1,720,998 research outputs found
Reliability of 5-beam LDV fiberoptic probe for turbulence measurements in the wall region of open-channel flow
No full textViscosity effects on local scour around vertical structures in clear-water conditions
No full textLocal scour represents the erosion process that occurs at the base of hydraulic structures overlying sediment beds. Horseshoe vortices forming at the bed-structure junction are the main responsible for sediment removal and dictate erosion rates as well as the maximum erosion depth resulting from a significant flow event. In steady-flow conditions this is often referred to as the equilibrium scour depth, which, for many hydraulic structures, represents a key parameter for foundation-design and risk-assessment purposes. The equilibrium scour depth has been investigated for decades and many predictive formulae have been developed following the classical empirical approach, whereby numerous experimental datasets are used to isolate and identify the influence of non-dimensional groups emerging from dimensional analysis. Within this context, the influence of obstacle Reynolds numbers, and consequently of viscous forces, has always been neglected because of the large Re values normally encountered in engineering and laboratory conditions. The present paper demonstrates that this assumption is largely incorrect especially for beds made of sand or finer material. The theoretical analysis presented in Manes and Brocchini ([1]) is herein extended to include viscosity effects and investigate their importance on equilibrium scour depths forming around obstacles resembling bridge piers.</p
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
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