1,721,294 research outputs found
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
Control Design of a Micro-Positioning Platform using Piezoelectric Actuators
No full text本研究主要在設計壓電致動器的追跡控制器。壓電致動器的非線性現象主要是受磁滯現象所影響，本研究首先利用Preisach model描述磁滯行為，再利用此模型以前饋控制器來補償，最後結合演算法決定PID控制器增益消除建模誤差。此外，本研究亦針對雙軸運動控制下的循跡誤差問題，提出一嶄新的交叉偶合控制器加以補償。實驗驗證方面，在PC-based壓電控制平台架構下，利用前饋控制器與閉迴路結合進化演算法的PID控制器進行單軸定位控制；雙軸運動控制時則再加入交叉偶合控制器來進行循跡誤差補償。The purpose of this study is to design a tracking controller for a piezoelectric actuated platform. First, a Preisach model is constructed to numerically describe the hysteresis behavior of piezoelectric actuators. Next, on the basis of the Preisach model, a feed-forward controller is developed to compensate for the hysteresis nonlinearity. A PID controller is introduced to suppress the tracking error due to the modeling inaccuracy and hence to get precision tracking control. The dual-axes motion control problem for the piezoelectric actuated platform is also investigated. A neural-net based decoupling control scheme is proposed to eliminate the contour error which is typical in dual-axes tracking control problem. The developed approaches are numerically and experimentally verified which demonstrate performance and applicability of the proposed designs under a variety of operating conditions.致謝 i
摘 要 ii
Abstract iii
目錄 iv
圖目錄 vi
表目錄 xiii
表目錄 xiii
第一章 導論 1
第二章 壓電致動器 5
2.1 壓電材料 5
2.2 壓電效應 6
2.3壓電致動器的優缺點 6
2.4 磁滯效應 8
2.4.1 實驗驗證 8
2.4.2 磁滯效應的實驗與觀察 9
2.5 潛變效應 10
第三章 磁滯系統建模 11
3.1 Preisach模型 11
3.2 壓電致動器磁滯建模實驗步驟 15
3.3 實驗結果 16
第四章 追跡控制系統設計 18
4.1 單軸控制 18
4.1.1前饋追跡控制器 18
4.1.2 迴授PID結合進化演算法的控制器 19
4.1.3實驗步驟與結果 23
4.2 交叉耦合控制在雙軸系統 25
4.2.1 描述雙軸系統 25
4.2.2 輪廓誤差 26
4.2.3 交叉耦合控制器 28
4.2.4實驗步驟與結果 30
第五章 結論 33
參考文獻 3
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
Design of Hybrid Guidance Law for Interception of Ballistic Targets
No full text第一部份： 最佳導引律之設計
本研究之主要目的在探討有效反制高速進襲目標之地對空飛彈中途導引律。 探討此一論題的主要關鍵在於攔截過程無可避免的物理限制，亦即，攔截飛彈之速度遠低於進襲目標，因而傳統反戰機之類的導引律無法應用於此。 根據文獻上的初步研究結果，反制速度遠高於攔截器之目標時，攔截器的朝向角在鎖定目標之際應接近於180度，方能獲得較低的誤失距離。為達此目的，本研究以最佳的中途導引律配合以比例導引為主的終端導引律並採用前饋式的纇神經網路以修正導引誤差，並拓展防禦空間。此架構可在飛彈進入終端階段時，提供較佳的歸向條件，使得攔截器彈道與目標間的朝向角接近180度，因而有效反制如彈道飛彈之高速進襲目標。其中最佳中途導引律的解析解亦嘗試導出，同時在之後的數值模擬中也可得到導引律優越的強健性。
第二部份： 適應性Spline飛彈導引律設計
隨著飛彈射程的增長以及彈道飛彈的多重進襲角度，除了使飛彈能準確的擊中目標之外，如何節省能量並將飛彈導引到適當位置來達成攔截的目標也是設計導引律的重要課題。本研究也利用傳統Spline導引律的架構，提出一種適應性S-4導引律。研究的方法在於利用spline曲線的多邊界條件配合適應性模糊類神經網路的參數調變來設計彈道，以提昇飛彈攔截性能和強健性。Part 1 : Optimal Guidance Design
An optimal midcourse guidance law based on the optimal trajectory shaping is analytically developed to create a near head-on interception condition so that an aerodynamically controlled missile is capable of intercepting a ballistic target. To further improve the engagement possibility, a multilayer feedforward neural network is incorporated with the proportional navigation guidance at the terminal phase to enhance the missile's agility and correct the guidance command in response to changes in the aerodynamics. The whole defensible volume in three-dimensional space is characterized and the performance robustness is verified.
Part 2 : Adaptive Spline Guidance Design
With the increasing range of missile trajectory, the midcourse guidance is usually designed to save the energy and have to increase terminal speed. The aim of the missile guidance is not only to bring the missile to the intercept point, but also to shape the trajectory to make the flight path into the low drag aerodynamic coefficient altitude. In this research, the missile's flight trajectory is shaped by using the combination of ANFIS with Spline-4 guidance. Based on the feature of adaptively, it is shown that our proposed guidance law offers better performance robustness than the conventional designs.Contents
中文摘要 i
第一部份： 最佳導引律之設計 i
第二部份： 適應性Spline飛彈導引律設計 i
Abstract ii
Part 1 ： Optimal Guidance Design ii
Part 2 ： Adaptive Spline Guidance Design ii
致謝 iii
Contents iv
List of Figures vi
List of Tables ix
List of Tables ix
Chapter 1 Introduction 1
Part 1 1
Part 2 3
Chapter 2 Missile and Target Dynamic Models 5
Chapter 3 Attack Strategy for Engagement 8
3.1 Vertical plane guidance 10
3.2 Horizontal plane guidance 12
Chapter 4 Optimal Midcourse Guidance Law 14
4.1 Vertical plane guidance 14
4.1.1 Midcourse phase: optimal sense-based midcourse guidance 14
4.1.2 Shaping phase: PN shaping guidance 20
4.1.3 Terminal phase: combination of PN shaping and neural net-based terminal guidance 21
4.2 Horizontal plane guidance 26
Chapter 5 Adaptive S-4 Spline Guidance Design 28
5.1 Problem Description 28
5.2 Description of Spline-N Guidance Law 30
5.3 Derivation of S-4 Guidance Law 31
5.4 Adaptive Spline-4 Guidance Law 39
5.5 Adaptive guidance parameters update law 43
Chapter 6 Simulation Results and Analysis 49
Part 1 49
Part 2 51
Chapter 7 Conclusions 53
Part 1 53
Part 2 5
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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