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Numerical investigation of Reynolds number and scaling effects in microchannels flows

Journal of Hydrodynamics 2017年第4期29卷 647-658页

作者： s.A.si salah E.G.Filali s.djellouli Faculty of Mechanical and Process Engineering Houari Boumedienne University

Compared with conventional channels, experiments of microchannel often exhibit some controversial findings and sometimes even opposite trends, most notably the effects of the Reynolds number and the scaled channel height on the Poiseuille number. The experimental method has still been constrained by two key facts, firstly the current ability to machine microstructures and secondly the limitation of measurement of parameters related to the Poiseuille number. As a consequence, numerical method was adopted in this study in order to analyze a flow in two-dimensional rectangular microchannels using water as working fluid. Results are obtained by the solution of the steady laminar incompressible Navier-stokes equations using control volume finite element method（CVFEM） without pressure correction. The computation was made for channel height ranging from 50 ？m to 4.58 ？m and Reynolds number varying from 0.4 to 1 600. The effect of Reynolds number and channel heights on flow characteristics was investigated. The results showed that the Poiseuille numbers agree fairly well with the experimental measurements proving that there is no scale effect at small channel height. This scaling effect has been confirmed by two additional simulations being carried out at channel heights of 2.5 ？m and 0.5 ？m, respectively and the range of Reynolds number was extended from 0.01 up to 1 600. This study confirm that the conventional analysis approach can be employed with confidence for predicting flow behavior in microchannels when coupled with carefully matched entrance and boundary conditions in the dimensional range considered here.

关键词： Rectangular microchannel Poiseuille number control volume finite element method(CVFEM) laminar flow minichannels

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Characterization of organic matter deposited in the oriental zone from Moknine hypersaline environment, oriental Tunisia

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Chinese Journal Of Geochemistry 2005年第4期24卷 345-351页

作者： Raja CHAIRI Zohra EL AsMI djellouli Laboratoire de Ressources Minerales et Environnement Faculté des sciences de Tunis 2092 Univ. Tunis El Manar Tunisie Laboratoire de Ressources Minerales et Environnement Faculté des Sciences de Tunis 2092 Univ. Tunis El Manar Tunisie

The geochemistry data show that the total organic carbon (TOC) contents are high in the surface sediments in the eastern part of the Moknine’s sebkha. Low decreasing of organic matter (OM) with increasing depth indicates the good preservation of OM in modern sediments. “Lignite levels” inserted in the sand sequence and deposited at the edge and in the intermediate zone are considered as lithologic and organic markers. It is characterized by high TOC and poor hydrogen index (HI), indicating a higher plant origin and good preservation of OM in thin beds under anoxic condition.; In all samples low values of HI are typical for strong terrigenous input in the sebkha. Gas chromatography (GC) of saturate fraction showed that OM in the border zone is provided from plants but in the central zone OM is a mixture of terrestrial fraction and little fraction from microalgae. The study of free lipids indicated that this environment was influenced by intense bacterial and microbial activities, as evidenced by the abundance of n-alkanes and nC-{18}-nC-{22}.

关键词：突尼斯地球化学有机物质褐煤地质条件

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FullApertureReconstruction of theAcoustic Far-Field Pattern from Few Measurements

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Communications in Computational Physics 2012年第2期11卷 647-659页

作者： Helene Barucq Chokri Bekkey Rabia djellouli INRIA Bordeaux sud-Ouest Research Center Team Project Magique-3D&LMA/CNRS UMR 5142Universite de Pau et des Pays de l’AdourFrance Faculte des sciences de Monastir Tunisia Department of Mathematics California State University Northridge&Interdisciplinary Research Institute for the SciencesIRISUSA

We propose a numerical procedure to extend to full aperture the acoustic farfield pattern(FFP)when measured in only few observation *** reconstruction procedure is a multi-step technique that combines a total variation regularized iterative method with the standard Tikhonov regularized *** proposed approach distinguishes itself from existing solution methodologies by using an exact representation of the total variation which is crucial for the stability and robustness of Newton *** present numerical results in the case of two-dimensional acoustic scattering problems to illustrate the potential of the proposed procedure for reconstructing the full aperture of the FFP from very few noisy data such as backscattering synthetic measurements.

关键词： Acoustic scattering problem limited aperture inverse obstacle problem ill-posed problem total variation Tikhonov regularization Newton method

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A Modified Discontinuous GalerkinMethod for solving Efficiently Helmholtz Problems

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Communications in Computational Physics 2012年第2期11卷 335-350页

作者： Magdalena Grigoroscuta-strugaru Mohamed Amara Henri Calandra Rabia djellouli INRIA Bordeaux sud-Ouest Research Center Team Project Magique-3D and LMA/CNRS UMR 5142Universit´e de Pau et des Pays de l’AdourFrance BCAM Basque Center for Applied MathematicsBilbaoSpain. TOTAL Avenue LarribauPauFrance Department of Mathematics California State University Northridge and Interdisciplinary Research Institute for the SciencesIRISUSA

A new solution methodology is proposed for solving efficiently Helmholtz *** proposed method falls in the category of the discontinuous Galerkin ***,unlike the existing solution methodologies,this method requires solving(a)well-posed local problems to determine the primal variable,and(b)a global positive semi-definite Hermitian system to evaluate the Lagrange multiplier needed to restore the continuity across the element *** numerical results obtained for two-dimensional interior Helmholtz problems are presented to assess the accuracy and the stability of the proposed solution methodology.

关键词： Helmholtz equation discontinuous Galerkin plane waves Lagrange multipliers inf-sup condition waveguide problems

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Role of Periodic Input Composition and sweeping Gas for Improvement of Hydrogen Production in a Palladium Membrane Reactor by Partial Oxidation of Methane

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Chinese Journal of Chemical Engineering 2012年第3期20卷 577-588页

作者： Lemnouer Chibane Brahim djellouli Laboratoire de Génie des Procédés Chimiques(LGPC) UniversitéFerhat AbbasSétif19000 Algérie

The partial oxidation of methane under periodic operation over Ni/y/-Al2O3 catalyst was investigated in a Pd-membrane reactor. The effects of key parameters such as the inlet composition and the sweeping, gas on methane conversion and the hydrogen recovery are numerically estalallshed with two penodtc input ttmctlons. In order to analyze the effect of the inputs modulation, the reaction was performed under low steam to methane ratio at a mod-erate temperature and pressure. It was obtained that to achieve process intensification is to operate the process in a periodic way. The main results show that the periodic input functions can improve the performance of the process compared to the optimal steady state operation. Moreover, there is an optimum amplitude of manipulated inputs leads to a maximum of hydrogen recovery. It is noteworthy that the comparison between the predicted performancevia the sinusoidal and the＇square ways show that the better＇average performance was obtainedwith the square way.

关键词： hydrogen production modulation periodic operation Pd-membrane reactor

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Bioequivalence of Two Brands of Metformin 850 mg Coated Tablets in 12 Healthy Algerian Volunteers： A Pilot study

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Journal of Pharmacy and Pharmacology 2017年第10期5卷 736-741页

作者： Mansouri, K. Aissa, L. Bounab, A. H., Hadjaz I. M. Nekhoul, K. djellouli, s. Kheddouci, L. Cherait, I. Behloul, s. Mansouri, M. B. Department of Bioequivalence National Control Laboratory for Pharmaceuticals Products Algiers 16000 Algeria

A randomized, two-way, crossover study was conducted in 12 fasting, healthy, algerian volunteers to compare the bioavailability of two brands of metformin hydrochloride 850 mg coated tablets. The present study aimed to appreciate the bioequivalence of the generic product and to evaluate the intra-subject variability of this active substance in the Algerian population. The test brand was compared to Glucophage （Merck UK） as the reference product. The study was performed at the bioequivalence center of the national control laboratory for pharmaceuticals products from 03 to 04, 2011, in joint venture with specialized medical hospital center of E1 Hadi Flici, Algiers, Algeria. The drug was administered with 200 mL of water after a 10 h overnight fasting on two treatment days separated by one week washout period. After dosing, serial blood samples were collected for a period of 12 h. A reliable, simple, and robust liquid chromatography-tandem mass spectro-metric （LC-Ms/Ms） method has been developed and validated for estimation of metformin in human plasma using propranolol as internal standard. The analytes were extracted from plasma by using the protein precipitation extraction technique. The assay was found to be linear over the range of 50-3000 ng/mL with a lower limit of quantitation of 50 ng/mL. Various pharmacokinetic parameters including AUC0-t, AUC0-∞, Cmax, Tmax, and T1/2 were determined from plasma concentrations of both formulations and found to be in good agreement with reported values. The pharmacokinetical and statistical analysis was conducted with Kinetica 4.4.1. AUC0-t, AUC0-∞ and Cmax were tested for bioequivalence after log-transformation of data. No significant difference was found based on ANOVA; 90% confidence interval （[91.62 %, 115.66%] for AUC0-t, [92.07 %, 115.53 %] for AUC0-∞; [94.58%, 119.58 %] for Cmax） of test/reference ratio for these parameters were found within bioequivalence acceptance range of 80-125%. Based on these statistical inferen

关键词： Metformin hydrochloride bioequivalence LC-Ms/Ms pharmacokinetics

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