Ulm, Univ. Diss., 2006.

Techn. Univ., Diss., 2009--München.

Thesis (M. Communication Pathology)--University of Pretoria, 2004. / Includes bibliographical references.

Thesis (Ph.D.)--Pennsylvania State University, 2005. / Mode of access: World Wide Web.

München, Techn. Univ., Diss., 2004.

München, Techn. Univ., Diss., 2001.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references (leaves 157-169).

The goal of this thesis was to develop a framework for modeling relevant environmental performance metrics and objectively simulating the future environmental impacts of aviation given the evolution of the fleet, the development of new technologies, and the expansion of airports. By exchanging fidelity for computational speed, a screening-level framework for assessing aviation's environmental impacts can be developed to observe new insights on fleet-level trends and inform environmental mitigation strategies. This was accomplished by developing per class average ``generic-vehicle" models that can reduce the fleet to a few representative aircraft models for predicting fleet results with reasonable accuracy. The method for Generating Emissions and Noise, Evaluating Residuals and using Inverse method for Choosing the best Alternatives (GENERICA) expands a previous generic vehicle formulation to additionally match DNL contours across a subset of airports. Designs of experiments, surrogate models, Monte Carlo simulations, and ``desirability" scores were combined to set the vehicle design parameters and reduce the mean relative error across the subset of airports. Results show these vehicle models more accurately represented contours at busy airports operating a wide variety of aircraft as compared to a traditional representative-in-class approach. Additionally, a rapid method for assessing population exposure counts was developed and incorporated into the noise tool, and the generic vehicles demonstrated accuracy with respect to population exposure counts for the actual fleet in the baseline year. The capabilities of the enabled framework were demonstrated to show fleet-level trends and explore placement of new runways at capacity constrained airports.

This work is divided into two main parts, investigational and theoretical. The first part deals with the investigation of deposition values around integrated iron and steel works, and coke works, in South Wales, and with the changes in such values which arise as a result of modifications to process control or to arrestment equipment. A method of evaluation of such changes, based on the cumulative sum technique, is developed, which m1n1m1ses the effect of seasonal variations in the deposition values. It is demonstrated that there are two significant sources of particulate emission, from coke oven discharges, and from coke quenching. These are shown to have different spatial distributions, emissions from quench towers being very widespread, whereas emissions from oven discharges deposit relatively closer to the source. Methods to reduce both of these sources are described: It is shown that the use of arrestors in quench towers leads to enhanced emission of dissolved solids, but that the increase can be controlled by the use of additional sprays above the arrestors. The second part considers some theoretical aspects of quench tower operation. It is shown that the installation of arrestors leads to changes in gas temperature and gas composition in a quench tower, which cause increases in terminal settling velocity. The same changes lead to reduced condensation within the quench tower, and hence greater emission of steam, which gives a more buoyant emission, with more widespread dispersion than from open quench towers, as well as enhanced emissions of dissolved solids. Calculations are included which confirm the extent of the dispersion from towers fitted with arrestment devices.

M.Ing. (Electrical and Electronic Engineering) / This dissertation presents a comprehensive electrical model of the human auditory periphery. The model focuses on the generation and transmission of otoacoustic emissions (OAEs) under biometric conditions. The auditory system model was divided and studied in three sections, namely the outer, middle and inner ear sections. Existing models were used and improved for the study. The outer ear model was derived using electroacoustic analogies. The middle ear model was derived empirically. The inner ear model was derived by relating the mechanical properties of the inner ear to electrical principles. The outer ear model includes an analog diffraction circuit and a linear transmission line representation of the auditory canal and the concha. The variation of the radius of the auditory canal along its length was incorporated when computing the model of the outer ear. A pair of second order polynomials were used to create a new radius-length function which approximates the relationship between the radius of the auditory canal and its length. The frequency response of the outer ear model obtained using the radius-length function gave a wide frequency range representation of the outer ear characteristics. The middle ear is modelled using an analog network. Only the linear operation region of the middle ear was considered, thus excluding its reflex nonlinear mechanisms, namely; the stapedius muscle action and the stapes clipping displacement. The influence of the middle ear on the transmission of OAEs was evaluated by considering both the forward and reverse transmission characteristics/path of the middle ear. The middle ear response demonstrated great sensitivity to changes in the terminal loads connected to the middle ear as well as the transformer ratio. The inner ear behavior is represented by means of a nonlinear transmission line model. The nonlinear mechanism of the outer hair cells, which are taken as the primary sources of OAEs, are modelled using nonlinear voltage sources. The inner ear model was evaluated for conditions of both the active and inactive outer hair cells voltage sources. Due to limitations in the simulation software, a reduced active inner ear model was computed.The influence of the number of segments of the inner ear was explored. A reduced inner ear model having 40 segments was found to be sufficient in representing the frequency characteristics of the inner ear, whilst preserving the frequency-latency relationship of OAEs. The study not only improved the model of the auditory periphery, but also suggested several factors that can be incorporated in future research in order to better design signal acquisition and processing methods for OAE biometric applications.