1,721,317 research outputs found
Effective implementation of a time discontinuous Galerkin method for non-linear structural dynamics
No full textIn the last years much research has been devoted to developing accurate and robust time integration
methods for non-linear structural dynamics. To this end, filtering out the unwanted high-frequency
response has been recognized as a desirable feature and various attempts have been made to
introduce such a dissipative feature (see [1] and the references therein, amongst other). An attractive
approach is offered by the time discontinuous Galerkin (TDG) method, which has been successfully
applied to linear and non-linear structural dynamics, owing to its good stability and accuracy
properties (see for example [2,3]). Although it properly combines higher order accuracy and
high-frequency dissipation, standard implementations turn out to be much more expensive than
classical algorithms, since a larger system of equations should be solved at each time step. Thus,
developing effective implementations plays a key role in the practical applicability of the method.
The purpose of this work is to establish an efficient iterative procedure to implement the TDG
method based on piecewise linear time interpolation for non-linear dynamics. This is achieved by
generalizing the algorithm proposed by the authors in [3] for linear problems. The solution strategy is
rather different from previous efforts, which are essentially based on conventional iterative schemes
(such as Gauss-Jacobi or Gauss-Seidel scheme). In particular, the present procedure is based on an
implicit predictor-two-corrector scheme, designed to search for the TDG solution while preserving
the TDG stability and dissipative properties at each iteration. Improving accuracy is demanded to
iterative corrections. The proposed procedure is simple and offers several advantages. Remarkable
computational savings are achieved, since iterative corrections are performed using an effective
stiffness matrix, as it occurs in standard algorithms. In linear regime, no more than two iterations are
needed to obtain the same overall accuracy of the TDG method. Moreover, the algorithm can be
easily implemented into existing finite element codes. Numerical tests confirm the attractiveness of
the present procedure, which appears to be competitive with commonly used algorithms and
available TDG implementations.
REFERENCES
[1] D. Kuhl, M. A. Crisfield, Energy conserving and decaying algorithms in non-linear structural
dynamics, Int. J. Numer. Meth. Engng., 45, (1999), 569-600.
[2] N. E. Wiberg, X. D. Li, Adaptive finite element procedures for linear and non-linear dynamics,
Int. J. Numer. Meth. Engng., 46, (1999), 1781-1802.
[3] M. Mancuso, F. Ubertini, An efficient integration procedure for linear dynamics based on a time
discontinuous Galerkin formulation, Comput. Mech., 32, (2003), 154-168
An efficient time discontinuous Galerkin procedure for non-linear structural dynamics
No full textThis paper presents an effective time discontinuous Galerkin procedure for non-linear dynamics. The procedure is based on a cheap iterative algorithm, which is rather different from previous efforts. In fact, the algorithm is designed so that the corrected solutions inherit the desired stability and dissipative properties and the iterations serve only to improve accuracy. Some numerical tests illustrate the good performance of the present procedure, which appears to be competitive with the available implementations of time discontinuous Galerkin methods
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
A practical perspective on next generation metro architectures and protocol stack developments
No full text
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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