1,721,018 research outputs found
On the Pressure Relief Valve for the Lubrication System of an Internal Combustion Engine
No full text
Sulla Modulazione della Portata di un Elettroiniettore per Sistemi di Alimentazione Common Rail. Studio Teorico Sperimentale
No full textIl comportamento dinamico di un elettro iniettore per sistemi di alimentazione del tipo common rail è analizzato in termini di modulazione della legge di iniezione. L’adozione di
una siffatta legge di iniezione si rivela il mezzo più indicato per controllare i processi termofluidodinamici interni alla camera di combustione in vista di ottimizzare prestazioni e di minimizzare le emissioni allo scarico. Nei sistemi di iniezione common rail convenzionali, è particolarmente difficile controllare il processo di iniezione essenzialmente a causa della costanza della pressione nel rail che determina un profilo pressoché rettangolare per pressioni di iniezione elevate. Il presente lavoro è indirizzato al conseguimento di una possibile modulazione della legge di iniezione, prendendo in esame iniettori con uguale polverizzatore
ma differenti valvole di controllo. I risultati mostrano che la legge di iniezione dipende dalle modifiche geometriche eseguite nello stadio pilota dell’elettro iniettore, anche se detta modulazione appare più evidente per valori di pressione nel rail medi e medio-bassi piuttosto che alti
Investigation on Realizing Fuel Rate Shaping Using a Common Rail Injector
No full textThe present work deals with the first researches into the
real capabilities of an electronically controlled injector for
common rail systems in realizing a proper shaping of the fuel
rate with particular reference to its rising profile. Injectors
equipped with standard and geometrically modified control
valves have been investigated in detail by means of computer
modeling and simulation. Experiments have been carried out in
order to validate the feasibility of such a shaping and the
injection rate meter based on the method proposed by Bosch
was used. The main result of this work is a noteworthy
dependence of the fuel rate on geometrical modifications in the
piloting stage of the injector, since a certain difference in the
slope of the first part of the fuel rate has been attained. The
injector model has been finally used to investigate further
geometrical modifications to be realized in order to achieve the
desired fuel rate shaping
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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