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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.


Greening, Andrea Captain 09 1900 (has links)
<p>This thesis explores the design, fabrication, and experimental application of a variety of all-fiber vibration sensors, based upon a Michelson interferometer design. These sensors can be used to detect vibration in the low frequency regime. It also provides motivation for its use as an inexpensive yet rugged sensor for use in the harsh environment of a steel hot mill as part of an overall preventative/predictive maintenance program since commercially available piezoelectric sensors currently in use have significant reliability problems.</p> <p>While this work did result in a device that could withstand the steel hot mill surroundings and detect low frequency vibrations, higher sensitivities are expected from further optimized devices.</p> / Master of Applied Science (MASc)


Cziraky, Adam 09 1900 (has links)
<p>CANDU reactors are of the heavy water moderated, pressure tube type. The core consists of several hundred horizontal fuel channels surrounded by a heavy water moderator. Fuel channels consist of a Zircaloy-2.5%Nb pressure tube enclosed within a Zircaloy-2 calandria tube. There is an annulus gas gap between the pressure tube and the calandria tube. Under extreme accident conditions such as a critical break Loss Of Coolant Accident (LOCA), the pressure tube may deform. If the fuel channel remains pressurized, the hot pressure tube can balloon into contact with the calandria tube.</p> <p>Thermal contact conductance between the pressure tube and calandria tube must be understood as it is a key factor in studying fuel channel integrity. Once PT-CT contact occurs, heat is transferred from the hot pressure tube to the relatively cool calandria tube. The heat flux to the calandria tube is a function of the temperatures of the two tubes as well as the thermal contact conductance between them. For high heat flux levels the calandria tube temperature can increase enough for film boiling to occur on the outer surface. Film boiling will severely limit heat transfer to the moderator and cause overheating of the calandria tube which could lead to fuel channel failure. It is therefore important to understand the mechanisms involyed in thermal contact conductance and to study the transient behaviour of contact conductance during a PT-CT contact event.</p> <p>This paper presents a new approach to calculating the contact conductance transient during the initial contact and post-contact phases of a postulated critical break loss of coolant accident .The contact pressure at the interface between the tubes is a critical parameter in determining the thermal contact conductance. An iterative method is used to solve for creep strain in the pressure tube and calandria tube which determines the interfacial pressure. A modern correlation for contact conductance is then applied. The results show high contact conductance at first contact in the initial contact phase. This is followed by a rapid decrease in conductance across the interface. These results are due to the interfacial pressure being high at initial contact. In the post contact phase, as the pressure tube transfers heat to the calandria tube and cools down, thermal expansion of calandria tube and thermal contraction of the pressure tube cause the conductance to rapidly decrease.</p> / Master of Applied Science (MASc)

Organic Photovoltaic Spectral Coverage Improvement

Bamsey, Nathan M. 09 1900 (has links)
<p>p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times; color: #4e4e4e} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times; color: #767676} p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times; color: #636363} span.s1 {color: #636363} span.s2 {color: #878787} span.s3 {color: #767676} span.s4 {color: #393939} span.s5 {color: #252525} span.s6 {color: #4e4e4e} span.s7 {font: 11.5px Times; color: #393939} span.s8 {font: 12.0px Times} span.s9 {font: 12.0px Times; color: #878787} span.s10 {font: 12.0px Times; color: #636363} span.s11 {font: 11.0px Helvetica; color: #4e4e4e} span.s12 {color: #a8a8a8}</p> <p>Methods for improving spectral absorption and efficiency of phthalocyanine based organic photovoltaic devices were investigated. New structures including simple tandem architectures and a novel heteromorphic phthalocyanine (MPc) device were investigated and characterized. The addition of an interlayer of MPc was shown to improve efficiencies of solution based bulk heterojunction devices due to improved open circuit voltage (Voe) and spectral absorption. Solvent treatment has been shown to be an effective method for extending absorpt ion characteristics of trivalent and tetravalent phthalocyanine based solar cells into the near infrared due to polymorphic conversion. Heteromorphic devices incorporating two distinct polymorphs of the same MPc resulted in optimal device characteristics while retaining relative simplicity in fabrication techniques. In this configuration, short circuit current density <strong>(J</strong><strong>sc</strong><strong>) </strong>was enhanced considerably while Voe retained an intermediary voltage between both the</p> <p>control and fully treated devices. Improved spectral response at longer wavelengths had a direct impact on <strong>J</strong><strong>sc </strong>in solvent t reated devices and was a key factor in improved device efficiency. Characterization of new device structures was performed using current-voltage (I-V) measurements, external quantum efficiency (EQE) and a Scanning Electron Microscope (SENI).</p> / Master of Applied Science (MASc)


Behdadi, Azin 12 1900 (has links)
<p>A 2D computational fluid dynamics (CFD) model has been developed to calculate the moderator velocity field and temperature distribution around a single channel inside the moderator of a CANDU reactor after a postulated ballooning deformation of the pressure tube (PT) into contact with the calandria tube (CT). Following contact between the hot PT and the relatively cold CT , there is a spike ill heat flux to the moderator surrounding the CT which may lead to sustained CT dryout. This can detrimentally affect channel integrity if the CT post-dryout temperature becomes sufficiently high to result in thermal creep strain deformation. The present research is focused on establishing the limits for dryout occurrence on the CTs for the situation in which pressure tube-calandria tube contact occurs. In order to consider different flow patterns inside the calandria, both upward awl downward flow directions have been analyzed for buoyancy dominant and momentum dominant flows respectively. The standard k - ε and also k - ω turbulence models associated with logarithmic wall function are applied independently to predict the effects of turbulence and the results have been compared. The governing equations are solved by the finite element software package COMSOL. The buoyancy driven natural convection on the outer surface of a CT has been analyzed to predict the flow and temperature distribution around the single CT considering the local moderator subcooling, wall temperature and heat flux. According to the flow pattern and temperature distribution , it is predicted that stable film boiling generates in the stagnation region on the cylinder and it has been compared with the related experimental data.</p> / Master of Applied Science (MASc)


Hwang, Young Ji 11 1900 (has links)
<p>p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 10.0px Times; color: #343434} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 10.0px Times; color: #4c4c4c} span.s1 {font: 10.5px Times} span.s2 {color: #4c4c4c} span.s3 {color: #343434} span.s4 {color: #7a7a7a} span.s5 {color: #676767} span.s6 {color: #030303}</p> <p>In this project, we have developed an acousto-optic tunable filter (AOTF) -based timeresolved fluorescence spectroscopy (AOTF-TRFS) apparatus capable of acquiring fluorescence spectra and lifetimes of biological fluorescent probes with high data acquisition speed required for real-time clinical diagnostics. The system incorporates a non-collinear TeO₂ AOTF, a gated multichannel plate photomultiplier tube (MCP-PMT), a picosecond Nd:YAG pulsed laser, a digital oscilloscope with high sampling rate and a bifurcated fiber optic probe for light delivery and collection. Typically low throughput of the AOTF was enhanced by collecting both first order diffraction beams. The system performance was evaluated by measuring the fluorescence of 9-CA, fluorescein, NADH and FAD. The emission peaks in time-integrated spectra and the retrieved decay lifetimes were in good agreement with literature values over the desired spectral region between 370 nm and 550 nm. The system was able to collect a set of time-resolved fluorescence decay data for a single point site across a 200 nm wavelength range at 5 run increments within 4 s, which is a significant improvement over the previous generation gratingbased instrument.</p> / Master of Applied Science (MASc)

Accuracy of Boiling Water Reactor Sub channel Void Distribution Predictions

Leung, Kenneth 06 1900 (has links)
<p>The ability to accurately predict the void fraction in a nuclear reactor plays a vital role in the field of nuclear safety. Specifically, high volumetric fractions of vapour in a reactor core can lead to a severe degradation in the ability of the coolant to remove heat from the fuel. Unfortunately, the behaviour of two-phase flow is complex and not particularly well understood, making it infeasible to describe the fluid behaviour in the core analytically. Instead, computer codes which rely heavily on temporal and spatial averaging, as well as empirical correlations, are used to provide a 'best-estimate' of the core thermalhydraulic behaviour. <br /><br />In this study, both the system code RELAP5-3D and the sub channel code ASSERT are used to simulate sub channel void fraction measurements conducted on full scale electrically heated BWR type bundles. RELAP was demonstrated to be capable of predicting the void fraction at the sub channel level to within ±O.l 0 of the reported value 82.6% ofthe time, while ASSERT was successful 95.6% of the time. When the accuracy levels are broken down by sub channel geometry, the comer and side sub channels tended to be the most inaccurately predicted, and this was determined to have been caused by the strong influence of sub channel nnxmg. <br /><br />Uncertainty bands around the simulated points were predicted using the CIAU method developed at the University of Pisa. In the cases simulated with RELAP, the simulated uncertainty bounds enveloped a portion of the experimental uncertainty bounds 95.4% of the time while the ASSERT assessment saw coverage 85.4% of the time.</p> / Master of Applied Science (MASc)

MACPISA-CANDU: Multi-step Approach to Code-coupling for Progression Induced Severe Accidents in CANDU Nuclear Power Plants

Pohl, Daniel J. 09 1900 (has links)
<p>A methodology called the Multi-step Approach to Code-coupling for Progression Induced Severe Accidents in CANDU nuclear power plants (MACPISA-CANDU) was developed and applied. MACPISA-CANDU was used to couple a MATLAB single fuel channel model with a primary heat transport system model developed in MELCOR (MELCOR 1.8.5) to model a small break loss of coolant accident (SBLOCA) in conjunction with a loss of emergency coolant injection (LOECI) in a CANDU 6 nuclear power plant. The specific type of SBLOCA modelled was an individual reactor inlet feeder stagnation break (8.03cm2 ). The early stages of the SBLOCA-LOECI event were the focus of this thesis. 13 seconds after the initiation of the break it was predicted that the pressure tube would heat up to 1473 K and rupture. It is assumed that the calandria tube ruptures along with the pressure tube causing coolant to return to the fuel channel and flow out of the rupture into the calandria vessel. It predicted that the moderator within the calandria vessel would be able to act as an ultimate heat sink and end the transient at 298 seconds. In addition, the MATLAB single fuel channel model· was replaced by a single fuel channel model created in SCDAP/RELAP5 (RELAP/SCDAPSIM Mod 3.4 (bi7)). The coupled SCDAP/RELAP5-MELCOR simulation predicted that the pressure tube would rupture at 23 seconds and subsequently the transient would end at 403 seconds. The results from both code-coupled simulations are shown to be in reasonable agreement with the results of other validated computer models.</p> / Master of Applied Science (MASc)

Experimental and theoretical study of quartz and InP piezoelectric MEMS resonators

Rampal, Abhishaik January 2010 (has links)
<p>MEMS resonators, cantilevers and bridges, using the piezoelectric effect to drive and detect the fundamental resonance mode are studied. Two types of MEMS resonators are investigated in detail: a conventional quartz tuning fork (a two terminal device) and an InP bridge (a three terminal device). While the former is fabricated commercially from an insulating piezoelectric material the latter is fabricated via the controlled growth of a III-V semiconductor material with a non-zero piezoelectric coefficient. To utilize piezoelectricity based on a III-V semiconductor, an In<sub>0.85</sub>Ga<sub>0.15</sub>P /InP heterojunction was fabricated resulting in a depletion width which can be controlled using Schottky contacts. The result of this design is a piezoelectric device, in principle allowing for (dc) tuning of the magnitude of the resonant (ac) deflection and current. The type of deformation of interest is flexural and based on this a general theory relating the bending moment produced due to the piezoelectric stress is presented. Using this bending moment a general expression for the expected deflection and charge is derived analytically. For the quartz case the general expression, which has not been previously derived, is compared to the results of experiments and finite element simulations with good agreement. For the case of InP devices a resonance was not detected. This is attributed to the small piezoelectric coefficient of InP, the stiff bridge design that was chosen and large parasitic effects combining to make it difficult to observe the resonance. The fundamental mechanical noise of the quartz tuning fork was measured and is due to thermal fluctuations at the measurement temperature (~300K) associated with the dissipation in the mechanical system and can be related to the effective resistance of the resonator in the equivalent electrical circuit. Additionally, contributions to the package or dielectric capacitance using two and three terminal setups were studied. The three terminal configuration results in a lower package or dielectric capacitance than for the two terminal configuration.</p> / Master of Applied Science (MASc)

BioMEMS Glucose Sensors

Zdanovich, Andrey 06 1900 (has links)
<p>Since creation of the first glucose sensor for diabetes management in the 1960s, there have been tremendous amount of research devoted to development of sensors suitable for continous in vivo measurement of blood glucose concentration. Such devices would significantly enhance life quality of patients allowing reliable continuous monitoring of their condition and timely administration of medications. Ultimately, it could be combined with an insulin pump to create automatic closed-loop system for tight control of blood glucose level.</p> <p>Analysis of modern glucometers and issues with in vivo measurements suggests the need for a novel approach for glucose sensing. This thesis describes sensors that combine microcantilever transduction paradigm with two Syntactic receptors for glucose, boronic acids and molecular imprinted polymers. These artificial ligands give invaluable advantages of being tunable and very resistant to harsh chemical conditions that would be beneficial for implantable devices. To validate the experiment design and compare results with literature, cantilever sensors with glucose oxidase, an enzyme used in conventional glucometers, were also tested.</p> <p>Cantilever sensors have got a significant attention of the scientific community during last decade. Microcantilevers have an amazing capability to link physical, chemical and biological domains with easily assessable mechanical movements. Such microscopic devices hold a promise of being versatile and very sensitive detectors, which performance scales up with miniaturization. Fabrication process is compatible with GMOS technology opening up an opportunity for low cost mass production.</p> <p>In this work, the developed glucose cantilever sensors are tested in aqueous solution of glucose and their deflections are measured using an optical lever setup.</p> / Master of Applied Science (MASc)

Large LOCA BEAU Analysis of a Generic 900MW CANDU Plant

Sabouri, Pouya 06 1900 (has links)
<p>A RELAP5 input model representative of a 900 MW CANDU plant was created. Due to the one dimensional nature of the code, complex plant components such as heat transport system pumps, fuel channels, and the reactor core were modeled using thermal hydraulically equivalent geometries. The model consists of 301 thermal hydraulic components and heat structures with five boundary conditions specifying the pressure, temperature, and in some cases the mass flow. Spacial convergence of the model was ensured through the implementation of various channel nodalizations (6, 12 and 24 axial nodes) and core representations (single channel group and 6 channel groups per core pass). A control subroutine representative of the pressure control system and steam generator control system was implemented in the model, mimicking the controllers that exist in operational CANDU Reactors. A point kinetics model was used to simulate the reactor power.</p> <p>Uncertainties for parameters related to the modeling of specific phenomenons were obtained from literature sources related to the models in which the parameters belong to. Where sources of open literature were unavailable (error in the void reactivity coefficient, and trip delay times), an estimate was made for the parameter uncertainties. Uncertainties for plant specific parameters were derived from plant operating data obtained either from plant instrument measurements (RIH pressure, RIH temperature, etc) or through code simulation (channel powers, bundle powers, etc). Breaks in the NW reactor inlet header were considered. Due to the additional flow from the pressurizer present in the east loop, it was found that breaks in this loop would lead to slightly lower results. The bulk net energy deposition (NED) related to expected maximum sheath temperatures, and the reactor peak power related to the fuel heat up rate were chosen as the figures of merit. Breaks with a size of 48% of the reactor inlet header area were found to lead to the highest NED. From parametric sensitivity studies performed at the best estimate and non best estimate points for the 48% break, a Phenomena and Key Parameter Identification and Ranking Table (PKPIRT) was established with the void reactivity feed back identified as the highest ranked parameter. It was found that the ranking based on best estimate local studies does not reject parameters that may be of importance at their 95th percentile (non best estimate point).</p> <p>Two best estimate methods along with a conservative approach were implemented. A brute force monte-carlo method consisting of 10,000 simulations provided a probability distribution function for the figures of merits. First and second order GRS methods were found to adequately predict an upper bound for the 95th percentile of the FOMs. Both best estimate methods demonstrated that the consequences of a hypothetical large break LOCA are much more benign than those predicted by the LOE approach.</p> / Master of Applied Science (MASc)

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