Boulesbaa M.,University of Ouargla
Spectroscopy Letters | Year: 2017
The effect of thermal annealing on the optical and physicochemical properties of hydrogenated silicon nitride films was studied. These films were deposited by plasma-enhanced chemical vapor deposition from a mixture of silane, ammonia, and nitrogen. Subsequently, the films were annealed at various temperatures ranging from 400°C to 1000°C. The properties of the films were studied using ellipsometry and Fourier transform infrared spectroscopy. The Maxwell Garnet model considers the silicon nitride material as heterogeneous with three distinct phases: silicon, stoichiometric silicon nitride, and hydrogen. Based on the ellipsometric analysis, the annealing treatment leads to reduce the volume fraction of both hydrogen and silicon. As a result, the stoichiometry parameter significantly increases from 1.24 to 1.32 making it closer to the stoichiometric silicon nitride one. According to the infrared data, a noticeable decrease in the total hydrogen concentration in the films was obtained with respect to the annealing temperature. © 2017 Taylor & Francis.
Touchan R.,University of Arizona |
Anchukaitis K.J.,Lamont Doherty Earth Observatory |
Meko D.M.,University of Arizona |
Attalah S.,University of Ouargla |
Aloui A.,Institute of Sylvo pastoral of Tabarka
Climate Dynamics | Year: 2011
Changes in precipitation patterns and the frequency and duration of drought are likely to be the feature of anthropogenic climate change that will have the most direct and most immediate consequences for human populations. The latest generation of state-of-the-art climate models project future widespread drying in the subtropics. Here, we reconstruct spatially-complete gridded Palmer drought severity index values back to A. D. 1179 over Morocco, Algeria, and Tunisia. The reconstructions provide long-term context for northwest African hydroclimatology, revealing large-scale regional droughts prior to the sixteenth century, as well as more heterogeneous patterns in sixteenth, eighteenth, and twentieth century. Over the most recent decades a shift toward dry conditions over the region is observed, which is consistent with general circulation model projections of greenhouse gas forced enhanced regional subtropical drought. © 2010 Springer-Verlag.
Benmir A.,University of Ouargla |
Aida M.S.,University of Mentouri Constantine
Energy Procedia | Year: 2013
This paper deals with the development of an analytical model for simulating a polycrystalline Cu(In,Ga)Se2(CIGS)-based thin film solar cells by a CdS(n)/CIGS(p) heterojunction structure. Consequently, a link between the characteristics of this cell and the material parameters is established. This procedure would help improving the performances of the cell. We have been investigating over this work the contribution of the space charge region in the photocurrent density which seemed to be dominant in comparison to the neutral regions. However, the increases of the buffer layer thickness only reduce the cell performances. The optimum thickness of the absorber layer was about 3 μm, a value from which the efficiency has no significant increase. The increase of the absorber bandgap reduces the optical absorption, which is reflected in the reduction of the photocurrent density. Accordingly the open circuit voltage increases as a result to the linear variation with the band gap. The compromise between these two phenomena would be a band gap of 1.55 eV which is the optimum value for obtaining a high efficiency of about 25%. All these optimization results give helpful indication for a feasible fabrication process. © 2010 Published by Elsevier Ltd.
Boulakroune M.,University of Ouargla
Applied Surface Science | Year: 2016
This paper deals the effectiveness and reliability of multiresolution deconvolution algorithm for recovery Secondary Ions Mass Spectrometry, SIMS, profiles altered by the measurement. This new algorithm is characterized as a regularized wavelet transform. It combines ideas from Tikhonov Miller regularization, wavelet analysis and deconvolution algorithms in order to benefit from the advantages of each. The SIMS profiles were obtained by analysis of two structures of boron in a silicon matrix using a Cameca-Ims6f instrument at oblique incidence. The first structure is large consisting of two distant wide boxes and the second one is thin structure containing ten delta-layers in which the deconvolution by zone was applied. It is shown that this new multiresolution algorithm gives best results. In particular, local application of the regularization parameter of blurred and estimated solutions at each resolution level provided to smoothed signals without creating artifacts related to noise content in the profile. This led to a significant improvement in the depth resolution and peaks’ maximums. © 2016 Elsevier B.V.
Meraoumia A.,University of Ouargla |
Chitroub S.,Signal Sciences |
Bouridane A.,Northumbria University
Integrated Computer-Aided Engineering | Year: 2013
Biometric systems based on a single source of information suffer from limitations such as the lack of uniqueness, non-universality of the chosen biometric trait, noisy data and spoof attacks. Multimodal biometrics are relatively new systems that overcome those problems. These systems fuse information from multiple sources in order to achieve the better person recognition performance. In this paper, the 2D and 3D information of palmprint are integrated in order to construct an efficient multimodal biometric system based on fusion at matching score level and at feature extraction level. The observation vectors are created independently either from the original data of the two modalities (2D and 3D palmprint) or from their rotation invariant variance measures applied on textures. On each modality (or its corresponding invariant texture), we have applied the Principal Component Analysis (PCA) for reducing dimension of the feature vector. We have also used the multi-scale wavelet decomposition for each modality and the results of decomposition are combined and compressed using PCA for selecting the feature vectors. Subsequently, we have used the Hidden Markov Model (HMM) for modeling the feature vectors. Finally, Log-likelihood scores are used for palmprint evaluation. We note that the selected principal components of two modalities are fused at feature level and at matching score level. The proposed scheme is tested and evaluated using PolyU 2D and 3D palmprint database of 250 persons. Our experimental results show the effectiveness and reliability of the proposed system, which brings high identification accuracy rate. © 2013 - IOS Press and the author(s). All rights reserved.
Aiboud S.,University of Ouargla |
Saouli S.,University of Ouargla
International Journal of Non-Linear Mechanics | Year: 2010
This paper presents the application of the second law analysis of thermodynamics to viscoelastic magnetohydrodynamic flow over a stretching surface. The velocity and temperature profiles are obtained analytically using the Kummer's functions and used to compute the entropy generation number. The effects of the magnetic parameter, the Prandtl number, the heat source/heat sink parameter and the surface temperature parameter on velocity and temperature profiles are presented. The influences of the same parameters, the Hartmann number, the dimensionless group parameter and the Reynolds number on the entropy generation are also discussed. © 2010 Elsevier Ltd. All rights reserved.
Gouamid M.,University of Ouargla |
Ouahrani M.R.,University of Ouargla |
Bensaci M.B.,University of Ouargla
Energy Procedia | Year: 2013
The ability of Date palm Leaves powder (DPLP) to remove methylene blue (MB) from aqueous solutions by the biosorption process has been studied. Biosorption studies were carried out at different initial dye concentration, contact time, initial solution pH, biosorbent dosage, the particle size of (DPLP) and temperature. Biosorption data were modeled using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich adsorption isotherms. The results showed that equilibrium was reached within 160 min. The used biosorbent gave the highest adsorption capacity at pH 6.5. Equilibrium data of the biosorption process fitted very well to the Temkin model (R2=0.994). The maximum adsorption capacity, Langmuir's qmax, improved from 43.103 to 58.14 mg/g as the temperature increased from 30 to 60°C. The enthalpy ΔH° and entropy ΔS° values were respectively estimated at 8.098 kJ mol -1 and 12.97 J K-1 mol-1 for the process. Three simplified kinetic models including a pseudo-first-order equation, pseudo-second-order equation and intraparticle diffusion equation were selected to follow the adsorption process. Kinetic parameters, rate constants, equilibrium sorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was shown that the adsorption of methylene blue (MB) could be described by the pseudo-second order equation (R2= 0.996), methylene blue is slowly transported via intraparticle diffusion into the particles and is finally retained in micropores, suggesting that the adsorption process is presumable a physisorption © 2013 The Authors.
Yasmina M.,University of Ouargla |
Mourad K.,University of Ouargla
Energy Procedia | Year: 2014
In order to optimize the purification of water and sewage water, a new technique of degradation "the heterogeneous photocatalysis" of the organic matter was underlined. As catalyst we chose a semiconductor which is dioxide TiO2 the titanium in the presence of a lamp UV as source of energy. One model substances present in many industrial effluents: the 4-iso propyl phenol was selected. The results of our experiments show that the adsorption of the pollutant (10-4mol/l) on TiO2 supported in absence of radiation UV is negligible. Compared to direct photolysis UV (365nm), the devolution of the pollutant is definitely faster in the presence of TiO2/UV for the same experimental conditions. © 2014 Published by Elsevier Ltd.
Said S.M.,University of Ouargla
Physics Procedia | Year: 2014
In this work, we will study an inverse problem to determine the corrosion in an inaccessible location of a metallic plate. Our study area is inside a metallic plate whose lower part is embedded, therefore inaccessible. We will perform measurements on the upper part of the plate, which is not in contact with the ground. For this, we will send an electric field on this part, and take measurements. This problem is modeled by a mixed Laplace problem with presence of an unknown term in the boundary conditions; this term is an unknown function which can take several forms. This function detects the presence or absence of corrosion inside the plate. For this, we make electrical measurements on different parts of the plate on different time intervals, this gives us information about detection and evolution of the corrosion on this part of the plate. We will first formulate our problem which is an inverse problem, and we will make a theoretical study. We will show that this problem has a unique solution, also this solution is stable. After, we will solve this problem by constructing an iterative algorithm which gives a series of cross problems which give the approximate values of impedance functions, which determine the rate of corrosion. Finally we study the convergence and make a numerical application. © 2014 Elsevier B.V.
Douak M.,University of Ouargla |
Settou N.,University of Ouargla
Energy Procedia | Year: 2015
In response to problems involved in the current crisis of petrol in Algeria, with the decrease in the price of the oil barrel, the rate of growth in domestic electricity demand and with an associated acceleration of global warming, as a result of significantly increased greenhouse gas (GHG) emissions, renewable energy seems today as a clean and strategic substitution for the next decades. However, the greatest obstacles which face electric energy comes from renewable energy systems are often referred to the intermittency of these sources as well as storage and transport problems, the need for their conversion into a versatile energy carrier in its use, storable, transportable and environmentally acceptable are required. Among all the candidates answering these criteria, hydrogen presents the best answer. In the present work, particular attention is paid to the production of hydrogen from wind energy. The new wind map of Algeria shows that the highest potential wind power was found in Adrar, Hassi-R'Mel and Tindouf regions. The data obtained from these locations have been analyzed using Weibull probability distribution function. The wind energy produced in these locations is exploited for hydrogen production through water electrolysis. The objective of this paper is to realize a technological platform allowing the evaluation of emergent technologies of hydrogen production from wind energy using four wind energy conversion systems of 600, 1250, 1500 and 2000 kW rated capacity. The feasibility study shows that using wind energy in the selected sites is a promising solution. It is shown that the turbine "De Wind D7" is sufficient to supply the electricity and hydrogen with a least cost and a height capacity factor. The minimum cost of hydrogen production of 1.214 $/kgH2 is obtained in Adrar. © 2015 The Authors. Published by Elsevier Ltd.