1,720,956 research outputs found
Experimental characterization of two CP propellers at different pitch settings, considering cavitating behaviour and related noise phenomena
No full textPropeller design has evolved significantly in last years, with the introduction of numerical methods which can provide a very reliable assessment of propeller characteristics, not only in correspondence to the usual design conditions, but also to off-design conditions. Nevertheless, problems still exist if “very off-design conditions” are considered, and if interest is posed on cavitation related problems such as radiated noise. Interest in radiated noise phenomenon is constantly increasing, not involving anymore only naval vessels, but affecting also design of other “high added value ships”, such as cruise ships and megayachts, for which comfort problem and environmental impact are a key element. One of the most significant problems related to radiated noise, is the rather low amount of experimental data available, and this is particularly significant for CPP propellers at off design conditions. In present paper, the experimental characterization of two alternative designs of a CP propeller in terms of usual mechanical characteristic, cavitation and radiated noise is presented. Experimental campaign has been conducted considering two very different pitch settings, allowing to analyse propeller behaviour also in correspondence to very off design conditions
COGAS Plant as Possible Future Alternative to the Diesel Engine for the Propulsion of Large Ships’
No full textNumerical and Experimental characterization of a CP propeller unsteady cavitation at different pitch settings
No full textPaper presents results obtained in a study dedicated to the experimental and numerical investigation of the steady and unsteady hydrodynamic characteristics of a modern CP propeller including off-design operating conditions, i.e. with the blade oriented at a pitch rather far from the design value. The extensive experimental campaign has offered the opportunity to validate the accuracy of two different CFD methods: a first order unsteady panel method with some non linearities (in the Kutta condition and flow adapted wake); and a state of the art RANSE solver, Also the unsteady conditions of the CP propeller are investigated at two very different pitch settings, The comparison of numerical predictions with experimental results shows a very good agreement of both the numerical methods with the experiments at design pitch, also with regards to cavitation predictions. On the contrary, results at highly reduced pitch show the limits of the conventional panel method, based on potential flow solution, for which the usual viscous corrections are not any more sufficient to cope with separated viscous flow of some blade sections, which are satisfactorily modeled by the RANSE solver, instead. From a careful comparison of the flow characteristics predicted by the two different numerical methods, some hypothesis for future enhancement of the panel method are formulated in the conclusions
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
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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