Thesis (Ph.D.)--University of Central Florida, 2008. / Advisers: Piotr Mikusiński, Dragu Atanasiu. Includes bibliographical references (p. 77-78).

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references (leaves 120-123). Also available in an electronic version.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 140-143).

Made available in DSpace on 2014-06-11T19:25:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-10-26Bitstream added on 2014-06-13T20:14:07Z : No. of bitstreams: 1 salomao_lr_me_rcla.pdf: 917808 bytes, checksum: d44faa6f545a9927fe555baaacdcc99c (MD5) / Este trabalho pode ser separado em duas partes. Na primeira apresentamos, de forma resumida, a natureza fractal das séries de precipitação de chuvas, a estimativa do expoente de Hurst (H), a transformada wavelet, o seu uso na estimativa de H e a comprovação, por meio de testes com séries de movimento browniano fracionário geradas com H estabelecido a priori, que temos um bom método para estimar H com a transformada wavelet. Na segunda parte é feita uma análise das séries temporais de precipitação de chuvas (séries de chuva). As séries de chuvas foram obtidas junto ao Departamento de Águas e Energia Elétrica (DAEE) do estado de São Paulo e são constituídas de medições diárias, em milímetros, da quantidade de chuva em postos meteorológicos distribuídos em todo o estado. Algumas séries apresentam ausências de medições que acabam transformando uma série longa em duas ou mais séries menores. Em função disso foi estabelecido um procedimento que permite aproveitar essas séries com ausências (dias sem medições) para estimar o expoente de Hurst. A partir de considerações climáticas o estado foi dividido em nove regiões. Foram selecionadas séries com 20 anos de registros de chuva (de janeiro de 1978 a dezembro de 1997). Dos valores de H encontrados foi feita uma média para cada região climática do estado de São Paulo. / This work can be separated into two parts. In the first part is briefly presented the fractal nature of the rain precipitation series, the estimate of the Hurst exponent (H), the wavelet transform, its use in the estimate of H and the evidence, by tests with generated series of fractional brownian motion with H established a priori, that we have a good method to estimate H with wavelet transform. In the second part an analysis of rain precipitation series is made. The rain series had been obtained from the Departmento de Águas e Energia Elétrica (DAEE) of the state of São Paulo and contain daily measurements, in milimeters, of the amount of rain in distributed meteorological stations all over the state. Some series present absences of measurements, transforming a long series into two or more lesser series. A procedure was established, allowing to use these series with absences (days with no measurements) to estimate the Hurst exponent. From climatic considerations the state was divided into nine regions. The regions with rain data over a period of 20 years have been selected as rain series (from january 1978 to december 1997). From the several values of H, we computed an averaged value of H for each climatic regions of the state of São Paulo.

No description available.

The adaptation of a general purpose laboratory minicomputer for nuclear medicine imaging is described. Electronic interfaces have been designed and constructed to link nucleonic equipment to a PDP 12 computer. A computer television display system has been developed to facilitate interactive processing of scintigraphic data. The main features of the television system are that it is relatively inexpensive and reliable. A domestic quality receiver has been adapted for use as a colour monitor. Any instrument that records data will produce a distorted or degraded version of the input signal. Generally, imaging equipment will produce a blurred image of the object, and in the case of scintigraphic imaging the blurs may be comparable to the size of the physiological structures being investigated. The process of refocussing the recorded data is called, in mathematical terms, deconvolution. In this study Fourier transform techniques have been developed as methods of implementing deconvolution. It is shown that the restoration of images in the presence of noise is likely to be a mathematically unstable process. Four methods of accommodating the problems associated with noise are described. Each method has built in optimisation of one form or another so that mathematically stable algorithms are used to implement deconvolution. This means that all the parameters used by the computer programs are determined automatically so that the computer operator is not required to select any parameters manually. A brief description of two dimensional digital filtering is given to enable comparison between filtering and deconvolution of scintigrams. A two dimensional lowpass filter is developed which automatically defines the passband frequency response appropriate to a particular scintigram. Finally, all the signal processing methods are tested on both simulated and clinical data. Results show that deconvolution offers advantages over digital filtering particularly for scintigrams obtained from morphic structures. Some of the problems of deconvolving certain types of scintigram are discussed.

On-line induction machine condition monitoring techniques have been used widely in the detection of motor broken rotor bars for decades. Research has found that when broken bars occur in the machine rotor, the anomaly of electromagnetic field in the air gap will cause two sideband frequency components presenting in the stator current spectrum. Therefore, identification of these sideband frequencies can be used as a convenient and reliable approach to broken rotor bar fault diagnosis. Discrete Fourier Transform (DFT) is a conventional spectral analysis method used in this application. However, the use of DFT has several limitations. The most important one among them is the restriction of frequency resolution by window length. Due to this limitation, the accuracy of broken rotor bar detection can be highly affected in cases such as light machine load and limited data records. However, Prony's method for spectral analysis has the ability of overcoming the restriction of data window length on the frequency resolution, from which the DFT suffers. Such feature makes Prony's method a promising choice for broken rotor bar diagnosis when the machine is operating under light or varying load, or when only restricted data is available. In this thesis, I have demonstrated the implementation of this technique in the induction motor broken rotor bar detection, revealed its better performance than DFT in terms of maintaining high resolution in frequency domain whilst using a much shorter window, and analyzed the influential factors to the method of Prony Analysis (PA). In this thesis, an induction machine model that includes broken rotor bars is developed using Matlab/Simulink and verified by comparing the experimental and the simulated results. The Prony Analysis method for broken bar diagnosis is implemented and tested using both simulated and measured stator current data. Comparisons between PA and DFT results are presented, clearly indicating improvements of broken bar diagnostics using PA. / Thesis (M.Eng.Sc.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2008

University of Macau / Faculty of Science and Technology / Department of Mathematics

Thesis (M.S.)--Brigham Young University. Dept. of Computer Science, 2003. / Includes bibliographical references (p. 120-130).