1,721,035 research outputs found

    Using spacer layers to control metal and semiconductor absorption in ultrathin solar cells with plasmonic substrates

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    We systematically explore the performance of ultrathin amorphous silicon solar cells integrated on plasmonic substrates of several different morphologies. Angle-resolved reflectance, external quantum efficiency measurements, and finite-difference time-domain simulations highlight the importance of the spacer layer in determining the mode profiles to which light can couple. Coupling mechanisms are found to strongly differ between periodic silver nanovoid arrays and randomly textured silver substrates. Tailoring the spacer thickness leads to 50% higher quantum efficiencies and short-circuit current densities by tuning the coupling between the near-field and trapped modes with enhanced optical path lengths. The balance of absorption for the plasmonic near field at the metal/semiconductor interface is analytically derived for a broad range of leading photovoltaic materials. This yields key design principles for plasmonic thin-film solar cells, predicting strong near-field enhancement only for CdTe, CuInGaSe2, and organic polymer devices

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed

    Variations on the Author

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    “Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship

    Appropriate Similarity Measures for Author Cocitation Analysis

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    We provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis

    Dispelling the Myths Behind First-author Citation Counts

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    We conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more sophisticated methods

    Author Index

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    Vertical High-Voltage Transistors on Thick Silicon-on-Insulator [Elektronisk resurs]

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    More and more electronic products, like battery chargers and power supplies, as well as applications in telecommunications and automotive electronics are based on System-on-Chip solutions, where signal processing and power devices are integrated on the same chip. The integration of different functional units offers many advantages in terms of reliability, reduced power consumption, weight and space reduction, leading to products with better performance at a hopefully lower price. This thesis focuses on the integration of vertical high-voltage double-diffused MOS transistors (DMOSFETs) on Silicon-on-Insulator (SOI) substrates. MOSFETs possess a number of features which makes them indispensable for Power Integrated Circuits (PICs): high switching speed, high efficiency, and simple drive circuits. SOI substrates combined with trench technology is superior to traditional Junction Isolation (JI) techniques in terms of cross-talk and leakage currents. Vertical DMOS transistors on SOI have been manufactured and characterized, and an analytical model for their on-resistance is presented. A description of self-heating and operation at elevated temperatures is included. Furthermore, the switching dynamics of these components is investigated by means of device simulations with the result that the dissipated power during unclamped inductive switching tests is reduced substantially compared to bulk vertical DMOSFETs. A large number of defects is created in the device layer if the trenches are exposed to high temperatures during processing. A new fabrication process with back-end trench formation is introduced in order to minimize defect generation. In addition, a model for the capacitive coupling between trench-isolated structures is developed.</p

    koamabayili/VECTRON-author-checklist: VECTRON author checklist

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    We have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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