1,721,047 research outputs found
A scanner for in situ X-ray radiography of large paintings: the case of “Paolo and Francesca” by G. Previati
No full textA scanner for digital radiography of large paintings has been designed and developed, aimed to in situ performances. We report here the application to “Paolo and Francesca” (260×230cm2), masterpiece by the Italian divisionist painter Gaetano Previati (1909). The scanner has given the whole radiography in 1137 X-ray shots, which were corrected for X-ray inhomogeneities and finally processed, minimizing the visual impact of the frame structure. The original version of the painting has been brought to the light, and it appears to be a further step in the evolution of the theme frequently experienced by the artist
Analisi morfologica/strutturale di schiume polimeriche mediante micro-tomografia a raggi X e test meccanici in situ
Get PDFSchiume di materiale polimerico sono comunemente impiegate in numerose applicazioni e settori industriali. Grazie alle loro proprietà termiche e meccaniche e alla loro leggerezza (alto rapporto superficie/volume) esse sono largamente usate per realizzare materiali isolanti, strati protettivi in caso di urti, galleggianti, imbottiture per mobili e altro. Le loro proprietà non dipendono solo dalla composizione chimica del materiale di base, ma sono fortemente influenzate dalla struttura tridimensionale delle celle. La tomografia computerizzata a raggi X appare la tecnica d’indagine più adatta all’analisi delle schiume, per via delle note proprietà di penetrazione dei raggi X, capaci conseguentemente di fornire informazioni sia sulla struttura interna che sulla superficie degli oggetti esaminati. A differenza però delle schiume metalliche, nel caso di quelle polimeriche la ricostruzione dei dettagli strutturali più fini è ostacolata dal basso contrasto nelle immagini dovuto al debole assorbimento dei raggi X nel polimero; pertanto, la scelta delle condizioni sperimentali più appropriate è critica. Lo scopo di questo
rapporto tecnico è mostrare come sia stato possibile eseguire una completa analisi della microstruttura della schiuma esaminata, caratterizzando accuratamente la sua porosità interna, partendo dai dati tomografici, utilizzando sofisticate tecniche di elaborazione di immagini. Allo scopo è stato utilizzato il software di visualizzazione e analisi 3D Avizo Fire, insieme ad un software applicativo realizzato dagli autori. Inoltre, l’analisi tomografica è stata usata anche per valutare le proprietà meccaniche e strutturali delle schiume sottoposte a test di compressione in situ. Quest’ultimo tipo di analisi è stato possibile grazie a una cella di carico integrabile con lo scanner tomografico. Questo insieme strumentale costituisce una importante risorsa ENEA per l’analisi di oggetti aventi una complessa geometria interna
come le schiume del caso esaminato o parti finite realizzate mediante processi di fabbricazione additivi.Foams of polymeric material are commonly employed in different types of applications and industrial fields. Thanks to their thermal and mechanical properties and their lightness (high surface/volume ratio), they are widely used in the manufacture of insulating materials, absorbing layers for impact protection, floats, furnishings etc. Their properties strongly depend on the three-dimensional cell structure. X-ray computed tomography appears as the more suitable analysis technique to characterize the foams. In fact, thanks to the high depth of penetration of X-rays, it is able to provide complete information on the internal structure of the analyzed objects, as well as on their outer surfaces. Unlike metallic foams, however, the resolution of the reconstructed structural features is hampered by the weak X-ray absorption in the polymer, giving as a result low contrast images. For this reason, the fine tuning
of the experimental conditions is critical. The intent of this report is to show how it was possible to carry out a thorough microstructural investigation of these materials and to accurately characterize their internal porosity, starting from the tomographic dataset and employing advanced image processing techniques. The 3D visualization and analysis software Avizo Fire, combined with a custom-made application software, was used. Furthermore, the tomographic analysis has been used to evaluate the mechanical and structural properties of the foams subjected to in situ compression loading. The latter
analysis was possible thanks to a particular compression stage integrated with the CT system. The complete system constitutes a powerful facility suitable for the analysis of items having a complex internal geometry like foams - as in this case study - or parts built by additive manufacturing processes
Fatigue behavior of single crystal superalloy bars joined by capacitor discharge welding
No full textThis work concerns single crystal Ni-based superalloy welded through the capacitor discharge welding (CDW) process. The static and fatigue behavior of CMSX-4 type single crystal alloy has been analyzed, performing mechanical tests on square specimens in order to establish in detail the superalloy behavior at the expected service stresses. Tests have been conducted both at room and working temperatures (800°C), comparing base material and capacitor discharge welded joints. The material microstructure has been observed with optical and scanning electron microscopy in order to characterize welding parameters effects on the weld characteristics, analyzing base material and as-welded specimens; this way, the CDW process has been studied to perform butt joint with the better characteristics ad achieving sound welds. Microstructural modifications and the heat affected zones have been observed in the welded section as well as the interaction between weld material and parent metal. The research activities have been conducted in the frame of AWFORS project, financed by the European community
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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