1,720,964 research outputs found
Assessment of helical-cruciform fuel rods for high power density
No full textIn order to significantly increase the power density of Light Water Reactors (LWRs), the
helical-cruciform (HC) fuel rod assembly has been proposed as an alternative to traditional
fuel geometry. The HC assembly is a self-supporting nuclear fuel configuration consisting
of 4-finned, axially-twisted fuel rods closely packed against one another in a square array.
Within the LWR core, HC fuel would in theory possess several inherent advantages over
traditional fuel, potentially allowing for operation at a higher power density. Chief among
these advantages are a larger surface-to-volume ratio, a shorter radial heat conduction path,
and improved mixing characteristics.
In previous work, computational models of the HC fuel assembly have been of limited
accuracy due to the absence suitable correlations. To address needs within these subchannel
analysis models, experimental measurements of rod bundle coolant mixing have been
conducted with 4x4 arrays of HC test rods. The tests used the technique of a hot water
tracer injection (at 95°C) into a bulk flow of cold water (at 25°C). Downstream temperature
measurements were used to judge the rate of lateral cross-flow within the HC rod bundle.
These tests were conducted at atmospheric pressure, and encompassed a range of mass
fluxes from 1000 kg/m2s to 3500 kg/m2s, HC rod twist pitches of 200cm, 100cm, and
50cm, and different hot water injection velocities and mixing lengths.
Data from over 300 tests was analyzed, yielding a best fit correlation for use with any twist
pitch, rod length, or coolant flow rate. Compared to the bare rod bundle, this correlation
implies an enhancement in the intensity of turbulent interchange of 40% brought about by
the HC geometry, and a 1.6% forced diversion of axial flow per subchannel, per quarterturn
along the rod length. These parameters fit all data points considered within a standard
deviation of 24%. Stochastic error was limited to ±16% by the use of precise temperature
sensors.
By applying this empirical mixing model to the subchannel representation of a BWR core
featuring the HC rod design, a need to increase the flow area of the edge subchannels was
demonstrated. This prompted a slight re-design of the HC fuel rod cross-section in order to
make room for small spacer protrusions at the duct wall, to increase flow to peripheral
subchannels. The modification was accomplished by reducing fin length, but increasing the
inner diameter to maintain the reference fuel volume. The water rod region was also
adjusted to maintain the reference assembly hydrogen to uranium atom ratio. With this
modification, the model predicted a 24% allowable power uprate for the 200cm twist pitch
HC core. Inlet and exit enthalpies were maintained from the reference cylindrical-rod core.
When applied to a PWR core of HC rods, also with a fixed power to flow ratio, this
empirical mixing model predicted an allowable power uprate of 47%, using traditional CHF
correlations for cylindrical fuel. In subcooled conditions, CHF is known to be more
sensitive to peaked areas of non-uniform heat-flux than in saturated two-phase flow
conditions. Therefore power density gains will likely be dependent on the degree to which
the rod twist would disrupt of nascent pockets of vapor; this effect should be further
investigated experimentally.
In order to further ascertain the potential gain in power density for the new design, an
experiment must be carried out to obtain CHF data for the HC rod bundle. Two facilities
with this aim were designed in great detail for BWR conditions: the first would operate
using high pressure water at 7MPa, and the alternate would use a relatively low pressure
refrigerant at equivalent conditions. The appropriate scaling laws were applied, which
resulted in the choice of R134a as the simulant fluid. The R134a facility was found to be
possible to construct at a greatly reduced cost.Tokyo Electric Power Corporatio
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
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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