Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 69-75.

Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on June 8, 2009) Vita. Includes bibliographical references.

Inaug.-diss.--Halle. / Lebenslauf.

Inaug.-diss.--Leipzig. / Lebenslauf.

Published also as inaugural dissertation, Leipzig, 1887. / "Eingegangen bei der Akademie am 2. Juni 1886." Bibliographical foot-notes.

The aim of this research is to develop an accurate method for the analysis of signals composed of fluctuating harmonics. The results obtained of analysis are applied to the calibration of harmonic analysis instruments. A new method is presented suitable for the accurate analysis of smoothly fluctuating harmonic signals. The method is based on a model of signals with a known period, in which the harmonics are individually modulated by polynomial functions normalised over a sampled signal sequence time. Using this model, a decomposition method is developed such that the modulating polynomials can be recovered from a signal. The polynomial decomposition method leads to a piece-wise analysis of the waveform. Two methods based on least squares and splines respectively, are developed with the aim of giving continuity to the piece-wise analysis. Comparisons of the new method with the short time Fourier transform are given. Having defined a test signal and obtained and accurate analysis of it properties, it can be used to calibrate harmonic analysers. For a given applied signal, analysis with these devices can give rise to variation in results as a function of the phase between the signal and the STFT windows. This result distribution due to variable phase (RDVP) is discussed and examples are given for various signals. The RDVP complicates the calibration process due to the spread of results that occur when testing the device. A method is developed to find the RDVP for an applied signal that uses the polynomial decomposition method to find the modulation functions of each harmonic in the applied calibration signal. Having found the RDVP for an applied signal, it is necessary to fit the results of the analyser under test, to the distribution. The random nature of the phase makes the systematic comparison of the theoretical and measured distributions difficult to achieve. A novel method that uses multiple phase shifted modulated harmonics is presented. By comparing the results of the analyser under test to the distributions of each of the phase-shifted harmonics, a best-fit phase shift can be determined and the required calibration comparison made. Key words: time-frequency analysis, demodulation, harmonic analysis, fluctuating harmonics, waveform metrology, calibration of harmonic analysers.

We demonstrate hyperspectral imaging using two time-delayed, coherent extreme ultraviolet (XUV) sources. The approach combines broadband XUV high-harmonic generation, holographic imaging, and Fourier transform spectroscopy. The two harmonics sources are spatially separated at generation,and overlap in the far field resulting in a double slit diffraction pattern. We record the two-dimensional intensity modulation as a function of relative time delay; the Fourier transform determines the spatially dependent spectrum. To reduce the delay jitter and improve the spectral resolution, we demonstrate a novel experimental setup that records the relative delay of the two pulses through optical interference. Moreover, we have demonstrated that this broadband approach can be extended to Fourier transform holographic imaging, which avoids extensive phase retrieval computations. Applications include imaging of biological materials near the carbon K-edge.

No description available.

No description available.

In order to maintain the system reliability and minimize the impact of faults in a distribution system, a timely restoration is needed which requires accurate fault localization. Locating High Impedance Faults (HIFs) is specifically challenging because of their variable and nonlinear nature. Most existing approaches focuses on identifying the accurate fault distance occurring in the main trunk of a system, often leaving lateral branches as blind spots. To find the accurate distance to the fault in a lateral branches, a single ended fault location algorithm is proposed that uses synchronized voltage and current measurements from PMUs positioned along the trunk. Initially, a specific model that incorporates the particular characteristics of the fault is developed in the spectral domain. Subsequently, a fault location algorithm is developed that utilizes the change in a voltage of a healthy phase for calculating the accurate distance to the fault. Extensive simulations performed across different systems at different conditions proves the efficacy of the algorithm. Notably, a critical prerequisite for the algorithm's success is the presence of at least one healthy phase running parallel to the faulty phase. / Master of Science / High Impedance Faults (HIFs) in power systems often involve dangerous arcing, posing significant risks to life and property. Accurate fault location is essential to ensure timely restoration of power and mitigate hazards. While existing literature typically focuses on the location of faults in the main trunk lines, distribution systems with numerous lateral branches require precise fault distance determination in these branches for faster restoration. This study introduces a novel approach leveraging Phasor Measurement Units (PMUs) in main feeders to pinpoint fault distances in lateral branches. By analyzing voltage variations in healthy phases, the algorithm accurately determines the distance to the fault in the affected phase. Extensive testing across various systems demonstrates the algorithm's high accuracy. The presence of a healthy phase parallel to the faulty phase is essential for the working of this algorithm. This approach offers a promising solution for enhancing the accuracy of fault location in distribution systems, thereby improving outage response times.