1,720,963 research outputs found
Influenza del trattamento termico e delle caratteristiche microstrutturali sulla resilienza della lega di alluminio A356 colata in conchiglia
No full textIn questo studio sono presentati i risultati di una campagna di prove condotte al fine di valutare l’influenza della distanza interdendritica secondaria (SDAS) e del trattamento termico sulla resilienza di una lega d’alluminio con il 7% di silicio, utilizzata nella realizzazione di un componente motociclistico colato in conchiglia. Queste prove si inseriscono all’interno di un’estesa ricerca, volta a chiarire e ad approfondire la conoscenza sui parametri che influenzano la resilienza di leghe d’alluminio da fonderia, mediante l’utilizzo della prova di resilienza strumentata. La sperimentazione, condotta sul componente in esame, ha fatto registrare un infragilimento del materiale provocato dal trattamento termico T6 ed è stata individuata una correlazione inversa tra lo SDAS ed entrambe la forza di picco e l’energia assorbita durante l’urto. Infine, i provini prelevati dai componenti trattati termicamente hanno presentano curve forza-spostamento tipiche di un comportamento di transizione tra dominio duttile e dominio fragile, mentre per i provini non trattati termicamente le curve sono risultate tipiche di un comportamento duttile
Effect of eutectic modification and solidification rate on impact strength of A356 aluminum-silicon alloys
No full textThe impact energies of A356 aluminum-silicon
alloys have been measured using a
Charpy impact tester. The Charpy specimens
have been machined from cast plates with the
same geometry and produced in sand
moulds. Unmodified, sodium-modified and
strontium-modified castings have been tested.
In this paper, the effects of eutectic
modification and of the cooling rate on the
impact properties of A356 aluminum-silicon
alloys have been studied. When the value of
the cooling rate is the same, unmodified
samples show lower impact energies than
modified ones: the effect of eutectic
modification is emphasized in strontium modified
samples. Moreover, a finer
microstructure always corresponds to higher
impact strength and an inverse correlation
between impact energy and secondary
dendrite arm spacing (SDAS) has been
found. The fracture profile and surface of
cracked samples have been analyzed by
means of Optical and Scanning Electron
Microscopes, in order to investigate the effect
of eutectic silicon and intermetallic particles.
Numerical simulations have been carried out
to study the filling and the solidification
behavior of the sand cast plates under
different cooling conditions, in order to
predict the final microstructure and shrinkage
formation. A good correspondence between
SDAS values, calculated by means of
numerical simulations and measured with the
linear intercept method, has been found
Influenza dollo SDAS e del trattamento termico sulla resilienza di una lega di alluminio A356 colata in conchiglia
No full textVengono riportati i risultati di prove sperimetali condotte per valutare l'influenza dello SDAS (spaziatura interdendritica secondaria) e del trattamento termico, sulla resilienza di una alluminio con il 7% di silicio. La lega viene utilizzata nella realizzazione di un componente motociclistico (forcellone posteriore) colato con processo in conchiglia (gravity die casting)
The use of a collagenated porcine cortical lamina in the reconstruction of alveolar ridge defects : a clinical and histological study
No full textThe use of resorbable and non-resorbable membranes has been proposed to increase the hard tissue volume in deficient sites. For vertical GBR is necessary to use non-resorbable devices to maintain the volume. Collagenated porcine cortical barrier seems to have different clinical advantages, including: stability of the membrane; the plastic consistency; the absence of a second re-entry surgery for its removal; the quality of integration; decreasing the risk of infections in case of exposure. The purpose of this study was therefore to clinically and histologically evaluate the use of collagenated porcine bone lamina in case of horizontal and vertical bone augmentation procedures in conjunction with particulate porcine xenograft
Soft tissue enhancement combined with biologically oriented preparation technique (BOPT) to correct volumetric bone defects: a case report
No full textHorizontal bone defects are traditionally treated with bone augmentation techniques, before implants placement, to satisfy both aesthetic and functional demands of the patients. In the present case a limited horizontal bone resorption has been treated with soft tissues management associated at the concepts of BOPT technique in order to correct volumetric bone defects to achieve a proper ridge contour
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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