1,720,962 research outputs found
Carena Trimarano per Fregata Multiruolo
No full textArticolo su rivista Tecnologie Trasporti Mare, gennaio-febbraio 200
Global Strength Assessment of a Trimaran Hull Multipurpose Frigate
No full textThis paper presents the results of a feasibility study for a general purpose frigate based on a trimaran hull, developed by Fincantieri and Cetena for the Italian Navy. Particular attention has been given to the structural design of the hull and superstructures. Starting from the results of a previous study, more concerned with the hydrodinamic design of the ship, three configurations of the hulls were chosen for further analysis and the long term loads calculated in several sea zones basing on the results of a 3D seakeeping panel method. A rule-based design of the hull was carried out, using RINA H.S.C. rules; then a 3D FEM model of the whole ship was built to directly assess the hull structure response and adequacy to bending, pitching and prying moments, by using different techniques
Design Project of a Trimaran Multipurpuose Frigate – Study of the Hydrodynamic Aspects
No full textObject of this study is the design project of a trimaran multipurpose frigate with the aim of evaluating advantages/disadvantages of a multihull configuration for new combat ships in comparison with a corresponding traditional monohull vessel.
As a first step, an analysis of existing technical literature was conducted in order to collect information about different aspects related to the project of a trimaran, then the main characteristics of the mono-hull chosen as reference were defined.
On the basis of the same operational requirements adopted in the definition of the corresponding monohull and of the information deducted by literature, the main characteristics of a trimaran configuration, identified as target vessel, were defined (i.e. dimensions and hull geometry, main hull and outrigger positioning, internal compartments definition, lay-out of general and engine arrangements, hull appendages).
Once defined the target vessel, 9 different configurations obtained changing outriggers position and hull forms were assumed in order to investigate the influence of these variations on main trimaran performances and in particular to analyse wave interference effects strictly depending on the distance between the hulls and their respective position.
Therefore 10 different configurations were obtained and for these studies of propulsion, seakeeping, manoeuvrability and stability were developed in order to compare the performance of the trimaran with the corresponding monohull.
From the results obtained it can be deduced that a trimaran offers a greater bridge area with a consequent improvement of the layout while the reduced breath of the main hull causes some problems in internal arrangement. With regard to propulsive performance a lower power is required at higher velocities but not at lower speed; the trimaran configuration moreover offers improved seakeeping even if special care is required to evaluate impacts on traversal connection between hulls. Considering manoeuvrability, the course stability of the trimaran is greater than that of an equivalent monohull with a consequent reduction of the turning ability; finally, the intact stability of the vessel is improved, while some problems can be related to damage stability.
In conclusion of this analysis concerning advantages/disadvantages of a trimaran configuration, it can be concluded that it offers some aspects of great interest for future development
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
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