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Search Results: 1 - 10 of 3379 matches for " Fayard Claude "
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Exotic atoms in two dimensions
Combescure Monique,Fayard Claude,Khare Avinash,Richard Jean-Marc
Physics , 2010,
Abstract: We study the behavior of energy levels in two dimensions for exotic atoms, i.e., when a long-range attractive potential is supplemented by a short-range interaction, and compare the results with these of the one- and three-dimensional cases. The energy shifts are well reproduced by a scattering length formula $ \delta{E}= A_0^2/\ln (a/R)$, where $a$ is the scattering length in the short-range potential, $A_0^2/(2\,\pi)$ the square of the wave function at the origin in the external potential, and $R$ is related to the derivative with respect to the energy of the solution that is regular at large distances.
Production de soie et caractéristiques des glandes séricigènes de 13 races de ver à soie (Bombyx mori)
JM Fayard
Genetics Selection Evolution , 1978, DOI: 10.1186/1297-9686-10-2-259
Abstract:
Réduction de l'oxyde d'azote par la suie dans les produits de combustion Reduction of Nitric Oxyde by Soot in Combustion Products
De Soete G.,Fayard J.
Oil & Gas Science and Technology , 2006, DOI: 10.2516/ogst:1978044
Abstract: On a étudié dans un réacteur à lit fixe la réduction du NO par de la suie formée dans des flammes riches de mélanges éthane/oxygène/argon. Le mélange gazeux traversant le réacteur est de l'argon dopé avec du NO; dans certains cas ce mélange est enrichi d'hydrogène ou d'oxyde de carbone. En présence d'hydrogène ou d'oxyde de carbone, ces vitesses sont nettement plus grandes qu'avec la suie seule. La comparaison avec des vitesses réactionnelles obtenues sur des lits fixes composés d'autres matériaux solides, tels que l'alumine, montre que la réduction de l'oxyde d'azote se fait principalement par une réaction hétérogène avec l'hydrogène et l'oxyde de carbone catalysée par la suie. D'autres matériaux solides,tels que des oxydes réfractaires présentent une activité catalylique aussi importante que la suie. Cette observation fournit une nouvelle explication de l'effet connu de certains additifs sur la réduction de NO dans les flammes. Dans la seconde partie de l'étude, on mesure la réduction des oxydes d'azote dans les flammes fuligineuses de prémélange. De l'argon dopé par de l'oxyde d'azote est injecté dans les produits de combustion de ces flammes chargés de suie; l'introduction du NO est faite à différentes distances derrière le br leur, correspondant à différents niveaux de température des produits de combustion. La réduction fractionnelle des oxydes d'azote est mesurée en fonction de la concentration en suie, en hydrogène et en oxyde de carbone, en faisant varier la composition du mélange inflammable. Les résultats expérimentaux sont en bon accord avec la réduction calculée en se basant sur les informations cinétiques obtenues en lit fixe. The kinetics of nitric oxide réduction by soot collected from hydrocarbon flames is studied in a fixed-bed reactor. The gas flow traversing thé reactor is either argon with NO, or argon with hydrogen and NO, or argon with carbon monoxide and NO. In thé présence of either CO or H2, thé réduction rate of nitric oxide is several orders of magnitude higher than with soot clone. Comparison with réaction rates obtained with nonreducing bed packings, such as alumina, proves that thé réduction of NO is substantially produced by a heterogeneous réaction, with hydrogen or carbon monoxide acting as thé reducing agent. The rote played by soot is principally that of a cotalyst. Other solid particles (such as oxides) may produce such a réduction of NO with a catalytic efficiency as great as or even greater than that of soot. This conclusion casts new light on thé rote ployed by some flame additives in thé réduction of nitric oxide
Mécanisme de l'usure par polissage des cylindres de moteurs diesel Bore Polishing Wear Mechanism in Diesel Engine Cylinders
Ayel J.,Tahon G.,Fayard J. C.
Oil & Gas Science and Technology , 2006, DOI: 10.2516/ogst:1982026
Abstract: Une méthode rapide et économique d'évaluation des lubrifiants et des combustibles vis-à-vis de l'usure par polissage des cylindres de moteurs diesel suralimentés a été mise au point sur moteur monocylindre de laboratoire dans le cadre d'une convention de recherche Société Nationale Elf Aquitaine - Institut Fran ais du Pétrole (SNEA-IFP). Cette méthode référencée IFP-UP-4/80, permet également de juger de la tendance à la formation de dép ts et au gommage, de l'usure des segments et de la tendance à la consommation d'huile des lubrifiants. Elle est en bonne corrélation avec l'essai CEC-Ford Tornado et discrimine très bien les huiles de référence RL 47 et RL 48 du Conseil Européen de Coordination (CEC). Elle a permis l'étude du mécanisme de l'usure par polissage en recherchant l'influence de paramètres essentiels : - Constitution du lubrifiant : le phénomène est influencé par la nature de l'huile de base et par sa viscosité, par la quantité de polymères améliorant l'indice de viscosité et surtout par le choix des additifs détergents. En première approximation et pour des familles d'huiles homogènes, l'usure par polissage augmente lorsque la stabilité thermique de l'huile diminue. - Fonctionnement du moteur : le polissage cro t très vite avec la charge du moteur à partir d'un certain seuil, son évolution en fonction du temps, observée par cotation endoscopique, présente une allure caractéristique en S, le polissage commence du c té poussée et en haut du cylindre. - Constitution du combustible : l'augmentation de la teneur en soufre du gazole diminue fortement l'usure par polissage provoquée par une huile réputée mauvaise sur ce plan mais est sans effet sur une bonne huile. - Etat de surface du cylindre : le prépolissage de la chemise par pierrage extrêmement fin ne conduit pas aux mêmes phénomènes que ceux observés lorsque la chemise est polie in situ dans le moteur en fonctionnement. En particulier, l'usure des segments ainsi que les débits de gaz de soufflage, sont plus faibles qu'avec une chemise normale. Enfin, le mécanisme de l'usure par polissage par abrasion douce à deux et à trois corps est parfaitement confirmé par une exploration micrographique et une microanalyse des surfaces polies. A fast and economical method for evaluating lubricants and fuels in relation to the bore polishing wear of super charged diesel-engine cylinders has been developed using a single-cylinder laboratory engine within the framework of an Société Nationale Elf Aquitaine - Institut Fran ais du Pétrole (SNEA-lFP) research agreement. This method bears the reference IFP-UP-4/80
One blind and three targeted searches for (sub)millisecond pulsars
E. Davoust,G. Petit,T. Fayard
Physics , 2011, DOI: 10.1051/0004-6361/201117384
Abstract: We conducted one blind and three targeted searches for millisecond and submillisecond pulsars. The blind search was conducted within 3deg of the Galactic plane and at longitudes between 20 and 110deg. It takes 22073 pointings to cover this region, and 5487 different positions in the sky. The first targeted search was aimed at Galactic globular clusters, the second one at 24 bright polarized and pointlike radiosources with steep spectra, and the third at 65 faint polarized and pointlike radiosources. The observations were conducted at the large radiotelescope of Nancay Observatory, at a frequency near 1400 MHz. Two successive backends were used, first a VLBI S2 system, second a digital acquisition board and a PC with large storage capacity sampling the signal at 50 Mb/s on one bit, over a 24-MHz band and in one polarization. The bandwidth of acquisition of the second backend was later increased to 48 MHz and the sampling rate to 100 Mb/s. The survey used the three successive setups, with respective sensitivities of 3.5, 2.2, and 1.7 mJy. The targeted-search data were obtained with the third setup and reduced with a method based on the Hough transform, yielding a sensitivity of 0.9 mJy. The processing of the data was done in slightly differed time by soft-correlation in all cases. No new short-period millisecond pulsars were discovered in the different searches. To better understand the null result of the blind survey, we estimate the probability of detecting one or more short-period pulsars among a given Galactic population of synthetic pulsars with our setup: 25% for the actual incomplete survey and 79% if we had completed the whole survey with a uniform nominal sensitivity of 1.7 mJy. The alternative of surveying a smaller, presumably more densely populated, region with a higher sensitivity would have a low return and would be impractical at a transit instrument. (abridged)
Generating Net Forces from Backgrounds of Randomly Created Waves  [PDF]
Claude Gauthier
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.516158
Abstract: We examine the possibility of generating net forces on concave isolated objects from backgrounds consisting of randomly created waves carrying momentum. This issue is examined first for waves at the surface of a liquid, and second for quantum vacuum electromagnetic waves, both in relation with a one-side-open rectangular structure whose interior embodies a large number of parallel reflecting plates. Using known results about the Casimir-like effect and the original Casimir effect for parallel plates, we explain why and how such rectangular hollow structures should feel net oriented forces. We briefly describe real systems that would allow testing these theoretical results.
Wave-Particle Duality in Einstein-de Broglie Programs  [PDF]
Claude Elbaz
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.518213
Abstract: The standard model of particle physics forms a consistent system for universe description. After following quantum mechanics, it derives particles from relativistic quantum fields. Since it does not include gravitation, it describes only one aspect of the universe. In extension of general relativity, Einstein had proposed a symmetrical and complementary approach of physics. In his program, he privileged a relativist field based on representations for physical phenomena, before a precise mathematical description. It allows completing and unifying the universe description, like both eyes for relief vision, and both ears for stereophonic audition. We propose to show it with many simple examples.
Gravitation and Electromagnetism Conciliated Following Einstein’s Program  [PDF]
Claude Elbaz
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.65072
Abstract: The Einstein’s program permits to conciliate gravitation and electromagnetism. Besides the standard model, it forms a consistent system for universe description, founded upon a scalar field propagating at the speed of light c. Matter corresponds to standing waves. Adiabatic variations of frequencies lead to electromagnetic interaction constituted by progressive waves. Classical domain corresponds to geometrical optics approximation, when frequencies are infinitely high, and then hidden. As interactions for matter, Gravitation and Electromagnetism derive from variations of its energy E = mc2. Electromagnetic interaction energy derives from mass variation dE = c2dm, and gravitation from speed of light variation dE = mdc2. Contrarily to gravitation, only electromagnetic interaction serves as a bridge between classical and quantum frames, since it leans directly upon the wave property of matter: its energy dE = hdν = c2dm derives from variations of matter energy E = hν = mc2.
Book Review on Wilsonian Armenia: Stories behind the Failed Project by Rouben Ambartzumian  [PDF]
Claude Mutafian
Open Journal of Social Sciences (JSS) , 2017, DOI: 10.4236/jss.2017.52015
Abstract: The present book deals with a topic which has often been mentioned by various specialists of the Armenian question, but, as far as I know, never been studied per se. Rouben Ambartzumian [below quoted as RA] has decided to dig the question in order to understand and explain why the pro-Armenian projects of US president Woodrow Wilson turned to a total failure. Himself a brilliant world-famous mathematician, RA explores the field scientifically, as thoroughly as possible, in order to find, or eventually to guess, the reasons of the behaviour of the different actors of this tragedy.
Three-Body approach to the K^- d Scattering Length in Particle Basis
A. Bahaoui,C. Fayard,T. Mizutani,B. Saghai
Physics , 2002, DOI: 10.1103/PhysRevC.66.057001
Abstract: We report on the first calculation of the scattering length A_{K^-d} based on a relativistic three-body approach where the two-body input amplitudes coupled to the Kbar N channels have been obtained with the chiral SU(3) constraint, but with isospin symmetry breaking effects taken into account. Results are compared with a recent calculation applying a similar set of two-body amplitudes,based on the fixed center approximation, considered as a good approximation for a loosely bound target, and for which we find significant deviations from the exact three-body results. Effects of the hyperon-nucleon interaction, and deuteron $D$-wave component are also evaluated.
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