1,721,396 research outputs found
Inclined shaft propeller flows
No full textMost planing boats and other high speed craft driven by water screw propulsion have their propellers on an inclined shaft leading to an oblique inflow relative to the propeller axis. There is thus a circumferential variation of the tangential component of the inflow to the blade giving rise to a cyclic variation in blade load. This work details the results of an experiment investigation into the flow field around such a propeller and various methods of predicting, theoretically, overall propeller performance on an inclined shaft in non-cavitating flows. The experiment work utilised the recently developed technique of laser doppler anemometry. An instrument operating in the 'reference beam' mode and capable of the simultaneous measurement of two velocity components was used to obtain real time velocity records at various points in the flow field around a propeller in a cavitation tunnel. The technique does not rely on any probes within the flow and so enables information to be obtained very close to the propeller. Response time is rapid enough for all flow unsteadiness to be recorded. Several theoretical models were developed to predict propeller performance using unsteady 2D foil theory. The limited scope of these theories led to the development of an unsteady lifting line model based on published lifting surface methods. Incorporated into this model are arbitrary wake orientation, an image system and the facility to predict field point velocities and hull pressures. Correlation with experiment results shows reasonable agreement for mean velocity levels within the known limitations of the model used.</p
Hundreds of millions of microplastic particles could be flowing into UK rivers, hidden in raw sewage
No full textMicroplastics are everywhere. Snow close to the peak of Mount Everest was found to contain on average 30 microplastic particles per litre. And 11,000m below sea level, in the Pacific Ocean’s Mariana Trench, an average of 2,200 microplastic particles per litre of sediment were found.Microplastics are bits of plastic smaller than 5mm in diameter. They come from a range of sources including toiletries, cosmetics, fibres from washing our clothes, plus a range of other routes, such as road paints, tyre wear and fragments of litter. Scientific reports are showing astounding amounts of these plastics globally, including in remote areas, but those numbers have been significantly underestimated.Recently, there was public anger over revelations that Thames Water, a UK utilities company, released 2 billion litres of raw sewage into the River Thames in just two days. This is on the back of Southern Water’s record £90 million fine for thousands of illegal raw sewage discharges over several years. However, these stories do not report on the amount of microplastics that would have also been released within these discharges as that data is not routinely collected.Applying an example of the average numbers of microplastics found in a litre of effluent to the amount released in the Thames case could equate to about 500 million microplastic particles entering the River Thames. This is happening all over the UK, with raw sewage being deposited along many British coastlines and rivers
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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