https://tedebc.ufma.br/jspui/handle/tede/3626 2026-04-14T22:30:15Z https://tedebc.ufma.br/jspui/handle/tede/5756 Título: MODELAGEM E ALGORITMOS DE CONTROLE ROBUSTO NEURO-ADAPTATIVO PARA FOGUETES DE COMBUSTÍVEL SÓLIDO ESTUDO DE CASO: CONTROLADOR BASEADO EM MODELO DE REFERÊNCIA COM RNA-RBF PARA CONTROLE DE ALTITUDE Autor: CARVALHO, Christian Danner Ramos de Primeiro orientador: FONSECA NETO, João Viana da Abstract: This dissertation presents the development of a methodology for designing robust neuro- adaptive controllers, based on a reference model associated with an artificial neural network of radial basis functions (ANN-RBF) for solid fuel suborbital rockets. The modelling and neuro-adaptive robust control algorithms for these rockets are presented. Initially, the methodology is evaluated for a robust controller based on a reference model with ANN-RBF for altitude control. The main objective of the control is to be able to suppress the effect of non-linear uncertainties inherent in the process. The method involves mathematical and computational modelling, together with the design of adaptive controllers for stability and performance analysis. The controllers considered include MRAC (Model Reference Adaptive Control) techniques and an MRNAC (Model Reference Neuro-Adaptive Control) approach. The analysis, carried out using computer simulations, evaluates the behaviour of each controller in relation to system stability and performance. The final objective is to select the most suitable controller for the suborbital rocket, taking into account the system constraints, robust performance requirements, robust stability and optimal adaptability. This research promotes the development of adaptive controllers for suborbital rockets, with possible applications in scientific research and commercial launches. Instituição: Universidade Federal do Maranhão Tipo do documento: Dissertação 2024-07-08T00:00:00Z https://tedebc.ufma.br/jspui/handle/tede/5480 Título: SIMULAÇÃO TÉRMICA E GERAÇÃO DE ENERGIA DE UM CUBESAT Autor: SANTANA, André Luís Rodrigues Primeiro orientador: SOUZA, Francisco das Chagas de Abstract: CubeSat is a standard satellite based on the dimensions of a cube with 10 × 10 × 10 cm, about which academia and industry have already carried out several successful missions in the last decade and still have significant growth potential in the coming years. In space, these small satellites must survive in the vacuum environment, with intense temperature variation and thermal gradient, usually above 60◦C and, in a few minutes, below-30◦C. One of the critical subsystems of CubeSat is thermal control, which maintains temperature stability between the operational bands of the subsystems. Another equally critical subsystem is the power system, responsible for generating electrical energy used during the orbit. This dissertation focuses on the thermal and power simulation of a typical CubeSat 1U. The heat transfer simulation is divided between the irradiance and thermal models. The irradiance model determines the magnitude of heat sources, which are made up of solar radiation, albedo, and infrared emission from the earth; such sources depend on the attitude model (Pointing of CubeSat), orbit (orbital dynamics), and altitude (vertical distance). From the variation of the model, different thermal scenarios faced by CubeSat along the orbit are investigated. Then, to investigate heat transfer in space, a thermal model based on the Finite Volumes Method (FVM) is structured, using the irradiance model as a contour condition on the external surfaces of the solar panel. In total, five orbits are simulated: maximum solar exposure with eclipse (MES-0), maximum sun exposure without eclipse (MES-90), detumbling with eclipse (DET-0), detumbling without eclipse (DET-90), and maximum exposure to the eclipse coupled to a heat tube (MES-0-HP). In addition, recognizing that heat is an energy source, this work simulates a thermoelectric generator (TEG) coupled to the CubeSat, evaluating the potential of TEG for power generation. The results indicate that the different scenarios of the orbit impact the power generation and thermal control of CubeSat, being essential to predict the thermal conditions for the design of small satellites. During thermal simulations, a heat tube (HP) between solar panels is considered in the model, improving the power generation and performance of the photovoltaic panel and thermoelectric generator, compared to simulations without the heat pipe. However, the simulations show that the power of the thermoelectric generator is still low. In addition, the simulations show the impact of contact resistances (RTC) on the temperature and power generation of CubeSat. Instituição: Universidade Federal do Maranhão Tipo do documento: Dissertação 2023-02-28T00:00:00Z https://tedebc.ufma.br/jspui/handle/tede/5458 Título: SIMULAÇÃO DO PROCESSO DE GASEIFICAÇÃO VIA CFD VISANDO A PRODUÇÃO DE BIOQUEROSENE PARA O SETOR AEROESPACIAL Autor: SANTOS, Fernanda Hellen de Souza Primeiro orientador: BARRADAS FILHO, Alex Oliveira Abstract: The use of biomass as a biofuel source has grown in recent decades as a sustainable alternative to petroleum-derived products, including aviation kerosene (AVK). Biofuels offer an option to mitigate greenhouse gas emissions, responsible for climate changes. In this study, the process of biomass conversion through gasification in a fluidized bed reactor was investigated. ANSYS FLUENT 2022 R2 was employed to simulate a gasifier, considering the presence of a gas phase and a particulate phase (composed of biomass and sand), using the Eulerian approach and Granular Kinetic Theory. The computational model was constructed by utilizing the kinetics described in Nunn et al.'s work (1985) through the creation of a User-Defined Function (UDF) compiled in ANSYS FLUENT. The mesh test was conducted based on the works of Taghipuor et al. (2005) and Sant'Anna et al. (2017). The results of the mesh test indicated that Mesh 2 was selected due to its superior quality parameters. Within the chemical kinetics, the influence of temperatures (800, 973, and 1200 K) on the compositional concentrations of synthesis gases (CO, CO2, H2, and CH4) was analyzed. In the simulation of the mathematical model for the biomass pyrolysis process, the results showcased the final composition of gas production, tar (0,493%), and char (0,090%). At the simulation temperature of 973 K, thermal cracking of the light tar gases occurs, ensuring better perfomance of the gasification process. Instituição: Universidade Federal do Maranhão Tipo do documento: Dissertação 2023-10-16T00:00:00Z https://tedebc.ufma.br/jspui/handle/tede/5208 Título: Simulação térmica e geração de energia de um CubeSat Autor: SANTANA, André Luís Rodrigues Primeiro orientador: SOUZA, Francisco Das Chagas de Abstract: CubeSat is a standard satellite based on the dimensions of a cube with 10 × 10 × 10 cm, about which academia and industry have already carried out several successful missions in the last decade and still have significant growth potential in the coming years. In space, these small satellites must survive in the vacuum environment, with intense temperature variation and thermal gradient, usually above 60◦C and, in a few minutes, below -30◦C. One of the critical subsystems of CubeSat is thermal control, which maintains temperature stability between the operational bands of the subsystems. Another equally critical subsystem is the power system, responsible for generating electrical energy used during the orbit. This dissertation focuses on the thermal and power simulation of a typical CubeSat 1U. The heat transfer simulation is divided between the irradiance and thermal models. The irradiance model determines the magnitude of heat sources, which are made up of solar radiation, albedo, and infrared emission from the earth; such sources depend on the attitude model (Pointing of CubeSat), orbit (orbital dynamics), and altitude (vertical distance). From the variation of the model, different thermal scenarios faced by CubeSat along the orbit are investigated. Then, to investigate heat transfer in space, a thermal model based on the Finite Volumes Method (FVM) is structured, using the irradiance model as a contour condition on the external surfaces of the solar panel. In total, five orbits are simulated: maximum solar exposure with eclipse (MES-0), maximum sun exposure without eclipse (MES-90), detumbling with eclipse (DET-0), detumbling without eclipse (DET-90), and maximum exposure to the eclipse coupled to a heat tube (MES-0-HP). In addition, recognizing that heat is an energy source, this work simulates a thermoelectric generator (TEG) coupled to the CubeSat, evaluating the potential of TEG for power generation. The results indicate that the different scenarios of the orbit impact the power generation and thermal control of CubeSat, being essential to predict the thermal conditions for the design of small satellites. During thermal simulations, a heat tube (HP) between solar panels is considered in the model, improving the power generation and performance of the photovoltaic panel and thermoelectric generator, compared to simulations without the heat pipe. However, the simulations show that the power of the thermoelectric generator is still low. In addition, the simulations show the impact of contact resistances (RTC) on the temperature and power generation of CubeSat. Instituição: Universidade Federal do Maranhão Tipo do documento: Dissertação 2023-02-28T00:00:00Z