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International audience ; The reconstruction of past climate variability offers important information about our climate system. Ice cores extractedfrom polar ice sheets or from mountainous glaciers are among the most popular climate archives. Ice cores from Andean glaciersin South America have been studied since the 1980’s. Almost ten ice cores have been extracted from the equator to Patagonia. Theycover different time periods from the last century to the last glacial-interglacial termination that started 21,000 years ago. Those icecores are usually dated by using a combination of methods: annual layers counting in both isotopic and chemical ice composition,radionuclides concentration analysis to detect atmospheric nuclear tests during the 20th century and ice flow modeling for the deepestpart of those cores. This paper presents two interesting results arising from the isotopic composition of the ice. The first one dealswith the isotopic records of Bolivian (Illimani) and Peruvian (Quelccaya) ice cores in regards to the reconstruction of glacier extentduring the little ice age in the 17th-18th century. Both approaches suggest a slightly moister and cooler period from 1650 to 1780. Thesecond result arises from the 120-year long isotopic record of an ice core drilled in Patagonia (San Valentin). It suggests that at theregional scale, temperature has regularly decreased of about 0.2 °C per decade, extending the temperature decrease shown by Chileanmeteorological data since the 1970’s despite a global warming. ; Reconstruire les variations passées de notre climat permet de mieux appréhender le fonctionnement de notre système climatique.Les carottes de glace issues des calottes polaires et des glaciers montagneux de haute altitude sont de très bonnes archivesclimatiques. Les glaciers présents sur les sommets des Andes sud-américaines sont ainsi exploités depuis les années 80. Une dizainede carottages ont été réalisés depuis l’équateur jusqu’en Patagonie. Ils recouvrent des périodes très différentes allant du ...

Face à ses engagements importants pris en ce qui concerne la réduction des émissions, la Chine a, un besoin urgent, d'établir un mécanisme d'échanges de quota d’émission pour atteindre l’objectif environnemental avec un minimum de coûts sociaux. Ce travail est de rechercher des propositions rationnelles en s'inspirant des expériences européennes et américaines. La comparaison sur les théories, les principes et la pratique des échanges des quotas d'émissions permet de connaître de manière plus globale les systèmes et d'avancer des propositions intéressantes visant à déterminer la conception d’un système de droits d’émission le plus approprié à la situation en Chine.A notre avis, un système d’échange des quotas d’émission chinois doit être promu progressivement, en passant d’un système volontaire à un système obligatoire, de marchés régionaux à un marché carbone national unifié. La réalité en Chine : deux types d’unités échangeables devront coexister dans le marché carbone. Un plan de mise en oeuvre devra être développé d’ici à 2020pour réussir à construire un système d'échanges des quotas d'émissions en Chine. ; Meet its important commitments regarding the reduction of emissions, China has an urgent need to establish an emission trading system to achieve the environmental objective with minimal social costs. This work is to researcher rational proposals, drawing on European and American experiences.Comparisons of theories, principles and practice of existing emission trading programs in order to find a more comprehensive systems. Proposals were made to examin the design of an emission trading system more appropriate tothe situation in China.In our opinion, a Chinese emission trading system should be promoted gradually, moving from a voluntary to a mandatory system, and from regional markets to a unified national carbon market. To achieve this goal, two types oftradable units will have to coexist in the carbon market. An implementation plan was developed to aid in building a successful emission trading system in ...

Données expérimentales: Deux jeux de données sur un profil de micro-cogénération sont proposés sur une pile à combustible de type PEM de 1kW composée de 8 cellules. Ces profils sont fonction de la puissance consommée par l'utilisateur selon la saison. Le premier jeu de données a été réalisé sur 1 000 heures, le second a été réalisé sur 500 heures (profil accéléré). Des caractérisations de type courbes de polarisation et spectres d'impédance électrochimiques ont été réalisées périodiquement afin d'évaluer la dégradation. Experimental data: Two sets of data on a micro-cogeneration profile are proposed and performed on a 1 kW and 8-cells PEM fuel cell. These profiles are function of the power consumed by the user according to the season. The first set of data has been realized on 1000 hours, the second one has been realized on 500 hours (accelerated profile). Characterizations such as polarization curves and electrochemical impedance spectra have been performed periodically to evaluate the degradation. Le projet PROPICE vise principalement à développer des méthodes intelligentes de PHM (Prognostics & Health Management) afin de suivre l'état de santé et d'estimer la durée de vie des systèmes pile à combustible à membrane échangeuse de protons. The main objective of the PROPICE project is to develop intelligent PHM (Prognostics & Health Management) methods to monitor the health status and estimate the lifetime of proton exchange membrane fuel cell systems. Project: PROPICE - PROgnostics et health management de systèmes PIles à CombustiblE, PROGELEC (French National Agency for Research) Audience: University: master, Research, University: licence Label: PHE (Plateforme Hydrogène-Energie) Label: Plateforme UBFC (Plateforme UBFC) UpdatePeriodicity: no update

The pinewood nematode (PWN) Bursaphelenchus xylophilus, native to the USA, is responsible of the pine wilt disease, causing large economic losses in the pine forests of all countries where it has been introduced. It uses as vector an insect of the genus Monochamus, e.g. M.galloprovincialis in Europe The objective of this thesis is to provide information about the dispersalabilities of, this beetle in order to better predict the spread rate of the PWN. Using flight mill experiments, we showed that immature adult beetles were able to fly since their emergence. The meanflight performance was ca. 500m per day, increasing with weight gain during the maturation period.There was no trade-offs in energy allocation between reproduction and dispersion. We therefore suggest that M. galloprovincialis is both "income breeder" and "capital disperser". Mature beetles were able to fly a total of 16km on average during their lifetime, with individual flights of ca. 1km. Flight performances increased with age and body weight, being equal for males and females. Because flight capacity remained constant across time, we suggested that the total distance potentially covered by beetles was mainly driven by their longevity. In a rearing experiment under controlled conditions we estimated the adult lifespan at 4 months. It was reduced under temperature regime with higheryearly thermal fluctuations. These results have important implications for the management of the PWN since they demonstrate that precautionary clear-cuts of 500m radius are likely to be ineffective in eradicating the disease. Le nématode du pin Bursaphelenchus xylophilus, originaire des Etats-Unis, est responsable de dépérissements massifs dans les forêts de pin des pays où il a été introduit. Il utilise comme vecteur un insecte du genre Monochamus, notamment M. galloprovincialis en Europe. L’objectif de cette thèse est de fournir des informations concernant les capacités de dispersion de ce coléoptère afin de mieux prédire le risque d'invasion. A l'aide d'expériences en manège de vol, nous avons montré que les adultes émergents, encore immatures, sont déjà en mesure de maintenir des vols soutenus. Ils peuvent parcourir une distance d'environ 500m par jour et les capacités de vol augmentent avec la prise de poids pendant la phase de maturation sexuelle. Il n'existe pas de compromis d'allocation de l'énergie entre fonctions de dispersion et de reproduction pendant cette période et nous proposons de qualifier ces insectes de "income breeder" et "capital disperser". A l'état mature M. galloprovincialis est capable de voler un total de 16 km, avec des vols individuels d'environ1 km; ces performances augmentent avec l'âge et le poids des insectes. Le maintien des capacités de vol tout au long de la vie adulte de M. galloprovincialis conduit à proposer que les distances potentiellement parcourues dépendent surtout de la longévité de l'insecte. Dans une expérience d'élevage en conditions contrôlées nous avons montré que la vie adulte dure au moins 4 mois, augmentant quand les fluctuations thermiques sont atténuées. Ces résultats ont des implications pour la gestion de B. xylophilus en Europe puisqu'ils démontrent que la méthode d'éradication par coupe rase sur un rayon de 500m est probablement inopérante.

fin de rédaction en avril 2007. Pas retouché. ; This thesis is the first such work in France on a-Si:H/c-Si heterojunction solar cells. This technology is based on the deposition of amorphous silicon onto crystalline silicon substrates, thus enabling the fabrication of high efficiency solar cells entirely at low temperatures (< 200 °C). It also makes it possible to process very thin c-Si substrates (<150 μm). In this work, we have dealt exclusively with p-type doped c-Si substrates, upon which a-Si:H, pm-Si:H or μc-Si layers have been deposited by RF-PECVD. We have paid particular attention to the ITO deposition, the cleaning procedure steps, and the resulting reproducibility issues. Industrialization was one of the goals of the research; hence, solar cells with large areas (25 cm2) and using a low-cost, screen-printed metallization step were developed. Power conversion efficiencies of the resulting cells were improved from 9 % to 17 % and record values of Voc between 660 mV and 677 mV were achieved. An outstanding quality of passivation (surface recombination of 16 cm/s averaged over 25 cm2) has been obtained. We have carried out in-situ ellipsometric measurements, SIMS, HR-TEM, capacitance measurements, and numerical simulations in order to gain further insight in the poorly understood physics of heterojunction solar cells. Original results have been obtained, and as well, some existing paradoxes have been resolved concerning the role of “ion bombardment”, the impact of epitaxial growth, and the behaviour of band offsets. One of our major conclusions is that the band offsets of a-Si:H/c-Si heterojunctions are not constant and are especially governed by hydrogen content. This discovery opens the door to the possibility of engineering heterojunction band offsets. ; Cette thèse a initié en France la thématique des cellules solaires à hétérojonctions a-Si:H/c-Si. Cette technologie consiste à déposer des couches de silicium amorphe sur des substrats de silicium cristallin ce qui présente l'avantage (par ...

Environmental systems are and will be more affected by climate change. Predicting the future dynamics of these complex systems in the context of climate change is necessary and represents a considerable challenge for the scientific community in order to support public policies in their decisions. In this context, tools and methods have been developed to solve these challenges. The work presented in this thesis focuses mainly on groundwater seepage and the impact it can have on coastal systems at low elevations. Beyond their characterisation, the aim is also to show the interest of considering them fully in the processes of the hydrological cycle through the control that they exert on the groundwater circulations. The different studies in this thesis have shown that the modelling of groundwater resurgence is necessary to characterise the future evolution of vulnerable areas in a coastal and climate change context. In other contexts, these resurgences are very useful for the characterisation of aquifers by the possibility to use them as reference data to estimate hydrodynamic properties. ; Les systèmes environnementaux sont et seront davantage affectés par les évolutions climatiques. Prédire les dynamiques futures en lien avec le changement climatique de ces objets complexes est nécessaire et représente un enjeu considérable pour la communauté scientifique afin d’accompagner les politiques publiques dans leurs décisions. C’est dans ce contexte que des outils et méthodes ont été développés pour répondre à ces enjeux. Les travaux présentés dans cette thèse s’articulent principalement autour des résurgences d’eau souterraine et l’impact qu’elles peuvent avoir sur les systèmes côtiers à faibles altitudes. Au-delà de leur caractérisation, il est aussi question de montrer l’intérêt de les considérer pleinement dans les processus du cycle hydrologique à travers le contrôle qu’elles exercent sur les circulations souterraines. Les différentes études de cette thèse ont démontré que la modélisation des résurgences d’eau ...

The Normandy region is prone to gravitational movements of various kinds (mudflows, rockfalls, rotational or translational landslides, etc.). The Pays d'Auge, at the contact between the Armorican Massif and the Paris Basin, is particularly concerned by these processes, due to a wide lithological variability and the sensitivity of materials to the presence of water. Many researches have been carried out in hinterland and coastal areas, contributing to the understanding of the landforms and the processes at work.Within the framework of the ANR RICOCHET program, this PhD thesis aims to provide some answers regarding the hazard assessment, both in terms of predisposing and triggering factors. The studied area extends specifically at the coastal and hinterland fringe of the Pays d'Auge, in the lower valley of the Touques river.Using a multidisciplinary approach combining geomorphology, geophysics, hydrogeology and geotechnics, investigations were carried out on three representative sites of landslide phenomena affecting this territory. By using existing data sets, completed by new acquisitions, this work aims to improve the knowledge of the hydromechanical functioning of each major type of landslide considered. The stability of the sites was assessed using numerical models based on finite element (SLOPE/W®) and finite difference (FLAC®) methods. A spatialized assessment of the susceptibility and hazard is then carried out at a larger scale (1:10,000) by the joint use of (1) a physically based model to simulate the triggering probability (ALICE®) and (2) an empirical model for the propagation (Flow-R®). The landslide sensitivity is highlighted with respect to current forcing, and considering the expected influence of climate change. ; La région Normandie est sujette aux mouvements gravitaires de diverses natures (coulées de boues, éboulements, glissements de terrain rotationnels ou translationnels, etc.). Le Pays d’Auge, au contact entre Massif armoricain et Bassin parisien, est particulièrement affecté par ces ...

In the context of climate change, Arctic marine ecosystems are affected by rapid environmental modifications, whose effects on biotic communities are still debated. The sea-ice decline and the increase in freshwater inputs and turbidity are likely to impact Arctic primary producers, with cascade effects on a key-process in those ecosystems: the trophic relationship between primary producers and benthic consumers (generally referred as “pelagic-benthic coupling”). The direct study of such complex interaction is not straightforward in the Arctic. The biological model of filter-feeding bivalves offers the possibility to get around these problems, allowing to study those ecological processes indirectly. Among the advantages of this model, there is first of all the fact that these organisms record in their shell, in the carbonate layers, some dynamics of their environments. The information recorded in such “bioarchives” are interpreted through the methods of sclerochronology and sclerochemistry and relate to a time window corresponding to the organism lifespan (from some years to more than 500 years). Given that these organisms are primary consumers, another advantage of this biological model is that the study of their diet can provide information about the trophic relationship with primary producers. With the methods of trophic ecology, especially fatty acids and stable isotopes, the study of the tissues allows the investigation of sources assimilated at a timescale of weeks/months.The main objective of this thesis is to test the potential of bivalves Astarte moerchi (borealis complex) as a biological model for the study of marine Arctic ecosystems. A coupled approach is used to combine shell analysis by the methods of sclerochronology and sclerochemistry (elemental ratios) and tissue analysis by the methods of trophic ecology (fatty acids, carbon and nitrogen stable isotopes, compound-specific carbon stable isotopes on individual fatty acids). Two living A. moerchi populations have been studied in two fjords ...

Le fractionnement par voie sèche des agroressources : une voie énergétiquement économe pour élaborer de nouvelles formulations de produits céréaliers. 17. Convention d'affaires des procédés industriels et services destinés à l'ensemble des acteurs du secteur agroalimentaire - ProFood 2010