Philippe JEAN-PIERRE

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• Type de publi. : Communication dans un congrès
• Date de publi. : 01/06/2008
• Auteurs : Philippe AngotJean-Paul CaltagironePierre Fabrie
• Organismes : Laboratoire d'Analyse, Topologie, Probabilités Transferts, écoulements, fluides, énergétique Institut de Mathématiques de Bordeaux

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Résumé : A new family of methods, the so-called two-parameter {\em vector penalty-projection} (VPP$_{r,\eps}$) methods, is proposed where an original {\em penalty-correction step} for the velocity replaces the standard scalar pressure-correction one to calculate flows with divergence-free velocity. This allows us to impose the desired boundary condition to the end-of-step velocity-pressure variables without any trouble. The counterpart to pay back is that in these methods, the cons\-traint on the discrete divergence of velocity is only satisfied approximately as $\cO(\eps\dt)$ within a {\em penalty-correction step} and the penalty parameter $0<\eps\leq 1$ must be decreased until the resulting splitting error is made negligible compared to the time discretization error. However, the crucial issue is that the linear system associated with the projection step can be solved all the more easily as $\eps\dt$ is smaller. Finally, the {\em vector penalty-projection method} (VPP$_{r,\eps}$) has several nice advantages: the Dirichlet or open boundary conditions are not spoiled through a scalar pressure-correction step. Moreover, this method can be generalized in a natural way for variable density or viscosity flows and we show that the vector correction step can be made quasi-independent on the density or viscosity variables (and also on the non-linear terms) if $\eta=\eps\dt$ is taken sufficiently small. These terms can be then neglected in practical schemes.

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Fichiers liés : fvca5_ACF08.pdf

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• Type de publi. : Communication dans un congrès
• Date de publi. : 29/05/2008
• Auteurs : Jean-Luc BarayRobert DelmasYann CourcouxJean-Marc MetzgerH. FerréFranck GabarrotPhilippe KeckhutJacques Porteneuve
• Organismes : Laboratoire de l'Atmosphère et des Cyclones Laboratoire de l'Atmosphère et des Cyclones Laboratoire de l'Atmosphère et des Cyclones Laboratoire de l'Atmosphère et des Cyclones Laboratoire de l'Atmosphère et des Cyclones Service d'aéronomie Service d'aéronomie

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Résumé : Communication about L'OPAR (Observatoire de Physique de l'Atmosphère de la Réunion), un site privilégié pour l'étude de l'atmosphère tropicale : parc instrumental, résultats scientifiques et projets

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• Type de publi. : Communication dans un congrès
• Date de publi. : 26/05/2008
• Auteurs : S. HanafiZ. AbdelazizJean-Claude MailholPhilippe Le GrussePierre RuelleJean Christophe Poussin
• Organismes : Institut National de Recherche en Génie Rural Eaux et Forêts Gestion de l'Eau, Acteurs, Usages Gestion de l'Eau, Acteurs, Usages Centre International de Hautes Etudes Agronomiques Méditerranéennes - Institut Agronomique Méditerranéen de Montpellier Gestion de l'Eau, Acteurs, Usages Centre International de Hautes Etudes Agronomiques Méditerranéennes - Institut Agronomique Méditerranéen de Montpellier

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Résumé : Accurate estimation of water demand at the irrigation scheme scale is a key requirement for water management, which is made difficult by the large diversity of crops and production systems. The main objective of this study was to estimate irrigation water demand at the farm scale, taking different types of knowledge into account: (i) database study, where water demand is supposed to be the supply (L0); (ii) actual cropping pattern (L1),; (iii) actual irrigation techniques and cropping pattern (L2); and (iv) actual irrigation practices, actual irrigation techniques, and cropping pattern (L3). Farm typology makes easy this estimation as it takes into account various farm characteristics. Firstly, a farm typology was established based on 115 farms surveyed in the irrigation scheme of Borj Toumi Toungar (Tunisia), selected for the study. Secondly, climatic crop water irrigation requirements were estimated using the agro-meteorological water balance model Pilote. Typology results were used to estimate water demand at the scale of family farms taking into account different levels of knowledge Six classes of farming areas were identified based on irrigation subsystems, cropping pattern (fruit tree area, cropping vegetable area and field crop area), intensification crop level and cropped surface. Results showed that supply could not entirely cover the climatic water demand. However, it could nearly meet actual water demand at the farm scale. According to the water demand estimation at different levels, results showed that there were few changes in water demand at farm scale when moving from L1 to L2. At the opposite, actual water demand (L3) represented about half the climatic water demand (L2). Calculations based on farm classes highlighted the importance of actual farm practices. Within the same class, the difference between water demand estimation at different levels of knowledge was remarkable. Network rehabilitation is thus necessary to enable farmers to increase water delivered to crops and limit water stress; the collective network was conceived to deliver a flow of 0.34 l/s/ha in this sector. Given changes in farming and varietal choices, this flow proved insufficient to face the climatic water demand.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 26/05/2008
• Auteurs : S. OmariJ.-P. BordA. BouazizPhilippe Le GrusseJean Christophe PoussinPierre Ruelle
• Organismes : Centre International de Hautes Etudes Agronomiques Méditerranéennes - Institut Agronomique Méditerranéen de Montpellier Cités, Territoires, Environnement et Sociétés Institut Agronomique et Vétérinaire Hassan II Centre International de Hautes Etudes Agronomiques Méditerranéennes - Institut Agronomique Méditerranéen de Montpellier Gestion de l'Eau, Acteurs, Usages Gestion de l'Eau, Acteurs, Usages

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Résumé : Depuis un siècle, la création de réseaux collectifs d'irrigation a été un moyen au service de la puissance publique pour atteindre ses objectifs de politique agricole et d'aménagement du territoire. En 1961, l'office national des irrigations s'est fixé une doctrine de l'intervention en matière de développement hydro agricole : priorité à la grande hydraulique, création de grands périmètres irrigués, mise au point d'un modèle d'aménagement, introduction des cultures sucrières et du contrat de cultures entre l'Etat et les agriculteurs, création de structures locales d'intervention plus proches des agriculteurs (les centres de mise en valeur). Ce modèle technique de l'aménagement hydro-agricole, notamment dans le périmètre irrigué du Gharb, résolvait, avec élégance, le problème majeur de l'articulation et de la gestion de nombreuses données dans un aménagement intégré : satisfaction des besoins en eau, disposition des cultures et des propriétés de façon à permettre le respect de l'assolement préconisé et la distribution des doses d'eau appropriées aux besoins des cultures. Le début des années1990 a été marqué par le désengagement de l'Etat du suivi de la gestion des périmètres irrigués et la libéralisation des assolements. Ainsi, libres dans leurs choix de production, les agriculteurs ont transformé leur système de production pour faire face à la nouvelle conjoncture économique (signature des accords de libre échange avec l'Europe et les USA, etc.). Dans ce nouveau contexte, le rôle des offices régionaux de mise en valeur agricole (Ormva) s'est limité à la prestation du service de vente de l'eau d'irrigation, de la gestion du réseau d'irrigation et de l'encadrement des agriculteurs. Les Ormva, se sont trouvés incapables de suivre la quasi-totalité des agriculteurs faisant partie de leur zone d'action. Cela est dû d'une part, à l'immensité des périmètres irrigués et, d'autre part, au manque de moyens humains et logistiques mis à la disposition des Ormva. La représentation cartographique reste le meilleur outil de la présentation de l'espace, mais pour la rendre dynamique, et en faire un outil de la création de dialogue entre les acteurs il faut lui donner un caractère dynamique. Une première analyse du système d'information de l'Ormva du Gharb a montré l'existence de nombreuses informations sur les cultures pratiquées, les consommations en eau qui peuvent générer de la connaissance sur ce qui se passe réellement sur le périmètre, mais ces informations sont dispersées dans les différents services, entre lesquels la circulation de ces données est presque inexistante. Ces données ne sont pas exploitées, ni vérifiées à cause de la difficulté de l'outil de gestion des données mis en place par l'Ormva et de l'immensité de l'effectif des détenteurs de codes (agriculteurs). Pour faire face à cette situation, la mise en place d'un dispositif d'observation territorial demeure une démarche indispensable pour la gestion des périmètres irrigués. Pour surmonter le problème d'accès à l'information, il est préconisé de mettre en place une cellule d'observation, qui sera formée des agents de plusieurs départements de l'Ormva, ce qui facilitera la disponibilité, la fluidité, le traitement des données et la circulation de l'information.

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Fichiers liés : Omari.pdf

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• Type de publi. : Communication dans un congrès
• Date de publi. : 26/05/2008
• Auteurs : Jean-Philippe DacquinPierre MiquelChristophe DujardinSylvain CristolSergey I. NikitenkoWim BrasPascal Granger
• Organismes : Unité de Catalyse et Chimie du Solide - UMR 8181 Unité de Catalyse et Chimie du Solide - UMR 8181 Unité de Catalyse et Chimie du Solide - UMR 8181 Laboratoire de catalyse de Lille - UMR 8010 Unité de Catalyse et Chimie du Solide - UMR 8181 Laboratoire de catalyse de Lille - UMR 8010 DUBBLE DUBBLE Unité de Catalyse et Chimie du Solide - UMR 8181 Laboratoire de catalyse de Lille - UMR 8010

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• Type de publi. : Communication dans un congrès
• Date de publi. : 26/05/2008
• Auteurs : Salia HanafiZaïri AbdelazizJean-Claude MailholPhilippe Le GrussePierre RuelleJean Christophe Poussin
• Organismes : Gestion de l'Eau, Acteurs, Usages Institut National de Recherche en Génie Rural Eaux et Forêts Gestion de l'Eau, Acteurs, Usages Gestion de l'Eau, Acteurs, Usages Centre International de Hautes Etudes Agronomiques Méditerranéennes - Institut Agronomique Méditerranéen de Montpellier Gestion de l'Eau, Acteurs, Usages Gestion de l'Eau, Acteurs, Usages

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Résumé : Accurate estimation of water demand at the irrigation scheme scale is a key requirement for water management, which is made difficult by the large diversity of crops and production systems. The main objective of this study was to estimate irrigation water demand at the farm scale, taking different types of knowledge into account: (i) database study, where water demand is supposed to be the supply (L0); (ii) actual cropping pattern (L1),; (iii) actual irrigation techniques and cropping pattern (L2); and (iv) actual irrigation practices, actual irrigation techniques, and cropping pattern (L3). Farm typology makes easy this estimation as it takes into account various farm characteristics. Firstly, a farm typology was established based on 115 farms surveyed in the irrigation scheme of Borj Toumi Toungar (Tunisia), selected for the study. Secondly, climatic crop water irrigation requirements were estimated using the agro-meteorological water balance model Pilote. Typology results were used to estimate water demand at the scale of family farms taking into account different levels of knowledge Six classes of farming areas were identified based on irrigation subsystems, cropping pattern (fruit tree area, cropping vegetable area and field crop area), intensification crop level and cropped surface. Results showed that supply could not entirely cover the climatic water demand. However, it could nearly meet actual water demand at the farm scale. According to the water demand estimation at different levels, results showed that there were few changes in water demand at farm scale when moving from L1 to L2. At the opposite, actual water demand (L3) represented about half the climatic water demand (L2). Calculations based on farm classes highlighted the importance of actual farm practices. Within the same class, the difference between water demand estimation at different levels of knowledge was remarkable. Network rehabilitation is thus necessary to enable farmers to increase water delivered to crops and limit water stress; the collective network was conceived to deliver a flow of 0.34 l/s/ha in this sector. Given changes in farming and varietal choices, this flow proved insufficient to face the climatic water demand.

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Fichiers liés : 21_Hanafi.pdf

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• Type de publi. : Communication dans un congrès
• Date de publi. : 25/05/2008
• Auteurs : Adrien UgonCarole PhilippeSlawomir PietraszJean-Gabriel GanasciaPierre Lévy
• Organismes : Agents Cognitifs et Apprentissage Symbolique Automatique Agents Cognitifs et Apprentissage Symbolique Automatique

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Résumé : OPTISAS is a visualization method that allows describing very precisely a patient with Sleep Apnea Syndrome. Using the events scored by the physician, our method gives a set of graphs that are a detailed representation of the condition, sleep stage and position, in which the events occur. This helps for the diagnosis. This is possible thanks to the application of Generalized Caseview method. The method proceeds in two steps, defining the reference frame and using this reference frame to visualize data. The reference frame is built by using a supin/unsupine binary criterion, a six type event criterion and a sleep stage ordinal criterion. The main result is the visualization of the indexes (average number of events by hour) associated with the events. This allows a more accurate diagnosis showing the precise influence of the position and of the sleep stage on the events.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 22/05/2008
• Auteurs : Luc MultignerPhilippe KadhelFarida Huc-TerkiE. DelverEustase JankyJean-Pierre ThomeSylvaine CordierPascal Blanchet
• Organismes : Groupe d'Etude de la Reproduction Chez l'Homme et les Mammiferes Service de gynécologie-obstétrique Service de gynécologie-obstétrique Laboratory of Animal Ecology and Ecotoxicology Groupe d'Etude de la Reproduction Chez l'Homme et les Mammiferes Groupe d'Etude de la Reproduction Chez l'Homme et les Mammiferes Service d'urologie

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• Type de publi. : Communication dans un congrès
• Date de publi. : 20/05/2008
• Auteurs : Benjamin BoisCornelis van LeeuwenPhilippe PieriJean-Pierre GaudillèreEtienne SaurDaniel JolyLucien WaldDidier Grimal
• Organismes : Ecophysiologie et Génomique Fonctionnelle de la Vigne Ecophysiologie et Génomique Fonctionnelle de la Vigne Ecophysiologie et Génomique Fonctionnelle de la Vigne Ecophysiologie et Génomique Fonctionnelle de la Vigne Transfert Sol-Plante et Cycle des Eléments Minéraux dans les Ecosystèmes Cultivés Théoriser et modéliser pour aménager (UMR 6049) CEP/Sophia Météo-France Direction interrégionale Sud-Ouest

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Résumé : Climate is a key variable for grapevine development and berry ripening processes. At mesoscale level, climate spatial variations are often determined empirically, as weather station networks are generally not dense enough to account for local climate variations. In this study, climate spatial variations of Bordeaux winegrowing area were assessed by means of solar radiation cartography using satellite sensing and Digital Elevation Model (DEM) information, daily temperature interpolation using weather station and terrain information, spatialized rainfall using rain gauge data and kriging techniques. Temperature and solar radiation data were used to generate evapotranspiration maps at daily time step. Spatialized data was used to characterize the production potential of several zones of Bordeaux winegrowing areas, according to their agroclimatic characteristics. Temperature differences within Bordeaux vineyards induce considerable discrepancies in vine phenology, as is shown by means of a degree.day model. Solar radiation data and potential evapotranspiration are mostly governed by terrain characteristics (slope and aspect). Rainfall data spatial patterns indicate that the north-western part of Bordeaux vineyards is recurrently drier and the south-western receives higher rainfall amounts during the grapevine growing season. However, spatial distribution of summer rainfall events changes considerably from one year to another. The results of this study offer useful information to adapt grapevine cultivars and vineyard management to local climate.

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Fichiers liés : CI42.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 13/05/2008
• Auteurs : M. ChliehJean‐philippe AvouacK. SiehD.H. NatawidjajaJ. Galetzka
• Organismes : Géoazur Tectonics Observatory Tectonics Observatory Tectonics Observatory Tectonics Observatory
• Publié dans Journal of Geophysical Research : Solid Earth le 27/10/2020

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Résumé : Geodetic and paleogeodetic measurements of interseismic strain above the Sumatran portion of the Sunda subduction zone reveal a heterogeneous pattern of coupling. Annual banding in corals provides vertical rates of deformation spanning the last half of the 20th century, and repeated GPS surveys between 1991 and 2001 and continuous measurements at GPS stations operated since 2002 provide horizontal velocities. Near the equator, the megathrust is locked over a narrow width of only a few tens of kilometers. In contrast, the locked fault zone is up to about 175 km wide in areas where great interplate earthquakes have occurred in the past. Formal inversion of the data reveals that these strongly coupled patches are roughly coincident with asperities that ruptured during these events. The correlation is most spectacular for rupture of the Mw 8.7 Nias-Simeulue earthquake of 2005, which released half of the moment deficit that had accumulated since its previous rupture in 1861, suggesting that this earthquake was overdue. Beneath the Mentawai islands, strong coupling is observed within the overlapping rupture areas of the great earthquakes of 1797 and 1833. The accumulated slip deficit since these events is slowly reaching the amount of slip that occurred during the 1833 earthquake but already exceeds the slip that occurred during the 1797 earthquake. Thus, rerupture of part of the Mentawai patch in September 2007 was not a surprise. In contrast, coupling is low below the Batu islands near the equator and around Enggano island at about 5°S, where only moderate earthquakes (Mw < 8.0) have occurred in the past two centuries. The correlation of large seismic asperities with patches that are locked during the interseismic period suggests that they are persistent features. This interpretation is reinforced by the fact that the large locked patches and great ruptures occur beneath persistent geomorphologic features, the largest outer arc islands. Depth- and convergence-rate-dependent temperature might influence the pattern of coupling, through its effect on the rheology of the plate interface, but other influences are required to account for the observed along-strike heterogeneity of coupling. In particular, subduction of the Investigator Fracture Zone could be the cause for the low coupling near the equator.

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Fichiers liés : 2007JB004981.pdf

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