1,722,047 research outputs found
An analytical proof of a certain geometric inequality conjecture of Shan-He Wu
No full textAbstractIn this short note, the authors give a proof of a certain geometric inequality conjecture of Shan-He Wu by making use of some analytical techniques (see Srivastava et al. (2011) [5] and Wu et al. (2010) [6]). Finally, three closely-related geometric inequality problems are posed as open problems
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
Application of the immersed boundary method and arbitrary Lagrangian-Eulerian scheme to simulate local scour in turbulent flow
No full text本研究使用大渦流模式結合沉浸邊界法與移動網格法，模擬流體經過一結構物對底部泥沙所造成沖刷堆積的影響，大渦流模式(Large eddy simulation)為三維的水動力模式，較能捕捉到在高雷諾數下的紊流現象，在高雷諾數的流場中特別重要。結構物表面的複雜邊界主要使用沉浸邊界法(Immersed boundary method)來處理，與傳統的貼體法(body-fitting)相比，沉浸邊界法假想力的形式寫進統御方程式使其滿足邊界條件，在卡氏座標即可很有效率的處理複雜幾何或是移動網格的問題，另外再底床網格的部分則使用移動網格法(Arbitrary Lagrangian-Eulerian scheme) 計算網格座標速度使其滿足泥沙傳輸，並且模擬紊流邊界層中的底床形貌變化。
本研究一開始使用沉浸邊界法模擬流體流經一圓柱，改變雷諾數由潛變流模擬至紊流，觀察其尾流的變化，確認邊界與流場符合現實情況後，我們再依照Roulund, et al.(2005)所做的實驗配置，設定邊界條件進行模擬，並且分別討論圓柱前緣沖刷與圓柱下游沙漣(sand ripples)的形成過程，以及紊流動能在沖刷過程中所扮演的腳色，結果發現沖刷最強的區域通常都受到一個持續穩定的上升流場給帶動，如前緣的馬蹄形渦流(horseshoe vortex)。一開始前緣掏刷出來的泥沙會在圓柱後方低壓區域產生堆積，堆積丘的下游處容易產生分離流動使得沙漣更加明顯。而紊流動能大的區域通常為流場交界處，該區域由於其動能消散(disspation rate)十分強，故會使部分懸浮泥沙失去動能而在此沉積。In this study, we apply the large eddy simulation (LES) code that combines the immersed boundary method (IBM) and the arbitrary Lagrangian-Eulerian method (ALE) to simulate the evolution of the erodible bed around a structure. This code is a three dimensional computational fluid dynamics simulator, which is capable of resolving the detailed turbulent flow field. This is particularly important in the high Reynolds number flow. We employ the IBM to model the surface of the structure. Compared to traditional body-fitting methods, IBM applies the body force to satisfy the desired boundary condition. It can efficiently handle the complex geometry and moving grids in Cartesian coordinate system. In addition, we apply the ALE method in our grid. It can calculate the grid velocity to guarantee conservation of sediment mass and simulate bed form dynamics in a turbulent boundary layer.
We simulate flow over a cylinder as a test case for IBM. Cases ranging from the regimes of creeping flow to turbulent flow are investigated. The present numerical model is then validated against the experimental results by Roulund et al.(2005), who investigated erosion around a cylinder in a laboratory setting. We discuss erosion in front of the cylinder, the development of sand ripples behind the cylinder, and turbulence kinetic energy (TKE). The numerical results show that the most dramatic erosion region is affected by the steady upflow associated with the horseshoe vortex. Moreover, we observe that sediments in front of the edge pile up in the lower pressure area. Flow separation easily occurs behind the ripples, leading to the growth of the ripple amplitude. We found that high TKE occurs at regions of flow convergence, which is usually associated with strong dissipation, leading to the deposition of suspended sediments.致謝 i
中文摘要 ii
ABSTRACT iii
圖目錄 vi
表目錄 ix
Chapter 1 緒論 1
1.1 前言 1
1.2 研究動機 2
1.3 文獻回顧 3
1.3.1 沉浸邊界法 3
1.3.2 底床沖刷 4
Chapter 2 理論背景與方法 7
2.1 大渦流模式 8
2.1.1 統御方程式 9
2.1.2 濾波統御方程式 10
2.1.3 曲線座標格式 12
2.1.4 流體離散化計算流程 13
2.2 移動網格與泥沙傳輸方程式 15
2.2.1 密度分層 15
2.2.2 泥沙傳輸方程式 16
2.2.3 移動網格法 17
2.2.4 掏刷方程式 18
2.2.5 底床高度方程式 19
Chapter 3 沉浸邊界法介紹與驗證 22
3.1 沉浸邊界法離散化 22
3.2 流經圓柱之潛變流驗證 27
3.3 流體流經圓柱(不同雷諾數) 31
Chapter 4 底床沖刷模擬與分析 39
4.1 模擬配置 39
4.2 流場分析I (定床) 42
4.2.1 馬蹄形渦流 42
4.2.2 尾跡渦流 45
4.2.3 底床剪應力 46
4.2.4 紊流動能 46
4.3 流場分析II (動床) 48
4.3.1 圓柱前緣分析 48
4.3.2 圓柱後端分析 53
4.4 紊流動能分析 57
4.5 侵蝕深度分析 59
Chapter 5 結論與未來工作 61
5.1 結論 61
5.2 未來工作 63
參考文獻 6
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