1,720,954 research outputs found
Fracture behaviour of polymers toughened with CaCO₃ nanoparticles
No full textThe objective of this PhD thesis is to develop new tough and rigid
nanocomposites based on polypropylene (PP) and polystyrene (PS) which are two
of the polymers with the highest demand and growth rates worldwide. Recently,
attempts have been made to improve the mechanical properties and
processability of PP and PS through several procedures. Nowadays the market
of fillers for polyolefines is dominated by calcium carbonate which is one of
the most widely used particulate fillers for polymer applications due to it’s
low cost, ready availability and useful properties. However, even if CaCO₃
enhances the Young’s modulus it is often reported that decreases impact
strength. Thus, researchers are studying to improve the mechanical properties
of polymers toughened with CaCO₃ nanoparticles so they are expected to be
very desirable materials. In fact, previous results from our work in
collaboration with Solvay Advanced Functional Minerals have shown that a
dry-coated PCC substantially enhances impact in both homopolymer and
copolymer iPP and so this result encourage us to continue these studies and
to extend its use on both PP and PS. So we studied the possibility to tough
some polyolefines mixed with different type of CaCO₃ nanoparticles (PCC) and
the mechanism that explains their mechanical deformation. In this way we
tested the effect of the different characteristics of the powders on the
final properties of the nanocomposites, as the various particles differ for
shape, granulometric size, surfactant agent and kind of process utilized to
prepare them.
This work is divided into three main parts: the first regards the fracture
behaviour of polyproylene filled with different kinds of CaCO₃ powders, the
second the development of a new alternative procedure to produce
nanocomposites (based on PP and PS matrices) with the relative comparison
with the extrusion method and the third the interface characterization with
various techniques
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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