1,721,059 research outputs found
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
Chicken Feather Fibre Mat/PLA Composites for Thermal Insulation
No full textIn order to add more economic value to chicken feather, a waste material of the poultry industry, it has been researched to incorporate chicken feather fibre (CFF) into resin to produce value-added composites. In the present research, chicken feather fibre was separated from the rachises and used to produce fibre mats. Then fibre mats were incorporated into polylactic acid (PLA) to make composites with low thermal conductivity. The procedure for making chicken feather fibre mat using an automatic dynamic sheet former was explored. Two different composite fabrication methods were investigated. One involved fabricate composite samples by hot pressing chicken feather fibre mats with PLA sheet. The other involved making composite specimens by hot pressing PLA powder and chicken feather fibre mats. A decrease in tensile strength compared to PLA had been expected before composite specimen fabricating according to previous research and so alkali treated fibre mats were used to improve tensile strength of composites.
It was concluded that chicken feather fibre mats with uniform quality could be made by controlling the jet-to-spin ratio and water wall thickness of the dynamic sheet former cylinder. Stable mat/PLA composites could be fabricated by hot pressing chicken feather fibre mats with PLA powder. Results from tensile testing indicated that alkali treatment could improve tensile strength to a small degree. SEM image analysis revealed that poor interfacial bonding between fibre barbs and PLA matrix had occurred. Thermal conductivity testing demonstrated improved thermal insulation with addition of CFF to PLA
The Effect of Heat Treatment on the Structure and Properties of Hemp/PLA Composites
No full textThis project focuses on bio-derived composites made from poly(lactic acid) (PLA) and hemp as well as the influence of PLA crystallinity on material properties.
It is known that crystallinity can occur as spherulites within a polymer matrix bulk and as transcrystallinity on fibre surfaces in thermoplastic matrix composites. In addition, thermal history is known to influence the degree of crystallinity of polymer materials. The aim of this project was to study the effect of heat treatment or annealing on crystallinity and the influence of this on properties of hemp/PLA composites.
Composites were observed to become more opaque during heat treatment and increased crystallinity after heat treatment was seen using optical microscopy. XRD and DSC results showed that crystallinity was much higher for composites than PLA, supporting the fibre acting as a nucleating agent. There was no apparent change to tensile strength with increased heat treatment for PLA, however, for composite samples, increased heat treatment led to a small reduction in average tensile strength. Although there was no discernable trend for change of fracture toughness with increased crystallinity for PLA, it decreased for composite materials. It appears that the increased crystallinity present in the composite in combination with increased stress concentration due to the presence of fibres is reducing composite toughness as well as leading to premature failure in tensile tests due to PLA brittleness explaining lower strengths for composites. DMTA suggests that increase in crystallinity contributes to thermal stability of the composite
The viability of waste copper chromium and arsenic treated timber reinforced polypropylene as a sustainable building material
Full text linkThe aim of this thesis was to investigate the viability of wood-plastic composites (WPCs) produced from wood flour and fibre derived from waste copper chromium and arsenic (CCA) treated timber for use as a sustainable material in the construction sector.
The research included an assessment of mechanical properties and the leaching of heavy metals from the wood-plastic composites, and the results were compared to material requirements in the building sector provided through literature and New Zealand building standards. Mechanical and chemical methods were used to prepare wood flour and fibre samples from waste CCA treated timber for use in wood-plastic composites. Composites were produced through compounding using a twin screw extruder or a custom sigma blade compounder and then injection moulded for material testing. Composites produced using an extruder with 40 wt.% bleached fibres and 4 wt.% MAPP, increased tensile strength (TM) from 18.5 MPa for the polypropylene used for the matrix to 27.6 MPa; Young's modulus (YM) was increased from 0.84 GPa to 2.33 GPa.
Comparison of mechanical performance with commercial WPC properties suggests that waste CCA treated timber could be used as a raw material to produce WPC for semi-structural applications. The modulus (2.33 GPa, in the highest performing composites) was roughly three times lower than commonly used commercial timbers used in structural applications. The creep performance was not measured for a time frame long enough to be indicative of the 50 years required for structural application. Therefore, further research is required to investigate whether the low modulus and creep performance of the WPC is acceptable for a structural material in the construction sector.
One of the largest concerns with using waste CCA treated timber as a reinforcement material in WPC was the inclusion of heavy metals and the potential for leaching. Arsenic was considered the most toxic of the heavy metals in the CCA treated timber. Processing of the waste CCA treated timber to obtain fibre was found to reduce arsenic concentration by up to 99.94 % in the best scenario. Furthermore, arsenic in leachate from composites was found to decrease from 41.29 to 0.07 ppb when comparing wood flour composites to digested and bleached fibre composites. The concentration of copper, chromium, and arsenic in leachate from composites produced with chemically obtained fibre was found to be significantly lower than the maximum allowable drinking levels in New Zealand. Therefore, indicating the application of composites produced with wood fibre from waste CCA treated timber can be regarded as safe even in scenarios that involve human contact with the material.
A life cycle analysis study found that the use of an alkali digestion process to obtain fibre significantly increased the environmental impact compared to the processing required to obtain wood flour. In a study of a potential commercial scale process, ultrasonic treatment and hydrogen peroxide bleaching as secondary fibre treatments were the largest contributors to environmental impact in the preparation of wood fibre. Thus, the results suggest that chemical treatments should only be employed to produce wood fibre when the highest mechanical performance or lowest leaching levels are required for the application of the wood-plastic composites
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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