Thesis (M.S.)--University of Michigan, 1978.

Thesis (M.S. in Operations Research)--Naval Postgraduate School, September 1992. / Thesis Advisor: Rosenthal, Richard E. "September 1992." Description based on title screen as viewed on March 10, 2009. Includes bibliographical references (p. 55). Also available in print.

Thesis (Ph. D.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: John C. Priscu. Includes bibliographical references (leaves 181-201).

No description available.

The guided wave technique is an ultrasonic technique which is used to monitor large structures in a variety of industry sectors to safeguard against catastrophic failure. The guided wave technique for pipeline inspection has been commercially used since the early 2000s and this facilitates rapid inspection where from a single location over 100 metres of pipeline can be inspected. This technique is currently being used in pipeline infrastructure across the globe. For the technique to be successful it is highly dependent on a numerous of factors including, frequency selection, array designs and pipeline geometries. The transducers used on pipeline are dry coupled and the magnitude of the signal transmitted is dependent on the normal force applied to it. If this force is not controlled the signal being transmitted can degrade and lead to the difficult analysis of a complex signal. In this thesis studies have been undertaken to understand the relationship between dry force coupling of the transducer and the signal received, aligning this connection to classical contact theory. This is then further to extended to the influence surface contact conditions have on the transmission of signal from the transducer. Analysis of the results detected a peak in the operational frequency response which in turn initiated electrical impedance and structural resonance measurements to identify the presence of resonances which are induced by dry coupling. This behaviour was then modelled in FEA software and the validity of the FEA approach was tested against several prototype transducers. This thesis has been funded in joint collaboration between the Engineering Physics and Science Research Council and TWI ltd.

M.Sc. (Biochemistry) / Dry eye disease (DED) and keratoconus (KC) continue to affect the quality of life of many South Africans (and elsewhere) and in the case of KC often leads to blindness. It is estimated that DED affects 14% to 33% of the population worldwide, while 1 in 2000 of the worlds population is affected by KC. However, details of the etiology of these diseases and their biochemical ‘fingerprint’ remain uncertain. In this study, emphasis was placed on the investigation of immunological proteins in the precorneal tear film of DED and KC subjects and meibomian lipids in these individuals. Tear fluid and meibum were collected from control, DED and KC volunteers. Control subjects were non-contact lens wearers and free from ocular diseases, whereas DED subjects were diagnosed by means of an ocular surface disease index (OSDI) questionnaire. DED subjects were divided into two groups: ‘moderate DED’ and ‘severe DED’ based on OSDI. KC subjects were diagnosed by the use of a slit-lamp biomicroscopy exam. Enzymelinked immunosorbent assays were performed to quantitate secretory immunoglobulin A (sIgA), tumour necrosis factor-alpha (TNF-á) and matrix metalloproteinase-1 (MMP-1) in the collected tear fluid. Meibum was analysed with proton nuclear magnetic resonance (1H-NMR) spectroscopy and Fourier transform infrared spectroscopy (FTIR). Multivariate data analyses (PCA) were used to extract interpretable information from the multidimensional data generated from the aforementioned techniques and used to build a broad picture of the general lipidomic differences between DED, KC and healthy subjects. Tear levels of sIgA and MMP-1 were significantly decreased in patients with KC compared to control. In contrast, the tears of severe DED subjects were characterised by higher levels of TNF-á and lower levels of sIgA. In subjects with moderate DED, TNF-á levels were significantly elevated. The results of this study re-emphasize that KC and DED individuals are associated with differential expression of specific tear proteins and support the view that the severity of DED is reflected in the levels of immunological proteins present in basal tears. Differences in the chemical composition of meibum from subjects with severe DED and KC compared to control were observed, more specifically in the aliphatic region of 1H-NMR spectra and C-C rocking region of FTIR spectra. The results therefore point towards the saturated components of fatty acids (and their chemical environments) as key targets for future investigations to elucidate compositional differences between DED, KC and healthy meibum.

The aim of this study was to evaluate the methane potential of 35 kg of blue mussels in a batch amanaerobic two-stage dry digestion system (pilot-scale), which consists of aleach bed reactor (LB) and an up-flow anaerobic sludge blanket reactor (UASB). We monitored the process daily by measuring temperature, pH, COD, VFA, NH4+ gas flow rate and gas content. The temperature was approximately 30 C in the LB and 36 C in the UASB reactor. The applied OLR was 1.5 g COD/l*d. After 37 days process run, we obtained a total methamne yield of 0.64 Nm3 respectively 0.29 Nm3/kg VS, of that 70% in the LB reactor and 30% in the UASB reactor.

In this work the performance of cerium-based oxygen carriers is investigated in a simulated chemical looping dry reforming system using methane and carbon dioxide as fuel and oxidizing gas respectively. The samples to be studied are pure cerium oxide and cerium oxide doped with zirconium, yttrium, samarium, and scandium more specifically: CeO2, Ce0.8Y0.2O1.9, Ce0.85Y0.05Zr0.1O1.975, Ce0.95Zr0.05O2, Ce0.9Sm0.05Zr0.05O1.975, and Ce0.9Sc0.05Zr0.05O1.975. Characteristics such as crystallography including lattice parameter and particle size of the samples are evaluated using X-ray diffraction (XRD) and particle size analysis. The oxygen transport capacity will also be measured using a thermogravimetric analyzer (TGA). This method of measurement also allowed for insight on oxygen release temperatures as well as recyclability of the samples. The particle size analysis showed that the synthesis method of precipitation-agglomeration resulted in samples with consistent particle size distribution indicating the method can be scaled up. The X-ray analysis of samples before and after the TGA tests show that all the materials tested had a cubic fluorite crystal structure which was maintained through the oxidation reduction cycles. The lattice parameter was found to increase slightly with a loss in oxygen content in the samples. The addition of trivalent dopants resulted in a decrease in the temperature of initiation of reduction in methane. While reduction of commercial ceria initiated near 800 oC. the addition of trivalent dopants resulted in a lowering of the initialization temperature between of 150 – 200oC. The activation energy of commercial ceria was 248.42 kJ/mol for reduction in methane, indicating that the rate controlling mechanism is chemical reaction rather than diffusion. The addition of trivalent dopants resulted in a significant lowering in the activation energy. The activation energies obtained in this study show that the addition of dopant increased the significance of diffusion through the solid and the controlling mechanisms were both diffusion and chemical reaction. Overall, the addition of trivalent dopants enhanced the extent of oxygen exchange in CLDR process.

Lubrication is used during the drilling of aluminum to counter the formation of a built-up-edge (BUE), among other reasons. The elimination of the use of lubricants in drilling of aluminum is important because of the associated high costs of cleaning and disassembly involved in lubrication. The optimal conditions sought in this work include the elimination of the use of lubricants along with the possible attainment of a high material removal rate, which could help in reduction of cost and increase productivity at the same time. BUE has been found to be almost always present in the process of metal cutting at low to moderate speeds. It has been found that a necessary condition for the formation of a BUE is the presence of a negative stress gradient away and normal to the tool rake face. The quantitative equivalence of the effects of temperature and strain rate on flow stress described by the Zener-Hollomon parameter (Z) [5]. The relationship between the Zener-Hollomon parameter (Z) and chip flow stress implies that a negative Z gradient could be considered equivalent to a negative stress gradient. A series of computer simulations with varied cutting conditions were analyzed to determine the combination of machining variables which yielded a low predicted BUE preferably with a high material removal rate. The results presented here include cases which have a low predicted BUE as well as a high material removal rate.

PURPOSE: Age-related macular degeneration (AMD) is a complex, progressive ocular disorder that results in outer retinal ischemia and severe vision loss. Dry AMD, the most common form of AMD, is characterized by the build-up of extracellular drusen deposits, dysfunction of the outer retinal layers and degeneration of photoreceptors. This study aimed to examine the anatomic and physiologic effects of short-term normobaric hyperoxia in patients at different stages of dry AMD. METHODS: Twenty-two eyes from 16 patients diagnosed with dry AMD (11 females, 5 males) were used in this study. Eyes were categorized as having either small drusen or drusenoid pigment epithelial detachments (DPEDs) through optical coherence tomography (OCT) imaging. Eyes associated with small drusen received 3-hours of 40% fraction of inspired oxygen (FiO2) normobaric hyperoxia (NBH), whereas eyes associated with DPEDs received either 3-hour NBH or 3-hours of 20% FiO2 normobaric normoxia (NBN). Visual acuity and OCT images of the macula were taken before and after oxygen treatment. Anatomic outcomes consisted of foveal thickness, foveal volume, macular volume and maximum drusen height; visual acuity was the functional outcome. The relationship between maximum drusen height and visual acuity was then examined to determine if these outcomes were associated. RESULTS: Eyes associated with DPED treated with 3-hour NBH had the largest decreases in foveal thickness, foveal volume, macular volume and maximum drusen height. The macular layers were then divided into inner and outer layers. The outer layers, comprised of Bruch’s membrane, drusen and the retinal pigment epithelium, had significant decreases in anatomic outcomes, whereas the inner layers showed no changes. DPED patients treated with 3-hour NBH also had the largest increase in visual acuity following treatment. There was a significant negative correlation between baseline drusen height and baseline visual acuity. For patients with small drusen treated with 3-hour NBH, there were no significant changes to anatomic or functional outcomes. CONCLUSION: The current study demonstrates the efficacy of short-term administration of normobaric hyperoxia in high-risk dry AMD patients with associated DPEDs. Normobaric hyperoxia appears to be a novel and promising treatment that requires further investigation.