Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

O presente estudo comparou os efeitos da raquianestesia com o anestésico local bupivacaína isobárica a 0,5% isolado ou associado ao agonista alfa adrenérgico clonidina em gatas anestesiadas com propofol e isofluorano para realização de ovariosalpingohisterectomia. Trinta gatas foram pré-tratadas com meperidina; decorridos 15 minutos, a indução da anestesia foi realizada com propofol, seguido de isofluorano para manutenção anestésica. As gatas foram distribuídas em três grupos, onde receberam, na raquianestesia: solução fisiológica (GSF); bupivacaína isobárica (GB), ou bupivacaína isobárica e clonidina (GBC). Todos os animais foram submetidos a ovariosalpingohisterectomia. As frequências cardíaca e respiratória, pressão arterial e temperatura retal foram mensuradas durante todos os momentos de avaliação. Durante a anestesia, foram incluídas as análises da fração expirada de dióxido de carbono, fração expirada de isofluorano e saturação da oxihemoglobina periférica. A hemogasometria foi realizada previamente a raquianestesia a ao término do procedimento cirúrgico. O grau de sedação, foi analisado no período de recuperação com auxílio de escore A raquianestesia com bupivacaína e clonidina não promoveu alterações na frequência e ritmo cardíaco, pressão arterial nem depressão respiratória tendo em vista que os valores de frequência respiratória e fração expirada de dóxido de carbono permaneceram dentro dos valores fisiológicos. O emprego de bupivacaína isolada e em associação à clonidina promoveu redução da concentração expirada de isofluorano (respectivamente 63,5% e 70) quando comparados ao grupo controle. O uso de clonidina determinou sedação no período de recuperação. O uso da raquianestesia com bupivacaína isobárica a 0,5% isolada ou em associação à clonidina demonstrou boa estabilidade hemodinâmica e significativa diminuição no requerimento de anestésico geral; a clonidina potencializou o efeito da bupivacaína isobárica no momento cirúrgico e apresentou grau satisfatório de sedação no período pós operatório / This study compares effects of spinal anesthesia with isobaric bupivacaine at 0,5% either isolated or associated to clonidine administered to female cats undergoing ovariohysterectomy under the effect of propofol and isoflurane. Meperidine was administered to thirty female cats whose anesthetic induction was performed 15 minutes later with the help of propofol followed by isoflurane for maintenance of anesthesia. The female cats were split into three different groups which received one of the following substances each for spinal anesthesia: physiological saline solution (GSF); isobaric bupivacaine (GB); isobaric bupivacaine and clonidine (GBC). All thirty animals underwent ovariohysterectomy. Heart and respiratory rate, blood pressure and rectal temperature were measured throughout the procedures. Under anesthesia, the fraction of expired carbon dioxide, the fraction of expired isoflurane and the saturation of oxihemoglobin were analyzed. Arterial blood gasometry was performed before spinal anesthesia and after surgical procedures. The level of sedation was analyzed during recovery with the help of scores from Selmi et al. (2004) Spinal anesthesia associated to bupivacaine and clonidine did not alter the heart rate, blood pressure or respiratory depression once the respiratory rate numbers and the fraction of expired carbon dioxide numbers ranged within the normal physiological values. The use of bupivacaine, either isolated or associated to clonidine, led to the reduction of the concentration of expired isoflurane (63,5% and 70% respectively) when compared to the control group. The use of clonidine led to sedation during recovery. The use of spinal anesthesia combined with isobaric bupivacaine at 0,5%, isolated or associated to clonidine, demonstrated good hemodynamic stability and a significant decrease in the need of general anesthesia; clonidine optimized the effect of isobaric bupivacaine throughout surgical procedures and also showed a satisfactory level of sedation during the postoperative period

O presente estudo comparou os efeitos da raquianestesia com o anestésico local bupivacaína isobárica a 0,5% isolado ou associado ao agonista alfa adrenérgico clonidina em gatas anestesiadas com propofol e isofluorano para realização de ovariosalpingohisterectomia. Trinta gatas foram pré-tratadas com meperidina; decorridos 15 minutos, a indução da anestesia foi realizada com propofol, seguido de isofluorano para manutenção anestésica. As gatas foram distribuídas em três grupos, onde receberam, na raquianestesia: solução fisiológica (GSF); bupivacaína isobárica (GB), ou bupivacaína isobárica e clonidina (GBC). Todos os animais foram submetidos a ovariosalpingohisterectomia. As frequências cardíaca e respiratória, pressão arterial e temperatura retal foram mensuradas durante todos os momentos de avaliação. Durante a anestesia, foram incluídas as análises da fração expirada de dióxido de carbono, fração expirada de isofluorano e saturação da oxihemoglobina periférica. A hemogasometria foi realizada previamente a raquianestesia a ao término do procedimento cirúrgico. O grau de sedação, foi analisado no período de recuperação com auxílio de escore A raquianestesia com bupivacaína e clonidina não promoveu alterações na frequência e ritmo cardíaco, pressão arterial nem depressão respiratória tendo em vista que os valores de frequência respiratória e fração expirada de dóxido de carbono permaneceram dentro dos valores fisiológicos. O emprego de bupivacaína isolada e em associação à clonidina promoveu redução da concentração expirada de isofluorano (respectivamente 63,5% e 70) quando comparados ao grupo controle. O uso de clonidina determinou sedação no período de recuperação. O uso da raquianestesia com bupivacaína isobárica a 0,5% isolada ou em associação à clonidina demonstrou boa estabilidade hemodinâmica e significativa diminuição no requerimento de anestésico geral; a clonidina potencializou o efeito da bupivacaína isobárica no momento cirúrgico e apresentou grau satisfatório de sedação no período pós operatório / This study compares effects of spinal anesthesia with isobaric bupivacaine at 0,5% either isolated or associated to clonidine administered to female cats undergoing ovariohysterectomy under the effect of propofol and isoflurane. Meperidine was administered to thirty female cats whose anesthetic induction was performed 15 minutes later with the help of propofol followed by isoflurane for maintenance of anesthesia. The female cats were split into three different groups which received one of the following substances each for spinal anesthesia: physiological saline solution (GSF); isobaric bupivacaine (GB); isobaric bupivacaine and clonidine (GBC). All thirty animals underwent ovariohysterectomy. Heart and respiratory rate, blood pressure and rectal temperature were measured throughout the procedures. Under anesthesia, the fraction of expired carbon dioxide, the fraction of expired isoflurane and the saturation of oxihemoglobin were analyzed. Arterial blood gasometry was performed before spinal anesthesia and after surgical procedures. The level of sedation was analyzed during recovery with the help of scores from Selmi et al. (2004) Spinal anesthesia associated to bupivacaine and clonidine did not alter the heart rate, blood pressure or respiratory depression once the respiratory rate numbers and the fraction of expired carbon dioxide numbers ranged within the normal physiological values. The use of bupivacaine, either isolated or associated to clonidine, led to the reduction of the concentration of expired isoflurane (63,5% and 70% respectively) when compared to the control group. The use of clonidine led to sedation during recovery. The use of spinal anesthesia combined with isobaric bupivacaine at 0,5%, isolated or associated to clonidine, demonstrated good hemodynamic stability and a significant decrease in the need of general anesthesia; clonidine optimized the effect of isobaric bupivacaine throughout surgical procedures and also showed a satisfactory level of sedation during the postoperative period

This thesis aims to contribute to the research and development of a new highly efficient split-cycle engine concept – the double compression-expansion engine (DCEE) – by expanding the knowledge of combustion processes suitable for this and, potentially, other modern engines, via experimental and computational studies. In this work, first, the importance of continued improvement of internal combustion engines is demonstrated by comparing the life-cycle CO2 emissions of different modes of transport, including walking and bicycling. Then, an isobaric combustion concept is proposed for use in modern high-pressure combustion engines, such as the DCEE. Isobaric combustion is compared to conventional diesel combustion at different pressure levels, fueling, and EGR rates, and shown to reduce cylinder wall heat transfer losses by 20 %, simultaneously improving the NOx emissions by a factor of two. An in-situ injection rate measurement technique is developed and applied to improve the understanding of the complex injection strategies required for isobaric combustion. It is also shown that isobaric combustion is possible to achieve with a single fuel injector, but using multiple injectors may offer additional benefits of even lower heat losses, better heat release control, and improved soot and NOx trade-off. Then, an alternative combustion system to the diesel isobaric is proposed – a hydrogen direct-injection (DI) compression-ignition (CI) combustion concept, which has the advantage of ideally eliminated CO2 and soot emissions. DICI H2 combustion is found to differ significantly from conventional diesel, most importantly, in terms of the injected and retained momentum, and in-cylinder flow patterns and fuel-air mixing. Thus, a completely different optimization path must be taken for H2 engines, which involves maximizing the free-jet mixing phase of combustion while minimizing the momentum-dominated global mixing phase. This is achieved computationally in this work by adapting the combustion chamber shape to the H2 jets and modifying the injector nozzle, which proved effective. Finally, hydrogen combustion is computationally compared to diesel in the context of the DCEE on the basis of thermodynamic system parameters and detailed energy breakdown, and proved superior. Brake thermal efficiencies in the range of 56 % are demonstrated for the entire DCEE powertrain fueled with hydrogen.

Extensive analysis of the physical and chemical effects controlling the operation of combustion modes driven by auto-ignition is presented in this thesis. Specifically, the study integrates knowledge attained by analyzing the effects of fuel molecular structure on auto-ignition, quantity or quality of charge dilution, and in-cylinder temperature and pressure on burning characteristics in single and multiple injection strategies employed in compression ignition (CI), partially premixed combustion (PPC) and homogenous charge compression ignition (HCCI) engines. In the first section of the thesis, a multiple injection strategy aimed to produce heat at a constant pressure, commonly known as isobaric combustion, has been studied. Then, to eliminate the complexity of spray-to-spray interactions observed with isobaric combustion, the second section of the thesis is focused on compression ignition (CI) through single injection. In the final section, the presentation will move towards moderate conditions with high dilution, in which combustion becomes dominated by chemical kinetics. At these conditions, there is emerging evidence that certain fuels exhibit unusual heat release characteristics where fuel releases heat in three distinctive stages. Overall, the thesis discusses factors controlling the auto-ignition for CI, PPC and HCCI engines that can provide valuable insights to improve their operation. Isobaric combustion in CI engine involves large interactions between physical and chemical effects. Injection of spray jets into oxygen-deprived regions catalyzes the mechanism for soot production – urging to employ either multiple injectors, low reactivity fuel or an additional expansion stage. Fuels – regardless of their auto-ignition tendency – share the same combustion characteristics in the high load CI, where auto-ignition is controlled by only the injector’s physical specifications. Such observation is a showcase of the fuel flexible engines that has the potential of using sustainable fuels – without being restrained by the auto-ignition properties of the fuel. The thesis provides evidence from experiment and simulation that three-stage auto-ignition is indeed a phenomenon driven by chemical kinetics. Three-stage auto-ignition opens the perspective to overcome the limitation of the high-pressure rise rates associated with HCCI engine.

This thesis presents Monte Carlo methods for simulations of phase behaviors of Lennard-Jones fluids. The isobaric-isothermal (NPT) ensemble and Gibbs-NPT ensemble are introduced in detail. NPT ensemble is employed to determine the phase diagram of pure component. The reduced simulation results are verified by comparison with the equation of state by by Johnson et al. and results with L-J parameters of methane agree considerably with the experiment measurements. We adopt the blocking method for variance estimation and error analysis of the simulation results. The relationship between variance and number of Monte Carlo cycles, error propagation and Random Number Generator performance are also investigated. We review the Gibbs-NPT ensemble employed for phase equilibrium of binary mixture. The phase equilibrium is achieved by performing three types of trial move: particle displacement, volume rearrangement and particle transfer. The simulation models and the simulation details are introduced. The simulation results of phase coexistence for methane and ethane are reported with comparison of the experimental data. Good agreement is found for a wide range of pressures. The contribution of this thesis work lies in the study of the error analysis with respect to the Monte Carlo cycles and number of particles in some interesting aspects.

Traditional excess Gibbs energy models in terms of temperature, pressure, and concentration become progressively less effective in describing the thermodynamics of aqueous solutions at temperatures above 300 ¢ªC, and are totally inadequate in the critical region of water. This deficiency is due to the strong ion association and the large property fluctuations (such as density) with small variations in pressure, temperature, and solute concentration around the critical point of water. In this work, a speciation-based model has been developed to describe the thermodynamic properties of aqueous sodium chloride solutions in the critical region of water. The anomalous fluctuation problem is avoided by adopting a residual Helmholtz energy approach in terms of temperature, density, and solute concentration. Partial ion dissociation is accounted for by including an isochoric equilibrium constant equation and a mean spherical approximation in the present model. The present model includes such classical interactions or effects as hard-sphere interactions, dipole-dipole interactions, ion dissociation effects, long-range ion-ion interactions, and a non-classical perturbation term. The related parameters that account for these effects were regressed to fit the measured values in the critical region of water. Densities, compressibility factors, apparent molar volumes, heats of dilution, and apparent isobaric molar heat capacities were used to test the validity of the model. The predicted values in this work agree well with the literature data over a wide range of temperatures (350 to 400 ¢ªC), pressures (17.5 to 40 MPa), and sodium chloride concentrations (0 to 5 mol/kg). Comparisons with other models are also included in this work. This model can be used to predict speciation, solute dissociation reaction, and many other comprehensive properties in aqueous sodium chloride solutions at near-critical conditions.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-05-15T18:35:26Z No. of bitstreams: 1 LEANDRO FONTES DE SOUSA – DISSERTAÇÃO (PPGMET) 2015.pdf: 2595995 bytes, checksum: 9e598a653c739e5ba10d80c7e96c05f3 (MD5) / Made available in DSpace on 2018-05-15T18:35:26Z (GMT). No. of bitstreams: 1 LEANDRO FONTES DE SOUSA – DISSERTAÇÃO (PPGMET) 2015.pdf: 2595995 bytes, checksum: 9e598a653c739e5ba10d80c7e96c05f3 (MD5) Previous issue date: 2015-03-06 / Capes / Neste trabalho as condições atmosféricas na área de Petrolina no mês chuvoso de abril de 2014 são analisadas com foco no evento extremo de chuva do dia 8. A base de dados utilizada é formada por dados de reanálise, imagens realçadas de satélite meteorológico, totais diários e horários de precipitação, valores horários do vento à superfície e sondagens diárias de ar superior. Técnicas de análise meteorológica são empregadas para diagnosticar o ambiente em escala sinótica e mesoescala associado ao evento extremo. Dados em níveis isobáricos padrões e índices de estabilidade são submetidos separadamente a técnicas de análise multivariada para identificar fatores físicos e verificar a adequação dos índices como indicadores de ocorrência de chuva na região semiárida. As chuvas são registradas entre os dias 7 e 12, e no dia 27 de abril, associadas a ventos de sudeste fracos à superfície. O evento extremo de chuva do dia 8 é causado por um sistema convectivo multicelular que se desenvolve em condições de grande escala caracterizada pela Zona de Convergência Intertropical (ZCIT) atuando no extremo norte e ao norte do Nordeste do Brasil, pela alta da Bolívia deslocada para leste de sua posição climatológica, e por um cavado de grande amplitude na alta troposfera, a leste da América do Sul. A aplicação da análise (fatorial) de componentes principais (ACP) permite reduzir um conjunto de nove variáveis em três componentes principais (CPs) que retém acima de 90% da variância total dos dados, em cada nível isobárico analisado. A primeira CP retida explica as variações da temperatura do ar nos níveis de 925 hPa, 850 hPa e 200 hPa, e as variações do teor de umidade no nível de 500 hPa. A aplicação da análise de agrupamentos (AA) aos fatores retidos possibilita identificar seis grupos de dias homogêneos em termos das condições atmosféricas, em cada nível isobárico. A aplicação da ACP aos índices de estabilidade permite reduzir um conjunto de dez índices em três CPs que retém 82,8% da variância total dos dados. A aplicação da AA permite identificar grupos de dias nos quais os índices representam alta ou baixa condição de instabilidade. Os índices CAPE, LI, SI, K, TT e SWEAT são os que melhor representam características termodinâmicas e dinâmicas da atmosfera no mês de estudo, apresentando as maiores variações nos dias que antecedem os eventos de chuva, uma indicação de que podem ser úteis na previsão desses eventos na região semiárida do Nordeste do Brasil. / The present work analyzes the atmospheric conditions found over the area of Petrolina during the rainy month of April, 2014. These conditions have been analyzed focusing on the extreme rainfall event of April 8th. The database used consisted of reanalysis data, enhanced weather satellite images, daily and hourly rainfall totals, wind hourly values taken at the surface and upper air daily soundings. Weather analysis techniques have been used to diagnose the environment at synoptic scale and mesoscale all associated to extreme event. Data based on isobaric standard levels and stability indices have been submitted separately to multivariate analysis techniques in order to identify physical factors and verify the appropriateness of indices such as those of indicative of rain occurrences in the semiarid region. Rainfall was recorded between the 7th and 12th, and also the 27th of April related to weak southeast winds at the surface.The rain extreme event on April 8th was caused by a multicellular convective system which develops along large-scale conditions, characterized by the Inter-tropical Convergence Zone (ITCZ) acting at the far north and north of Northeastern Brazil, the Bolivian high moved east of its climatological position, and a high amplitude trough in the upper troposphere, east of South America. The use of factorial analysis for the principal components (PCA) reduces a set of nine variables along three principal components (PCs) which retain over 90% of the total data variance at all isobaric levels analyzed. The first retained PC accounts for the variations of temperature levels at 925 hPa, 850 hPa and 200 hPa, and also the moisture content variations at 500 hPa level. The application of cluster analysis (CA) to retained factors has helped in the identification of six groups of homogeneous days, considering the atmospheric conditions at each isobaric level. The application of PCA to a set of ten stability indexes results in three retained PCs holding 82.8% of the data total variance. CA application allows us to identify days that belongs to groups on which the indices represent either high or low instability condition. The indices CAPE, LI, SI, K, TT and SWEAT are the ones that best represent the thermodynamic and dynamic features of the atmosphere in the month studied. They have presented the largest variations on the days before rainfall events; an indication that may be useful in forecasting these events in the semiarid region of Northeast Brazil.

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