1,721,113 research outputs found
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
Welding of high-resilience martensitic stainless steel for hydrodynamic components in innovative seacraft: a comparison of traditional and HDE technologies
No full textFor the designer, the production of innovative seacraft involves the use of atypical materials at the shipyard. This article presents a comparison between traditional (SMAW) and innovative [LBW, electron beam welding (EBW)] welding technologies to illustrate the feasibility and suitability – also in economic terms – of the penetration of new welding technologies in the shipbuilding sector. In particular, the material considered for the production of submerged bearing components in an innovative submerged-wing hydrofoil is X4CrNiMo13-4, a martensitic stainless steel presenting improved resilience chosen by the shipbuilding company (Rodriquez Cantieri Navali), above all, on account of its high mechanical strength. In order to avoid costly PWHT, which, given the large size of the components, has a heavy influence on production costs, welding procedure specifications were developed using an austenitic filler material that, while inducing a limited reduction in performance in the melt zone, allows for conspicuous economic advantages. Research has shown how EBW technology undoubtedly allows for better results, while – although it would be more suitable for large-size components – LBW technology requires a more critical optimization of parameters. © 2013, © 2013 Taylor & Francis
Superlega IN792 DS: Ottimizzazione della saldatura EB e laser e dei trattamenti post saldatura
No full textNickel-based superalloys are widely used in the fabrication of high temperature components (discs and vanes) of aeronautical turbines and power plants. Their structure consists, quite simply, of two phases: a disordered matrix (phase ã) reinforced by a second ordered intermetallic phase precipitation, i.e: Ni3 (Al, Ti) phase ã'. In service operation, the nickel superalloy mechanical parts are subject to surface cracking. Given the high cost production, their repair by welding/remelting with material adduction can be a valid solution for the life extension of the components. This paper presents the results of electron beam and laser beam repair welding optimization through re-melting tests analysis conducted on 2 mm thick plates obtained from a directionally solidified IN792 ingot (DS). The results show how, both with EBW and LBW, a preheating (PHT) at 300 °C is necessary to avoid hot cracking initiation followed by a subsequent post-weld heat treatment (PWHT) for stress relieving. For both techniques, the microstructure shows how the ratio between ã'/ã phases goes from 70/30 of the base material to 30/70 of the fused zone (ZF). It has been possible to realize crack-free remelting, however the laser technique (LBW) remains more susceptible to the porosity compared to the electron beam welding (EBW). © 2018 Instituto Italiano della Saldatura. All rights reserved
Laser welding of aluminum foam sandwich panels [Saldatura laser di pannelli sandwich in schiuma di alluminio]
No full textThe paper describes the results about the laser and laser-TIG welding of Aluminum Foam Sandwich. The panels used are produced by powder metallurgy technology and this permits to have a metallurgical bonding between skin and core. So, this material is completely metallic and has an excellent stability even in case of fire. These features allow to choose the ASF as new lightweight material for structural components also in the field of transport. One of the limitations relating to this type of materials is the maximum available size (2.5 × 1.2 m), which requires the development of special processes of junction with low heat input to reduce, as much as possible, the dimension of the area affected by the welding process. It should be considered the fact that it is possible to weld only the skins of the sandwich, so a discontinuity in the core remains intrinsic to the welding process. Therefore, it is appropriate to employ a transition element in the welding line to achieve a link between the two skins. The troubleshooting about the laser welding regards both: the common difficulties in the laser welding of the aluminum alloys of the skin and some other problems due to the presence of eutectic alloys in the core than we can't remove completely
Processi di fabbricazione di profilati estrusi rinforzati con schiuma metallica
Get PDFIl presente report descrive le fasi di calibrazione del forno di schiumatura per la realizzazione di compositi metallo-metallo costituiti da un profilato in Alluminio AA6060 e da un core in schiuma metallica ottenuto mediante la schiumatura di un precursore commerciale Alulight eutettico di tipo AlSi10 contente lo 0.8% in peso di agente schiumante (TiH2). Il primo capitolo riguarda l’analisi dei parametri di controllo, temperatura e tempo, e la loro correlazione (anche mediante Design of Experiment) con i dati di risposta, principalmente espansione e densità, considerando un piano sperimentale fattoriale con tre livelli di tempi di schiumatura, due livelli di temperatura e due condizioni di raffreddamento, effettuato con due repliche. In particolare, le due repliche sono state effettuate in due punti distinti del forno, evidenziando differenze sostanziali in funzione della temperatura rilevata nel piattello del crogiolo. Con i dati derivanti dall’analisi di immagine e dall’analisi DOE (riferita anche alle misure di espansione mediante sensore laser) sono stati effettuati test di schiumatura in cilindri estrusi, di diametro 30 mm, altezza 40 mm e spessore di parete 2 mm, con l’obiettivo di raggiungere una densità del core di 0.55 g/cm3 +/- 0.05 g/cm3. I parametri per questi test sono stati definiti considerando i limiti imposti dalla temperatura massima (per evitare la fusione o l’eccessivo rammollimento dell’estruso) e utilizzando tempi ottimizzati in funzione delle maggiori masse in gioco, rispetto alla schiumatura di semplici granuli di precursore. Ulteriori test preliminari sono stati realizzati su campioni cilindrici di lunghezza 120 mm: questi hanno tuttavia indicato la necessità di modificare il set up di prova, con un affinamento dei parametri di processo possibile solo mediante l’impiego di un sistema di carico, scarico e raffreddamento automatico dei campioni (descritto nel report RdS/2012/099 e in fase di acquisizione)
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
- …
