Thesis (Ph. D.)--University of California, San Diego, 2003. / Vita. Includes bibliographical references.

Thesis (M.B.A.)--University of Hong Kong, 1981. / Also available in print.

Thesis (M.A.T.) -- School for International Training, 2006 / Advisor -- Paul Levasseur

[pt] Até há bem pouco tempo atrás, os Registradores de Perturbação utilizados em subestações de energia elétrica eram baseados em circuitos analógicos sendo a plotagem realizada através de Oscilógrafos que se utilizavam de papel foto-sensível ou gráfico. Como saída, estes equipamentos forneciam uma plotagem das formas de onda das tensões e correntes da pré-falta e da falta mas, no entanto, devido à tecnologia utilizada, não era possível se obter nem precisão das grandezas monitoradas (tensão ou corrente) nem informações sobre harmônicos presentes no sistema. Devido ao desenvolvimento de sistemas de aquisição de dados baseados em microprocessadores, novos Registradores de Perturbação (RP) têm sido desenvolvidos tendo como características: maior precisão na aquisição das grandezas; integração de funções de registros e cálculos variados; transferência de dados adquiridos via sistema de comunicação para os centros de análise; armazenamento dos dados em memória de massa (fita ou disco) para posterior manipulação matemática por computadores; sistemas de autodiagnóstico e automonitoramento para falhas em hardware e software, etc. Este trabalho se propõe apresentar alguns programas de pós- processamento que se utilizam dos dados adquiridos pelos RP, permitindo de uma forma rápida e de baixo custo informações como: tipo de falta ocorrida, componentes simétricas de seqüência positiva, negativa e zero; componentes harmônicas, a partir da análise espectral das grandezas adquiridas; localização da falta em LT`s, com indicação da distância do ponto de falta. Vários programas de teste foram desenvolvidos, além da utilização do EMTP (Electromagnectic Transient Program) e uma unidade de aquisição ARTUS para a comprovação dos algoritmos propostos. / [en] Up until recently, disturbance recorder utilized in electric energy sub-stations were based on analog circuits and the plotting was done by oscilographs that utilized photo-sensitive paper or graph paper. As a result, these instruments provided a plotting of the kinds of waves of tensions and current of the pre-fault and of the fault. However, because of the technology that was used, it was not possible to get either precision of the monitored data (tension/current) or information about harmonic elements present in the system. Due to the development of data acquisition systems based on microprocessors, new disturbance recorders have been developed with the following characteristics: greater precision in acquisition of the data; integration of the functions of registers and various calculation; transfer of acquired data to the center of analysis through a communication system; storage of data in mass memory (tape or disc) for later mathematic manipulation by computer; systems of auto-diagnosis and auto-monitoring of hardware and software failures, etc. This work presents a few programs of post-processing that utilize data acquired by the disturbance recorder providing a fast, low-cost way to get information such as: the kind of failure that occurred; symmetrical components of positive, negative and zero sequences; harmonic components from the spectral analysis of the acquired data; localization of failures on LT`S, indicating the distance of the point of failure. Several test programs were developed to prove the proposed algorythms, including the utilization of EMTP (Electromagnectic Transient Program) and a unit of acquisition ARTUS.

The purpose of this thesis is to analyze the viscoelastic properties of current large digital storage magnetic tape materials, using a custom ultra-low frequency dynamic mechanical analyzer (DMA). Through the correlated effects of frequency and temperature, the long term mechanical properties of the magnetic tape can be simulated and used for predictive analysis of long term storage quality and stability of each individual tape given applicable storage conditions. Two magnetic tapes of primary interest reviewed in this paper are both current leading high capacity tapes, one having a poly(ethylene naphthalate) or PEN substrate and the other an aromatic polyamide or ARAMID substrate. The phase angle between the two signals and the peak strain based elastic modulus (E) were then used to determine the storage modulus (E'), loss modulus (E"), and the loss tangent (tan 8). These viscoelastic characteristics of the material were determined for each individual experimental sample. The combined data was then used to create comparative plots of each sample type allowing for a more conclusive look at the magnetic tape properties under the given conditions. It is found that viscoelastic deformation, or energy loss in the material, increasingly occurs at low frequencies. These experiments also verify that viscoelastic loss also occurs due to molecular orientation and can have a large impact on results. A final comparison is also made between the two leading tape materials commonly used in industry currently by taking a direct look at relative loss in conjunction with the materials overall complex elastic modulus. This allows a more definitive strength comparison of the defined materials · under given conditions.

No description available.

Modern aircraft are capable of recording hundreds of parameters during flight. This fact not only facilitates the investigation of an accident or a serious incident, but also provides the opportunity to use the recorded data to predict future aircraft behavior. It is believed that, by analyzing the recorded data, one can identify precursors to hazardous behavior and develop procedures to mitigate the problems before they actually occur. Because of the enormous amount of data collected during each flight, it becomes necessary to identify the segments of data that contain useful information. The objective is to distinguish between typical data points, that are present in the majority of flights, and unusual data points that can be only found in a few flights. The distinction between typical and unusual data points is achieved by using classification procedures. In this dissertation, the application of classification procedures to flight data is investigated. It is proposed to use a Bayesian classifier that tries to identify the flight from which a particular data point came. If the flight from which the data point came is identified with a high level of confidence, then the conclusion that the data point is unusual within the investigated flights can be made. The Bayesian classifier uses the overall and conditional probability density functions together with a priori probabilities to make a decision. Estimating probability density functions is a difficult task in multiple dimensions. Because many of the recorded signals (features) are redundant or highly correlated or are very similar in every flight, feature selection techniques are applied to identify those signals that contain the most discriminatory power. In the limited amount of data available to this research, twenty five features were identified as the set exhibiting the best discriminatory power. Additionally, the number of signals is reduced by applying feature generation techniques to similar signals. To make the approach applicable in practice, when many flights are considered, a very efficient and fast sequential data clustering algorithm is proposed. The order in which the samples are presented to the algorithm is fixed according to the probability density function value. Accuracy and reduction level are controlled using two scalar parameters: a distance threshold value and a maximum compactness factor. / Ph. D.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / For many years VME has been the platform of choice for high-performance, real-time data acquisition systems. VME’s longevity has been made possible in part by timely enhancements which have expanded system bandwidth and allowed systems to support ever increasing throughput. One of the most recent ANSI-standard extensions of the VME specification defines RACEway, a system of dynamically switched, 160 Mbyte/second board-to-board interconnects. In typical systems RACEway increases the internal bandwidth of a VME system by an order of magnitude. Since this bandwidth is both scaleable and deterministic, it is particularly well suited to high-performance, real-time systems. The potential of RACEway for very high-performance (200 Mbps to 1 Gbps) real-time systems has been recognized by both the VME industry and a growing number of system integrators. This recognition has yielded many new RACEway-ready VME products from more than a dozen vendors. In fact many significant real-time data acquisition systems that consist entirely of commercial-off-the-shelf (COTS) RACEway products are being developed and fielded today. This paper provides an overview of RACEway technology, identifies the types of RACEway equipment currently available, discusses how RACEway can be applied in high-performance data acquisition systems, and briefly describes two systems that acquiring and capturing real-time data streams at rates from 200 Mbps to 1 Gbps using RACEway.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2008. / A rapid measurement system is implemented using two digital video cameras, presenting a faster and less expensive solution to certain metrology problems. The cameras are calibrated from one stereo image-pair of a 3D calibration grid that allows an immediate assessment of the achievable metric accuracy of the system. Three different methods, using either laser tracking or structured light patterns, were developed and employed to solve the coordinate extraction and correspondence matching problems. Different image processing techniques were used to speed up the entire measurement process. All software development was accomplished using only freely distributed software packages. The system achieves calibration in less than a minute and accumulates point correspondences at 12 frames per second. Accuracies of greater than 0.4 mm are achieved for a 235 x 190 x 95 mm measurement volume using a single pair of images with 640 x 480 pixel resolution each.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / For the last 30 years Magnetic Tape Systems have been the primary means of recording data from airborne instrumentation systems. Increasing data rates and harsh environmental requirements have often exceeded the ability of tape-based systems to keep pace with technology. Throughout this time data recordings have been made mostly with analog longitudinal systems and most recently with digital recording systems that record on commercial DLT, and super VHS tape media. The recordings are played back with the same type of tape device allowing for the data to be processed and/or archived. Since not all data reduction facilities can process the same type of tape media, often tapes are dubbed from one type of tape media format to another, corrupting the translated data. This paper examines operational and data reduction benefits, and life cycle cost of Solid State Recorders as a replacement for existing airborne tape recorders.