Submitted by Verena Pereira (verenagoncalves@uefs.br) on 2017-02-17T22:06:12Z No. of bitstreams: 1 Disserta??o Final (Corre??es) - Eduardo Mendes.pdf: 20884254 bytes, checksum: 2f9c97501da8a0259ee7afa7dee7506d (MD5) / Made available in DSpace on 2017-02-17T22:06:12Z (GMT). No. of bitstreams: 1 Disserta??o Final (Corre??es) - Eduardo Mendes.pdf: 20884254 bytes, checksum: 2f9c97501da8a0259ee7afa7dee7506d (MD5) Previous issue date: 2016-08-25 / In this research we studied evasive maneuvers to avoid collisions in an environment with debris, enabling missions to the space. When a collision occurs, usually the space vehicle is completely damaged and destroyed, thus ensuring that the satellite avoids this collision will preserve the objective of the mission. In this study, we will see how a space vehicle can perform an evasive maneuver through thedriveline under the effect of the atmospheric drag force, whose efficiency will be established through the settings of technological parameters, which are the amount of fuel in the space vehicle and the ability to eject the propellant through the propulsion system. The purpose of the evasive maneuver is to avoid the collision but to keep the vehicle in its nominal orbit. At first we found several initial conditions of collision with the space vehicle under the influence of Earth's gravitational force, to ensure that there would be a collision between objects, from that on, the propulsion force was applied, after that, considering only the effect of atmospheric drag on the objects and right after the two collisional objects were brought under the effect of both forces, the force of the atmospheric drag and the propulsion together. In search of the most economical maneuver, from the point of view of fuel consumption, maneuvers were performed with lower propulsion drive time, and at different times of the trajectory of the vehicle and also at random times with the use of the propulsion force . The maneuvers were found through numerical simulations for each mathematical model of disturbances added to the orbital dynamics under the influence of the gravitational force. / Neste trabalho, fizemos o estudo de manobras evasivas para evitar colis?es em ambiente de detritos, viabilizando as miss?es espaciais. Quando ocorre uma colis?o, normalmente o ve?culo espacial fica totalmente danificado e destru?do, portanto, garantir ao sat?lite o desvio da colis?o, preservar? o objetivo da miss?o. Neste estudo, veremos como um ve?culo espacial pode executar uma manobra evasiva, atrav?s do sistema propulsor, sob o efeito da for?a de arrasto atmosf?rico, cuja efici?ncia ser? estabelecida atrav?s das configura??es dos par?metros tecnol?gicos, sendo estes, a quantidade de combust?vel do ve?culo espacial e a capacidade de ejetar propelente pelo sistema propulsor. O objetivo da manobra evasiva ? evitar a colis?o, mas, mantendo o ve?culo em sua ?rbita nominal. A princ?pio foi encontrado um conjunto de condi??es iniciais de colis?o com o ve?culo espacial sob o efeito da for?a gravitacional da Terra, para garantir que haveria a colis?o entre os objetos e, a partir disto, foi aplicada a for?a de propuls?o, depois considerando somente o efeito do arrasto atmosf?rico sobre os objetos e logo ap?s, o ve?culo espacial e o detrito foram postos sob o efeito de ambas da for?a de propuls?o e do arrasto atmosf?rico, juntas. Em busca da manobra mais econ?mica, do ponto de vista do consumo de combust?vel, foram executadas manobras com tempo de acionamento de propuls?o menor, e em diferentes momentos da trajet?ria do ve?culo e tamb?m por tempos aleat?rios de acionamento de for?a de propuls?o. As manobras foram determinadas atrav?s de simula??es num?ricas para cada modelo matem?tico das perturba??es adicionadas ? din?mica orbital sob o efeito da for?a gravitacional.

Submitted by Verena Pereira (verenagoncalves@uefs.br) on 2018-11-14T22:49:02Z No. of bitstreams: 1 Disserta??o de Jadiane(C).pdf: 1600835 bytes, checksum: 6b3162236247731029b8ced5d94cc873 (MD5) / Made available in DSpace on 2018-11-14T22:49:02Z (GMT). No. of bitstreams: 1 Disserta??o de Jadiane(C).pdf: 1600835 bytes, checksum: 6b3162236247731029b8ced5d94cc873 (MD5) Previous issue date: 2018-07-07 / Earth's operational orbiting satellites are very useful for space science because it has great features as these services enable research and space explorations for scientific, commercial, and military interests as well. However, the increasing flow of space activities has increased the amount of debris orbiting in the operating regions, thereby increasing the chances of collisions in those areas, and allowing immeasurable damages if the satellite remains in this collision orbit. In view of the large number of operational objects, the study of evasive maneuvers for space vehicles has been growing, and this one is important in face of the possibility of collisions, not only with a single debris but with clouds of space debris. The objective of the evasive maneuver is to avoid collision, but by keeping the vehicle in its orbit nominally. The history of the phenomenon, that is, how it evolves over time, is found when the differential equation that represents the phenomenon is solved. From the point of view of Physics and Mathematics, the more realistic the model, the more difficult is the solution of the differential equations representing the phenomenon. Thus, this work seeks to present the analytical and semi-analytical solutions for the equations describing the relative dynamics between two bodies subjected to gravitational force, Chohessy-Wiltshire equations, under the influence of forces: gravitational, atmospheric drag, chemical propulsion ( exponential model and linear model), atmospheric drag plus chemical propulsion and plasma propulsion, and finally present their respective computational simulations. These simulations made it possible to show what happens to the operational satellites against a collision, for each specified model. With the contribution of the development of the atmospheric drag equation, with the drag coefficient varying / Os sat?lites operacionais em ?rbita da Terra s?o muito ?teis para a Ci?ncia Espacial, pois possuem grandes aplica??es e fun??es. Seus servi?os possibilitam pesquisas e explora??es espaciais para interesses cient?ficos, comerciais e tamb?m militares. Por?m, o crescente fluxo das atividades espaciais tem elevado a quantidade de detritos orbitando nas regi?es operacionais e, desse modo, aumentando as chances de colis?es nessas ?reas, e possibilitando imensur?veis preju?zos, caso o sat?lite permane?a nessa ?rbita de colis?o. Diante da grande quantidade de objetos operacionais e n?o operacionais, o estudo de manobras evasivas para os ve?culos espaciais torna-se urgente e necess?rio, visto a possibilidade de colis?es, n?o s? com um ?nico detrito, mas com nuvens de detritos espaciais. O objetivo da manobra evasiva ? evitar a colis?o, mas, mantendo o ve?culo em sua ?rbita nominal. A hist?ria do fen?meno, ou seja, como ele evolui no tempo, ? encontrada quando a equa??o diferencial que o representa ? resolvida. Assim obtemos a posi??o relativa entre os objetos colisionais no tempo. Do ponto de vista da F?sica e da Matem?tica, quanto mais realista for o modelo, mais dif?cil ser? a solu??o das equa??es diferenciais representantes do fen?meno. Assim, este trabalho busca apresentar as solu??es anal?ticas e semi-anal?tica para as equa??es que descrevem a din?mica relativa entre dois corpos sob a atua??o das for?as: gravitacional, de arrasto atmosf?rico, propuls?o qu?mica (modelo exponencial e modelo linear) e propuls?o plasma. Por fim, busca apresentar suas respectivas simula??es computacionais. Estas simula??es possibilitaram mostrar o que acontece com os sat?lites operacionais frente ? uma colis?o, para cada um modelo especificado. Outra contribui??o deste trabalho ? solu??o semi-anal?tica da din?mica relativa com arrasto atmosf?rico para densidade atmosf?rica n?o constante

The thesis deals with the terminology used in forensic engineering practice at the analysis of road accidents. It means defining the concepts describing specific expert research in the area of car accident analysis such as the option of evasive action and the possibility of preventing collision. Further on, the thesis focuses on the terminology used in areas closely related to analysis of road accidents namely dealing with cases of criminal activities in the field of motor vehicle insurance from an expert point of view. In this area, terms such as extent of the damage, character of the damage, correspondence of the damage and the technical acceptability of accident, are solved. These terms constitute a formal process that can serve as a tool for experts when dealing with such cases. In addition, selected terms from the technical-legal area, which the experts often encounter, are processed here. At the same time, there is no uniform approach to their evaluation from a technical perspective. Here, there is a possibility of setting the limits of a sudden change of speed and a sudden change of direction.