1,721,038 research outputs found
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
Variations 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
Nd:YAG laser welding of fine sheet metal butt joints in AZ31 magnesium alloy
No full textMagnesium alloys have been used increasingly in various areas of industry, such as the automotive sector, electronic components. A reliable method for joining components produced with these materials will definitely allow for a wider use of these alloys. In this article, the laser welding process with an Nd:YAG laser using a maximum power of 2 kW was studied and reported. The effect of welding parameters, such as laser and welding, was analysed. Metal sheets of 1mm thickness in AZ31B magnesium alloy were butt-welded with helium and argon as shielding gas in the absence of filler material. The mechanical characteristics were measured during tensile tests, using digital image correlation (DIC) as a deformation measurement technique. After a preliminary experimental plan aimed at exploring the range of process parameters, the welding process was optimized using an approach based on the design of experiments (DoE). Consecutive experimental plans led to optimized butt joints, which, following a tensile test, showed a sound weld bead with fracturing in the base material. Local strain analysis by DIC highlighted different tensile behaviours, in terms of deformation of the weld bead, in the optimized butt joints with respect to those that were not optimized
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
Saldatura ibrida laser-arco della lega di titanio Ti6Al4V: caratterizzazione meccanica dei giunti e tolleranza al gap
No full textThe present research deals with the studies on mechanical characteristics of butt joint in Ti6A14V titanium alloy sheets of 3.0 mm thickness, comparing the welded joints obtained by laser beam welding without filler material and by laser-arc hybrid welding. These studies were performed by measuring Vickers hardness in the cross-sections obtained by welding. In particular the influence of the gap between the test sheets welded by laser CO2-MIG hybrid process has been analyzed. The morphological analysis of cross-section of welded joints obtained by different gaps has also been studied. Welded joints were characterized by tensile test and the deformation behaviour of welded joints by an optical measurement system of deformation based on the acquisition of stereoscopic images (ARAMIS 3D system). *** Nell’articolo sono riportati i risultati di un confronto tra le caratteristiche meccaniche di giunti testa a testa di lamiere in lega di titanio Ti6Al4V di spessore 3.0 mm, realizzati mediante saldatura con fascio laser senza materiale d’apporto e mediante saldatura ibrida laser-arco. Sono stati eseguiti rilievi di durezza Vickers nelle sezioni trasversali dei cordoni di saldatura ottenuti. In particolare è stata analizzata l’influenza del gap tra le amiere in prove di saldatura con tecnologia ibrida laser CO2-MIG. È stata eseguita l’analisi morfologica delle sezioni trasversali dei cordoni di saldatura ottenuti con diversi gap. I giunti saldati sono stati sottoposti a prove di trazione e il comportamento deformativo del giunto è stato analizzato tramite un sistema ottico di misura delle deformazioni basato sull’acquisizione stereoscopica delle immagini (sistema di analisi ARAMIS 3D)
Saldatura ibrida laser-arco della lega di titanio Ti6Al4V: caratterizzazione meccanica dei giunti e tolleranza al gap
No full textThe present research deals with the studies on mechanical characteristics of butt joint in Ti6A14V titanium alloy sheets of 3.0 mm thickness, comparing the welded joints obtained by laser beam welding without filler material and by laser-arc hybrid welding. These studies were performed by measuring Vickers hardness in the cross-sections obtained by welding. In particular the influence of the gap between the test sheets welded by laser CO2-MIG hybrid process has been analyzed. The morphological analysis of cross-section of welded joints obtained by different gaps has also been studied. Welded joints were characterized by tensile test and the deformation behaviour of welded joints by an optical measurement system of deformation based on the acquisition of stereoscopic images (ARAMIS 3D system). *** Nell’articolo sono riportati i risultati di un confronto tra le caratteristiche meccaniche di giunti testa a testa di lamiere in lega di titanio Ti6Al4V di spessore 3.0 mm, realizzati mediante saldatura con fascio laser senza materiale d’apporto e mediante saldatura ibrida laser-arco. Sono stati eseguiti rilievi di durezza Vickers nelle sezioni trasversali dei cordoni di saldatura ottenuti. In particolare è stata analizzata l’influenza del gap tra le amiere in prove di saldatura con tecnologia ibrida laser CO2-MIG. È stata eseguita l’analisi morfologica delle sezioni trasversali dei cordoni di saldatura ottenuti con diversi gap. I giunti saldati sono stati sottoposti a prove di trazione e il comportamento deformativo del giunto è stato analizzato tramite un sistema ottico di misura delle deformazioni basato sull’acquisizione stereoscopica delle immagini (sistema di analisi ARAMIS 3D)
Nd:YAG laser weldability and mechanical properties of AZ31 magnesium alloy butt joints
No full textLaser welding process using a Nd:YAG laser of maximum power of 2 kW was investigated and reported. Magnesium alloy AZ31 sheets with thickness of 3.3 mm have been butt welded with Helium and Argon used as shielding gases. The effect of processing parameters including laser power, welding speed, focal point position, nozzle configuration and protection gas flow was researched. Microstructure and mechanical properties of butt joints welded without filler were studied using optical microscopy, morphological analysis and mechanical tests (tensile, hardness). The first phase of experimental tests consisted in penetration tests (bead on plate) with the aim of identify the range of input parameters. In the second phase butt welding tests were performed in order to determine the optimal conditions. Tensile tests were realized using extensometers and an optical system based on digital image correlation techniques for acquisition and analysis of local deformation. Static tensile tests revealed an increase in the yield strength of all welded specimen in relation to the not welded material. Morphological analysis and mechanical characterization showed a threshold of heat input value below which, even when there is sufficient irradiance, the ultimate tensile strength and the elongation to fracture of the joint decade heavily. The local strain analysis revealed that the fracture occurs due to localization of deformation on weld bead as a result of defects on the surface of the bead. Metallographic analysis of cross-sections did not show defects like porosity, inclusions and cracks, within the weld bea
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