1,720,954 research outputs found
Finite element and analytical modelling of roughness induced fatigue crack closure
No full textThe incidence of roughness induced fatigue crack closure has been studied by finite element and analytical modelling. Results of the finite element model under constant amplitude show: (1) an increasing effect of crack deflection angle on crack closure levels, consistent with the simple geometrical model of Suresh and Ritchie, and (2) little dependence of crack closure levels on the value of the ratio of asperity size to the crack tip plastic zone above a certain critical value. From the finite element model results an important new mechanism to explain the origin of roughness induced crack closure has been proposed, arising from the residual shear deformation of the asperities. This new mechanism has been considered in relation to the conventional description of roughness induced crack closure, in which a global shear offset of the fracture surfaces is required. In particular, problems with the conventional roughness induced crack closure mechanism have been discussed.An analytical model based on the proposed closure mechanism has been constructed using standard fracture mechanics expressions. The results of the analytical model are shown to be consistent with the finite element results. The model is considered particularly valuable in: (1) showing that the novel micromechanistic understanding derived from the finite element modelling is consistent with well established fracture mechanics descriptions of crack behaviour, and (2) providing a simple analytical description of RICC, without introducing any arbitrary crack shear parameters. The model has been shown to be consistent with the experimental crack closure behaviour typically exhibited by damage tolerant aluminium aerospace alloys.</p
Some issues on finite element modelling of plasticity induced crack closure due to constant amplitude loading
No full textAn investigation of plasticity induced crack closure (PICC) behaviour using finite element (FE) method is presented for cracks subjected to constant amplitude loading and small scale yielding (SSY) conditions. Undeflected cracks have been examined under both plane strain and plane stress conditions. Anomalous near-tip closure in FE models has been identified to occur under both plane stress and plane strain conditions and is seen to vary with baseline load levels and crack propagation algorithms. In the case of plane strain models, propagation algorithms are seen to influence pre-crack closure. In general terms it may be said that none of the plane strain models showed crack closure that could be related to ongoing/steady-state crack growth: crack closure in all cases was dominated by pre-crack contact, and/or anomalous near-tip contact, even for the relatively long crack propagation used in the low loading range models
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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