1,720,953 research outputs found
Heat Transfer Enhancement in Sintered Porous Microchannels with Two-Particle Distribution
No full text相變化熱傳應用於微流道具高均溫性與低工質需求等優點，能有效提高其散熱效率；多孔表面結構提供大量成核址和連通孔洞更能提升微流道熱傳性能。本研究於1平方英吋銅表面以樹枝狀銅粉燒結多孔微流道蒸發器，以R-134a為工質，在流量範圍133~417ml/min、飽和壓力800kpa下進行熱傳實驗。探討不同孔徑分布對多孔微流道之熱傳、壓降、壓力不穩定性的影響，並與平板流道進行比較。
實驗結果顯示平板微流道蒸發器的熱傳係數在乾度小於0.4前，屬於核沸騰機制；實驗所得熱傳係數代入Cooper池沸騰經驗式之總平均誤差為8.2%，而乾度於0.4以上，屬強制對流沸騰為主。臨界熱通量隨流量上升而增加，可達127.9W/cm2。而壓降則隨流量與熱通量上升而增加，帶入考慮表面張力與黏度之分離流壓降經驗式總平均誤差約17%。壓降震盪顯示平板微流道具有不穩定性，其震盪幅度在接近起始沸騰時最大，流量效應影響不大。
多孔性結構微流道蒸發器熱傳係數在低熱通量時就達到峰值，隨熱通量與乾度上升而下降，隨質量流率上升而增加，與平板流道乾度於0.4以上趨勢相近。探討不同參數的實驗發現，孔徑分布直接影響熱傳性能，而具雙孔徑分布結構更能有效提升。最佳多孔微流道熱傳係數較平板微流道提升10倍；臨界熱通量並與平板差異不大；壓降較平板微流道平均增加20%；而最大壓降振幅較平板微流道下降47%，顯示其散熱應用上與流動穩定方面極具潛力。Phase-change heat transfer provides advantages such as good temperature uniformity, less coolant flow rates requirement and high cooling efficiency. Porous media surface possesses a lot of nucleate sites and the connected pores which can enhance heat transfer coefficient. In present study, the flow boiling experiments were conducted with porous microchannels evaporators sintered with copper dendritic powder on 1 square inch copper substrates. Working fluid R-134a was used at volume flow rate from 133~417ml/min and the saturated pressure of 800kpa. The purpose of this research is to investigate heat transfer characteristics, pressure drop, pressure instability, heat transfer enhanced in different pore distributions and to compare with plane microchannels evaporators.
The results of the plane microchannels evaporator showed the heat mechanism was dominated by the nucleation boiling before quality 0.4. The experiment data were substituted into the Cooper’s pool boiling correlation, the mean average error was 8.2%. On the other hand, when the quality was over 0.4, the heat mechanism was dominated by the forced convection boiling. Critical heat flux (CHF) increased with increasing volume flow rate and reached to 127.9W/cm2. The pressure drop increases with increasing heat flux and volume flow rate. The experiment results also substituted into the correlation considered surface tension and viscosity, and the average error was 17%. Pressure drop oscillation suggested the presence of instability inside the plane microchannels. The maximum amplitude of oscillation was found to be near the onset of nucleation and independent of volume flow rate.
The experiment results showed that the heat transfer coefficient of porous microchannels reached the peak value at low quality, than decreased with increasing quality and increased with increasing volume flow rate. The trend is almost the same with plane microchannels when the quality is over 0.4. The investigation of different parameters indicated that pore distribution affects the heat transfer characteristic directly. The heat transfer coefficient can be enhanced with dual- pore distribution structure. The best performance were achieved by the porous microchannels and the heat transfer coefficient enhanced about 10 times larger than the plane microchannels. Pressure drop and the maximum pressure instability amplitude of porous structure channel was 20% higher and 47% lower than plane channel near the onset of nucleation respectively. To conclude the results of the study, the porous microchannels evaporator is highly potential for the industrial cooling applications and flow stability
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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