1,720,957 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
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
A novel technique for evaluating the degradation of engine components non-destructively
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Impedance spectroscopy (IS) was used to evaluate the microstructural changes of a thermally-grown oxide (TGO) layer on a nickel-based superalloy or bond coat, with or without a thermal barrier coating (TBC) system, at various temperatures. TBC is used for hot section parts of gas turbine engine, such as turbine blades and vanes. However, spallation of TBC can take place due to long-term operation at high temperature. The spallation is mainly caused by both microstructural changes and thermal stresses as a result of oxide layer (mainly alumina) formation and growth at the interface between the TBC and bond coat. The electrical resistance and capacitance of the oxide layer, formed from oxidation of IN738LC superalloy at high temperature, were obtained from fitting the results of the measured impedance diagrams based on an equivalent circuit model. The equivalent circuit model should represent the features of the oxide layer or the TBC system. The electrical resistance of the oxide layer increased with increasing oxidation time for samples exposed to air at 900°C. Similar results were obtained for the NiCrCoAIY bond coat samples and the TBC systems. The capacitance decreased with increasing thickness of the alumina layer. The activation energy of electrical conduction was used to characterise the alumina layer formed on the bond coat at 900°C, 1000°C and 1100°C. The activation energy values for the alumina layer, formed at various temperatures, decrease with increasing impurity or porosity. Changes in the electrical properties of TGOs are correlated with those in their microstructure and microchemistry. The degradation of a TBC can be identified, when the electrical resistance of the TGO decreases with
increasing oxidation time. The fast decrease in resistivity corresponds to the compositional change in the TGO from cc-Al2O3 to a mixture of a-Cr2O3 and (Ni or Co)(Cr or Al)2O4 spinel. The disappearance of a-A1203 in the TGO makes the scale non-protective and leads to cracks and spallation of TBCs. Non-destructive testing of the crack formation in a TBC system is essential for predicting the failure and lifetime of TBCs in service. IS was used to evaluate the crack formation in the TBC system due to thermal cycling. During the thermal cycling, cracks initiated and propagated along the interface between the TGO and the yttrium stabilised zirconia (YSZ), used as a TBC. This caused the spallation of the TBC eventually. The propagation of cracks at the interface of TGO/YSZ was found to contribute to an increase in the interfacial impedance. The interfacial area determines the interfacial resistance corresponding to the oxygen reaction. Therefore, the crack propagation induced an increase of the interfacial resistance, whereas the interfacial capacitance showed no trend in its alteration with the propagation of the cracks. As a result, the relaxation frequency of the interface moved towards a lower frequency during the propagation of the cracks. Therefore, impedance spectroscopy has been used to examine the crack formation in TBC system non-destructively. By using scanning electron microscopy and X-ray diffraction techniques, the composition and microstructure of the oxide scales were examined. It was found that their electrical properties were determined, not only by the microstructure of the oxide scales, but also by the composition of the oxide scales. By determining the relationship between the electrical properties, microstructure and composition of the oxide scales, IS could be used as a non-destructive technique for monitoring the oxidation of metallic alloys at high temperature in gas turbine engine components.This study is funded by the EPSRC and Alstom gas turbine Ltd
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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