1,720,954 research outputs found
Effect of Perfectly Aligned CNTS Under Cohesive Crack Bridging in Adhesive Joint
No full textRecent advances in nano-engineering have prompted the use of nanofillers to strengthen composites and adhesive joints. This is because of the phenomenal mechanical properties that these nanotubes possess. For example, carbon nanotubes have elastic modulus ~1 TPa, and tensile strengths of ~100 GPa, which are more than 300 times those of a polymeric material. It is the purpose of this project to quantify the exceptional effect of nanofillers in cohesive crack bridging in structural adhesive bonds (SABs) for the aircraft industry. In this study, we assume that the high aspect ratio nanotubes are perfectly aligned in a thermoset epoxy adhesive. We carried out finite element modeling of the nano-reinforced SABs taking into account the constitutive law of the nanofillers by using the atomistic-based continuum finite element model. A crack in the nanocomposite is propagated using the virtual crack closure technique and the resulting fracture toughness is calculated. The analysis was conducted using atomic-based continuum finite element in which the constitutive laws for the different phases were carefully selected. Specifically, the Lennard-Jones inter-atomic potentials were used to treat the nanotubes and continuum constitutive laws were used for the SABs. The model represents nanofillers pullout with nonlinear springs and the epoxy is modeled with 2D plane stress elements. Our work reveals that the introduction of perfectly aligned CNTs results in improvements in fracture toughness of the composite of up to 195% at 0.5 wt%. Increasing the weight percentage of carbon nanotube fillers was found to increase the fracture toughness almost linearly. The effect of alignment on the bridging phenomena yields significantly higher toughness values than those typically found experimentally, but this correlates well with studies regarding the effect of nanotube alignment
Effect of Perfectly Aligned CNTS Under Cohesive Crack Bridging in Adhesive Joint
No full textRecent advances in nano-engineering have prompted the use of nanofillers to strengthen composites and adhesive joints. This is because of the phenomenal mechanical properties that these nanotubes possess. For example, carbon nanotubes have elastic modulus ~1 TPa, and tensile strengths of ~100 GPa, which are more than 300 times those of a polymeric material. It is the purpose of this project to quantify the exceptional effect of nanofillers in cohesive crack bridging in structural adhesive bonds (SABs) for the aircraft industry. In this study, we assume that the high aspect ratio nanotubes are perfectly aligned in a thermoset epoxy adhesive. We carried out finite element modeling of the nano-reinforced SABs taking into account the constitutive law of the nanofillers by using the atomistic-based continuum finite element model. A crack in the nanocomposite is propagated using the virtual crack closure technique and the resulting fracture toughness is calculated. The analysis was conducted using atomic-based continuum finite element in which the constitutive laws for the different phases were carefully selected. Specifically, the Lennard-Jones inter-atomic potentials were used to treat the nanotubes and continuum constitutive laws were used for the SABs. The model represents nanofillers pullout with nonlinear springs and the epoxy is modeled with 2D plane stress elements. Our work reveals that the introduction of perfectly aligned CNTs results in improvements in fracture toughness of the composite of up to 195% at 0.5 wt%. Increasing the weight percentage of carbon nanotube fillers was found to increase the fracture toughness almost linearly. The effect of alignment on the bridging phenomena yields significantly higher toughness values than those typically found experimentally, but this correlates well with studies regarding the effect of nanotube alignment
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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