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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

Medidas do primeiro coeficiente de Townsend de ionização no isobutano puro submetido a campos elétricos uniformes / Measurements of townsend first ionization coefficient in pure isobutane under uniform electric fields

Anna Raquel Petri 20 March 2013 (has links)
Neste trabalho são apresentados os valores do primeiro coeficiente de Townsend de ionização, α, para o isobutano puro, obtidos com uma câmara de placas paralelas de anodo resistivo no intervalo de campo elétrico reduzido de 140 Td a 230 Td. O método empregado baseia-se em uma nova versão da técnica de Townsend pulsada, onde a ionização primária é produzida pela incidência de um feixe de laser pulsado de nitrogênio em um eletrodo (catodo) de alumínio. O anodo de vidro de alta resistividade (ρ = 2 x 1012Ω.cm) protege o detector contra descargas disruptivas. Para validação inicial do método, a comparação entre as correntes elétricas medidas nos regimes de ionização e de avalanche foi usada na determinação dos valores de α no nitrogênio, gás amplamente estudado com dados bem estabelecidos na literatura. Esta técnica foi estendida com sucesso para obtenção do parâmetro α para o isobutano puro. A presença de efeitos relativos à carga espacial, recombinação e à queda ôhmica através do anodo resistivo foi investigada mediante variação da taxa de repetição do feixe de laser, de sua intensidade e do campo elétrico aplicado. Destes processos secundários, somente a queda ôhmica mostrou-se relevante e os valores de campo elétrico reduzido foram corrigidos para este efeito. Os primeiros coeficientes de Townsend obtidos são compatíveis, dentro do erro experimental, com os determinados com o programa Magboltz 2 versões 7.1 e 8.6. / In this work are presented data of Townsend first ionization coefficient, α, in pure isobutane, obtained with a parallel plate chamber of resistive anode, for the reduced electric field range of 140 Td up to 230 Td. The adopted method is based on a new version of the Pulsed Townsend Technique, where the primary ionization is produced by the incidence of nitrogen pulsed laser beam in an aluminum electrode (cathode). The glass anode of high resistivity (ρ = 2 x 1012 Ω.cm) protects the detector against sparks. To validate the method, the α values were determined by comparing the ionization and avalanche electric currents in nitrogen, gas widely studied with well-established data in literature. This technique was successfully extended to obtain α parameters in pure isobutane. The presence of effects related to spatial charge, recombination and ohmic drop across the resistive anode was investigated by varying laser pulse repetition rate, its intensity and applied electric field. Of these secondary processes, only the ohmic drop was relevant and the reduced electric field values were corrected for it. The first Townsend coefficients obtained are compatible, within the experimental errors, with those determined with Magboltz 2 program versions 7.1 e 8.6.
12

Deepwater

Carrasco, Katrina Marie 03 June 2015 (has links)
DEEPWATER is a novel that takes place in Port Townsend, Washington Territory, in 1887. This thesis contains the first sections of the novel, in which detective Alma Rosales goes undercover to infiltrate an opium-smuggling ring. She arrives in the remote outpost where the ring operates, falls in with some waterfront thieves, and gets to work. Soon it becomes apparent that Alma's reports to her Pinkerton employers aren't telling the whole truth. And as she gets cozier with the outlaws of Port Townsend, Alma's own identity and motives come into question. Thematically this novel is an exploration of constructed identity: the many parts one person plays in her daily life and over time, and how some parts become habit while others may never feel natural. Alma's disguises make explicit her various performances of personality, physicality and gender. Stylistically I've chosen to reflect Alma's personas, performed or otherwise, in corresponding narrative modes (points of view). Also explored are the performative aspects of dialogue, the blending or warping of genres and genre expectations, and the experience of inhabiting a physical body that is sometimes wildly at odds with the mind.
13

Medidas do primeiro coeficiente de Townsend de ionização em misturas gasosas utilizadas em microdosimetria / Measurements of the first Townsend ionization coefficient in gaseous mixtures employed in microdosimetry

Petri, Anna Raquel 17 April 2017 (has links)
Microdosímetros gasosos geralmente empregam uma mistura gasosa equivalente ao tecido humano mole (Tissue-equivalent Gas TEG), composta de um hidrocarboneto, dióxido de carbono e nitrogênio, de forma que o poder de freamento na mistura e no tecido sejam semelhantes. Entretanto, independentemente do hidrocarboneto adotado, dados tanto teóricos como experimentais do primeiro coeficiente de Townsend de ionização (α) nestas misturas são raros, ainda que a primeira TEG, cujo metano é o gás majoritário, tenha sido proposta em 1956 por Rossi e Failla e continue sendo amplamente utilizada. Neste trabalho, dados do parâmetro α em TEGs baseadas no metano (CH4 64,4%, CO2 32,4% e N2 3,2%) e nos isômeros do butano (C4H10 51,4%, CO2 42,3% e N2 6,3%) são apresentados pela primeira vez em geometria planar para a faixa de campo elétrico normalizado pela densidade do gás (E/N) entre 100 290 Td (1 Td = 10-21 V.m2). O método de medidas adotado baseia-se na técnica de Townsend pulsada, onde o primeiro coeficiente de Townsend pode ser determinando comparando a corrente elétrica no regime de avalanche e a corrente de ionização primária gerada pela incidência de um feixe de laser de nitrogênio em um eletrodo metálico (catodo) de uma câmara de geometria planar, sendo o anodo um eletrodo de alta resistividade (ρ=2×1010Ω.m). O aparato experimental, até então operado apenas em pressão atmosférica, foi modificado para também trabalhar em baixa pressão (120 hPa), de modo a aumentar a faixa de E/N investigada. A validação do método e das alterações do sistema de detecção foi realizada utilizando os três gases componentes das TEGs cujos parâmetros de transporte são amplamente estudados: o nitrogênio, o dióxido de carbono e o metano. Observou-se que o parâmetro na TEG com metano assemelha-se com os valores determinados para o metano puro. Na TEG baseada no isobutano, ele é compatível com o primeiro coeficiente de Townsend do dióxido de carbono para campos acima de 170 Td. Já o parâmetro na mistura com n-butano é intermediário entre os valores obtidos para o dióxido de carbono e o nitrogênio. Os resultados experimentais, disponíveis em forma tabular, foram comparados com os simulados utilizando o programa Magboltz 2, evidenciando boa concordância dentro da incerteza experimental. / Gaseous microdosimeters usually employ a Tissue-equivalent Gas (TEG), made of a hydrocarbon, carbon dioxide and nitrogen, in order to make similar the stopping power in this mixture and in the human soft tissue. Notwithstanding, regardless the chosen hydrocarbon, both theoretical and experimental data on the first Townsend ionization coefficient (α) in this mixtures are rare, even though the first TEG, which methane is the most abundant gas, was proposed in 1956 by Rossi and Failla and it has been widely employed since then. In this work, data on the parameter α in TEGs based on methane (CH4 64.4%, CO2 32.4%, and N2 3.2%) and butanes isomers (C4H10 51.4%, CO2 42.3% e N2 6.3%) are presented for the first time in planar geometry in the gas density-normalized electric field (E/N) range between 100 290 Td (1 Td = 10-21 V.m2). The adopted method is based on the Pulsed Townsend Technique, where the first Townsend coefficient can be determined by comparing the electric current in the avalanche mode and the primary ionization current, produced by an nitrogen laser beam incidence in a metallic electrode (cathode) of a parallel plate chamber, which the anode is a resistive electrode (ρ=2×1010Ω.m). The experimental setup, previously operated only at atmospheric pressure, was adapted to work also at low pressure (120 hPa), in order to increase the investigated E/N range. The validation of both method and detection system modifications was made by employing three TEGs components, nitrogen, carbon dioxide and methane, whose transport parameters are extensively studied. The parameter in the methane-based TEG follows the behavior observed in pure methane. In the isobutane-based TEG, it is compatible with the first Townsend coefficient in carbon dioxide for E/N above 170 Td. The parameter in the n-butane-based TEG lies between the obtained values of in carbon dioxide and nitrogen. The experimental results, included in tabular form, agree with those from Magboltz 2 simulations within the experimental uncertainties.
14

Medidas do primeiro coeficiente de Townsend de ionização em misturas gasosas utilizadas em microdosimetria / Measurements of the first Townsend ionization coefficient in gaseous mixtures employed in microdosimetry

Anna Raquel Petri 17 April 2017 (has links)
Microdosímetros gasosos geralmente empregam uma mistura gasosa equivalente ao tecido humano mole (Tissue-equivalent Gas TEG), composta de um hidrocarboneto, dióxido de carbono e nitrogênio, de forma que o poder de freamento na mistura e no tecido sejam semelhantes. Entretanto, independentemente do hidrocarboneto adotado, dados tanto teóricos como experimentais do primeiro coeficiente de Townsend de ionização (α) nestas misturas são raros, ainda que a primeira TEG, cujo metano é o gás majoritário, tenha sido proposta em 1956 por Rossi e Failla e continue sendo amplamente utilizada. Neste trabalho, dados do parâmetro α em TEGs baseadas no metano (CH4 64,4%, CO2 32,4% e N2 3,2%) e nos isômeros do butano (C4H10 51,4%, CO2 42,3% e N2 6,3%) são apresentados pela primeira vez em geometria planar para a faixa de campo elétrico normalizado pela densidade do gás (E/N) entre 100 290 Td (1 Td = 10-21 V.m2). O método de medidas adotado baseia-se na técnica de Townsend pulsada, onde o primeiro coeficiente de Townsend pode ser determinando comparando a corrente elétrica no regime de avalanche e a corrente de ionização primária gerada pela incidência de um feixe de laser de nitrogênio em um eletrodo metálico (catodo) de uma câmara de geometria planar, sendo o anodo um eletrodo de alta resistividade (ρ=2×1010Ω.m). O aparato experimental, até então operado apenas em pressão atmosférica, foi modificado para também trabalhar em baixa pressão (120 hPa), de modo a aumentar a faixa de E/N investigada. A validação do método e das alterações do sistema de detecção foi realizada utilizando os três gases componentes das TEGs cujos parâmetros de transporte são amplamente estudados: o nitrogênio, o dióxido de carbono e o metano. Observou-se que o parâmetro na TEG com metano assemelha-se com os valores determinados para o metano puro. Na TEG baseada no isobutano, ele é compatível com o primeiro coeficiente de Townsend do dióxido de carbono para campos acima de 170 Td. Já o parâmetro na mistura com n-butano é intermediário entre os valores obtidos para o dióxido de carbono e o nitrogênio. Os resultados experimentais, disponíveis em forma tabular, foram comparados com os simulados utilizando o programa Magboltz 2, evidenciando boa concordância dentro da incerteza experimental. / Gaseous microdosimeters usually employ a Tissue-equivalent Gas (TEG), made of a hydrocarbon, carbon dioxide and nitrogen, in order to make similar the stopping power in this mixture and in the human soft tissue. Notwithstanding, regardless the chosen hydrocarbon, both theoretical and experimental data on the first Townsend ionization coefficient (α) in this mixtures are rare, even though the first TEG, which methane is the most abundant gas, was proposed in 1956 by Rossi and Failla and it has been widely employed since then. In this work, data on the parameter α in TEGs based on methane (CH4 64.4%, CO2 32.4%, and N2 3.2%) and butanes isomers (C4H10 51.4%, CO2 42.3% e N2 6.3%) are presented for the first time in planar geometry in the gas density-normalized electric field (E/N) range between 100 290 Td (1 Td = 10-21 V.m2). The adopted method is based on the Pulsed Townsend Technique, where the first Townsend coefficient can be determined by comparing the electric current in the avalanche mode and the primary ionization current, produced by an nitrogen laser beam incidence in a metallic electrode (cathode) of a parallel plate chamber, which the anode is a resistive electrode (ρ=2×1010Ω.m). The experimental setup, previously operated only at atmospheric pressure, was adapted to work also at low pressure (120 hPa), in order to increase the investigated E/N range. The validation of both method and detection system modifications was made by employing three TEGs components, nitrogen, carbon dioxide and methane, whose transport parameters are extensively studied. The parameter in the methane-based TEG follows the behavior observed in pure methane. In the isobutane-based TEG, it is compatible with the first Townsend coefficient in carbon dioxide for E/N above 170 Td. The parameter in the n-butane-based TEG lies between the obtained values of in carbon dioxide and nitrogen. The experimental results, included in tabular form, agree with those from Magboltz 2 simulations within the experimental uncertainties.
15

Avalanche multiplication and breakdown in wide bandgap semiconductors

Ghin, Raymond January 1998 (has links)
No description available.
16

The Gift of Death, or, Beyond the Beneficent Spider : a novel & associated critical exposition

Tew, Philip January 2016 (has links)
This thesis has three main sections, the first a full-length novel entitled The Gift of Death, the third the bibliography and two appendices. The second contains variously: a preface; a critical exposition/analysis of the preceding novel with subsections, considering in conceptual fashion three central themes: death considered through symbolic, ideological and other meanings; a positioning of the academy in the ‘Campus’ novel sub-genre; and a socio-cultural analysis of fiction as a field of production and associated struggles for entry determined by class, origin and periodic cultural preferences. The Gift of Death concerns a sixty-year-old’s attempt to write a novel. Procrastinating English scholar, archetypal baby-boomer Jim Dent, revisits the thwarted ambitions of youth. Inspired by novelist Sue Townsend’s death, once a friend, Jim recalls knowing other aspirant artists—writers and film-makers— living and dying in obscurity. He reflects upon a troubled past, on unsatisfactory elements of the present and the increasingly daunting task of composition. The Gift of Death reworks the tradition of the campus or varsity novel, detailing lives tied to the rhythms of the academy. The chapters explore various eccentrics whose lives Jim traces through tentative, inadequate notes. Expanding such recollections the narrative includes: schooldays; postgraduate studies and school-teaching in Leicester; a voyage to interview Basil Bunting; and friendships with oddball alcoholics writers, Cedric and Challis, never satisfied or fully recognized creatively. Finally, overwhelmed by self-doubt, Jim abandons his Sisyphean task. Reflecting upon failure, an unexpected turn of events associated with visiting Bunting emerges in the present, offering resolution of sorts. The Gift of Death’s primary themes/contexts are: self-reflexive, multi-chronic form; death, loss and mourning; the baby-boomer generation; struggling for professional entry into the field of fiction; lost provincial and local creativity; the juxtaposition of past and present; loyalty, friendship and memory; parental conflict; and finally procrastination and disappointment.
17

Formation and function of industrial districts in the rural Northwest : two cases /

Fossum, Harold L. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 277-289).
18

Lithic resource survey of the upper Little River drainage raw material availability and use at the Townsend sites /

Sweat, Jeremy Lee, January 2009 (has links)
Thesis (M.A.)--University of Tennessee, Knoxville, 2009. / Title from title page screen (viewed on Mar. 3, 2010). Thesis advisor: Boyce N. Driskell. Vita. Includes bibliographical references.
19

Forms of feminist writing, 1914-1939 : West, Warner, Woolf, and the cultural context /

Avasthi, Smita, January 1999 (has links)
Thesis (Ph. D.)--University of Oregon, 1999. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 237-258). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9955910.
20

Revisão das espécies neotropicais de Chaetoravinia Townsend, 1917 (Diptera, Sarcophagidae)

Guimarães , Hugo José Lopes 17 April 1998 (has links)
Submitted by Alberto Vieira (martins_vieira@ibest.com.br) on 2018-05-24T20:52:53Z No. of bitstreams: 1 278404.pdf: 7796589 bytes, checksum: ed079599aeacc6d3463f153f105b39d0 (MD5) / Made available in DSpace on 2018-05-24T20:52:53Z (GMT). No. of bitstreams: 1 278404.pdf: 7796589 bytes, checksum: ed079599aeacc6d3463f153f105b39d0 (MD5) Previous issue date: 1998-04-17 / CAPES / Essa dissertação apresenta a revisão taxonômica das espécies neotropicais de Chaetoravinia Townsend, 1917 (Diptera, Sarcophagidae). Segundo DODGE (1968) e LOPES (1969, 1976, 1977, 1978) na região neotropical são reconhecidas dez espécies: Chaetoravinia advena (Walker, 1852), Chaetoravinia almeidai Lopes, 1946, Chaetoravinia barroi Dodge, 1956, Chaetoravinia dampfi Lopes, 1946, Chaetoravinia derelicta (Walker, 1852), Chaetoravinia effrenata (Walker, 1861), Chaetoravinia errabunda (Wulp, 1895), Chaetoravinia globulus (Aldrich, 1916), Chaetoravinia postnoda Dodge, 1968 e Chaetoravinia vagabunda (Wulp, 1895). Redescrições dos machos de todas as espécies são apresentadas, acompanhadas de ilustrações da terminália, incluindo caracteres relevantes na definição das espécies, não mencionados por autores anteriores, em descrições ou revisões, tais como: hillae, haste dorsal e processo mediano. Também é apresentada uma chave para identificação dos machos das espécies neotropicais de Chaetoravinia. Através do estudo detalhado da terminália masculina foram reconhecidos dois grupos informais de espécies com base nas similaridades morfológicas: "grupo advena" e "grupo derelicta". / This dissertation presents the taxonomic revision of the neotropical species of Chaetoravinia Townsend, 1917 (Diptera, Sarcophagidae ). According to DODGE (1968) and LOPES (1969, 1976, 1977, 1978) ten species are recognized to the neotropical region: Chaetoravinia advena (Walker, 1852), Chaetoravinia almeidai Lopes, 1946, Chaetoravinia barroi Dodge, 1956, Chaetoravinia dampfi Lopes, 1946, Chaetoravinia derelicta (Walker, 1852), Chaetoravinia effrenata (Walker, 1861), Chaetoravinia errabunda (Wulp, 1895), Chaetoravinia globulus (Aldrich, 1916), Chaetoravinia postnoda Dodge, 1968 and Chaetoravinia vagabunda (Wulp, 1895). Male redescriptions are presented and are accompanied by the terminalia illustrations, including important characteres used in the definition of the species, not mentioned by the former authors in their descriptions or revisions, as: hillae, dorsal rods and median process. A key for male identification of the neotropical species of Chaetoravinia is also presented. According to the detailed study of the male terrninalia, two informal groups of species were recognized based on the morfological similarities: "advena group" and "derelicta group".

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