1,720,977 research outputs found
CORRELATION BETWEEN CREEP AND TENSILE BEHAVIOUR IN LOW ALLOY STEEL
No full textStudent Number : 9800022T -
PhD thesis -
School of Mechanical, Industrial and Aeronautical Engineering -
Faculty of Engineering and the Built EnvironmentFor many applications, it may be useful to be able to estimate creep
properties of a material from simpler testing procedures such as tensile tests
than the conventional creep testing procedures. Most alloys used for creep
service conditions are in a hardened condition and thus tertiary creep,
controlled by micro structural degradation, is dominant. The object of the
study was to investigate a reasonably simple method for estimating the creep
behavior of a low alloy 1% Cr, 0.25 % Mo steel from tensile yield data. The
study involved performing of series of investigations, including age hardening,
tensile and creep tests.
Microstructural degradation was monitored from specimens held in a furnace
for different times and temperatures, which were then tested in tension at
room temperatures. Tensile tests were carried out at different temperatures
and strain rates and the data used to determine material parameters for use
in kinetic equations describing deformation. For comparison, creep curves
were obtained from both creep tests and tensile tests results. Tests on
furnace aged specimens were used to quantify softening due to material
degradation and formulate a structure evolution and kinetic expressions used
to determine creep curves.
The modified equation by Dorn was used to determine the material parameters
and to predict flow characteristics. Two sets of mechanisms were observed. At
low temperature and high stress (above 550MPa) dislocation by glide
mechanism was investigated. At higher temperatures and low stress (below
550MPa), some form of power law creep was observed. Glide mechanism was
investigated and material parameters σ ) , n and activation volume v, were
calculated. The calculated value of σ ) was assumed for both plastic deformation
and the softening kinetics.
A reasonably good estimate of the creep behavior of the low alloy steel used
in this investigation in which tertiary creep dominates can be calculated from
tensile yield stress values. Furthermore, the creep rate and recovery have
similar stress dependences, with the stress and temperature dependence similar to that predicted by recovery theory. The value of activation energy
observed for creep for this alloy is in line with the processes which could be
related to self diffusion.
In order to justify the significance of this study, four existing empirical models
are discussed, highlighting their merits and demerits with respect to the models
used in this study. These are θ-Projection, Damage Mechanics, Estrin-Mecking
and the Internal Stress Methods. Generally, in this class of alloys, recovery
process occurs under an effective stress (i.e. an applied stress less the internal
stress). Thus the possibility of using tensile data obtained in this study in the
internals stress model was explored. The model could replicate the one used in
this study if the change in internal stress value o σ is assumed to be negligible.
This could be assumed to be true for tensile data at high stresses and low
temperature especially during secondary creep rate when the internal stress
approximates to the applied stress and at short test durations
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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