1,720,957 research outputs found
The synergistic effects of cavitation erosion-corrosion in ship propeller materials
Get PDFSynergy tests were performed for two most common propeller materials, duplex stainless steel (DSS) and nickel aluminium bronze (NAB), by means of an indirect ultrasonic vibratory system. Tests were conducted for pure cavitation erosion in distilled water, pure corrosion using in situ electrochemistry under 3.5 % NaCl solution and a combination of cavitation erosion–corrosion to understand the overall synergism existing between the two. The results were analysed using gravimetric as well as volumetric analysis. Alicona and Talysurf were employed for the surface topography, and scanning electron microscope was used to see the microstructural morphologies of the samples under different conditions. As a result, the electrochemical tests held at open circuit potential showed that, although DSS exhibited higher resistance to corrosion under seawater alone, NAB exhibited much higher resistance to corrosion when subjected to cavitation. From the experiments conducted, it was concluded that synergy had measurable impact on the cavitation erosion–corrosion of both NAB and DSS. NAB was found to be more susceptible to erosion under both the conditions as compared to DSS with prominent selective cavitation erosion of alpha phase in the microstructure. The overall synergism of NAB was found to be higher than that of DSS
Investigation of cavitation erosion-corrosion of duplex stainless steel and nickel aluminium bronze in 3.5% nacl solution
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Energy-related tribo-corrosion research at the National Centre for Advanced Tribology at Southampton
No full textThis paper is based on a keynote lecture given at the Third International Conference on Tribo-Corrosion, sponsored by ASTM International and held at the Georgia Institute of Technology, Atlanta, GA, April 19–20, 2012. It summarises the tribo-corrosion-related research relevant to the energy sector that has taken place over the past 30 years at the National Centre for Advanced Tribology at Southampton at the University of Southampton in the United Kingdom. Research is presented that relates to multiple components in energy generation/conversion systems and involves a wide range of tribo-corrosion mechanisms. These include cavitation erosion–corrosion of turbomachinery, abrasion–corrosion of downhole drilling equipment, erosion–corrosion of nuclear slurry handling components, bearing degradation of renewable energy systems (wind turbines), erosion–corrosion in nuclear power plants (Berg, H.-P., “Corrosion Mechanisms and Their Consequences for Nuclear Power Plants with Light Water Reactors,” Reliability and Risk Analysis: Theory and Applications, Vol. 2, 2009,pp. 57–68), erosion–corrosion in non-renewable energy systems (oil and gas), and tribochemical processes in internal combustion engines. Work from other research groups is also used to show the importance of understanding tribo-corrosion in energy generation/conversion systems
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
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