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Nombre total de résultats : 1847
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Etude de quelques modèles pour le calcul des densitésénergétiques des sites d'adsorption en utilisant lachromatographie gazeuse inverse

BOUHANK Antar (2019)
Thèse de doctorat

L'application de la Chromatographie Gazeuse Inverse (CGI) pour la détermination desgrandeurs physico-chimiques qui caractérisent l'interaction entre une molécule sonde etunsupport chromatographique est déjà ancienne puisque les premiers travaux remontent auxannées quarante. Les nombreuses possibilités offertes par cette méthode sont décrites dansplusieurs ouvrages. On se propose dans ce travail d'explorer quelques modèles d'adsorptionlocales,à savoir l’isotherme d’adsorption de Langmuir générale et de Sips pour calculer ladensité énergétique des sites d'adsorption.Pour ce faire on s'appuie surdes méthodesanalytiques et numériques. Une des méthodes analytiques utilise la notion de transformée deStieltjes, alors que la méthode numérique est basée sur la discrétisation de l’équation intégraleen un système d’équations algébriques. Voir les détails

Mots clés : chromatographie gazeuse inverse, équation intégrale, transformée de Stieltjes, isotherme d’adsorption

Droplet Breakup Regime in a Cross-Junction Device with Lateral Obstacles

Tawfiq Chekifi  (2019)
Publication

Numerical simulation using Ansys Fluent code is performed, to investigate droplet generation in cross-junction based VOF method. Droplets of water are generated by the shear stress applied by continuous phase (oil), two configurations of cross-junction are suggested; the first is a simple model no modification is performed at the outer channel, while the second model is characterized by a lateral obstacle. we study the effect of velocity ratio, viscous parameter, interfacial tension, flow condition on droplet size and frequency, the effect of lateral obstacles on droplets generation is also focused and analysed. The numerical simulations showed that the velocity ratio and interfacial tension play a significant role in determining the droplet breakup and non-breakup. On the other side, the increase of flow rate ratio can be effectively used to decrease the droplet size. In addition, droplets produced in cross-junction with lateral obstacles are generally found to be larger than that produced with the first model. Moreover, the frequency of droplet production was increasing by increasing of flow rate ratio. The numerical results show very good agreements with previous numerical and experimental works for the growth of droplet breakup, size and frequency. Voir les détails

Mots clés : Water droplet, cross-junction, CFD, VOF, microchannel.

Real Time Implementation of Grid Connected Wind Energy Systems: Predictive Current Controller

N. Hamouda, B. Babes, S. Kahla, Y. Soufi  (2019)
Article de conférence

This work, suggests a new control strategy usingFinite-Control-Set Model-Predictive-Control (FCS-MPC) for thecontrol of a wind turbine system (WTS) based on PermanentMagnet Synchronous Generator (PMSG). The consideredcontroller is separated on two parts: FCS-MPC-based on thecurrent control loop for the single switch mode rectifier tooptimally release the maximum wind power, and FCS-MPCbased on the voltage control loop for the voltage source inverterto enhance the THD of grid currents. A wind energy systemprototyping platform was developed and accomplished in thelaboratory, and the experimental results are provided to verifythe performances of the considered FCS-MPC strategies. Voir les détails

Mots clés : Finite-Control-Set Model-Predictive-Control (FCSMPC), Permanent Magnet Synchronous Generator (PMSG), Wind Turbine System (WTS), Maximum Power Point Tracking (MPPT), Grid Connected, Experimental Results

A DC/DC Buck Converter Voltage Regulation UsingAn Adaptive Fuzzy Fast Terminal Synergetic Control

Noureddine Hamouda, Badreddine BABES, Mohamed MEZAACHE  (2019)
Article de conférence

In this paper, an adaptive fuzzy fast terminalsynergetic voltage regulation for DC/DC buck converter isdesigned based on recently developed synergetic theory and aterminal attractor method. The advantages of presentedsynergetic control include the characteristics of finite timeconvergence, insensitive to parameters variation and chatteringfree phenomena. Rendering the design more robust, fuzzy logicsystems are used to approximate the unknown parameters in theproposed controller without calling upon usual modellinearization and simplifications. Taking the DC/DC buckconverter in continuous conduction mode as an example, thealgorithm of proposed synergetic control is analyzed in detail. Allthe simulation results demonstrate the effectiveness and the highdynamic capability of the proposed AF-FTSC control techniqueover the FTSC strategy Voir les détails

Mots clés : synergetic control, fuzzy logic system, terminal technique, finite time convergence, DC/DC buck converter

Elaboration et caractérisation de couches minces d'oxyde dezinc dopées aux métaux pour des applicationsphotovoltaïques et en détection de gaz.

BOUGHELOUT Abderrahmane (2019)
Thèse de doctorat

Le travail présenté dans cette thèse porte sur l’élaboration et l’étude de films d’oxydes  métalliques d’oxyde de zinc (ZnO) non dopé et dopé à l’aluminium (AZO) et d’oxyde de cuivre  (Cu2O) dont les propriétés sont modulées par la variation de la pression partielle d’oxygène (PO2) dans l’intervalle [0,05 - 1,30 mbar] tout en maintenant la pression d'argon fixée à 0,05 mbar, en vue de leur application dans différents domaines. Les dépôts ont été réalisés en utilisant la technique de pulvérisation DC et le dépôt laser pulsé (Pulsed Laser Deposition) (PLD). Les différentes propriétés des échantillons ont été étudiées à travers des analyses de diffraction de rayons X (XRD), de spectroscopie Raman, de transmissions optiques (UV – vis), de microscopie électronique à balayage (MEB) et de mesures électriques d’effet Hall et de caractéristiques courant-tension (I-V) dans le cas des hétérojonctions. Tous les résultats révèlent l’influence particulière des différents intervalles de valeur de la pression d’oxygène, sur les films déposés de ZnO et de Cu2O. Un traitement thermique par un laser infrarouge de différentes énergies, effectué sur les couches de Cu2O a affecté considérablement leurs différentes propriétés. Des hétérojonctions Cu2O/AZO et Cu2O/ZnO/AZO ont été déposées sur des substrats de verre par dépôt de laser pulsé. Elles ont aussi été caractérisées par microscopie à force atomique (AFM) et par microscopie électronique à balayage (MEB). On montre que l’insertion d’une couche de ZnO entre Cu2O et Le film AZO dans l’hétérojonction augmente la taille moyenne des grains et améliore la rugosité de la surface supérieure de l’hétérojonction (surface de la couche AZO). Les mesures de courant-tension (I-V) révèlent que les hétérojonctions réalisées, présentent des comportements remarquables de diodes. La présence du film mince intermédiaire de ZnO réduit de manière significative les courants parasites et de fuite à travers la barrière, améliore la qualité de l’hétérostructure, modifie la bande d’énergie entre les couches AZO et Cu2O en la rendant moins abrupte (plus lisse) et contribue à diminuer la possibilité de la recombinaison des porteurs de charge à l'interface, augmentant ainsi leur durée de vie. L’activité photocatalytique des films ZnO et Cu2O a été étudiée au moyen d’essais sur la photodégradation de la rhodamine B (RhB) et du méthyl-orange (MO) sous irradiation directe de rayons solaires. Une étude comparative a été menée entre le ZnO et le Cu2O pour la décoloration de la Rhodamine B et du Methyl-orange sous la lumière solaire. Les résultats ont montré que les films de ZnO présentent une activité photocatalytique plus grande avec la rhodamine B que le méthyle orange, qui présente plutôt une photodégradation plus importante avec les films de catalyseur de Cu2O. Après exposition des films à la lumière solaire pendant 6 h, un taux d'élimination de 81,69% a été obtenu pour le méthylorange sur des films de Cu2O, tandis que pour la rhodamine B, le meilleur taux d'élimination (60,85%) a été obtenu avec le ZnO.La pression partielle d’oxygène, le traitement thermique au cours des dépôts sont des paramètres clé affectant les propriétés des films d’oxydes métalliques déposés, leur conférant une application appropriée. Voir les détails

Mots clés : oxydes transparentes conducteurs, pulvérisation cathodique, caractérisation électrique, dopage des semiconducteurs, caractérisation optique, caractérisation structurale.

Thermo-physico-chemical and statistical mechanical properties of Washingtonian filifera new lignocellulosic fiber. Engineering Solid Mechanics

Djamel Edinne Gaagaiaa, Mustapha Bouakba, Abdelheq Layachi  (2019)
Publication

In this work, novel cellulosic fibers are extracted from Washingtonia Filifera (WF) plant using an environment-friendly technique. Morphological, Physico-chemical, thermal and mechanical properties are reported in this paper. Micro graphical SEM shows the presence of cells in the fiber.FTIR and XRD experimental analyzes show a cristinality index of 48.88%, and the WF fibers are found to be thermally stable until 201°C by using TGA and DTG thermographic analyzes with an appropriate activation energy of 72.46 kJ/mol, where Young modulus and tensile strength of strain were determined using tensile tests of single fiber at 2.17 GPa, 134 MPa and 26.55%, respectively. Mechanical properties are analyzed using a statistical method. Voir les détails

Mots clés : WF fibers, mechanical properties, FTIR, XRD, TGA, Statistical methods

Study and development of a new process for the treatment and purification of industrial effluents contaminated by metals by electrodeposition

Souad brick chaouche, Ahmed HADDAD, AICHA BENSMAILI  (2019)
Article de conférence

Currently, Electrochemical methods find wide application in the treatment of industrial effluents to reduce their organic matter content, in inorganic sulfur compounds and nitrogen, or in harmful metals for the environment. Electrochemistry is not only applied to wastewater, but also on contaminated soils, incineration residues or sewage sludge wastewater from the metallurgical industry. Electrochemistry has proved its effectiveness, which allowed him to integrate the environmental industry. Environmental electrochemical technologies allow to control pollution, to recycle materials, to carry out the rehabilitation of sites, monitoring (monitors and sensors for gases and liquids), the efficient conversion of energy, the prevention of corrosion, removal of contaminants and disinfection of water. Electrochemical processes can therefore be efficient and economical when properly designed, and they integrate harmoniously with the environmental industry. These processes require compact installations and can thus integrate into existing industrial waste treatment chains. The present work aims so the elaboration of an electrochemical process of treatment and purification of industrial effluents contaminate with metals. Indeed, the use of this technique can allow both the elimination of these metals by electroplating on a cathode, a recovery of metals, a saving of precipitation reagents and a reduction in the amount of sludge to be removed, as well as surface treatments where the applications concern gold recovery, silver, copper, cadmium, nickel, zinc, iron and lead ... etc. The metal that can be recovered in the form of valorizable cathodes, which allows the depollution of the environment. This work requires in-depth studies of design considerations and the development of an electrolytic cell. Voir les détails

Mots clés : electrochemical, environment, pollution

PredictiveControl of a Grid Connected PVSystemsIncorporating Active Power FilterFunctionalities

N. Hamouda, B. Babes, S. Kahla, Y. Soufi, J. PETZOLDT, T. Ellinger  (2019)
Article de conférence

This paper presents a multifunction operation of adouble stage grid connected photovoltaic system, with insertionthe active power filter (APF) functionalities. This system is usedto compensate the reactive power, suppression harmonicscurrents supply the nonlinear loads and inject the active powerinto grid. Our work is focused on the grid side, a perturbationand observation control is used to reach the maximum powerpoint tracking (MPPT) regardless of solar radiation. On the gridside, a modified instantaneous active and reactive poweralgorithm (P-Q) based on a multi-variable filter (MVF) is usedin order to identify the harmonics currents reference underdistorted source voltage condition, also a modified predictivecurrent control (PCC) algorithm is used to control the sourcevoltage inverter in order to ensure compensate reactive powerand harmonic currents, feed the non linear load and inject thesurplus generated power into the grid. In Matlab/Simulinksoftware, the proposed control scheme is investigated under loadchange and radiation change conditions. Simulation resultsshows that the proposed PCC of the APF guarantees a flexiblesettlement of real power amounts exchanges with the grid with ahigh power factor operation. Furthermore, the grid currentrecovers its sinusoidal waveform with a total harmonic distortion(THD) meet to IEEE-519 standard Voir les détails

Mots clés : Photovoltaic system (PV), activ power filter (APF), Predictive current control (PCC), active and reactive power theory (P-Q), multivariable filter (MVF), total harmonic distortion (THD)

Analyses physico-chimique et rhéologique des boues d'épuration des eaux uséesde la ville de Guelma

CHIBANI Sana (2010)
Mémoire de magister

In general, the sludge must be of agronomic interest, for this it must be easier to use, it means that sludge can be easily stored, transported and spread easily. More than the knowledge of the dry matter content, viscosity and physico-chemical composition are necessary to process optimization of storage and application techniques. However, the variable quality of output sludge treatment plant makes the heterogeneous volumes involved in the context of agricultural development.This study aims mainly to identify the rheological and physico-chemical parameters ofsludge. The quality of wastewater, treated wastewater and sludge is often determined by a set of physicochemical parameters. Applied to the treatment plant of Guelma city, il showed significant heterogeneity over months. For protection against wastewater pollution, they must be treated before being discharged into the environment by biological techniques of activated sludge. The purified water can be used for various purposes (irrigation, industry, etc ....), especially for Guelma’s zone which is agricultural.Our work is involved in the study and the characterization of wastewater entering the treatment plant and water discharges after treatment of the city of Guelma and in addition of the study and the characterization of sludge during treatment. Physical and chemical indicators of pollution are determined i.e.: the BOD5, COD, TSS, VSS, TKN, OPO4--, NO2 -, NO3 -, K +, Cl-... and the temperature, pH, dissolved oxygen, conductivity. This study is carried out for two months.Our results suggest that wastewater is polluted by organic pollution characterized by partially degradable waste and sludge is rich organic matter and mineral. Rheological study also showed that sludge is linear viscous and elastic behaviour.Finally, the use of sewage sludge has enabled is the best method of treatment because of its large reduction in pollution load Voir les détails

Mots clés : Keywords: sewage disposal, water treatment, physicochemical indicator, activated sludge.

Conception of a friction stir welding tool

M. AISSANI, S. Gachi, D.H. BASSIR, F. Boubenider, Y. Benkedda  (2008)
Article de conférence

Friction stir welding is a new process that allows a solid-state joining technology of metallic components. Applications and development within this approach has incr eased during the last decade. In this process, the geometry of friction tool plays a fundamental role to obtain suitable microstructures in the weld and the heat affected zones, thus it will be then possible to improve the strength and fatigue resistance of the joint. Among the articles related to the friction process, only few have treated the manufacturing process of the tool. In this work, we will focus on this last point. To increase the welding quality and the process reliability, the design of the tool includes a shaft-spring-based system aimed at avoiding premature damage, furthermore to allow the measure of applied friction pressure. Our improved friction tool has then been tested for applied this welding technique on Al-2024 and Al-7075 aluminium alloys sheets. The weld quality has been evaluated by means of a microstructure analysis and micro-hardness measurements. The ability to increase the welding speed, the changes of the crystalline plans orientation in the mixed part of thermo-mechanically affected zone and grains sizes observed in micrographics underline the effect of the pin geometry and its displacement. The micro-hardness curve shows good mechanical properties. Finally, the obtained results show a su ccessful welding with accep table quality and open new interesting perspectives. Voir les détails

Mots clés : Aluminium, conception, Friction Stir Welding, tool, Micro-hardness