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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

High-Modulation-Speed LEDs Based on III-Nitride

January 2016 (has links)
abstract: III-nitride InGaN light-emitting diodes (LEDs) enable wide range of applications in solid-state lighting, full-color displays, and high-speed visible-light communication. Conventional InGaN quantum well LEDs grown on polar c-plane substrate suffer from quantum confined Stark effect due to the large internal polarization-related fields, leading to a reduced radiative recombination rate and device efficiency, which limits the performance of InGaN LEDs in high-speed communication applications. To circumvent these negative effects, non-trivial-cavity designs such as flip-chip LEDs, metallic grating coated LEDs are proposed. This oral defense will show the works on the high-modulation-speed LEDs from basic ideas to applications. Fundamental principles such as rate equations for LEDs/laser diodes (LDs), plasmonic effects, Purcell effects will be briefly introduced. For applications, the modal properties of flip-chip LEDs are solved by implementing finite difference method in order to study the modulation response. The emission properties of highly polarized InGaN LEDs coated by metallic gratings are also investigated by finite difference time domain method. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2016
12

Using Baroque Vocal Music to Introduce Horn Students to the Musical Concepts of Expression, Articulation, Phrasing, and Tempo

Winter, Angela K. 05 1900 (has links)
Baroque music is an area largely neglected in the music education of young horn students and wind players in general. Baroque horn repertoire is very demanding primarily due to the range. Baroque composers wrote for horn using the uppermost register of the instrument. In this range the partials are closer together, allowing for more melodic writing. This music requires an advanced level of technique, endurance, and ability. Often this repertoire is not suitable for students until they are well into their collegiate years of study. Frequently this music is performed on descant horns. Since only a small number of middle school and high school horn students continue to play after they leave their school band programs, they many never get first hand experience performing Baroque music. Vocal students are often introduced to Baroque arias early in their training. Purcell’s songs and arias are an excellent example of the literature that young voice students use. These arias and songs can be the perfect portal to Baroque music for horn students as well. Here I have created an edition of Henry Purcell’s songs and arias for young horn students. Each aria used the text as a guide for the “affect” and its impact on tone, articulation, and phrasing. The bass line is also used as a guide for determining tempo and style. Each piece is transcribed as a solo with piano accompaniment and as a duet. The goal of this edition is to use Baroque vocal music to introduce horn students to the musical concepts of expression, articulation, phrasing, and tempo.
13

Magnetic resonance with quantum microwaves / Résonance magnétique avec des champs micro-ondes quantiques

Bienfait, Audrey 14 October 2016 (has links)
Dans une expérience classique de résonance paramagnétique électronique (RPE), le couplage entre les spins et leur environnement électromagnétique est faible, limitant considérablement la sensibilité de la mesure. Grâce à l’utilisation combinée d'un amplificateur paramétrique Josephson et de micro-résonateurs supraconductuers de hauts facteurs de qualité refroidis à quelques millikelvins, ce travail rapporte la conception et la mise en œuvre d’un spectromètre RPE dont la sensibilité de détection est limitée par les fluctuations quantiques du champ électromagnétique au lieu d’un bruit d’origine thermique ou technique. Des mesures de RPE pulsée sur un ensemble de doneurs Bismuth dans le silicium permettent de démontrer une sensibilité de 1700 spins détectés par écho de Hahn avec un signal-sur-bruit unitaire. La sensibilité est encore améliorée en générant un état de vide comprimé dans le guide d'onde de détection, ce qui réduit les fluctuations quantiques au-delà de la limite quantique. Les hauts facteurs de qualité et le petit volume de mode du résonateur supraconducteur développés pour une sensibilité accrue accroit également le couplage spin-résonateur jusqu'au point où les fluctuations quantiques ont un effet dramatique sur la dynamique des spins. En effet, l’émission spontanée de photons dans le résonateur micro-onde est considérablement renforcée par l'effet Purcell, ce qui en fait le mécanisme de relaxation de spin dominant. Le taux de relaxation est augmenté de trois ordres de grandeur lorsque les spins sont accordés à résonance, démontrant que la relaxation de spin peut-être contrôlée sur demande. Nos résultats fournissent une méthode nouvelle et universelle pour initialiser des systèmes de spin dans leur état fondamental, avec des applications en résonance magnétique et en information quantique. / In usual electron-spin resonance (ESR) experiments, the coupling between spins and their electromagnetic environment is quite weak, severely limiting the sensitivity of the measurements. Using a Josephson parametric microwave amplifier combined with high-quality factor superconducting micro-resonators cooled at millikelvin temperatures, this work reports the design and implementation of an ESR setup where the detection sensitivity is limited by quantum fluctuations of the electromagnetic field instead of thermal or technical noise. Pulsed ESR measurements on an ensemble of Bismuth donors in Silicon spins demonstrate a sensitivity of 1700 spins within a single Hahn echo with unit signal-to-noise (SNR) ratio. The sensitivity of the setup is improved one step further by generating squeezed vacuum in the detection waveguide, reducing the amount of noise beyond the quantum limit. The high-quality factors and small mode volume superconducting microwave ESR resonator developed for enhanced sensitivity also enhances the spin-resonator coupling up to the point where quantum fluctuations have a dramatic effect on the spin dynamics. As a consequence, the spin spontaneous emission of microwave photons in the resonator is dramatically enhanced by the Purcell effect, making it the dominant spin relaxation mechanism. The relaxation rate is increased by three orders of magnitude when the spins are tuned to resonance, showing that spin relaxation can be engineered and controlled on-demand. Our results provide a novel and general way to initialize spin systems into their ground state, with applications in magnetic resonance and quantum information processing.
14

The Vocal Solos from the Incidental Dramatic Music of Henry Purcell

Stone, Edgar Norman 08 1900 (has links)
In this study, every effort has been made to cover the principal factors in the solos from the incidental music which are peculiar only to this part of Purcell's work. The melody and text have been of primary concern. The effects of the social and economic background of the times and the actual dramatic setting of the songs are given careful attention. It is not the purpose of this work to study the harmonic style of Purcell. This is admittedly a most intriguing and attractive subject. However, as the principal accompaniment is the continuo and the implied harmonies of his figured bass are not always clear the harmonic style will not be treated as an element of the solos. It is fully worthy of individual treatment which would be free to draw upon the vast instrumental examples of his work in a comprehensive study of his style. A complete survey of the songs is included in Appendix D for reference and for the information of the reader. It is hoped that the reader will be encouraged to pursue a closer study of these songs, and to consider their possible use today.
15

Geochemical study of the Mesoproterozoic Belt-Purcell Supergroup, western North America : implications for provenance, weathering and diagenesis

Gonzalez-Alvarez, Ignacio Jose 04 January 2006
Provenance in the lower Belt-Purcell Supergroup is constrained based on geochemical systematics and chemical monazite ages of argillites and sandstones. Rare earth element (REE), Cr-Ni, and Th/Sc-Sc systematics is equivalent for both facies and consistent with a dominantly post-Archean source area. Detrital monazite chemical ages restrict major provenance for the Appekunny and Grinnell sandstones and argillites to Paleoproterozoic terranes at ~1800-1600 Ma, minor contributions at ~1600-1500 Ma, and marginal contributions from Archean terranes at ~2600, likely in Laurentia. Similar detrital age spectra for monazites of argillites and sandstones of the Appekunny Formation are consistent with a common provenance for the two facies.</p> <p>The Belt-Purcell sequence records three major diagenetic stages displayed in argillites and sandstones: (1) K-addition and rare earth element post-Archean upper continental crust (PA-UCC)-like pattern; (2) a stage characterized by heavy REE enrichment relative to light REE and HFSE fractionation, and U and Ce mobility; and (3) local dolomitization with REE and high field strenght elements (HFSE) mobility. REE and HFSE mobility are interpreted as the result of oxidized alkaline brines developed by dissolution of evaporites. Monazites from the Appekunny and Grinnell formations differ compositionally and texturally in two groups. Rounded or inclusions with ages >~1400 Ma, interpreted as detrital, have higher Th2O, Y2O3 and lower LREE/HREE contents than euhedral individual monazite grains with chemical ages <~1400 Ma that posses opposed compositional characteristics, and viewed as diagenetic. Monazites that span <~1400 to 300 Ma could be the result of basinal brine activity during stages (2) and (3). </p> <p>Chemical index of alteration (CIA) for argillites and sandstones, corrected for a diagenetic K-addition average 73 and 66 respectively. These results, coupled with correlation of CIA with Eu/Eu*, low K/Cs ratios, and low Sr, Ca, and Na relative to PA-UCC, could be interpreted as the result of an moderate weathered provenance in a hot, wet climate being drained by a large-scale river system. Presence of minor pristine feldspars lowers the CIA values, and may signify minor contributions from proximal source with short-river transport under the arid to semi-arid climate in the depositional setting. Moderate to intense weathering of the larger provenance may be associated with elevated levels of atmospheric CO2 degassed from a mantle plume implicated in the rifting of the supercontinent Columbia at ~1500 Ma.
16

Geochemical study of the Mesoproterozoic Belt-Purcell Supergroup, western North America : implications for provenance, weathering and diagenesis

Gonzalez-Alvarez, Ignacio Jose 04 January 2006 (has links)
Provenance in the lower Belt-Purcell Supergroup is constrained based on geochemical systematics and chemical monazite ages of argillites and sandstones. Rare earth element (REE), Cr-Ni, and Th/Sc-Sc systematics is equivalent for both facies and consistent with a dominantly post-Archean source area. Detrital monazite chemical ages restrict major provenance for the Appekunny and Grinnell sandstones and argillites to Paleoproterozoic terranes at ~1800-1600 Ma, minor contributions at ~1600-1500 Ma, and marginal contributions from Archean terranes at ~2600, likely in Laurentia. Similar detrital age spectra for monazites of argillites and sandstones of the Appekunny Formation are consistent with a common provenance for the two facies.</p> <p>The Belt-Purcell sequence records three major diagenetic stages displayed in argillites and sandstones: (1) K-addition and rare earth element post-Archean upper continental crust (PA-UCC)-like pattern; (2) a stage characterized by heavy REE enrichment relative to light REE and HFSE fractionation, and U and Ce mobility; and (3) local dolomitization with REE and high field strenght elements (HFSE) mobility. REE and HFSE mobility are interpreted as the result of oxidized alkaline brines developed by dissolution of evaporites. Monazites from the Appekunny and Grinnell formations differ compositionally and texturally in two groups. Rounded or inclusions with ages >~1400 Ma, interpreted as detrital, have higher Th2O, Y2O3 and lower LREE/HREE contents than euhedral individual monazite grains with chemical ages <~1400 Ma that posses opposed compositional characteristics, and viewed as diagenetic. Monazites that span <~1400 to 300 Ma could be the result of basinal brine activity during stages (2) and (3). </p> <p>Chemical index of alteration (CIA) for argillites and sandstones, corrected for a diagenetic K-addition average 73 and 66 respectively. These results, coupled with correlation of CIA with Eu/Eu*, low K/Cs ratios, and low Sr, Ca, and Na relative to PA-UCC, could be interpreted as the result of an moderate weathered provenance in a hot, wet climate being drained by a large-scale river system. Presence of minor pristine feldspars lowers the CIA values, and may signify minor contributions from proximal source with short-river transport under the arid to semi-arid climate in the depositional setting. Moderate to intense weathering of the larger provenance may be associated with elevated levels of atmospheric CO2 degassed from a mantle plume implicated in the rifting of the supercontinent Columbia at ~1500 Ma.
17

Music for the Mad : A study of the madness in Purcell's mad songs

Lebedinski, Ester January 2009 (has links)
ABSTRACT "Music for the Mad: A study of the madness in Purcell's mad songs" Ester Lebedinski, Uppsala University, Sweden, Department of Musicology, 2009. Madness was a stock topic in seventeenth-century drama, and music a compulsory feature on the Restoration stage. Henry Purcell's contributions to the latter are abundant, and include the popular combination of madness and music in his mad songs for Thomas Durfey's comedies. This essay aims at exploring the depiction of madness through music, verbal text and dramatic context in Purcell's mad songs for Durfey's plays A Fool's Preferment (1688), The Richmond Heiress (1693) and part I and III of The Comical History of Don Quixote (1694 and 1696 re­spectively). Particular emphasis is laid on text illustration and the songs' placement in the dramatic context. Madness is discussed as a deviation from the accepted norm, as the anormal demarcated from the normal. Conclusively, Purcell's mad songs are characterized by their variousness e.g. rapid changes between keys, styles, moods and subject matters, as opposed to the relative conti­nuousness of songs not depicting madness, and their sometimes exaggerated word paintings. Purcell's music does not independently express madness, but the illustration of madness is linked to the verbal text and the dramatic context, highlighted and completed through Pur­cell's music.
18

An analysis and discussion of conducting performance practices in Steven Stucky's elaboration of Henry Purcell's Funeral music for Queen Mary (1992)

Espinosa, Ricardo Javier, January 2009 (has links)
Thesis (D.M.A.)--UCLA, 2009. / Vita. Description based on print version record. Includes bibliographical references (leaves 35-37).
19

Plasmonic Cavities for Enhanced Spotaneous Emission

Liu, Tsung-li 30 September 2013 (has links)
The modification of spontaneous emission, i.e. the Purcell effect, with optical cavities has been highly studied over the past 20 years as one of the most important goals for cavity quantum electrodynamics (cQED). The recent development of using surface plasmon resonances to concentrate optical field into sub-wavelength scale further extended cQED research of into a new regime. However, although metallic reflectors are used in some of the earliest demonstrations of cQED, the use of metals is not preferable in high Q optical cavities due to the lossy nature of metals. The presence of metals near an optical emitter also strongly alters its radiation dynamics. As a result, the development of plasmonic cavities brings not only new opportunities but also new problems and challenges. In this thesis we describe four different plasmonic cavity designs along with optical simulations and measurements on them to demonstrate: large spontaneous emission enhancement, controlled mode tuning, and control of the plasmonic band-gap and resonances of high-Q plasmonic cavities for coupling to specific emitters. We hope that our work can guide and inspire researchers who are moving from traditional cavity designs to novel plasmonic devices, helping them to establish design concepts, fabrication criteria, and baselines for characterizing these devices. / Engineering and Applied Sciences
20

A Comparison of Origins and Influences in the Music of Vaughn Williams and Britten through Analysis of Their Festival Te Deums

Jensen, Joni January 2005 (has links)
Ralph Vaughan Williams and Benjamin Britten were two of the most prominent and popular composers in England in the first half of the twentieth century; however, their musical styles represent two different schools of thought, pastoralism and modernism. Despite their differences, they had much in common. They attended the same school; were heirs of a movement to promote English music, the English Musical Renaissance; and greatly admired their predecessor Henry Purcell. This document investigates how these two composers formulated diverse compositional styles even though they shared a common musical heritage.The investigation in this document is two-part. First, the investigation depicts the origin and formulation of both composers' styles through a discussion and comparison of their musical backgrounds, teachers, influences, and ideals. This discussion includes information on their personal training and ideas, as well as influential movements, composers, and teachers. The second portion includes analysis and comparison of Vaughan Williams' and Britten's Festival Te Deums. The document includes a discussion of the origin of the Te Deum text and history of musical settings. Specific elements of the Festival Te Deums are discussed, compared, and traced to possible origins of influence in each composer's heritage. This document includes an analysis of Purcell's Te Deum in comparison to the Vaughan Williams and Britten settings as a demonstration of the affects of a common influence on their music.The influences and ideals of each composer clearly manifest themselves in their respective Festival Te Deums. The analysis confirms there are obvious differences in their respective musical ideas; however, the effects of similar influences on their musical styles are not always similar. Although Vaughan Williams and Britten followed the principles of the English Musical Renaissance and emulated Purcell, each composer was so distinct in his musical interpretation that it is difficult to recognize the similar influences in the music itself. In this way, both remained committed to their heritage, but each developed a unique musical voice.

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