195 research outputs found

    Relations entre les entreprises et la recherche publique : lever des obstacles Ă  l\u27innovation en France (Les)

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    Des relations étroites entre les entreprises qui opèrent près des deux tiers de la R&D française et les établissements publics de recherche constituent un moteur puissant en matière d’innovation. Néanmoins, malgré différentes actions de l’État en ce sens, elles apparaissent moins intenses en France que dans nombre de grands pays industriels. En s’appuyant sur la perception et les attentes d’un échantillon d’entreprises nationales ainsi que l’analyse de politiques publiques et d’outils développés en matière de recherche partenariale par des acteurs étrangers, une série de propositions visant à accroître et améliorer ces relations essentielles est présentée. Elle concerne le pilotage étatique des politiques publiques liées à l’innovation ainsi que les dispositifs incitatifs associés, le pilotage des politiques locales des établissements publics et des structures dédiées à la recherche partenariale, des mesures et dispositifs destinés à développer la mise en relation, accélérer la mise en oeuvre des partenariats et mobiliser les ressources humaines nécessaires

    Réfrigération magnétique Etat de l'art et développements récents

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    La réfrigération magnétique, basée sur l'effetmagnétocalorique, est une thématique relativement récente etprometteuse devant permettre de réaliser des systèmes moinsénergivores que la technologie conventionnelle et sans impact surl'environnement. Pluridisciplinaire, elle implique de maîtrisertoute une filière, du matériau à l'application et de lever desverrous scientifiques et technologiques. L'article fait un état del'art, discute des derniers travaux réalisés, et illustre lesproblèmes soulevés en particulier dans le domaine thermique ens'appuyant sur l'expérience acquise au G2Elab.</p

    Review on the developments of active magnetic regenerator refrigerators – Evaluated by performance

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    © 2020 Magnetic/magnetocaloric refrigeration is an energy-efficient and environmentally safer cooling technology with the potential to be an alternative to conventional vapor compression systems in the future. Magnetocaloric effect (MCE) is a measure of relative temperature rise/drop of certain ferromagnetic materials upon the application/removal of a magnetic field. The technology uses MCE of some materials such as Gd to produce temperature difference/span relative to the ambient via a four-stage regenerative cycle known as active magnetic regenerative (AMR) cycle. Research in this area has been thriving especially during the last two decades focussing on different aspects of technology such as materials, magnetic field sources, and system design. On the system design, studies investigating the effect of different magnetic, thermal-hydraulic, and geometric parameters on the performance have been found in the literature. The present work offers a chronological review and comparison of recent advances in AMR refrigerators. Findings and results reported in the literature are compared in terms of magnetocaloric materials, geometric parameters (such as regenerator geometry); operating parameters e.g. cycle frequency, utilization, heat transfer fluid, heat rejection temperature, and cooling load, etc. Besides, performance indicators such as no-load temperature span, cooling capacity, and/or system coefficient of performance have been considered. Parametric sensitivity and performance trends have been identified and discussed. Major barriers to achieving system peak performance and hence the marketability of the technology are also highlighted

    Thermocapillary pumping of discrete drops in microfabricated analysis devices

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    A nonmechanical pumping mechanism, thermocapillary pumping (TCP), is described for moving nanoliter- and picoliter-sized drops of liquid within microfabricated flow channels. In TCP, one end of a single drop is heated to create a surface tension difference between the ends of the drop. The induced surface tension difference causes a capillary pressure difference between the two drop ends and results in drop motion. TCP velocities of up to 20 mm/min were measured for several liquids at temperature differences between 10 and 70°C. An expression developed for TCP velocity yields predictions that agree with experimental velocities within corresponding uncertainty limits. Several techniques for assisting TCP are also suggested when contact angle hysteresis, the major factor limiting TCP velocities, is too large. These techniques include using surface treatments to reduce the contact angle hysteresis, converging channels to offset hysteresis, or an applied pressure to assist in movement.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34237/1/690450215_ftp.pd
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