1,720,955 research outputs found
Atmospheric pressure plasma surface engineering to improve polymer matrix composite bonding
No full textNichols, John - Associate Supervisor
See, Tian-Long - Associate SupervisorThis thesis explores the improvement of adhesive properties on carbon fibre
reinforced epoxy composites, specifically MTM44-1, through the application of
atmospheric pressure plasma (APP) treatments. The study aims to address the
critical challenge of enhancing the adhesion of composite surfaces by
investigating both thermal and non-thermal plasma techniques. A comprehensive
analysis of plasma treatment uniformity, temperature effects, and treatment
speeds has been conducted.
Special emphasis is placed on the removal of silicone contamination, from mould
release agents, a common barrier to effective adhesion. Current industrial
approaches often struggle to fully eliminate silicone contamination, which
severely limits adhesive bonding on composite surfaces. Plasma has the
potential to remove silicone contamination, while also improving the surface
energy, prior to adhesion.
Another consideration in this study has been to the speed of plasma treatment.
One of the barriers to using adhesion to bond composites in the industry is the
time it takes to pre-treat surfaces prior to adhesion.
This study aims to also investigate the relationship between treatment time and
surface energy, especially as APP can be easily integrated into a manufacturing
processes, compared to traditional plasma surface treatment. This is due to the
lack of vacuum which saves time, space and often energy in the process.
Various plasma generation methods were explored, including microwave, radio
frequency (RF), and Dielectric Barrier Discharge (DBD), to treat the composite
surfaces. This allowed for a variety of different plasma feed gases to be used
including nitrogen, argon and a mixture of fluorinated gas and argon.
Surface characterisation was conducted using X-ray photoelectron spectroscopy
(XPS) to assess the chemical composition of the treated surfaces, while water
contact angle (WCA), surface energy measurements and lap shear testing were
used to evaluate the effectiveness of the treatments in promoting adhesion. The
results demonstrate that plasma treatments significantly enhance the surfaceii
energy of the composites by removing surface contaminants, particularly silicon
containing release agents, while also altering the surface chemistry to promote
better adhesive bonding.
The work also evaluates the impact of processing parameters such as treatment
speed and gas flow rates on surface modification efficiency and surface
temperature, particularly when considering thermal radio frequency (RF) plasma.PhD in Manufacturin
In process temperature monitoring of energy beam processing.
Full text linkThe use of non-thermal and atmospheric plasma has been growing in recent
years. Applications in wound sterilisation, food decontamination, cleaning and the
more traditional machining and deposition are just some of the areas in which
new technology is being developed. With the growing use of cool plasma comes
the requirement to test and understand the temperature distribution of the jets.
Current methods into temperature measurement revolve around spectroscopy
and other non-contact methods. Spectroscopy can pose a challenge as a
measurement device as it lacks the ability to measure overall gas temperatures
in non-thermal plasmas. Contact measurement thermometers, such as
thermocouples and resistance temperature detectors are an alternative which
can provide an insight into the temperature of the ions and neutral species.
However these sensors pose a challenge in gaining accurate or precise
temperature measurements due to their susceptibility of electromagnetic
interference.
Fibre Bragg grating sensors have the ability of measuring both temperature and
strain without electromagnetic interference. They possess the ability of
multiplexing, being able to measure multiple temperatures across a single fibre,
which can aid in measuring over a long distance. They also have the added
benefit of being small, lightweight and have quick thermal response times.
Additionally their small heat capacity reduces the effect on the temperature of the
measurand, improving their accuracy over other physical probes. In this
experiment fibre Bragg grating sensors 600 μm and 1000 μm in length and 10μm
in diameter have been used to characterise the temperature distribution of non-
thermal microwave plasma and thermal radio frequency plasma jets.
Thermocouples have been used to compare results against current technologies.
Results show the fibre Bragg grating sensors have been successful in
determining plasma temperature changes over time, distance and across a
variety of different parameters.PhD in Manufacturin
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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