1,720,954 research outputs found
Piezoelectric MEMS cantilever power generators for vibration energy harvesting
No full text本論文主要在提出壓電懸臂樑式微型能量擷取元件之開發。此微型能量擷取元件能從環境中擷取機械振動能，並將之轉換成電能。此一能量轉換的作用主要是透過鐵電材料鈦鋯酸鉛(PZT)來達成。藉由壓電之d31及d33能量轉換的模式，可分別開發出輸出特性不同的微型能量擷取元件。此外，本論文也開發出雙層壓電材料之懸臂樑式微型能量擷取元件，並可利用雙層材料之串聯及並聯模式提供不同的輸出特性。藉由理論模型的分析，可以分別探討三種懸臂樑式微型能量擷取元件的輸出能量、輸出電壓及最佳阻抗特性。並且推導出設計參數如元件幾何尺寸、壓電材料性質及材料參數對輸出特性的影響。透過微機電製程技術，成功開發出三種微型能量擷取元件，包含採用上下電極輸出的d31模式元件、採用指叉電極輸出的d33模式元件與雙層壓電的d31模式元件。為了提高輸出電壓，壓電層主要是利用沉積效率高且低溫製程的氣膠沉積法進行製作。實驗結果證實了我們開發的微機電元件有能力產生微瓦等級的能量，且輸出電壓高於全橋整流電路的最低要求。Over the years, there has been a growing interest in the field of power harvesting technologies for low-power electronic devices, such as wireless sensor networks and biomedical sensor applications. Of all possible energy sources, the mechanical vibrations have been considered a potential choice for power harvesting in a wide variety of applications. This dissertation presents the development of cantilever-based piezoelectric MEMS power generators which have the ability to scavenge mechanical energy of ambient vibrations and transform it into useful electrical power that can be used in energy storage applications. The piezoelectric MEMS generators utilize the lead zirconate titanate (Pb(Zr,Ti)O3, PZT) material for transforming mechanical strain energy into electrical charge by using the d31 and d33 modes of PZT. A MEMS piezoelectric bimorph generator is also developed with serial and parallel connections. A theoretical model is presented to investigate the relations between the output characteristics and the design parameters of the piezoelectric MEMS generators. To improve the piezoelectric MEMS generator fabrication process, a self-made PZT deposition chamber which could deposit PZT thin film up to tens micron in minutes was used to deposit the piezoelectric layer on the beam structure of the piezoelectric MEMS generator. Experimental results confirm that our devices have the ability to generate power in the micro-watt range and the output voltage is higher than the minimum requirement for diode band-gaps in the rectifier circuit
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
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