Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains v, 46 p. : col. ill. Includes abstract. Includes bibliographical references.

A room temperature water model of a tundish was design, constructed and operated. The model was equipped with a steam heating system that simulates that simulates the tundish plasma heating systems operated by some of the more modem continuous casting plants. Similarity between steam heating in the water model and plasma heating in the tundish has been established. A dimensionless criterion was developed to validate the simulation experiments and its represented by the plasma heating number. Using this similarity criterion plasma heating can be simulated by steam heating in an appropriately designed water model. A theoretical dispersion model has been formulated for the flow through the tundish and the parameters in this model determined from the results obtained from residence time distribution measurements. A conductivity method was used, a highly conducting species being injected at the inlet point and changes in conductivity monitored at the exit. Measurements were also made of the changes in temperature at the exit resulting both from changes in temperature of the inlet stream and from the use of steam heater system. A stable inverse heat conduction method has been developed in which the measured and estimated temperature are analysed in terms of a steady components of short duration. A finite difference method has been used to predict the effect on a thermocouple temperature of the deviatory components of the liquid steel temperature. The incorporation of these predictions into look-up tables has allowed an algorithm to be developed thet can deduce the current deviatory component of the steel temperature from the thermocouple response.

Orientador: Giselle Maria Marchi Baron / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-18T10:15:57Z (GMT). No. of bitstreams: 1 Araujo_LarissaSgarbosaNapoleaode_M.pdf: 3474527 bytes, checksum: 9bfdeda78eb0f2e753e727642f5d8c80 (MD5) Previous issue date: 2011 / Resumo: O objetivo deste estudo foi avaliar a influência de diferentes tempos (5s, 10s, 20s) e temperaturas (±23º, ±40ºC) para volatilização de sistemas adesivos [Excite (EX) e Single Bond 2 (SB)] sobre o grau de conversão (GC), resistência coesiva (RC), módulo de elasticidade (ME) e resistência à flexão (RF). A fonte de luz LED - Elipar Free Light 2 foi utilizada para fotoativação das amostras por 20 s (1100 mw/ cm2). Para a análise da RC, RF e ME cada corpo de prova foi confeccionado a partir de uma matriz de silicone por adição em forma de barra (2x1x7mm). Sobre a matriz, foram dispensados 10 ?L de adesivo após receberem leve jato de ar com tempo e temperatura variando de acordo com cada grupo, e fotoativados por 20s. Para análise de RC (n=10), os corpos de prova foram fixados à Máquina de Ensaio com célula de carga de 200N, e para RF e ME (n=5) com carga de 50N, ambos realizados a 0,5mm/ min, até a ruptura da amostra. Para mensuração do GC (n=5) foram dispensados 3?L de adesivo sobre o cristal e utilizada espectroscopia de transmissão infravermelha de Fourier (FTIR) na faixa de 1665 a 1580 cm-1. Os dados foram submetidos a análise de variância 3 fatores e teste de Tukey (p< 0,05). Para EX e SB, a temperatura de ±40ºC resultou em maior RC em todos os tempos de volatilização. Os maiores valores de RC foram observados no tempo de 20s, seguidos dos tempos de 10s e 5s, respectivamente. Maiores valores de RC foram encontrados para o adesivo EX comparativamente ao SB. Para GC não houve diferença estatisticamente significante para EX entre as temperaturas e tempos de volatilização estudados. Para SB, maiores valores de GC foram obtidos com a temperatura de ±40ºC com exceção do grupo volatilizado por 20s, que não diferiu estatisticamente da temperatura de ±23ºC. EX apresentou maiores valores de GC que SB, independente de tempo e temperatura de volatilização. Com relação ao ME, para EX não houve diferença estatisticamente significante entre os tempos e as temperaturas de volatilização. Apenas para SB, a temperatura de ±40ºC promoveu aumento no ME e, entre os tempos de volatilização não houve diferença estatisticamente significante. De acordo com o resultado da análise da RF, para EX não foi observado efeito estatisticamente significante entre as temperaturas de volatilização estudadas. A volatilização à temperatura de ±40ºC de SB resultou em melhor desempenho na RF. Para tempo de volatilização, tanto para SB quanto para EX, independente da temperatura de volatilização, os tempos de 20 e 10s não diferiram estatisticamente entre si e foram maiores do que 5s. Os resultados deste estudo indicam que há uma superioridade do adesivo à base de etanol sobre os que associam etanol e água. De modo geral, a volatilização por 20s elevou o desempenho dos sistemas adesivos testados. A volatilização com altas temperaturas dos sistemas adesivos avaliados, elevou o GC bem como as propriedades mecânicas dos mesmos. O ar aquecido elevou a resistência coesiva dos adesivos à base de etanol / Abstract: The aim of this study was to evaluate the influence of different times (5s, 10s, 20s) and temperatures (±23º, ±40ºC) for volatilization of various adhesive systems [Excite (EX) and Single Bond 2 (SB)] on the degree of conversion (DC), cohesive strength (CS), modulus of elasticity (ME) and the flexural strenght (FS). The light curing unit Elipar Free Light 2- LED was used for curing the samples by 20s. For the analysis of CS, FS and ME each specimen was made from a silicone matrix addition with the stick format (2x1x7mm). On the matrix were dispensed 10 ?L of adhesive after receiving gentle air with time and temperature varying according to each group, and were cured for 20s. For analysis of CS (n=10), the specimens were fixed to the Testing Machine with a load cel of 200N, and for FS and ME (n= 5) with a load of 50N, both held at 0.5 mm/min until failure of the sample. For measurement of DC (n = 5), after volatilization, were dispensed 3 ?L of adhesive on the crystal and used Fourier Transform Infrared transmission Spectroscopy (FTIR) in the range from 1665 to 1580 cm-1. The data were subjected to three factors ANOVA and Tukey test (p <0.05). For EX and SB, the temperature of ± 40°C resulted in higher CS at all times of evaporation. The highest values of CS were observed in 20s, followed by times of 10s and 5s, respectively. Higher values of CS were found for the adhesive EX compared to SB. For GC there was no statistically significant difference for EX between the times and temperatures volatilization studied. For SB, higher values of DC were obtained with a temperature of ±40 ºC with the exception of the group volatilized of 20s, that did not differ from temperature of ±23ºC. EX presented higher values of DC followed by SB, regardless of time and temperature of volatilization. Regarding the ME, to EX, there was no statistically significant difference between the times and temperatures of volatilization. Just to SB, the temperature of ±40°C promoted an increase in the ME, and between times of volatilization there was no statistically significant difference. According to the outcome of the FS, for EX was not observed statistically significant effect between the temperatures of volatilization studied. The temperature of ± 40 ºC of SB resulted in better performance in FS. On the time of volatilization for both SB and EX, independent of volatilization temperature, the times of 20 and 10s did not differ statistically and were higher than 5s. The results of this study indicate that there is a superiority of ethanol-based adhesive on those where there is the association of ethanol and water. In general, the volatilization for 20s increased the performance of adhesive systems evaluated. Volatilization at high temperature adhesive systems based on water and ethanol, has raised its DC and the mechanical properties of them. The heated air increased CS of adhesives based on ethanol / Mestrado / Dentística / Mestre em Clínica Odontológica

Mobility has become a substantial part in our society. Since we spend a lot of our available time on the road, we expect the automotive environment to provide similar comfort levels than residential buildings. Within this context, this research thesis especially focuses on automotive thermal comfort control. The automotive cabin is a very special environment, which is characterized by extreme inhomogeneity and overall transient behavior. Thermal comfort is a very vague and a very subjective term, which depends on physiological and psychological variables. Theories for thermal comfort in transient environments have not been fully established yet and researchers are still busy with its investigation. At present, automotive industry relies on extensive thermal comfort models, manikins and powerful simulation tools to assess and control thermal comfort. This thesis studies the application of artificial intelligence and proposes a blackbox approach which aims for extracting thermal comfort knowledge directly from human's interaction with the HVAC controls. This methodology avoids the use of human physiological and psychological thermal comfort models and does not require any a-priori knowledge. A novel comfort acquisition tool has been developed and has been integrated into a research vehicle in order to gather the required data for system learning. Data has been collected during spring, autumn and summer conditions in Southern Africa. Methods of data mining have been applied and an intelligent implementation using artificial neural networks has been proposed. The achieved results are promising and allow for about 87 perecent correct classification. It is concluded that methods of artificial intelligence perform well and are far superior compared to conventional approaches. These methods can be used as a powerful tool for the development process of vehicle air-conditioning controls and have great potential for time and cost reduction.

Heat transfer characteristics associated with steam/air mixtures were studied in two pilot scale batch type steam/air retorts: a vertical positive flow retort and a horizontal forced circulation Lagarde retort. A method employing transient heat conduction into rectangular bricks of aluminum and stainless steel was developed to evaluate the surface heat transfer coefficient (h) of steam/air mixtures. A system was designed to facilitate an instantaneous drop of the test brick, from an insulated box inside the retort, into a specified steam/air medium after the come-up period. The influences of steam content, temperature, flow rate and flow direction of the heating medium and orientation of test bricks on the associated h values, temperature distribution and pressure stability in the retorts were studied. In addition, thermal processing efficacy was evaluated by measuring the rate of heat penetration into bricks of silicone rubber and rigid nylon which have thermal diffusivities in the range common for foods. In both retorts, steam content (S) of the mixture was found to be the major factor influencing h (p<0.05); however, temperature had no significant effect (p>0.05). Further, the flow direction and flow rate of the heating media in the positive flow retort, and brick orientation in the Lagarde retort also influenced h (p<0.05). The general relationship between h and S was exponential: h = a exp(bS). In the positive flow retort with the test brick in the vertical orientation, the values of a and b were 153 W/m²C and 0.0421 respectively, for steam/air media flowing in an upward direction, and were 337 W/m²C and 0.0355 respectively, for the media flowing downward. The surface heat transfer coefficient was also found to increase linearly with the medium flow rate. With the Lagarde retort, steam/air flow was always horizontal and flow rate was not adjustable. In this case, h was influenced by the test brick orientation. For bricks in the vertical orientation, the exponential parameters, a and b, were 1011 W/m²c and 0.0226 respectively, whereas in the horizontal orientation, these were 1669 W/m²C and 0.0132 Temperature distribution studies in the positive flow retort indicated that the overall standard deviation of the medium temperature at several locations during the cook period (excluding come-up) increased (p<0.05) with a decrease in the steam content and flow rate of the heating media. The effects of temperature and flow direction were nonsignificant (p>0.05). In the Lagarde retort, the temperature distribution was not influenced either by steam content or temperature of the steam/air medium. Pressure stability studies indicated that the air content and temperature of the medium increased (p<0.05) the standard deviations of retort pressure during the cook period. Based on the temperature and pressure deviations in the two retorts, steam/air mixtures with 86-90% steam contents were considered to provide satisfactory overriding air pressures for processing of retort pouches at 105-120°C. Heat penetration studies in the positive flow retort using nonpackaged test bricks of silicone rubber and nylon revealed an increase of up to 11% (p<0.05) in the heating rate index (f) of test bricks when the steam content of the media decreased from 100% to 50%. Heating of bricks at 120°C resulted in f values that were 5.5% larger (p<0.05) than those for bricks heated at 105°C. In the Lagarde retort, the effects of temperature and steam content of the media on f values were not significant. Heating bricks in the vertical orientation resulted in higher f values than in horizontal orientation in some tests, while a reverse trend was observed in others. The influence of entrapped air (15-30 mL per pouch) in retort pouches containing the bricks on f values was small when using a vertical rack that tightly constrained the bricks, whereas up to 260% higher values of f resulted when using an unconstraining horizontal rack while processing at 105-120°C in media of steam contents above 65%. These increases in f value could be prevented by using overriding air pressures of 70-100 kPa during the retort operation. The lag factor, j, was generally in the range of 0.5-1.0 for test bricks, with or without packaging, in the positive flow retort, and 0.8-1.1 in the Lagarde retort, when evaluated at 42% effectiveness for the come-up time. It was observed that in order for the j values to match the theoretical value of 1.27 for an infinite plate, the effectiveness was in the range of 60-90%. / Land and Food Systems, Faculty of / Graduate

Bibliography: pages 51-54. / The microstructure of different types of industrially produced heating elements was examined and an x-ray diffraction method was devised to determine the relative amounts of α- and β-silicon carbide present in these materials. It was confirmed that the α- to β-silicon carbide transformation occurs during heat treatment, because of the influence of the nitrogen atmosphere in the furnace. The fabrication parameters important in the manufacture of heating elements were investigated. Porous sintered silicon carbide samples were made using different proportions of grit sizes and various firing schedules. Both resistivity and crushing strength were determined. It was found that the resistivity is dependent upon degree of sintering (indicated by crushing strength) as well as the packing density of the porous body.

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The usage and applications of solar energy are numerous; however, it's still in its infancy. The subject matter discusses two applications of solar energy, a "Solar Augmented Heated System" and a "Solar Assisted Heat Pump." The solar augmented system and the solar assisted system have the same components; however, the way they are used is of primary concern. A solar system in parallel with a heat pump is called "Solar Augmented Heating System" or in series with a heat pump is a "Solar Assisted Heat Pump." A 2000 ft2 house was utilized as the basis of the design. The heating load was calculated from the construction materials. With this information the collector area, tank volume and heat pump sizes were determined. Once the system size and design was completed, TRNSYS, a "Transient Simulation Program" was used to simulate the two systems. A comparison was made of the two systems for a 21 day period to determine which of the two systems is more advantageous to use.

published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering