1,720,963 research outputs found
Influence of Weber number on Surface Piercing Propellers model tests scaling
No full textInterest in Surface Piercing Propellers (SPP) application has increasingly grown in consideration during the last years, especially in the field of fast crafts for leisure, competition and even naval application. Unfortunately, behaviour of this kind of propulsion system is still far to be completely investigated, due to its relatively recent introduction, the limited (but increasing) range of applications and the fact that data are in many cases considered as protected know-how. Among the various problems which have to be considered in the design phases of this kind of propeller, the present work addresses some aspects of scaling the performances from model tests data, and in particular the influence on Weber Number is further analysed following a series of studies performed in the last decade by University of Genoa and University of Naples, stressing its effect not only on the critical advance coefficient determination, but also on the whole typical propeller thrust and torque coefficients
Investigation into the hydrodynamic Characteristics of a Catamaran with central streamlined Bodies
No full textFrom Model Scale to Full Size. On Turbulence Stimulation in Resistance Model Tests of High Speed Craft
No full text
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
PRISMATIC HULL TESTS IN REGULAR WAVES IN DIN TOWING TANK
No full textPRISMATIC HULL TESTS IN REGULAR WAVES IN DIN TOWING TANK
Begovic Ermina, Boccadamo Guido, Bove Andrea, Caldarella Sebastiano
Department of Naval Architecture, University of Naples Federico II, Naples, Italy
1. Introduction
Dipartimento di Ingegneria Navale (DIN) of Università degli studi di Napoli
Federico II has a towing tank of 137.2 m length, equipped with towing carriage with
maximum forward speed of 10 m/s to perform the model tests for ship resistance
prediction. This dimension of towing tank and carriage maximum speed allow relatively
huge models and very good tank-sea correlation. Resistance and powering
characteristics have been conducted both for conventional ship and for fast planning
hulls. Furthermore, multi hull configurations like catamaran, trimaran and pentamaran
ship models have been subject of research during last years.
State of the art in naval architecture indicates that the significant improvements in
ship resistance characteristics were obtained using the optimised hull forms and
consequently the cruising speed was increased. On the other hand, increasing speed and
security of vessels calls for a better understanding of the seakeeping so ship behaviour
in rough water become one of the principal interests of scientific community both as
development of numerical prediction method and as experimental determination of ship
responses.
Considering seakeeping of ships means practically to constrain the attention mainly
at vertical accelerations, relative vertical motions between ship and waves, slamming,
water on deck and wave bending moments and shear forces. Vertical motions and
accelerations result in loads on structures, cargo and equipment and are the main reason
for seasickness. It is evident that this aspect will be the most important for the passenger
ships in order to increase the comfort on board. Relative vertical motions are used to
evaluate the possibility and damage due to slamming and water on deck and therefore
are important to be improved the safety of ship. As regard the exciting loads (i.e. wave
bending moments and shear forces) generated in the interaction of ship advancing at
“constant” speed in confused sea it is of paramount importance for the structure to be
dimensioned appropriately.
Within the frame of the Competence Regional Centre “Transport”, a project financed
by the Campania Region (Mesure 3.16 POR Campania 2000- 2006), started in
November 2002, to develop a research structure equipped with some technological
laboratories and capable to integrate the competences of Universities and Research
Corporations, acting in the Campania Region, DIN was one of Departments of
University of Naples Federico II selected to get financial resources for technological
development and improvement of laboratory facilities. At towing tank new electric
feeding system has been installed and new acquisition system has been developed.
Recently, a wave maker designed by Edinburgh Designs Ltd, chosen in open bid, has
been installed at DIN towing tank with the aim to extend the tank possibilities also to
seakeeping tests.
In this work, the first seakeeping tests conducted at DIN towing tank equipped with
new wavemaker for the prismatic hull form, typical for the planning ships are presented.
The idea for the project demonstrator was to highlight the possibility of towing tank –
towing carriage – wavemaker for the prediction of high speed craft behaviour in rough
sea, as it is considered one of the most important subject of scientific research. For the
validation of ship performance in rough sea, the vertical motions i.e. heave and pitch
have been considered as the most influencing for comfort on board.
The tests are relative to 28 m length high speed craft cruising at speed of 30 knots in
regular waves
PRISMATIC HULL TESTS IN REGULAR WAVES IN DIN TOWING TANK
No full textPRISMATIC HULL TESTS IN REGULAR WAVES IN DIN TOWING TANK
Begovic Ermina, Boccadamo Guido, Bove Andrea, Caldarella Sebastiano
Department of Naval Architecture, University of Naples Federico II, Naples, Italy
1. Introduction
Dipartimento di Ingegneria Navale (DIN) of Università degli studi di Napoli
Federico II has a towing tank of 137.2 m length, equipped with towing carriage with
maximum forward speed of 10 m/s to perform the model tests for ship resistance
prediction. This dimension of towing tank and carriage maximum speed allow relatively
huge models and very good tank-sea correlation. Resistance and powering
characteristics have been conducted both for conventional ship and for fast planning
hulls. Furthermore, multi hull configurations like catamaran, trimaran and pentamaran
ship models have been subject of research during last years.
State of the art in naval architecture indicates that the significant improvements in
ship resistance characteristics were obtained using the optimised hull forms and
consequently the cruising speed was increased. On the other hand, increasing speed and
security of vessels calls for a better understanding of the seakeeping so ship behaviour
in rough water become one of the principal interests of scientific community both as
development of numerical prediction method and as experimental determination of ship
responses.
Considering seakeeping of ships means practically to constrain the attention mainly
at vertical accelerations, relative vertical motions between ship and waves, slamming,
water on deck and wave bending moments and shear forces. Vertical motions and
accelerations result in loads on structures, cargo and equipment and are the main reason
for seasickness. It is evident that this aspect will be the most important for the passenger
ships in order to increase the comfort on board. Relative vertical motions are used to
evaluate the possibility and damage due to slamming and water on deck and therefore
are important to be improved the safety of ship. As regard the exciting loads (i.e. wave
bending moments and shear forces) generated in the interaction of ship advancing at
“constant” speed in confused sea it is of paramount importance for the structure to be
dimensioned appropriately.
Within the frame of the Competence Regional Centre “Transport”, a project financed
by the Campania Region (Mesure 3.16 POR Campania 2000- 2006), started in
November 2002, to develop a research structure equipped with some technological
laboratories and capable to integrate the competences of Universities and Research
Corporations, acting in the Campania Region, DIN was one of Departments of
University of Naples Federico II selected to get financial resources for technological
development and improvement of laboratory facilities. At towing tank new electric
feeding system has been installed and new acquisition system has been developed.
Recently, a wave maker designed by Edinburgh Designs Ltd, chosen in open bid, has
been installed at DIN towing tank with the aim to extend the tank possibilities also to
seakeeping tests.
In this work, the first seakeeping tests conducted at DIN towing tank equipped with
new wavemaker for the prismatic hull form, typical for the planning ships are presented.
The idea for the project demonstrator was to highlight the possibility of towing tank –
towing carriage – wavemaker for the prediction of high speed craft behaviour in rough
sea, as it is considered one of the most important subject of scientific research. For the
validation of ship performance in rough sea, the vertical motions i.e. heave and pitch
have been considered as the most influencing for comfort on board.
The tests are relative to 28 m length high speed craft cruising at speed of 30 knots in
regular waves
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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