Thesis (M.S.) in Mechanical Engineering--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 59-62).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1967. / Includes bibliographical references (p. 114-116).

Thesis (Ph. D.)--University of Hong Kong, 1989.

Thesis--M. Sc.(Eng.), University of Hong Kong. / Errata slip inserted. Mimeographed.

Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains x, 172 p. : ill. Includes abstract. Includes bibliographical reference.

This dissertation is a continuation of the work by Zabolotskaya (Sov. Phys. Acoust. 32, 296-299 (1986)) and Wochner et al. (J. Acoust. Soc. Am. 125, 2488-2495 (2008)) on the nonlinear propagation of shear wave beams in an isotropic solid. In those works, a coupled pair of nonlinear parabolic equations was derived for the transverse components of the particle motion in a collimated shear wave beam, accounting consistently for the effects of diffraction, viscosity and nonlinearity. The nonlinearity includes a cubic nonlinear term that is equivalent to the nonlinearity present in plane shear waves, as well as a quadratic nonlinear term that is unique to diffracting beams. The purpose of this work is to investigate the quadratic nonlinear term by considering second-harmonic generation in Gaussian beams as a second-order nonlinear effect using standard perturbation theory. Since shear wave beams with translational polarizations (linear, elliptical, and circular) do not exhibit any second-order nonlinear effects, we broaden the class of source polarizations considered by including higher-order polarizations that account for stretching, shearing and rotation of the transverse plane. We find that the polarization of the second harmonic generated by the quadratic nonlinearity is not necessarily the same as the polarization of the source-frequency beam, and we are able to derive a general analytic solution for second-harmonic generation that gives explicitly the relationship between the polarization of the source-frequency beam and the polarization of the second harmonic. Additionally, we consider the focusing of shear wave beams with this broader class of source polarizations, and find that a tightly-focused, radially-polarized shear wave beam contains a highly-localized region of longitudinal motion at the focal spot. When the focal distance of the beam becomes sufficiently short, the amplitude of the longitudinal motion becomes equal to the amplitude of the transverse motion. This phenomenon has a direct analogy in the focusing properties of radially-polarized optical beams, which was investigated experimentally by Dorn et al. (Phys. Rev. Lett. 91, 233901 (2003)). / text

published_or_final_version / abstract / toc / Civil Engineering / Master / Master of Philosophy

No description available.

On the Canadian Prairies, canola is a main source for biodiesel production and wheat is the primary feedstock for bioethanol production. To raise biofuel production requires a movement of resources and land away from food and grain crops, which would cause food to become scarcer and increase its price. This paper determines the impact of more biofuels production on the food industry. It considers the simultaneous estimation of share equations from both revenue function and distance function. Econometric results exploit the non-stationary nature of the data and the correlations among shares between primal and dual models are exploited by cointegration techniques. Johansen’s maximum likelihood estimator is applied to 1971-2007 data from Manitoba, Alberta and Saskatchewan. Morishima elasticity estimates indicate high long run substitutions among crops (wheat, feed grains and canola). A rise in the production of biofuel crops could cause food prices to increase, both for meat and bread.

No description available.