1,722,575 research outputs found
Electrodeposition of nickel-based composite coatings for tribological applications
No full textThe purpose of this research is to study, evaluate, and compare the different electro deposition processes for producing nickel-based composite coatings for application in tribology, including: Ni/BMA luminescent coating, Ni-P/MoS2 and Ni-P/WS2 self-lubricating coatings. In the first part, a new luminescent Ni coating containing an embedded, blue emitting rare-earth mixed metal oxide (BaMgAl11O17:Eu2+) BAM was electrodeposited successfully from an aqueous electrolyte. Two types of surfactants were utilised to investigate the effective co-deposition of these phosphors into the nickel matrix. The surfactants of non ionic PEG (polyethylene glycol) and cationic CTAB (cetyl trimethylammonium bromide) were observed to increase the phosphor contents in the deposit from zero to 4.6% and 11.5%, respectively. A mixture of these two surfactants produced the highest particle embedded coverage (15.6%). Systematic study of the hardness, corrosion, tribological and luminescent properties of the as-deposited coating was performed before using it for wear sensing. In the second and third parts of this research, a self-lubricating Ni-P/MoS2 composite coating hasbeen designed and deposited on a mild steel substrate by electrodeposition. The effect of current density, electrolyte additive and MoS2 concentration on the structure of the coating have been investigated. The Ni-P/MoS2 coating exhibited a dramatic reduction in friction compared to an electrodeposited Ni-P coating, the coefficient of friction against a bearing steel ball in sliding wear being as low as 0.05. The worn surfaces and the wear debris were characterised by surface analysis techniques. The composite coating showed only slight wear and oxidation compared to the severe wear and oxidation observed in the pure Ni-P coating or the uncoated mild steel substrate. It has been speculated that MoS2 in the coating underwent shear stress-induced reorganization, fragmenting into fine crystallites and ultimately forming a smooth lubricating film.In the final part, Ni-P/WS2 composite coatings have been electrodeposited from an aqueous bath containing suspension of WS2 nanoparticles (80 nm) and their tribological properties have been evaluated by a reciprocating test with bearing steel balls. Increasing the bath temperature did completely eliminate the cracks in coatings by reducing the internal stress and prolonged the duration of the low friction coefficient. By optimizing the combinations of the WS2 and CTAB concentrations in solution, the amount of the WS2 particles incorporated was greatly boosted, demonstrating a highest WS2 content of 4.8 wt%. Significantly, this Ni P/WS2 coating exhibited a greatly lower friction coefficient of 0.17 compared to single Ni-P (0.6).<br/
Consensus with Max Registers
Full text linkWe consider the problem of implementing randomized wait-free consensus from max registers under the assumption of an oblivious adversary. We show that max registers solve m-valued consensus for arbitrary m in expected O(log^* n) steps per process, beating the Omega(log m/log log m) lower bound for ordinary registers when m is large and the best previously known O(log log n) upper bound when m is small. A simple max-register implementation based on double-collect snapshots translates this result into an O(n log n) expected step implementation of m-valued consensus from n single-writer registers, improving on the best previously-known bound of O(n log^2 n) for single-writer registers
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
Mileewa furcata Yu, He & Yang 2021
No full text17. Mileewa furcata Yu, He & Yang, 2021 Mileewa furcata Yu, He & Yang, 2021: 438. Type-locality. China (Xizang). Distribution. China (Xizang).Published as part of He, Hong-Li, Yan, Bin, Yang, Mao-Fa & Webb, M. D., 2021, Four new species of Mileewini leafhoppers (Hemiptera: Cicadellidae: Mileewinae) from China, with a checklist to Chinese species, pp. 521-540 in Zootaxa 4949 (3) on page 533, DOI: 10.11646/zootaxa.4949.3.5, http://zenodo.org/record/464062
Mileewa nigricincta Yu, He & Yang 2021
No full text36. Mileewa nigricincta Yu, He & Yang, 2021 Mileewa nigricincta Yu, He & Yang, 2021: 442. Type-locality. China (Xizang, Yunnan). Distribution. China (Xizang, Yunnan).Published as part of He, Hong-Li, Yan, Bin, Yang, Mao-Fa & Webb, M. D., 2021, Four new species of Mileewini leafhoppers (Hemiptera: Cicadellidae: Mileewinae) from China, with a checklist to Chinese species, pp. 521-540 in Zootaxa 4949 (3) on page 535, DOI: 10.11646/zootaxa.4949.3.5, http://zenodo.org/record/464062
Mileewa digitata Yu, He & Yang 2021
No full text12. Mileewa digitata Yu, He & Yang, 2021 Mileewa digitata Yu, He & Yang, 2021: 436. Type-locality. China (Xizang). Distribution. China (Xizang).Published as part of He, Hong-Li, Yan, Bin, Yang, Mao-Fa & Webb, M. D., 2021, Four new species of Mileewini leafhoppers (Hemiptera: Cicadellidae: Mileewinae) from China, with a checklist to Chinese species, pp. 521-540 in Zootaxa 4949 (3) on page 533, DOI: 10.11646/zootaxa.4949.3.5, http://zenodo.org/record/464062
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
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