The identification of known asteroids on existing CCD pictures would allow us to obtain accurate astrometric and photometric asteroid properties. Some asteroids might have ambiguous orbital elements, thus their identification along with their exact positions on multiple picture frames could significantly improve their orbital elements. Furthermore, the possibility of identifying known asteroids on older pictures, sometimes preceding their discovery date, might allow the study of non-gravitational effects like the Yarkovsky effect. Identifying a potential Yarkovsky effect on asteroids is challenging because it is extremely weak. However, this effect cumulates with time, therefore, it is necessary to find astronomical pictures that are as old as possible. In addition, we need to collect high quality CCD pictures and use a methodology that would allow obtaining a statistically significant sample of asteroids. To accomplish this, we decided to use the online archive of the Subaru telescope at Mauna Kea Hawaii because it has a prime-focus camera with a very high resolution of 80 millions pixels very well suited to capture serendipitous asteroids. In addition, the Subaru online archive has pictures from the last 10 years. iv The methodology used in this thesis is to build a database that contains the orbital elements of all the known asteroids, allowing us to write a program that calculates the approximate position of all the asteroids at the date and time of each CCD picture we collect. To obtain a more precise position, the program also interfaces the JPL NASA Horizons on-line computation service. Every time an asteroid is found on a picture, Horizons sends its theoretical location back to the program. A later visual identification of this asteroid at this theoretical location on the picture triggers its input into our sample for further study. This method allowed us to visually confirm 508 distinct asteroids on 692 frames with an average diameter of 3.6 km. Finally, we use the theory (given in appendix A) to calculate the theoretical drift of these asteroids that we compare with the one we measured on the CCD pictures.

A crescente exigência do setor automotivo por maior produtividade com redução de custos, aliada aos novos materiais que compõe as carrocerias e seus revestimentos, levou ao estudo da correlação da resistência dinâmica, força de expansão térmica e indentação, com a formação do ponto de solda, a fim de qualificar e controlar a soldagem por resistência a ponto. Para o estudo ter validade prática a qualificação da solda, os parâmetros de soldagem e corpos de prova foram definidos conforme norma AWS-SAE D8-9M 2002. Os corpos de prova para os ensaios foram retirados das chapas que compõe uma carroceria veicular. O cabeçote de soldagem foi projetado e construído seguindo os padrões de máquinas industriais. Os instrumentos de medição foram desenvolvidos especificamente para atender as condições industriais da soldagem por resistência. Os ensaios simularam as variações de parâmetros e produção dos pontos de solda conforme ocorre na indústria automobilística. As análises foram realizadas através da comparação gráfica e matemática do comportamento das grandezas medidas com a qualificação dimensional do ponto. A correlação, apresentada, distingue chapas de espessuras diferentes, materiais de revestimento, variação de parâmetros, erros de posicionamento (ponto torto), expulsão de material (flash), variações na formação do ponto (undersize) e o mais importante, desgaste dos eletrodos. Esta correlação permite criar um sistema de qualificação e controle do ponto de solda. / The growing demand from the automotive sector for greater productivity, reduced costs, combined with new materials that make up their bodies and coats, led to the study of the correlation of the dynamic resistance, thermal force expansion and indentation, with the formation of the spot weld, in order to qualify and control the resistance spot welding. For the study to be valid practicing the qualification of spot weld, welding parameters and specimens were define according AWS - 9M SAE D8 2002 standard. The specimens for testing were removed from the sheets that make up a vehicle body. The welding head was designed and built according the standards of industrial machinery. Measuring instruments were developed specifically to meet the conditions of industrial resistance welding. The tests simulated the variations of parameters and production of welding spots as occurs in automotive industry. The analyzes were performed through the graphical comparison and mathematical behavior of measured quantities with dimensional spot qualification. The correlation presented distinguishes sheets of different thicknesses, coating materials, variation of parameters, positioning errors (crooked point), expulsion of material (flash), variations in spot formation (undersize) and most important, wear of the electrodes. This correlation allows to create a system of qualification and control of the spot welding.

A crescente exigência do setor automotivo por maior produtividade com redução de custos, aliada aos novos materiais que compõe as carrocerias e seus revestimentos, levou ao estudo da correlação da resistência dinâmica, força de expansão térmica e indentação, com a formação do ponto de solda, a fim de qualificar e controlar a soldagem por resistência a ponto. Para o estudo ter validade prática a qualificação da solda, os parâmetros de soldagem e corpos de prova foram definidos conforme norma AWS-SAE D8-9M 2002. Os corpos de prova para os ensaios foram retirados das chapas que compõe uma carroceria veicular. O cabeçote de soldagem foi projetado e construído seguindo os padrões de máquinas industriais. Os instrumentos de medição foram desenvolvidos especificamente para atender as condições industriais da soldagem por resistência. Os ensaios simularam as variações de parâmetros e produção dos pontos de solda conforme ocorre na indústria automobilística. As análises foram realizadas através da comparação gráfica e matemática do comportamento das grandezas medidas com a qualificação dimensional do ponto. A correlação, apresentada, distingue chapas de espessuras diferentes, materiais de revestimento, variação de parâmetros, erros de posicionamento (ponto torto), expulsão de material (flash), variações na formação do ponto (undersize) e o mais importante, desgaste dos eletrodos. Esta correlação permite criar um sistema de qualificação e controle do ponto de solda. / The growing demand from the automotive sector for greater productivity, reduced costs, combined with new materials that make up their bodies and coats, led to the study of the correlation of the dynamic resistance, thermal force expansion and indentation, with the formation of the spot weld, in order to qualify and control the resistance spot welding. For the study to be valid practicing the qualification of spot weld, welding parameters and specimens were define according AWS - 9M SAE D8 2002 standard. The specimens for testing were removed from the sheets that make up a vehicle body. The welding head was designed and built according the standards of industrial machinery. Measuring instruments were developed specifically to meet the conditions of industrial resistance welding. The tests simulated the variations of parameters and production of welding spots as occurs in automotive industry. The analyzes were performed through the graphical comparison and mathematical behavior of measured quantities with dimensional spot qualification. The correlation presented distinguishes sheets of different thicknesses, coating materials, variation of parameters, positioning errors (crooked point), expulsion of material (flash), variations in spot formation (undersize) and most important, wear of the electrodes. This correlation allows to create a system of qualification and control of the spot welding.