WorldCat Identities

Université Mouloud Mammeri (Tizi-Ouzou, Algérie) Faculté des sciences exactes

Overview
Works: 5 works in 8 publications in 1 language and 8 library holdings
Roles: Degree grantor, Other
Publication Timeline
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Most widely held works by Algérie) Université Mouloud Mammeri (Tizi-Ouzou
Etude théorique de la migration de lacunes et de l'oxygène interstitiel dans le nickel solide soumis à un processus d'oxydation by El Hocine Megchiche( Book )

2 editions published in 2007 in French and held by 2 WorldCat member libraries worldwide

This thesis is dedicated to the study of the dynamical properties of various systems of interacting random walkers. In the first part of this manuscript, we study a model of self-gravitating Brownian particles. In this model, the particles evolve at fixed temperature. This corresponds to a canonical description of self-gravitating systems. When the temperature is above a certain critical temperature, metastable equilibrium states exist. By contrast, below this critical temperature, the system collapses and forms a Dirac peak. It has been shown that the model of self-gravitating Brownian particles shares numerous analogies with the chemotaxis of biological populations. In this thesis, we generalize these results to the multi-component case, in which the particles can have different masses. In addition, we study the phase transitions between gaseous states and condensed states for a model of self-gravitating Brownian particles (or its biological analog) around a central body. Moreover, we show that the model of self-gravitating Brownian particles exhibits many analogies with the Bose-Einstein condensation of free bosons strongly coupled with a thermal bath. This model corresponds to a canonical description (fixed temperature) of the Bose-Einstein condensation. The coupling between a thermal bath and a system of free bosons induces a effective interaction between the bosons. This one forces them to condensate in their fundamental state when the temperature is less than a certain critical temperature. We then study the solutions of the bosonic Fokker-Planck equation of this problem which leads to the formation of a Dirac peak, modeling the condensate. In the second part of this thesis, we study the freely decaying two-dimensional turbulence. Two-dimensional turbulence has the striking property to generate a set of coherent structures called vortices. If the turbulent system evolves freely (without any external forcing), the turbulent fluid decays due to the merging processes of like-sign vortices. Some studies have shown that two-body merging processes are dominant for large vortex densities whereas there are inefficient at very low density: in this case, the evolution is dominated by three-body processes
Synthèse d'hydroxyapatite et de silices greffées pour l'élimination de métaux toxiques en solution aqueuse by Madjid Hadioui( Book )

2 editions published in 2007 in French and held by 2 WorldCat member libraries worldwide

Two convenient synthesis methods of heavy metals recovery materials have been described in this work. One relates to immobilization of polyamine ligands on silica gel surface in aqueous medium and the other on the synthesis of the hydroxyapatite under inexpensive conditions. Taking into account the regenerability of the synthesized products, the modification of the surface of silica gel led to satisfying grafting rates. Preparation of the calcium phosphate starting from calcium carbonate and ammonium phosphate at ambient temperature led to pure hydroxyapatite after calcination of the intermediate product and elimination of the CaO by washing with distilled water. The adsorption of Pb2+ ions on HA column led to the formation of lead phosphate microparticles. The rates of eliminated Pb2+ were relatively high and the studies at various flow rates showed that 1g of HA can recover up to 0.5 mg of Pb2+ in one minute. The sorption of Pb2+ on the HA was also studied in the presence of EDTA and glycine in solution. Microanalyse results showed that Pb2+ ions are fixed in greater amount at less than 10 µm of the edge of the HA grains, while Cu2+, Cd2+ and Zn2+ diffuse inside the grains
Extension de la modélisation par FDTD en nano-optique by Abderrahmane Belkhir( Book )

2 editions published in 2008 in French and held by 2 WorldCat member libraries worldwide

This thesis concerns works on electromagnetics modelisations in nano-optics application using Finite Difference Time Domain method (FDTD. Bidimentional FDTD codes for dielectric and metallic photonic band gaps have been implemented in the in-plane and off-plane cases. Another code, BOR-FDTD, has been implemented in order to simulate metallic materials with revolution symmetry. The perfectly matched layer (PML) is included in BOR-FDTD code. Finally, an FDTD-3D numerical code has been developed for simulating periodic lattice structures in oblique incidence. This code includes the PML absorption conditions, Drude and Drude-Lorentz models. Several important applications have been found and investigated using these codes
Synthèse d'hydroxyapatite et de silices greffées pour l'élimination de métaux toxiques en solution aqueuse by Madjid Hadioui( )

1 edition published in 2008 in French and held by 1 WorldCat member library worldwide

Dans ce travail nous décrivons deux méthodes pratiques de synthèse de matériaux fixateurs d'ions de métaux lourds. L'une porte sur le greffage en milieu aqueux du gel de silice par des polyamines (TETA, TEPA et PEHA) et l'autre sur la synthèse de l'hydroxyapatite dans des conditions peu coûteuses. La modification de la surface du gel de silice a conduit à des taux de greffage satisfaisants compte tenu de la régénérabilité des produits synthétisés. La préparation du phosphate de calcium à partir du carbonate de calcium et du phosphate d'ammonium à température ambiante a conduit à de l'hydroxyapatite pure après calcination du produit intermédiaire et élimination du CaO par lavage à l'eau distillée. L'adsorption d'ions Pb2+ sur colonne d'HA donne lieu à la formation de microparticules de phosphate de plomb de plus de 0,45 µm de taille. Les taux de Pb2+ éliminés sur colonne d'HA sont relativement élevés et les études de percolation à différents débits ont montré que 1 g d'HA peut fixer jusqu'à 0,5 mg de Pb2+ en une minute. La fixation de Pb2+ sur l'HA a également été étudiée en présence d'EDTA et de glycine en solution. Grâce à des analyses à la microsonde électronique, nous avons constaté que les ions Pb2+ se fixent en plus grande quantité à moins de 10 µm du bord des grains d'HA, tandis que les ions Cu2+, Cd2+ et Zn2+ diffusent à l'intérieur des grains
Etude théorique de la migration de lacunes et de l'oxygène interstitiel dans le nickel solide soumis à un processus d'oxydation by El Hocine Megchiche( )

1 edition published in 2008 in French and held by 1 WorldCat member library worldwide

This thesis is dedicated to the study of the dynamical properties of various systems of interacting random walkers. In the first part of this manuscript, we study a model of self-gravitating Brownian particles. In this model, the particles evolve at fixed temperature. This corresponds to a canonical description of self-gravitating systems. When the temperature is above a certain critical temperature, metastable equilibrium states exist. By contrast, below this critical temperature, the system collapses and forms a Dirac peak. It has been shown that the model of self-gravitating Brownian particles shares numerous analogies with the chemotaxis of biological populations. In this thesis, we generalize these results to the multi-component case, in which the particles can have different masses. In addition, we study the phase transitions between gaseous states and condensed states for a model of self-gravitating Brownian particles (or its biological analog) around a central body. Moreover, we show that the model of self-gravitating Brownian particles exhibits many analogies with the Bose-Einstein condensation of free bosons strongly coupled with a thermal bath. This model corresponds to a canonical description (fixed temperature) of the Bose-Einstein condensation. The coupling between a thermal bath and a system of free bosons induces a effective interaction between the bosons. This one forces them to condensate in their fundamental state when the temperature is less than a certain critical temperature. We then study the solutions of the bosonic Fokker-Planck equation of this problem which leads to the formation of a Dirac peak, modeling the condensate. In the second part of this thesis, we study the freely decaying two-dimensional turbulence. Two-dimensional turbulence has the striking property to generate a set of coherent structures called vortices. If the turbulent system evolves freely (without any external forcing), the turbulent fluid decays due to the merging processes of like-sign vortices. Some studies have shown that two-body merging processes are dominant for large vortex densities whereas there are inefficient at very low density: in this case, the evolution is dominated by three-body processes
 
Audience Level
0
Audience Level
1
  General Special  
Audience level: 0.93 (from 0.92 for Etude thé ... to 0.95 for Etude thé ...)

Languages
French (8)