Thesis (M.S.)--Western Washington University, 2005. / Includes bibliographical references (leaves 114-123). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.S.)--Western Washington University, 2005. / Includes bibliographical references (leaves 114-123).

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 191-196).

Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xx, 393 p. : ill. (some col.), maps (some col.). Vita. Includes abstract. Includes bibliographical references (p. 356-371).

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on November 19, 2009). Thesis advisor: Dr. John R. Jones. Includes bibliographical references.

Vision provides the primary means by which many animals distinguish foreground objects from their background and coordinate locomotion through complex environments. The present thesis focuses on mechanisms within the visual system that afford figure-ground segregation and self-motion perception. These processes are modeled as emergent outcomes of dynamical interactions among neural populations in several brain areas. This dissertation specifies and simulates how border-ownership signals emerge in cortex, and how the medial superior temporal area (MSTd) represents path of travel and heading, in the presence of independently moving objects (IMOs). Neurons in visual cortex that signal border-ownership, the perception that a border belongs to a figure and not its background, have been identified but the underlying mechanisms have been unclear. A model is presented that demonstrates that inter-areal interactions across model visual areas V1-V2-V4 afford border-ownership signals similar to those reported in electrophysiology for visual displays containing figures defined by luminance contrast. Competition between model neurons with different receptive field sizes is crucial for reconciling the occlusion of one object by another. The model is extended to determine border-ownership when object borders are kinetically-defined, and to detect the location and size of shapes, despite the curvature of their boundary contours. Navigation in the real world requires humans to travel along curved paths. Many perceptual models have been proposed that focus on heading, which specifies the direction of travel along straight paths, but not on path curvature. In primates, MSTd has been implicated in heading perception. A model of V1, medial temporal area (MT), and MSTd is developed herein that demonstrates how MSTd neurons can simultaneously encode path curvature and heading. Human judgments of heading are accurate in rigid environments, but are biased in the presence of IMOs. The model presented here explains the bias through recurrent connectivity in MSTd and avoids the use of differential motion detectors which, although used in existing models to discount the motion of an IMO relative to its background, is not biologically plausible. Reported modulation of the MSTd population due to attention is explained through competitive dynamics between subpopulations responding to bottom-up and top- down signals.

In high impact human activities, much of the impact shock wave is dissipated through internal body structures, preventing excessive accelerations from reaching vital organs. Mechanisms responsible for this attenuation, including lower limb joint compression and spinal compression have been neglected in existing whole-body simulation models. Accelerometer data on one male subject during drop landings and drop jumps from four heights revealed that peak resultant acceleration tended to decrease with increasing height in the body. Power spectra contained two major components, corresponding to the active voluntary movement (2 Hz 14 Hz) and the impact shock wave (16 Hz 26 Hz). Transfer functions demonstrated progressive attenuation from the MTP joint towards the C6 vertebra within the 16 Hz 26 Hz component. This observed attenuation within the spine and lower-limb joint structures was considered within a rigid body, nine-segment planar torque-driven computer simulation model of drop jumping. Joints at the ankle, knee, hip, shoulder, and mid-trunk were modelled as non-linear spring-dampers. Wobbling masses were included at the shank, thigh, and trunk, with subject-specific biarticular torque generators for ankle plantar flexion, and knee and hip flexion and extension. The overall root mean square difference in kinetic and kinematic time-histories between the model and experimental drop jump performance was 3.7%, including ground reaction force root mean square differences of 5.1%. All viscoelastic displacements were within realistic bounds determined experimentally or from the literature. For an equivalent rigid model representative of traditional frictionless pin joint simulation models but with realistic wobbling mass and foot-ground compliance, the overall kinetic and kinematic difference was 11.0%, including ground reaction force root mean square differences of 12.1%. Thus, the incorporation of viscoelastic elements at key joints enables accurate replication of experimentally recorded ground reaction forces within realistic whole-body kinematics and removes the previous need for excessively compliant wobbling masses and/or foot-ground interfaces. This is also necessary in cases where shock wave transmission within the simulation model must be non-instantaneous.

The aim of this study is to propose an alternative approach in prognostics for airborne avionics system in order to enhance maintenance process and aircraft availability. The objectives are to analyse the dependency of avionic systems for fault propagation behaviour degradation, research and develop methods to predict the remaining useful life of avionics Line Replaceable Units (LRU), research and develop methods to evaluate and predict the degradation performances of avionic systems, and lastly to develop software simulation systems to evaluate methods developed. One of the many stakeholders in the aircraft lifecycle includes the Maintenance, Repair and Overhaul (MRO) industry. The predictable logistics process to some degree as an outcome of IVHM gives benefit to the MRO industry. In this thesis, a new integrated numerical methodology called ‘System Level Airborne Avionic Prognostics’ or SLAAP is developed; looking at a top level solution in prognostics. Overall, this research consists of two main elements. One is to thoroughly understand and analyse data that could be utilised. Secondly, is to apply the developed methodology using the enhanced prognostic methodology. Readily available fault tree data is used to analyse the dependencies of each component within the LRUs, and performance were simulated using the linear Markov Model to estimate the time to failure. A hybrid approach prognostics model is then integrated with the prognostics measures that include environmental factors that contribute to the failure of a system, such as temperature. This research attempts to use data that is closest to the data available in the maintenance repair and overhaul industry. Based on a case study on Enhanced Ground Proximity Warning System (EGPWS), the prognostics methodology developed showed a sufficiently close approximation to the Mean Time Before Failure (MTBF) data supplied by the Original Equipment Manufacturer (OEM). This validation gives confidence that the proposed methodology will achieve its objectives and it should be further developed for use in the systems design process.

The presented work deals with the evaluation of the Mesolithic and Neolithic settlement in a specific area of the northern part of the Českobudějovicko region, which covres the northwest part of the Třeboň basin from a geographical point of view. The work brings information from already known as well as newly registered sites in a given spatial settings and also in the context of natural environment. For these purposes, the method of surface collections, resources review and evaluation of the results using GIS have been applied.

Elevated water tanks are widely used to store water for drinking as well as for fire extinguishing purposes. After a severe earthquake, the need of water for drinking as well as fire control will increase dramatically. To ensure that water tanks remain functional after an earthquake, proper analysis method should be followed in order to calculate the response of a structure for earthquake. In this study, the lateral forces developed during earthquake are investigated from commercially available SAP2000 software and the results are compared with the 2006 edition of the ACI standard "Seismic Design of Liquid-Containing Concrete Structures and Commentary" (ACI 350.3-06). The elevated concrete tank is modeled for full, half-full and empty conditions. Linear modal time history analysis is performed using scaled ground motions. Three-directional ground motion records from five different earthquakes have been scaled to the design level and applied to the structure. Sloshing behavior of water inside the tank and the effect of vertical ground motion on the columns have been investigated. It is found that, vertical ground motions can increase the axial forces in columns by up to 20 %, and the ACI 350.3-06 design method is not always conservative. As seismic response depends on both the dynamic properties of the structure and the spectral characteristics of ground motions, more research is needed to understand and model the seismic response of elevated water tanks.