Numerical models using one- and two-layer generalized geostrophic equations are developed and applied to the study of geostrophic turbulence. The classical results of geostrophic turbulence are extended by freeing the experiments from the restriction of weak vertical displacements, thereby allowing finite-amplitude, frontal effects. / Turbulence experiments with the one-layer model reveal an attracting length scale, which depends on the energy level. When the frontal effects are present, anticyclones merge into a few, coherent, large, and long-lived eddies, while cyclones shatter and form a small-scale, quasi-geostrophic background. / Experiments with the two-layer model indicate that a distinction exists between geostrophic turbulence at high and low energy levels. At high energy levels, when frontal effects are present and when the traditional quasi-geostrophic model is invalid, large, coherent anticyclones emerge from motions at scales less than the deformation radius; these are robust and retain their potential energy against the destructive action of baroclinic instability. This is an important new result, because so far, with only quasi-geostrophic models in use, it has long been thought that such eddies were unstable. Experiments with isolated eddies of varying sizes and amplitudes, with variable strength of the $\beta$ effect and with variable depth of the lower layer reveal that, at the finite amplitudes, anticyclones are far more stable than cyclones, and that strong anticyclones are more stable than weak eddies of either polarity. Eddies are also stable as the lower layer is deepened. The $\beta$-effect is destablizing when the lower layer is infinitely deep, and is stabilizing when the lower layer has a finite depth. / Source: Dissertation Abstracts International, Volume: 51-01, Section: B, page: 0370. / Major Professor: Benoit Cushman-Roisin. / Thesis (Ph.D.)--The Florida State University, 1989.

<p> Very Low Frequency (VLF 3-30 kHz) receivers are used to monitor the amplitude and phase of signals from powerful naval VLF communication transmitters. Since the VLF transmitter signals propagate in the Earth-ionosphere waveguide, they provide a method for remotely sensing ionospheric density changes. The effect of powerful natural oceanic lighting discharges on the ionosphere are investigated using VLF remote sensing and the Global Lighting Detection Network (GLD360). Ionospheric disturbances known as Lighting-induced Electron Precipitation (LEP) events and Early/Fast events are investigated. A comprehensive numerical model of the electron precipitation process is used to compare to observation. Results are compared to previous research on lightning effects on the ionosphere. </p>

<p> This thesis proposes a model-based control of a high performance marine vessel. With this model-based control, comprehensive controls based on the dynamics of the marine vessel will be obtained. The dynamics of the Anaconda, a high performance marine vessel built by Swiftships, Inc., were studied, and equations of motion reflecting the dynamics of the ship were created. </p><p> Using the equations of motion, the Anaconda was modeled and multiple point-to-point maneuvers were conducted to predict the movement of the boat in a constant current environment. Transfer functions were developed from the equations of motion and compared to transfer functions obtained from a system identification test done experimentally on the Anaconda to show the validity of the model. The system identification test consisted of a turning and acceleration response.</p><p> Using the controls gained from the model-based control, simulated heading changes were compared to experimental heading changes. These same controls were used to perform autonomous waypoint testing with the Anaconda. Since the model-based control was used the Anaconda was able to follow an ideal path relatively closely. A straight line, polygon, circle, and figure 8 autonomous waypoint tracking was performed. The RMS errors were relatively low compared to the errors present in the sensors that were used in measuring the Anaconda's performance.</p>

Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Available in ProQuest Dissertation database. Subscribing Libraries only.

Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Subscription resource available via Digital Dissertations only.

Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Subscription resource available via Digital Dissertations only.

Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Subscription resource available via Digital Dissertations only.

Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given. / Subscription resource available via Digital Dissertations only.

Thesis (Ph.D.)--University of South Florida, 2006. / (UMI)AAI3240418. Adviser: Kent Fanning. Source: Dissertation Abstracts International, Volume: 67-10, Section: B, page: 5994.

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