Publications Scientifiques

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Author: search.filters.author.Hachemi, Madjid

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    An experimental study of the pattern formation in forced surface waves
    (Springer, 2022) Guedifa, Reda; Hachemi, Madjid
    Pattern formation in forced surface waves occurs between two layers of immiscible fluids of different densities, in which a vertical vibration is imposed, leading to stationary waves. This experimental study focuses primarily on the formation of the various wave patterns (solitary waves and meniscus waves) and the onset of Faraday waves. Three control parameters are varied to produce different flow patterns: the forcing amplitude and frequency as well as the depth (Af, ωf, Γ ). In this paper, we investigate low forcing frequencies ranging from 3 to 5 Hz, and high forcing amplitudes ranging from 3 to 15 mm. The measured responses correspond to the oscillation frequencies of the free surface ωs and their associated wavelength λs. It is found that a succession of equilibrium states occurs spatially periodic structures and symmetric up to well-defined thresholds. Beyond these thresholds, symmetrical structures are broken and may follow two different paths: chaos follows the onset of the cross of Saint Andrew (meniscus wave) occupying all of the diagonal or an unstable pattern in the form of an odd polygon.
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    Catalytic effects of eggshell ash on the conversion of used engine oil to fuel by pyrolysis
    (Taylor and Francis, 2022) Zerdane, Youghourta; Largeau, Jean François; Hachemi, Madjid; Tazerout, Mohand
    The objective of this work is to recycle used engine oil until it is converted into an alterna- tive fuel by catalytic pyrolysis. The effect of using eggshell ash as a catalyst in pyrolysis reac- tions on the yield of the resulting fractions was investigated. In addition, the influence of this catalyst on the compositions and the quality of the non-condensable gas and liquid fractions were analyzed. The results show that the liquid fraction recovered 97.02%wt; with 20%wt of the catalyst is predominant. The detection of aromatics 15.84%wt, olefins 32.74%wt, naphthenic 2.82%wt, paraffins 29.00%wt, and alcohols 20.50%wt, in the pyrolytic liquid and the observation of H2 15.22%wt, CH4 16.65%wt and other elements such as C4H8 21.93%wt in non-condensable gases, make it possible to predict the good usability of these products obtained as an alternative fuel.
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    Axisymmetric frictionless contact between an elastic layer thickness and a circular base under a rigid punch
    (SAGE, 2023) Guerrache, Fadila; Boutoutaou, Hamid; Hachemi, Madjid
    The study presented in this work deals with analytical methods for an axisymmetric problem of an elastic layer partially reposing on a rigid circular base, and is indented along the upper surface with a rigid punch. The contact between the medium and the base is smooth. This boundary value problem is transformed into a system of dual integral equations. In contrast to the classical approach consisting in resolving the corresponding Fredholm equation of the second kind, the latter equations are obtained from an infinite algebraic system of simultaneous equations, where the particular case (Formula presented.) is verified. The results of this system are also obtained numerically. The normal displacement, normal stress, and the stress singularity factor are given analytically and shown graphically with discussion. By comparison with those predicted by the finite element method, the accuracy of the numerical method is approved
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    Experimental investigation on petroleum sludge valorization into fuel via pyrolysis process
    (Springer Science and Business Media B.V., 2017) Bellahcene, Amal; Hachemi, Madjid; Largeau, Jean-François; Tarabet, Lyes; Burnens, Gaëtan; Khiari, Karim; Tazerout, Mohand
    Oil sludge (OS) has been of key concern due to its continuing effect on the environment degradation. The huge quantities thrown yearly of this waste contain a high proportion of hydrocarbons which are valuable for recovery. This study focused on the oil sludge conversion into a fuel for a diesel engine by thermal/catalytic pyrolysis process. The experiments were conducted at atmospheric pressure in a batch reactor operated without and with two catalyst types: TiO2 (3 and 5 wt%) and Al2O3(3 and 5 wt%). Overall all test conditions followed in the OS pyrolysis, a considerable liquid fraction is recovered (around 70%), as compared to the gaseous fraction (around 25%) and the solid residue (around 5%). The characterization of the pyrolytic oil samples, containing approximately 11.70% of oxygen, showed also that the use of 5% of Al2O3 catalyst in the OS cracking provide the best fuel quality with a minimum viscosity value (3.5 mm2/s), a maximum heating value (45.72 MJ/kg) with a hydrocarbon compounds in the range (C7–C32) which are detailed by GC–MS analysis. The others properties (density, flash point, pour point and cloud point) are found to be close to those of diesel fuel. Also, the catalysts effect is studied on the others pyrolysis products. The obtained results allow to predict the good usability as a diesel like fuel. Further tests to control engine performance and pollutant emissions could be done Graphic Abstract
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    Effect of Carreau-Yasuda rheological parameters on subcritical Lapwood convection in horizontal porous cavity saturated by shear-thinning fluid
    (AIP, 2017) Khechiba, Khaled; Mamou, Mahmoud; Hachemi, Madjid; Delenda, Nassim; Rebhi, Redha