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FUNDAMENTAL TECHNOLOGIES FOR THE OPTO MECHANICAL GYROSCOPE
No full text138 pagesOpto-mechanics is the convergence of optics and mechanics towards the understanding of novel physical phenomenon and the achievement of cutting edge applications. From the effects of radiation pressure on the study of gravitational waves in a LIGO to the study of the quantum mechanical ground state of a simple harmonic oscillator, opto-mechanics spans a very wide range of the physical world. Optical systems with their capability of high sensitivity have been evaluated for applications as sensors like heart rate monitors, gas sensors and LIDARs. There has also been a growing demand for more robust, sensitive, low cost and easy to integrate gyroscopes for applications ranging from defense to autonomous driving. While there are existing technologies for high performance gyroscopes like the ring laser gyroscope and the machined hemispherical resonator gyroscope, these can be large, expensive and unwieldy rendering them unsuitable for a wide variety of applications. MEMS based gyroscopes are low-cost, come in smaller packages and are easy to integrate into systems but they might not have the high performance desired in these new demanding applications. Opto-mechanics has the potential to bridge the gap by combining MEMS and optics to leverage the high sensitivity of optics with the low cost and ease of integration of MEMS devices. The work presented in this thesis showcases some of the fundamental technologies needed for an opto-mechanical gyroscope (OMG). First is the scale hemispherical opto-mechanical resonator that is meant to incorporate the highly desirable mechanical properties of the cm scale hemispherical resonator gyroscope. These silicon dioxide resonators were fabricated in a MEMS centric process flow. The mechanical modes were optically sensed with a tapered optical fiber coupled to a toroidal optical cavity fabricated on the lip of the hemispherical resonator. Next is the development of silicon opto-mechanical wineglass mode resonators with on-chip waveguides. The silicon-on-insulator (SOI) platform employed here allows for better integration of the electro-static actuation and opto-mechanical sensing of the wineglass modes. The two orthogonal n=2 wineglass modes can be used for gyroscopy. Here, I first present the path towards closing the loop on the gyroscope drive wineglass mode. The differential electro-static actuation scheme achieved an 18db relative suppression of the undesired radial mode relative to the wineglass mode. The differential opto-mechanical sensing achieved a 5.4db enhancement of the drive wineglass mode detection and a further 11dB attenuation of radial mode. The suppression of the spurious modes relative to the desired wineglass mode allows a path for closing the oscillator loop on the wineglass mode without the need for additional filters. Next, I present the electro-static actuation of the drive wineglass mode and the opto-mechanical sensing of the orthogonal sense wineglass mode around 22MHz. The resonator was specially designed to achieve a controlled frequency mismatch between these two wineglass modes of only 120KHz and the design allows for tuning this further as needed. Measurements in vacuum showed an optical Q of 61,000 for the optical ring cavity mode and a mechanical Q of 11,500 for the drive wineglass mode and 7,670 for the sense wineglass mode. Last is the work with Lithium Niobate (LN) resonators. LN is of interest for its piezoelectric properties where the large piezoelectric coupling coefficient () allows for efficient electrical actuation of its mechanical modes. There is a potential for leveraging the high efficiency mechanical mode actuation to actuate the drive mode of a gyroscope device. Typically these resonators are actuated with gold but gold has been found to be mechanically lossy. Aluminum was chosen to be the replacement of gold in this work for its lower mechanical losses compared to gold. However, aluminum is very reactive with hydrofluoric acid (HF) which is used as part of the fabrication process of these devices. This necessitated an exploration of passivation methods to protect the aluminum electrodes from HF. Among the various films that I evaluated, a protective film called ProTEK PSB was found to be the most promising in resisting HF while protecting the aluminum electrodes. ProTEK PSB also had a process for its removal after the HF processing. In summary, this work presents some of the fundamental technologies such as a scale high mechanical performance device, a chip scale platform for selective transduction of the wineglass modes and a path towards high efficiency actuation of mechanical modes, all of which could contribute towards building an opto-mechanical gyroscope
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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