1,721,020 research outputs found
The Oligocene mollusc types of Gaetano Rovereto from Carcare, Dego, Squaneto, and Tagliolo areas (Tertiary Piedmont Basin, NW Italy).
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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
The manoeuvrability of high-speed craft in the following sea
No full textBroaching-to is a highly complex, non-linear dynamic instability event that several vessels might face when sailing in the same direction of the waves, for example when returning to port during a storm. This condition is referred to as following sea. Vessels such high-speed craft but also patrol and rescue boats, fishing trawlers or small frigates are the most subjected to the severity of the sea, and therefore also the most vulnerable to the broaching. A broach occurs when the ship is captured by the incoming stern waves (surf-riding), and is turned beam-to-sea by the large wave yawing moment. This yawturning motion is so sudden and the acceleration is so high that even the most skilled mariners are not able to avoid it, losing dangerously the control of the vessel. In extreme cases, a broach can cause the capsize of the vessel.The first apparitions of the term broaching-to date back to the 18th century. Sailors have always been frightened by the potentially devastating consequences of sailingwindward, but this phenomenon has been consistently studied starting from the 1950s only. Several naval architects put in evidence the main characteristics of the physical phenomenon of the broaching-to in following sea, developed useful and accurate techniques meant to predict the behaviour of the vessel sailing in those scenarios. Although the great efforts spent in the research on this subject, there is still some uncertainty about the causes of a broaching-to event, and about the characteristics of the vessel that might lead to an unsafe behaviour in following waves. This thesis aims to investigate these aspects, with the final desirable result of providing guidelines for safer vessels to designers and shipbuilders
The mollusk type-material of Gaetano Rovereto in the “BTP Collection” (Museo di Paleontologia - DISTAV - Università di Genova): the Oligocene types from Mioglia area.
No full textThe present paper examines the types of the gastropod, cephalopod, and bivalve new taxa described by Gaetano Rovereto in the years 1897-1914 from the Oligocene rocks of Mioglia area (Molare Formation and Rocchetta-Monesiglio Formation, Tertiary Piedmont Basin, Southern Piedmont - Central Liguria, NW Italy). These taxa are part of the “Collezione BTP” (BTP Collection) housed at the Dipartimento di Scienze della Terra, dell’Ambiente e della Vita - DISTAV - of the Università di Genova. The Mioglia area collecting sites reported on in Rovereto’s papers have been verified on field. In the Mioglia area, Rovereto identified six new species of gastropods (preserved in the BTP Collection), one of cephalopods (preserved) and 17 new taxa of bivalves (16 preserved, one lost). This paper focuses on six gastropod, one cephalopod and 14 bivalve taxa originally described by Rovereto and presently included in the BTP Collection. As a result of this revision some taxa were confirmed, others were put into synonymy and others have undergone a change of genus attribution
Method for estimating parameters of practical ship manoeuvring models based on the combination of RANSE computations and System Identification
No full textIn this work a method for estimating parameters of practical ship manoeuvring models based on the combination of RANSE computations and System Identification procedure is investigated, considering as test case a rather slender twin screw and two rudders ship. The approach consists in the estimation of the hydrodynamic coefficients applying System Identification to a set of free running manoeuvres obtained from an in-house unsteady RANS equations solver, which substitute the usually adopted experimental tests at model or full scale. In this alternative procedure the numerical quasi-trials (in terms of kinematic parameters time histories and, if needed, forces time histories) are used as input for the System Identification procedure; the aim of this approach is to reduce external disturbances that, if not properly considered in the mathematical model, may compromise the identification results, or at least amplify the well-known “cancellation effects”. Furthermore, the CFD results provide information both in terms of flow field variables and hydrodynamic forces on the manoeuvring ship. These data may be adopted for a better understanding of the complex flow during manoeuvres, especially at stern, providing also additional information about the interaction between the various appendages (including rudders) and the hull. The identification procedure is based on an off-line genetic algorithm used for minimizing the discrepancy between the reference manoeuvres from CFD and those simulated with the system based modular model. The discrepancy was measured considering different metric functions and simplified formulations which consider only the main macroscopic parameters of the manoeuvre; the metrics have been analysed in terms of their capability in reproducing the time histories and in limiting the cancellation effect of the hydrodynamic derivatives
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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