A framework for parameter estimation using sharp-interface seawater intrusion models

Funding : This work was supported by Quebec’s Ministère de l'Environnement et de la Lutte contre les changements climatiques (MELCC) [project « Acquisition de connaissances sur les eaux souterraines dans la région des Îles-de-la-Madeleine » (Groundwater characterization project in the Magdalen Islands region)]; and the Fonds québécois de la recherche sur la nature et les technologies (FRQNT) [International internship program accessed through CentrEau, the Quebec Water Research Center]. The authors would like to thank the Municipality of Les Îles-de-la-Madeleine for providing pumping datasets and information on current and historical groundwater management. They would also like to thank the team at Université Laval working on the Magdalen Islands project, for their help acquiring datasets and for field logistics, John Molson, for proofreading, and finally the two anonymous reviewers for their valuable comments. The authors would also like to thank Vincent Post for discussions on deep open boreholes, and Francesca Lotti and John Doherty for discussions on seawater intrusion modeling and data assimilation. J-C Comte and O Banton acknowledge the financial support from the Fonds d'Action Québécois pour le Développement Durable for the ERT data collection, undertaken as part of the Madelin'Eau consortium (Ageos-Enviro'Puits-Hydriad), and further thank the Municipality of Les Îles-de-la-Madeleine for fieldwork logistical and technical support.Peer reviewedproo

The Athena X-ray Integral Field Unit (X-IFU)

The X-ray Integral Field Unit (X-IFU) is the high resolution X-ray spectrometer of the ESA Athena X-ray observatory. Over a field of view of 5' equivalent diameter, it will deliver X-ray spectra from 0.2 to 12 keV with a spectral resolution of 2.5 eV up to 7 keV on similar to 5 '' pixels. The X-IFU is based on a large format array of super-conducting molybdenum-gold Transition Edge Sensors cooled at similar to 90 mK, each coupled with an absorber made of gold and bismuth with a pitch of 249 mu m. A cryogenic anti-coincidence detector located underneath the prime TES array enables the non X-ray background to be reduced. A bath temperature of similar to 50 mK is obtained by a series of mechanical coolers combining 15K Pulse Tubes, 4K and 2K Joule-Thomson coolers which pre-cool a sub Kelvin cooler made of a He-3 sorption cooler coupled with an Adiabatic Demagnetization Refrigerator. Frequency domain multiplexing enables to read out 40 pixels in one single channel. A photon interacting with an absorber leads to a current pulse, amplified by the readout electronics and whose shape is reconstructed on board to recover its energy with high accuracy. The defocusing capability offered by the Athena movable mirror assembly enables the X-IFU to observe the brightest X-ray sources of the sky (up to Crab-like intensities) by spreading the telescope point spread function over hundreds of pixels. Thus the X-IFU delivers low pile-up, high throughput (> 50%), and typically 10 eV spectral resolution at 1 Crab intensities, i.e. a factor of 10 or more better than Silicon based X-ray detectors. In this paper, the current X-IFU baseline is presented, together with an assessment of its anticipated performance in terms of spectral resolution, background, and count rate capability. The X-IFU baseline configuration will be subject to a preliminary requirement review that is scheduled at the end of 2018. The X-IFU will be provided by an international consortium led by France, the Netherlands and Italy, with further ESA member state contributions from Belgium, Czech Republic, Finland, Germany, Ireland, Poland, Spain, Switzerland and contributions from Japan and the United States.Peer reviewe

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over a hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. The X-IFU will be provided by an international consortium led by France, The Netherlands and Italy, with ESA member state contributions from Belgium, Czech Republic, Finland, Germany, Poland, Spain, Switzerland, with additional contributions from the United States and Japan.The French contribution to X-IFU is funded by CNES, CNRS and CEA. This work has been also supported by ASI (Italian Space Agency) through the Contract 2019-27-HH.0, and by the ESA (European Space Agency) Core Technology Program (CTP) Contract No. 4000114932/15/NL/BW and the AREMBES - ESA CTP No.4000116655/16/NL/BW. This publication is part of grant RTI2018-096686-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. This publication is part of grant RTI2018-096686-B-C21 and PID2020-115325GB-C31 funded by MCIN/AEI/10.13039/501100011033

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. (abridged).Comment: 48 pages, 29 figures, Accepted for publication in Experimental Astronomy with minor editin

Etude de la reponse mecanique de copolymeres et de melanges biphases a base de polymethacrylate de methyle

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : TD 82179 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Influence de la structure d'électrocatalyseurs nanodispersés sur les réactions impliquées dans une pile à combustion directe de méthanol

Les PEMFC apparaissent aujourd'hui économiquement viables et l'utilisation du méthanol est intéressante en tant que combustible. Son oxydation électrochimique entraîne la formation d'une espèce poison, CO adsorbé, qui réduit les performances de la pile. Des catalyseurs anodiques ont été préparés par dépôt électrochimique ou spontané de Ru à la surface de nanoparticules de Pt. L'activité maximale pour l'oxydation du méthanol est obtenue pour des dépôts électrochimiques en raison de la présence d'oxydes de ruthénium non réductibles dans les dépôts spontanés. Deux types d'espèces CO adsorbé sont observées à la surface de l'électrode, un échange peut avoir lieu. La formation d'un alliage PtRu n'est pas une condition nécessaire à une électrooxidation du méthanol efficace. Les membranes de type NafionÒ, l'électrolyte solide, sont perméables au méthanol ce qui entraîne une dépolarisation de la cathode. Un effet de la taille des particules de Pt a été observé sur les cinétiques de réduction de l'oxygène. Les petites particules sont plus tolérantes à la présence de méthanol. Un alliage Pt:Cr est plus actif que le Pt pour la réduction de l'oxygène en présence ou non de méthanol.PEMFCs appear as economically viable and methanol utilization is a promising approach. Methanol oxidation leads to a poisoning intermediate, adsorbed CO, which dramatically reduces the PEMFC's performances. Methanol oxidation electrocatalysts were prepared from Ru electrochemical or spontaneous deposition on carbon-supported Pt nanoparticles. The maximum in electrocatalytic activity for methanol oxidation is observed with electrochemical deposits because of the presence of non-reducible ruthenium oxides in the spontaneous deposit. Two CO species are observed at the electrode surface, an exchange between these two CO species may occur. The formation of a PtRu alloy is not a required condition for efficient methanol electroxidation. The solid electrolyte being permeable to methanol, the cathode is depolarised. A particle-size effect on oxygen reduction reaction kinetics with or without methanol is observed. As particle size decreases, the catalysts are more methanol tolerant. Based on particle size considerations, Pt:Cr appears to be a more active catalyst than Pt for oxygen reduction in methanol-containing electrolyte.POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Electrooxidation of Carbon Monoxide at Ruthenium-Modified Platinum Nano-particles: Evidence for CO Surface Mobility

International audienceRu-modified Pt nanoparticle surfaces were prepared using Ru electrochemical or spontaneous deposition on commercial-grade carbon-supported Pt nanoparticles (Pt-Vulcan XC72, E-TEK). Evidence for CO mobility was provided by cyclic voltammetry and FTIR reflectance spectroscopy experiments in weakly specifically adsorbing electrolyte such as 0.1 M HClO4. Since the diffusion of CO is slow, a “two peak” voltammetric behavior was observed for 0 Ru -1, which is attributed to adsorbed CO on Ru sites. Exchange between CO species adsorbed on Ru and Pt sites was also observed along with a complete oxidation of a pre-adsorbed CO monolayer at a potential relevant for DMFC applications. These results confirm that the formation of a PtRu alloy is not a pre-requisite for obtaining CO-tolerant electrocatalysts

Micro solvation dynamics at the passage of conical intersections observed in argon clusters of excited tetrakis(dimethylamino) ethylene

International audienc

Dirty or Tidy ? Contrasting peraluminous granites in a collapsing Orogen: Examples from the French Massif Central

International audiencePost collisional collapse commonly enhances crustal melting. Such melting typically produces peraluminous granitic magmas. In the French Massif Central, a mid-crustal segment of the western Variscan belt, two large granitic bodies were produced during the collapse of the Variscan Belt. The St Sylvestre Leucogranitic Complex (SSyL) in the western part of the Massif Central and the Velay Migmatitic Complex (VMC) in the Eastern part. Although these two complexes are formed in similar geodynamic context they present meaningful petrological and geochemical differences. The VMC (~305 Ma) is clearly intrusive in migmatitic terranes. The migmatitic host recorded two successive melting events M3 (720 °C and 5kb) dated between 335 and 315 Ma and M4 (850°C and 4 kb) dated at 305 Ma. The compositions of the VMC are strictly H2O-undersaturated and ranges from leucogranitic to granodioritic. Three main successive granite types have been distinguished (1) A heterogeneous banded biotite granite, (2) A main biotite-cordierite granite, where cordierite can be prismatic, as cockade or pseudomorphic (3) a late magmatic with large K-feldspar phenocryst and prismatic cordierite. The compositions of the VMC granites are quite similar to typical Australian S-type granites in the sense that they also show a positive correlation between ferromagnesian abundance and aluminosity. The SSyL (~320 Ma) is intrusive in upper greenschist facies to upper amphibolite migmatitic metasediment and orthogneiss (~3kb). The compositional variety observed in the SSyL suggests a continuous trend from a moderately mafic, peraluminous magma (cd- and sill- granite) to a H2O saturated granite ("two-mica" granite) facies and finally to an extremely felsic, H2O-saturated magma. Three granitic units have been recognized in the SSyL: (1) the western "Brame Unit" composed of the less evolved cd- and sill- granite facies (2) the central "St Sylvestre Unit", composed mainly by U-rich two-mica granite, intruded by two synchronously emplaced fine grained granites to its western margin: "Fanay" (biotite dominant) and "Sagne" (Li-muscovite only) (3) the eastern "St Goussaud Unit" mostly composed of a muscovite-dominant leucogranite surrounded by Sn-W mineralization. The compositions in the SSyL have a weak ferromagnesian character, negatively correlated with aluminosity and are quite similar in composition to High Himalayan syn-collisionnal peraluminous granite (e.g. Manaslu) Compositional trend of the VMC granite can be easily mimicked by the addition of peritectic material (i.e. produced during incongruent biotite melting) to experimental melts produced through the melting of metasediments (Dirty). Compositions of the SSyL are similar to experimental melt only (Tidy). Such differences in composition could be the results of different processes: 1) Different melting reactions as a consequence of different conditions of melting (e.g. different source composition, temperature). 2) The peritectic phases remained "trapped" in the source during melt extraction due to the structuration of the source or a lower melt viscosity (e.g. higher F, Li, H2O contents). Interestingly, while within dirty granites, peritectic phase entrainment controls compositional variability, Tidy granites display original melt compositional variability as well as the potential effects of late magmatic processes