1,721,062 research outputs found
Hydrodynamic analysis of ship manoeuvrability at ports using CFD
No full textThe way a ship moves in restricted waters is significantly different from how it moves in open waters due to the impact of limited depth conditions. This is because ships often operate in shallow water areas like ports or harbours. To understand these effects on ship manoeuvrability, the manoeuvrability of the KRISO Container Ship (KCS) model was studied at ports using unsteady Reynolds-Averaged Navier-Stoked computations combined with 6 degree-of-freedom (DOF) rigid body motion equations. The study used an adaptive dynamic mesh approach to allow the vessel to move freely and for the rudder to be controlled. Simulation tests were performed at ports modelled as restricted waters with varying water depth to draft ratios, and results were partially validated with experimental data. The findings showed that the ship's forward movement, lateral movement, and tactical diameter increased as the water depth to draft ratio decreased, linked to the complex interactions between the hull wake, boundary layer, propeller, vortex, and bottom of the seabed.</p
A method for the quantitative assessment of performance of alternative designs in the accidental condition
No full textExperimental Assessment of Intact and Damaged Ship Motions in Head, Beam and Quartering Seas
No full textThis paper presents an extensive study on the experimental prediction of motions for the well-known 5415 frigate hull in intact and damaged conditions. The experimental campaign is conducted for two geosim models, 1/100 and 1/51 scale, at zero speed in head, beam and quartering seas. All experimental results for 1/51 model are presented as 1st and 2nd order RAO, commenting on physical reasons for second order response occurrences. The results show the changes in motion responses when a ship hull is in damaged condition, they highlight the model scale effects and demonstrate the comparisons between the tests in which the model may freely drift and those in which the mean position of the model is restrained. For damaged ship in free drift tests the damage opening orientation is varied and its effect on RAO and free drift velocity is commented
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
An experimental study of hull girder loads on an intact and damaged naval ship
Get PDFThe study reported in this paper is focused on experimental investigation of the hull girder loads on an intact and damaged naval ship DTMB 5415 at zero speed. The experimental campaign was carried out in head and beam regular waves at the University of Strathclyde. The effect of the use of moorings in the model experimental setup was investigated in the context of loads assessment, and the moorings are shown to influence the measured hull girder loads at some wave frequencies compared to the free drift case. Therefore the tests in beam seas are performed with free drifting model while the moored model setup was adopted for head seas. The results for ship motions are compared with those from a previous campaign giving an insight into repeatability and uncertainty of measurements. The roll decay of the ship in both intact and damaged conditions is analysed and the linear and quadratic extinction coefficients for the model and the ship scale are reported and detailed discussion on intact-versus-damaged ship roll damping behaviour is given. The results for the hull girder loads are presented for intact and damaged ship. An investigation of the nonlinear effects due to wave height variation in the range wave height to wave length from 1/50 to 1/22 on the shear force and bending moment values was carried out for a range of wave lengths to ship length ratios from 0.8 to 1.4. The results of the extensive campaign are compared against similar experimental studies forming a benchmark data for validation of numerical methods
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
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