1,721,173 research outputs found
Semiclassical Cross-Regime Rarefied Gas Flow Simulations Using Smooth Transition Zone
No full text在本研究當中求解半古典波茲曼BGK模型方程式(Semiclassical Boltzmann Bhatnagar-Gross-Krook)，使用Maxwell-Boltzmann, Fermi-Dirac和 Bose-Einstein三種不同統計，模擬量子氣體流場。並且使用將微觀尺度方程式與巨觀尺度方程式耦合的模型，該方法是藉由定義截斷函數，建立平滑轉換區於兩不同尺度的方程式之間。在平滑轉換區內，將速度分布函數由截斷函數分解成一個耦合方程組，其中一方程式投影至尤拉極限。平滑緩衝區內的解答，即為該耦合方程組的兩條方程式所求解出的分布函數相加而得。在本文當中考慮線性、餘弦和雙曲函數三種不同的截斷函數，測試不同截斷函數轉換的效果。藉由定義截斷函數，可以簡易的決定於哪一流域求解巨觀方程式、微觀方程式或者將兩者耦合的平滑轉換區。與過往的多尺度耦合方法相比，無須考慮兩尺度方程式之間交界面的邊界條件。在數值方法的部分，本文使用離散座標法，將速度空間從速度分布函數之中獨立出來，使得原半古典波茲曼BGK模型方程式於相空間成為數組具有源項的雙曲線型守恆律方程式。在物理空間部分，使用全變量消逝法和加權型基本不振盪法兩種高解析算則計算。本文中模擬數種量子氣體測試平滑緩轉換區之效果，包含一維震波管問題、二維非穩態震波繞射方柱及穩態流場流過圓柱之流場問題。各算例測試中平滑緩衝區表現良好，可做為多尺度問題耦合法使用。This study solves Semiclassical Boltzmann-BGK equation (also called Uehling – Uhlenbeck Boltzmann-Bhatnagar-Gross-Krook equation) with Maxwell-Boltzmann, Fermi-Dirac and Bose-Einstein statistics which allows us to simulate quantum gas flow problem. In this work, we also implement a buffering zone model which provides a smooth transition between a kinetic and a hydrodynamic domain. The idea is to use buffer zone splitting the velocity distribution function into two coupled equations by cut-off function. The solution will be recovered as the sum of the two coupled equations. We can easily determine to solve kinetic, hydrodynamic or coupled equations via cut function. Three types of cut-function, linear, cosine and hypertangent, are considered in this article. The idea of buffer zone can avoid issue of interface boundary condition between macroscopic and microscopic equation. For numerical parts, we use discrete ordinate method to remove the velocity space dependency of the velocity distribution function which renders Boltzmann equation in phase space to a set of hyperbolic conservation laws with source terms in physical space. High resolution schemes, Total Variation Diminishing (TVD) and Weighted Essentially Non-Oscillatory (WENO), are applied to physical space. Several semiclassical gas flow problems including 1-D shock tube problem, 2-D unsteady shock wave impinging upon a square cylinder and steady flow over a cylinder have been simulated to test the buffer zone treatment. Buffer zone performed well in each test problem. It can be implemented in Multi-scale coupling method successfully.誌謝 i
中文摘要 ii
ABSTRACT iii
目錄 iv
符號表 vii
圖目錄 ix
第一章 緒論 1
1.1 引言 1
1.1 文獻回顧 2
1.2 研究目的與動機 3
1.3 本文架構 4
第二章 波茲曼方程式 5
2.1 稀薄氣體動力學 5
2.2 速度分布函數與巨觀量 7
2.3 波茲曼方程式 9
2.4 BGK模型 12
2.5 連續體模型 13
2.6 固體壁面邊界條件 15
第三章 半古典波茲曼方程式 17
3.1 理想量子氣體 17
3.2 半古典波茲曼方程式 19
3.3 半古典粒子運動模型 20
第四章 數值方法 24
4.1 離散座標法 24
4.2 離散座標法之應用 26
4.3 高解析算則 27
4.3.1 全變量消逝算則 28
4.3.2 加權型基本不振盪算則 29
4.4 時間與空間離散 32
4.4.1 全變量消逝法算則之應用 32
4.4.2 加權型基本不振盪算則之應用 33
4.5 廣義坐標系 35
4.6 無因次化 37
第五章 平滑轉換區 39
5.1 波茲曼BGK模型與波茲曼BGK模型方程式耦合 39
5.2 波茲曼BGK模型與尤拉方程式耦合 42
第六章 數值模擬結果與討論 46
6.1 一維量子氣體問題 46
6.2 二維量子氣體問題 47
6.2.1 方柱非穩態流場算例 47
6.2.2 圓柱穩態流場算例 50
第七章 結論與未來展望 85
7.1 結論 85
7.2 展望 86
參考文獻 8
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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