1,721,047 research outputs found
INVESTIGATION ON MODEL-SHIP CORRELATION AND ON POWER PREDICTION FOR HIGH SPEED MULTI-HULLED VESSELS
No full textCrete (Greece
Experiments and Computations of non linear effects on the motions of Catamaran Hulls
No full textAim of this paper is to analyze the influence of wave steepness on nonlinear ship motions, as well as the
capability of a weakly nonlinear seakeeping methodology to predict the related nonlinear effects. Experimental
tests and numerical simulations have been performed for two catamaran vessels: one with round bilge and the
other with a hard chine hull form. Regular head waves of different wave length combined with two wave slopes
have been considered.
In the numerical analyses, the nonlinear forces are evaluated in the time domain and the equations of motion are
solved in the frequency domain. This procedure iteratively passes from the frequency to the time domain and
allows to avoid the initial transient phase, resulting faster than the classical approach based on the time domain
only. For solving the relevant boundary value problems in the frequency domain a three-dimensional Rankine
panel method has been employed which has the capability to deal with the complex free surface flow pattern
between the hulls of multi-hull vessels. Examining the experimental data and the related numerical results,
conclusions are drawn about the influence of the wave slope and about the capability of the numerical method to
consider such influence
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
Steady Waves of Series 60 - Cb = 0.7 Hull. Numerical Results and Experiments on Geosims
No full textA numerical boundary element method for the evaluation of the wave pattern and of the wave resi stance is discussed and applied to a ship hull of Series 60 with CB = 0.70. The methodology is based on distribution of sources on the relevant boundary surfaces. The theoretical wave resistance has been obtained both by pressure integration and by analyzing the transverse cuts of the wave patterns obtained numerically. Furthermore, experimental investigations have been carried out in towing tanks with three geosim models of Series 60 hulls, having CB = 0.7, in order to determine the wave resistance by single longitudinal cut and multiple wave pattern cut methods, the form factor and the data processing to full scale from the model results was obtained by using the ITTC ’78 methodology.
The main aim of the paper is to furnish a contribution on the following still open problems: validation of the numerical method for the evaluation of the wave pattern and the wave resistance; determination of the scale effects both on the form factor and on the wave pattern resistance; deeper understanding of the wave breaking phenomenon and evaluation of the scale effect on the wave breaking resistance
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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