1,720,965 research outputs found
Subgap Time of Flight as a defect spectroscopy: application to CdTe:Cl radiation detectors
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NUMERICAL SIMULATION OF CSP BASED ON NANORECTENNA TECHNOLOGY
No full textConcentrated solar power (CSP) plants are one of several renewable energy technologies with significant potential to meet a part of our future energy demand. By now, CSP systems are used to supply photovoltaic or thermal power plant, but results on nanorectennas suggest the possibility to use this technology for direct energy conversion of solar radiation into electricity. A rectenna is a rectifying antenna that can be used to directly convert wave energy into DC electricity. Experiences in microwave applications have shown energy conversion efficiency in the order of 85%, and recently empirical tests have demonstrated that this technology can be used up to the infrared wavelength. The present paper, together with first preliminary results on the fabrication of the rectifier (the key element of a rectenna) and its electrical behavior, proposes the numerical simulation of a new CSP system where a receiver, heated by concentrated solar radiation, reemits infrared energy on the nanorectenna, which converts the incoming energy into electricity. In this way the receiver plays the role of a sunlight radiation converter to infrared energy.
The numerical simulation of the system consists of two steps. The first is a ray-tracing model to calculate the concentrator optical efficiency and the energy distribution on the focusing area of the parabolic mirror. The second step consists in the receiver temperature calculation as function of the incident solar radiation. The numerical procedure allows the calculation of the concentrator/receiver assembly performance which returns the energy incident on the nanorectenna as a function of external environmental conditions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Structural, morphological and chemical properties of Cu/TiN versus Cu thin layers for HEMT backside metallization
No full textVariations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
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