1,720,975 research outputs found
Sperimentazione di un motore ad accensione comandata alimentato con miscele di idrogeno e metano
No full textLa presente memoria descrive un’attività sperimentale di ricerca volta a quantificare le prestazioni, in termini di consumi ed
emissioni, ottenibili da un motore ad accensione comandata trasformato per essere alimentato con miscele idrogeno e metano.
Le prove sono state condotte su un motore Iveco Daily di cilindrata 2800 cc aspirato con iniezione elettronica multi-point
originariamente funzionante a metano. L’analisi ha previsto l’impiego di più miscele metano-idrogeno caratterizzate da diverse
concentrazioni di idrogeno, con valore massimo pari al 35% in volume.
Le attività presentate sono le prime effettuate nell’ambito di una ricerca piu’ ampia, e tuttora in svolgimento, sviluppata
nell’ambito del Progetto Europeo LIFE+ denominato H2 POWER - Hydrogen in fuel gas, finalizzato alla verifica della
possibilità di realizzare un motore per mezzi di trasporto pubblico nei quali la percentuale di idrogeno sia variabile in tempo
reale in funzione del carico richiesto su strada.
Nei test sperimentali è stato fatto funzionare il motore sia a pieno carico, per valutarne le prestazioni massime in tutto il
range ammissibile di giri motore, sia a carico parziale in un determinato punto motore per verificare gli andamenti di consumi,
rendimenti ed emissioni, dipendenti dalle miscele impiegate e dalle strategie di iniezione e controllo motore.
In questo lavoro è risultata molto evidente la drastica riduzione delle emissioni di NOx all’aumentare dello smagrimento
della miscela combustibile. In particolare con idro-metano al 35% si ottiene una notevole riduzione delle emissioni grazie
all’elevata infiammabilità dell’idrogeno che consente una corretta combustione anche con valori di miscela magra altrimenti
non raggiungibili. In prospettiva, questo potrebbe consentire l’eliminazione della funzione riducente del catalizzatore. Anche i
consumi specifici risultano nettamente inferiori, soprattutto in condizioni di alimentazione magra
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
Subependymal periventricular heterotopias in a patient with ehlers-danlos syndrome: a new case
No full textEhlers-Danlos syndrome is a complex hereditary connective tissue disorder that is characterized by abnormalities of the skin and joints and visceral and neurological manifestations. At present, at least 11 forms are recognized on the basis of their clinical characteristics, methods of transmission, and biochemical defect. The neurologic manifestations include cerebrovascular disease, peripheral neuropathy, plexopathy, periventricular subependymal heterotopias, and epilepsy Previously, 2 females were reported to be affected with subependimal periventricular heterotopias and Ehlers-Danlos syndrome type 1. The authors report a new case of a 12-year-old girl with similar clinical and neuroradiological features
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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