Philippe JEAN-PIERRE

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/1999
• Auteurs : Jean-Pierre HermierAlberto BramatiA. Z. KhouryElisabeth GiacobinoJean-Philippe PoizatTiejun ChangPhilippe Grangier
• Organismes : Laboratoire Kastler Brossel Laboratoire Kastler Brossel Laboratoire Kastler Brossel Laboratoire Kastler Brossel Laboratoire Charles Fabry de l'Institut d'Optique / Optique quantique Laboratoire Charles Fabry de l'Institut d'Optique / Optique quantique Laboratoire Charles Fabry de l'Institut d'Optique / Optique quantique
• Publié dans Journal of the Optical Society of America. A Optics, Image Science, and Vision le 30/10/2020

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Résumé : The transverse distribution of intensity noise in the far field of semiconductor lasers has been experimentally studied. For a single-mode edge-emitting laser, it has been found that a large amount of noise is present in higher-order nonlasing transverse modes parallel to the diode junction. In the case of a spatially multimode vertical-cavity surface-emitting laser, each mode exhibits a large noise, but these noises show strong anticorrelations.

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Fichiers liés : 00558800.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/1999
• Auteurs : Philippe DelayeAlain BlouinDenis DroletJean-Pierre MonchalinLouis-Anne de MontmorillonGérald Roosen
• Organismes : Laboratoire Charles Fabry de l'Institut d'Optique / Manolia Industrial Materials Institute (NRCC) Industrial Materials Institute (NRCC) Industrial Materials Institute (NRCC) Laboratoire Charles Fabry de l'Institut d'Optique / Manolia Laboratoire Charles Fabry de l'Institut d'Optique / Manolia
• Publié dans Applied Physics Letters le 01/11/2020

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Résumé : We describe both theoretically and experimentally a polarization independent interferometric adaptive photodetector based on photorefractive two-wave mixing. The configuration is based on the simultaneous recording of two independent gratings in a single photorefractive crystal. Applied to the detection of ultrasonic signals, this interferometric photodetector operates with depolarized beams issued from multimode fibers and gives a detection limit close to the ultimate.

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Fichiers liés : PhD1-33.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/1999
• Auteurs : Jean PhilippePierre-Yves Léo
• Organismes : Centre d'Études et de Recherche en Gestion d'Aix-Marseille
• Publié dans Canadian Journal of Regional Science / Revue canadienne des sciences régionales le 23/10/2020

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/1999
• Auteurs : Philippe Jean-PierreChristophe HurlinGuillaume Gaulier
• Organismes : Centre d'Économie et de Management de l'Océan Indien Université de La Réunion Université d'Orléans Laboratoire d'Économie d'Orleans [FRE2014] Centre de recherche de la Banque de France
• Publié dans Annales d'Economie et de Statistique le 30/10/2020

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/1999
• Auteurs : L. JouniauxJean-Pierre PozziJean BerthierPhilippe Massé
• Organismes : Géophysique expérimentale (IPGS) Laboratoire de géologie de l'ENS Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
• Publié dans Journal of Geophysical Research : Solid Earth le 27/10/2020

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Résumé : Detection of changes in the flow rate of expelled fluids in accretionary prisms by monitoring of electric and magnetic fields is discussed. A numerical model of the electric and magnetic fields associated with fluid flow variations at the Nankai Trough is presented which gives a numerical solution of the coupled system of electric convection currents and conduction currents that directly determines the magnetic anomaly itself. Measurements in a borehole located between two vents are shown to be well adapted to detection of fluid flow variations using the vertical gradient of the electric potential and the horizontal magnetic field. The vertical electric field is about 10 mV/km up to 500 m depth where there is a lithologic reflector and about 50 mV/km below this reflector. The horizontal gradient of the magnetic field is 2 nT/km at the seafloor. Modelization with a lower fault conductivity and a larger décollement thickness has also been modeled. The vertical gradient of the horizontal magnetic field is ~5 to 15 nT/km. A variation of 3 mV and 1.5 to 3 nT at 600 m depth in a borehole could reveal a fluid flow rate variation of 20%, which is a reasonable fluid flow change based on some observations at short-scale time. Since a 1.5 to 3 nT anomaly seems easier to detect than a 3 mV anomaly, it is likely that the variation of the magnetic field would more sensitively reveal fluid flow variations. When monitoring the magnetic field at the seafloor, a change of 0.4 nT/km in the horizontal gradient could reveal a fluid flow rate variation of 20%.

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Fichiers liés : 1999JB900102.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/1999
• Auteurs : Jean-Philippe BoulangerChristophe Menkes
• Organismes : Laboratoire d'océanographie dynamique et de climatologie Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques
• Publié dans Climate Dynamics le 30/10/2020

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Résumé : The TOPEX/POSEIDON sea level data have been shown to observe the sea surface height variability accurately over the globe and, more particularly, in the tropical Pacific, core region of the El Niño/Southern Oscillation. Various studies have already provided descriptions of long equatorial wave propagation as well as estimates of their reflection at both the eastern and western boundaries using TOPEX/POSEIDON data over short time periods. In this present work, we are first interested in computing long equatorial wave amplitudes over a much longer period (October 1992-May 1998) focusing on the Kelvin and first three largest Rossby waves. Secondly, we are examining qualitatively potential theories of ENSO in the light of observations of the strong 1997-1998 El Niño event. At the eastern boundary, Kelvin waves are observed to reflect into first (third) mode Rossby waves with a reflection efficiency of 75% (65%) of that of an infinite meridional wall. In the western Pacific Ocean, the reflection of the first Rossby wave does explain more than 90% of the Kelvin wave variance. The second Rossby wave is found not to be correlated to the Kelvin wave amplitude, and the third Rossby wave is highly correlated to the Kelvin signal although its contribution is weak. The investigation during the 1997-1998 event of two theories potentially important for ENSO (the delayed action oscillator mechanism and the recent theory of Picaut et al., 1997) led us to the following conclusions. The westerly wind anomalies observed in the western Pacific in December 1996 and March 1997 forced downwelling Kelvin waves which advected the eastern edge of the warm pool eastward and deepened the thermocline in the east Pacific. Both zonal advection and vertical processes are suggested to act constructively during the onset of positive anomalies in the central and eastern Pacific. From May to September 1997, downwelling Kelvin wave wind-forced in the central Pacific and reflected downwelling Rossby waves (reinforced by local easterly wind anomalies) acted against each other, and the 28°C isotherm was found to move slightly westward. In October 1997, strong westerly wind anomalies forced a strong downwelling Kelvin wave potentially responsible for the strong warming in the east Pacific. The 28°C isotherm reached the eastern boundary. At that time, the equatorial sea surface temperatures are zonally homogeneous. The strong downwelling Rossby waves reflected at the boundary could not act to terminate the warm event through zonal advection as suggested by Picaut et al. However the reflected upwelling Kelvin waves coming from the western boundary weakened the downwelling Kelvin signal in the central and east Pacific leading to a decrease of the sea surface temperature anomalies. Following this decrease, westerly wind anomalies in the central Pacific weakened, and upwelling Kelvin waves reinforced by easterly wind anomalies in the western Pacific propagated toward the eastern Pacific. As a conclusion, both theories must be considered simultaneously to understand the variability observed during the 1997-1998 El Niño event. However observations strongly suggest the delayed action oscillator mechanism to be the major process at work during the weakening of the warm 1997-1998 ENSO.

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• Type de publi. : Chapître d'ouvrage
• Date de publi. : 01/01/1999
• Auteurs : Philippe Sénac
• Organismes : France, Amériques, Espagne, Sociétés, Pouvoirs, Acteurs

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• Type de publi. : Communication dans un congrès
• Date de publi. : 01/01/1999
• Auteurs : J.L. ZaraderBruno GasPhilippe DrobinskiP. Dabas
• Organismes : Institut des Systèmes Intelligents et Robotique Sorbonne Université Institut des Systèmes Intelligents et Robotique Laboratoire de Météorologie Dynamique (UMR 8539)

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• Type de publi. : Rapport
• Date de publi. : 01/01/1999
• Auteurs : Pierre AndriesPatrick Le TallecJean-Philippe PerlatBenoît Perthame
• Organismes : Multi-Models and Numerical Methods Multi-Models and Numerical Methods Multi-Models and Numerical Methods

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Résumé : In this paper we prove the entropy inequality for the Gaussian-BGK model of Boltzmann equation. This model, also called ellipsoidal statistical model, was introduced in order to fit realistic values of the transport coefficients (Prandtl number, second viscosity) in the Navier-Stokes approxima- tion, which cannot be achieved by the usual relaxation towards isotropic Maxwellians introduced in standard BGK models. Moreover, we introduce new entropic kinetic models for polyatomic gases which suppress the internal energy variable in the phase space by using two distribution functions (one for particles mass and one for their internal energy). This reduces the cost of their numerical solution while keeping a kinetic description well adapted to desequilibrium regions.

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Fichiers liés : RR-3716.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/1999
• Auteurs : Philippe BiaginiPierre GallianHoussam AttouiJean-François CantaloubePhilippe de MiccoXavier de Lamballerie
• Organismes : Virologie UMR1161
• Publié dans Journal of General Virology le 01/11/2020

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