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  • Caracterização Fitoquímica da Phyllanthus welwitschianus Mull. Arg.
    Publication . Dala, Cidália António Faila Watxitomba; Mendonça, Dina Isabel Malheiros Dinis de
    As plantas medicinais são o recurso de saúde mais acessível e disponível para grande parte das comunidades no mundo, principalmente em África onde a rede de saúde é bastante deficiente. A presente investigação centra-se na identificação de compostos químicos da planta Phyllanthus welwitschianus. As folhas da planta com que se fez o estudo, foram recolhidas na localidade da Umpata, província da Huila em Angola, onde a população utilizam-nas para tratamento de feridas. O material vegetal foi macerado e exaustivamente extraído à temperatura ambiente com metanol, posteriormente procedeu-se ao fracionamento de uma amostra do extrato de metanol. Essa amostra foi fracionada com mistura de vários solventes de polaridades crescentes, resultando em dez frações, das quais, em três delas isolaram-se três compostos: tetracos-1-eno, ß-sitosterol e sacarose. O tetracos-1-eno foi isolado a partir da fração hexano/acetato de etilo 9:1, o ß-sitosterol foi isolado a partir da fração hexano/acetato de etilo 1:1, e a sacarose isolada a partir da fração de acetato etilo/metanol 1:1, os compostos foram caracterizados por métodos espectroscópicos de IV, RMN 1D e 2D. Estes resultados foram comparados com os referenciados na bibliografia, confirmando que os compostos ß-sitosterol e sacarose, já tinham sido identificados no mesmo género.
    2019-04-04Master thesis Open access Show more
  • Preliminary topology optimization of small unmanned aircraft wings for additive manufacturing
    Publication . Miguel, Cátia Alexandra Louro; Gamboa, Pedro Vieira
    Additive Manufacturing (AM) describes the processes which produce 3D parts, being these manufactured through a layer-by-layer procedure. The AM technology takes a wide variety of materials, so there is not a barrier in that field when a project is proposed. It also allows the part production in less time, reducing the costs and material waste. Topology Optimization combines the finite element method with mathematical optimization formulas, providing a better material distribution in the reference domain of the geometry under analysis. This optimization can be applied to improve the performance of existing products or to create new ones. By combining these two tools, AM and topology optimization, create lighter structures with greater rigidity and complexity is possible. Which previously was not possible due to the limitation in tools and molds of traditional methods. This work searches the possibility of using topology optimization as a tool to obtain a lighter wing to an unmanned aerial vehicle (UAV). The objective is to investigate the stiffness and strength characteristics of a wing, being presented in different cases for analysis. This dissertation describes the designs and numerical procedures, in which are included computation fluid dynamics, structural analysis, and topology optimization. The optimization was realized with the aim of minimizing mass. The entire numerical procedure was performed in ANSYS software. In this work, there is a study case which was evidencing, due to the 74% of weight reduction, but for the aircraft requirements in the study, more investigations are necessary, since the final design wing has, approximately, 1.5kg and the UAV should have a mass of 5kg.
    2019-04-04Master thesis Open access Show more