Dynamical Evolution of the Extra Dimension in Brane Cosmology

The evolution of the extra dimension is investigated in the context of brane world cosmology. New cosmological solutions are found. In particular, solutions in the form of waves travelling along the extra dimension are identified.Comment: Latex file, 10 page

Solutions of Higher Dimensional Gauss-Bonnet FRW Cosmology

We examine the effect on cosmological evolution of adding a Gauss-Bonnet term to the standard Einstein-Hilbert action for a (1 + 3)+ d dimensional Friedman-Robertson-Walker (FRW) metric. By assuming that the additional dimensions compactify as a power law as the usual 3 spatial dimensions expand, we solve the resulting dynamical equations and find that the solution may be of either de Sitter or Kasner form depending upon whether the Gauss-Bonnet term or the Einstein term dominates.Comment: 10 pages, references added/corrected, accepted for publication in General Relativity and Gravitatio

Virial mass in DGP brane cosmology

We study the virial mass discrepancy in the context of a DPG brane-world scenario and show that such a framework can offer viable explanations to account for the mass discrepancy problem. This is done by defining a geometrical mass $\mathcal{N}$ that we prove to be proportional to the virial mass. Estimating $\mathcal{N}$ using observational data, we show that it behaves linearly with $r$ and has a value of the order of $M_{200}$, pointing to a possible resolution of the virial mass discrepancy. We also obtain the radial velocity dispersion of galaxy clusters and show that it is compatible with the radial velocity dispersion profile of such clusters. This velocity dispersion profile can be used to differentiate various models predicting the virial mass.Comment: 12 pages, 1 figure, to appear in CQ

Cosmic Censorship and the Dilaton

We investigate extremal electrically charged black holes in Einstein-Maxwell-dilaton theory with a cosmological constant inspired by string theory. These solutions are not static, and a timelike singularity eventually appears which is not surrounded by an event horizon. This suggests that cosmic censorship may be violated in this theory.Comment: 16 pages, NSF-ITP-93-9

LA DISPONIBILITE ET LES CONCEPTS F.M.D EN MAINTENANCE INDUSTRIELLE

Le concept maintenance, considéré encore comme une fatalité éprouvée par les gestionnaires, est une approche ou plus une adéquation d’un ensemble d’activités visant à maintenir à un degré convenable les moyens de production à un prix optimum pour satisfaire la disponibilité et la sécurité des équipements. La maintenance s’impose impérativement dans la fonction de la gestion de la production même et exige des décisions pour que ses objectifs, préalablement définis, soient atteints. La maintenance est l’ensemble des opérations (dépannage, graissage, visite, réparation, amélioration, ...) qui permettent de conserver le potentiel du matériel donc en état de stabilité pour assurer la continuité du matériel et la qualité de la production dans les conditions de sécurité. Bien maintenir, c’est assurer ces opérations au coût global optimum. La tendancescientifique que les technologues sont contraints de pratiquer pour maintenir à un degré appréciable et avancé la disponibilité quasi permanente des équipements industriels de production à des prix toniques s’oriente vers le défi zéro panne et zéro stock de pièces de rechange. The concept of maintenance seen as inevitableeven by experienced managers,is more an approach or match a set of activities designed to maintain a proper degree the means of production to an optimal price to meet the availability and security equipment. Maintenance absolutely bound in the function of managing the production itself and requires decisions to ensure its objectives, previously defined, are met. Maintenance is the set of operations (repairs, lubrication,visit, repair, improvement ...)that keep the potential of the material thus in a state of stability to ensure continuity and quality of material production in safely. Well maintained, ensuring that these operations to the overall cost optimum.The scientific tendency that technologists are forced to practice to maintain a substantial degree and short-term availability of advanced industrial equipment production at prices tonic moves to challenge zero breakdowns and zero stock of spare parts

Quantum Theory of Black Holes

A solvable 2-dimensional conformally invariant midi-superspace model for black holes is obtained by imposing spherical symmetry in 4-dimensional conformally invariant Einstein gravity. The Wheeler-DeWitt equation for the theory is solved exactly to obtain the unique quantum wave functional for an isolated black hole with fixed mass. By suitably relaxing the boundary conditions, a non-perturbative ansatz is obtained for the wave functional of a black hole interacting with its surroundings.Comment: Plain-TeX, 13 pages, no figures, WIN-92-9, UNB Tech. Rep. 92-0

Étude de préfaisabilité du turbinage des eaux de la station de traitement de Koudiet Acerdoune/Algérie

This study aims to recover the residual energy of the water in the water treatment plant using turbines instead of wasting energy in the dissipator as it is currently done by means of load- breaker valves. Analysis of the technical efficiency of the project and an assessment of the hydroelectric potential available were carried out and different options for the installation of turbines were proposed. The estimated maximum amount of energy that can be recovered is around 7.44 GWh, and the maximum amount of carbon emissions saved are 446.210 tons. The evaluation of the profitability of our project integrating an energy recovery device is fair.Cette étude vise à récupérer l'énergie résiduelle de l’eau à son arrivée dans la station de traitement d'eau par turbinage, au lieu de continuer à la dissiper comme on le fait actuellement au moyen de robinets brises-charge. Une analyse de la faisabilité technique du projet et une évaluation du potentiel hydroélectrique disponible ont été accomplies, avant de proposer différentes options pour l’installation des équipements de turbinage. En utilisant cette méthode, le maximum de quantité d'énergie qui peut être récupérée a été estimée à 7,44 GWh, celui de la quantité de carbone économisée a été estimé à 446,210 tonnes CO2. Nous concluons notre projet par une évaluation de la rentabilité des aménagements hydroélectriques

Location Optimization of a Hydraulic Turbine for Koudiet Acerdoune Water Treatment Plants

This study aims to recover the residual energy of the water in the water treatment plant using turbines instead of wasting energy in the dissipator as it is currently done by means of load- breaker valves. Analysis of the technical efficiency of the project and an assessment of the hydroelectric potential available were carried out and different options for the installation of turbines were proposed. The estimated maximum amount of energy that can be recovered is around 7.44 GWh, and the maximum amount of carbon emissions saved are 446.210 tons. The evaluation of the profitability of our project integrating an energy recovery device is fair

Étude de préfaisabilité du turbinage des eaux de la station de traitement de Koudiet Acerdoune/Algérie

This study aims to recover the residual energy of the water in the water treatment plant using turbines instead of wasting energy in the dissipator as it is currently done by means of load- breaker valves. Analysis of the technical efficiency of the project and an assessment of the hydroelectric potential available were carried out and different options for the installation of turbines were proposed. The estimated maximum amount of energy that can be recovered is around 7.44 GWh, and the maximum amount of carbon emissions saved are 446.210 tons. The evaluation of the profitability of our project integrating an energy recovery device is fair.Cette étude vise à récupérer l'énergie résiduelle de l’eau à son arrivée dans la station de traitement d'eau par turbinage, au lieu de continuer à la dissiper comme on le fait actuellement au moyen de robinets brises-charge. Une analyse de la faisabilité technique du projet et une évaluation du potentiel hydroélectrique disponible ont été accomplies, avant de proposer différentes options pour l’installation des équipements de turbinage. En utilisant cette méthode, le maximum de quantité d'énergie qui peut être récupérée a été estimée à 7,44 GWh, celui de la quantité de carbone économisée a été estimé à 446,210 tonnes CO2. Nous concluons notre projet par une évaluation de la rentabilité des aménagements hydroélectriques