Liste des documents
Elaboration and Characterization of Copper Oxide (CuO) Thin Films Deposited bythe Spray Pyrolysis Method
In this work, a copper oxide thin films were deposed by a simple and inexpensive technique (spraypyrolysis) on ordinary glass substrates at a fixed temperature T=500°C. and differentconcentration of precursor 15, 30 and 45 ml made with H2O like solvent.The structural, morphological and optical properties of thin films of CuO were studied by X-raydiffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectrophotometry. The Xray diffraction patterns confirm the presence of the polycrystalline phase of CuO as monocliniccrystal structure with preferential orientation along (110), (002), (111) and (020). Their opticalband gaps ranged from 3.95 to 4.02eV with a high absorbency in the visible region. Voir les détails
Mots clés : Copper oxide, Thin films, Spray pyrolysis, Band Gaps, XRD, SEM
A Copper Oxide (CuO) Thin Films Deposited by Spray Pyrolysis Method
A simple and low-cost procedure (spray pyrolysis) was used to elaborate copper oxide thin films on ordinary glass substrates. A copper nitrate was used and dissolved in two different solutions (Water, Methanol) S1 and S2 respectively in order to obtain an equal concentration;CS1, S2= 0.5M.The spray pyrolysis deposition made at fixed temperature T= 500°C and different volumes of S1 or S2 on the glass substrates. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectrophotometry were used to determinate the structural, morphological and optical properties of CuO thin films. The X-ray diffraction patterns confirm the presence of the polycrystalline phase of CuO as monoclinic crystal structure with preferential orientation along (110), (002), (111), (200) and (020). Their optical band gaps ranged from 3.95 to 4.02eV for thin films made with S1, and from 1.6 to 1.95eV for thin films made with S2 with a high absorbency in the visible region, which is in agreement with the values of the literature. Voir les détails
Mots clés : Copper oxide, Thin films, Spray pyrolysis, Band Gaps, XRD, SEM.
Propriétés Optique de TiO2 et Application de la Méthode de Swanepoel pour la Détermination de l’Épaisseur Optique et de l’Indice de Réfraction
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.
Effect of Zinc/Cadmium Proportion in the Properties of CdS LayersDeposited by Chemical Bath Depostion Method
Cadmium poisoning and the cost of panel recovery which is very expensive and difficult in the buffer layersof CdS in solar cell, for these two drawbacks, we do a search on the effect of proportion of zinc/cadmium inthe properties layers of CdS. For this, our studies study the properties of CdxZn1-xS layers deposited bychemical bath (CBD). CdZnS thin films were synthesized by chemical bath deposition (CBD) with differentdeposition protocols to optimize deposition parameters such as temperature, deposition time, ionconcentrations and pH. The surface morphology, structural, optical and chemical properties of the CdZnS thinfilms were studied by SEM, XRD, Raman and UV-visible spectrophotometer. The transmittance is 80% inthe visible region 300 nm - 800 nm; the crystalline structure is hexagonal for x ≥ 0.5 and cubic for x≤0.5, thegrain size is between 85.7 and 100 nm. It is observe that the transmittance and the shape change with theconcentration of zinc in the solution; this result favours the application of these films in solar cells application. Voir les détails
Mots clés : CdZnS, chemical bath, SEM, Raman, solar cells, thin films.
Melt Surface Temperature Monitoring In Tiltable Induction Furnace
The supervision of the induction furnace is the subject of increasing development because of the rising demand on reliability and safety. An essential aspect of the pyrometers of induction furnace is the determination of the exact temperature on the melt surface related to the current and frequency flow resulting from optimum coil position depending on the applied actual power. With the aid of the mathematical model that describes the appearance and development of the temperature change in the area of inductive cold wall crucible melting, with the use of the automatic control methods it is possible to determine the change of temperature variation corresponding to direct visualization of a meniscus forms on the melt surface under the energy created by the induction coil, the latter can fully or partly influence the meniscus. To solve the problem of pyrometer temperature variation we propose the determination and the study of the total interaction force related to the operating current of the induction generator. This contribution presents an application for melt temperature change detection through a case study of the tiltable induction furnace with induction generator MFG-20. The study indicates that the pyrometer of the measurement temperature is powerful device related to the development of a new control method. Voir les détails
Mots clés : Tiltable induction Furnace, cold wall crucible melting, pyrometer measurements, Infrared thermography measurement.
A Simple Isoparametric Finite Element Based on the Reddy’s Theory for the Laminated Plates Bending Analysis
The aim of this work is to develop a quadrilateral finite element based on Reddy’s third order shear deformation theory for the bending behavior analysis of composite laminated plates. The element is a C0 four-nodded isoparametric with seven degrees of freedom at each node, three translation components, two rotations and two higher order rotational degrees. In particular, selective numerical integration is introduced in order to improve the results and to alleviate the locking phenomenon. The performance and reliability of the proposed formulation are demonstrated by comparing the author’s results with those obtained using the three-dimensional elasticity theory, analytical solutions and other advanced finite element models. Voir les détails
Mots clés : Ajout mot cléThird Order Shear Deformation Theory, Ajout mot cléLaminated Composite Plates, Ajout mot cléFinite Element, Bending Behavior
DEVELOPMENT AND CHARACTERIZATION OF HYDROXYAPATITE FOR BONE USE
The objective of this work is the elaboration of a biomaterial Hydroxyapatite (Ca10 (PO4)6 (OH)2), by a synthetic method of precipitation, (CaCl2, 2H2O) as source of calcium and (Na2HPO4, 12 H2O) as a source of phosphate. After preparation, the powder was calcined at 900 °C for 90 minutes at a speed of 10 °C / min and compacted into pellets 12 mm in diameter and 2 mm thick. Sintered powder at different temperatures (1000 °C, 1100 °C, 1200 °C, and 1300 °C). In order to study the effect of sintering temperature on the microstructure, the physical and morphological properties of the elaborated hydroxyapatite, the density, the porosity, X-ray diffraction (DRX) and the scanning electron microscopy (SEM) were used for the characterization of the powder. The density decreases with the increase of the porosity, in fact the sample densifies easily when the porosity is lower Voir les détails
Mots clés : hydroxyapatite, SEM, DRX, Porosity, Density
AN EXPERIMENTAL STUDY ON MECHANICAL OF A COMPOSITE MATERIAL FOR ORTHOPEDIC USE
This study consists in the mechanical characterization of a composite material used in the fabrication of orthopedic prostheses by ONAAPH (Annaba- Algeria). The studied composite is the result of a combination of a polymethyl methacrylate (PMMA) resin, fiberglass reinforcements and an absorbent of the resin, namely Perlon. The method adopted for obtaining specimens is the same as that used in the manufacture of prostheses. except that the shape of the mold used in our study is rectangular, allowing to obtain composite plates. The three-point bending tests were carried out on a MTS43 universal machine in the Advanced Materials Research Unit (URMA / CRTI, Annaba/Algeria). The identification of the damage mechanisms according to the mechanical loading conditions as well as the degradation of the constitutive elements, will be discussed. Voir les détails
Mots clés : composite, mechanical tests, mechanical behavior, Finite Elements
Modeling and simulation of In0.15 Ga0.85 N/GaN strainquantum well structure for solar cells application
Quantum well solar cells based on III-V nitride semiconductor materials are a great technological interest by means to their physical and optical properties. In this study the effect of quantum well number on the characteristics (J-V), (P-V) and efficiency for the structure GaN/In 0.15 Ga0.85 N/ GaN was studied. our result showed that, the increase in the number of wells is accompanied by the increase of the light current density and the efficiency, for example with 50 wells we found Jight = 14(mA /cm2) and a efficiency 28%. Voir les détails
Mots clés : Quantum well, solar cell, GaN, InGaN
Analysis and Simulation in Electrical Networks Using SSSC Device for Damping Power Oscillations
A large power system has many interconnections and bulk power transmissions over long distance. As a result, there low frequency inter-zone oscillations which make the system vulnerable to cascade failures. Many different methods have been proposed to alleviate the oscillations in the power system. For many years, Power System Stabilizer (PSS) has been one of the devices traditionally used to dampen oscillations. It is reported that during some operating conditions, PSS may not effectively attenuate oscillations; for this reason, other effective alternatives are required in addition to PSSs. On the other hand, the advent of FACTS has led to a new and more versatile approach to controlling the power system in a desired way. These devices based on very advanced power electronics components (GTO, IGBT,…). FACTS devices according to their network connection are distinguished countervailing series, shunt and hybrid such as: SSSC, ASVC and IPFC, respectively. One of the best-innovated Flexible AC Transmission System devices is the Static Synchronous Series Compensator. The purpose of this paper is to study the control functions provided by the SSSC in controlling the power flow of the load capacity of power lines. Voir les détails
Mots clés : PSS, FACTS, GTO, IGBT, SSSC, ASVC, IPFC