1,721,334 research outputs found
Effects of mineral fillers on bitumen mastic chemistry and rheology
No full textAge hardening of bitumen is one of the key factors determining the lifetime of an asphalt pavement. This study attempts to investigate the effect of different fillers including hydrated lime on mastic ageing. The Thin Film Oven Test (TFOT) was used for short-term ageing, and the Pressure Ageing Vessel (PAV) was used to simulate long-term ageing. The changes due to the ageing are measured by the changes in complex modulus |G*| of the mastics. Chemical changes in the binder were evaluated by the means of Fourier Transform Infrared Spectroscopy (FTIR). Results indicated that different filler mineralogy and properties can significantly affect the rate of oxidative ageing, and this depends mainly on the filler type and concentration. It also showed that hydrated lime reduces the hardening rate more than limestone and granite filler and this correlated with the chemical changes measured by FTIR in terms of rate of change of the carbonyl oxidative products
Comparison between bitumen modified with crumb tyre rubber and styrene butadiene styrene
No full textThe improvements in terms of mechanical properties due to the use of polymers
to modify bitumens in road paving applications have already been widely demonstrated. The
aim of this paper is to show how the rheology and the performance of a bituminous binder
mixed with crumb rubber recycled from used tyres (CR-MB), could be comparable with a
styrene butadiene styrene (SBS-MB) created with the same base binder and currently used for
road applications. Physical, chemical and performance characterization followed by rheological
and storage stability analyses have been undertaken as the basis for the comparison. The results
of the investigation indicate that the blended CR-MB shows large improvements with respect to
the base bitumen, comparable with the SBS-MB under almost all the conditions. However, in
order to use this binder for practical purposes, major work regarding the improvement of the
storage stability of the CR-MB still needs to be done
Comparison between various bituminous binders modified with crumb tyre rubber
No full textThe aim of this paper is to show how the rheology, the performance and the storage
stability of different bituminous binders, obtained from two bitumens with different
asphaltenes content, change their properties when they are modified with recycled tyre crumb
rubber. Physical, chemical and performance characterisation followed by rheological and
storage stability analyses have been undertaken as the basis for the comparison. The results
of the investigation indicate that bitumen with lower asphaltenes content is more influenced
by the modification with the rubber. However, the modification of the bitumen with the higher
asphaltenes content gives a binder with better performance and storage stability. Moreover,
results shows that the addition of a certain amount of oil extender to the bitumens reduces the
effect of the modification and has no positive effect on storage stability
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
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