1,721,162 research outputs found
Numerical Methods for the Modelling of Debonding in Composites
No full textThis monograph starts with a discussion of various phenomena in laminated composite structures that can lead to failure: matrix cracking, delamination between plies, and debonding and subsequent pull-out between fibres and the matrix material. Next, the different scales are discussed at which the effect of these nonlinearities can be analysed and the ways to couple analyses at these different length scales. From these scales—the macro, meso and micro-levels — the meso-level is normally used for the analysis of delamination, which is the focus of this monograph. At this level, the plies are modelled as continua and interface elements between them conventionally serve as the framework to model delami-nation and debonding. After a brief discussion of the cohesive—zone concept and its importance for the analysis of delamination, a particular finite element model for the plies is elaborated: the solid—like shell. This is followed by a derivation of interface elements. In the second part of this monograph more recent methods to numerically model delamination are discussed: meshfree methods, methods that exploits the partition—of—unity property of finite element shape functions, and discontinuous Galerkin methods. These approaches offer advantages over the more traditional approach that uses interface elements, as will be discussed in detail. From these more modern discretisation concepts the partition-of-unity approach seems the most promising for modelling debonding in composite structures, one advantage being that it can rather straightforwardly be incorporated in solid-like shell elements, thus enabling large-scale analyses of layered composite structures that take into account the possibility of debonding
Variational Germano approach for multiscale formulations
No full textIn this chapter the recently introduced Variational Germano procedure is revisited. The procedure is explained using commutativity diagrams. A general Germano identity for all types of discretizations is derived. This relation is similar to the Variational Germano identity, but is not restricted to variational numerical methods. Based on the general Germano identity an alternative algorithm, in the context of stabilized methods, is proposed. This partitioned algorithm consists of distinct building blocks. Several options for these building blocks are presented and analyzed and their performance is tested using a stabilized finite element formulation for the convectionU? diffusion equation. Non-homogenous boundary conditions are shown to pose a serious problem for the dissipation method. This is not the case for the leastsquares method although here the issue of basis dependence occurs. The latter can be circumvented by minimizing a dual-norm of the weak relation instead of the Euclidean norm of the discrete residual
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
Higher-order damage models for the analysis of fracture in quasi-brittle materials
No full textHigher-order continuum descriptions invariably introduce one or more additional material parameters. An experimental problem resides in the determination of these additional parameters. In the present contribution two materials are examined and the relation between the internal length scale and the observed experimental results is examined. A gradientenhanced damage model is used for concrete, while a strain-based transient gradient damage (STGD) method is used to describe the behaviour of SGFPP. In the STGD-model, the unloaded material is modelled in a strictly local way, and the nonlocal effect increases with the local strain state of the material. This method leads to a well-defined crack opening and converges to a damaged zone with a finite width which does not broaden during crack propagation. The convergence upon mesh refinement with this method is adequate. In the case of SGFPP, the experimental results obtained from the Compact-Tension tests have been used to make a local comparison with the computational results obtained with the STGDmethod. The parameters in the model are quantified and the proper modelling of the size and notch effects are investigated
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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