Includes bibliographical references (8 p.) / ix, 173, [8] p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines some of the consequences of the acceleration and production, and propagation, of high energy electrons and positrons in the Galaxy. In particular, predictions are made of the diffuse photon signals arising from the interactions of electrons and positrons with gas, low energy photons, and the galactic magnetic field during their transport in the Galaxy. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1999

Bibliography: leaves 209-254. / viii, 254, [39] leaves, [17] leaves of plates : ill. 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Attempts to construct an evolutionary overview of the regulation of surfactant secretion among the vertebrates. A detailed whole animal and in vitro study of the factors that control surfactant secretion and function in the central Australian agamid lizard Pogona vitticeps was undertaken. Type II pneumocytes were also isolated and cultured from Australian lungfish, North American bullfrogs and fat-tailed dunnarts. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physiology, 1999

Includes bibliographical references (8 p.) / ix, 173, [8] p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines some of the consequences of the acceleration and production, and propagation, of high energy electrons and positrons in the Galaxy. In particular, predictions are made of the diffuse photon signals arising from the interactions of electrons and positrons with gas, low energy photons, and the galactic magnetic field during their transport in the Galaxy. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1999

The need to attenuate noise transmitted into enclosed spaces such as aircraft cabins, automobiles and mining cabins has provided the impetus for many active noise control studies. Studies into active interior noise control began with a pressure squared cost function utilising multiple error sensors and control sources in an attempt to produce global control of the interior sound field. This work found problems with observability of the primary disturbances and a large number of error sensors and control sources were required to produce global control. Since this early work in the 1980's, many new acoustic based cost functions have been developed to improve on the performance of the pressure squared cost function. This thesis will focus on one novel acoustic cost function, virtual error sensing. Virtual error sensing is a relatively new technique which produces localised zones of attenuation at a location remote to the physical sensors. The practical advantage of this method is the people within these enclosed spaces are able to observe a reduction in sound pressure level without their movement being restricted by error sensors located close to their ears. The aim of this thesis is to further investigate the performance of forward-difference virtual error sensors in order to understand the factors that affect the accuracy of the pressure prediction at the virtual location and use this information to develop more accurate and efficient forward- difference virtual sensors. These virtual sensors use linear arrays of microphones containing two or more microphone elements and a linear or quadratic approximation is used to predict the sound at the virtual location. The prediction method determines the weights applied to each microphone signal to predict the sound pressure level at the virtual location. This study investigates susceptibility of the sensors to corruption as a result of phase and sensitivity mismatch between the microphones, as well as in the location of the elements in the error sensing array. A thorough error analysis of the forward-difference virtual microphones was performed in a one-dimensional sound field and in a plane wave sound field. The accuracy of the quadratic virtual microphone was found to be strongly affected by the presence of short wavelength extraneous noise. From this study, two novel virtual error sensing techniques were developed, namely; higher-order virtual sensors and adaptive virtual sensors. The higher-order virtual error sensors still employ the linear and quadratic prediction method but extra microphone elements are added to the array. The aim of these higher-order virtual microphones is to produce a more accurate prediction of the pressure at the virtual location by spatially filtering out any short wavelength extraneous noise that may corrupt the prediction. These virtual sensors were tested in a realtime control scenario in both a one-dimensional reactive sound field and in a free field. This work found that the higher-order virtual microphones can improve the prediction accuracy of the original virtual sensors but are still prone to problems of phase, sensitivity and position errors. Finally, the adaptive LMS virtual sensors were investigated in a SIMULINK simulation and tested experimentally using real-time control in a one-dimensional sound field. It was hoped that an adaptive LMS algorithm could overcome previous difficulties arising from inherent and transducer errors by adapting the weights of the signals from the sensing elements which form the array. The algorithm adapts the sensing microphone signals to produce the same signal as the microphone at the virtual location. Once this has been achieved, the sensing microphone weights are fixed and the microphone at the virtual location is removed, thus creating a virtual microphone. The SIMULINK simulation allowed the performance of the fixed weight and virtual microphones to be investigated in the presence of only phase errors, sensitivity errors and position errors and in the presence of all three combined. This work showed that the adaptive virtual sensors had the ability to compensate for the errors. The number of modes used in the simulations was varied to observe the performance of all virtual sensors in the presence of higher-order modes. The prediction accuracy of the fixed weight virtual sensors was found to be greatly affected by the presence of higher-order modes. The use of the adaptive virtual microphones to produce localised zones of quiet was examined experimentally using real-time control. The study found the real-time control performance is superior to that of the fixed weight higher-order virtual microphones and the original forward-difference virtual microphones. / Thesis (Ph.D.)--School of Mechanical Engineering, 2003.

Large electric transformers such as those used in high voltage substations radiate an annoying low frequency hum into nearby communities. Attempts have been made to actively control the noise by placing a large number of loudspeakers as control sources around noisy transformers to cancel the hum. These cancellation systems require a large number of loudspeakers to be successful due to the imposing size of the transformer structures. Thus such systems are very expensive if global noise reduction is to be achieved. The aim of this thesis is to investigate theoretically and experimentally the use of thin perforated panels closely placed to a heavy structure to reduce the radiation of unwanted harmonic noise. These panels can themselves be vibrated to form a control source radiating over a large surface surrounding the primary source. The problem of the equipment overheating inside the enclosure is alleviated because the holes in the panels still allow natural cooling. An initial study is carried out to determine the resonance frequencies of perforated panels. The use of previously determined effective elastic properties of the panels and Finite Element Analysis to theoretically calculate their resonance frequencies is examined. Secondly the attenuation provided by active noise control using perforated panels as control sources is explored by use of a coupled analysis, where the primary source is assumed to influence the radiation of the perforated control panel. This analysis was found to predict poorly the amount of attenuation that could be achieved, so an uncoupled analysis is undertaken, where both the primary and control sources are assumed to radiate independently of each other. Not only does this greatly simplify the theoretical analysis but it also enables prediction of attenuation levels which are comparable to those determined experimentally. The theoretical model is reformulated to enable comparison of the sound power attenuation provided by perforated panel control sources with that of traditional acoustic and structural control sources. Finally, the use of modal filtering of traditional acoustic error sensor signals to give transformed mode (or power mode) sensors is examined. The independently radiating acoustic transformed modes of the panel are determined by an eigenanalysis and a theoretical analysis is presented for a farfield acoustic power sensor system to provide a direct measurement of the total radiated acoustic power. The frequency dependence of the sensor system, and the amount of global sound power attenuation that can be achieved is examined. Experimental measurements are made to verify the theoretical model and show that a sound power sensor implemented with acoustic sensors can be used in a practical active noise control system to increase the amount of attenuation that can be achieved. Alternatively the sound power sensor can be used to reduce the number of error channels required by a control system to obtain a given level of attenuation when compared to traditional error criteria. The power mode sensor analysis is then applied to the perforated panel control system, with similar results. / Thesis (Ph.D.)--Engineering (Department of Mechanical Engineering), 1996.

Large electric transformers such as those used in high voltage substations radiate an annoying low frequency hum into nearby communities. Attempts have been made to actively control the noise by placing a large number of loudspeakers as control sources around noisy transformers to cancel the hum. These cancellation systems require a large number of loudspeakers to be successful due to the imposing size of the transformer structures. Thus such systems are very expensive if global noise reduction is to be achieved. The aim of this thesis is to investigate theoretically and experimentally the use of thin perforated panels closely placed to a heavy structure to reduce the radiation of unwanted harmonic noise. These panels can themselves be vibrated to form a control source radiating over a large surface surrounding the primary source. The problem of the equipment overheating inside the enclosure is alleviated because the holes in the panels still allow natural cooling. An initial study is carried out to determine the resonance frequencies of perforated panels. The use of previously determined effective elastic properties of the panels and Finite Element Analysis to theoretically calculate their resonance frequencies is examined. Secondly the attenuation provided by active noise control using perforated panels as control sources is explored by use of a coupled analysis, where the primary source is assumed to influence the radiation of the perforated control panel. This analysis was found to predict poorly the amount of attenuation that could be achieved, so an uncoupled analysis is undertaken, where both the primary and control sources are assumed to radiate independently of each other. Not only does this greatly simplify the theoretical analysis but it also enables prediction of attenuation levels which are comparable to those determined experimentally. The theoretical model is reformulated to enable comparison of the sound power attenuation provided by perforated panel control sources with that of traditional acoustic and structural control sources. Finally, the use of modal filtering of traditional acoustic error sensor signals to give transformed mode (or power mode) sensors is examined. The independently radiating acoustic transformed modes of the panel are determined by an eigenanalysis and a theoretical analysis is presented for a farfield acoustic power sensor system to provide a direct measurement of the total radiated acoustic power. The frequency dependence of the sensor system, and the amount of global sound power attenuation that can be achieved is examined. Experimental measurements are made to verify the theoretical model and show that a sound power sensor implemented with acoustic sensors can be used in a practical active noise control system to increase the amount of attenuation that can be achieved. Alternatively the sound power sensor can be used to reduce the number of error channels required by a control system to obtain a given level of attenuation when compared to traditional error criteria. The power mode sensor analysis is then applied to the perforated panel control system, with similar results. / Thesis (Ph.D.)--Engineering (Department of Mechanical Engineering), 1996.

The Waipara – Kowai groundwater allocation zones (referred to as zones) are located 50 kilometers north of Christchurch. Land use in the Waipara zone has evolved from dry land farming towards horticultural and irrigated pastoral farming, and as such the demand for groundwater resources has increased significantly. Recent 14C age dating has shown that deep wells tap >1000 years old water, raising concerns about possible resource mining. The Kowai groundwater allocation zone has had minimal regional hydrogeological investigations and previously little is known about the groundwater resources here. The Waipara – Kowai groundwater allocation zones are located near obliquely convergent plate margin and the Porters Pass Fault System. Recent (early Quaternary) deformation has been noted by workers along margins and associated with emerging structures within basins. These emerging faults and folds within the basin are acting as hydrological barriers, hindering the passage of groundwater within the basin. A geomorphic map was constructed for this study based on existing soils maps, limited field soil surveys and morphometric analysis. Nine geomorphic surfaces are described, with inferred ages of modern to >73 ka. The geomorphic investigation revealed that the Kowai groundwater allocation zone surface is stepped, with increasing thickness of loess up gradient on the downlands. Near the coast there is intercalated terrestrial and marine sediments, to the west overlying the Kowai Formation are small alluvial fans. In the Waipara Basin the Waipara fan dominates the central portion of the basin, with smaller fluvial and alluvial fans building out from the margins. Groundwater recharge was investigated using chemical, isotopic, water level observations and a simple water balance. It was found that in the Kowai zone the major recharge sources were the rainfall, losses from the rivers and streams. The southern region of the Waipara zone is recharged by rainfall with small contributions from the Kowai River (North Branch). In the South region of the Waipara Basin groundwater recharge is derived from rainfall and losses from streams. The groundwater systems are conceptualized as being topographically driven, with slope – basin floors interactions being an important source of groundwater recharge.

This thesis develops image segmentation methods for the application of automated cervical cancer screening. The traditional approach to automating this task has been to emulate the human method of screening, where every one of the hundreds of thousands of cells on each slide is analysed for abnormality. However, due to the complexity of cervical smear images and the low error tolerance imposed upon the segmentation stage, only limited success has previously been found. A different approach is to detect malignancy associated changes (MACs) in a relatively small sample of the total population of cells. Under this paradigm, the requirement to segment every cell is loosened, but delineation accuracy and error checking become essential. Following a review of generic and cervical smear segmentation, it is concluded that prior work on the traditional approach to automation is not suitable for a MACs solution. However, the previously proposed framework of a dual-magnification system is found to be relevant and is therefore adopted. Here, scene images are first captured at low resolution in order to rapidly locate the cells on a slide. Cells that are deemed to be suitable for further analysis are then imaged at high resolution for the more accurate segmentation of their nuclei. A water immersion algorithm is developed for low resolution scene segmentation. This method achieves a rapid and robust initial segmentation of the scene without the requirement of incorporating extensive a priori knowledge of the image objects. A global minimum searching contour is presented as a top-down method for segmenting the high resolution cell nucleus images where the image objects are well characterised by shape and appearance. This latter method is tested upon 20,000 images and found to achieve an accurate segmentation rate of 99.47%. An error checking method, that uses segmentation stability as an indicator of segmentation success, is developed that is capable of detecting 100% of the failures of the nucleus segmenter, at the expense of discarding only 9% of the data. Throughout this work, contemporary issues in the field of generic image segmentation are presented and some of these are addressed for the cervical smear application. Finally, an avenue of future work is proposed which may lead to the much wider proliferation of computer vision solutions to everyday problems.

Thesis (Ph. D.)--George Mason University, 2007. / Title from PDF t.p. (viewed Jan. 17, 2008). Thesis director: Shobita Satyapal. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physical Sciences. Vita: p. 217. Includes bibliographical references (p. 202-216). Also available in print.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 108-114).