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L’objet de ce document est de proposer une synthèse ainsi que les perspectives de mes activités de recherche depuis 2007 à MINES ParisTech. Cette recherche est bien sûr le fruit d’un travail collectif mené par l’équipe dont j’ai actuellement la responsabilité. Mon apport scientifique dans ce groupe réside essentiellement dans l’aide à la formalisation mathématique des problèmes et à leurs résolutions au moyen d’algorithmes mettant en oeuvre le traitement d’image, du signal, l’analyse statistique ou, de manière générale, les mathématiques appliquées. J’y apporte également mes connaissances dans la mesure du rayonnement par des instruments de mesures in-situ acquises ces dernières années.

Solar irradiance and ancillary meteorological data are needed for solar resource assessment. Accurate measurements are required for comparison and adjustment of long‐term satellite data. Furthermore, reliable irradiance measurements are needed to validate Direct Normal Irradiance (DNI) forecasting methods. Starting in 2010, ten meteorological stations have been installed in the Middle East and Northern Africa (MENA) within the enerMENA project

La connaissance des propriétés thermodynamiques des minéraux argileux représente un enjeu important pour la mise en oeuvre et la sécurité à long terme des installations de stockage sous-terrain, pour le stockage de déchets nucléaire, de CO2 ou de toute autre substance dangereuse. Ces propriétés, issues pour la plupart d'expériences de mise à l'équilibre plus ou moins bien contrôlées ou de méthodes d'estimation souffrant d'un déficit de données pour leur calibration, étaient considérées comme mal définies. Afin de répondre à ce manque de connaissance, un programme spécifique a été mis en place. Ce programme, baptisé Thermochimie, a été initié et conduit avec le soutien de l'ANDRA. Il vise à compléter les bases de données thermodynamiques nécessaires aux calculs géochimiques, vis-à-vis des propriétés de ces minéraux argileux.

International audience; In the framework of geological disposal of radioactive waste, cement materials are foreseen to be used in the mechanical stability of the installations and to limit radionuclide transfer through the rock formation. In order to fill these requirements, the behavior of various concrete formulations is currently studied. In this context, low pH cementitious materials are considered as alternatives to classical high performance concretes in order to minimize chemical interactions at the interfaces between cement materials and the clay surrounding rock formations and/or engineered clay materials. The additive of supplementary cementitious materials such as blastfurnace slag and fly ash induces pozzolanic reactions with the precipitation of low Ca/Si (C/S) ratio of calcium silicate hydrates (C-S-H) to reach a lower equilibrium pH of the pore solution (pH ~10).It follows that the control of the pH will be governed by the C-S-H with lower C/S ratio. However, if in Ordinary Portland Cement (OPC) and/or standard concrete formulations the hydration products are well characterized with well constrained kinetic/thermodynamic models; for low pH formulation, the mineralogical control of elements in solution have to be discussed, if we consider that concentrations of elements in solution like Aluminum and magnesium are higher than for OPC. In particular for the hydration of MgO, which is mainly introduced by the BFS, Zhang, Cheeseman and Vandeperre have mentioned the precipitation of brucite (MgOH2) which reacted with the silica fume to produce a magnesium silicate hydrate (M-S-H). The calculated pH in equilibrium with this mineralogical assemblage is around 10.5 and satisfies the requirement of low pH condition.The occurrence of M-S-H has been mentioned in many environments, and was described as low crystalline phases according to the low intensity and broad peaks signals. Despite this abundance of M-S-H evidences and characterizations, the structure of M-S-H is not well known. Some authors have tried to explain the precipitation of such Mg-silicate hydrates according to Ca/Mg isomorphic substitution in the calcium silicate hydrates (C-S-H). The present study aims at determining this structure, to define their nature (cement phase or phyllosilicate). Two low temperature synthesis of M-S-H with a Mg/Si ratio of 0.6 and 1.2, close to the talc composition (Mg3Si4O10OH2) and consistent to the Ca/Si of the C-S-H phases. Crystal chemistry of M-S-H was determined by combining TGA, electron probe micro-analysis (EPMA), TEM, NMR and powder X-raydiffraction. Characterizations of these poorly crystalline Mg-silicates reveal a 2:1 magnesium phyllosilicate-like structure with short range stacking order, described as a talc-like structure. All the talc structure crystallographic evidences described in previous studies are in agreement with the characterization of the talc synthesis performed for short synthesis time. In that case, the M-S-H particles are displaying a low cristallinity and a small size. XRD patterns were successfully modeled according the modeling approach developed by, thus providing meaningful and accurate structural information, including structure defects, despite the weak modulation of the profiles. A full structure model is thus proposed for M-S-H.

International audience; Nuclear waste repositories will use a significant quantity of cement: for the construction of accessdrifts, disposal cells and concrete plugs, and as containment material for low- to intermediate-levelwaste. Several European countries have chosen claystone formations as possible host rocks (Landais,2006). Numerous cement/clay interfaces will thus be present in a radioactive-waste repository.Due to contrasting geochemical conditions (including Eh, pH, solution composition), these interfacesare subjected to steep concentration gradients and are highly reactive. Predicting long-term changes(1,000 to 100,000 years) in these cementitious and clayey materials is thus crucial for assessing thebehaviour of such infrastructures. Experiments cannot provide sufficiently reliable information oversuch long time scale. Although natural and archaeological analogues can be very helpful, modelling isthe unique tool to analyse and test different evolution scenarios. In order to build a better confidence insuch calculations, it is of paramount importance to demonstrate that the results obtained are notdependent on the choice of the numerical reactive transport code to perform the simulation. In order toaddress this issue, a benchmark problem, divided into three steps with increasing geochemicalrefinement, has been set up (Marty et al., submitted).In all cases, the solutes transport across the interface between clayey host rock and concrete isdiffusion driven and a 1D radial geometry and isothermal conditions (25°C) have been bothconsidered. Both materials are full saturated. The first step of the benchmark only considers porewatersolutions and the clayed host rock which is only modelled by an exchanger. The second stepintroduces the full mineralogy for both the concrete and the claystone considering slow kinetics ratesfor mineral dissolution-precipitation reactions, whereas the third one focuses on fast reaction rates.Seven international teams have been involved in this benchmarking exercise. All reactive transportcodes used (TOUGHREACT, PHREEQC with two different ways of handling transport,CRUNCHFLOW, HYTEC, ORCHESTRA, MIN3P-THCm) gave very similar patterns in terms ofpredicted solute concentrations and of minerals distribution evolution (Fig. 1). The benchmarkingexercise demonstrates that reactive transport tools have reached such a level of maturity as to beconfidently used in support of long-term performance assessments.

This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications; This report presents detailed information about solar resource data and the resulting data products needed for each stage of a solar energy project, from initial site selection to systems operations. It also contains a summary of solar forecasting and its development throughout the last few years. The U.S. Department of Energy's Solar Energy Technologies Office, project developers, engineering procurement construction firms, utility companies, system operators, energy suppliers, financial investors, and others involved in solar energy systems planning and development will find this handbook to be a valuable resource for the collection and interpretation of solar resource data. This handbook is expected to be used as a reference during each project stage.

International audience; Let G be a real Lie group with finitely many connected components and let Γ be a cocompact subgroup of G. We define the transfer from Γ to G in the homological and cohomological theory of differentiable modules and we show that the Poincaré duality identifies homological restriction and cohomological transfer by proving a transfer formula.

International audience; Ancient cities show us an unprecedented wealth of monuments. Despite many monuments still standing, few are still their marble decoration in situ. In contrast, the churches of St. Sophia and St. Saviour in Constantinople show a strong taste of the Byzantines for architectural decorations in decoratives stones, taste that we can observe today. This continuity between this interest to decorate monuments from ancient times and medieval times was often observed. However, a clear break between the two empires should be mentioned. It results in the loss of certain decorative rocks, in favour of new. The study of some cities should be an opportunity to highlight the break and hypothesis will be advanced to explain that. At last, use of marble so-called “Grand Antique des Pyrénées” in these two churches in Constantinople will be discussed.; Les villes antiques témoignent d'une richesse édilitaire sans précédent. Malgré de nombreux monuments encore en élévation, rares sont ceux dont les placages de marbres sont encore visible in situ. A contrario, les églises de Sainte-Sophie et du Saint-Sauveur à Constantinople témoignent d'un goût affirmé des Byzantins pour les décorations architecturales en pierres marbrières, que l'on peut encore observer aujourd'hui. Cette continuité de l'intérêt pour décorer les monuments entre les périodes antique et médiévale a souvent été mentionnée. Cependant, une rupture nette entre les deux empires doit être soulignée. Elle se traduit par la disparition de certaines roches décoratives, au profit de nouvelles. L'étude de quelques cités doit être l'occasion de mettre en avant cette rupture. L'utilisation du Grand Antique des Pyrénées au sein de ces deux monuments constantinopolitains est en cela exemplaire.

International audience; no abstract

International audience; The uncertainty of broadband shortwave radiation monitoring is determined for direct, diffuse, and global irradiance for measurements obtained at the Payerne (Switzerland) station of the Baseline Surface Radiation Network (BSRN). The uncertainty estimates include sources that reflect realistic long-term operation conditions. The uncertainties are derived using the methodology specified by the "Guide to the expression of uncertainty in measurement." The differences between redundant determinations of direct, diffuse, and global irradiance are analyzed and are shown to be compatible with the uncertainties. In addition, the signatures of some uncertainty sources are sought within the error statistics to find out if corrections can be applied and what their magnitude is. The global and diffuse irradiance uncertainties range from 1.8% to 2.4% without correction and are less than 1.8% with corrections. These uncertainties are close to or satisfy the BSRN targets for large signals (global: 1000 W m À2 , diffuse: 500 W m-2). For small signals (50 W m-2), the targets are not achieved, mainly as a result of uncertainties associated with the data acquisition electronics (DAQ). The direct irradiance uncertainty is ~1.5%, 3 times larger than the BSRN uncertainty target. An accuracy gain can also be achieved at the DAQ level, but even without considering the DAQ uncertainty, the target is exceeded by a factor of about 2. The direct irradiance uncertainty remains ~1% even using an absolute cavity radiometer as transfer standard for correcting the pyrheliometer sensitivity. Thus, the direct irradiance accuracy target of 0.5% is probably not achievable with the best commercially available technology.