1,721,002 research outputs found
Reliability testing and heat transfer enhancement of organic phase change materials / Ravi Kumar Sharma
Full text linkThe design and development of a thermal energy storage device require discrete selection of the appropriate phase change material (PCM) and a suitable container to contain them. This study focuses on the selection of PCMs for solar thermal energy storage devices and the improvement in their thermophysical properties. In addition, a new shape of the PCM container is also investigated using computational fluid dynamics.
The accelerated thermal cycle test is an essential requirement to ensure the thermal and chemical stability of selected PCMs to be used in practical applications. Solar energy being an unlimited natural energy source is used in a large number of applications such as solar water/air heating, cooking, drying and other domestic and commercial applications. On the other hand, this energy also has limitations as this is available only in the daytime. Storage of this abundantly available solar energy can be effectively used in the night hours or when there are no sunny days. Four organic PCMs-paraffin wax, palmitic acid, myristic acid, and polyethylene glycol (PEG) 6000, all in the melting temperature range of 50-70 ˚C, have been considered in this study and the changes in their thermal and chemical properties have been measured using the differential scanning calorimetry and the Fourier transform infrared techniques. The results of this research work revealed that the changes in the melting temperature of paraffin wax, palmitic acid, myristic acid, and PEG 6000 were in the range of +0.72 ˚C to +3.27 ˚C, -0.29 ˚C to +1.76 ˚C, -2 ˚C to +1.2 ˚C, and 3.77 to 3.94 ˚C respectively. The variation in the latent heat of fusion was found in the range of -9.8 to 14%, 3.28 to 18%, 0.9 to 10%, and 13 to 25 % for paraffin wax, palmitic acid, myristic acid, and PEG 6000 respectively.
iv
The low thermal conductivity of organic PCMs is a well-known drawback which limits their use in many domestic and industrial applications. A composite of palmitic acid and nano titanium dioxide (TiO2) was prepared and its phase change behavior was investigated. TiO2 nanoparticles of 0.5%, 1.0%, 3.0%, and 5.0% were dispersed into palmitic acid and the thermophysical properties of these nano composites were measured. The composite PCMs were characterized by FESEM, XRD, and FT-IR. The thermal properties, thermal stability and thermal reliability were ensured by DSC, TGA, and thermal cycle testing. FESEM images show the uniform dispersion of nanoparticles in the palmitic acid and FT-IR spectrum indicate that the composite PCM possesses good chemical stability and interaction between PCM and nanoparticles. The results of a thermal conductivity test show that the dispersion of the 5% nanoparticles enhances the thermal conductivity of palmitic acid by 80%.
Finally, a novel trapezoidal cavity is proposed for containing the PCM and a detailed parametric study was carried out using two nano enhanced PCMs, paraffin-Cu and water-Cu based on the computational study. The effect of side wall inclination angle, cold wall temperature, nanofluid’s initial temperature, cavity inclination, Grashof number on the total solidification time of nanofluid was simulated. The total solidification time for different wt% of Cu nanoparticles was also investigated in the trapezoidal cavity. The enthalpy–porosity technique is used to trace the solid–liquid interface. The inclination angle can be used efficiently to control the solidification time. In addition, the average Nusselt number along the hot wall for different angles, nanoparticles volume fractions, and Grashof number are presented graphically. The proposed predictions are very helpful in developing an improved latent heat thermal energy storage for the solar heat collector and for casting and mold design
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
- …
