Made available in DSpace on 2014-10-09T12:28:10Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:44Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:44:36Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:07Z (GMT). No. of bitstreams: 1 07009.pdf: 4378283 bytes, checksum: 79cafd4e124d9349d8fbb819d59b5959 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:28:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:14Z (GMT). No. of bitstreams: 0 / As câmaras de ionização tipo lápis são utilizadas para dosimetria de feixes em equipamentos de tomografia computadorizada (CT). Neste estudo foi estabelecida uma nova metodologia de calibração destas câmaras, visando a adequação do Laboratório de Calibração de Instrumentos do Instituto de Pesquisas Energéticas e Nucleares (LCI) aos atuais padrões metrológicos internacionais que tratam dos procedimentos específicos para calibração das câmaras utilizadas em CT. Primeiramente partiu-se da implantação das novas qualidades de radiação padrão RQT, que simulam feixes não atenuados usados para aplicações em CT, de acordo com a IEC 61267 da International Electrotechnical Commission (IEC). Após o estabelecimento dos campos padrões de radiação, foi implantada a metodologia de calibração específica para câmaras lápis segundo o Technical Report Series No. 457, da International Atomic Energy Agency (IAEA), que descreve as particularidades do procedimento a ser seguido pelos Laboratórios de Dosimetria Padrão Secundário (SSDLs) em termos de colimação e posicionamento em relação ao feixe de radiação. Inicialmente, foram realizadas medições de PPV (kV) e determinação das filtrações adicionais de cobre por meio dos valores de camada semi-redutora (CSR) recomendados pela norma IEC 61267, para que as qualidades de radiação de referência: RQT 8, RQT 9 e RQT 10 fossem implantadas. Para os filtros adicionais, foram utilizados alumínio e cobre de alta pureza (maior ou igual a 99,9%). Uma metodologia alternativa para determinar as filtrações adicionais também foi utilizada, através da qual se encontrou diretamente as RQTs em espessuras de filtros de cobre equivalente ao conjunto RQR (Al) + Filtração Adicional (Cu), sendo esta uma opção quando não se têm implantadas as RQRs. Com a implantação desta nova metodologia de calibração das câmaras de ionização tipo lápis, o LCI está pronto para calibrar estes instrumentos de acordo com as recentes recomendações internacionais. Permitindo assim uma melhoria na rastreabilidade das calibrações, como também na qualidade dos serviços metrológicos que o IPEN oferece para todo o País. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:28:10Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:44Z (GMT). No. of bitstreams: 0 / O objetivo desse trabalho foi estudar o comportamento do principal equipamento de raios X utilizado nos procedimentos do laboratório de calibração do IPEN, LCI, operado nos intervalos de tensão de 25 a 150 kV utilizando os medidores de tensão não invasivos DiavoltTM da PTW e do sistema de espectrometria ORTEC, modelo NOMAD-PLUS 92X para o estabelecimento de um programa de controle de qualidade. O medidor Diavolt foi utilizado para as medições de kerma no ar, tensão de pico e tensão de pico prático. As medições foram feitas variando parâmetros como, corrente elétrica, Qualidade de Radiação X para Radiodiag-nóstico, angulação do medidor e sua distância em relação ao ponto focal do aparelho de raios X. Os resultados encontrados foram comparados com dados encontrados na literatura. Com o sistema de espectrometria, foram gerados os espectros com a finalidade de determinar as tensões de pico relativas às tensões nominais escolhidas e caracterizar as Qualidades em Radiodiagnóstico determinadas anteriormente. O programa de controle de qualidade estabelecido possibilita o controle do funcionamento tanto dos instrumentos de medição (câmaras de ionização, medidor de tensão e corrente e espectrômetro), bem como do sistema de radiação X. Neste trabalho também foi sugerida a periodicidade de realização de cada um dos testes. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Orientador: Yuzo Iano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e Computação / Made available in DSpace on 2018-08-09T14:39:29Z (GMT). No. of bitstreams: 1 Bertan_HiltonHenrique_M.pdf: 3172256 bytes, checksum: d2360855eab8586655078c1c81464461 (MD5) Previous issue date: 2007 / Resumo: Uma esfera integradora e suas propriedades foram estudadas a fim de se obter um padrão de referência em medição de potência óptica. Este trabalho apresenta pesquisas realizadas em laboratórios nacionais e internacionais. As medições com uma esfera foram comparadas com as de um medidor de potência óptica padrão de um laboratório de calibração brasileiro e com equipamentos de um laboratório de medições ópticas europeu. Os resultados indicaram que a esfera integradora em questão apresenta uma incerteza de medição menor e, portanto, pode ser usada como padrão de referência. Este trabalho também tem como finalidade mostrar que é possível elaborar um procedimento de escolha de um novo equipamento padrão utilizando-se recursos e equipamentos limitados disponíveis no laboratório / Abstract: We have studied an integrating sphere and its properties for application as a reference standard in optical power measurement. This work shows the researches made in national and international laboratories. We have compared the measurements of a sphere with the standard optical power meter of a Brazilian calibration laboratory and with equipments of a European optical measurement laboratory. The results indicate that the integrating sphere can be used as a reference standard, because its measurement uncertainty is small. This work also has the purpose to show that a procedure for the choice of new standard equipment is reliable using resources and equipment commonly available in a laboratory / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Thesis (M.Tech.:Chiropractic)-Dept. of Chiropractic, Durban Institute of Technology, 2005. / The aim of this study was to evaluate the Myofascial Diagnostic Scale, for its inter-examiner reliability and to assess its reliability and validity as an assessment tool in the diagnosis and treatment of Myofascial Pain Syndrome. / M

M.Sc. (Geology) / This study involves the quantitative analysis of fluorspar-containing slurries by two X-ray diffraction methods, whereby these two methods of on-stream analysis are compared. The first method involves a single counter with a diffracted beam monochromator, and the second method involves a fixed geometry with an incident beam monochromator. The second method is a cheaper and more robust apparatus, which can withstand the harsh environment of the flotation plants. A new algorithm was developed for a more accurate calibration method. Programmes for calibration, recalibration and measuring of unknown samples were developed. The measuring apparatus was interfaced with a microcomputer for computerised operation of the system. Results from both methods were comparable, with more accurate results obtained for the feed and tailings than for the concentrate samples. The single detector apparatus can thus be replaced by the fixed geometry model, which is less expensive and more robust.

M.Ing. / The aim of this project is to research the feasibility of an all-fibre laser distance measurement device that utilises a figure-eight fibre laser (F8L), in the nonlinear amplifying loop mirror (NALM) configuration, as a light source and implements pulse compression to improve the accuracy and signal-to-noise ratio of the system. A figure-eight fibre laser in the NALM configuration for use in a laser distance measurement device is described. The theory of fibre lasers is discussed, including mode-locking and Qswitching, and the characteristics of a NALM loop are analysed. By varying the length of the NALM loop from 500 m to 2000 m or inserting highly nonlinear dispersion shifted fibre, a variety of pulses in the picosecond to nanosecond range can be produced. The lengths of the pulses depend on the length of the NALM loop, the pump power and the setting of the polarisation controllers. The figure-eight fibre laser is pumped with a 980 nm laser diode up to 550 mA, which corresponds to 320 mW. Distance measurements are done with short unmodulated and long modulated pulses. Distance measurement with short unmodulated pulses is discussed only briefly and tested with a simple experiment. The focus of this project is distance measurement with long modulated pulses. A low autocorrelated binary sequence is modulated onto one of the long pulses produced by the figure-eight fibre laser by an electro-optic amplitude modulator. The long pulse gives the proposed system a good signal-to-noise ratio (SNR), while the modulation improves the accuracy. A Barker code of length 13 is proposed as modulation code because of its good autocorrelation properties. The Barker code will improve the accuracy 13-fold, with a corresponding increase in SNR. An electro-optic amplitude modulator is used to implement the modulation. The modulated long pulse is then sent to a target. After reflection, the signal is detected and cross-correlated to obtain the time-of-flight for the pulse. The code generation and cross-correlation are implemented with an FPGA via VHDL programming. The distance to a target can be calculated by knowing the time-of-flight and the speed of light in the propagation medium. In this project the resolution, single-shot precision, accuracy, linearity, repeatability and maximum unambiguous distance of the proposed all-fibre laser distance measurement device are examined.

Three systematic instrumental errors exist in electronic distance measuring instruments (EDMI): 1) scale error, 2) constant offset error, and 3) cyclic error. The potential magnitude of these errors requires that each EDMI should be calibrated for all three errors. The calibration constants of EDMI may be monitored on an arbitrary base line; however, a calibrated base line is required to perform an accurate EDMI calibration for constant offset and scale errors. Calibration of cyclic error requires monumentation not normally found on a calibration base line. Cyclic error can be measured on a short base line in the laboratory. The surveyors in the State of Virginia would benefit from a statewide network of calibrated base lines. A network covering the state would provide convenient access for the state's surveyors. A unified network of base lines would give the states surveyors a standard of comparison for their EDMI. This standard of comparison would be nationwide if Virginia would choose the National Geodetic Survey (NGS) to calibrate the base lines in its network. Base line calibration by NGS would require that the state abide by NGS specifications for establishing its base line network. / M.S.

A mechanical, non-contact soil profile meter was developed to measure soil elevations before and after an artificial rainfall for erosion studies. The design goals were to measure the heights of the soil in a 1.5 x 1.5 m bin with an accuracy of ±1.0 mm and at a data collection rate of 2 points per second. The profiler consisted of a laser and a digital camera for height measurements, and a drive system for horizontal movement. The device was calibrated to determine the accuracy of horizontal positioning and the error associated with the height measurements. The positioning accuracy of the profiler was ±0.12 mm and the calibrated height error was ±0.68 mm. The rate of data collection was 32 points per minute. The calibrated height measurement unit was tested with actual soil samples. The analysis of the data collected from 9 different soil colors at 3 different heights and 5 different locations along the profiler indicated that color, rod deflection, and vertical distance between the lens and the surface affected the height measurements. The error for absolute heights was 1.2 mm and the error for the difference in heights was 0.2 mm. The outdoor performance of the profiler was also checked and the result was satisfactory. / M.S.