Liste des documents
Trace and essential elements determination in baby formulas milkby INAA and k0-INAA techniques
As a part of the food analysis program executedat Es-Salam research reactor by neutron activation analysislaboratory, the concentration of As, Ba, Br, Ca, Fe, K, La,Rb and Zn in baby formulas milk have been determined byusing INAA and k0-NAA techniques. It was found that theconcentration of all elements obtained by both techniqueswas relatively identical for the three brands of the 0–6 and6–12 months of analyzed samples. In addition, the analyticalresults have been compared with those given byproducers. Voir les détails
Mots clés : Trace and essential elements, NAA method, Milk products, Analysis
A comparative Study of Two Types of DTC With Application of Artificial Intelligence: Fuzzy Logic and Neuron Network on the Performance of a Multi-level Inverter Fed Induction Machine
We present in this paper the simulation results of the speed control of a 3 levels inverter-fed induction machine controlled by the Direct Torque Control with application of artificial intelligence techniques both the fuzzy logic(DTC_FL) and the neural network (DTC_NN). A comparative study of these two techniques is also presented to illustrate the merits of each of the techniques on the performance of the 3-levels inverter-/induction machine set. Voir les détails
Mots clés : Induction machine, 3-Levels Inverter, Direct Torque Control (DTC), DTC_FL, DTC_NN
A COMPARATIVE STUDY OF TWO TYPES OF DTC WITH APPLICATION OFARTIFICIAL INTELLIGENCE: FUZZY LOGIC AND NEURON NETWORK ON THEPERFORMANCE OF A MULTI-LEVEL INVERTER FED INDUCTION MACHINE
We present in this paper the simulation results of the speed control of a 3 levels inverter-fed induction machine controlled by the Direct Torque Control with an application of artificial intelligence techniques both the fuzzy logic(DTC_FL) and the neural network (DTC_NN). A comparative study of these two techniques is also presented to illustrate the merits of each of the techniques on the performance of the 3-levels inverter-/induction machine set. Voir les détails
Mots clés : Induction machine, 3-Levels Inverter, Direct Torque Control (DTC), DTC_FL, DTC_NN
Automatic detection of articulations disorders from children’s speech preliminary study
Automatic detection of articulations disorders from children’s speech preliminary study Voir les détails
Mots clés : GMM-UBM SVM Model fusion Articulations disorders Speech disorders
Analysis of the Electromagnetic Interferences betweenOverhead Power Lines and Buried Pipelines
The Analysis of electromagnetic interference between high voltage overhead power transmission lines and nearby gas/oil pipeline has been a topic of growing interest for many years. When pipelines are located in shared row with power lines, the pipeline can incur high induced voltages and currents due the AC interference. The induced voltage on pipeline can be dangerous for operator to touch the pipeline as well as pipe corrosion can result from AC discharge. This research evaluates and analyzes the electromagnetic interference effects on oil and gas buried pipelines created by the nearby high voltage transmission lines. The aim is to evaluate the AC corrosion likelihoods of pipelines and suggest proper mitigation solutions. Voir les détails
Mots clés : AC interference, Induced Voltages, Electric Power Transmission Lines, pipeline, AC Corrosion, Corrosion protection.
Deposition of tin(II) sulfide thin films by ultrasonic spraypyrolysis: Evidence of sulfur exo-diffusion
Tin Sulfide (SnS) thin films were deposited by ultrasonic spray pyrolysis technique, on glass substrate heated at 280 °C, with different deposition times. The used precursor SnCl2 and thiourea are dissolved in methanol. X-ray diffraction (XRD) analysis indicates that films are mainly composed with orthorhombic SnS phase at low deposition time. With increasing deposition time, the hexagonal SnS2 phases become dominant. SnO2 and metallic Sn phases have been detected with increasing deposition time. Scanning electron microscopy (SEM) observations reveal that films surfaces are rough with the presence of bubbles due to S2 gas exo-diffusion from the bulk during film growth. A model of S gas formation is presented. Voir les détails
Mots clés : Tin Sulfide Thin films Spray pyrolysis
Discoloration of Azo Dye Solutions by Adsorption on Activated Carbon Prepared from the Cryogenic Grinding of Used Tires
This present work reports a study about the adsorption of cationic dye (Methylene blue) by activated carbon prepared from the cryogenic grinding of used tires. Characterization of the obtained activated carbon by chemical analysis, FTIR and SEM, was studied and resumed that the activated carbon was mesoporous. The effect of various experimental parameters such as contact time, solution pH, adsorbent dose and dye concentration, on the dye adsorption uptake on the activated carbon has been investigated using batch adsorption experiments. According to the experiments results, it was shown, that equilibrium was achieved in less than 114 min. The effect of pH investigated for values ranging from 2 to 11, showed maximum adsorption for pH 11. The equilibrium adsorption isotherms models of Langmuir, Freundlich and Dubinin-Radushkevich, were tested for the quantitative description of the dye adsorption. The Langmuir isotherm provided the best fit for dye adsorption onto the prepared activated carbon and the maximum adsorption capacity was found to be 30.21 mg.g-1. The results show that the produced activated carbon from used tire is an alternative low-cost adsorbent for removing dyes from solutions. Voir les détails
Mots clés : adsorption, FTIR, SEM
Effect of Biobased Plasticizers on Thermal, Mechanical, andPermanence Properties of Poly(vinyl chloride)
Phthalates can be replaced by other harmless andenvironmentally friendly plasticizers, such as isosorbidediesters (ISB), and epoxidized sunflower oil (ESO),which has been proved an efficient stabilizer for poly(vinyl chloride) (PVC) in helping to prevent degradationduring processing. Formulations based on PVC withdifferent amounts of ISB, ESO, and di-(2-ethylhexyl)phthalate (DEHP) from 0 to 60 parts by weight per hundredparts of resin were realized. To make PVC flexiblewith partial amounts of the debated phthalates asplasticizers, we use a combination of DEHP, ISB, andESO. Effects of these two biobased plasticizers, ISBand ESO, and their mixture with DEHP on thermal stabilityby measuring discoloration degrees and thermalgravimetric analysis, on mechanical properties suchtensile strength, elongation at break, and hardness,were characterized. Plasticizer permanence propertiesof PVC compounds were studied. Studies showed thatprocessibility and flexibility were improved by the additionof a plasticizer system (ISB, ESO, and DEHP). Anincrease in the content of ISB and/or ESO increasedthermal and mechanical properties, whereas compositionswith ternary compositions of ISB/ESO/DEHP (15/15/30) exhibited the best performance properties. Voir les détails
Mots clés : PVC, Sunflower oil, Leaching, Volatility
Physical and photo-electrochemical characterizations of ZnO thin films deposited by ultrasonic spray method: Application to HCrO4−photoreduction
ZnO thin films, prepared by ultrasonic spray onto glass substrate, crystallize in the wurtzite structure. The XRD pattern shows preferential orientation along the [0 0 2] direction. The films deposited at 350 consist of 60 nm crystallites with an average thickness of ∼150 nm and SEM images show rough surface areas. The gap increases with increasing the temperature of the substrate and a value of 3.25 eV obtained for films deposited at 350?C. ZnO is nominally non-stochiometric and exhibits n-type conduction because of the native defects such as oxygen vacancies (VO) and/or interstitial zinc atom (Zni) which act as donor shallows. The conductivity is thermally activated and obeys to an exponential type law with activation energy of 57 meV and an electron mobility of 7 cm2V−1s−1. The capacitance-voltage (C−2measurement in acid electrolyte (pH ∼ 3) shows a linear behavior with a positive slope, characteristic N-type conduction. A flat band potential of −0.70 VSCE and a donors density of 5.30 × 1016cm−3are deter-mined. The Nyquist plot exhibits two semicircles attributed to a capacitive behavior with a low density of surface states within the gap region. The centre is localized below the real axis with a depletion angle of 16?ascribed to a constant phase element (CPE) due to the roughness of the film. The energy band diagram assesses the potentiality of ZnO films for the photo-electrochemical conversion. As application, 94% of chromate (3.8 × 10−4M) is reduced after 6 h under sunlight (AM 1) with a quantum yield of 0.06%and the oxidation follows a first order kinetic. Voir les détails
Mots clés : ZnO, thin film, Ultrasonic spray, Photo-electrochemical, Chromate, Sunlight
Étude du comportement thermique et mécanique des matériaux aéronautiques par des méthodes numériques: application au soudage de structure métallique
L’assemblage par soudage des constructions et des structures métalliques à usage aéronautique, tend vers l’utilisation intense de procédés de soudage modernisés tels que le soudage par l’arc électrique TIG et par friction malaxage FSW. Pour réduire le poids des appareils et des structures métalliques, il est envisagé dans les recherches actuelles de remplacer le rivetage par le soudage. Dans le présent travail, l’intérêt sera porté sur l’étude de ces deux procédés. Dans un premier temps, une étude du comportement thermique induit par le procédé de soudage TIG est menée. L’effet thermique important produit par la fusion des parties à assembler, crée dans la structure des zones à risques. Une modélisation et une simulation numérique adéquate du transfert thermique sont réalisées mettant en évidence l’effet des différents paramètres de soudage. Une étude expérimentale permettant une comparaison et une validation des résultats est ensuite présentée. Les résultats expérimentaux trouvés sont en bon accord avec les résultats numériques obtenus. Aussi, une étude du comportement mécanique des tôles soudées par le procédé TIG est faite sur la base d’essais de traction réalisés sur des éprouvettes normalisées ; elle a permis de s’initier à l’étude du comportement du matériau analysé. Dans un second temps, une étude de conception et de réalisation d’un nouvel outil de soudage par friction malaxage FSW est effectuée (Brevet [Aissani 2007]). Des essais de soudage ont été menés par la suite avec succès ; les joints de soudure réalisés ont été examinés et contrôlés par des tests CND (Contrôle Non Destructif). Enfin, une caractérisation mécanique et métallographique des cordons de soudure obtenus, par ces procédés, nous a permis de déterminer les propriétés mécaniques des soudures et la comparaison selon ces procédés. Voir les détails
Mots clés : soudage TIG, soudage FSW, ZAT, ZF, cycle thermique, champ thermique, acier 304L, alliage d’Aluminium