1,721,326 research outputs found
Warship machinery constraints
No full textThe design of warship machinery is complex because unlike most merchant ships warships do not have a unique operating profile, while designed to meet specific wartime roles, they spend the vast majority of their lives performing a wide range of different tasks. As a consequence the propulsion plant must be able to operate efficiently and effectively over a wide range of speeds. This chapter describes some of the constraints encountered when designing the main machinery components of a typical surface warship and introduces the concept of Integrated Full Electric Propulsion. A second major difference between merchant ships and warships is that the latter are designed to absorb deliberate damage and still function. A brief account of some of the threats a warship is exposed to and their associated damage mechanism is followed by an analysis of various design approaches that can mitigate these threats to ensure a warship with a high survivability
Deriving confidence in paleointensity estimates
No full textDetermining the strength of the ancient geomagnetic field (paleointensity) can be time consuming and can result in high data rejection rates. The current paleointensity database is therefore dominated by studies that contain only a small number of paleomagnetic samples (n). It is desirable to estimate how many samples are required to obtain a reliable estimate of the true paleointensity and the uncertainty associated with that estimate. Assuming that real paleointensity data are normally distributed, an assumption adopted by most workers when they employ the arithmetic mean and standard deviation to characterize their data, we can use distribution theory to address this question. Our calculations indicate that if we wish to have 95% confidence that an estimated mean falls within a ±10% interval about the true mean, as many as 24 paleomagnetic samples are required. This is an unfeasibly high number for typical paleointensity studies. Given that most paleointensity studies have small n, this requires that we have adequately defined confidence intervals around estimated means. We demonstrate that the estimated standard deviation is a poor method for defining confidence intervals for n < 7. Instead, the standard error should be used to provide a 95% confidence interval, thus facilitating consistent comparison between data sets of different sizes. The estimated standard deviation, however, should retain its role as a data selection criterion because it is a measure of the fidelity of a paleomagnetic recorder. However, to ensure consistent confidence levels, within-site consistency criteria must be depend on n. Defining such a criterion using the 95% confidence level results in the rejection of ?56% of all currently available paleointensity data entries
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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