Liste des publications

Nombre total de résultats : 541
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Optimization of TIG Welding Process Parameters for X70-304LDissimilar Joint Using Taguchi Method

Mohamed Farid Benlamnouar, Mohamed HADJI, Riad BADJI, Nabil Bensaid, Tahar Saadi, Yazid Laib dit Laksir, Sabah Senouci  (2019)
Publication

The optimization of mechanical properties of the welded joints requires a statisticalapproach such as Taguchi experimental designs associated with experimental techniques andlaboratory characterizations. The aim of this work is to propose a method of optimization of themechanical performances of a TIG dissimilar welding of two grades of steels: a high strength lowalloy steel X70 and an austenitic stainless steel 304L. The experimental designs were chosenaccording to the Taguchi method L9. The metallurgical characterization includes opticalmicroscopy, SEM microscopy, EDX analyses and mechanical tests to establish a relationshipbetween welding parameters, microstructures and mechanical behavior in different dissimilar weldregions. The results showed that the hardness is more strongly related to microstructural evolutionthan tensile strength of dissimilar joint. It was found that gas flow is the main significant TIGwelding parameter affecting dissimilar weld characteristics. Voir les détails

Mots clés : hardness, tensile test, ANOVA, Dissimilar welds, Taguchi method

Annealing duration influence on dip-coated CZTS thin films properties obtained by sol-gel method

M.C. Benachour, R. Bensaha, R. Moreno  (2019)
Publication

The effect of annealing duration on structural and optical properties of dip-coated crystallineCZTS thin films was studied. The obtained samples were investigated by several techniques suchas XRD, Raman spectroscopy, SEM, UV–vis spectroscopy and Photoluminescence. Being con-firmed by Raman spectroscopy, XRD analysis reveals the formation of kesterite tetragonal phasewith preferential orientation along (112) direction. The grain size tends to increase as the an- nealing duration increases, a result confirmed by SEM. The last shows smooth, uniform, homo-geneous and densely packed grains. Optical measurement analysis reveals that layers have re- latively high absorption coefficient in the visible spectrum with a band gap reduction of1.62−1.50 eV which is quite close to the optimum value for a solar cell. The photoluminescence distinguishes broad bands that have maximums of intensity limited between 1.50 and 1.62 eV,corresponding to the optical band gap of the CZTS.Kesterite,Sol-gel,Thin-film,Dip-coating,CZTS,Photoluminescence Voir les détails

Mots clés : Kesterite, sol-gel, Thin-film, Dip-Coating, CZTS, Photoluminescence

Annealing duration in?uence on dip-coated CZTS thin ?lms properties obtained by sol-gel method

M. C. Benachour, R. Bensaha, R. Morenoc  (2019)
Publication

The e?ect of annealing duration on structural and optical properties of dip-coated crystallineCZTS thin ?lms was studied. The obtained samples were investigated by several techniques suchas XRD, Raman spectroscopy, SEM, UV–vis spectroscopy and Photoluminescence. Being con-?rmed by Raman spectroscopy, XRD analysis reveals the formation of kesterite tetragonal phasewith preferential orientation along (112) direction. The grain size tends to increase as the an- nealing duration increases, a result con?rmed by SEM. The last shows smooth, uniform, homo-geneous and densely packed grains. Optical measurement analysis reveals that layers have re- latively high absorption coe?cient in the visible spectrum with a band gap reduction of1.62−1.50 eV which is quite close to the optimum value for a solar cell. The photoluminescence distinguishes broad bands that have maximums of intensity limited between 1.50 and 1.62 eV, corresponding to the optical band gap of the CZTS. Voir les détails

Mots clés : Kesterite, sol-gel, Thin films, Dip-coating CZTS, Photoluminescence

Theoreticalmodelling for calculation of the energydensities of adsorption sites using inverse gaschromatography

A.BOUHANK, L.BENCHEIKH  (2019)
Publication

The inverse gas chromatography is used to determine the energy densities of theadsorption sites of the stationary solid phase. The use of this technique is old anddates back to the 1940s. The many possibilities offered by this method are describedin several works. This work is an attempt to explore some adsorption local isothermmodels in order to determine the energy density of the adsorption sites. It involves theuse of integral equations of the first kind which are known to be numerically instable.These integral equations were solved by two different methods of solution. One isbased on the use of Taylor series expansions and the other uses the Stieltjes transform.Some interesting theoretical and numerical results are presented. Voir les détails

Mots clés : adsorption, Integral equations, Adsorption isotherms, energy

Magnetic and structural Behavior of Fe-CoO Nanocomposites Mechanically Milled

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

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 aScanning Electron Microscope (SEM), X-ray diffraction (XRD) and Vibrating samplemagnetometer (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 thediminution 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 magnetichardening, the coercive field at room temperature increases from 6 Oe to 208 Oe Voir les détails

Mots clés : Fe60(CoO)40 nanostructured alloys, Mechanical Alloying, Magnetic Properties

Reliability of the High Strength Pipeline Steelunder Corrosion Defect

O. GHELLOUDJ, D. ZELMATI, A. GHARBI, D. BERDJANE, C.D. RAMOUL, T. CHOUCHANE  (2017)
Publication

The demand of energy based on hydrocarbons, such as gas and oil, requires construction of more and more newpipelines. Therefore, the assessment of the remaining life of these pipeline structures became increasingly importantto ensure the continuity of production and distribution operations. The reliability of these industrial facilities islargely conditioned by specific characteristics of each system, by its conditions of use and its environment. Generally,the causes of deterioration of hydrocarbon transportation pipelines are related to the presence of apparent defects(pinholes, cracks, corrosion, etc). This study is aimed to estimate the reliability of pipeline structures. The B31Gmechanical model of degradation was used to assess the probability of failure through dimensions of defects. Voir les détails

Mots clés : Reliability, pipeline, Defects, Mechanical Model

Study of The Reliability of A Composite Used In The Knee Prosthesis

L. Alimi, M. Boulkra, N. Sassane, S. Boukhezar, M. HASSANI, K. Bedoud, K. BEY  (2019)
Publication

In orthopedic surgery, the effectiveness of the implants used, such as hip and knee prostheses, depends mainly on their geometries and the type of loading to which they are subjected. In this work a probabilistic approach is chosen to study the reliability of a composite structure used in the manufacture of knee prostheses. The purpose of integrating reliability concepts is to consider uncertainty in several aspects including loading and material properties. The reliability index β is an excellent indication of durability and safety for given operating conditions. β is obtained using failure probability and a mechanical model. The critical stress intensity factor (Kc) is adopted as a criterion to the maximum limit of a numerically calculated KI. The results presented are discussed according to the length of the crack (a), and the limit load used. Voir les détails

Mots clés : Reliability analysis, critical stress intensity factor, crack length, load, reliability index

Experimental study of chemically aged HDPE pipe material in toluene-methanol mixture and distilled water

Latifa ALIMI, Kamel CHAOUI, Nacira Hamlaoui, and Khouloud Bedoud  (2019)
Publication

Studying the aging phenomenon of plastic pipes presents simultaneously an economic achievement and a technical challenge for water and natural gas transportation systems. Ver y often, they are exposed to aggressive environmental agents such as UV rays, ambient oxygen, acids, bases and some other so lvents, altering the material microstructure, its physical and chemical properties. The high density polyethylene (HDPE) material degradation and loss of performance are usually the consequence of unwanted changes in mechanical behaviors leading to lower resistance. In this s tudy, we examine the effects of distilled water (DW) and a mixture of toluene-methanol (TM) in contact with an HDPE pipe. Morphological properties such as crystallinity and oxidation induction time (OIT) are in vestigated using DSC method. Tensile tests and thermal analysis show that the TM mixture is much more absorbed by the resin as compared to DW. An increase in crystallinity is observed as established from literature for other organic solutions. Finally, the study gives an idea about property variances and their evolution as a function of the pipe thickness which c an be used as an estimation of the structural heterogeneity of the product. Voir les détails

Mots clés : Pipe; HDPE; Aging; Distilled Water; Toluene-Methanol Mixture; Crystallinity; OIT

Feedback linearization control based particle swarm optimization for maximum power point tracking of wind turbine equipped by PMSG connected to the grid

Youcef Soufi, Sami KAHLA, Mohcene Bechouat  (2016)
Publication

The main problem regarding wind power systems is the major discrepancy between the irregular character of the primary source (wind speed is a random, strongly non-stationary process) and the exigent demands regarding the electrical energy quality. This paper presents a feedback linearization controller based particle swarm optimization for maximum power point tracking of wind turbine equipped by PMSG connected to the grid, the proposed method which aims at maximizing the power captured by WECS. In order to drive the system to the optimal operating point using the selection of the controller parameters with particle swarm optimization. The obtained simulation results with a variable wind profile show an adequate dynamic of the conversion system using the proposed approach. Voir les détails

Mots clés : Wind turbine, Maximum Power Point Tracking, Feedback linearization control, Particle Swarm Optimization (PSO), Wind Energy Conversion System (WECS)

Particle swarm optimization based sliding mode control of variable speed wind energy conversion system

Youcef Soufi, Sami KAHLA, Mohcene Bechouat  (2016)
Publication

This paper proposes a particle swarm optimization based sliding mode control of squirrel cage induction generator of a variable speed wind energy conversion system. The key feature of sliding mode control is a wisely chosen sliding surface which allows the turbine to operate more or less close to the optimal regimes characteristic. Optimal control parameters which are the convergence speed to the sliding-mode, the slope of the surface and the switching component amplitude of SMC are determined using particle swarm optimization approach. The simulation results prove the viability of the proposed control structure. Voir les détails

Mots clés : Squirrel Cage Induction Generator (SCIG), Wind Energy Conversion System (WECS), Sliding Mode Control (SMC), Particle Swarm Optimization (PSO)