1,721,024 research outputs found
GETTI IN LEGA DI MAGNESIO PRESSOCOLATI: RASSEGNA DI ESEMPI INDUSTRIALI
No full textDal punto di vista tecnologico, sono svariati i vantaggi che il magnesio e le sue leghe possono assicurare:
• densità più bassa rispetto a tutti gli altri materiali metallici da costruzione;
• alta resistenza specifica;
• buona capacità di assorbimento degli urti;
• buona colabilità, appropriata per la colata ad alta pressione;
• buona lavorabilità alle macchine utensili con alte velocità di taglio;
• buona saldabilità in atmosfera controllata;
• buona resistenza a corrosione (se si impiega magnesio ad alto grado di purezza);
• facile reperibilità;
• caratteristiche complessivamente migliori rispetto ai materiali polimerici.
Il lavoro presenta una rassegna delle applicazioni delle leghe di magnesio per la realizzazione di componenti pressocolati
PROCESSING AND MECHANICAL PROPERTIES OF DIECAST AM50 ALLOY
No full textThe interest on Magnesium alloys for diecast components is continuously growing due to the unique combination of excellent castability and lightweigh properties. A wide range of applications can be found in various engineering fields, with particular regard to the automotive industry. A key-point, for this kind of applications, is certainly the achievement of a reliable mechanical behaviour, which is the direct consequence of the microstructure resulting from processing stages (filling of die, solidification and cooling, possible heat treatment). This paper presents the microstructural and mechanical properties “mapping” of diecast AM60B alloy, carried out on a “reference-casting”, properly developed for studying the effects of processing conditions and of geometrical features on the quality of the final product
Influence of Severe Plastic Deformations on Secondary Phase precipitation in an 6082 Al-Mg-Si alloy
Full text linkThe role of severe plastic deformation on the second-phase stability in a 6082 Al-Mg-Si alloy was
studied using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) techniques.
The alloy was fully annealed prior to undergoing up to six equal channel angular pressing (ECAP)
passes using route C. The Orowan strengthening mechanism was calculated on the basis of TEM inspections
for the two hardening second-phase precipitates: Mg2Si and Si. The former had a major tendency
to be cut and fragmented by dislocations, while in the latter, a dissolution process was induced by severe
plastic deformation. Accordingly, the second-phase Si particles became progressively less effective with
increasing deformation (i.e., additional ECAP passes). The increase in hardness with the ECAP passes
was mostly due to the grain refining mechanism and to dislocation tangles within the newly formed
grains. The expected, though if limited, contribution of second-phase hardening was prevalently accounted
for by the Mg2Si particles
Esperienze di produzione mediante tecnica Equal Channel Angular Pressing e proprietà di leghe di alluminio massive a struttura ultrafine. La metallurgia italiana
No full text
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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