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Research on Tornado-Like Vortices
No full text本研究主要改善由陳正平與郭鴻基兩位教授所合作發展的模擬龍捲渦旋產生儀器；針對儀器所得到的實驗結果，渦旋會呈現柱狀之片流渦旋，但是此渦旋只有上升運動，不會類似實際的龍捲風在中心有下沈氣流的出現，或是出現上層亂流區。本論文針對之前的儀器進行改良，使得此儀器實驗可以產生和大自然的龍捲風更為相似之渦旋。
本論文參考了Ward (1972)和Church et al. (1979)之前做的實驗儀器。在本實驗儀器裡面加入了擋板(baffle)，而且將之前儀器輻合區扇葉改良為可調式的。擋板的目的是為了提供一個下沈氣流的上邊界條件。而可調式的扇葉則方便我們控制內流角，以分析因為不同內流角所產生不同切向風與徑向風的比例，探討渦旋半徑以及渦旋結構之關聯。
實驗中可以發現，在相同的結構比例之下，似龍捲渦旋半徑會隨著內流角θ的增加而增加。而渦旋結構，會因為Swirl ratio(S)的漸增，產生單一渦旋、渦旋崩潰、雙渦旋互繞，甚至有三渦旋互繞的結構出現。我們也整理了Swirl ratio在各個渦旋結構過渡的臨界值，其結果和Church et al. (1979)的實驗類似。
在儀器實驗中，亦觀測到釵h細絲帶在渦旋的周圍，我們以角動量守恆及動能守恆來解釋這些細絲帶之成因。並透過數值實驗，模擬三維渦旋在增強的過程中，渦旋為了保持角動量守恆，而外放出來的渦度帶和細絲帶是有關係的。從數值實驗結果發現在渦旋內縮，渦度外放的同時，渦旋周圍的氣壓擾動和渦度細絲的分佈相符合，而且比較渦旋周圍的氣壓擾動和實際觀測的氣壓擾動，發現結果非常的相似。因此我們認為外放的渦度帶和造成氣壓的擾動是有相關性的。目錄
目錄 …………………………………………………….. i
圖表說明 ………………………………………………. iii
1. 前言 ……………………………………..…..………. 1
1.1 背景與文獻回顧 ………………………….……….. 1
1.2 研究動機 ………………………………………..…. 5
2. 實驗儀器之改良 …………………………………. 7
2.1 可調式內流角 ………....…………………………... 7
2.2 擋板(Baffle) …...…………………………………... 8
3. 實驗結果 …………………………………………… 11
3.1 結構比例 ……………….……………….…………. 11
3.2 Swirl ratio ...……………………………………..…. 13
4. 數值實驗 …..………………………………………. 15
4.1 數值實驗方法 ………….……………….…………. 15
4.2 數值實驗結果 …………………………………..…. 16
5. 討論 ………..………………..……………………... 19
5.1 影響似龍捲渦旋的參數 …………………………... 19
5.2 數值模擬分析似龍捲渦旋的結果 ………………... 24
6. 結論 …………………………………………………. 26
參考文獻 ………………………………….…………… 29
圖表 ……………………………………………….……. 30
附錄 …………………………………………………….. 8
Star-Shaped Molecules Containing Polyalkynyl Groups with Metal Moieties on Benzene and Triphenylene Cores
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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
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