In this thesis we examine the feasibility of developing a white light source capable of producing colors between 2500 and 7500 Kelvin on the black-body radiator spectrum by simply adjusting amperage to a blue and ultraviolet (UV) light emitting diode (LED). The purpose of a lighting source of this nature is to better replicate daylight inside a building at a given time of day. This study analyzes the proposed light source using a 385 nm UV LED, a 457 nm blue LED, a 479 nm blue LED, a 562 nm peak cerium doped yttrium aluminum garnet (YAG:Ce) phosphor, and a 647 nm peak selenium doped zinc sulfide (ZnS:Se) phosphor. Our approach to this study initially examined optical performance of yellow-emitting phosphor (YAG:Ce) positioned at specific distances above a blue LED using polydimethylsiloxane (PDMS) as a substrate. An understanding of how phosphor concentration within the PDMS, the thickness of the PDMS, and how substrate distance from the LED die affected light intensity and color values (determined quantitatively by utilizing the 1931 CIE 2° Standard Observer) enabled equations to be developed for various lens designs to efficiently produce white light using a 457 nm peak wavelength LED. The combination of two luminescent sources (457 nm LED and YAG:Ce) provided a linear trend on the 1931 CIE diagram which required a red illumination source to obtain Kelvin values from 2500 to 7500. Red-emitting phosphor (ZnS:Se), selected to compliment the system, was dispersed with YAG:Ce throughout PDMS where they were stimulated with a blue LED thereby enabling all desired Kelvin values with differing concentration lenses. Stimulating ZnS:Se with the addition of a UV LED did not provide the ability to change the color value of the set up to the degree required. Many other factors resulted in the decision to remove the UV LED contribution from the multi-Kelvin light source design. The final design incorporated a combination of ZnS:Se and YAG:Ce stimulated with a blue LED to obtain a 2500 Kelvin value. A separate blue LED provides the means to obtain 7500 Kelvin light and the other color values in between, with a linear approximation, by adjusting the amperages of both LEDs. In addition to investigating the feasibility of obtaining the Kelvin values from 2500 to 7500, this thesis also examined the problem of ZnS:Se’s inability to cure in PDMS and a method to create a lens shape to provide equal color values at all points above a phosphor converted LED source. ZnS:Se was found to be curable in PDMS if first coated with a low viscosity silicon oil prior to dispersion within PDMS. The lens configuration consists of phosphors equally distributed in PDMS and cured in the shape of a Gaussian distribution unique to multiple factors in LED-based white light design.

This thesis explores the potential of utilizing metal-based plasma sources as a sustainable solution for high-powered electric propulsion and its implications for future interplanetary travel. Focusing on the Vacuum Arc Thruster and the Variable Specific Impulse Magnetoplasma Rocket engine, the study encompasses numerical simulations, analytical comparisons, and performance analyses to assess the feasibility of metal plasma fuels in space missions.The numerical analysis employs COMSOL Multiphysics to delve into the magnetohydrodynamics behavior within the VAT. Such simulation setup could provide valuable insights. Although the numerical results are disappointing for this paper, there exist possibilities within future work. The main hurdle is the simulation of vacuum. There are workarounds in COMSOL's Vacuum System Modeling tool which was not available for this thesis. Also, the used material properties were not suited for this high temperature plasma environment. The lack of material properties is a consequence of the insufficient research in the metal plasma field.Performance analysis is conducted on both the VAT and VASIMR engine, exploring efficiency, thrust capabilities, and feasibility for interplanetary missions. The results demonstrate the potential of metal-based plasma sources to reduce dependence on Earth for refueling and decrease mission costs. It is found that aluminum and magnesium have similar performance as the argon gas used in the VASIMR.Although challenges exist, such as integration problems and availability of material properties for metals in plasma states, the study underscores the promise of metal plasma fuels for sustainable space exploration. By advancing high-powered electric propulsion technologies, we move closer to realizing humanity's ambitious journey to distant celestial bodies. This research paves the way for future innovations, enabling a more self-sustaining space economy and unlocking new horizons of interplanetary travel.

Submitted by Claudio Wanderley (claudio.burian@fjp.mg.gov.br) on 2010-06-10T14:04:29Z No. of bitstreams: 1 tese_Claudio_Burian_Wanderley.pdf: 875614 bytes, checksum: dc145cd22b82eaa33bc4cda649abe175 (MD5) / Approved for entry into archive by Daniella Santos(daniella.santos@fgv.br) on 2010-06-10T14:10:02Z (GMT) No. of bitstreams: 1 tese_Claudio_Burian_Wanderley.pdf: 875614 bytes, checksum: dc145cd22b82eaa33bc4cda649abe175 (MD5) / Made available in DSpace on 2010-06-14T19:17:12Z (GMT). No. of bitstreams: 1 tese_Claudio_Burian_Wanderley.pdf: 875614 bytes, checksum: dc145cd22b82eaa33bc4cda649abe175 (MD5) Previous issue date: 2009-12-11 / This thesis aims to discuss municipal public finance issues. An improvement of the Brazilian fiscal federalism, with greater resources decentralization and the implementation of high-powered rules for the federative transfers may be an important tool in the improvement of our social conditions. To do so, this thesis was divided into four distinct parts. The first chapter discusses the oil revenues impacts on unicipalities’ public finance. The legal changes that occurred in Brazil in the nineties in the oil and gas sector led to increasing royalties transfers to Brazilians states and municipalities. The annedoctical evidence that this transfers are not been used properly - in a way that would increment the local welfare - have originated a important discussion about these distribution rules. This paper tries to identify this revenues impacts over others municipalities’ fiscal variables. It seems that this did not impact the others sources of municipalities revenue. Unhappily, some of the resources (which distribution is either more or less concentrated) led the municipalities to increase their current expenditures and diminishes their investments efforts. At the same time, they are not spending this extra money in a way that would increment the local welfare. On the other hand, the resources which distribution is between these two limits has the opposite effect. The second chapter discusses the impact of oil revenues on the proficiency of fourth grade students of primary public schools. The oil revenues - bundled or not - were not statistically significant in explaining the observed student performance in Portuguese and mathematics. This result, however, must be analyzed with caution, since it is not trivial to identify how (and when) these effects would be generated. However, different sources of municipal revenue would impact differently the students’ proficiency scores, explaining why we need to better understand these differences to design more efficient constitutional transfer mechanisms to the municipalities. In the third chapter, we study the impacts of municipal emancipation occurred in the 90s on the well-being of local populations. More than a thousand of new municipalities were created at the nineties in Brazil, due the new Federal Constitution of 1988. There is anecdotic evidence that this was a pretty harmful process for the Brazilian welfare, but there were no systematic attempt to valuate it properly. This paper tries to do so using data from Minas Gerais municipalities which number has grown from 723 to 853 ones in that decade. The results suggest that this process strongly improved the welfare of the local population. This implies that local political markets are efficient and it should be allowed for any district to emancipate from its former municipalities, if their population wishes to do so. Finally, in the fourth chapter we analyze the impact of law (implemented in Minas Gerais) who sought to increase the incentives pro-efficiency of municipal governments. In order to improve the welfare of its citizens, the state government of Minas Gerais (Brazil) has imposed, at 1995, the state law 12.040, known as Robin Hood law. It stated that 25% of the revenue transferred to the municipalities should be allocated through observable results achieved in education, health, environment among others. In other words, this law established a high power contract between the state government and the municipalities, which is not very usual. This study shows that this law had a significant impact on the municipalities’ education and health. But it’s necessary to redesign these transfers’ rules, in order to improve its power and its results. These results shows that the use of high powered rules in federative transfers could be a strong mechanism in order to improve the population welfare. / Esta tese busca discutir problemas relacionados às finanças públicas municipais no país. Um aprimoramento de nosso federalismo fiscal, com maior descentralização de recursos e implementação de regras de transferências federativas com maiores incentivos pró-eficiência – aumentando os incentivos pró-obtenção de melhores resultados sociais por parte das unidades subfederadas – pode se revelar instrumento importante na melhoria de nossas condições sociais. Para isto, dividiu-se esta tese em quatro partes distintas. No primeiro capítulo, discutem-se os impactos das receitas petrolíferas sobre as finanças públicas municipais. As mudanças legais ocorridas no país na década de noventa do último século - relativas ao setor petrolífero - levaram a crescente (e concentrada) transferência de recursos do setor para os estados e municípios brasileiros. A forte sensação que estes estariam sendo desperdiçados de alguma forma vem suscitando discussões sobre a necessidade de se reformular sua distribuição. As recentes descobertas de megacampos petrolíferos no pré-sal do litoral brasileiro somente intensificaram este processo. Buscou-se identificar os efeitos destas transferências sobre as variáveis fiscais municipais no país. Detectou-se que não ocorreu substituição tributária, ou seja, estes recursos não diminuíram o esforço arrecadatório dos municípios. Em compensação, tanto os recursos cuja distribuição é bem mais concentrada (referentes aos royalties excedentes) quanto aqueles mais bem-distribuídos (referentes aos royalties originais) levaram as prefeituras a aumentar seus gastos correntes (piorando sua composição do ponto de vista social) e diminuir seus investimentos. O contrário parece ocorrer com os recursos cuja distribuição se dá de forma intermediária (os royalties referentes às participações especiais). No segundo capítulo, discute-se o impacto das receitas petrolíferas sobre a proficiência dos alunos até a quarta série primária das escolas públicas municipais. As receitas petrolíferas – agregadas ou não – não se mostraram estatisticamente significativas na explicação do desempenho observado pelos alunos da quarta série primária das escolas municipais em português ou matemática. Este resultado, entretanto, deve ser olhado com cautela, uma vez que não é trivial identificar como (e o tempo necessário) estes efeitos seriam gerados. Entretanto, diferentes fontes de receitas municipais impactariam de forma diferenciada as proficiências observadas nos testes de português e matemática, explicitando a necessidade de se entender melhor estas diferenças para se desenhar mecanismo mais eficiente de repasse de recursos constitucionais aos municípios. No terceiro capítulo, estudam-se os impactos das emancipações municipais ocorridas na década de 90 sobre o bem-estar das populações locais. Devido à Constituição Federal de 1988, o número de municípios no Brasil multiplicou-se fortemente na década de 90 do último século. Mais de mil municípios foram criados em todo o país, fazendo seu número ultrapassar a casa dos 5.500. Este processo tem sido interpretado de forma bastante negativa. Baseado em evidências anedóticas, se pressupõe que os atores políticos locais o utilizaram para se apropriar de maior parcela dos recursos transferidos de outros níveis governamentais. Entretanto, nenhum esforço mais sistemático foi realizado buscando calcular, de maneira efetiva, os resultados sociais líquidos deste processo. É isto que se busca fazer aqui, utilizando dados sobre os municípios mineiros - cujo número passa de 723 em 1991 para 853 em 2000. Foram detectados impactos positivos relacionados a diversas variáveis educacionais e de saúde. Ao mesmo tempo, o contrário ocorreu com os indicadores de pobreza e indigência. Este resultado mostra que o movimento observado de emancipação municipal talvez tenha sido bastante benéfico, sinalizando para a existência de mercados políticos eficientes nestas localidades, o que indicaria a necessidade de se manter uma maior autonomia local relativa a processos de emancipação de distritos. Por fim, no quarto capítulo, analisam-se os impactos de lei (implementada em Minas Gerais) que buscou aumentar os incentivos pró-eficiência das prefeituras municipais a partir das transferências federativas. Buscando melhorar as condições de vida dos municípios mineiros, o governo estadual mineiro instituiu, em 1995, a lei 12.040, conhecida como Lei Robin Hood. Esta permitia que 25% dos recursos de ICMS a serem distribuídos aos municípios mineiros se dessem sobre resultados observáveis em diversas áreas tais como saúde, educação, conservação ecológica, entre outras. Ou seja, esta instituía, em relação a estas transferências, um contrato de alto poder com os municípios relacionados às políticas públicas implementadas. O estudo destas transferências (relativas à educação e saúde) mostrou resultados dúbios. Resultados positivos relativos à educação e à saúde parecem ocorrer em todo o estado, mas os incentivos dados poderiam ser bem maiores - faz-se necessário um refinamento das regras da partilha destas transferências. Dada a relativa escassez deste tipo de contrato em transferências federativas, seja no Brasil, seja no restante do mundo, este resultado aponta a necessidade de utilização de instrumentos de maior poder nas relações federativas, buscando incrementar as condições de vida locais.

In the stories of olden times and in those of our own American Indians, we learned of the picture writing of primitive peoples. It became an early method of recording people's thoughts. This was a very useful method at a time when the race was young. This in turn was the beginning of our alphabet, later the beginning of shaping letters into words, and then word into sentences and paragraphs. As our world has grown older, new idea have come into use and we are no longer content to live as our grandparents lived. We travel by fast express trains, high powered auto- mobiles, airplanes, or zeppelins. The radio gives us the news before our papers containing it are on the street. are not able to talk with people on the other side of the world. Business men find this a very valuable means of doing business when time means money. The motion pictures bring us the story of the book we have not had time to read and the characters from its pages talk to us from the screen. In short, we must have quicker ways of doing things.