55 research outputs found

    Study on a compact and adaptable Thomson Spectrometer for laser-initiated 11B(p,α)8Be reactions and low-medium energy particle detection

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    Thomson Spectrometers are of primary importance in the discrimination of particles produced by laser-plasma interaction, according to their energy and charge-mass ratio. We describe here a detailed study on a set of Thomson Spectrometers, adaptable to different experimental situations, with the aim of being placed directly within the experimental chamber, rather than in additional extensions, in order to increase the solid angle of observation. These instruments are suitable for detection of low-medium energy particles and can be effectively employed in laser-plasma experiments of 11B(p,α)8Be fusion. They are provided with permanent magnets, have small dimensions and compact design. In these small configurations electric and magnetic fringing fields play a primary role for particle deflection, and their accurate characterization is required. It was accomplished by means of COMSOL electromagnetic solver coupled to an effective analytical model, very suitable for practical use of the spectrometers. Data from experimental measurements of the magnetic fields have been also used. We describe the application of the spectrometers to an experiment of laser-plasma interaction, coupled to Imaging Plate detectors. Data analysis for spectrum and yield of the detected radiation is discussed in detail. © 2016 ENEA

    Review of the late Quaternary stratigraphy of the northern Gulf of Cadiz continental margin:New insights into controlling factors and global implications

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    Over the past decades, the northern Gulf of Cadiz has been the focus of a wide range of late Quaternary seismic and sequence stratigraphic studies, either addressing the slope contourite depositional system (CDS), or the development of the continental shelf. Yet, high-resolution seismic data bridging between these domains and age information have remained sparse. This study, based on new high-resolution reflection seismic profiles calibrated to IODP Expedition 339 sites U1386/U1387, now presents an updated stratigraphic framework, that integrates (for the first time) the late Quaternary records of the northern Gulf of Cadiz middle slope to shelf off the Guadiana River. Seismic stratigraphic analysis of the stacking, depocenter distribution, stratal architecture and facies of the seismic (sub-)units reveals the influence of similar to 100 kyr sea-level variations paced by Milankovitch (eccentricity) cycles, tectonics (manifesting as two pulses of uplift and margin progradation), sediment supply and bottom current activity. This work furthermore contributes to the application and understanding of high-resolution, late Quaternary sequence stratigraphy. Firstly, the proposed sequence stratigraphic interpretation shows that adaptations to the basic models are required to integrate the shelf and slope record, and to account for the presence of a significant alongslope (bottom current-controlled) component. Secondly, the results confirm that the sequences are dominantly composed of regressive deposits, whereas the preservation of transgressive to highstand deposits is more irregular. Significantly, the common assumption that successive major glacial lowstands are consistently recorded as well-marked, shelf-wide erosional unconformities, is demonstrated to be occasionally invalid, as tectonics can obliterate this one-to-one relationship

    A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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    Approche économique de l'exploration des stockages souterrains de gaz en nappe aquifère Economic Approach to Exploration for Underground Gas Storage Facilities in Aquifers

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    Dans le cadre de la recherche des stockages souterrains de gaz, le Département Réservoirs Souterrains de Gaz de France est amené à établir un programme d'exploration destiné à sélectionner définitivement, et au moindre coût, les structures capables de satisfaire la demande. Cette sélection passe par une estimation des probabilités de rejet ou d'abandon affectant les différentes structures susceptibles de donner lieu à une exploration. Il faut ensuite constituer le programme d'exploration de chacun des sites retenus après cet examen; ce programme consiste en une liste d'opérations (forage, sismique, essai hydraulique, forage à faible profondeur etc. ) qui mettront le plus vite possible en évidence : - d'une part les défauts; - d'autre part les principales caractéristiques techniques de la structure étudiée. La règle est d'atteindre la décision sur la faisabilité du site au stockage avec le moindre coût d'exploration. Pour ce faire, une analyse détaillée des causes potentielles d'abandon (recensement des défauts) permet de choisir les opérations à effectuer, et d'associer à chacun des défauts recensés, l'opération ou l'ensemble d'opérations permettant de le détecter de façon certaine. Alors les estimateurs économiques tels que l'espérance de dépense, le risque financier, l'espérance de gain, sont calculés pour chacun des programmes, en vue de déterminer l'ordre d'exécution optimal des opérations. L'intérêt d'une telle approche, en ce qui concerne la réduction des dépenses d'exploration, est illustré par un exemple. <br> As part of its work concerning the search for underground gas storage sites, the Underground Storage Department of Gaz de France has established an exploration program for the definitive and lowcost selection of suitable geological structures. This selection involves estimating probabilities of rejecting or abandoning different structures liable to be targets for exploration. The exploration program for each of the sites chosen must then be drawn up. This program consists of a list of operations to be performed (drilling, seismic surveys, hydraulic tests, shallow drilling, etc. ) to reveal the following aspects as quickly as possible: (1) faults, and (2) the main technical features of the structure investigated. The goal is to reach a decision as to the feasibility of the site for storage at the lowest possible exploration cost. To do this, a detailed analysis of potential reasons for abandonment (study of fault) is made. The operations to be carried out are then chosen. Economic estimates, such as the expected expenditures, financial risk and gains hoped for are calculated for each program to determine the optimum order of execution for the operations. The advantage of such approach concerning the reducing of exploration expenditures is illustrated by an example. Cet article a fait l'objet d'une communication au 104e Congrès du Gaz, Strasbourg, 21-26 septembre 1987, organisé par l'Association Technique de l'Industrie du Gaz en France

    A multiphase multicomponent modeling approach of underground salt cavern storage

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    International audienceIn the current energy transition context, large-scale underground facilities, such as salt caverns, able to deliver high flow rates, represent the most promising viable massive energy storage system that can respond efficiently to the flexibility needs of the renewable energy.In order to predict the performances of these facilities, while ensuring a high safety level over long time periods, the reservoir behavior must be studied by higher accuracy approaches. Based on a multiphase multicomponent approach, a cavern thermodynamic model, that can be used in field applications, is derived for this purpose. Particular attention is given to salt caverns where the stored fluid can be in contact with the brine. All the balance equations that govern the well that connects the cavern to the ground surface and the surrounding formation are presented. An illustrative example, showing the necessity of taking into account the thermo-mechanical aspects when considering the cavern thermodynamic behavior under cyclic loading conditions, is also discussed
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