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OALib Journal期刊

ISSN: 2333-9721

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Numerical Study of Heat Transfer and Contaminant Transport in an Unsaturated Porous Soil  [PDF]
Abdelhamid Belghit, Mustapha Benyaich
Journal of Water Resource and Protection (JWARP) , 2014, DOI: 10.4236/jwarp.2014.613113
Abstract: Penetration of chemicals in the soil ground through irrigation water or rainfall induces important risks for the environment. These risks are badly known and may lead to direct contamination of the environment (atmosphere or ground water) or harmful effects on organisms living at ground level, indirectly affecting men. It is thus necessary to estimate these potential chemical risks on the environment. For that reason, the gradual change of these products (fertilizers, solutions, pollutants, ...) in the ground has been the subject of a lot of recent research works, based in particular on the study of non-saturated porous media in a theoretical, numerical or experimental way. Most of these works are incomplete and, in order to simplify the problem, they don’t take into accounts some process, which may be of prime importance under particular natural conditions. Complexity of such studies results from their multidisciplinary nature. In this communication, we study simultaneous transport of pollutant, the water that provides transport and the heat transfer in a 200 cm long cylindrical column full of sand taken as a non-saturated porous medium. We consider two kinds of conditions on the temperature at the column surface: the case of constant temperature and the case of sinusoidal temperature. We evaluate the influence of this temperature on the transfers. This study is purely numerical. We use the control volume method to determine hydrous, thermal and pollutant concentration profiles.
Biomass Char Steam Gasification in Fluidized Reactor Using Nuclear Heat  [PDF]
Abdelhamid BELGHIT
Open Access Library Journal (OALib Journal) , 2020, DOI: 10.4236/oalib.1106155
Abstract: The energy resources diversification has been increased with the energy crisis, in particular, the renewable energies and optimal management have become essential in the context of sustainable development. The conventional auto-thermal gasification processes burn part of the carbonaceous compound in order to supply the energy necessary to enhance gasification reactions. This energy could be provided as well by a nuclear reactor of IV generation. The nuclear heat is transferred from the VHTR to a He stream, which is mixed with the steam before entering the reactor. The syngas produced in this process has a high quality which is applicable for Fischer-Tropsch processor for power generation in fuel cells. The present work aims to develop a model for char steam gasification in a fluidized bed, with nuclear heat as the source of energy for the gasification reactions. The results of the model are compared with the data reported in the literature.
Existence of Weak Solution for a Free Boundary Lubrication Problem
Abdelhamid Laouar
ISRN Mathematical Analysis , 2011, DOI: 10.5402/2011/460602
Abstract:
Homogenization of a double porosity model in deformable media
Abdelhamid Ainouz
Electronic Journal of Differential Equations , 2013,
Abstract: The article addresses the homogenization of a family of micro-models for the flow of a slightly compressible fluid in a poroelastic matrix containing periodically distributed poroelastic inclusions, with low permeabilities and with imperfect contact on the interface. The micro-models are based on Biot's system for consolidation processes in each phase, with interfacial barrier formulation. Using the two-scale convergence technique, it is shown that the derived system is a general model of that proposed by Aifantis, plus an extra memory term.
Noradrenaline and Parkinson's Disease
Abdelhamid Benazzouz
Frontiers in Systems Neuroscience , 2011, DOI: 10.3389/fnsys.2011.00031
Abstract: Parkinson’s disease (PD) is characterized by the degeneration of dopamine (DA) neurons in the substantia nigra pars compacta, and motor symptoms including bradykinesia, rigidity, and tremor at rest. These symptoms are exhibited when striatal dopamine concentration has decreased by around 70%. In addition to motor deficits, PD is also characterized by the non-motor symptoms. However, depletion of DA alone in animal models has failed to simultaneously elicit both the motor and non-motor deficits of PD, possibly because the disease is a multi-system disorder that features a profound loss in other neurotransmitter systems. There is growing evidence that additional loss of noradrenaline (NA) neurons of the locus coeruleus, the principal source of NA in the brain, could be involved in the clinical expression of motor as well as in non-motor deficits. In the present review, we analyze the latest evidence for the implication of NA in the pathophysiology of PD obtained from animal models of parkinsonism and from parkinsonian patients. Recent studies have shown that NA depletion alone, or combined with DA depletion, results in motor as well as in non-motor dysfunctions. In addition, by using selective agonists and antagonists of noradrenaline alpha receptors we, and others, have shown that α2 receptors are implicated in the control of motor activity and that α2 receptor antagonists can improve PD motor symptoms as well as L-Dopa-induced dyskinesia. In this review we argue that the loss of NA neurons in PD has an impact on all PD symptoms and that the addition of NAergic agents to dopaminergic medication could be beneficial in the treatment of the disease.
Two-Scale limit of the solution to a Robin Problem in Perforated Media
Abdelhamid Ainouz
Mathematics , 2006,
Abstract: The two scale convergence of the solution to a Robin's type-like problem of a stationary diffusion problem in a periodically perforated domain is investigated. It is shown that the Robin's problem converges to a problem associated to a new operator which is the sum of a standard homogenized operator plus an extra first order "strange" term; its appearance is due to the non-symmetry of the diffusion matrix and to the non rescaled resistivity.
Derivation of a Convection Process in a Steady Diffusion-Transfer Problem by Homogenization
Abdelhamid Ainouz
Mathematics , 2007,
Abstract: We study the homogenization of a steady diffusion equation in a highly heterogeneous medium made of two subregions separated by a periodic barrier through which the flow is proportional to the jump of the temperature by a layer conductance of the same order of magnitude of the materials in consideration. The macroscopic governing equations and the effective conductivity of the homogenized model are obtained by means of the two scale convergence technique. We show that under some hypothesis the homogenized systems contain convective terms of order one.
Equilibrium states for smooth maps
Abdelhamid Amroun
Mathematics , 2010,
Abstract: We prove an equidistribution result for $C^{\infty}$ maps with respect to equilibrium states. We apply the result to the time-one map of the geodesic flow of a closed smooth Riemannian manifold.
Equidistribution results for geodesic flows
Abdelhamid Amroun
Mathematics , 2010, DOI: 10.1017/etds.2012.153
Abstract: Using the works of Ma\~n\'e \cite{Ma} and Paternain \cite{Pat} we study the distribution of geodesic arcs with respect to equilibrium states of the geodesic flow on a closed manifold, equipped with a $\mathcal{C}^{\infty}$ Riemannian metric. We prove large deviations lower and upper bounds and a contraction principle for the geodesic flow in the space of probability measures of the unit tangent bundle. We deduce a way of approximating equilibrium states for continuous potentials.
The Hua operators on homogeneous line bundle on Bounded Symmetric Domains of Tube Type
Abdelhamid Boussejra
Mathematics , 2011,
Abstract: Let D be a bounded symmetric domain of tube type . We show that the image of the Poisson transform on the degenerate principal series representation attached to the Shilov boundary of D is characterized by a covariant differential operator on a homogeneous line bundle on D.
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