Práce se zabývá studiem procesů probíhajících při zhášení silnoproudého oblouku ve zhášecí komoře jističe. Je zaměřena na výpočet dynamiky tekutin a teplotního pole v okolí elektrického oblouku. V práci je dále popsán vliv vzdálenosti plechů v komoře a vliv tvarů plechů z hlediska aerodynamických podmínek uvnitř komory. Dalším cílem dosaženým touto prací je poskytnutí informací o vlivu polohy elektrického oblouku na termodynamické vlastnosti uvnitř komory. Toto je důležité, zejména pokud je oblouk do komory vtahován jinými silami, např. elektromagnetickými a během tohoto vtahovacího procesu mění svůj tvar i polohu. Za účelem co nejjednoduššího, ale zároveň co nejefektivnějšího řešení úkolu, byl vyvinut software určen speciálně pro výpočet dynamiky tekutin numerickou metodou konečných objemů (FVM). Tato metoda je, v porovnání s rozšířenější metodou konečných prvků (FEM), vhodnější pro výpočet dynamiky tekutin (CFD) zejména proto, že režie na výpočet jedné iterace jsou menší v porovnání s ostatními numerickými metodami. Další výhodou tohoto softwarového řešení je jeho modularita a rozšiřitelnost. Cely koncept softwaru je postaven na tzv. zásuvných modulech. Díky tomuto řešení můžeme využít výpočtové jádro pro další numerické analýzy, např. strukturální, elektromagnetickou apod. Jediná potřeba pro úspěšné používání těchto analýz je napsáni solveru pro konečné prvky (FEM). Jelikož je software koncipován jako multi–thread aplikace, využívá výkon současných vícejádrových procesorů naplno. Tato vlastnost se ještě více projeví, pokud se výpočet přesune z CPU na GPU. Jelikož současné grafické karty vyšších tříd mají několik desítek až stovek výpočetních jader a pracují s mnohem rychlejšími pamětmi, než CPU, je výpočetní výkon několikanásobně vyšší.

The current research investigates the use of solid-embedded thermocouples for determining accurate transient temperature measurements within a solid medium, with emphasis on measurements intended for use in inverse heat conduction problems. Metal casting experiments have been conducted to collect internal mold temperatures to be used, through inverse conduction methods, to estimate the heat exchange between a casting and mold. Inverse conduction methods require accurate temperature measurements for valid boundary estimates. Therefore, various sources of thermocouple measurement uncertainty are examined and some suggestions for uncertainty reduction are presented. Thermocouple installation induced bias uncertainties in experimental temperature data are dynamically corrected through the development and implementation of an embedded thermocouple correction (ETC) transfer function. Comparisons of experimental data to dynamically adjusted data, as well as the inverse conduction estimates for heat flux from each data set, are presented and discussed.

No description available.

A modificação das condições iniciais do clima é conseqüência inerente da substituição da cobertura natural do solo pelo ambiente construído. Nesse processo, um dos mecanismos do sistema cidade-atmosfera mais afetado pela mudança do uso e da cobertura do solo é o campo térmico urbano. Assim, esta pesquisa objetivou estudar a configuração do campo térmico da cidade de São Carlos nas suas dimensões espaços-temporais, com vistas a conhecer a intensidade da ilha de calor urbano no período de verão, dentro de suas variações diurnas e das condições impostas pelos diferentes tipos de tempo habituais, com o aporte da abordagem dinâmica do clima. A análise da intensidade do campo térmico urbano foi feita a partir de registros de dados climáticos contínuos tomados em superfície por quatro estações automáticas instaladas em diferentes regiões da malha urbana. Os resultados obtidos denotaram que a maior intensidade da ilha de calor urbano, no período de verão, ocorreu na atuação da massa Tropical Atlântica sobre a região, cujo tipo de tempo habitual foi caracterizado por cenário atmosférico com predominância de céu claro, alta incidência de radiação solar direta e valores de temperatura do ar elevados com máxima diária acima da média das máximas indicadas pelas normais climatológicas. Sob essas condições, observou-se que as características do entorno construído exerceram maior influência no comportamento térmico urbano, na qual as diferenças térmicas entre diferentes regiões dentro da malha urbana de São Carlos foram superiores a \'5 GRAUS\' Celsius. Observou-se, ainda, que a maior expressão da ilha de calor urbano ocorreu após o pôr-do-sol, nos horários entre 21:30h e 22:00h. / The initial conditions of the climate are consequence of replacing the natural ground cover by the built environment. In this process, one of the most affected mechanics of the city-atmosphere system due to the change of use and land cover is the urban thermal field. Thus, this research aim to study the configuration of the thermal field of São Carlos in the spatial and temporal dimensions for understanding the intensity of urban heat island in the summer, taking into account its diurnal temperature variations and imposed conditions by different weather types, guided by the climate dynamics approach. The analysis of the intensity of urban thermal field is made from records of climatic data observed in solid ground for four automatic weather stations placed in different areas of the city. The obtained results denote that the highest intensity of urban heat island in summer occurs in the activity of Tropical Atlantic air mass over the region, where the habitual weather was clear skies with high incidence of direct solar radiation and values of air temperature with high daily maximum above the average of the levels indicated by the climate normals. Under these weather conditions, it is observed that the characteristics of the built environment have a greater influence on urban thermal behavior, in which the temperature variations between different regions within the urban area of San Carlos were above 5 Celsius \'DEGREES\'. It is also observed that the highest intensity of urban heat island occurred after sunset, at times between 21:30 and 22:00h.

In order to understand some of the superconducting mechanisms involving external electric fields at nanometric scales, a Lorentz-covariant extension of the phenomenological Ginzburg-Landau theory has been developed by analogy with the Higgs model of particle physics. Among the specific properties of this model, it has been shown that the phase diagram of some particular geometry submitted to crossed electric and magnetic fields in a stationary situation provides a criterion involving the applied electric field, which could discriminate between the usual Ginzburg-Landau theory and its covariant extension. A sub-microscopic device has been manufactured using microelectronics lithography techniques and was used to perform transport measurements at very low temperatures. However, the experimental measurements of the phase diagram do not reproduce the expectations based whether on the usual or the extended model, suggesting a screening of the electric field by some mechanism which is not accounted for by these phenomenological approaches. A microscopic approach has therefore been developed to extend the s-wave channel of the BCS theory in a relativistic framework, using the functional integral formalism of Finite Temperature Field Theory. In particular, the effective action related to the Ginzburg-Landau free energy was obtained up to second order in the fluctuations of the electromagnetic field and of the superconducting condensate density. This allowed for the identification of the electric and magnetic penetration lengths, inclusive of their dependences on temperature and the chemical potential, which fully explain the experimental results. Several analytic expressions have also been provided for the effective potential in the full range of temperatures between 0 K and the critical temperature, among which the Ginzburg-Landau potential was shown to reproduce this effective potential within the limited range of temperatures where it is expected to be valid.

Submitted by EDUINO RODRIGUES DA COSTA null (eduinocosta@gmail.com) on 2016-01-24T23:10:07Z No. of bitstreams: 1 tese_doutorado_versão_final_2016_4.pdf: 23957151 bytes, checksum: 7698593346da53efae4b6d352ff36ff2 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-01-25T16:07:41Z (GMT) No. of bitstreams: 1 costa_er_dr_prud.pdf: 23957151 bytes, checksum: 7698593346da53efae4b6d352ff36ff2 (MD5) / Made available in DSpace on 2016-01-25T16:07:41Z (GMT). No. of bitstreams: 1 costa_er_dr_prud.pdf: 23957151 bytes, checksum: 7698593346da53efae4b6d352ff36ff2 (MD5) Previous issue date: 2015-12-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho teve como objetivo estudar o campo térmico e a qualidade ambiental urbana de Chapecó, cidade de porte médio localizada na região do Oeste Catarinense. Para estudar o campo térmico de Chapecó ao nível do dossel urbano, foi necessário estabelecer trajetos (transectos móveis) nos quais em condições de tempo especificas de cada mês do ano de 2014, e horários (06, 15 e 21 horas) foram realizadas coletas de dados climáticos (temperatura do ar), afim de identificar e espacializar a ocorrência de fenômenos climáticos urbanos como as ilhas de calor. Para a aquisição dos dados de temperatura do ar na zona urbana de Chapecó, utilizou-se a metodologia dos transectos móveis, a qual consiste na aquisição automática e simultânea de dados climáticos ao longo de trajetos preestabelecidos dentro de determinada malha urbana. Para avaliar e mapear a qualidade ambiental da zona urbana de Chapecó/SC foi utilizado uma adaptação da metodologia desenvolvida por Nucci (1996) ao estudar a qualidade ambiental e o adensamento urbano no distrito de Santa Cecília, localizado no município de São Paulo. Como resultados destaca-se que a ilha de calor atmosférica se definiu melhor no bairro Centro (horizontalizado e verticalizado) no horário das 15 e 21 horas em todos os episódios de tempo analisados. No horário das 06 horas não foi possível notar a influência da cidade sobre o campo térmico, visto que neste horário ocorre o resfriamento radiativo associado ao balanço negativo de radiação. A ilha de calor apresentou maior magnitude na estação de inverno e em episódios de tempo sob domínio de sistemas atmosféricos polares (Massa Polar Atlântica, Massa Polar Continental). Pelo tamanho da cidade e intensidade das alterações ambientais promovidas pela ação antrópica não foi registrada ilhas de calor de fraca magnitude. Em relação ao conforto térmico humano registrado em Chapecó, notou-se que a ilha de calor é responsável pelo desconforto térmico verificado nos tipos de tempos associados a sistemas atmosféricos tropicais no verão e pelo conforto térmico nos episódios de tempo associados a sistemas polares no inverno, principalmente no seu horário de máxima intensidade e aquecimento (15 horas). Em relação a qualidade ambiental, verificou-se que as áreas de baixa qualidade corresponderam as áreas centrais da cidade onde foram identificados e mapeados atributos negativos que reduzem a qualidade do ambiente. As ilhas de calor de média, forte e muito forte magnitude se estabeleceram justamente nas áreas centrais da cidade onde a qualidade ambiental é baixa. Conclui-se que a cidade de Chapecó por seu porte médio e dinâmicas espaciais da sua urbe, tem a capacidade de gerar um clima local; e as alterações ambientais nela verificadas contribuem para reduzir a qualidade do ambiente favorecendo assim o surgimento das ilhas de calor e o desconforto térmico. / This work aimed to study the thermal field and urban environmental quality of Chapecó, medium-sized city located in the western region of Santa Catarina. To study the thermal field of Chapecó in urban canopy level had to be established paths (mobile transects) where in specific weather conditions of each month of the year 2014, and times (06, 15 and 21 hours) samples were taken from climate data (air temperature) in order to identify and spatialize the occurrence of climatic phenomena such as urban heat islands. To acquire the air temperature data in the urban area of Chapecó, we used the methodology of mobile transects, which is the automatic and simultaneous acquisition of climate data along predetermined paths within a given urban area. To assess and map the environmental quality of the urban area of Chapecó / SC was used a methodology developed by adapting Nucci (1996) to study the environmental quality and the urban density in the Santa Cecilia district, located in São Paulo. As a result, it is emphasized that the atmospheric heat island defined better in the Centro neighborhood (horizontalized and vertical) in the time of 15 and 21 hours in all episodes rabbits. On time of 06 hours, it was not possible to note the influence of the city on the thermal field, since this time is the radiative cooling associated with the negative balance of radiation. The heat island showed greater magnitude in the winter season and episodes of time under the control of polar weather systems (Polar Atlantic Mass, Polar Continental Mass). The size of the city and intensity of environmental changes brought about by human action was not recorded weak magnitude of heat islands. Regarding the human thermal comfort registered in Chapecó, it noted that the heat island is responsible for the observed thermal discomfort in the types of associated time tropical weather systems in the summer and the thermal comfort in episodes of time associated with polar systems in the winter, especially in its maximum intensity and heating time ( 15 hours). For environmental quality, it was found that low-quality areas corresponded central city areas, which have been identified and mapped negative attributes that reduce the quality of the environment. The average heat islands, strong and very strong magnitude is precisely established in inner-city areas where environmental quality is low. We conclude that the city of Chapecó for its midsize and space of a dynamic metropolis, has the ability to generate a local climate; and environmental changes occurring in it contribute to reducing the quality of the environment favoring the emergence of heat islands and thermal discomfort. / FAPESP: 2012/01631-1

A modificação das condições iniciais do clima é conseqüência inerente da substituição da cobertura natural do solo pelo ambiente construído. Nesse processo, um dos mecanismos do sistema cidade-atmosfera mais afetado pela mudança do uso e da cobertura do solo é o campo térmico urbano. Assim, esta pesquisa objetivou estudar a configuração do campo térmico da cidade de São Carlos nas suas dimensões espaços-temporais, com vistas a conhecer a intensidade da ilha de calor urbano no período de verão, dentro de suas variações diurnas e das condições impostas pelos diferentes tipos de tempo habituais, com o aporte da abordagem dinâmica do clima. A análise da intensidade do campo térmico urbano foi feita a partir de registros de dados climáticos contínuos tomados em superfície por quatro estações automáticas instaladas em diferentes regiões da malha urbana. Os resultados obtidos denotaram que a maior intensidade da ilha de calor urbano, no período de verão, ocorreu na atuação da massa Tropical Atlântica sobre a região, cujo tipo de tempo habitual foi caracterizado por cenário atmosférico com predominância de céu claro, alta incidência de radiação solar direta e valores de temperatura do ar elevados com máxima diária acima da média das máximas indicadas pelas normais climatológicas. Sob essas condições, observou-se que as características do entorno construído exerceram maior influência no comportamento térmico urbano, na qual as diferenças térmicas entre diferentes regiões dentro da malha urbana de São Carlos foram superiores a \'5 GRAUS\' Celsius. Observou-se, ainda, que a maior expressão da ilha de calor urbano ocorreu após o pôr-do-sol, nos horários entre 21:30h e 22:00h. / The initial conditions of the climate are consequence of replacing the natural ground cover by the built environment. In this process, one of the most affected mechanics of the city-atmosphere system due to the change of use and land cover is the urban thermal field. Thus, this research aim to study the configuration of the thermal field of São Carlos in the spatial and temporal dimensions for understanding the intensity of urban heat island in the summer, taking into account its diurnal temperature variations and imposed conditions by different weather types, guided by the climate dynamics approach. The analysis of the intensity of urban thermal field is made from records of climatic data observed in solid ground for four automatic weather stations placed in different areas of the city. The obtained results denote that the highest intensity of urban heat island in summer occurs in the activity of Tropical Atlantic air mass over the region, where the habitual weather was clear skies with high incidence of direct solar radiation and values of air temperature with high daily maximum above the average of the levels indicated by the climate normals. Under these weather conditions, it is observed that the characteristics of the built environment have a greater influence on urban thermal behavior, in which the temperature variations between different regions within the urban area of San Carlos were above 5 Celsius \'DEGREES\'. It is also observed that the highest intensity of urban heat island occurred after sunset, at times between 21:30 and 22:00h.

Fouling of tube bundles in boilers on the flue gas side affects not only the service life, but also the boiler heat output and increases maintenance and operating costs. Therefore, it is necessary to minimize or completely eliminate this process. This thesis focuses on comparison of the service life and the heat output of the tube bundles with and without deposit in the coal fired boiler. Simulations of flue gas flow in area of tube bundles with and without deposit are performed using ANSYS Fluent software, which shows that the surface of tube bundles with deposit is much less heated than the surface without deposit. The thermal loads of tubes obtained by the CFD analysis are applied to the model, which is created in the program ANSYS Mechanical, where the calculation of the temperature field in the cross section of the pipe is realized. The effect of fouling on creep life and heat output is then evaluated based on simulation results. The results show that fouling increases creep life, but significantly reduces heat output of heavily fouled tubes. Hence the flue gas flows at a higher temperature to the rest of the tube bundle, and the service life of those tubes will therefore probably decrease.

This study performed detailed measurements on and around scaled up conducting and adiabatic airfoils with and without film cooling. The conducting vane was a matched Bi airfoil, which accurately scaled the convective heat transfer and conduction through the solid, in order to produce non-dimensional surface temperatures and thermal boundary layers that were representative of an actual engine. Measurements made on all vane models included surface temperature measurements and thermal profiles above the walls. Separate measurements on non-film cooled and film cooled conducting models allowed for the individual contributions of the internal convective cooling and external film cooling to the overall cooling scheme to be quantified. Surface temperature and thermal field measurements above the wall were also performed on a film cooled adiabatic model. For the conducting model with internal cooling only, strong streamwise temperature variations were seen. The surface temperature variations were highly dependent on the local external and internal heat transfer coefficients. Spanwise temperature variations also existed, but were modest in comparison to streamwise variations. Comparing the thermal fields above the film cooled adiabatic and conducting walls allowed for the assumption that the conducting wall would not significantly affect the thermal field in the film cooling jet to be tested. Near the edge of the film cooling jet the developing thermal boundary layer had a clear effect on the overlying gas temperature, suggesting that the common assumption that the adiabatic wall temperature is the appropriate driving temperature for heat transfer to a film cooled wall was invalid. On the jet centerline thermal boundary layer effects were less influential, due to the development of a new, thin boundary layer. This suggested that the adiabatic wall temperature as driving temperature for heat transfer was a reasonable assumption on the jet centerline for most cases tested. As film cooling momentum flux ratio increase, thermal boundary layer effects became more influential on the jet centerline. Additionally, the high resolution surface temperature measurements and thermal field measurements above the wall presented in the current study represent a significant improvement in the data available for validation of computational simulations of conducting turbine airfoils. / text

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Neste trabalho, utilizamos o formalismo de teorias quânticas de campos a temperatura finita, tal como desenvolvidas por Matsubara, aplicado a uma hamiltoniana de N campos escalares com autointeração quártica a N grande. Obtém-se uma expressão, na primeira aproximação quântica, para o coeficiente do termo quadrático da hamiltoniana ("massa quadrada"), renormalizado, como função da temperatura. A partir dela, estudamos o processo de quebra espontânea de simetria. Por outro lado, a mesma hamiltoniana é conhecida como modelo de Ginzburg-Landau na literatura de matéria condensada, e que permite o estudo de transições de fase em materiais ferromagnéticos. A temperatura é introduzida através do termo quadrático na hamiltoniana, de forma linear: é proporcional à diferença entre a variável de temperatura e a temperatura crítica. Tal modelo, porém, possui validade apenas na regi~ao de temperaturas próximas à criticalidade. Como resultado de nossos cálculos na teoria de campos a temperatura finita, observamos que, numa faixa de valores em torno da temperatura crítica, a massa quadrática pode ser aproximada por uma relação linear em relação à variável de temperatura. Isso evidencia a compatibilidade da abordagem de Ginzburg-Landau, na vizinhança da criticalidade, com respeito ao formalismo de campos a temperatura finita. Discutimos também os efeitos causados pela presença de um potencial químico no sistema. / In this work, we use the formalism of quantum field theories at finite temperature, as developed by Matsubara, applied to a Hamiltonian of N scalar fields with quartic self-interaction at N large. We get an expression in the first quantum approximation to the coeficient of the quadratic term of the Hamiltonian ("square mass"), renormalized as a function of temperature. From it, we study the process of spontaneous symmetry breaking. On the other hand, the same Hamiltonian is known as Ginzburg-Landau model in the literature of condensed matter, and allows the study of phase transitions in ferromagnetic materials. The temperature is introduced through the quadratic term in the Hamiltonian of the linear form: is proportional to the difference between the temperature and the critical temperature. This model, however, is valid only in the region of temperatures close to criticality. As a result of our calculations in the field theory at finite temperature, we observed that in a range of values around the critical temperature, the quadratic mass can be approximated by a linear relation with the temperature. This highlights the compatibility of the Ginzburg-Landau approach, in the vicinity of criticality with respect to the formalism of finite temperature field. We also discuss the effects caused by the presence of a chemical potential in the system.