73,288 research outputs found

    Summary of the high-efficiency crystalline solar cell research forum

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    An outline is given listing the speeches given in each session and the pertinent points is some speeches. There were six session, besides the overview session they were: (1) high efficiency concepts; (2) surface/interface effects; (3) bulk effects; (4) modeling; and (5) high efficiency device processing. Besides the emphasis placed on increasing efficiency of energy conversion, a great amount of discussion was spent on ways to reduce recombination and reducing surface defects

    Taking Back What’s Theirs: The Recess Appointments Clause, Pro Forma Sessions, and a Political Tug-of-War

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    This Note surveys the current landscape of the Recess Appointments Clause. With the recent recess appointments of Richard Cordray to direct the Consumer Financial Protection Bureau (CFPB) and three other individuals to join the National Labor Relations Board (NLRB), came an influx of old—and new—controversy over the President’s recess appointment authority. This Note explores interpretational issues that have surrounded the Clause since its inception, as well as novel issues that have arisen with the Congress’s use of pro forma sessions in an attempt to block recess appointments and derail the executive’s agenda. The conflict over control of the appointments process is at its peak, as exemplified by the current litigation seeking to invalidate President Obama’s most recent recess appointments. This Note examines the varied interpretations of the Clause, the current litigation and potential dispositions, the increasing congressional trend of using the appointments process as an obstructionist device, and the possible state of both the CFPB and the Recess Appointments Clause after litigation. Ultimately, this piece proposes a modified functionalist standard by which the validity of recess appointments should be judged. That is, if the Senate is in a truly functional recess for a period of longer than three days, then the President should be able to make a valid recess appointment. Additionally, this three-day rule can be broken in the event of an emergency that renders the Senate unable to advise and consent to a nominee at a time when a recess appointment is necessary for the uninterrupted functioning of the government

    Classical information capacity of a class of quantum channels

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    We consider the additivity of the minimal output entropy and the classical information capacity of a class of quantum channels. For this class of channels the norm of the output is maximized for the output being a normalized projection. We prove the additivity of the minimal output Renyi entropies with entropic parameters contained in [0, 2], generalizing an argument by Alicki and Fannes, and present a number of examples in detail. In order to relate these results to the classical information capacity, we introduce a weak form of covariance of a channel. We then identify several instances of weakly covariant channels for which we can infer the additivity of the classical information capacity. Both additivity results apply to the case of an arbitrary number of different channels. Finally, we relate the obtained results to instances of bi-partite quantum states for which the entanglement cost can be calculated.Comment: 14 pages, RevTeX (replaced with published version

    Silicon solar cell efficiency improvement: Status and outlook

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    Efficiency and operating life is an economic attribute in silicon solar cells application. The efficiency improvements made during the 30 year existence of the silicon solar cells, from about 6% efficiency at the beginning to 19% in the most recent experimental cells is illustrated. In the more stationary periods, the effort was oriented towards improving radiation resistance and yields on the production lines, while, in other periods, the emphasis was on reaching new levels of efficiency through better cell design and improved material processing. First results were forthcoming from the recent efforts. Considerably more efficiency advancement in silicon solar cells is expected, and the anticipated attainment of efficiencies significantly above 20% is discussed. Major advances in material processing and in the resulting material perfection are required

    Research possibilities? No! Needs for research to make PV solar energy utilization broadly competitive

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    The historical progression of efficiency improvements, cost reductions, and performance improvements in modules and photovoltaic systems are described. The potential for future improvements in photovoltaic device efficiencies and cost reductions continues as device concepts, designs, processes, and automated production capabilities mature. Additional step-function improvements can be made as today's simpler devices are replaced by more sophisticated devices

    Updating the limit efficiency of silicon solar cells

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    Evaluation of the limit efficiency based on the simplest, most basic mathematical method that is appropriate for the conditions imposed by the cell model is discussed. The methodology, the solar cell structure, and the selection of the material parameters used in the evaluation are described. The results are discussed including a set of design goals derived from the limit efficiency

    Analysis and evaluation in the production process and equipment area of the low-cost solar array project

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    It was found that the Solarex metallization design and process selection should be modified to yield substantially higher output of the 10 cm x 10 cm cells, while the Westinghouse design is extremely close to the optimum. In addition, further attention to the Solarex pn junction and base high/low junction formation processes could be beneficial. For the future efficiency improvement, it was found that refinement of the various minority carrier lifetime measurement methods is needed, as well as considerably increased sophistication in the interpretation of the results of these methods. In addition, it was determined that further experimental investigation of the Auger lifetime is needed, to conclusively determine the Auger coefficients for the direct Auger recombination at high majority carrier concentrations
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