De los paisajes de ayer a los paisajes de manana. Metodologia de un observatorio fotografico para el analisis de las dinamicas paisajisticas : el valle de Vicdessos, Pirineos de Ariège (Francia)

International audienceLos paisajes de la mayoría de las montañas europeas han conocido desde un siglo diná-micas muy rápidas y espectaculares, que se continúan a menudo y se aceleran hoy. la creación de observatorios del paisaje basados en el método de la fotografía repetida se convirtió en una herramienta muy usada para el seguimiento de las evoluciones paisajísticas. este artículo destaca la necesidad de adaptar el método de foto-comparación a una investigación específica sobre el paisaje. propone un «planteamiento fotográfico paisajística» orientado en función de objetivos de investigación básica y aplicada: conocimiento de los procesos y evoluciones paisajísticas, consecuencias en el tiempo y sobre el territorio, y también ayuda a los actores locales para el planeamiento y las políticas publicas del paisaje

How to protect groundwater catchments used for human consumption in karst areas?

International audienceThe natural variability of catchment waters in karst areas requires treatment in order to respect the turbidity limit in the water supply. This water treatment reduces the range to be expected from protection areas. The creation of immediate, main and satellite protection areas is necessary. The longitudinal extension proposed for the inner protection area is based on a water transit time of 2 hours for the highest speeds in the aquifer under consideration. Delineating the inner protection area in such a way serves as a buffer in the event of accidental pollution. The selected intervention timeline allows for the interruption of pumping and keeps extraction and treatment equipment safe. The implementation of an outer protection area corresponding to a caution area may supplement the protection

Vers un observatoire partagé des paysages du Parc national des Pyrénées. Méthodes et matériaux pour analyser et illustrer l'évolution des paysages sur le territoire du Parc

La présente contribution présente un travail de préfiguration d'un observatoire partagé des paysages du Parc national des Pyrénées. Il s'est agi d'élaborer et d'expérimenter une méthode d'observation qui rende compte des évolutions paysagères que connaît le territoire du Parc, mette en évidence les principaux enjeux en ce domaine et propose un processus de discussion et de concertation pour éclairer les choix à effectuer. La méthode proposée offre la possibilité de mettre en place, à l'échelle du Parc en entier (zone cœur et aire d'adhésion comprises), une " politique du paysage ", levier potentiel d'un projet de territoire durable qui s'appuieraient sur des fortes solidarités écologiques, sociales, économiques et culturelles, existantes ou à (re)créer

Experimental investigation of a two-stage oil-free domestic Air/Water heat pump prototype powered by an oil-free high-speed twin-stage radial compressor rotating on gas bearings

Domestic heat pumps have been identified as a key-technology to decrease the energy consumption of the domestic sector, which represents 29% of the world final energy consumption. Space & water heating represent more than two third of the domestic sector energy consumption in many countries. Next generation domestic heat pumps powered by oil-free high-speed radial compressors are expected to (a) be more efficient at rating operating points and in partial loads, (b) to match better the energy demand characteristics, (c) to be more compact and lighter, (d) more silent, and (e) to need lower refrigerant charges. As a first step towards the development of such advanced heat pumps, an oil-free twin-stage Air/Water domestic heat pump prototype powered by an oil-free high-speed twin-stage radial compressor has been developed and tested. The heat pump layout corresponds to a two-stage heat pump cycle with an open economizer. The two main functions of the economizer are (a) to separate the liquid from the gas before the second stage compressor inlet and offer a proper mixing process, and (b) to store the liquid refrigerant not located in the heat exchangers at a given time. This key-component has been coupled with the compression unit and improved through incremental experimental steps. The heat pump driven by an oil-free twin-stage radial compressor has been successfully tested at the rating operating point A-7/W35. The performance reached with the prototype is considered very promising and constitutes a breakthrough in the domain. This article describes the experimental setup, the Operating Point (OP) A-7/W35, the methodology applied for data analysis, followed by the results. The issues limiting the performance of the prototype are also identified and briefly documented

Le paysage dans tous ses états. Trente ans de recherches et d'actions publiques dans les Pyrénées.

International audienceDepuis la fin des années 1970, les Pyrénées ont été (et continuent d'être) un terrain partagé et un laboratoire expérimental pour toute une série de chercheurs menant des investigations dans le domaine de l'environnement et du paysage. Le temps et l'interdisciplinarité sont au cœur de cette entreprise collective. Les résultats de ces recherches ont bousculé nombre d'idées reçues sur le passé d'environnements et de paysages montagnards supposés peu modifiés et peu mobiles. Il s'agit ici plus particulièrement de voir comment ces recherches ont pu fournir matière à une problématisation de l'action contemporaine et constituer les bases d'une réflexion sur le développement durable des territoires pyrénéens. L'hypothèse centrale suppose que le problème qui est aujourd'hui posé aux gestionnaires est de penser et d'infléchir des évolutions à l'origine desquelles l'on trouve des phénomènes biophysiques et sociaux entremêlés et de se donner les moyens de maîtriser cette hybridité dans la durée

Experimental investigation of electrical domestic heat pumps equipped with a twin-stage oil-free radial compressor

The world energy consumption has dramatically increased since the end of the World War II. The main share of this energy comes from fossil fuel combustion. The worldwide domestic sector consumes about 30% of the global energy supply and the biggest share of that is dedicated to space and water heating. In this context where sustainable energy consumption is required to limit our impact on the environment and the climate, energy efficiency is a key factor to successfully transition to energy sobriety. Electrically-driven heat pumps are known to be a key technology to increase our energy efficiency. More efficient, more compact, more silent heat pumps, built with less raw material, and using lower refrigerant charges are needed. In electrically-driven heat pumps, the compression process is responsible for most of the energy losses. However, for decades now, the heat pump performance has been stagnating, mainly because of the compression process efficiency which has not been increasing significantly. Consequently, the improvement of the compression process is indeed needed. A new single-stage compression unit design has been developed, built, and tested in a previous thesis work. This current thesis work uses a twin-stage successor of the initial single-stage compression unit and tests it into two oil-free domestic heat pump prototypes. This work aims at studying the integration of the radial compression units in domestic heat pumps and at demonstrating their feasibility and potential. The tested prototypes are a twin-stage Air/Water domestic heat pump and a twin-stage Brine/Water domestic heat pump. Both of them are equipped with a twin-stage oil-free radial compression unit rotating on gas bearings. By which, the maximum rotor speed of the compression units is 180 krpm. Six stable operating points have been documented with the Air/Water heat pump prototype. More notably so, the operating point A-7/W35 has been reached and demonstrates a coefficient of performance of 2.36 for a heating power of 10.7 kW. The Brine/Water heat pump prototype has been used to perform partial tests of circuit improvements, in order to solve some of the issues observed on the Air/Water prototype. The analysis of the experimental results uses a mass and energy balance modeling approach to improve the level of understanding of the internal and non measurable flows in the heat pump circuits. This model also propagates the uncertainties of the measurements through the equations. New improvements and innovative circuit layouts, notably at the level of the economizer, a key-component of the two-stage heat pump circuit, are offered to integrate further the compression unit in the heat pump circuits, and to make the whole system more efficient, more compact, more silent, less demanding in raw materials and reducing the refrigerant charge needed for the heat pump cycle

Technical aspects of an impact acceleration traumatic brain injury rat model with potential suitability for both microdialysis and PtiO2 monitoring

This report describes technical adaptations of a traumatic brain injury (TBI) model-largely inspired by Marmarou-in order to monitor microdialysis data and PtiO2 (brain tissue oxygen) before, during and after injury. We particularly focalize on our model requirements which allows us to re-create some drastic pathological characteristics experienced by severely head-injured patients: impact on a closed skull, no ventilation immediately after impact, presence of diffuse axonal injuries and secondary brain insults from systemic origin...We notably give priority to minimize anaesthesia duration in order to tend to banish any neuroprotection. Our new model will henceforth allow a better understanding of neurochemical and biochemical alterations resulting from traumatic brain injury, using microdialysis and PtiO2 techniques already monitored in our Intensive Care Unit. Studies on efficiency and therapeutic window of neuroprotective pharmacological molecules are now conceivable to ameliorate severe head-injury treatment

L'observation environnementale au prisme du paysage. Dynamiques paysagères, actions territoriales et représentations socio-spatiales contemporaines dans le territoire de l'OHM Pyrénées-Haut Vicdessos

International audienceSome people in charge of the OHM Pyrénées Haut Vicdessos underwent a methodological piece of research, whose aim was to turn the very landscape into a borderline tool between natural and social sciences. One singular point was to include the socio-spatial representations of the localpeople into the frame, through a close observation of both their sensibilities and expectations. Our results disclosed the complexity of the links between the very landscape, the way people look at it, and politics. Besides, such research entitled the present locals to reassess first the way their territory has been set in the long run and, next, the cultural bases of the place. In its turn, such reassessment enables the discussions and thinking that are prerequisite to the sustainable development of the territory.Dans le cadre de l'Observatoire Hommes-Milieux Pyrénées-Haut Vicdessos a été engagée une réflexion méthodologique visant à faire du paysage un outil pour une analyse interdisciplinaire à l'interface entre sciences naturelles et sciences sociales. L'objectif général du projet est de développer une observation qui s'intéresse aux évolutions paysagères en lien avec les différentes politiques à effet environnemental et territorial qui ont été, qui sont en train ou dont il est projeté qu'elles soient mises en œuvre dans le Vicdessos. La prise en compte des représentations socio-spatiales constitue une des originalités de ce projet. Il s'agit de construire une observation, qui ne soit pas seulement fondée sur la matérialité des environnements et des paysages, mais qui prenne également en compte les représentations sociales, les attentes et les sensibilités des acteurs et des populations. Les résultats obtenus restent partiels. Mais, ils montrent d'ores-et-déjà toute la complexité des relations s'établissant, dans la durée, entre les formes paysagères, les regards portés sur les paysages et les actions et les politiques menées dans les domaines du territoire, de l'environnement, du patrimoine ou du tourisme. La démarche utilisée permet en outre de placer les acteurs contemporains face à une histoire des modes d'actions sur l'espace et de leurs fondements culturels, afin de créer les conditions d'une concertation permettant l'émergence de valeurs partageables, fondements d'une réflexion sur le développement local et durable du territoire