Guerre des courants

Résumé

thumb|Thomas Edison, inventeur et homme d'affaires américain, il était en faveur du développement d'un réseau électrique en courant continu. thumb|George Westinghouse, ingénieur et homme d'affaires américain, il a apporté son soutien financier au développement d'un réseau électrique en courant alternatif fonctionnel. thumb|Nikola Tesla, inventeur, physicien et ingénieur en électro-mécanique, il a été l'artisan du développement des réseaux en courant alternatif. La guerre des courants (parfois appelée bataille des courants) est une controverse technique et industrielle qui s'est déroulée aux États-Unis, à la fin des années 1890. Elle est centrée sur l'opposition entre Thomas Edison, partisan de l'utilisation du courant continu (en anglais DC, pour direct current) pour le transport et la distribution d'électricité, et George Westinghouse et Nikola Tesla, promoteurs de l'utilisation du courant alternatif (en anglais AC, pour alternating current). Contexte Dans les premières a

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https://fr.wikipedia.org/wiki/Guerre_des_courants

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Study of a Novel OCXO Characterization Based on Oven Supply Currents for Enhanced Holdover Compensation

Jean-Pierre Aubry, Marcel Baracchi Frei, Cyril Botteron, Pierre-André Farine, Elham Firouzi, Davide Manetti, Nicolas Charles Yves Voirol

2008

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Realization of high efficiency micromorph tandem silicon solar cells on glass and plastic substrates: Issues and potential

Christophe Ballif, Mathieu Gérard Boccard, Peter Cuony, Matthieu Despeisse, Andrea Feltrin, Franz-Josef Haug, Sylvain Nicolay, Martin Python

High conversion efficiency for (amorphous/microcrystalline) "micromorph" tandem solar cells requires both a dedicated light management, to keep the absorber layers as thin as possible, and optimized growth conditions of the microcrystalline silicon (μc-Si:H) material. Efficient light trapping is achieved here by use of textured front and back contacts as well as by implementing an intermediate reflecting layer (IRL) between the individual cells of the tandem. This paper discusses the latest developments of IRLs at IMT Neuchtel: SiOx based for micromorphs on glass and ZnO based IRLs for micromorphs on flexible substrates were successfully incorporated in micromorph tandem cells leading to high, matched, current above 13.8 mA/cm2 for pin tandems. In nip configuration, asymmetric intermediate reflectors were employed to achieve currents of up to 12.5 mA/cm2. On glass substrates, initial and stabilized efficiencies exceeding 13% and 11%, respectively, were thus obtained on 1 cm2 cells, while on plastic foils with imprinted gratings, 11.2% initial and 9.8% stable efficiency could be reached. Recent progress on the development of effective front and back contacts will be described as well. © 2010 Elsevier B.V. All rights reserved.

2011

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Prospects for the use of high-T-c superconductors in fusion magnets and options for their test in SULTAN

Pierluigi Bruzzone, Stephen Alfred March, Boris Stepanov, Davide Uglietti, Rainer Wesche

In the last few years, the critical current densities of long commercially available REBa2Cu3O7-x (RE-123, where RE represents Y or a rare earth element) coated conductors have reached values of 250 A/cm-width at 77K and zero applied field. Even higher values of 600 A/cm-w (77 K, B = 0) have been demonstrated in shorter lengths. The attractive features of the use of these high-T-c superconductors (HTS) are operation temperatures above 20K and/or magnetic fields higher than those envisaged for the ITER TF coils. Possible operation conditions for HTS fusion magnets have been studied taking into consideration the possible further improvements of RE-123 coated conductors. Investigations of stability and quench behavior indicate that stability is not a problem, whereas quench detection and protection need attention. Because of the high currents necessary for fusion magnets, many tapes need to be assembled into a transposed conductor. The qualification of HTS conductors for fusion magnets would require their test at magnetic fields of 11 land currents well above 10 kA. The possibilities to test straight HIS conductor samples in SULTAN have been considered. For a test at 4.5 K, only the development of a low resistance joint between the HTS conductor under test and the NbTi transformer of SULTAN would be necessary. Tests up to 20K would require that the HTS sample is connected with the NbTi transformer by a conduction-cooled HTS bus bar of large thermal resistance similar to the HIS module of a current lead. HIS conductor tests at temperatures around 50K would be possible with modified cryogenics. (C) 2013 Elsevier B.V. All rights reserved.

Elsevier Science Sa2013

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