A preocupação com o meio ambiente deve fazer parte da rotina de uma indústria de petróleo e derivados. A presença de compostos heterocíclicos em correntes de diesel motiva a sua remoção, pois além do aspecto ambiental, esses compostos podem interferir no desempenho de processos de hidrotratamento (HDT). A adsorção é uma das opções para minimizar esse problema. Nesse contexto, o objetivo deste trabalho foi estudar o adsorvente comercial mais adequado através de um estudo cinético realizado em tanque agitado e suportado por alguns ensaios de equilíbrio. Foi dada ênfase preferencial à remoção de compostos nitrogenados, sendo avaliada a remoção de compostos sulfurados nos adsorventes mais promissores. Foram selecionados, como adsorventes comerciais, as argilas bentoníticas TCO 626G (Süd-Chemie) e F-24 (Engelhard), a -alumina CCI (Süd-Chemie), a sílica-alumina SIRAL 40 (Sasol) e a zeólita Y ultraestável USY (cedida pelo CENPES-Petrobras). Na composição do óleo diesel modelo encontra-se quinolina, carbazol e benzotiofeno, com n-hexadecano como diluente. A caracterização destes adsorventes incluiu análise química por fluorescência de raios X, análise estrutural por difração de raios X, análise textural por fisissorção de N2, análises de acidez por termodessorção de amônia (TPD de NH3) e por espectroscopia no infravermelho de piridina adsorvida. Os estudos cinéticos mostraram que a quinolina é adsorvida rapidamente, principalmente na zeolita USY, que apresentou a maior capacidade adsortiva. Observou-se que a ordem decrescente de melhor adsorvente seguiu a mesma ordem da quantidade de sítios ácidos encontrada por TPD-NH3. Nos estudos cinéticos com carbazol, a zeólita USY também foi o melhor adsorvente. Não houve acordo com relação a acidez, o que se esperava uma vez que se trata de um composto nitrogenado não básico. A presença de carbazol e quinolina na mesma solução, não alterou o desempenho da cinética de remoção de ambos, indicando que provavelmente não estão competindo pelos mesmos sítios de adsorção. Quando foi introduzido um composto sulfurado no sistema, a zeólita se manteve como o melhor adsorvente, a quinolina continuou sendo eficazmente removida, mas a remoção de carbazol sofreu alguma interferência que pode indicar a competição das moléculas pelo mesmo sítio. Nos estudos com carga real de óleo diesel, ao contrário do observado para as cargas modelo, a TCO 626G mostrou-se mais efetiva na remoção de compostos heterocíclicos que a USY. O modelo cinético proposto ajustou adequadamente as curvas e as isotermas de adsorção para quinolina e carbazol, relativas a USY e a TCO 626G, foram melhor ajustadas pelo modelo de Freundlich

Submitted by (edna.saturno@ufrpe.br) on 2017-02-15T12:33:27Z No. of bitstreams: 1 Jose Mario Baracho de Franca.pdf: 1060458 bytes, checksum: 5843154b02f16dc4ab5f2c5eaf2e0798 (MD5) / Made available in DSpace on 2017-02-15T12:33:27Z (GMT). No. of bitstreams: 1 Jose Mario Baracho de Franca.pdf: 1060458 bytes, checksum: 5843154b02f16dc4ab5f2c5eaf2e0798 (MD5) Previous issue date: 2003-08-04 / The growth of tilapia, Oreochromis spp, were evaluated in a intensive culture, from march to June 2003, through the use of twelve 5 m3 cages located at Açude Poço da Cruz (Ibimirim-PE). The experiment was designed to contain three treatments, according to the strains (Nilotica, Vermelha and Chitralada) and four replicates. Tilapia juveniles averaging 58.28, 18.74 and 63.62g, respectively, for each strain were stocked in randomly cages in a density of 600 juveniles/cage. A extruded commercial ration with 36% crude protein was used during the first 19 days, another with 32% for the subsequent 63 days and another one with 28% for the last 14 days of growout phage. Fish growth was followed through fortnightly measurements with approximately 5% of fish population. The main water quality variables were measured during the culture (temperature = 28.25 ± 0.65ºC, pH = 7.63 ± 0.38 and dissolved oxygen = 5.48 ± 0.98 mg/L) maintained adequate to the fishculture. Growth and production data were differents (P≤0.05) among treatments. Nilotica strain grew better than Chitralada than Vermelha, with respectively growth daily of 5.72, 4.60 and 3.23g/day. The final weight and weight gain were higher (P≤0.05) forNilotica (607.71g and 549.43g) than for Chitralada (504.23g and 440.61g) and Vermelha (328.79g and 335.05g). In this culture system it was possible to maintain a reasonable biomass in the cages since the final biomass were 268.68, 271.62 and 177.38Kg/cage, respectively for Nilotica, Chiralada and Vermelha. This represent a biomass of 6.99, 7.63 and 2.25Kg/m3, respectively for each strain. The feed conversion ratio was 1.85 for Nilotica, 1.77 for Chitralada and 1.86 for Vermelha strains. In spite of the fast growth, Nilotica strain showed a lower survival (73.71%) in relation with Vermelha strain, which presented the highest survival (91.29%) and lowest yield. These results shows that the tilapia Chitralada and Nilotica have a good performance for this type of culture are recommended for cage culture in a commercial scale. / O crescimento de três linhagens de tilápias, Oreochromis spp, em cultivo intensivo, de março a junho de 2003, utilizando doze tanques-rede de 5 m3, instalados no Açude Poço da Cruz (Ibimirim-PE). O experimento foi delineado para conter três tratamentos, utilizando-se as tilápias Nilótica, Vermelha e Chitralada, com quatro repetições. Juvenis de tilápia com peso médio de 58,28, 18,74 e 63,62 g, respectivamente, para os tratamentos Nilótica, Vermelha e Chitralada foram estocados aleatoriamente nos tanques-rede numa densidade de 600 juvenis/tanque-rede. Uma ração comercial extrusada com 36% de proteína bruta foi usada durante os 19 dias iniciais, outra com 32% para os 63 dias subseqüentes e uma com 28% para os últimos 14 dias da fase de engorda. Foi acompanhado o crescimento dos peixes com amostragens quinzenais, de aproximadamente 5% de população. As principais variáveis de qualidade de água medidas durante o cultivo (temperatura = 28,25 ± 0,65ºC; pH = 7,63 ± 0,38 e oxigênio dissolvido = 5,48 ± 0,98mg/L) mantiveram-se adequadas para o cultivo de peixes. Os dados de crescimento e produção foram diferentes (P≤0,05) entre os tratamentos. A tilápia Nilótica apresentou maior crescimento (5,72 g/dia) em relação à Chitralada (4,60 g/dia) e a Vermelha (3,23 g/dia). O peso final e ganho de peso foram maiores (P≤0,05) para Nilótica (607,71g e 549,43g) que para Chitralada (504,23 e 440,61g) e a Vermelha (328,79g e 335,05g). Neste sistema de cultivo foi possível manter uma biomassa razoável, sendo registrada uma biomassa final de 268,68; 271,62 e 177,38 Kg/tanque-rede, respectivamente, para as tilápias Nilótica, Chitralada e Vermelha, o que correspondeu a 6,99, 7,63 e 2,25Kg/m3 para as respectivas linhagens. A conversão alimentar foi de 1,85 para Nilótica, 1,77 para Chitralada e 1,86 para a Vermelha. Apesar do melhor crescimento da Nilótica, constatou-se uma menor sobrevivência (73,71%) em relação à linhagem Vermelha (91,29%), que apresentou baixo rendimento de cultivo. Diante dos resultados constata-se um melhor desempenho para as tilápias Nilótica e Chitralada, sendo portanto recomendadas para o cultivo comercial em tanques-rede.

O objetivo principal deste trabalho foi caracterizar a estrutura da rede de armazenamento de álcool combustível brasileira destacando-se a infra-estrutura da região Centro-Sul no que diz respeito à capacidade estática e à localização dos tanques das unidades produtoras, distribuidoras e portos, além do cálculo e análise do índice de concentração dos principais agentes do setor nessa região. Para o estudo dos Índices de Concentração CR4 e do Índice de Herfindahl-Hirschiman HHI, utilizou-se a capacidade de armazenagem de álcool das unidades produtoras em nível estadual de detalhamento dos dados; a produção de álcool no ano-safra canavieiro de 2007/2008; a tancagem individual das unidades produtoras, dos terminais portuários e das bases distribuidoras. O levantamento realizado indicou que a maior concentração de usinas encontra-se na região Centro-Sul, com grande destaque para o estado de São Paulo que, além de possuir o maior número de unidade produtoras, também classifica-se como maior estado produtor e o que possui a maior tancagem. Nas colocações subseqüentes estão os estados de Minas Gerais e Paraná. Com capacidades de armazenagem menores ficam os estados de Goiás, Mato Grosso, Mato Grosso do Sul, Espírito Santo e Rio de Janeiro. O Índice de Concentração CR4 para a região Centro- Sul indicou que a maior concentração encontra-se entre as duas maiores empresas e que, à medida que mais empresas são adicionadas, a taxa de aumento do índice é menor, apontando para uma estrutura de mercado onde existem algumas empresas líderes, com grande participação na capacidade de armazenagem de álcool no setor sucroalcooleiro e um grande número de médias e pequenas empresas com menor participação no mercado. Especificamente no estado de São Paulo, o Índice de Concentração CR4 do setor equivale à metade de toda a capacidade de armazenagem de álcool do estado e tratam-se das mesmas empresas que compõem as quatro maiores de toda a região Centro-Sul. Em relação à rede armazenadora de álcool nos portos da região, o porto de Santos, no estado de São Paulo, obteve a maior concentração, seguido do Porto de Paranaguá no estado do Paraná. As bases distribuidoras de combustível que movimentam álcool combustível configuraram maior concentração no Estado de São Paulo, seguido do Paraná e Rio de Janeiro. / The main objective of this work was characterize the Brazilian ethanol storage chain, focusing on the centersouth infrastructure area, looking at the static capacity and the tanks localization of the unit production, distributor and ports besides, the calculation and the concentration degree of the main sector agents in this area. To study the four biggest group Concentration Index CR4 and the Herfindahl-Hirschiman index HHI, it was used the ethanol storage capacity per unit, in a state level of details; the ethanol production in the sugar cane season 2007/2008; the individual production of the unit storage, the ports and the distributor bases. The survey realized has shown that the biggest unit concentration is located inside the Center-South area, with main focus in São Paulo state, that has the biggest number of units, the biggest ethanol production and also the biggest storage. After that, its got Minas Gerais State and Paraná state. Goiás, Mato Grosso, Mato Grosso do Sul, Espírito Santo and Rio de Janeiro have the smallest capacities. The Concentration Index CR4 for the Center-South indicated that the biggest concentration is between two biggest enterprises, and, by the time that more enterprises are included, the index rate growth is smaller, pointing to market structure where it exists a small group of leaders companies with big participation in the ethanol storage capacity. In other hand, a big group of small and medium units have smaller market participation. Specifically in São Paulo state, the Concentration Index CR4 of the sector is equivalent to half of all ethanol storage capacity of this state and is about the same companies that are included in the four biggest units of the center-south area. Related to the ethanol storage chain at the ports, the Santos port, in São Paulo State, has the biggest concentration followed by Paranaguá port, in Paraná State. The fuel distribution bases that movement ethanol has bigger concentration in São Paulo State followed by Paraná State and Rio de Janeiro State.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O cultivo de rosas (rosa sp). caracteriza-se pela sua elevada rentabilidade, em comparaÃÃo com cultivos tradicionais, entretanto, o manejo e a pÃs-colheita exigem do produtor conhecimento tÃcnico aprimorado. Por sua vez, diversas tÃcnicas empregadas no manejo na cultura tem se caracterizado pelo seu empirismo, necessitando-se de estudos. Com o objetivo de apresentar sugestÃes aos produtores para um manejo hÃdrico, volume de substrato e nÃmero de drenos adequados por vaso, elaborou-se este trabalho por meio de dois experimentos nos quais foram analisados os efeitos desses fatores sobre a produtividade da roseira, em ambiente protegido. Os experimentos foram conduzidos na Empresa Reijers, no municÃpio de SÃo Benedito-CE. No primeiro, com delineamento experimental em blocos ao acaso, utilizaram-se cinco tratamentos (nÃveis de irrigaÃÃo correspondentes a 60%, 80%, 100%, 120% e 140% da evaporaÃÃo medida no tanque classe âAâ, ECA) e com quatro repetiÃÃes. Como conclusÃes obtiveram-se: a utilizaÃÃo do tanque Classe âAâ no manejo de irrigaÃÃo de rosas à viÃvel para o produtor, pois possibilita a obtenÃÃo de elevadas produtividades; a aplicaÃÃo de lÃminas elevadas pelos produtores reduz o nÃmero de hastes de 50, 60cm e total por vaso. No segundo, com delineamento experimental fatorial 3 x 2, analisou-se os efeitos de trÃs volumes de substrato (3, 4 e 6 litros por planta) e de duas quantidades de drenos por vaso (1 e 8) sobre o nÃmero de hastes por vaso da roseira, em ambiente protegido. Obtiveram-se as seguintes conclusÃes: os menores volumes de substrato por planta proporcionam um maior nÃmero de hastes por vaso, mas com predomÃnio de hastes de menor valor comercial. Jà a utilizaÃÃo de maiores volumes de substrato por planta pelo produtor resulta em um menor nÃmero de hastes por vaso, mas em um maior nÃmero de hastes de maior valor comercial. A utilizaÃÃo pelo produtor de vasos com um maior nÃmero de drenos reduz o nÃmero total de hastes por vaso. Para uma maior produÃÃo de hastes em vasos de 12 L, o produtor de roseira deve plantar trÃs plantas (4 litros de substrato por planta) em vasos com um dreno. / The cultivation of roses (roses sp) is characterized by its high profitability, in comparison with traditional cultivations, however, the handling and the powder-crop demand from the producer perfect technical knowledge. For its time, several employed techniques in the handling in the culture have if characterized by its empiricism, being needed studies. With the objective of presenting suggestions to the producers for a handling hydric, substratum volume and number of appropriate drains for vase adapted, this work was elaborated through two experiments where the effects of those factors were analyzed upon the productivity of the rosebush, in a protected atmosphere. The experiments were conducted in the Reijers Company, in the municipal district of SÃo Benedito-CE. In the first experiment, using experimental maping in blocks at random, five techniques were used (irrigation levels corresponding to 60%, 80%, 100%, 120% and 140% of the evaporation measured in the tank class "A", ECA), all processes were conducted four times. The conclusions were obtained: the use of the tank Class "A" in the handling of irrigation of roses is viable for the producer, because it makes possible the obtaining high productivities; the application of higher volumes of water by the producers reduces the number of stems of 50cm, 60cm and the total production per vase. In the second experiment, using factorial experimental maping 3 x 2, where were analyzed the effects of three substratum volumes (3, 4 and 6 liters for plant) and of two types of vases with 1 and 8 drains, over the number of stems per vase of the rosebush, in a protected atmosphere. The following conclusions were obtained: the smallest substratum volumes for plant provide a larger number of stems per vase, but with prevalence of stems of smaller commercial value. On the contrary, the use of larger substratum volumes per plant by for the producer results in a smaller number of stems per vase, but in a larger number of stems of larger commercial value. The use of vases with a larger number of drain by producer, reduces the total number of stems for vase. For a larger production of stems in vases of 12 L, the producer of rosebushes should plant three plants (4 liters of substratum for plant) in vases with a single drain.

O presente trabalho aborda o desenvolvimento de um sistema de automação e controle para tanques oceânicos com múltiplos atuadores para possibilitar a geração e absorção ativa de ondas. O desenvolvimento compreende: a implementação e a validação do sistema de automação e controle para o tanque de provas; o desenvolvimento de algoritmos para a geração de ondas com batedores do tipo flap, para atender aos casos tipicamente utilizados em ensaios de estruturas oceânicas, tais como ondas regulares e irregulares, com ou sem espalhamento direcional. O sistema desenvolvido fez uso de controladores do tipo CLP (controlador lógico programável) em rede de comunicação industrial usando troca de dados síncrona, como uma solução robusta de automação. Os controladores desenvolvidos foram estudados individualmente para a devida caracterização e identificação dos limites de desempenho. Sensores de ondas ultrassônicos foram desenvolvidos e caracterizados para medir ondas nos atuadores e viabilizar a malha de controle de absorção ativa do tanque de provas. Sensores de ondas capacitivos foram desenvolvidos e calibrados para a medição de ondas nos ensaios experimentais. A validação experimental do funcionamento do sistema de atuação, controle e sensoriamento foi realizada utilizando os equipamentos desenvolvidos. Os testes foram feitos validando o funcionamento dos atuadores, a geração de ondas regulares, a geração de ondas regulares oblíquas e a geração de ondas irregulares de cristas longas. Os testes apontaram que os atuadores dos cantos do tanque, que são fixos, provocam alterações no campo de ondas, tal como a difração de ondas. As flutuações foram avaliadas onde os valores extremos podem chegar a 58% e foi apresentada uma proposta de medidas paliativas. As ondas regulares e irregulares foram validadas para que o tanque seja capaz de realizar ensaios experimentais reproduzindo as condições ambientais da costa brasileira em ensaios com modelos reduzidos. Foram realizadas medições do coeficiente de reflexão das ondas regulares e irregulares geradas no tanque de provas que mostram valores em torno de 10%. Usando a absorção ativa de ondas em duas laterais opostas do tanque, constatou-se que a segunda reflexão (re-reflexão) afeta fracamente o campo de ondas. A fim de demonstrar o potencial do controlador do tanque, foi desenvolvida uma nova técnica para focalização de energia de ondas em tanque de provas, fundamentada na técnica de TR (time reversal), para concentrar ondas em pontos específicos do espaço. Esta técnica foi originalmente proposta para aplicações usando ultrassom na forma de ondas de pressão acústica, mas, devido à semelhança do fenômeno físico, a técnica foi aplicada às ondas de superfície livre da água. Foram realizados três tipos de testes usando TR, e em todos eles a concentração de ondas foi obtida no local e no instante esperados. Concluiu-se, então, que o método funciona mesmo que existam obstáculos à propagação da onda, como difração e reflexão no interior do tanque de provas. Um dos testes estudou as ondas concêntricas geradas por um objeto lançado contra a água; a aplicação de TR resultou em uma onda concentrada no ponto de lançamento. Os fenômenos observados podem servir de paradigma para comparações numéricas e estudos de ondas em meios dispersivos. / This work discusses the development of an automation and control system for ocean tanks with multiple actuators to enable the generation and active absorption of waves. The development includes: implementation and validation of system automation and control to the ocean wave tank, the development of algorithms for generating waves with flap type wave generator for dealing with cases typically used in tests of ocean structures, such as regular waves and irregular, with or without directional spreading. The developed system used PLC controllers (programmable logic controller) and an industrial communication network with synchronous data exchange, which is a robust automation system solution. The developed controllers were individually studied for proper performance characterization. Ultrasonic wave sensors have been developed and characterized to measure waves in the face of actuators and enable the control loop active absorption of the ocean wave tank. Capacitive wave sensors have been developed and calibrated to measure wave in experimental tests. The experimental validation of system actuation, control and sensing system was performed. Validation tests of the operation of the actuators under regular wave generation, irregular wave generation and oblique regular waves were done. The tests showed that the fixed actuators of the corners of the tank cause changes in the wave field such as diffraction waves. The spatial wave field fluctuations can reach 58% and correction procedures were proposed. Regular and irregular waves were validated for the tank to be able to perform experimental tests reproducing the environmental conditions of the Brazilian coast in reduced model tests of offshore structures. Measurements of the reflection coefficient of regular and irregular waves generated in the test tank indicated values around 10%. Using active absorption of waves in two opposite sides of the tank, it was realized that the re-reflection weakly affects the wave field. In order to demonstrating the innovative potential applications of tank, it was developed a new technique to focus wave energy, based on the technique of TR (time reversal) to concentrate waves at specific points in space. This was originally proposed for applications using ultrasound acoustic pressure waves, but due to the similarity of the physical phenomenon, the technique was applied to the waves in the free water surface. Three types of tests were carried out and in each TR concentration wave was obtained in the expected location and the expected time. It was noticed that the method also works even with obstacles to wave propagation, such as diffraction and reflection inside the ocean wave tank. An object thrown against the water, creating concentric waves was studied and after the application of TR resulted in a wave concentrated at the same splash point. The observed phenomena can be considered as a paradigm for numerical comparisons and studies of waves in dispersive media.

The objective with this thesis is to build a Black-Box model of the tank pressurization system in JAS 39 Gripen. This model is intended to be used in an existing diagnosis system for the security control in the tank pressurization system. The tank pressurization system is a MIMO system. This makes the identification process more complicated when the best model is to be chosen. In this master's thesis the identification procedure for a MIMO system can be followed. Testing of the diagnosis system with the created Black-Box model shows that the model seems to be good enough. The diagnosis system takes the right decisions in the performed simulations. This shows that system identification might be a good alternative to physical modelling for a real-time model. The disadvantage with the Black-Box model is that it is less accurate in steady-state than the physical model used before is. The advantage is that it is faster than the physical model. The diagnosis system and the model developed in this thesis are not directly applicable on the real system today. The model has to be redesigned on the real system, this is also the case for the diagnosis system. The diagnosis system also has to be redesigned, so general flight cases, not only the security control can be supervised. However, experiences and choices like input and output signals, and choice of sample interval can be reused from this thesis when a new model might be developed.

Liquid sloshing in a 2D tank applied on a wave energy capture system and reducing the oscillation of an offshore platform are discussed in this study. A fully nonlinear time-independent finite difference method and the forth-order Runge-Kutta method are implemented to solve the coupled motions of liquid sloshing in a 2D tank with a floating platform. When the external forcing frequency of the Dynamic Vibration Absorber System composed by a tuned liquid damper and a tuned mass damper is identical to the fundamental frequency of the tank, the external force can be effectively diminished by the sloshing-induced force. In the meantime, the maximum effect of tuned mass damper on reducing the amplitude of the floating platform appears. When the frequency of external forcing is close to the first natural frequency of the liquid tank, the coupled effect between the motions of both the tank and the platform can effectively reduce the vibration of the platform and the total energy of the whole system. The Eigenfrequency of a wave capture system is formed by the coupled effect of a liquid tank and a wave capture system. When the excitation frequency of the wave capture system is near its Eigenfrequency, the sloshing-induced force is much larger than that of external and the maximum displacement of the wave energy capture system occurs. As a result, the wave energy capacity of the wave capture system can be averagely increased to 150% by the influence of liquid sloshing in the tank.

Reliability is one of the most critical performance measures of guided missile systems. It is directly related to missile mission success. In order to have a high reliability value, reliability analysis should be carried out at all phases of the system design. Carrying out reliability analysis at all the phases of system design helps the designer to make reliability related design decisions in time and update the system design. In this study, reliability analysis process performed during the conceptual design phase of a Medium Range Anti-Tank Missile System Inertial Measurement Unit (IMU) was introduced. From the reliability requirement desired for the system, an expected IMU reliability value was derived by using reliability allocation methods. Then, reliability prediction for the IMU was calculated by using Relex Software. After that, allocated and predicted reliability values of the IMU were compared. It was seen that the predicted reliability value of the IMU did not meet the required reliability value. Therefore, reliability improvement analysis was carried out.

Estimation of the total mission life of a spacecraft is an important issue for the communication satellite industries. For accurate determination of the remaining mission life of the satellite it is essential to estimate the amount of propellant present in the propellant tank of the spacecraft at various stages of its mission life. Because the annual revenue incurred from a typical communication satellite operating at its full capacity is on the order of millions of dollars, premature removal of spacecraft from their orbits results in heavy losses. Various techniques such as the bo okkeeping method, the gas law method, numerical modeling techniques, and use of capacitive sensors have been employed in the past for accurate determination of the amount of propellant present in a spacecraft. First half of the thesis is concerned with sensitivity analysis of the various propellant gauging techniques, that is, estimating the e ects of the uncertainty in the instruments employed in the propellant gauging system on the onboard propellant estimation. This sensitivity analysis is done for three existing propellant gauging techniques – gas injection method, book-keeping method and the propellant tank heating method. A comparative study of the precision with which the onboard propellant is estimated by the three techniques is done and the primary source of uncertainty for all the three techniques is identified. It is illustrated that all the three methods — the gas injection method, the book-keeping method and the propellant tank heating method — are inherently indirect methods of propellant gauging, as a consequence of which, the precision with which the three techniques estimate the residual propellant decreases towards the end of mission life of the spacecraft. The second half of the thesis explores the possibility of using a new propellant tank configuration, consisting of a truncated cone centrally mounted within a spherical propellant tank, to measure the amount of liquid propellant present within the tank. The liquid propellant present within the propellant tank orients itself in a geometry, by virtue of its dominant surface tension force in zero-g condition, which minimizes its total surface energy. Study reveals that the amount of liquid propellant present in the tank can thus be estimated by measuring the height of the propellant meniscus within the central cone. It is also observed that, unlike gas law metho d, bookkeeping method or the propellant tank heating metho d, where the precision of the estimated propellant fill-fraction decreases towards the end-of-life of the spacecraft, for the proposed new configuration the precision increases.

Estimation of the total mission life of a spacecraft is an important issue for the communication satellite industries. For accurate determination of the remaining mission life of the satellite it is essential to estimate the amount of propellant present in the propellant tank of the spacecraft at various stages of its mission life. Because the annual revenue incurred from a typical commu-nication satellite operating at its full capacity is on the order of millions of dollars, premature removal of spacecraft from their orbits results in heavy losses. Various techniques such as the bookkeeping method, the gas law method, numerical modeling techniques, and use of capacitive sensors have been employed in the past for accurate determination of the amount of propellant present in a spacecraft. First half of the thesis is concerned with sensitivity analysis of the various propellant gauging techniques, that is, estimating the effects of the uncertainty in the instruments employed in the propellant gauging system on the onboard propellant estimation. This sensitivity analysis is done for three existing propellant gauging techniques – gas injection method, book-keeping method and the propellant tank heating method. A comparative study of the precision with which the onboard propellant is estimated by the three techniques is done and the primary source of uncertainty for all the three techniques is identified. It is illustrated that all the three methods — the gas injection method, the book-keeping method and the propellant tank heating method — are inherently indirect methods of propellant gauging, as a consequence of which, the precision with which the three techniques estimate the residual propellant decreases towards the end of mission life of the spacecraft. The second half of the thesis explores the possibility of using a new propellant tank configuration, consisting of a truncated cone centrally mounted within a spherical propellant tank, to measure the amount of liquid propellant present within the tank. The liquid propellant present within the propellant tank orients itself in a geometry, by virtue of its dominant surface tension force in zero-g condition, which minimizes its total surface energy. Study reveals that the amount of liquid propellant present in the tank can thus be estimated by measuring the height of the propellant meniscus within the central cone. It is also observed that, unlike gas law method, bookkeeping method or the propellant tank heating method, where the precision of the estimated propellant fill-fraction decreases towards the end-of-life of the spacecraft, for the proposed new configuration the precision increases.