Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (January 19, 2010) Includes bibliographical references (p. 62-65)

Thesis (M.Sc.)--Memorial University of Newfoundland, 2006. / Bibliography: leaves 141-147. Also available online.

The potential benefits of autonomous satellite formation flying in such areas as high- resolution remote sensing, and sparse aperture radar, has stimulated interest in modeling the satellite environment for feasibility and simulation studies to help explore and define the technical challenges that must be solved in order to achieve successful autonomous satellite formations. The purpose of this paper is to develop and describe a numerical simulation of the orbital environment including central force field perturbations and atmospheric drag effects which will be a useful analytical tool for investigating issues relating to maintaining satellite formations in low-earth-orbit. Many of the studies done in this area confine their research to circular orbits, with and without perturbation effects. This study will investigate apply orbital dynamic equations to the problem of maintaining satellite formations in both circular and elliptical orbits, with and without the presence of J2 gravity perturbation effects and atmospheric drag. This effort is primarily focused on modeling the orbital mechanics of one and two satellites in the presence of J2 and drag perturbations This effort is being performed as part of a multi-disciplined University of Central Florida KnightSat project, sponsored by the Air Force, to develop a two-satellite formation in the nanosatellite class, for investigating issues related to using formation satellites for remote earth sensing, to develop three-dimensional mapping.

<p> A finite element method, incorporating the Hellinger-Reissner variational principle, has been developed for calculations of stress-strain and pore pressure for undrained and drained soil deformations. The soil is considered as cross-isotropically elastic material to account for the anisotropy of soil behaviour resulting from geological formations. A general expression for pore pressure parameters, taking into account the consolidation condition, has been hypothesized. Experimental investigations of consolidated undrained triaxial tests have been performed to study the validity of this expression.</p> / Thesis / Doctor of Philosophy (PhD)

No description available.

In typical attempts to control spatio-temporal chaos, spatially extended systems were subjected to protocols that perturbed them as a whole, often overlooking the potential stabilizing interaction between adjacent regions. We have shown that through the application of a time-delayed feedback scheme to a specific localized region of a system periodic patterns can be generated that are distinct from those observed when controlling the whole system. In this thesis, we present the results of two interconnected studies: 1) Spatio-temporal patterns emerging from spatially localized time-delayed feedback perturbations within transient chaotic states of the Gray-Scott reaction-diffusion system 2) Spatio-temporal patterns emerging from spatially localized time-delayed feedback perturbations within chaotic states of the cubic complex Ginzburg-Landau equation We present an investigation of two model systems: the Gray-Scott reaction-diffusion equation and the complex Ginzburg-Landau equation. Specifically we numerically study two models characterized by exhibiting various chaotic regimes. We first consider a comprehensive study of the Gray-Scott model highlighting key details about different parameter space regimes and their relative proximity to the chaotic regime. Through a systematic investigation of the effects of the model control parameters, time-delayed feedback control strength parameters, perturbed region widths, and other quantities, we show that novel patterns can be formed through the appropriate choice of perturbation region and strength. For the second study we use spatially localized time-delayed feedback on the one-dimensional complex Ginzburg-Landau equation and demonstrate, through the numerical integration of the resulting real and imaginary equations, the stabilization of novel periodic patterns within three distinct chaotic regimes. In these studies we have shown that selectively applying a time-delayed feedback scheme to a specific spatially localized region of a chaotic system can bring forth periodic patterns that are distinct from those observed when applying a perturbation to the whole system. Depending on the protocol used, these new patterns can emerge either in the perturbed or the unperturbed region. The mechanism underlying the observed pattern generation is related to the interplay between diffusion across the interfaces separating the different regions and time-delayed feedback. Research was sponsored by the Army Research Office and was accomplished under Grant No. W911NF-17-1-0156. / Doctor of Philosophy / In typical attempts to control spatio-temporal chaos, spatially extended systems were subjected to protocols that perturbed them as a whole, often overlooking the potential stabilizing interaction between adjacent regions. We have shown that through the application of a time-delayed feedback scheme to a specific localized region of a system periodic patterns can be generated that are distinct from those observed when controlling the whole system. We present an investigation of two model systems: the Gray-Scott reaction-diffusion equation and the complex Ginzburg-Landau equation. We first consider a comprehensive study of the Gray-Scott model highlighting key details about different parameter space regimes and their relative proximity to the chaotic regime. Through a systematic investigation of the effects of the model control parameters, time-delayed feedback control strength parameters, perturbed region widths, and other quantities, we show that novel patterns can be formed through the appropriate choice of perturbation region and strength. For the second study we use spatially localized time-delayed feedback on the one-dimensional complex Ginzburg-Landau equation and demonstrate, through the numerical integration of the resulting real and imaginary equations, the stabilization of novel periodic patterns within chaotic regimes. In these studies we have shown that selectively applying a time-delayed feedback scheme to a specific region of a chaotic system can generate periodic patterns that are distinct from those observed when controlling the whole system. Depending on the protocol used, these new patterns can emerge either in the perturbed or the unperturbed region. The mechanism underlying the observed pattern generation is related to the interplay between diffusion across the interfaces separating the different regions and time-delayed feedback. Research was sponsored by the Army Research Office and was accomplished under Grant No. W911NF-17-1-0156.

The source of the New York - Alabama Magnetic Lineament (NY AML) is revealed on newly reprocessed seismic reflection data, and the Grenville Front Tectonic Zone (GFTZ) is imaged beneath it in eastern Tennessee. Industry data, correlated to lower crustal depths, image a wedge-shaped block beneath the shelf strata of the Cumberland Plateau and Valley and Ridge provinces of eastern Tennessee. Two dimensional gravity and magnetic modeling corroborate the interpretation that the contrast in density and magnetic susceptibility between the wedge and the adjacent crust produces the Lineament. The boundary across which the contrast is generated dips approximately 30° northwest. East-dipping reflections imaged below 7 seconds can be extended northwest to the surface where they align with the position of the Grenville Front. The reflections are interpreted as evidence of deformation related to the GFTZ in Canada. The mid-crustal band of reflectivity visible on most of the reflection profiles lies above the east-dipping reflections and is interpreted to delineate the eastern margin of the GFTZ. The crust southeast of the wedge-shaped block exhibits high reflectivity with well-developed west-dipping events. The west-dipping events might correlate to those reported in Ohio on COCORP data, suggesting that they are pervasive in the basement throughout the eastern United States. The fabric is interpreted to have formed during the continent-continent collision of the Grenville Orogeny. The absence of west-dipping reflections within the wedge suggests that the wedge is younger than the development of the fabrics recorded by the reflections. Vertical dike swarms are interpreted to intrude the west-dipping fabric. The swarms model as felsic and appear on migrated data to be older than uplift, erosion, and deposition of the shelf strata. Crustal thickness estimates by previous authors of over 45 km are corroborated with interpreted images of the Moho on two deeper reflection profiles. The thick crust might be the locus of anatectic melting following Grenville collision. The emplacement of granitic or granodioritic magmas provides an explanation for the density, magnetic susceptibility, and difference in reflectivity of the wedge-shaped block. The New York - Alabama Magnetic Lineament diverges from the location of the Grenville Front north of the study area. The position of the NYAML can be interpreted to represent the axis of anatectic melting following collision, and indicates that the thickest part of the crust formed farther east of the Front in Canada than in Tennessee. Pseudomagnetic field investigations permit the distinction between the source of the New York - Alabama Magnetic Lineament and adjacent high susceptibility sources to the northwest. The sources to the northwest appear from the modeling to be mafic intrusions that might be related to the Norris Lake peridotite. Earthquake locations in the Eastern Tennessee Seismic Zone (ETSZ) are aligned along the southwest edge of the gradient of the NY AML, and fall within the crust characterized by strong west-dipping reflections. Because the contact between the wedge and the region of west-dipping reflections is dipping to the northwest, the relationship between the NYAML and the ETSZ is not clear. More accurate hypocenter locations are necessary to clarify whether the earthquakes are restricted to the region of the crust typified by west dip. If not, the relationship between the earthquakes and the NYAML might be coincidental. A velocity model that considers the dipping boundaries in these reflection data should result in hypocenter locations that can constrain the relationship. / Ph. D.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: John C. Kraft, Dept. of Geology. Includes bibliographical references.

The Eocene Cocoa Sand Member of Yazoo Formation is fine grained, moderately to well sorted, poorly cemented, quartz arenite. Surface exposures are poor, but it has been mapped from west Choctaw County, Alabama to eastern Jasper County, Mississippi. In the subsurface, the Cocoa Sand Member is identified by obvious protrusion both in Spontaneous and Resistivity Logs. Northeast to southwest cross-sections (perpendicular to the paleo-shoreline) and northwest to southeast cross-sections (parallel to the paleo-shoreline) were developed, along with isopach maps, to determine the sequence stratigraphic setting and a depositional model of the Cocoa Sand Member. Previous work has interpreted the Cocoa Sand Member as a shelf margin sand deposited as part of a lowstand systems tract or as a transgressive sand. Grain size analysis indicates that the sand coarsens upward and there is evidence in core that the upper contact of the Cocoa sand with the Pachuta Marl is sharp, representing an upper erosion surface. The presence of rip-up clasts at the base of the Cocoa sand member supports the presence of a transgressive surface at the contact with the North Twistwood Creek. Based on the sand thickness distribution as identified in the Cocoa Sand isopach map and cross sections, two sand ridges have been recognized extending nearly parallel to the paleoshoreline across the Mississippi and Alabama. A three stage model is presented suggesting the formation of these ridges during transgression with the source of the sand being from the eroded and reworked underlying North Twistwood Creek Member. / Department of Geological Sciences

No description available.