1,721,560 research outputs found
Dynamics of Multibody Systems in Space Environment; Lagrangian vs. Eulerian Approach
No full textThe paper describes the motion of a multibody in space environment: by space environment we mean space-varying gravity, gradient forces, control forces, if any. . Two different formulation have been outlined, compared and discussed,Comparison of the two approaches shows perfect agreement (as one should have expected), since they are both exact models referring to the same physical system. In general, however, the Eulerian approach lends itself to a better understanding of physical facts, in particular, of the entity of the reactions and of the corresponding structural stresses
Structural Dynamics of Cantilever Wing-Like Anisotropic Swept Plate
No full textThe general equation for a cantilever swept anisotropic plate (simulating a swept wing) is written in terms of chordwise expansion in a complete set of functions. This leads to a system of ordinary differential equations in η, the spanwise coordinate; the dynamic problem is considered leading to an expression which represents the most synthetic approach to many degrees of freedom torsion-bending interaction. Then methods of solution based on an analytical approach and spanwise finite element solution are described. Numerical examples show the effect of sweep and anisotropicity on frequencies and modes
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 finite-gap method and the periodic NLS Cauchy problem of anomalous waves for a finite number of unstable modes
No full textThe focusing non-linear Schrodinger (NLS) equation is the simplest universal model describing the modulation instability (MI) of quasimonochromatic waves in weakly non-linear media, and MI is considered to be the main physical mechanism for the appearance of anomalous (rogue) waves (AWs) in nature. In this paper the fnite-gap method is used to study the NLS Cauchy problem for generic periodic initial perturbations of the unstable background solution of the NLS equation (here called the Cauchy problem of AWs) in the case of a fnite number N of unstable modes. It is shown how the fnite-gap method adapts to this specifc Cauchy problem through three basic simplifcations enabling one to construct the solution, to leading and relevant order, in terms of elementary functions of the initial data. More precisely, it is shown that, to leading order, i) the initial data generate a partition of the time axis into a sequence of fnite intervals, ii) in each interval I of the partition only a subset of N (I) 6 N unstable modes are visible , and iii) for t ? I the NLS solution is approximated by the N (I)-soliton solution of Akhmediev type describing for these visible unstable modes a non-linear interaction with parameters also expressed in terms of the initial data through elementary functions. This result explains the relevance of the m-soliton solutions of Akhmediev type with m 6 N in the generic periodic Cauchy problem of AWs in the case of a fnite number N of unstable modes
- …
