1,720,956 research outputs found
Line bending of Al2O3 coated and uncoated aluminium thin sheets
No full textA novel 'hybrid' forming process, consisting of a fluidized bed (FB) pre-treatment to coat with Al2O3 and pre-curve aluminium thin sheets and of a diode laser forming to perform the proper line bending of FB pre-treated sheets, is defined and investigated in this paper. A comparison with the diode laser forming of untreated aluminium thin sheets is also carried out. An experimental investigation is performed varying, in the laser forming process, output power, scan speed and number of passes and, in the 'hybrid' process, besides the laser parameters, even the treatment time in the FB system. Consistent trends of bending angles according to laser operative parameters are achieved for both the forming processes. A significant saving of laser power necessary to form the specimens, an increase in maximum angles achievable as well as an improvement of aesthetic aspect of the final products characterize the 'hybrid' forming process, if compared with the laser forming process. As a result of dissimilar forming technologies, completely different bending mechanisms are highlighted, with the 'hybrid' forming giving rise to an unexpected inversion in bending direction. Finally, the opportunity for further applications of the 'hybrid' technology is also discussed, stating the basis for a wider industrial diffusion of the non-conventional forming technologies even for the manufacturing of basic commodities. (c) 2005 Elsevier B.V. All rights reserved
Heat affected zone induced by laser forming
No full textLaser forming induces mechanical and structural modifications around the Laser Scanning Path. Various conventional methods are currently available to estimate properties of materials like X-ray and neutron diffraction, strain/curvature measurement, hole drilling, layer removal, chemical etching, etc. but their use is severely restricted due to measurement accuracy, applicability to different materials and geometrical configurations. An application of an experimental method to estimate mechanical properties associated with laser forming of metallic sheets is proposed. This method is based on an instrumented indentation technique which offers a more flexible tool to measure mechanical properties of Heat Affected Zone. The main advantage of this technique consists of testing complex geometric forms with a cheap system able to be used for on-line implementation. The experimental validation of the method was performed calibrating the procedure by using several indentation tests in standard condition. A full map of mechanical properties was subsequently traced employing systematic investigations focused on specimens zone closer to the laser heated scanning path
Local mechanical and morphological characterization of FSW butt joints
No full textIn this paper the results of an experimental investigation into the local mechanical and morphological characterization of AA6082-T6 friction stir-welded (FSW) butt joints are illustrated. The softening effects of the welding process are highlighted through the use of micro-indentation tests on the top surface of the specimens. The effect of post-welding heat treatments was investigated, als
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
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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