1,721,188 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Transverse distribution of the transport current density in (Bi, Pb)2223 tapes
No full textThe distribution of the critical transport current density, Jc, has been measured across the core thickness of silver sheathed (Bi, Pb)2223 tapes which contained silver addition of different particle sizes. We have found the Jc of tapes without silver addition and with 8 wt% silver addition of small particle size decreases continuously with distance from the core-sheath interface. The Jc of layers close to the silver sheath is up to four times higher than that of central layers, e.g. 3 × 104A cm?2 near the sheath and 7 × 103 Acm?2 in the centre at 77 K and self field. The tape with addition of 50 wt% 80 ?m silver particles shows a uniform Jc of about 2 × 104 A cm?2 throughout the core thickness. The V?I characteristics of the baser core of the tape without silver addition have also been measured in magnetic fields
The effect of sintering temperature on the crystal growth of the Bi-2223 phase in multifilamentary tape
No full textBi-2223 tapes with 37 filaments, Ag–Mg–Ni alloy outer sheath and pure Ag inner sheath were heat treated in 7.5% O2 at different temperatures for 40 h. XRD of etched samples for increasing sintering temperature from 798 to 847 °C showed an increase of eightfold in the absolute intensity of the Bi-2223 (0 0 10) peak, without substantial decrease in the intensity of the Bi-2212 (0 0 Image) peak. These changes were correlated with the amount of liquid phase obtained from the Bi-2201 (0 0 8) peak. Optical microscopy also suggested an important role of the liquid phase by revealing significant changes in the morphology of Bi-2223 grains with increasing sintering temperature
Reduction in secondary phases and increased transport I(c) of (Bi,Pb)2223/Ag tapes sintered with rapid heating rates
No full textIn a two-step heat treatment with one intermediate rolling the final transport critical current, (Ic at 77 K, self field, 1iV/cm), of 37 filament (Bi,Pb)2223/Ag tapes increases linearly with the heating ramp rate: 20 A to 40 A, (~20,000 Acm-2), for 20°C/hour to 400°C/hour. The principle benefit of the rapid ramp rate is likely to come from ramping fast though 800°C to 832°C in the 1st heat treatment. SEM and XRD analysis on the superconductor-Ag interface show a decrease in the amount of secondary phases, Cu2O, Bi2(Sr,Ca)2Cu1Ox, Bi(Sr,Ca)Ox, with increasing ramp rate and critical current
Variations on the Author
Get PDF“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
Ic and phase characteristics of (Bi,Pb)2223 tapes after 1 heat treatment in a temperature gradient under different oxygen partial pressures
No full textThe heat treatment of (Bi,Pb)2223 tapes in a furnace with a temperature gradient allows the study of many heat treatment temperatures at the same time. 20 cm lengths of tape were given a typical first heat treatment of a period of 40 hours in a ~1°C/cm temperature gradient under either 7.5% partial pressure O2, or air. The maximum amount of (Bi,Pb)2223 occurred in a temperature window, (⩽2% change in the phase composition) of about 7°C under 7.5% partial pressure and 2°C under air. The relationship between the phase composition and the transport current, Ic, for both atmospheres is investigate
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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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