1,720,954 research outputs found
Analyzing the heat transfer properties of a phase change material, while scraping the surface in order to make a statement for the usability of the latent storing system in solar thermal power plants
Get PDFUm regenerative Primärenergieträger als hauptsächliche Energiequellen zu verwenden, ist eine kontinuierliche Strombereitstellung von entscheidender Bedeutung um die derzeitig benötigte Energiemenge bereitzustellen. Die Entwicklung von thermischen Speichern ist zur Erreichung dieses Ziels von hoher Bedeutung. Wärme kann sensibel, latent oder thermochemisch gespei-chert werden. Fluktuationen der bereitgestellten Sonnenenergie können durch den Speicher ausgeglichen werden. Durch den Einsatz von thermischen Speichern kann ein wirtschaftlicher und vor allem versorgungssicherer Betrieb realisiert und diese Energieumwandlungstechnologie in seiner Entwicklung vorangetrieben werden. Latente Wärmespeicherung weist eine hohe Speicherkapazität bei isothermen Bedingungen auf. Zweiphasige Arbeitsmedien, wie sie zum Beispiel in direktverdampfenden solarthermischen Kraftwerken vorkommen, weisen die gleiche isotherme Charakteristik auf. Dadurch qualifiziert sich die latente Wärmespeicherung für den Einsatz in direktverdampfenden solarthermischen Kraftwerken. Um die schlechte Wärmeleitfä-higkeit des Phasenwechselmaterials zu kompensieren, benötigt es in bisher untersuchten Kon-zepten große Wärmeübertragungsflächen. Da dies mit hohen Kosten verbunden ist, ist bisher der kommerzielle Einsatz dadurch verhindert worden. Der am Fraunhofer ISE entwickelte Schne-ckenwärmeübertrager entkoppelt die Wärmeübertragerfläche von der Speicherkapazität, was die Wirtschaftlichkeit erhöht. Bei gleichzeitiger Förderung vollzieht das Phasenwechselmaterial einen Phasenwechsel von flüssig nach fest bzw. umgekehrt. Die beim Kristallisationsvorgang aufwachsende Schicht des Phasenwechselmaterials auf der Wärmeübertragerfläche wird durch die Schneckenwellen kontinuierlich abgeschabt. Ziel der Arbeit ist es die Wärmeübergangskoef-fizienten der Schmelze während des Kristallisationsvorgangs zu bestimmen. Um die Vorgänge im SWÜ nachzubilden, wurde ein Kratzwärmeübertrager entwickelt. In diesem wird der Wärme-übergang untersucht. Geeignete Methoden zur Berechnung der Wärmeübergangskoeffizienten werden auf Grundlage der Vorgänge erarbeitet und vorgestellt. In Laborversuchen wird der Einfluss der aufwachsenden Schicht des Phasenwechselmaterials ermittelt. Die während der Versuchsdurchführung und der anschließenden Auswertung erlangten Ergebnisse werden disku-tiert und vorgestellt.To use regenerative primary energy carriers as pimary energysources, a continuous supply of current is essential to provide the amount of energy needed. The development of thermal stor-age is fundamental for the success of this process. Heat can be stored with low losses in three ways: sensitive, latent or thermochemically. Fluctuations of the power provided by solar energy can be compensated through the storage. Through thermal storage, running a profitable and uninterrupted solar thermal power plant is made possible and the development of this energy transformation technology can be driven forward. Latent heat storage has a high thermal reser-voir capacity when deployed under isothermal conditions. Biphase working fluids, which are for example used in directly vaporizing solar thermal power plants, show the same isothermal char-acteristic. Therefore, latent heat storage qualifies for the usage in directly vaporizing solar ther-mal power plants. In order to deal with the poor thermal conductivity of the phase change material, a large surface for the heat transmission is currently essential. But because this is di-rectly linked to high production costs, the commercial application of the technology has not been possible yet. The screw heat exchanger, developed at Fraunhofer ISE, uncouples the heat transmitting surface from the thermal reservoir capacity. Under continuous conveyance, the phase change material changes its phase from liquid to solid or vice versa. The layer of phase change material building up on the heat transmission surface, in the process of crystallization, is continually being chipped off by the worm shaft. The goal of this thesis is to evaluate the heat transfer coefficient of the smelter during the process of crystallization. The processes occurring during the phase change are therefore simulated in a scraping heat exchanger. Methods for the calculation of the heat transfer coefficient are worked out on the basis of these findings. The effect of the growing layer of phase change material on the heat transmission surface is determined in laboratory experiments. The results gained in the experimental procedure are finally discussed and presented
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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