1,720,979 research outputs found
Anodizing by Electrochemical Oxidation (ECO) of the Laser Powder Bed Fusion-processed A357 aluminium alloy: microstructural characterization and dry sliding behaviour
Full text linkConsidering the increasing interest for Al alloys in the packaging industry, where component lightweighting allows higher
process efficiency, as well as the increasing use of additively manufactured parts, which may not show a satisfactory tribological
behaviour in the as-built condition, anodising by Electrochemical Oxidation (ECO) and Plasma Electrolytic Oxidation
(PEO) was applied to as-built A357 (AlSi7Mg0.6) produced by Laser Powder Bed Fusion (LPBF). ECO allowed to
compensate surface and surface-connected defects in LPBF A357 and produced a thicker, less-defective anodic oxide than
PEO, providing higher wear resistance whilst maintaining a lower Coefficient of Friction (COF) in dry sliding tests against
100Cr6 steel. Polishing before ECO only resulted in negligible friction and wear improvements, even if it improved the
compactness of the anodic oxide
Microstructural characterization and hardness properties of electric resistance welding titanium joints for dental applications
No full textThe electric resistance welding procedure is used to join a titanium bar with specific implant abutments in order to produce
a framework directly in the oral cavity of the patient. This investigation studied the effects of the welding process
on microstructure and hardness properties of commercially pure (CP2 and CP4) Ti components. Different welding powers
and cooling procedures were applied to bars and abutments, normally used to produce the framework, in order to
simulate the clinical intraoral welding procedure. The analyses highlighted that the joining process did not induce appreciable
changes in the geometry of the abutments. However, because of unavoidable microstructural modifications in the
welded zones, the hardness decreased to values lower than those of the unwelded CP2 and CP4 Ti grades, irrespective
of the welding environments and parameters
Sistemi multistrato per il miglioramento del comportamento tribologico dell'acciaio inossidabile AISI 316L: cementazione a bassa temperatura seguita da deposizione PACVD di carbonio amorfo (a-C:H)
Full text linkGli acciai inossidabili austenitici presentano ottime caratteristiche che li rendono ideali in tutti quei settori in cui è richiesta un’elevata resistenza alla corrosione associata a caratteristiche estetiche e funzionali. L’acciaio AISI 316L risulta essere uno dei più studiati ed utilizzati, specie nell’industria alimentare e farmaceutica, dove leapparecchiature debbono poter essere sottoposte ad aggressive procedure di
sanificazione. Tuttavia, la modesta resistenza meccanica e la bassa durezza superficiale di questo acciaio determinano un comportamento non soddisfacente dal punto di vista dell’usura da strisciamento in assenza di lubrificanti, situazione che si verifica sovente in molti macchinari dedicati a queste industrie. Tra le varie soluzioni, studiate per migliorare il suo comportamento tribologico, la cementazione a bassa temperatura (LowTemperature Carburizing, LTC) seguita dalla deposizione PE-CVD (Plasma-Enhanced Chemical Vapour Deposition) di un rivestimento di carbonio amorfo idrogenato (a-C:H), sembra essere molto promettente.
In questo lavoro vengono analizzate le caratteristiche tribologiche dell’acciaio AISI 316L cementato a bassa temperatura e rivestito di carbonio amorfo idrogenato, tramite prove tribologiche di strisciamento non lubrificato in geometria di contatto pattino su cilindro. Sono state verificate, inoltre, le caratteristiche microstrutturali e meccaniche superficiali del rivestimento multistrato LTC/a-C:H tramite osservazioni morfologiche/topografiche, analisi in spettroscopia micro-Raman e misure di indentazione strumentata sulle superfici rivestite, seguite da analisi metallografia e misura dei profili di microdurezza Vickers in sezione trasversale. I risultati ottenuti
dimostrano che, ai fini di contenere l’effetto negativo legato all’aumento di rugosità dovuto al trattamento LTC, è opportuno effettuare una lucidatura precedente al trattamento stesso, poiché effettuandola successivamente si rischierebbe dicomprometterne lo strato efficace. Inoltre, si osserva come il trattamento LTC incrementi le capacità del substrato di supportare il rivestimento a-C:H, portando ad un miglioramento delle prestazioni tribologiche, nelle prove di strisciamento non lubrificato. Infine, si dimostra come l’utilizzo di un rivestimento a base di carbonio amorfo idrogenato adeguatamente supportato permetta una riduzione dell’attrito (di oltre cinque volte) e dell’usura (di circa dieci ordini di grandezza) rispetto ai corrispondenti materiali non rivestiti
Influenza della microstruttura sul comportamento a fatica di leghe di alluminio e compositi con rinforzo particellare
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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