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Typescript (photocopy). / Digitized by Kansas Correctional Industries

by W.G. Tuller, W.C. Galloway and F.P. Zaffarano. / "November 20, 1947." / Includes bibliographical references. / Army Signal Corps Contract No. W-36-039 sc-32037.

Thesis (M. Eng. Sc.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (Ph.D.)--University of Western Australia, 2007.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [99]-104).

A power system should always operate in a balanced and stable condition at its designed frequency. Any significant upset of this balance will produce a change in the power system frequency. It is the responsibility of the monitoring and protective devices to detect and restore the system to the equilibrium operating condition at the nominal frequency as soon as it is practical to do so. An accurate measurement of both frequency deviation and rate of change of frequency will greatly facilitate the restoration process. In this thesis, a recursive algorithm for precise frequency and rate of change of frequency measurement is presented. The algorithm consists of three major steps. First, a rough frequency estimation for a data window is computed using a second order least error square approximation on the phasor angles of the input waveform. Then, a resampling based on the rough frequency estimation is carried out, followed by another second order least error square approximation to obtain the final results. The results of simulations using this approach are provided. / Master of Science

Thesis (MMus (Music))--University of Stellenbosch, 2009 / Violin vibrato is the action by which a violinist periodically changes the frequency of a sustained note by moving the finger on the string, rapidly backwards and forwards. If it is artistically applied, it adds life, character and warmth to an otherwise dull sounding note. Although it has been used since the sixteenth century, very little research has been done on the reason why humankind would experience such periodic fluctuations as an object of beauty in violin performance. In answering the question, this study explores a variety of angles of approach in order to understand the phenomenon in its full context. The history, development and geographical origin of the technique are firstly discussed in a diachronic fashion and provide the background for the subsequent synchronic research on the physical nature of violin sound and violin vibrato. The vibrato rates and widths of four virtuosi are measured and compared to highlight the differences and individuality which are argued to be a contributing factor to the perception of beauty of the technique. It is established in the final chapter that the brain is stimulated more by sounds with periodic changes than those that are presented in the steady-state which cast some light on why vibrato may be experienced as an appreciated addition to sound. The thesis aims to present a unique view on the possibilities of interdisciplinary research of the phenomenon of violin vibrato. It further aims to present the research findings in a concise, logical, and systematic manner that could be of interest to both musician and scientist.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Robert Bradlee Campbell. / Ph.D.

In the first part of the dissertation, a novel stochastic averaging technique based on a Hilbert transform definition of the oscillator response displacement amplitude is developed. In comparison to standard stochastic averaging, the requirement of “a priori” determination of an equivalent natural frequency is bypassed, yielding flexibility in the ensuing analysis and potentially higher accuracy. Further, the herein proposed Hilbert transform based stochastic averaging is adapted for determining the time-dependent survival probability and first-passage time probability density function of stochastically excited nonlinear oscillators, even endowed with fractional derivative terms. To this aim, a Galerkin scheme is utilized to solve approximately the backward Kolmogorov partial differential equation governing the survival probability of the oscillator response. Next, the potential of the stochastic averaging technique to be used in conjunction with performance-based engineering design applications is demonstrated by proposing a stochastic version of the widely used incremental dynamic analysis (IDA). Specifically, modeling the excitation as a non-stationary stochastic process possessing an evolutionary power spectrum (EPS), an approximate closed-form expression is derived for the parameterized oscillator response amplitude probability density function (PDF). In this regard, IDA surfaces are determined providing the conditional PDF of the engineering demand parameter (EDP) for a given intensity measure (IM) value. In contrast to the computationally expensive Monte Carlo simulation, the methodology developed herein determines the IDA surfaces at minimal computational cost. In the second part of the dissertation, a novel multiple-input/single-output (MISO) system identification technique is developed for parameter identification of nonlinear and time-variant oscillators with fractional derivative terms subject to incomplete non-stationary data. The technique utilizes a representation of the nonlinear restoring forces as a set of parallel linear sub-systems. Next, a recently developed L1-norm minimization procedure based on compressive sensing theory is applied for determining the wavelet coefficients of the available incomplete non-stationary input-output (excitation-response) data. Several numerical examples are considered for assessing the reliability of the technique, even in the presence of incomplete and corrupted data. These include a 2-DOF time-variant Duffing oscillator endowed with fractional derivative terms, as well as a 2-DOF system subject to flow-induced forces where the non-stationary sea state possesses a recently proposed evolutionary version of the JONSWAP spectrum. In the third part of this dissertation, a joint time-frequency analysis technique based on generalized harmonic wavelets (GHWs) is developed for dynamic cerebral autoregulation (DCA) performance quantification. DCA is the continuous counter-regulation of the cerebral blood flow by the active response of cerebral blood vessels to the spontaneous or induced blood pressure fluctuations. Specifically, various metrics of the phase shift and magnitude of appropriately defined GHW-based transfer functions are determined based on data points over the joint time-frequency domain. The potential of these metrics to be used as a diagnostics tool for indicating healthy versus impaired DCA function is assessed by considering both healthy individuals and patients with unilateral carotid artery stenosis. Next, another application in biomedical engineering is pursued related to the Pulse Wave Imaging (PWI) technique. This relies on ultrasonic signals for capturing the propagation of pressure pulses along the carotid artery, and eventually for prognosis of focal vascular diseases (e.g., atherosclerosis and abdominal aortic aneurysm). However, to obtain a high spatio-temporal resolution the data are acquired at a high rate, in the order of kilohertz, yielding large datasets. To address this challenge, an efficient data compression technique is developed based on the multiresolution wavelet decomposition scheme, which exploits the high correlation of adjacent RF-frames generated by the PWI technique. Further, a sparse matrix decomposition is proposed as an efficient way to identify the boundaries of the arterial wall in the PWI technique.