1,720,958 research outputs found
FASTER THAN THE WIND: ANALYSIS OF ROTOR GEARED VEHICLES
No full textAbstract. This paper deals with the analysis of vehicles capable of travelling dead downwind
or dead upwind faster than the wind. Vehicles powered by traditional sails can reach velocities
larger than the wind speed, but they are not capable of doing that travelling directly upwind
or directly downwind, this type of vehicles reach their best performances maintaining a
course angled compared to the wind direction. In order to travel directly upwind and to try to
go faster than the wind both dead upwind and dead downwind vehicles employing a rotor
may be used. Despite the fact that the testing of this type of vehicle has been documented
since the mid of the 20th century a complete analysis of factors influencing performances of
this type of vehicle is not available. This paper represents a first attempt to fill this gap.
The paper is divided in 2 main sections, the first section is introductory and it contains a discussion
concerning the meaning of the sentence “faster than the wind” this discussion allows
to establish differences existing between traditional sail powered vehicles and rotor powered
vehicles. The second section is devoted to the analysis of latter type of vehicle and can be divided
in 4 parts. The first part is focused on the identification of all possible configurations of
motion that can be obtained as a function of how the rotor may be connected to the wheels.
The second part deals with the analysis, for the two configurations identified in the first part,
of the dynamic conditions leading to the start of the motion in the downwind or in the upwind
direction. The third part, in order to investigate the sustainability of the initial motion, focus
on the derivation of equations of motion for the configurations described. The forth part, in
order to investigate the capability of the described configurations to reach velocity larger
then the wind speed, analyze the evolution of the apparent velocity acting on the rotor blades.
Finally some considerations concerning the optimization of the vehicle design are presented
An optimized SPH algorithm for neighboring particles identification in free surface flows
No full textAnalisi delle perdite in un sistema di distribuzione idrica in pressione. Relazione tra leggi di efflusso locale e globale
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
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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