Billère – Lacaou

Identifiant de l'opération archéologique : 025048 Date de l'opération : 2007 (EV) La construction d’une vaste zone pavillonnaire est à l’origine de la fouille préventive qui s’est déroulée sur la commune de Billère, au lieu-dit Lacaou. Les vestiges archéologiques sont localisés sur le rebord d’une terrasse marquant l’extrémité septentrionale du Pont Long, à proximité d’une combe qui débouche sur la vallée du Gave de Pau. Compte tenu des résultats recueillis lors du diagnostic (Chopin, 2005), ..

Démonstration de faisabilité de la nitrification et de la dénitrification d'un lixiviat de lieu d'enfouissement sanitaire avec de la tourbe granulaire

Les lieux d'enfouissement sanitaire (LES) -- La tourbe -- Composés azotés -- Nitrification -- Facteurs influençant la nitrification -- Dénitrification -- Nitrification et dénitrification simultanée -- Caractérisation des lixiviats -- Caractérisation de la tourbe granulaire -- Caractérisation microbiologiqaue de la tourbe -- Essais de nitrification -- Essais de dénitrification -- Essais de nitrification et de dénitrification combinés -- Méthodes analytiques -- Caractéristiques chimiques de lixiviats -- Caractéristiques de la tourbe granulaire

Thermal Interface Conductance between Aluminum and Silicon by Molecular Dynamics Simulations

The thermal interface conductance between Al and Si was simulated by a non-equilibrium molecular dynamics method. In the simulations, the coupling between electrons and phonons in Al are considered by using a stochastic force. The results show the size dependence of the interface thermal conductance and the effect of electron-phonon coupling on the interface thermal conductance. To understand the mechanism of interface resistance, the vibration power spectra are calculated. We find that the atomic level disorder near the interface is an important aspect of interfacial phonon transport, which leads to a modification of the phonon states near the interface. There, the vibrational spectrum near the interface greatly differs from the bulk. This change in the vibrational spectrum affects the results predicted by AMM and DMM theories and indicates new physics is involved with phonon transport across interfaces. Keywords:Comment: Journal of Computational and Theoretical Nanoscience 201

Optical fibre coupling devices

This thesis deals with optical coupling systems and is divided in two parts. The first one is concerned with directional coupling between two graded index fibres made by a diffusion process. The theory and physics of ion exchange is studied, providing a theoretical description of the refractive index change. A mathematical method of solving the concentration dependent diffusion equation is given. Theoretical index distributions are thus obtained for circular waveguides. To compare theory with experiment, a device directly measuring the index profile of a circular fibre is described. The theory of propagation in round graded index fibres, is reviewed and a simplified coupling coefficient derived in order to determine the coupling efficiency. The coupling arrangement is described and the results discussed. It is shown that efficient tapping of power can be done with the high order modes, and eventually, at a much lower efficiency with the low order ones. The second part describes a theoretical study of optical contradirectional coupling between a single mode sandwich ribbon fibre and a thin film planar waveguide, longitudinal phase matching being achieved by means of a periodic corrugation, which is typically a grating etched into the film. Film-fibre couplers were tested and achieved an estimated efficiency of only due to the poor quality of the gratings. With several improvements in the set-up and specimens, an efficiency of over 60 is quite feasible. The application of the method for linking integrated optical devices is considered as well as a possible demultiplexer. The study presented provides the ground work for future development of integrated optical devices links and an active device

Arras – Quartier Morel

Un projet de construction d’immeubles sur la ville d’Arras a suscité la mise en place d’une opération de sondages archéologiques, afin de détecter la présence de vestiges d’occupations anciennes. Le terrain de ce projet se situe à l’est de la gare d’Arras, entre la route de Cambrai, la rue Maréchal De Lattre De Tassigny, la rue Beaumarchais et la rue Gustave Colin, sur le « Quartier Morel ». Le SAM d’Arras a été mandaté pour réaliser un diagnostic sur cette emprise. Aujourd’hui occupée par un..

Analyse expérimentale de l'effet de la texturation des patins sur le comportement des butées hydrodynamiques à géométrie fixe

La texturation de surface est une thématique récente qui suscite un certain engouement pour les contacts dynamiques. Pendant de nombreuses années, les tribologues ont privilégié les surfaces lisses aux faibles rugosités pour limiter le frottement. Inspiré des rugosités de surface organisées observées dans la nature, les topologies de surfaces sont désormais axées sur la texturation et la structuration des rugosités. Fort de ce potentiel, de nombreuses études traitent, par une approche numérique, la modélisation de ces surfaces et les études expérimentales sont rares, avec une instrumentation souvent insuffisante pour appréhender tous les phénomènes physiques. Par une approche expérimentale, nous analysons le comportement des butées hydrodynamiques à faces parallèles partiellement texturées. Les 80 capteurs équipant le dispositif d'essais permettent d'apprécier avec rigueur la phénoménologie à l'interface du patin et du film lubrifiant. L'analyse met l'accent sur la capabilité de ce composant à être intégré dans un environnement industriel. Afin d'objectiver les résultats, les campagnes d'essais sont menées sur dix butées hydrodynamiques dont quatre sont munies de texturation. Une comparaison de ces butées facilite leur classement en termes de capacité de charge, de réduction de frottement ou encore de risque d'usure dans les phases de démarrage. Pour les configurations étudiées, les butées texturées ne peuvent concurrencer les butées à poches ou à plans inclinés du point de vue de la capacité de charge. En se référant à une butée à faces parallèles, les butées texturées permettent une réduction du frottement de 30% à faibles charges tandis que pour de fortes charges, lesSurface texturing is a recent topic which has raised a great interest in contact dynamics. For many years, engineers have favored smooth surfaces with low roughness in order to minimize friction losses. Inspired by textured surfaces which can be commonly found in nature, the research in surface topography is now focused on texturing and roughness characterization. Considering the great potential of surface texturing, many research studies analyze this subject, most commonly theoretically, while experimental works are often performed with inadequate equipment which does not allow a proper evaluation of the involved physical phenomena. This study uses an experimental approach in order to analyze the behavior of hydrodynamic thrust bearings with parallel textured pads. The experimental device is equipped with 80 sensors which allow a proper assessment of the phenomenology at the film/pad interface. This analysis focuses on the capability of this textured component to be integrated in an industrial environment. To objectify the results, the tests are conducted on ten hydrodynamic thrust bearings, among which four are textured. The comparison between the performances of these bearings facilitates their classification in terms of load-carrying capacity, friction loss and wears resistance during the start-up period. Results show that for the studied configurations, the textured thrust bearings cannot compete with pocketed or tapered land thrust bearings in terms of load-carrying capacity. In the case of parallel thrust bearings, surface texturing can help to reduce friction up to 30% at low loads while for heavy loads, their performance is equivalent or even lower than that ofPOITIERS-SCD-Bib. électronique (861949901) / SudocSudocFranceF

Analysis of supersonic ejector operation : experimental validation and two-phase aspects

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.This paper deals with comparisons between CFD and experiments for a supersonic ejector. We present good results in terms of entrainment prediction compared to home-made experimental data for an air ejector. Over the whole range of operating conditions, the deviation is below 10%for the k−e model. In addition, a first attempt to tackle two-phase aspects was also performed experimentally and by simulations.cs201

Detection of Ongoing Mass Loss from HD 63433c, a Young Mini-Neptune

We detect Lyα absorption from the escaping atmosphere of HD 63433c, a R = 2.67R⊕, P = 20.5 day mini-Neptune orbiting a young (440 Myr) solar analog in the Ursa Major Moving Group. Using Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph, we measure a transit depth of 11.1 ± 1.5% in the blue wing and 8 ± 3% in the red. This signal is unlikely to be due to stellar variability, but should be confirmed by an upcoming second transit observation with HST. We do not detect Lyα absorption from the inner planet, a smaller R = 2.15R⊕ mini-Neptune on a 7.1 day orbit. We use Keck/NIRSPEC to place an upper limit of 0.5% on helium absorption for both planets. We measure the host star\u27s X-ray spectrum and mid-ultraviolet flux with XMM-Newton, and model the outflow from both planets using a 3D hydrodynamic code. This model provides a reasonable match to the light curve in the blue wing of the Lyα line and the helium nondetection for planet c, although it does not explain the tentative red wing absorption or reproduce the excess absorption spectrum in detail. Its predictions of strong Lyα and helium absorption from b are ruled out by the observations. This model predicts a much shorter mass-loss timescale for planet b, suggesting that b and c are fundamentally different: while the latter still retains its hydrogen/helium envelope, the former has likely lost its primordial atmosphere

Detection of ongoing mass loss from HD 63433c, a young mini-Neptune

L.D.S. and D.E. acknowledge that this project received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (project Four Aces grant agreement No. 724427), and it has been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). T.G.W. acknowledges support from STFC consolidated grant No. ST/R000824/1. S.H. acknowledges CNES funding through the grant 837319. S.H. acknowledges CNES funding through the grant 837319. G.W.H. acknowledges long-term support of the APT program from NASA, NSF, Tennessee State University, and the State of Tennessee through its Centers of Excellence Program.We detect Lyα absorption from the escaping atmosphere of HD 63433c, a R = 2.67R⊕, P = 20.5 day mini-Neptune orbiting a young (440 Myr) solar analog in the Ursa Major Moving Group. Using Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph, we measure a transit depth of 11.1 ± 1.5% in the blue wing and 8 ± 3% in the red. This signal is unlikely to be due to stellar variability, but should be confirmed by an upcoming second transit observation with HST. We do not detect Lyα absorption from the inner planet, a smaller R = 2.15R⊕ mini-Neptune on a 7.1 day orbit. We use Keck/NIRSPEC to place an upper limit of 0.5% on helium absorption for both planets. We measure the host star’s X-ray spectrum and mid-ultraviolet flux with XMM-Newton, and model the outflow from both planets using a 3D hydrodynamic code. This model provides a reasonable match to the light curve in the blue wing of the Lyα line and the helium nondetection for planet c, although it does not explain the tentative red wing absorption or reproduce the excess absorption spectrum in detail. Its predictions of strong Lyα and helium absorption from b are ruled out by the observations. This model predicts a much shorter mass-loss timescale for planet b, suggesting that b and c are fundamentally different: while the latter still retains its hydrogen/helium envelope, the former has likely lost its primordial atmosphere.Publisher PDFPeer reviewe