1,720,986 research outputs found
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
Design, analysis, and optimisation of discontionuous tailorable composites
Get PDFComposite materials are an attractive material for use in the aerospace and automotive sectors, due to their high specific strength and specific stiffness. However, most composites fail suddenly in a brittle manner, which may result in catastrophic failure. This inherent lack of tailorability in the mechanical response of composites has made their widespread application limited.
Aligned discontinuous composites (ADCs) are a new type of material that offers increased mechanical tailorability, as subtle changes to the ADC microstructure can change its stress-strain response from high-strength linear elastic behaviour, to a non-linear response with high levels of pseudo-ductility. This work aims to understand mechanisms for mechanical tailorability in ADCs, and determine the suitability of ADCs for applications in real-world structures.
A Virtual Testing Framework (VTF) is used and developed throughout this thesis, to give an in-depth understanding of the behaviour of ADCs. The VTF consists of a multiscale framework to simulate complete ADC specimens with hybrid or non-hybrid reinforcement; final failure of ADCs is simulated in the VTF by a non-linear fracture mechanics failure criterion. The VTF is successfully validated throughout this thesis against a variety of experimental data with good agreement.
The first study explores the use of different hybrid fibre-type arrangements, to explore their influence on the pseudo-ductile behaviour of hybrid ADCs. The addition of a fibre-migration algorithm (used to capture the effects of fibre movement in ADCs during their manufacture), and developments to the fracture-based failure criterion, enable the VTF to successfully capture the effects of various levels of fibre-type grouping. Hybrid ADCs with larger groups of low-elongation fibres demonstrate a more brittle response, whereas intimate intermingling of the fibre-types increases pseudo-ductility. The ultimate strength and pseudo-ductility are then maximised by employing a fibre-type arrangement where the low-elongation fibres are completely isolated from one-another.
Having shown variability in the fibre-type arrangement has a significant influence on tailorability, the concept of variability is explored further. Several new sources of variability and defects are added to the VTF, and the non-linear fracture-based failure criterion is further improved to accurately predict the failure of any type of ADC microstructure. The VTF indicates that the most critical source of variability (i.e. the source of variability that most readily promotes premature failure) depends on the microstructural design of the composite: hybrid-fibre ADCs are most sensitive to the fibre-type arrangement, while short-fibre non-hybrid ADCs are most sensitive to variability in the fibre overlap lengths, and long-fibre non-hybrid ADCs are more sensitive to weaker fibres.
The VTF is then coupled with an intelligent optimisation routine to maximise the mechanical performance of ADCs that feature inherent variability. The use of a surrogate model helps minimise the number of design iterations before optimal design(s) are converged upon; surrogate modelling is also demonstrated to be invaluable when assessing the optimality of materials which feature high levels of inherent variability (such as ADCs). The true tailorability of ADCs is showcased, with an initial stiffness of 505 GPa, an ultimate strength of 1.92 GPa, or an ultimate strain of 3.92 % all achievable in ADCs via single-objective optimisation. While significant trade-offs between competing mechanical performance characteristics are found, useful combinations of mechanical properties remain, with an optimal ultimate strength & ultimate strain combination of 982 MPa and 3.27 %, or an optimal combination of 720 MPa yield strength & 1.91 % pseudo-ductile strain all possible.
ADCs are shown throughout this thesis to fail by translaminar fracture, yet the resistance of ADCs to translaminar cracks has never been measured; the translaminar fracture toughness is therefore a key material property that must be characterised, to enable accurate failure predictions using the VTF, and to enable the use of ADCs as part of a damage tolerant structure. Specially-designed compact tension tests are performed to measure the translaminar fracture toughness of hybrid and non-hybrid ADCs for the first time in literature. Results show that the translaminar fracture toughness of non-hybrid ADCs is significantly higher than hybrid ADCs, and that analytical predictions of the translaminar fracture toughness are sufficiently accurate to ensure realistic failure predictions using the VTF.
The new understanding and optimisation of aligned discontinuous composites demonstrates the feasibility of ADCs as an alternative material for the aerospace and automotive sectors. The models developed as part of this study can be used to support the design of new materials, perform parametric studies, and perform intelligent optimisation campaigns.Open Acces
Electrochemical processing of carbon nanotubes
Get PDFElectrochemical methods are highly versatile and useful ways to process single-walled carbon nanotubes. Individualised carbon nanotube solutions can be obtained by reductive charging, using a simple three-electrode system, thereby eliminating the need for damaging ultrasonication, non-scalable ultracentrifugation or the use of undesired surfactants. The electrochemical dissolution methods were also useful towards the purification of carbon nanotube fibres, where unwanted amorphous carbon and shorter nanotubes selectively dissolved, hence leaving behind the preferred longer nanotubes. With a suitable electrolyte system, oxidative charging can be used to perform similar dissolutions, where nanotube cations were obtained. Nanocarbon anions and cations, obtained through these electrochemical charging methods, can be readily grafted with functional side-chains. Traditionally, the grafting of nanocarbon anions is performed by a two-step process of chemically-reducing the nanocarbon to a defined charge to carbon ratio, followed by the addition of grafting agents. In comparison, electrochemical charging methods are continuous and thereby offer clear advantage over the traditional chemical methods, where redox active agents may be depleted and require replenishment. The electrochemical grafting of redox-active ferrocene on nanotube has further allowed an accurate and non-destructive determination of grafting ratio with cyclic voltammetry, which is preferred over thermogravimetric methods that are prone to over-estimations. In another part of this work, pre-solubilized carbon nanotube ions were electrochemically deposited onto an electrode surface through selective ion discharge, thereby demonstrating the full versatility of electrochemical processing methods.Open Acces
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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