Liste des publications

Nombre total de résultats :688
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Effect of heat treatment on surface hardness and tribologicalbehavior of XC38 steel—approach by the experiments plans

M Bourebia, S Meddah, H Hamadache, A Taleb, A Gharbi, L Laouar  (2019)

This work aims at predicting the micro-hardness of XC38steel using the experiments plans as well asstudy of tribological behavior of thissteel. The heat treatments were considered by adopting thefactorial plans 22 methodology at two factors (temperature ‘T’ and holding time ‘t’), each at two levels(-1, +1). The results obtained allowed lead to a mathematical model predicting the micro-hardness‘Hv’ in every point of the study field. Moreover, the curves of the responses surfaces clearly show theinfluence of two factors studied (T, t) on ‘Hv’. Mechanical characterization of treated samples showedasignificant increase in the micro-hardness, which achieve to 76% for the treated sample at 850 °Cduring 2 h compared to untreated state. An investigation of wear tracks morphology shows thatfriction under a load of 10 N results in predominant adhesive wear, while a load of 2 N favorabrasive wear. Voir les détails

Mots clés : heat treatment, factorial plans, prediction, superficial hardness, tribological behavior

Characterization of the Polylactic acid stretched uniaxial and annealed by Raman spectrometry and Differential scanning calorimetry

A. Bouamer, N. Benrekaa, A.Younes, H. Amar  (2019)

In this work, we have been interested in the characterization of the effect of heat treatment and mechanical treatment on the crystallinity of polylactic acid (PLA) film by two techniques, DSC and Raman spectroscopy. The results obtained by the DSC for the stretched film shows the appearance of a broad peak of crystallization around 120 °C, a rise in melting peak in a significant way, which shows that the uniaxial stretching has increased the crystallinity of the PLA, whereas for the annealed film appearance of a double melting peak. The result obtained by Raman spectroscopy shows new peaks appears at 922 cm−1 and 540 cm-1 after stretching and annealed process, indicating the crystallization process. Voir les détails

Mots clés : PLA, glass transition, Raman spectroscopy, DSC

Remaining Life Estimation of the High Strength Low Alloy Steel Pipelines by Using Response Surface Methodology


This paper presents a probabilistic study to estimate the remaining lifespan of cracked steel pipeline by using the response surface technique. The purpose is to assess the reliability index of the high strength low alloy steel (HSLA) pipelines for a limit state function without closed-form. The implicit objective function is approximated by a polynomial representing a quadratic response surface and the assessment of the failure probability is obtained using Second order reliability method (SORM). The presence of a semi-elliptical crack defect in the longitudinal direction of the pipe steel will intensify the stress field at the crack tip and will decrease the limit state function. Exhaustive and costly tensile and Charpy V notch tests prepared from the longitudinal direction of the parent tube were achieved in order to study the mechanical behavior of API X70 steel grade and integrating the uncertainties of the engineering model parameters through their probabilistic densities. The assessment of the stress intensity factor is conducted by using the finite element methods. The estimation of the reliability index and the probability of failure are carried out by coupling the mechanical model, and the finite element method based on the commercial code ABAQUS. This coupling based on the response surface methodology, could be used as a decision making support for any repair or replacement of the damaged pipeline. Voir les détails

Mots clés : Reliability, Elliptical crack, Response surface, Uncertainties

Inspections, statistical and reliability assessment study of corroded pipeline

O. Bouledroua, D. ZELMATI, M. HASSANI  (2019)

The purpose of this work is to examine some points of views on the burst pressure standards assessment for a pipeline with internal and/or external corrosion defects. The proposed work contains three major parts. First, we used several analytical and numerical methods with the use of Ansys Software. The goal is presenting different aspects concerning burst pressure standards computation of real burst test. The second part shows an experimental study in order to check the inspections standards using an intelligent pig tool over a 48?km of a pipeline located in Algeria. All detected defects in the corroded pipeline are statistically analyzed. The final part, the reliability index β of the corroded pipeline subjected to internal pressure is estimated by using the SORM reliability approach. Voir les détails

Mots clés : Corroded pipeline burst test, Probability of failure, Failure assessment diagram, Finite Element Analysis

Real-Time Switches Fault Diagnosis for Voltage Source Inverter Driven Induction Motor Drive

H. MERABET, T. BAHI, K. Bedoud, D. DRICI  (2019)

Induction machine is the frequently used for electrical drive applications in almost many industrial processes due to its simple and robust construction. Speed control of induction machine is required depending on the type of application. Speed of the induction motor can be varied by varying frequency or by variation of the terminal voltage. Variable voltage can be fed to induction machine using the voltage source inverter which is found efficient technique of controlling induction motor drive. The potential faults that occur in inverter are the open and short circuit switch fault. The cost of this schedule can be high, and this justifies the development of fault diagnostic methods. In this paper we present a reliable strategy for diagnosis and detection of open and short circuit switch faults in plush width modulation of voltage source inverter (PWM-VSI) using the fuzzy logic approach. The principle of the proposed approach is based on the acquisition of stator currents, to calculate the average absolute values of currents (AAVC), which allows the real-time detection and localization of inverter IGBT open or short-circuit faults using just the motor phase currents. A model of the system is built using MATLAB/SIMULINK. Simulation results are presented showing the monitoring approach performance under distinct operating conditions. Voir les détails

Mots clés : open circuit fault, short circuit fault, Fuzzy logic, modeling, simulation

Propriétés Optique de TiO2 et Application de la Méthode de Swanepoel pour la Détermination de l’Épaisseur Optique et de l’Indice de Réfraction

K. Bedoud, H. MERABET  (2019)

Dans ce travail, des nano-films de dioxyde de titane « TiO2 » ont été déposés par pulvérisation cathodique en utilisant une cible en céramique de Ti pur de 3" de diamètre et 0,250" d'épaisseur avec une pureté de 99,99% sur des substrats en verre à des épaisseurs (e) différents. Nous visons par ce travail d’étudier l’effet de l’épaisseur sur les propriétés optiques de TiO2 nano films. Pour cela, nous avons utilisé la spectroscopie de transmittance optique UV-Visible pour la caractérisation optique. La variation du gap optique des films est inversement proportionnelle à la variation de l’épaisseur de 3,6 eV à 3,8 eV, respectivement. Pour la détermination de l'indice de réfraction et l'épaisseur du film nous avons utilisé la méthode proposée par Swanepoel, qui s’articule sur l’utilisation des franges d’interférence. On observe que, l'indice de réfraction n augmente avec l’augmentation de l'épaisseur de la couche déposée. Voir les détails

Mots clés : couches minces, pulvérisation, semi-conducteur, TiO2, nano-films, UV-Vis, épaisseur, indice de réfraction, Swanepoel

Study of Optical and Morphological TiO2 Nano-Films Properties Deposited by MagnetronSputtering on Glass Substrate

K. Bedoud, H. MERABET, L. Alimi  (2019)

In this paper, TiO2 nano-films were deposited by RF magnetron sputtering using a TiO2ceramic target of pureTi of 3" diameter and 0.250" thickness with a purity of 99.99%, onto heated glass substrates in a temperature range of200 to 450°C. This study determines the temperature effect on the structural, optical and morphological properties ofTiO2 nano-films. For this, we used X-ray diffraction for structural characterization and optical transmission spectroscopyUV-Visible for optical characterization and atomic force microscopy (AFM) for morphological characterization of thefilms produced. The (101), (400), (112), (200), (105), (211), (213), (204) peaks of the anatase structure and the (210),(102), (-112) (710) peaks of the monoclinic structure are observed. In addition, the peaks are sharp and intense whichimplies a good crystalline structure. Otherwise, the films optical gap variation is proportional to the temperature variationfrom 3,9eV to 3,92 eV for T=200°C and T=450°C, respectively. The surface roughness of TiO2 nano-films range from1,031nm to 4,665nm. Voir les détails

Mots clés : Thin films, sputtering, semiconductor, TiO2 nano-films, gas sensors, nano-films, RF magnetron sputtering, DRX, UV-Vis, AFM.

Magnetic and structural Behavior of Fe-CoO NanocompositesMechanically Milled

A.Younes, M.Khorchef, A.BOUAMER, H.Amar  (2019)

The Fe60(CoO)40 nanostructured alloys have been prepared from pure iron and cobaltoxide powders by mechanical alloying technique within a high energy planetary ball-mill.Morphology, microstructural and magnetic properties of this powder were investigated by a Scanning Electron Microscope (SEM), X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM). The effect of time of milling on magnetic behaviour of Fe(CoO) nanostructured composite has been investigated. Apparition of new phase polycrystallinesample having a size in the range of 12 and 26 nm, it is confirmed by X-ray diffraction testing.The enhanced magnetic properties and structural behaviour of the nanoparticle are due by the diminution of size of crystallite. After 40 hours of milling, the appearance of spinel structureof CoFe2O4. The reduction in particle size leads to a significant increase in magnetic hardening, the coercive field at room temperature increases from 6 Oe to 208 Oe Voir les détails

Mots clés : FeCoO nanostructured, Magnetic Properties

Development of photovoltaic cell models using fundamental modeling approaches

Mohammed Aidoud, Chams-Eddine Feraga, Mohcene Bechouat, Moussa Sedraoui, Sami KAHLA  (2019)

In this paper, three advanced modelling approaches will be performed to well describe the actual behavior of photovoltaic (PV) cells, in which some total solar irradiance changes are considered. The first one uses a specific solar cell provided by the Sim-Electronics tool of the Matlab software. It is used to simulate the actual behavior of PV cells instead of the conventional electrical circuit based on either single or double diodes. The second approach adopts some physical components provided by the Simscape library to reach the same above mentioned goal. The third approach uses the Simulink blocks to build the mathematical equations describing the PV cell behavior, in which some mathematical operators and functions are used. The three proposed models have the ability to predict the actual behavior of PV cells under different weather conditions. This can improve the extraction of the maximum power and contribute even to the synthesis of the appropriate controller. The performances assessment of each proposed model is established in term of the provided output power as well as the generated current and voltage. Voir les détails

Mots clés : PV cell, Simulink, Simscape, Simelectronics, PV mode

Modeling and Fuzzy MPPT Controller Design for Photovoltaic Module Equipped with a Closed-Loop Cooling System

M. BECHOUAT, M. Sedraoui, C-E. Feraga, M. Aidoud, S. Kahla  (2019)

Electrical energy generated by a photovoltaic (PV) panel depends heavily on two climatic conditions: total solar irradiance and absolute temperature. If high intensity of the solar illumination contributes positively to increasing electrical power, a high degree of absolute temperature has, by contrast, a negative effect on its electrical characteristic. In this paper, the electrical efficiency provided by a conventional PV panel is enhanced using the proposed photovoltaic thermal (PVT) panel. The latter contains serpentines fed by a water tank, which allows cooling its PV cells at high temperature. Accordingly, the desired enhancement needs two main requirements: an efficient PVT panel model that accurately describes the actual PVT panel behavior and an efficient controller that correctly tracks the maximum power point tracking (MPPT). For this reason, a number of experimental test data is firstly recorded from an actual ISOFOTON I-50-PVT module under different climatic conditions. Afterward, the recorded data are fitted by the Curve Fitting Toolbox (CF-Tool), creating therefore a 2-dimensional lookup table, used in the following step. Next, the fuzzy logic control (FLC) strategy is employed to synthesize the proposed MPPT-FLC controller, which should ensure a good extraction of the maximal electrical power. To validate the effectiveness of the proposed MPPT-FLC controller based on a 2-dimensional lookup table, the obtained performance is compared, in terms of electrical power and duty cycle, to those provided by an MPPT-FLC controller for a conventional PV panel in various climatic conditions. Voir les détails

Mots clés : Photovoltaic thermal system, 2-Dimensional lookup table, fuzzy logic control, Maximum Power Point Tracking