1,720,964 research outputs found
Apparecchiatura per la posa di piastrelle e/o elementi decorativi e relativo procedimento
No full textSaldatura H-FSW di giunti a sovrapposizione di leghe di Al per impiego aeronautico
No full textLa friction stir welding (FSW) è una tecnica di saldatura allo stato solido che si è rapidamente diffusa in diversi settori
applicativi, principalmente per la saldatura delle leghe leggere.
La saldatura FSW su giunti a sovrapposizione si è dimostrata più difficile da condurre rispetto alla configurazione di
testa, ampiamente trattata in letteratura. In particolare, si riscontrano delle zone di discontinuità in corrispondenza
dell’interfaccia tra le lamiere saldate che assumono un profilo potenzialmente dannoso per la resistenza statica e
dinamica del giunto.
In prima approssimazione, la resistenza di questo tipo di giunzione è controllato più dalla presenza di questi difetti
macroscopici che dalla microstruttura del materiale. Perciò la valutazione delle saldature ottenute in questo lavoro si è
basata essenzialmente sulla ricerca di una correlazione tra le caratteristiche morfologiche della zona saldata e i risultati
di prove di trazione statica su campioni di saldatura.
In sintesi con questo lavoro si è voluto studiare la procedura di saldatura hybrid-FSW, messa a punto nel laboratorio
tecnologico del Dipartimento di Ingegneria Meccanica. Essa consiste nel far precedere l’utensile da un arco TIG con le
funzioni di preriscaldo del materiale base. Questa metodologia è stata applicata ai giunti a sovrapposizione di leghe di
alluminio, AA2024-T3 / AA7075-O / AA2024-T3 , tradizionalmente poco o per nulla saldabili con processi di fusione
Switching Controllers for Networked Control Systems with Packet Dropouts and Delays in the Sensor Channel
No full textSwitching policies for mold level control in continuous casting plants
No full textThe problem of controlling the liquid level in the mold of a continuous casting process is considered. Essentially, the system operates in two different modes: (a) one in which the system is affected only by small-amplitude high-frequency disturbances, and (b) one in which the system is affected by a comparatively large disturbance related to an abrupt unclogging phenomenon. To cope with the first situation, the control system must exhibit a narrow bandwidth, whereas the second situation requires a much larger bandwidth. The two conflicting requirements lead naturally to the design of two distinct controllers and a switching rule that activates either controller according to the operating condition. Due to the time-varying nature of the resulting control system, the controllers should be properly realized to guarantee stability; to this purpose, a recent result on switching systems [15] is invoked.Since the sudden switching between controllers can cause controller and actuator output bumps, a soft switching policy that still ensures stability is also proposed. Simulations and laboratory experiments carried out on an electronic analogue of the process show the effectiveness of the suggested control schemes
La rinascita. L'opera di Bruno Morassutti a San Martino di Castrozza nell'alveo del suo tempo.
No full textL'articolo affronta l'analisi di due realizzazioni residenziali progettate da Bruno Morassutti a San Martino di Castrozza (TN) negli anni 50. L''analisi della due realizzazioni, con dettagliato riferimento alla dimensione dell'interior design, viene contestualizzata in relazione alla più ampia attività progettuale di Bruno Morassutti, significativo architetto e designer (1920-2008), e all'architettura alpina, evidenziando anche rilevanti influssi internazionali, fra cui quelli neo- organici da Frank Lloyd Wright
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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