1,721,081 research outputs found
Detecting contact areas in vibrating steel beams using Energy Flux
No full textThe world faces an increasing energy problem, forcing people to search for sustainable energy sources. Offshore wind energy has shown great potential to financially compete with traditional energy sources. Recent developments like the slip-joint connection increase this potential. However, for further optimization of the design of a slip-joint, the location of the contact areas between the two cones must be known. Previous attempts to detect these contact areas based on techniques such as heat transfer or ultrasonic measurements have proven insufficient. A possible new way of detecting contact areas, is through the behaviour of Energy Flux. Energy Flux methods have shown great potential as a damping identification tool in other applications. Therefore, in this study the relation between Energy Flux behaviour and the presence of a contact point in the time-, frequency- and time-frequency-domain is studied. To this end, a numerical analysis of a vibrating simply supported Euler Bernoulli beam is conducted, simulating a contact area with a point load. The analysis in the frequency-domain showed the most promising results. Presence of a contact point (i) introduces peaks at twice the first and twice the second eigenfrequencies, and (ii) increases peak height at the location of the contact point. The pressure of the simulated contact point increased these effects. In the time-domain the presence of a contact point increased the amplitude of the cumulative energy flux. This change was most significant at the antinode of the first eigenmode. The location of the contact point was of little influence on this effect. These results show that the presence of a contact area influences the behaviour of the energy flux. The results are encouraging for a later implementation of the energy flux method for the detection of contact areas in a slip-joint. As a validation of these results, an experiment has been proposed. After execution of this experiment, further research is needed in (i) the behaviour of Energy Flux in a conical shape, and (ii) Energy Flux measurements of higher frequencies.Civil Engineerin
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
The cross-sectional and time-series prediction of cryptocurrency returns - A comprehensive study
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