The microwave resonator technique has been successfully employed in the study of a liquid model of a z pinch. A liquid column has formed an integral part of a microwave cavity, and changes in the frequency of such a cavity have been used to study the growth rates of the current driven instability. The growth rates of the instability are seen to be in agreement with the standard theory for the wavelength equal to three centimeters. It is also seen that a definite stabilization is reached for a finite pinch amplitude. A simple theory balancing compressive streamline forces and magnetic pressure show that the maximum pinched amplitude should grow as the square of the axial current, which is what was observed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Orientador: Maria Regina Wolf Maciel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-07-19T19:58:51Z (GMT). No. of bitstreams: 1 Westphalen_DenisLibert_M.pdf: 3649815 bytes, checksum: cb7d3824a100a56ccbea071f5c27dd07 (MD5) Previous issue date: 1993 / Resumo: Síntese de processos é uma área de pesquisa da engenharia química relativamente recente que se preocupa com a sistematização do projeto conceituaI de processos químicos. Neste trabalho, um fluxograma para fabricação de 2-butanol foi concebido utilizando-se técnicas de síntese de processos. A rota de reação escolhida foi a hidratação de butenos lineares sobre resina de troca iônica fortemente ácida. Seguindo uma hierarquia de decisões, o trabalho foi dividido em três etapas: projeto do reator, sistema de separação e reciclos; e rede de trocadores de calor e utilidades. Na etapa projeto do reator, um projeto simplificado do reator foi elaborado de modo a se identificar suas variáveis de projeto e uma estimativa do custo do equipamento. No estudo do sistema de separação, foi realizada a escolha dos equipamentos de separação apropriados, seu sequenciamento e projeto preliminar. O sistema de separação concebido é composto por três colunas de destilação: Coluna de Separação de Butenos, Coluna de Separação de 2-butanol e Coluna de Separação de di-sec-butil-éter. Para o cálculo do custo da rede de trocadores de calor e do consumo de utilidades, recorreu-se à Tecnologia PINCH, que permite a obtenção destes dados sem o projeto da rede de trocadores. Desta forma, o custo de fabricação do 2-butanol considerando-se os principais equipamentos, foi calculado e chegou-se à conclusão que os valores ótimos das variáveis de projeto: conversão de butenos no reator e concentração de butenos na corrente de purga estão em tomo de 60% e 40%, respectivamente / Abstract: Not informed. / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

This thesis describes the results of two process system engineering studies: (1) hydrogen pinch analysis; and (2) application of COSMO-SAC (conductor-like screening model – segment activity coefficient) to electrolytes. Part (1) presents an automated spreadsheet method that can quickly help minimize fresh hydrogen consumption and maximize hydrogen recovery and reuse in petroleum refineries and petrochemical complexes. Part (1) has appeared as a featured article on engineering practice in the Chemical Engineering Magazine, volume 115, pp. 56-61, June 2008. We present an automated spreadsheet on our research group website (www.design.che.vt.edu) and describe procedures for using the spreadsheet in this thesis. Part (2) discusses the application of the conductor-like screening model – segment activity coefficient (COSMO-SAC), a liquid-phase activity-coefficient model, to electrolytes. We offer detailed procedure for obtaining sigma profiles for electrolytes. A sigma profile is a molecular-specific probability distribution of the surface-charge density, which enables the application of solvation-thermodynamic models to predict vapor-liquid and solid-liquid equilibria, and other properties. We propose to add an additional term to the exchange energy to account for ion-ion attractive and repulsive forces. We also look at the resulting exchange energy behavior. Although accurate numerical results are not achieved, we are able to produce results that match literature data by adding an adjustment factor. / Master of Science

No description available.

Evolution of measured profiles of densities, temperatures and velocities in the edge pedestal region between successive ELM (edge-localized mode) events are analyzed and interpreted in terms of the constraints imposed by particle, momentum and energy balance in order to gain insights regarding the underlying evolution of transport processes in the edge pedestal between ELMs in a series of DIII-D discharges. The data from successive inter-ELM periods during an otherwise steady-state phase of the discharges were combined into a composite inter-ELM period for the purpose of increasing the number of data points in the analysis. These composite periods were partitioned into sequential intervals to examine inter-ELM transport evolution. The GTEDGE integrated modeling code was used to calculate and interpret plasma transport and properties during each interval using particle, momentum, and energy balance. Variation of diffusive and non-diffusive (pinch) particle, momentum, and energy transport over the inter-ELM period are examined for discharges with plasma currents from 0.5 to 1.5 MA and inter-ELM periods from 50 to 220 ms. Diffusive transport is dominant for ρ< 0.925, while non-diffusive and diffusive transport are very large and nearly balancing in the sharp gradient region 0.925 <ρ <1.0. Transport effects of ion orbit loss are significant for ρ > 0.95, and are taken into account. During the inter-ELM period, diffusive transport increases slightly more than non-diffusive transport, increasing total outward transport. Both diffusive and non-diffusive transport have a strong inverse correlation with plasma current. Weakening the electromagnetic pinch may increase outward particle transport, and enable control over the rebuilding of the edge pedestal between ELMs.

Made available in DSpace on 2016-06-02T19:56:53Z (GMT). No. of bitstreams: 1 5833.pdf: 3594761 bytes, checksum: 22ca28a1942a7b8b691c4f52f98f2924 (MD5) Previous issue date: 2014-02-17 / Universidade Federal de Sao Carlos / The increase in demand for biofuels has driven the development of new technologies such as ethanol production from sugarcane bagasse hydrolysis. Given the importance of Brazil in the ethanol market, the inclusion of technology of second generation ethanol will intensify its production. Energy integration in a sugarcane biorefinery provides important advantages for industrial processes such as better energy management, environmental benefits and increased ethanol production. The last factor is due to lower steam consumption in plant with energy integration, so, less bagasse is needed for cogeneration and a fraction of the surplus can be made available for production of second generation ethanol. In this context, the present study conducted energy integration of a sugarcane biorefinery in order to reduce the consumption of utilities. The technique used was Pinch analysis, an established methodology in the area of energy integration. The biorefinery used in this work consists of process for first and second generation ethanol and electricity production simulated in EMSO software (Environment for Modeling, Simulation, and Optimization). Six different scenarios of biorefinery were evaluated, which differ by pretreatment for bagasse (hydrothermal, diluted acid and steam explosion) and by inclusion or not of pentoses fermentation step. Processes that consider pentoses fermentation step have higher ethanol production when compared to processes that do not make use of pentoses fraction, but steam consumption increases in the same order of magnitude of ethanol production. For the six scenarios evaluated energy integration demonstrated a reduction in energy consumption over 50% when compared to corresponding processes without energy integration and over 30% when compared to process with project integration, as commonly found in Brazilian plants. Besides the economic advantage due to decreased costs of hot and cold utilities, the energy integration provides better energy management, reduction in emission of gases and liquid effluents and increases the availability of bagasse for production of second generation ethanol and/or electricity. / O aumento na demanda por biocombustíveis tem impulsionado o desenvolvimento de novas tecnologias como a produção de etanol a partir da hidrólise do bagaço de cana-de-açúcar. Dada a grande importância do Brasil no mercado de etanol, a inserção da tecnologia de etanol de segunda geração potencializará o crescimento da produção. A integração energética em uma biorrefinaria de cana-de-açúcar proporciona importantes vantagens ao processo industrial como a melhor gestão de energia, benefícios ambientais e aumento na produção de etanol. O último fator se deve ao menor consumo de vapor na planta com a integração energética, logo, menos bagaço é necessário para o sistema de cogeração e parte do excedente pode ser disponibilizado para a produção de etanol de segunda geração. Neste contexto, o presente estudo realizou a integração energética de uma biorrefinaria de cana-de-açúcar com o objetivo de reduzir o consumo de utilidades. A técnica utilizada foi a análise Pinch, metodologia consagrada na área de integração energética. A biorrefinaria empregada neste trabalho consiste do processo de produção de etanol de primeira e segunda geração e energia elétrica por simulação computacional realizada no software EMSO (Environment for Modeling, Simulation, and Optimization). Foram avaliados seis cenários diferentes da biorrefinaria, os quais diferem pelo tipo de pré-tratamento para o bagaço (hidrotérmico, ácido diluído e explosão a vapor) e pela consideração ou não da etapa de fermentação das pentoses. Os processos com os pré-tratamentos hidrotérmico, ácido diluído e explosão a vapor com a inclusão da etapa de fermentação das pentoses tem maior produção de etanol quando comparado aos processos que não fazem uso da fração de pentoses, porém o consumo de vapor aumenta na mesma ordem de grandeza da produção de etanol. Para os seis cenários avaliados a aplicação da integração energética demonstrou uma redução no consumo de energia acima de 50% se comparada aos correspondentes processos sem integração energética e acima de 30% se comparada aos processos com integração de projeto, como comumente encontrados nas usinas brasileiras. Além da vantagem econômica, devido à diminuição nos custos de utilidades quentes e frias, a integração energética do processo proporciona melhor gestão de energia, redução na emissão de gases e efluentes líquidos e aumenta a disponibilidade de bagaço para a produção de etanol de segunda geração e/ou energia elétrica.

<p>Funding Agency:</p><p>Health Research Council in the South-East of Sweden</p>

No description available.

ABSTRACT One of the most important tasks in the chemical industry is the separation of multicomponent liquid mixtures into one or more high-purity products. Several technologies are feasible for this task, either alone or in combination, such as distillation, extraction, crystallization, ect. Among these, distillation is by far the most widely spread and has a long history in chemical technology. However, until recently, there has been no systematic approach for understanding the separation of complex mixtures where azeotropes and multiple liquid phases may occur. There has been a growing interest in the use of residue curve and column profiles for the preliminary design of distillation columns. Residue curves and column profile are not only used to predict the composition changes in the distillation column but also to determine the feasibility of the proposed separation. Recently, theory underlying column profile maps has been developed by Tapp, Holland and co-workers. However there has been no direct experimental validation of the predictions of the column profile map theory. The main aim of this thesis is to experimentally verify some of the predictions of column profile map theory. A simple experimental batch apparatus has been developed to measure residue curve maps (RCMs) by Tapp and co-workers, the apparatus was modified so that it could be used to measure column profile maps (CPMs) in this thesis. CPM theory has shown that CPMs are linear transforms of the residues curve maps (RCMs). A stable node which was the apex of a mass balance triangle (MBT) was introduced inside the MBT, this was done by transforming the RCMs to CPMs using the appropriate distillate composition xd and reflux ratio R. It was also shown that the saddle point which was on the boundary of the triangle of the RCM can be shifted inside the MBT by transforming the RCM to CPM. This is again in accordance with theoretical predictions of CPM theory. iv Residue curves (RCs) and pinch point curves (PPCs) are used to determine the operation leaves and hence the feasible region for distillation columns operating at a specific distillate and bottoms composition for all fixed reflux ratio. The operating leaves were expanded beyond the pinch point curve by varying the reflux ratio from a higher reflux to a lower reflux ratio. This showed that one can effectively cross the pinch point curve hence expanding the operating leave. Finally the importance of experimentally measuring CPMs is demonstrated. Two thermodynamic models were used to predict the profiles of a complex system. The binary vapor-liquid equilibrium (VLE) diagrams and the residue curves produced from using these two thermodynamic models did not predict the same topology. The composition of the profiles were not the same because there were multiple liquid phases involved in this system, which made it difficult for the researchers to measure the correct profiles. Column profile maps were simulated using the different thermodynamic models, they also showed that there is some discrepancy between the predictions of the two models.

This thesis sought to: 1) examine the effect of a number of organism and task constraints on the control of two forms of physiological tremor, namely postural and finger-pinch force tremor; and 2) determine if the expected constraint-related changes in tremor output were associated with alterations in the control strategy utilised by the performer. The organism constraints were age and resistance-training (for both forms of tremor), while the task constraints were visual feedback, target size and limb preference (postural tremor) and mean force, target shape and limb preference (force tremor). The postural (index finger) tremor amplitude of young adults was significantly greater in the augmented vision (AV) than normal vision (NV) conditions and when using the non-preferred than preferred limb. Even greater differences/changes in postural tremor amplitude were observed as a function of aging and training. Older adults had significantly more index finger tremor amplitude than young adults. Regardless, the older adults who completed a six weeks program of unilateral strength- or coordination-training were able to significantly reduce their tremor amplitude. Although the training-related reductions in tremor amplitude were of a greater magnitude for the trained than untrained limb, a significant reduction in the tremor amplitude of the untrained limb was also observed for the coordination-training group. All of these significant differences/changes in tremor amplitude were associated with significant changes in a number of other dependent variables. For example, the task- and age-related increases in tremor amplitude were primarily a result of greater 8-12 Hz tremor power and were associated with increased EMG activity/co-activation of the extensor digitorum (ED) and flexor digitorum superficialis (FDS) muscles and a significant reduction in intra-limb (index finger-hand and forearm-upper arm) coupling. The significant reductions in tremor amplitude observed for the resistance-trained older adults was a result of a significant decline in 8-12 Hz power and were associated with a significant reduction in ED and FDS co-activation. However, no significant change in intra-limb coupling was observed. The overall trends observed in the results for the finger-pinch force tremor experiments were similar to those for postural tremor. Older adults had significantly more finger-pinch force tremor (i.e. force variability and targeting error) than young adults, although older adults who performed six weeks of unilateral strength-training were able to significantly reduce the force variability and targeting error of the trained limb. No significant training-related reduction in force tremor was however observed for the untrained limb. The significant age-related increase in force tremor was a result of greater low frequency (less than 2 Hz) power and was associated with a significant loss of inter-digit force sharing and coupling as well as tactile sensitivity. Interestingly, the training-related decreases in force tremor were not associated with significant changes in any of the frequency, sharing or coupling measures. Collectively, the results of the five experiments contained in this thesis add much to our understanding of postural and force tremor. Results indicated that numerous task and organism constraints can have a substantial effect on the resulting tremor output. Furthermore, the task- and age-related differences in the power spectral, muscle activity and coupling measures suggested that the changes in tremor output were the result of the use of an altered (sub-optimal) control strategy. The age-related increase in postural and force tremor amplitude may therefore reflect not only an overall decline in neuromuscular system function, but also the relative inability of older adults to effectively coordinate the output of numerous degrees of freedom (limb segments). The effect of the aging process on tremor output was somewhat reversible, with the older adults who performed resistance-training significantly improving their control of both postural and force tremor. There was some evidence that resistance-training could produce cross-education effects in older adults, although these were only statistically significant for postural tremor amplitude in the coordination-training group and for wrist flexion strength in the strength-training group. The relative brevity of the training program (6 weeks) and the observable cross-education effects suggest that the reduction in tremor amplitude and increases in strength were primarily a result of neural adaptations. Such findings further support the prescription of resistance-training for improving physical function in older individuals.