1,720,955 research outputs found
Data supporting: Oxidation behaviour of single crystal nickel based superalloys: Intermediate temperature effects at 450-550oC
No full textThis data supports the following publication: Evangelou A., Soady K.A., Lockyer S., Gao N., Reed P.A.S.(2017), Oxidation behaviour of single crystal nickel based superalloys: Intermediate temperature effects at 450-550oC.
Abstract:
The oxidation behaviour of two commercially available single crystal nickel based superalloys has been investigated at the lower operating temperature range (450-550ºC) of an industrial gas turbine blade. Isothermal oxidation was carried out for varying times up to 640h and the low temperature exposure resulted in a sub-micron thick oxide. The external and internal oxide kinetics were studied via high resolution image analysis and both showed sub-parabolic growth rates. Thermogravimetric tests indicated that the overall oxidation growth obeys a near quartic power law while parabolic kinetics can describe the transient oxidation period. Characterisation of the resulting oxides was carried out using field emission gun scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Results from thermodynamic modelling (Thermo-Calc) of the oxide formation are also presented to further assess the postulated mechanism of low temperature oxidation in these nickel based superalloys.</span
On the mechanism of oxidation-fatigue damage at intermediate temperatures in a single crystal Ni-based superalloy
No full textThe combined effects of environment (oxidation) and mechanical load (fatigue) that control crack propagation in a single crystal Ni-based superalloy have been investigated with particular focus on the intermediate service temperature range. Fatigue tests have been carried out at different frequencies, hold times and environments, to study the parameters influencing crack propagation at 550 °C. The direct current potential drop method was used to monitor the crack growth while STEM-EDS were used to analyse the fracture mode and crack tip regions.It was found that the micro-mechanism of fatigue crack propagation at intermediate temperatures is a complex process with several competing mechanisms acting on the crack tip simultaneously. Crystallographic slip processes by γ′ shearing are active at these temperatures while at the same time thermally activated processes that promote crack propagation through the γ channels also take place. In addition, the effects of oxidation were found to be two-fold. It was demonstrated that these temperatures are not high enough to cause macroscopic embrittlement of the crack tip but finger-like protrusions were found to penetrate the material ahead of the crack tip at the nano-scale. The kinetics of such a mechanism were accentuated by the plastic strains at the crack tip, which given enough time, can promote cleavage fracture at the γ/γ′ interface. At the same time, given that the crack driving force is lower than a transition value, oxide formation on the crack tip surfaces can bridge the opening of the crack tip and reduce the effective driving force
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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