE DES PROPRIETES MECANIQUES DES COUCHES DE MOLYBDENE PROJETEES THERMIQUEMENT SUR UNE FONTE GRISE
The coatings obtained by thermal spraying are used in order to meet the most stringent industrial requirements in the fields of application wider. The molybdenum coating is one good wear resistance which used in several mechanical applications. In this work, we have studied the mechanical properties of molybdenum coating deposited using thermal spraying on gray cast iron with lamellar graphite. After optimization of spraying parameters, the microstructure has been studied using the optical microscopy, scanning electron microscopy and the X-ray diffraction. Also, the mechanical properties such as microhardness and elastic properties like elastic modulus using nanoindentation test have been evaluated on cross section sample polished. The weight loss has been studied using the abrasive wear test varying the normal load. The results obtained have showed an improvement the mechanical properties of gray cast iron after deposit of molybdenum. Voir les détails
Mots clés : Thermal Spraying, Molybdenum Coating, gray cast iron, wear, mechanical properties
A Comparative Study of Analytical,Iterative and Bayesian Reconstruction Algorithms in Computed Tomography(CT)
These Images of the inside of the human body can be obtained using tomographic acquisition and processing techniques. In particular, these techniques are commonly used to obtain X-ray images of the human body. The reconstructed images are obtained given a set of their projections, acquired using reconstruction techniques. A general overview of analytical and iterative methods of reconstruction in computed tomography (CT) is presented in this paper, with a special focus on Bayesian algorithms. The simulated results are compared using quality measurements for various test cases and conclusion is achieved. Through these simulated results, we have demonstrated that the Bayesian approach provides the best image quality and the small values of the quality measurements. Voir les détails
Mots clés : Computed tomography, Bayesian approach, reconstruction techniques.
Object recognition using Radon transform based RST parameter estimation
In this paper, we propose a practical parameter recovering approach, for similarity geometric transformations using only the Radon transform and its extended version on [0, 2π]. The derived objective function is exploited as a similarity measure to perform an object recognition system. Comparison results with common and powerful shape descriptors testify the effectiveness of the proposed method in recognizing binary images, RST transformed, distorted, occluded or noised. Voir les détails
Mots clés : RST parameters, radon transform, object recognition
Combining RBF-PCA-ReliefF Filter for a better diagnosis performances in rotating machines
Monitoring and faults diagnosis in rotating machinery is a current research field. In this direction the use of pattern recognition combined with non-destructive testing techniques such as' vibration analysis and signal processing can be very useful. In this paper was proposed, a diagnosis method of rotating machinery using vibration signatures with a Radial Basis Function classifier. The recorded signals were preprocessed with a Wavelet Decomposition and indicators were extracted both in temporal and frequency domain. To improve diagnosis performance, two techniques for dimension reduction of indicators space are combined; Principal Component Analysis and the filter ReliefF. The method was tested on real signatures from a vibration test bench, operating under several conditions, the results showed the interest to look closely at the choice of indicators in order to have best diagnosis performance. Voir les détails
Mots clés : diagnosis, Rotating machinery, principal component analysis, radial basis function
Improving the sensitivity of Raman signal of ZnO thin films deposited on silicon substrate
Raman spectroscopy results of DC reactive sputtering of ZnO thin films deposited on silicon substrates are reported. Monocrystalline silicon wafers are frequently used as substrates for thin film deposition, and when working on thin films materials of rather low Raman cross-sections such as ZnO, it is difficult and even sometimes hopeless to extract the Raman information relevant to the film from the silicon signal.In this paper, we show that using a 457 nm wavelength of the laser excitation combined with the effect of silicon Raman selection rules through convenient orientation of the silicon substrate, the 520 cm-1 Si signal can be sufficiently attenuated to give access to the ZnO Raman information, whatever the important difference of intensity between them. Voir les détails
Mots clés : Raman spectroscopy, Thin films, Silicon, Zinc oxide, DC reactive sputtering deposition
STYDY OF MECHANICAL PROPERTIES OF MOLYBDENUM COATINGS DEPOSITED BY THERMAL FLAME SPARYING ON GRAY CAST IRON
Thermal spraying coatings are used to meet the most stringent industrial requirements in the wider of application. The molybdenum coatings present a good wear resistance which used several mechanical applications. In this work, we studied the mechanical properties of molybdenum coating deposited using thermal flame spraying on gray cast iron with lamellar graphite. After optimization of the spraying parameters, the microstructure was investigated using optical microscopy, scanning electron microscopy and X-ray diffraction. The mechanical properties obtained by microhardness and nanoindentation tests were evaluated on a polished cross section. The mass loss was measured using the abrasive wear test at varying the normal load. The results showed an improvement the mechanical properties of gray cast iron after deposition of molybdenum with wire-flame spraying. Voir les détails
Mots clés : Thermal Spraying, Molybdenum Coating, mechanical properties, Nanoindentation, wear.
Influence of G729 Speech Coding on Automatic Speaker Recognition in VoIP Applications
Influence of G729 Speech Coding on Automatic Speaker Recognition in VoIP Applications Voir les détails
Mots clés : Automatic speech recognition (ASR) Universal background model (GMM-UBM) G729 VoIP Resynthesized speech T-norm scoring