Thesis (M.S.)--Montana State University--Bozeman, 2006. / Typescript. Chairperson, Graduate Committee: Ross K. Snider. Includes bibliographical references (leaves 101-102).

Thesis (Doctor of Technical Sciences)--Swiss Federal Institute of Technology, Zurich, 2003. / "Diss. ETH No. 14760" "April 2003" Includes bibliographical references and index.

Thesis (Ph. D.)--Washington State University, May 2006. / Includes bibliographical references (p. 91-94).

Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaves 79-82).

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 144-150). Also available in electronic version.

Thesis (M.S. in computer science)--Washington State University, May 2007. / Includes bibliographical references (p. 36).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references and index.

The work presented in this thesis consists of two parts: development and application of a novel passive acoustical approach for field measurement of breaking surface waves, and interpretation of the resulting observations in terms of wave field information so as to improve the understanding of wave breaking. The development of the acoustical approach has been motivated by the difficulties inherent in measurement of breaking waves. This approach makes use of an array of four broadband hydrophones which is able to track individual breaking waves by passive detection of the naturally generated sound of wave breaking. The Generalized Cross Correlation method is used to determine time differences of acoustic signals from breaking waves arriving at the array, allowing the breaking waves to be located with the given array geometry. Observations of breaking waves were made by means of this technique during the Surface Wave Processes Program (SWAPP). The spatial and temporal statistics of breaking waves, including breaking wave density, travel velocity, lifetime of breaking and spacing, are obtained from the observations. Statistical models are developed to assess, and where appropriate, correct for any bias resulting from limitations of the measurement approach. The breaking wave statistics provide important information about the physical process of wave breaking and its distribution in different wave fields. It is found that wave breaking in the open ocean occurs at a scale substantially smaller than the scale associated with the dominant wind wave component in the wave spectrum. Numerical simulation of breaking wave statistics and comparison with the observations demonstrates that the scale of breaking can be predicted from the directional wave spectrum by a linear model with a single breaking threshold. These results will provide input to comprehensive models of wave dissipation. Acoustical radiation properties of individual breaking waves are a further aspect of wave breaking that has been observed with the aforementioned technique. Investigation of the sound radiated from breaking waves reveals information both on the nature of the sound generation mechanism by breaking and the dimension of breaking waves. Statistical analysis of the acoustic source intensity associated with wave breaking suggests that the source intensity can be related to the breaking scale and wave energy dissipation, thus implying that surface wave dissipation could be remotely measured by using ambient sound. / Graduate

Side effects of frequency reuse are discussed, particularly co-channel interference in scalar measurement FM systems. Continuous and discrete time state-space models for multiple source angle modulated communications environments are developed and coupled digital phase-locked loop (CDPLL) estimator structures are derived based on the Extended Kalman Filter (EKF). Separability of two sources is investigated by examination of state observability and by simulations of the derived estimators. The relationship between the EKF and the CDPLL is presented and their linear and nonlinear behavior discussed. Acquisition and tracking characteristics are simulated and results presented. The new estimator is compared to related efforts found in the literature. The effects of time-varying signal multiplicity is briefly treated. An example of polarization diversity for frequency reuse (vector measurement) is also presented and is shown to be adequately modeled by the derived communications model. / Graduate

Airborne laser bathymetry, a relatively new state-of-the-art technology for the mapping of sea depth by using active airborne laser ranging systems, has proved successful for charting shallow waters worldwide including Canada, Australia, and the United States. In order to improve the reliability and efficiency of using airborne laser ranging systems, in particular, the Canadian LARSEN 500 airborne system, for the estimation of sea depth, one- and two-dimensional (1-D and 2-D) signal processing algorithms are developed. The processing involved is carried out in a two-phased approach. In phase I, 1-D signal processing is explored. Specifically, 1-D digital smoothing is applied to the laser waveforms for noise reduction. Results show that this process can remove noise while preserving the important characteristics of the laser signal. In order to analyze the laser reflections quantitatively, a mathematical model function that can be used to characterize the smoothed laser waveforms received by the LARSEN 500 under diverse circumstances is established. Two algorithms are also developed for the detection of the peak of the laser pulse reflected from the sea surface and bottom. The algorithms have been implemented and tested extensively with real-world LARSEN waveforms. Tests show that the algorithms can reject noise pulses and pulses arising from turbid layers in the sea and locate the correct pulse in the presence of varying degrees of noise. In order to separate the surface and bottom reflections independently of the degree of their overlap, a waveform-decomposition technique based on a robust optimization method is developed. An initialization scheme is also developed in conjunction with the decomposition technique which can reduce the amount of computation required in the decomposition quite significantly. Comparison resuits obtained from statistical analysis show that the proposed technique offers considerable potential in improving the depth estimates particularly when the resolution between the surface and bottom reflections is low. In addition, it can be used to automate the depth estimation process. In phase II, 2-D signal processing is used to improve the reconstruction of ocean topography from individual depth estimates. A type of 2-D interpolating filter is introduced to suppress impulsive noise present in the scattered measurements. It is found that as a result of the filtering, the representation of the sea floor, which can be in the form of 2-D contour maps or 3-D surface plots, becomes a more accurate representation of the ocean bottom. To improve the accuracy in the reconstruction, a sophisticated triangle based 2-D interpolation technique designed using the finite-element method is applied. To increase the reliability of the reconstruction, optimal triangulated irregular networks are constructed before carrying out the interpolation. In order to assess the accuracy of the decomposition results when the resolution between the laser reflections is very low, a procedure which incorporates the 2-D interpolation technique is developed. To further enhance the reconstructed profiles, an adaptive 2-D filtering procedure is introduced. This procedure is developed using 2-D power spectral analysis of the depth profiles. In areas where the signal characteristics of the bathymetric data vary rapidly, 2-D filtering based on minimum mean-squared error estimation is explored. It is shown that the derived filter is a 2-D space-variant filter and its application to bathymetric profiles collected by the LARSEN 500 system is also implemented. Results obtained show that these two filtering procedures are useful in reducing random noise inherent in the reconstructed profiles which is difficult to detect and eliminate in 1-D processing. / Graduate