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Multiscale modelling of snow depth over an agricultural field in a small catchement in southern ontario, canada.Neilly, R. Michael A. January 2011 (has links)
Snow is a common overlying surface during winter-time and the redistribution of snow by wind is a very important concept for any hydrological research project located within the cryosphere. Wind redistributes snow by eroding it from areas of high wind speed, such as ridge tops and windward slopes, and deposits it in areas of lower wind speeds, such as the lees of ridge tops, vegetation stands, and topographic depressions. The accurate modelling of blowing snow processes such as erosion, deposition, and sublimation have proven to be rather problematic. The largest issue that many modellers must deal with is the accurate collection of solid precipitation throughout the winter season. Without this, incorrect energy and mass balances can occur. This thesis makes use of a new method of acquiring solid precipitation values through the use of an SR50a ultrasonic snow depth sensor and then incorporates it into a version of the Cold Regions Hydrological Model (CRHM) which includes the Prairie Blowing Snow Model (PBSM) and the Minimal Snowmelt Model (MSM) modules. The model is used to simulate seasonal snow depth over an agricultural field in southern Ontario, Canada and is driven with half-hourly locally acquired meteorological data for 83 days during the 2008-2009 winter season. Semi-automated snow surveys are conducted throughout the winter season and the collected in situ snow depth values are compared to the simulated snow depth values at multiple scales. Two modelling approaches are taken to temporally and spatially test model performance. A lumped approach tests the model‟s ability to simulate snow depth from a small point scale and from a larger field scale. A distributed approach separates the entire field site into three hydrological response units (HRUs) and tests the model‟s ability to spatially discretize at the field scale. HRUs are differentiated by varying vegetation heights throughout the field site. Temporal analysis compares the simulated results to each day of snow survey and for the entire field season. Model performance is statistically analyzed through the use of a Root Mean Square Difference (RMSD), Nash-Sutcliffe coefficient (NS), and Model Bias (MB). Both the lumped and distributed modelling approaches fail to simulate the early on-set of snow but once the snow-holding capacities are reached within the field site the model does well to simulate the average snow depth during the latter few days of snow survey as well as throughout the entire field season. Several model limitations are present which prevent the model from incorporating the scaling effects of topography, vegetation, and man-made objects as well as the effects from certain energy fluxes. These limitations are discussed further.
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A study through text and artifacts of the major factors that have influenced the development of studio glassmaking in South Australia from a glassmaker's perspective : history and practice of studio glass blowing in South AustraliaCowie, Barbara Jane January 2004 (has links)
Although many texts discuss studio glass blowing in Australia, few focus on the South Australian situation and even fewer are written by studio glass blowers themselves. As a studio glass blower, I bring to this research experiential knowledge of practice to offer new insights into studio glass blowing. The study accesses knowledge that is implicit, embodied and tacit; knowledge derived from living and working within a particular community. In using this knowledge, I highlight the importance of both financial survival and the development of practice in creating a practitioner's perspective of studio glass blowing in South Australia. The study is designed as an ethnography. This incorporated a review of the literature and images found in published texts; interview and questionnaire data; anecdotal narratives and familiarity with the South Australian glass blowing community; and tacit knowledge of glass blowing practice, glass blowing skills and techniques. This tacit knowledge was accessed through an auto-ethnographic investigation of re-making the selected artefacts. The selection of these artefacts was based on my personal knowledge of glass blowing processes, first hand relationships with individual glassblowers, observation of artefacts and prior experience of working as a studio glass blower.
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The effects of reputation threat and whistle-blowing report source on chief audit executives' investigation decisionsGuthrie, Cynthia Peterson, January 1900 (has links)
Thesis (Ph.D.)--Virginia Commonwealth University, 2008. / Prepared for: Dept. of Accounting. Title from title-page of electronic thesis. Bibliography: leaves 142-149.
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An interaction in glass /Berg, Jason. January 1995 (has links)
Thesis (M.F.A.)--Rochester Institute of Technology, 1995. / Typescript. Includes bibliographical references (leaf [9]).
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Research into lead glass /Applebaum, S. Leon. January 1981 (has links)
Thesis (M.F.A.)--Rochester Institute of Technology, 1981. / Typescript. Includes bibliographical references (leaf 28).
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Glass in a slump /Andres, Peter V. January 1984 (has links)
Thesis (M.F.A.)--Rochester Institute of Technology, 1984. / Typescript. Includes bibliographical references.
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Towards a sociological understanding of the relationship between job satisfaction and whistleblowingRobinson, Raymond William 17 November 2010 (has links)
M.A. / Whistleblowing can be defined as the disclosure by organisation members (former or current) of illegal, immoral or illegitimate practices under the control of their employers, to persons or organisations that may be able to effect action. There are various factors that influence the extent to which people would be prepared to blow the whistle. One of these factors is job satisfaction. The extent to which people are satisfied in their jobs influences the extent to which the whistle will be blown. However, the relationship between whistleblowing and job satisfaction has not been studied in great detail and not at all in a South African context. The nature of this relationship was explored among academic staff at a South African university by means of a quantitative study. It was decided to conduct the study at the Auckland Park Kingsway Campus (APK) of the University of Johannesburg (UJ) due to the degree of transformation that has taken place at this institution in recent years and thus being relevant regarding the issue of job satisfaction. The study involved investigating the circumstances under which academic staff would be prepared to blow the whistle, how far they would be prepared to go in terms of making use of various channels to report wrongdoing, the level of job satisfaction, as well as the relationship between job satisfaction and the responses of academic staff members to whistleblowing. Examination of the findings revealed that overall the academic staff of the University of Johannesburg are satisfied in their jobs and this correlated, to a small degree, with the furthest reporting of offences that are minor in nature. Overall, academic staff were more inclined to report wrongdoing internally. Academic staff who had been employed at the university for more than ten years as well as those who had no financial dependants were slightly more inclined to report wrongdoing than those who had been employed for a shorter period of time and had financial dependants.
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Reduction of Unsteady Rotor-Stator Interaction Using Trailing Edge BlowingLeitch, Thomas A. 16 January 1997 (has links)
An aeroacoustic investigation was performed to assess the effects of adding mass flow at the trailing edges of four stators upstream of an aircraft engine simulator. By using trailing edge blowing to minimize the shed wakes of the stators, the flow into the rotor was made more uniform. In these experiments a reduced number of stators (four) was used in a 1/14 scale model inlet which was coupled to a 4.1 in (10.4 cm) turbofan engine simulator with 18 rotors and 26 downstream stators. This study is a preliminary step toward a more in depth investigation of using trailing edge blowing to reduce unsteady rotor-stator interaction. Steady-state measurements of the aerodynamic flow field and acoustic far field were made in order to evaluate the aeroacoustic performance at three simulator speeds: 40%, 60%, and 88% of the design speed. The lowest test speed of 40% design speed showed the most dramatic reduction in radiated noise. Noise reductions as large as 8.9 dB in the blade passing tone were recorded at 40% design speed, while a tone reduction of 5.5 dB was recorded at 60% design speed. At 88% design speed a maximum tone reduction of 2.6 dB was recorded. In addition, trailing edge blowing reduced the overall sound pressure level in every case. For both the 40% design speed and the 60% design speed, the fan face distortion was significantly reduced due to the trailing edge blowing. The addition of trailing edge blowing from the four upstream stators did not change the total pressure ratio, and the mass flow added by the blowing was approximately 1%. The results of these experiments clearly demonstrate that blowing from the trailing edges of the stators is effective in reducing unsteady rotor-stator interaction and the subsequent forward radiated noise. / Master of Science
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A Conceptual Design Methodology for Predicting the Aerodynamics of Upper Surface Blowing on Airfoils and WingsKeen, Ernest Brock 15 December 2004 (has links)
One of the most promising powered-lift concepts is Upper Surface Blowing (USB), where the engines are placed above the wing and the engine exhaust jet becomes attached to the upper surface. The jet thrust can then be vectored by use of the trailing edge curvature since the jet flow tends to remain attached by the "Coanda Effect". Wind tunnel and flight-testing have shown USB aircraft to be capable of producing maximum lift coefficients near 10. They have the additional benefit of shielding the engine noise above the wing and away from the ground.
Given the potential gains from USB aircraft, one would expect that conceptual design methods exist for their development. This is not the case however. While relatively complex solutions are available, there is currently no adequate low-fidelity methodology for the conceptual and preliminary design of USB or USB/distributed propulsion aircraft. The focus of the current work is to provide such a methodology for conceptual design of USB aircraft. Based on limited experimental data, the new methodology is shown to compare well with wind tunnel data.
In this thesis we have described the new approach, correlated it with available 2-D data, and presented comparisons of our predictions with published USB data and an existing non-linear vortex lattice method. The current approach has been shown to produce good results over a broad range of propulsion system parameters, wing geometries, and flap deflections. In addition, the semi-analytical nature of the methodology will lend itself well to aircraft design programs/optimizers such as ACSYNT. These factors make the current method a useful tool for the design of USB and USB/distributed propulsion aircraft. / Master of Science
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Reduction of Unsteady Stator-Rotor Interaction by Trailing Edge Blowing Using MEMS Based MicrovalvesRao, Nikhil M. 30 April 1999 (has links)
This research performs an experimental study of a trailing edge blowing system that can adapt to variations in flow parameters and reduce the unsteady stator-rotor interaction at all engine operating conditions. The fan rotor of a 1/14 scale turbofan propulsion simulator is subjected to spatially periodic, circumferential inlet flow distortions. The distortions are generated by four struts that support a centerbody in the inlet mounted onto the simulator. To reduce the unsteady effects of the strut wakes on the rotor blades, the wake is re-energized by injecting mass from the trailing edge of the strut. Each strut is provided with discrete blowing holes that open out through the strut trailing edge. Each blowing hole is connected to a MEMS based microvalve, which controls the blowing rate of the hole. The microvalve is actuated by a signal voltage, generated by a PID controller that accepts free stream and wake axial flow velocities as inputs and minimizes their difference. To quantify the effectiveness of trailing edge blowing the far-field noise is measured in an anechoic chamber. The experiments are performed for two simulator test speeds, 29,500 rpm and 40,000 rpm, with and without trailing edge blowing. The maximum reduction recorded at 29,500 rpm is 8.2 dB, and at 40,000 rpm is 7.3 dB. Reductions of 2.9 dB and greater are observed at the first five harmonics of the blade passing frequency. The sound power level at the blade passing frequency, calculated from measured far-field directivity, is reduced by 4.4 dB at 29,500 rpm and by 2.9 dB at 40,000 rpm. The feasibility and advantage of active control is demonstrated by the ability of the system to respond to a step change in the inlet flow velocity, and achieve optimum wake filling in approximately 8 seconds. / Master of Science
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