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Analisi sperimentale della resistenza a fatica di particolari costruttivi in lega leggera saldati
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Preliminary investigation by synchrotron radiation of small cracks and defects in AA FSW samples
No full textA very good definition of defects position and dimension in welded joints is desirable for application of fracture
mechanics techniques and improvement of industrial acceptability criteria. The aim of this paper is to illustrate the
preliminary results achieved in the investigation of defects in aluminum welded joints, using the phase contrast X-ray
imaging techniques available at the SYRMEP beamline of the Elettra synchrotron radiation facility. Both CCD and
high-resolution X-ray films were employed as detection systems.
Three sets of experiments have been performed so far. The aim of the first one was to investigate feasibility and to
optimize the experimental set-up. A good definition of artifact defects on joints, obtained by both conventional
welding techniques and Friction Stir Welding, was achieved. Successively, the investigation was restricted to joints
obtained by Friction Stir Welding, which is currently the most interesting technique also from an industrial point of
view. In the FSW samples prepared for the second experiment some original very small flaws were visible. The flaws
size, 100 microns or more, makes them hardly detectable by means of conventional control methods. Further
investigation of these small defects will provide a new unique insight on the defects that can be found in FSW
samples. During the third experiment, that has not been finished yet, both a long and a small crack could be detected
on the two sides of a notched sample. The images show that the crack propagates along several planes, a condition
that has not been deeply investigated in a quantitative way up to now and will be the object of further investigation
“ʻThis loose, drifting material of lifeʼ: Virginia Woolf between the Private and the Public”
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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
Defects influence on fatigue behaviour of laser welded joints
No full textThis work is aimed at the fatigue strength prediction of laser welded joints in aluminium alloy containing defects through the examination of location, size and shape of the weld defects. Some published documents give guidance for this kind of fatigue assessment, in particular the British Standard PD 6493 (1991) and a document by the International Institute of Welding on fatigue of welded components (1995). The assessment procedures was applied to two series of laser butt welded joints made of 5 mm thick 5083 H321 aluminium alloy plates. The two series were obtained by using different parameters in the welding procedure. Each set of parameters introduces a large amount of flaws in the weld bead. The fatigue behaviour was experimentally determined by means of pulsating tension tests. The application of the assessment procedure, as proposed in the published documents, led to unsatisfactory results due to the excessive dimensions of the final design flaw. Theoretical predictions compatible with the experimental results were obtained by modifying the criterion adopted to measure the flaw dimension
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