1,721,042 research outputs found
Beyond Euler-Cauchy Continua. The structure of contact actions in N-th gradient generalized continua: a generaization of the Cauchy tetrahedron argument
No full textEdge contact forces and quasi-balanced power
No full textInternational audienceWe consider continuous media in which contact edge forces are present. Introducing the notion of quasi-balanced contact force distribution, we are able to prove the conjectures by Noll and Virga [1] concerning the representation of contact edge forces. We generalize the Hamel–Noll theorem on the Cauchy postulate. Then we adapt the celebrated tetrahedron construction of Cauchy in order to obtain a representation theorem for stress states. In fact, we show that two stress tensors of order two and three are necessary for such a representation. Moreover we find the relationship between the notion of interstitial working introduced by Dunn and Serrin [2] and the notion of contact edge forc
The relationship between edge contact forces, double forces and interstitial working allowed by the principle of virtual power
No full textInternational audienceWe consider continuous media in which contact edge forces are present. Introducing the notion of quasi- balanced contact force distribution, we are able to prove the conjectures made in [Noll, 1990] concerning the representation of contact edge forces. We first generalise the Noll theorem on Cauchy postulate. Then we adapt the celebrated Cauchy tetrahedron construction to find a representation theorem for stress states. Moreover we find the relationship between double forces Germain [Germain, 1973a,b], interstitial working [Dunn, 1985] and contact edge forces
The obstacle problem in masonry structures and cable nets
Full text linkWe consider the problem of finding a net that supports prescribed forces
applied at prescribed points, yet avoids certain obstacles, with all the
elements of the net under compression (strut net) or under tension (cable web).
In the case of masonry structures, for instance, this consists in finding a
strut net that supports the forces, is contained within the physical structure,
and avoids regions that may be not accessible due, for instance, to the
presence of holes. We solve such a problem in the two-dimensional case, where
the prescribed forces are applied at the vertices of a convex polygon, and we
treat the cases of both single and multiple obstacles. By approximating the
obstacles by polygonal regions, the task reduces to identifying the feasible
domain in a linear programming problem. For a single obstacle we show how the
region available to the obstacle can be enlarged as much as possible
in the sense that there is no other strut net, having a region
available to the obstacle with . The case where some of
the forces are reactive, unprescribed but reacting to the other prescribed
forces, is also treated. It again reduces to identifying the feasible domain in
a linear programming problem. Finally, one may allow a subset of the reactive
forces to each act not at a prescribed point, but rather at any point on a
prescribed line segment. Then the task reduces to identifying the feasible
domain in a quadratic programming problem.Comment: 22 pages, 12 figures, 3 supplemental video
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
- …
