1,720,985 research outputs found
Large deformation non-linear response of fiber-reinforced elastomers: glass fibers-polydimethylsiloxane laminates
Full text linkSoft fibers-reinforced composites are promising materials for several applications as flexible actuators and in bio-mechanical devices. They are based on elastomeric polymers that allow ranges of deformation much larger than those of conventional thermosetting polymer-based composites. In order to investigate the behavior of these composites, quasi-static monotonic and cyclic tensile tests in uniaxial loading c onditions have been carried out on continuous glass fibers-polydimethylsiloxane laminates with stacking sequence [+θ,-θ]2S, with θ = 30, 45, 60 and 75°. The stress-strain curves obtained show a linear response of the materials at small strains, a “softened” response at intermediate strains and a strain induced “hardening” at large strains. An extensive fibers reorientation was observed during loading. Large reduction in the specimens width was also measured and an increase in their thickness was observed. Loading-unloading tests showed a pronounced hysteresis and strain induced softening was also observed. These experimental observations underline the importance of a deep characterization of elastomeric matrix composites
Fracture toughness of rubber in quasi-static conditions: How to experimentally obtain results intrinsic to the material?
Full text linkFracture toughness, defined as the energy dissipated to advance a crack by a unit area, is an intrinsic material property, which should not depend on the geometry and dimensions of the specimen used to obtain it. One of the most frequently used test configurations to determine rubber fracture toughness at crack initiation in quasi-static conditions is the single edge notched in tension specimen (SENT). The aim of this work is to quantitatively define the limitations of specimen dimensions needed to obtain an intrinsic value of fracture toughness for a nitrile-butadiene rubber (NBR), and to investigate the possible effects of the test procedure on the results. These show that a minimum width of 10 mm and a minimum height/width ratio of 4.6 are necessary to obtain a fracture toughness independent of specimen dimensions
Fracture behavior of filled elastomers: How do strain induced softening and its thermally induced recovery affect the fracture toughness?
Full text linkIn this work, two peroxide-crosslinked hydrogenated nitrile butadiene rubbers for hydrogen system applications have been studied. Both elastomers are carbon black filled and one of these also contains a small quantity of polyamide. At the beginning, a preliminary analysis of the strain rate effect on the mechanical response and of the strain-induced softening is reported. Moreover, the dissipated and stored energies involved in the deformation of both the virgin and softened materials are evaluated. The thermally induced recovery of the strain-softening is analyzed by performing two treatments. In the second part of the work, the fracture behaviour of the two materials is compared and the effects of softening and its thermally induced recovery on fracture behavior are evaluated on one of the two compounds. The main finding is that softened material has a lower fracture toughness compared to the virgin material, while toughness of the thermally treated softened material is comparable to that of the virgin one
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
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