1,720,953 research outputs found
Development and Characteristic Study of a Small Rotor Eddy Current Damping System
No full text當一導電體受到一時變磁通量時，在導電體中即會產生渦電流，渦電流會產生與時變磁場磁極方向相反的磁場(二次磁場)，磁場的相互作用即產生抵抗磁場變化的力量。藉由導電體的電阻，會將渦電流以熱損耗方式釋出，如此則可以消耗掉意圖改變磁場之振動動能，而達到減振的效果。本論文的研究目的在於設計製作可靠且高性能的轉軸渦電流減振系統，使其能滿足小型轉軸在偏擺時所需要的減振功能。首先彙整參考文獻及探討轉軸渦電流減振的作用原理，並在評估許多設計參數與變異性之後，從而進行轉軸渦電流減振系統的實體設計以及組裝。本論文同時從理論模型以及有限元素模型的分析，了解各個設計參數對於渦電流減振作用的影響。接著對所完成的轉軸渦電流減振系統進行動態特性的測試，以減振力、阻泥比和減振時間常數來評比減振系統之性能表現。在提升減振系統的性能上，提出了雙環形磁石排列方式以及環形Hallbach磁石排列方式，可以提升減振效能使阻尼比2~4倍，另外對也提出渦電流限轉磁石配置方式，可以改善高轉速不穩定現象。When a conductive material is subjected to a time-varying magnetic flux, eddy-currents are generated in the conductor. These eddy-currents circulate inside the conductor generating a magnetic field of opposite polarity as the applied magnetic field. The interaction of the two magnetic fields causes a force that resists the change in magnetic flux. Due to the internal resistance of the conductive material, the eddy-currents will be dissipated into heat, consuming the kinetic energy of the vibrating element, the conductor or the magnet, which causes the time-varying magnetic flux, and thus producing a damping effect. The aim of this thesis is to develop a reliable and high performance of rotor eddy-current damping system which satisfies the damping capability needed to absorb the lateral vibration of small rotating machinery. This thesis will first investigate and analyze numerous literature surveys on working principle of rotor eddy-current damping. The thesis then advances to estimation of numerous design factors and variations of fabrication process. Theory model analysis as well as finite element analysis are being used to understand the influence of different design variables on the damping system. Dynamic characteristic testing is applied to evaluate the damping system performance by comparing damping force, damping ratio and damping time constant on various designs. Finally, this thesis proposed a novel double ring magnet arrangement and a novel Hallbach ring magnet arrangement, which improve the damping system performance by increasing the damping ratio by 2~4 times. Eddy-current rotation restriction magnet arrangement is also being introduced which has been proven to greatly improve the instability problems during the high speed operations.誌謝 I
中文摘要 II
英文摘要 III
目錄 IV
表目錄 VII
圖目錄 VIII
符號表 XII
第一章 緒論
1.1 研究背景與動機 1
1.2 文獻回顧 3
1.3 內容簡介 11
第二章 小型轉軸渦電流減振系統之工作原理與理論
2.1 渦電流介紹 12
2.2 渦電流的應用 18
2.2.1 渦電流用於能量或力量的產生與轉換 18
2.2.2 渦電流量測原理之運用 21
2.3 渦電流減振之工作原理 22
第三章 小型轉軸渦電流減振系統之設計開發
3.1 概念設計 27
3.2 實體設計 35
第四章 理論模型建構與模擬分析
4.1 理論模型建構 43
4.2 有限元素模擬分析 51
4.3 系統運動方程式 55
第五章 小型轉軸渦電流減振系統之測試與特性分析
5.1 實驗架構 59
5.2 系統測試 68
5.3 影響參數探討 76
5.3.1 導電圓盤材料的影響 76
5.3.2 導電圓盤厚度的影響 77
5.3.3 導電圓盤直徑的影響 79
5.3.4 空氣間隙的影響 81
5.3.5 相對移動速度的影響 81
5.3.6 磁石排列型式的影響 82
5.3.7 導電圓盤形狀的影響 85
5.3.8 導電圓盤旋轉速度的影響 87
第六章 結論與未來展望 93
參考文獻 95
附錄A 伺服馬達規格與特性 98
附錄B 編碼器規格與特性 99
附錄C 伺服馬達控制器規格與特性 100
附錄D 雷射位移量測器規格與特性 101
附錄E 測力規規格與特性 102
附錄F 資料擷取卡規格與特性 103
附錄G 電磁鐵規格與特性 105
附錄H Matlab程式：實驗運動曲線與指數衰減 106
附錄I Matlab程式：理論運動曲線 108
附錄J 渦電流減振系統架構設計圖 11
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
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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