Some aspects of the barotropic instability of continental boundary currents are investigated herein. In the first problem, a piecewise linear wall-jet is perturbed by the most unstable linear mode and the nonlinear evolution of the disturbance is computed. It is shown that the eddies in the wall-jet case evolve much differently than those resulting from the instability of a free jet. This simple model illustrates that even without dissipative processes, a rapid diffusion of mean momentum and vorticity occurs. This contrasts with the main result of this study presented in the second problem where it is argued that the use of a classical eddy parametrization in the analysis of continental boundary currents leading to the diffusion of momentum and relative vorticity fails to recognize that the relevant eddies are dominated by the conservation of potential vorticity, which in turn may produce an increase in the mean relative vorticity. To illustrate this effect, we examine a non-inflected barotropic shear flow destabilized by the cross stream variation in the bottom topography of a continental slope. The finite amplitude evolution of the waves is analyzed in a simple model with a steplike bottom topography and with piecewise uniform potential vorticity distribution. The increase in maximum mean vorticity is computed for various values of the Rossby number and the topographic elevation, and it is suggested that a similar effect, taking into account the isopycnal topography as well as the isobaths, could maintain the large inshore shear of the Gulf Stream. Cross shelf transport of different water types (i.e.: potential vorticity and passive tracers) are also computed and suggested to be pertinent to the more realistic oceanic problem involving baroclinic effects. The numerical calculation employs the well known method of contour dynamics, and the Green's function appropriate for the step-like topography is derived. / Source: Dissertation Abstracts International, Volume: 54-07, Section: B, page: 3531. / Major Professor: Melvin E. Stern. / Thesis (Ph.D.)--The Florida State University, 1993.

The upstream propagating acoustic waves and Kelvin-Helmholtz instability waves associated with supersonic twin jets are investigated using a vortex sheet mode. For the instability waves, a second model which takes into account the finite thickness of the jet mixing layer is also used. For each jet model, dispersion relations of the instability and acoustic saves are derived. The eigenvalues and eigenfunctions are classified into four linearly independent families according to the symmetry of eigenfunctions. Within each family there are an infinite number of modes. / A parametric study of the acoustic and instability wave eigenvalues and eigenfunctions has been carried out. Numerical results of the total growths show that the most unstable wave mode for each family is the flapping mode. Under a given operating condition, the flapping modes of family 1 and family 2 are the most dominant. It is found that the wave frequencies of the upstream propagating acoustic waves are confined to narrow bands. Formulas of cutoff points of dispersion curves of upstream propagating acoustic waves are derived. These formulas can be used to provide a first estimate of the screech tones frequencies of twin supersonic jets. / Source: Dissertation Abstracts International, Volume: 54-11, Section: B, page: 5755. / Major Professor: Christopher K. W. Tam. / Thesis (Ph.D.)--The Florida State University, 1993.

A method for calculating the acoustic radiation generated by the large scale instabilities of axisymmetric jets is developed. The characteristics of the flow instabilities are obtained from the linearized, inviscid, compressible equations of motion in terms of an asymptotic expansion. This asymptotic expansion is not uniformly valid far away from the jet flow. To obtain a solution valid far away from the jet, the method of matched asymptotic expansions is used. The matching of inner and outer solutions provide two very important results. First, a new interpretation of the eigenvalue problem of classical instability theory is given. Secondly, matching provides a method for determining the slow varying wave amplitude of the instability wave allowing for a complete spatial description of the instability wave to order unity. Calculations of the instability wave characteristics, near- and far-field pressure fluctuations for an unheated, ideally expanded, moderate Reynolds number jet with jet exit Mach number of 2.1 are performed at several frequencies and for the axisymmetric and helical instabilities. The numerical results of this model are then compared with experiments and good agreement is found in both the jet flow and near-field. / Source: Dissertation Abstracts International, Volume: 42-10, Section: B, page: 4099. / Thesis (Ph.D.)--The Florida State University, 1981.

Em âmbito hospitalar é crescente o emprego de dispositivos confeccionados de distintos materiais termossensíveis. Assim, o emprego de metodologias esterilizantes compatíveis tem sido o foco de muitas pesquisas, dentre as quais destacam-se estudos envolvendo o plasma. O mecanismo de ação deste desenvolve-se com a aplicação de Rádio-Freqüência a gases precursores, resultando na inativação microbiana por espécies altamente reativas. Este método inovador caracteriza-se por não gerar riscos de toxicidade ocupacional e aos pacientes, e ser processado em temperatura próxima ao ambiente. Para análise comparativa foi utilizado o método de esterilização por óxido de etileno (agente químico na forma gasosa). Este gás apresenta características de elevada inflamabilidade, explosividade e toxicidade, por isso é usado diluído em gases inertes, além de deixar residual no material esterilizado, tendo que ter um controle rigoroso no processo de aeração; porém atualmente é um dos métodos mais utilizados para esterilização de materiais odonto-médico-hospitalares, particularmente os termossensíveis. O principal objetivo deste trabalho foi estudar diferentes parâmetros do processo e seus respectivos resultados, que influenciam na esterilização empregando plasma e compará-los com os obtidos empregando óxido de etileno. O equipamento utilizado para o estudo dos processos de esterilização por plasma foi o ICP (Inductively Coupled Plasma). Analisou-se assim para o plasma algumas distintas combinações de parâmetros, tais como: gases (oxigênio puro e mistura deste com peróxido de hidrogênio a 5,10 e 20%), pressão (330 mTor), vazão do gás (100sccm), temperatura (próxima ao ambiente), potência de rádio-freqüência (300, 350 e 400W), tempos de exposição (com intervalos de 3 a 60 min) e umidade relativa (80±5%). No ICP foram desenvolvidas duas fases planejadas para os processos, seguindo uma programação experimental, já no óxido de etileno foram realizadas três séries de exposições sub–letais utilizando mistura esterilizante Oxyfume® 2002 (10% Óxido de Etileno, 63% HCFC 124 e 27% HCFC 22), sendo os parâmetros padronizados: umidade relativa (40 a 60%), concentração do gás (450 mg/L), temperatura (55° C) e tempos de exposição (com intervalos de 3 a 15 min.). Todos os ciclos foram realizados em triplicata. Esporos de Bacillus subtilis var. niger ATCC 9372 foram obtidos a partir de suspensões de microrganismos e inoculados em suportes na concentração de 107 UFC/suporte para serem utilizados nos estudos dos processos de esterilização. Empregou-se a técnica de Pour Plate (incubação em estufa por 24hs a 37 °C) para a quantificação dos esporos. Para o processo de esterilização por plasma os resultados obtidos forneceram valores D que variaram entre 8 e 3 min., dependendo dos parâmetros testados, e para o processo de esterilização por óxido de etileno o Valor D foi de 2,80 min. Concluiu-se que o processo de esterilização por plasma apresentou resultados interessantes e promissores e os melhores resultados foram obtidos com as potências maiores de 350 e 400W para o gás oxigênio puro, caracterizando o plasma como alternativa promissora de esterilização, devido às suas características positivas frente ao óxido de etileno, pois os valores D entre os dois processos de esterilização não apresentaram uma diferença significativa. / The gas Plasma sterilization technology has been emerging as an alternative to conventional low temperature processes since the advent of new therapies using heat sensitive materials in the healthcare field is greater than ever. The gas Plasma mechanism of action includes the generation of actives species by an electrical discharge, which is able to promote lethal effect on microorganisms. The sterilization techniques using gas plasma are under intense investigation and it has already been demonstrated by recent studies that this technology is simple, cost-effective, suitable for microbicidal activity and absent of toxic residuals. Ethylene oxide is the sterilization agent most widely applied to medical devices. However, its explosiveness, inflammability and toxicity led to the search for other sterilization methods at low temperature and it has been used associated to non active gases which inhibit these properties and it is necessary to have the control at the occupational safety and environmental monitoration. Therefore, the aim of this work was to explore possible microbicidal application of the gas plasma sterilization generated by an inductively coupled system and to compare this sterilization method with ethylene oxide (chemistry substance in gaseous form), observing their D value. It was used distinct combinations of process parameters to sterilization by plasma, as follows: radio-frequency powers (300, 350 and 400 watts), exposition times (in the range of 3 to 60 minutes), gas (pure oxygen and mixture with hydrogen peroxide 5,10 and 20%), gas flow (100 sccm), pressure (330 mTorr), temperature (close to the environmental one) and relative humidity 80±5%. For ethylene oxide, Oxyfume 2002® was used (mixture of ethylene oxide, HCFCs 22 and 124), under the concentration of 450mg/L, at the temperature of 55°C and relative humidity of 50±5% and it was submitted to a time of exposition between 3 to 15 minutes. Both processes were submitted to exposition cycles in triple. Bacillus subtilis var. niger ATCC 9372 inoculated in a standard load of 107 spores per carrier was used as biological indicator. After the exposition, the biological indicator\'s spore survivors were counted by the \"Pour Plate\" technique (incubation temperature of 35 ± 2ºC for 24 hours). Significant microbial reduction was observed in some cases where the plasma D value was between 3 and 8 min and 3,08 min, 3,04 min. to 350 and 400W powers respectively. In the ethylene oxide process the D value was 2,80 min. These results evidenced the higher effectiveness of ethylene oxide comparatively to plasma. However the latter presents advantages that make it an interesting alternative to low temperature sterilization processes.

by Tsui Chi Wa. / Chinese title: / Bibliography: leaf 51 / Thesis (M.Phil.) -- Chinese University of Hong Kong, 1983

by Chan Pui-King. / Bibliography: leaf 45 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

by Ng Chi Shing. / Chinese title in romanization: Shao sheng bo zai deng li zi ti guan dao nei di fei fa san zhuan bo. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1987. / Bibliography: leaf 70.

by Tong Shiu Sing Dominic. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 242-245). / Acknowledgements --- p.iv / Abstract --- p.v / Chapter I --- Introduction --- p.1 / Chapter 1.1 --- A general review of the theory --- p.1 / Chapter 1.2 --- An outline of this thesis --- p.6 / Chapter II --- Dispersion surfaces of cold magnetoplasmas --- p.9 / Chapter 2.1 --- Meaning of dispersion surface and wavevector surface --- p.9 / Chapter 2.2 --- Dispersion surfaces of a two component electron-ion magnetoplasma --- p.13 / Chapter 2.3 --- Dispersion surfaces of a three component electron-ion-positron magnetoplasma --- p.35 / Chapter 2.4 --- Dispersion surfaces of a three component electron-ions magnetoplasma --- p.50 / Chapter 2.5 --- Doppler shifted wavevector surfaces (DWS) --- p.61 / Chapter A. --- Examples of DWS in an isotropic cold plasma --- p.61 / Chapter B. --- Examples of DWS in a cold magnetoplasma --- p.62 / Chapter 2.6 --- Dispersive surfaces of a moving magnetoplasma --- p.63 / Chapter III --- Evaluation of far field caused by a moving source --- p.72 / Chapter 3.1 --- Maxwell's equations and constitutive relations --- p.72 / Chapter 3.2 --- Calculation of far field by Lai and Chan's method --- p.75 / Chapter 3.3 --- Radiation energy flow --- p.85 / Chapter IV --- Controversy of Lai and Chan's method --- p.94 / Chapter 4.1 --- Origin of the controversy --- p.94 / Chapter 4.2 --- Evaluating the far field by the method of other authors --- p.97 / Chapter 4.3 --- "Comparsion of the fields found by Lai, Chan and other authors" --- p.100 / Chapter A. --- Comparing the far fields in an uniaxial non-dispersive medium --- p.101 / Chapter B. --- Comparing the far fields in an isotropic cold plasma --- p.104 / Chapter 4.4 --- Some remarks on the method of stationary phase --- p.109 / Chapter V --- Gyro-radiation in a cold magnetoplasma --- p.113 / Chapter 5.1 --- Introduction --- p.113 / Chapter 5.2 --- Radiation energy flux caused by a moving dipole in a magnetoplasma --- p.115 / Chapter 5.3 --- Radiation energy flux caused by a gyrating electron in a magnetoplasma --- p.135 / Chapter VI --- The ratio of emitted to received power in a magnetoplasma --- p.186 / Chapter 6.1 --- Introduction --- p.186 / Chapter 6.2 --- Methol of calculating the ratio of emitted to received power --- p.187 / Chapter 6.3 --- Numerical examples of the power ratio in a magnetoplasma --- p.191 / Chapter VII --- Evaluation of far field in a moving medium --- p.199 / Chapter 7.1 --- Introduction --- p.199 / Chapter 7.2 --- Far field expression in a moving medium --- p.200 / Chapter 7.3 --- Relation between Lai and Chan's far field and the far field in a moving medium --- p.206 / Chapter VIII --- Radiation in some moving media --- p.216 / Chapter 8.1 --- Introduction --- p.216 / Chapter 8.2 --- Radiation in a moving isotropic non- dispersive medium --- p.216 / Chapter 8.3 --- Radiation in a moving isotropic cold plasma --- p.223 / Chapter 8.4 --- Radiation in a moving cold magnetoplasma --- p.226 / Chapter IX --- Conclusions --- p.232 / Appendix A --- p.235 / Appendix B --- p.238 / Appendix C --- p.241 / References --- p.242

Le traitement des eaux industrielles usées est un enjeu pour la société. Notamment, les colorants très utilisés dans les produits manufacturés sont des polluants pour nos sources d'eau. Ce travail de thèse porte sur la dégradation de colorant(s) par un système de couche mince nanocomposite cuivre/carbone. Nos nanocomposites ont été élaborés grâce à un procédé plasma par pulvérisation cathodique en atmosphère réactive de cyclohexane (ou procédés hybride PVD/PECVD dépendant). Des études par spectroscopie d'émission optique et spectrométrie de masse ont été menées afin d'analyser le plasma lors de la phase de dépôt. Après leur synthèse, nos couches minces ont été caractérisées d'un point de vue structural (morphologie et microstructure), optique et électrique en fonction de différents paramètres de dépôt. Dans ce travail, le polluant utilisé est le carmin d'indigo classé dans la famille des indigoïdes célèbre pour la couleur bleu des jeans. Le suivi de la dégradation de ce colorant en solution aqueuse a été réalisé par spectrophotométrie UV-visible. Nos nanocomposites ont pu décolorer les solutions lors d'une illumination par une lampe halogène ou lors d'une phase de chauffage. Nous nous sommes intéressés à l'étude thermique de ce phénomène en fonction de différents paramètres (température, concentration initiale,…) et aux modèles thermodynamiques de cette réaction (Eyring et Arrhénius). Pour justifier la dégradation du colorant, un électro-nébuliseur couplé à un spectromètre de masse a été utilisé. Cette expérimentation montre que la molécule de carmin d'indigo a subi une perte de masse et que nos matériaux se comportent bien en catalyseurs / The treatment of industrial wastewater is an issue for the society. For instance, used dyes in manufactured products are pollutants for our waters sources. The thesis work focuses on dye degradation by thin films of copper/carbon nanocomposite. Our nanocomposites have been elaborated through a plasma method by a cathodic sputtering in reactive atmosphere of cyclohexane (hybrid process of PVD/PECVD). Studies by optical emission spectroscopy and mass spectroscopy have been carried out in order to analyze the plasma during the deposition. After elaboration, our thin films have been characterized from a structural (morphology and microstructure), electrical and optical point of view as a function of deposit parameters. In this work, we used indigo carmine as a pollutant. The dye belongs to the indigoid family and is commonly used for the blue color of jeans. The degradation of this dye in aqueous solutions has been monitored by UV-Visible spectrophotometry. Our nanocomposites have been able to discolour solutions by halogen lamp illumination or during moderate heating. The investigation focused on the thermal aspects of this phenomenon as a function of several parameters (temperature, initial concentration,…) with the help of thermodynamic models such as Arrhenius and Eyring. To justify the degradation of the dye, an electrospray ionization mass spectrometer has been used. It revealed that the molecule of indigo carmine underwent a loss of mass and that our materials perform as catalysts

Orientador: Helmut Karl Bockelmann / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-09-26T18:15:00Z (GMT). No. of bitstreams: 1 Honda_RobertoYzumi_M.pdf: 2897598 bytes, checksum: 767831d18946944a21ba24f4b4fe631f (MD5) Previous issue date: 1980 / Resumo: Foi construído um sistema q-pinch de 2kJ de energia provido de sistemas auxiliares de pré-ionização. Efetuou-se um estudo experimental e teórico do plasma produzido (plasma de Hélio) e do sistema q-pinch em si, utilizando-se para tal um modelo teórico já desenvolvido (referência l91) e de três técnicas experimentais distintas. a) Sondas Magnéticas b) Espectroscopia no Visível (OMA) c) Fotografia ultra rápida (IMACON) Com as sondas magnéticas foram determinados os parâmetros elétricos do sistema. O diagnóstico do plasma gerado foi efetuado através do estudo do perfil da linha l0 = 4686 Å (HeII), utilizando-se os Alargamentos Doppler e Stark para a determinação da temperatura iônica e da densidade eletrônica respectivamente. Obteve-se a evolução temporal destes parâmetros com a utilização do OMA (Optical Multichannel Analyzer) operando no modo pulsado. Utilizou-se a câmera especial lMACON para o estado da dinâmica do sistema q -pinch e observou-se instabilidades na coluna do plasma gerado. Obteve-se uma boa concordância entre os valores teóricos e experimentais / Abstract: A q-pinch system has been constructed with preheating devices with a total energy of 2 kJ. During this experiment a He Plasma was studied using the following three different diagnostics. a) Magnetic Probes b) Visible Spectroscopy using the Optical Multichannel Analyzer -OMA c) Image Converter Camera. The experimental results have been checked with existing theoretical models. The electrical characteristics of the system were determined with the magnetic probe. The Doppler and Stark broadening effects of the l 0 = 4686 Å (HeII) have been used to determine the ionic temperature and electronic density respectively. The time evolution of these parameters was obtained using the OMA. The dynamics of the plasma were observed by high speed photography. Instabilities in the plasma columm have been observed. Good agreement between the experimental and theoretical values was obtained / Mestrado / Física / Mestre em Física