Thesis (Ph. D.)--California Institute of Technology, 1983. / Includes bibliographical references.

The problem of fitting a material property of the earth to a certain model by analysing a returned seismic signal is investigated here. Analysis proceeds with methods taken from the theory of inverse problems. Seismic wave inversion is tack- led by minimisation of the objective function with respect to the model parameters. Absorbing boundary conditions are implemented using an exponentially decaying ansatz. / Physics / Ph. D. (Physics)

This thesis describes the beach field-testing of a 2-degree-of-freedom (2-DOF) transverse line Rayleigh wave source for use in a seismo-acoustic SONAR for buried mine detection. The source is composed of six identical modules, each composed of two radial and two vertical inertial mass shakers, all mounted to a common base plate. The vertical and horizontal excitation of each module is independent. Electrically, the six modules are organized into three independent sets of two. The length of the source is 46 inches (1.17m), the width 6 inches (0.15m) and the weight 126 pounds (562N). Field tests were conducted using a 5-cycle, (smooth-)amplitude-modulated transient excitation signal. Based on past and present experience that the Rayleigh wave speed at the beach test site is approximately 90 m/s, a carrier frequency of 100 Hz was employed, producing a Rayleigh wavelength and surface penetration depth of approximately 1 m (approximately equal to the source aperture length), which is appropriate for the intended application. The source radiation directional characteristics were investigated for various relative amplitudes and phases of vertical and horizontal shaker excitation. A null result was obtained, that is, no unambiguous evidence of directivity was observed in any of the experiments conducted using this source. These included measurements wherein the source modules were removed from the common base plate and emplaced on the sand. The reason for this result is unknown, but it is suspected that a good possibility is that the beach sand medium just below its surface, whereupon the present source and receivers were deployed, is not homogeneous enough to support coherent spatial beamforming. Based upon the past success of a 4-element end-fire line array in producing directional Rayleigh wave radiation (10-15 dB front-to-back rejection), it is suggested that, if such a source can be made mobile, it may well be the best source candidate for a seismo-acoustic SONAR for buried mine detection.

"July 2004" / Bibliography: leaves 215-230. / viii, 230 leaves : ill., maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Chemistry and Physics, Discipline of Physics, 2004

Graduation date: 1995 / Best scan available for figures.

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 293-298). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references (p. 259-263). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M.S. in C.E.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2004. Directed by Glenn J. Rix. / Includes bibliographical references (leaves 94-97).