Obtaining higher depth of imaging is an important goal in Optical Coherence Tomography (OCT) systems. One of the main factors that affect the depth of OCT imaging is the presence of noise. That’s why the study of noise statistics is an important problem. In the first part of this thesis we obtain an empirical estimate of the second order statistics of noise by using a sequence of Time domain (TD) OCT images. These estimates confirm the non-stationary nature of noise in TD-OCT. In the second part of the thesis these estimates are used to design a depth-dependent matched filter to maximize the Signal-to-Noise Ratio (SNR) and increase the Contrast-to-Noise Ratio (CNR) in TD-OCT. By applying our filter to TD-OCT images of both vascular rabbit tissue and a human tooth, both SNR and CNR were increased and a higher imaging depth was achieved.

Due to more and more aggressive designs in turbomachinery, assuring the structural integrity of its components has become challenging. Also influenced by this trend is blade design, where lighter and slimmer blades, in combination with higher loading, lead to an increased risk of failure, e.g. in the form of blade vibration. Methods have been proposed to reduce vibration amplitudes for subsonic engines, but cannot directly be applied to transonic regimes due to the additional physical phenomena involved. Therefore the present work investigates numerically the influence of two methods for reducing blade vibration amplitudes in transonic turbomachines, namely varying the blade count ratio and clocking. As it is known that clocking affects the efficiency, the concurrent effects on vibration amplitudes and efficiency are analyzed and discussed in detail. For the computational investigations, the proprietary Fortran-based non-linear, viscous 3D-CFD solver VolSol is applied on two transonic compressor cases and one transonic turbine case. In order to reduce calculation time and to generate the different blade count ratios a scaling technique is applied. The first and main part of this work focuses on the influence of the reduction techniques on aerodynamic forcing. Both the change in blade count ratio and clocking position are found to have significant potential for reducing aerodynamic force amplitudes. Manipulation of the phasing of excitation sources is found herein to be a major contributor to the amplitude variation. The lowest stimulus results are achieved for de-phased excitation sources and results in multiple blade force peaks per blade passing. In the case of blade count ratio variation it was found that blockage for high blade count ratios and the change in potential field size have significant impacts on the blade forcing. For the clocking investigation, three additional operating points and blade count ratios are analyzed and prove to have an impact on the force reduction achievable by clocking. The second part of the work evaluates the influence of clocking on the efficiency of a transonic compressor. It is found that the efficiency can be increased, but the magnitude of the change and the optimal wake impingement location depend on the operating point. Moreover it is shown that optimal efficiency and aerodynamic forcing settings are not directly related. In order to approximate the range of changes of both parameters, an ellipse approximation is suggested. / <p>QC 20130911</p> / TURBOPOWER

Graduate

Multidirectional motion occurs in total knee replacements (TKR), is a major factor in ultra high molecular weight polyethylene (UHMWPE) wear and is a requirement for wear tester and simulators. There are three ways the femoral component can move relative to the tibial component; sliding, rolling and gliding and these are defined by the slide to roll ratio. Previous wear tester research has investigated the effects of multidirectional motion and slide to roll ratio, individually but not combined. The project aim was to design a machine that combined multidirectional motion with variable slide to roll ratio. A three station wear testing machine was designed and built featuring flexion extension, variable anterior posterior translation, variable internal external rotation and a 2KN load per station. The TKR was simplified to a cylinder on flat. Lubrication was 25% bovine serum and each station had its own recirculation system. A million cycle validation test was successfully carried out on non-irradiated UHMWPE samples using a slide to roll ratio of 1 : 0.5 and the mean wear rate was 14.7mg/10^6 cycles. Polished areas and scratches from 3rd body abrasion were observed. Magnification revealed a fine ripple pattern with a 1-2 micron periodicity. Ripples were randomly oriented, perpendicular to the primary direction of motion and a small number were running parallel to the primary direction of motion, indicative of rolling motion. The results from the validation study show that the knee joint wear tester is capable of producing wear rates and wear mechanisms similar to those observed in other wear testers and knee joint simulators and has met the aim of the project.

Sexual conflict occurs when individuals of one sex express traits that reduce the fitness of their mates. Males of many species harass females to gain copulations, which benefits males by increasing the number of offspring they sire but imposes energetic and opportunity costs on the females they harass. This thesis examined the fitness costs of sexual harassment to females, the energetic costs of mating to males, and the factors influencing the intensity of male competition for mates in the western mosquitofish Gambusia affinis. I quantified male and female behavior, four female fitness components (number of offspring per female, embryo number, growth, and survival), and an index of male body condition in response to changes in operational sex ratio (experiment 1) and male and female density (experiment 2). I found that a strong, negative effect of female density on female fitness overwhelmed any potential costs of male harassment, suggesting that ecological interactions between females may play a larger role in determining female fitness than conflict between the sexes. Agonistic chases and displays between males increased as the operational sex ratio increased (became male-biased), while the number of copulations males attempted decreased. This inverse relationship suggests a tradeoff between interfering with other males and attempting additional copulations with females. Increases in chases between males were largely due to changes in female density, but not male density, suggesting that the availability of females determines whether males escalate contests with other males. In contrast, the number of displays between males depended varied with male density but did not female density. This difference between chases and displays is likely due to their difference in function; chases are performed to prevent other males from mating while displays are used to assess male competitors. I did not detect any energetic cost of mating to males.

For contacting a virtual cylinder located near the centre of the experimental tank, 4 male Siamese fighting fish (Betta splendens) received food reinforcement on a fixed-ratio (FR) 6 schedule. Ten times per second a tracking system recorded, in 3 dimensions, the location of the fish in the experimental tank. For each fish, the number of responses per session, the 2 dimensional swimming patterns, and the response patterns as observed in cumulative response plots were analyzed in 4 experimental conditions. The experimental conditions were: (a) both a response-location stimulus and a response-feedback stimulus were present; (b) neither a response-location nor a response-feedback stimulus were present; (c) only a response-location stimulus was present; (d) only a response-feedback stimulus was present. After experiencing the conditions, 2 fish were exposed to extinction, first with only the response-location stimulus present and then with the addition of the response-feedback stimulus. The combination of the response-location and the response-feedback stimulus and the response-location stimulus alone resulted in the highest number of responses per session and swimming patterns more concentrated in and around the target response location. The absence of a response-location stimulus and a response-feedback stimulus resulted in fewer responses per session and swimming patterns more spread out than in the conditions where the response-location stimulus was present. The response-feedback stimulus alone produced patterns similar to the condition where neither stimuli were present. In neither condition was an FR break-and-run response pattern observed in the cumulative response plots. The addition of the feedback-stimulus to the extinction resulted in a temporary increase in responding for one fish, but not for the other. The results suggested that the response-location stimulus functioned as a discriminative stimulus and that the response-feedback stimulus functioned as a conditioned reinforcer when combined with the coin, though its role in the absence of the coin was less clear. The characteristics of the response topography and the variability in the location of the consumption response may have contributed to the lack of a break-and-run pattern under FR6 with fish.

Ratio analysis is a financial analysis technique used by the corporate sector and public colleges and universities. Private colleges and universities have been largely unsuccessful utilizing this technique because of the varied accounting techniques used by the private institutions. This study attempted a different technique. The controllers of five institutions were asked to meet and agree on definitions of categories necessary for completing ratio analysis.Ratios are useful as a tool for monitoring financial changes over time within one institution, comparing similar institutions one with another and evaluating institutions in better financial condition for use as goal ratios.The resultant model consisted of a data dictionary which contained the definitions the controllers had created and iteratively refined, a data spreadsheet which contained the numbers over a five year period matching the definitions, and a ratio spreadsheet which presented the 58 ratios for each institution over a five year period. The controllers, acting as an expert panel for the study, believed the results to be reliable because of their level of involvement in setting the definitions and supplying the numbers. Average ratios were also calculated using the data from all five institutions over all five years. All resulting spreadsheets are contained in their entirety in the dissertation. / Department of Educational Leadership

The dividend payout policy is a very debated topic, in this thesis the differences between Sweden and Vietnam will be examined. By examine two different countries with more or less the same landmass, but regarding economic, culture and politics they differ highly.   The purpose of this study was to determine whether there were a difference between the countries in dividend payout ratios, to see if the countries payout a high or a low dividend during the years 2005 to 2012. The second purpose was to examine if there was a significant differences in the movements in the markets. The third purpose was to examine how the two countries acted during the financial crisis, if the dividend payout ratio changed. This may tell how the policies in the two countries differ and how long term or short term the firms within the countries were planning and which kind of investors they are attracting. The data being used is collected historical data from firms with in each of the countries. The thesis follows a quantitative research method based on a deductive and an inductive approach. The research design is comparative for examination of two the countries data samples and for the purposes descriptive and explanatory studies have been done. In order to determine whether there is a relationship between the countries dividend payout ratio, the normality of the data sample have been examined, showing that the data were not normal distributed. Therefor the data were examined with a Mann- Whitney test and by a Kruskal- Wallis test.   The result indicates that there is a difference between the countries in dividend payout ratios in the case of Vietnam and Sweden under the years 2005 to 2012. Comparing countries together between the years to determine possible differences, the dividend payout ratio was insignificant in 2005 to 2008, but significant in the years 2009 to 2012. The examination of Vietnam and Sweden separately with years as factors the dividend payouts in Vietnam showed a significant difference but an insignificant result in Sweden during the year 2005 to 2008. Further, the results showed that there is a difference between the years in Sweden between 2009 to 2012 but no differences in Vietnam under the same years.

Membrane filtration is growing in popularity as a viable technology for drinking water treatment to meet high demand and regulatory requirements. While many improvements have been made to the technology in the past decade, fouling continues to be one of the major operational challenges associated with membranes as it increases operating costs and reduces membrane life. Fouling control typically requires some form of pre-treatment. Biofiltration is a ???green??? technique that can minimize chemical usage and waste during water treatment and is a relatively new application as a pre-treatment for membranes. Proteins and polysaccharides (biopolymers) have been found to contribute most to fouling of low pressure polymeric membranes. Biofiltration has recently been demonstrated as an effective pre-treatment method for reducing biopolymer-associated fouling of this type of membrane (Hall?? et al., 2009). Given that the concentration and composition of organic matter in water is variable, there is an opportunity to explore the applicability of this robust technology for different water types. The primary goals of this research were to assess the effectiveness of direct biofiltration in minimizing ultrafiltration polymeric (PVDF) membrane fouling and at the same time evaluate the biofilter development, biofilter performance based on organics removal potential, and the effect of phosphorus addition (as a nutrient) to the biofilter influent. A pilot-scale treatment train was constructed at the Technology Demonstration Facility at the Walkerton Clean Water Centre. It included two parallel dual media (sand/anthracite) biological filters (preceded by roughing filters), followed by an ultrafiltration membrane unit. Experiments were conducted using water from the Saugeen River (Ontario, Canada) whose primary form of carbon is humic material. The biofilters were allowed to acclimate and biofilter performance and organics removal were tested over a fourteen month period, the last four months of which were dedicated to phosphorus enhancement experiments. The membrane fouling experiments started seven months following the start-up of the biofilters, after confirmation of steady-state operation. Biofilter water samples were analyzed for natural organic matter constituents along with other water quality parameters, and biomass quantity and activity in the media were measured. Biomass activity in the biofilter media and biopolymer removal through the biofilter indicated a rapid acclimation period, and also demonstrated similar performance of the parallel biofilters during start-up and steady-state operation. The biofilters achieved 21% removal of the biopolymers on average following acclimation, while reduction of the humic fractions was not observed. A linear relationship between biopolymer removal and its concentration in the river water was observed (first-order process). Membrane fouling experiments were conducted using both untreated and biofiltered river water. The fouling rates were computed by monitoring changes in transmembrane pressure over time. Analysis of the samples with liquid chromatography-organic carbon detection confirmed the significant contribution of biopolymers to irreversible and reversible membrane fouling rates even when only present at low concentrations. During the phosphorus enhancement phase, two different phosphorus doses were fed into the influent of one of the parallel biofilters in order to achieve a target C:N:P ratio of roughly 100:10:1. Although initially (first month of the dosing period) an increase in the removal of dissolved organic carbon and ultraviolet-absorbance was observed in the phosphorus-enhanced biofilter, this was not sustained. Phosphorus addition did not affect biopolymer removal or biomass quantity and activity in the biofilter, and the membrane fouling experiments during this period did not show any significant effect of phosphorus addition.

Sign language interpreters (SLI) provide a vital service to the deaf community but also experience high levels of pain and suffer from career threatening musculoskeletal disorders. Balancing work and rest (recovery) may be a useful intervention to help address these concerns. This thesis addresses two specific questions, parsed out of a larger study seeking to determine ideal work to rest ratios for sign language interpreting. The aims of this specific body of work were to evaluate sign language interpreters (SLIs) perceptions of the mental and physical demands associated with different work to rest ratios; and, to measure kinematics during signing, comparing kinematic outcomes between novice and experienced SLIs and over time using the work to rest ratio that was perceived as the least demanding (as identified in aim 1). Nine novice and nine experienced interpreters participated in the study, each interpreting the same ten hours of a university level lecture, over the course of six visits to the laboratory. During each session interpreters worked (“hands in the air”) for 60 minutes, but used a different work to rest strategy in each session. These strategies ranged from 10-minute work, 10-minute rest, to 60 minutes of continuous work with no rest. During each session, participants were instrumented with motion capture and electromyography sensors while interpreting in a simulated working environment. In addition, SLIs were asked to provide feedback about their perceptions of the mental and physical demands associated with each session. The first study in this thesis reports on participant’s subjective feedback about the six different sessions (paper #1); where participants identified the 15-minute work to rest ratio as ideal. The second paper reports on kinematic data from this perceived ideal work to rest ratio (paper #2). Despite interpreting in a work to rest ratio that SLIs perceived as ideal, kinematic variables with known associations to injury risk (joint position, velocity, micro-breaks) readily exceeded reported thresholds. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2014-05-29 17:46:11.133