1,720,981 research outputs found
Buckling of Structures Under Tensile Dead Loading
No full textPossibility of bifurcations for structures subjected to tensile loads are investigated.
Examples of such structures are shown.
Theoretical findings are succesfully compared to experimental results
Tutto quello che avreste voluto sapere sulla instabilità delle strutture (ma non avete mai osato chiedere)
No full textUna struttura inflessa può diventare instabile se soggetta a carichi morti di trazione?
L’instabilità di flutter in una struttura può essere indotta da un vincolo attritivo alla Coulomb
Surprising Instabilities of Simple Elastic Structures
No full textExamples of structures buckling in tension are presented, where no compressed elements are present, slightly different from those previously proposed by the authors. These simple structures exhibit interesting postcritical behaviours, for instance, multiple configurations of vanishing external force are evidenced in one case.
Flutter instability as induced by dry friction is also considered in the Ziegler pendulum, with the same arrangement introduced by Bigoni and Noselli (2011), but considering now the dynamical effects due to the mass of the wheel, which was previously neglected. It is shown that, for the values of rotational inertia pertinent to our experimental set-up, this effect does not change the overall behaviour, so that previous results remain fully confirmed
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
Effects of the constraint's curvature on structural instability: tensile buckling and multiple bifurcations
No full textBifurcation of an elastic structure crucially depends on the curvature of the constraints against which the ends of the structure are prescribed to move, an effect that deserves more attention than it has received so far. In fact, we show theoretically and provide definitive experimental verification that an appropriate curvature of the constraint over which the end of a structure has to slide strongly affects buckling loads and can induce: (i) tensile buckling; (ii) decreasing- (softening), increasing- (hardening) or constant-load (null stiffness) postcritical behaviour; and (iii) multiple bifurcations, determining for instance two bifurcation loads (one tensile and one compressive) in a single-degreeof- freedom elastic system. We show how to design a constraint profile to obtain a desired postcritical behaviour and we provide the solution for the elastica constrained to slide along a circle on one end, representing the first example of an inflexional elastica
developed from a buckling in tension. These results have important practical implications in the design of compliant mechanisms and may find applications in devices operating in quasi-static or dynamic conditions, even at the nanoscale
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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