1,720,955 research outputs found
Microstructural modelling of fatigue in layered bearing architectures
Full text linkSmall automotive plain engine bearings are used to provide the relative motion between the engine block and the crankshaft via the connecting rod. Under rapidly changing engine loads, these bearings may suffer fatigue damage during service. In modern multilayered bearing designs, fatigue resistance is a complex function of engine loading coupled with the layer architecture and a multiphase lining alloy. This research has mostly focussed upon micro-scale fatigue damage initiation on thin (0.2-0.3mm thickness) lining surface and its subsequent growth leading towards gross failure. The systems examined comprise Al alloys and sintered bronze as relatively soft and conformable lining layers. The weight percent composition of Al lining alloy was Al-6.5Sn-2.5Si-1Cu-1Ni-0.25Mn roll bonded to a stiffer and thicker backing steel layer (1.5-1.8mm thick) via an even thinner Al foil (0.04mm) as an interlayer. The other system comprised an Al lining (Al-20Sn–1Cu) alloy spray coated on to a medium carbon steel layer in the form of a flat bar. All these systems were compared with the previously investigated Al based designs with lining compositions: Al-12Sn-4Si-1Cu and Al-20Sn-1Cu-0.25Mn (manufactured by roll bonding processes). The performance evaluation was based upon the investigation of microstructural features involved in early fatigue initiation and their effect upon short crack growth on the surface. Subsurface crack growth through the layers has also been assessed and finally the observed fatigue life of various components linked to these behaviours. A 3-point bend test configuration was adopted for laboratory fatigue tests. Fatigue comparison was made on the basis of lining surface plastic strain amplitude vs. number of cycles to failure according to a uniform predefined criterion for all the systems. Maximum plastic strains developing at the lining surface were estimated using a combination of finite element analysis (FEA) and strain gauge measurements so that the fatigue life of all systems studied was presented as strain-life data. Specimens in the form of both finished bearings and flat bars were tested. Similar fatigue behaviour was observed for the two testing geometries, giving greater confidence in the fatigue evaluation process and allowing detailed observations of small crack initiation and growth processes in flat bars to be related to behaviour of the actual bearing geometry.
In the previous research, the coarser Si particles in the Al-12Sn-4Si-1Cu lining and Sn particles in the Al-20Sn-1Cu-0.25Mn alloys were identified as potential crack initiation sites, though the relationship between particle geometry and arrangement/clustering was found to be important. The newly developed Al-6.5Sn-2.5Si-1Cu-1Ni-0.25Mn lining alloy with finer and fewer Sn and Si particles showed a delayed initiation of short fatigue cracks compared to the previous systems. However, a large number of widely scattered intermetallics in the new linings were observed to fracture causing early fatigue initiation at the micro-scale level with some more complex processes of detaching Sn layers from harder intermetallics and Si particles. Using the mechanical property data for bulk lining and secondary phase particles obtained from tensile testing and instrumented hardness testing, stress fields were investigated within the hard particles (intermetallics), surrounding thin layers and the matrix on the basis of the analytical and numerical modelling. On the basis of these modelling results, optimum particle shapes were defined to minimize tensile stresses (within the particles) and hydrostatic stresses (at the particle matrix interfaces). The experimental growth data of a dominant crack when combined with a Hobson type growth model based upon measured particle distributions and experimental crack growth rates, helped in predicting fatigue life of a similar component at different stress levels. Surface crack driving force reduces considerably when subsurface crack deflection occurred within softer Al interlayer. Replacing this interlayer with a harder brazed sheet did not give any significant difference in the observed fatigue life. In the HVOF systems, crack initiation was observed to be from the weaker interface between a harder matrix and softer circular unmelts as well as from various scattered pores. The overall fatigue life of the HVOF systems was comparable to the previous roll bonded systems; however subsurface deflection of crack at the lining-backing interface resulted in the debonding of the lining and hence the observed lining fatigue resistance may not be a good indication of the overall performance in a bearing system.
At similar lining surface plastic strain levels, the bronze bearing with very thin Sn and Ni as overlay layers (~7 microns each) showed comparable fatigue resistance to the currently investigated RB Al based designs. However annealing this system resulted in the formation of hard Ni3Sn intermetallics at the Sn-Ni interface, and the observed fatigue resistance of this system was higher than the RB systems. This has been linked to very fine scale local crack deflection in the overlay layers (although these have not been observed clearly).
All these layered bearing systems provide a complex fatigue problem. Factors which reduce initiation /early growth behaviour are likely to offer the best service performance enhancements in view of the relatively HCF nature expected in service
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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