Theses

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  • Study of single event upsets (SEUS) a survey and analysis
    Study of single event upsets (SEUS) a survey and analysis
    Over the last few years evolution in electronics technology has led to the shrinkage of electronic circuits. While this has led to the emergence of more powerful computing systems it has also caused a dramatic increase in the occurrence of soft errors and a steady climb in failure in time (FIT) rates. This problem is most prevalent in FPGA based systems which are highly susceptible to radiation induced errors. Depending upon the severity of the problem a number of methods exist to counter these effects including Triple Modular Redundancy (TMR), Error Control Coding (ECC), scrubbing systems etc. The following project presents a simulation of an FPGA based system that employs one of the popular error control code techniques called the Hamming Code. A resulting analysis shows that Hamming Code is able to mitigate the effects of single event upsets (SEUs) but suffers due to a number of limitations.
    Study of tip clearance model effects on computational simulation costs for NASA rotor 37.
    Study of tip clearance model effects on computational simulation costs for NASA rotor 37.
    The computational time and resources required to calculate an accurate solution is the key concern in the field of CFD. Especially in the CFD analysis of turbomachines many simulations are required to validate the CFD code and to predict the performance of the turbomachines. In this thesis, the typical computational domain was remodelled and the best computational settings were identified to compute the flows. By modifying the numerical domain, improved grid distribution with less number of nodes was achieved and the results predicted were within the limits specified by NASA for the validation of CFD codes. The modified model with the best computational settings required 28.3% less computational time and 20.5% less computer memory than the typical model and baseline methods.
    Study on airflow and vibraton in a cutting/collection/discharge lawn care system
    Study on airflow and vibraton in a cutting/collection/discharge lawn care system
    Airflows in the cutting/collection/discharge system of a professional lawn care system were studied numerically and experimentally in this thesis. Various three-dimensional and two-dimensional computational fluid dynamics models were developed in order to investigate the complex airflow created by a pair of counter-rotating blades. The three-dimensional models were used to study the actual flows; the two-dimensional models were developed to investigate the optimal shapes of the rotating blades using the mass flow rate per unit power consumption as the objective function. Experiments were carried out mainly to validate the computer models developed in this study for airflow velocity and power usage for an actual cutting system. Vibrations of a cutting blade were studied using the finite element method and experiments. It was found that the blades will experience resonance under normal operating conditions.
    Study on airflow and vibraton in a cutting/collection/discharge lawn care system
    Study on airflow and vibraton in a cutting/collection/discharge lawn care system
    Airflows in the cutting/collection/discharge system of a professional lawn care system were studied numerically and experimentally in this thesis. Various three-dimensional and two-dimensional computational fluid dynamics models were developed in order to investigate the complex airflow created by a pair of counter-rotating blades. The three-dimensional models were used to study the actual flows; the two-dimensional models were developed to investigate the optimal shapes of the rotating blades using the mass flow rate per unit power consumption as the objective function. Experiments were carried out mainly to validate the computer models developed in this study for airflow velocity and power usage for an actual cutting system.Airflows in the cutting/collection/discharge system of a professional lawn care system were studied numerically and experimentally in this thesis. Various three-dimensional and two-dimensional computational fluid dynamics models were developed in order to investigate the complex airflow created by a pair of counter-rotating blades. The three-dimensional models were used to study the actual flows; the two-dimensional models were developed to investigate the optimal shapes of the rotating blades using the mass flow rate per unit power consumption as the objective function. Experiments were carried out mainly to validate the computer models developed in this study for airflow velocity and power usage for an actual cutting system.Vibrations of a cutting blade were studied using the finite element method and experiments. It was found that the blades will experience resonance under normal operating conditions.
    Subcarrier availability in OFDM systems with imperfect carrier synchronization in deep fading noisy doppler channels
    Subcarrier availability in OFDM systems with imperfect carrier synchronization in deep fading noisy doppler channels
    In this thesis, we investigate the performance of a multi-user OFDM system under imperfect synchronization which is caused due to noise, Doppler shift and frequency selective fades in the channel. Analytical result indicates that the SNR degrades as the average power of the channel impairments such as AWGN, carrier frequency offset due to Doppler frequency and fading gain is increased.The SNR degradation leads to imperfect synchronization and hence decreases the total number of subcarriers available for allocation. Based on Monte Carlo analysis, 22% loss in the number of allocatable subcarriers is noticed under imperfect synchronization as compared to perfect synchronization. We utilize empirical modelling to characterize the available number of subcarriers as a Poisson random variable. In addition, we determine the percentage decrease in the total number of allocatable subcarriers under varying channel parameters such as AWGN, Doppler frequency and fading gain. The results indicate 19% decrease in the number of available subcarriers as average AWGN power is increased by 10dB; 44% decrease as the Doppler frequency is varied between 10Hz to 100Hz; and 56% decrease as the fading gain is varied between 0dB to -30dB. Furthermore, the evaluation of an adaptive subcarrier allocation algorithm under imperfect synchronization. Hence, radio resource allocation for multicarrier systems should consider the percentage loss in the available subcarriers under imperfcet synchronization.
    Subject matter identification by means of community outreach
    Subject matter identification by means of community outreach
    The purpose of this practical thesis project was to create a guidebook for collecting subject-based information gathered through community participation and collaboration. Specifically, this involved collecting subject descriptions for a photograph collection based on an organized and planned meeting with local residents familiar with the contents of the images. All fieldwork was completed over a nine-week period, from June 5 through August 2, 2006, at the Bruce County Museum and Cultural Centre, Southampton, Ontario with the John H. Scougall Collection. 105 images were selected for discussion and subject identification by community members. What follows is a guidebook to inform others how to carry out such a project. Each section begins with general comments and ideas, followed by specific examples of what took place with the Scougall Collection and the participating residents of Kincardine.
    Submicron and nano surface patterning using nanosecond laser technique
    Submicron and nano surface patterning using nanosecond laser technique
    Direct writing by laser techniques in the micro and nanostructuring scale is very important for the fabrication of new materials and multifunctional devices. They have proven to be very successful tools for precision machining and microfabrication with applications in optical devices, microelectronics, medical device, biomedical, defense applications, and MEMS. Focused nanosecond (ns) laser pulses can produce periodic structures and arrays pattern structures in semiconductors and thin metallic film on shaped surfaces. The achievable structure size is restricted by the wavelength and diffraction limit as well as it is determined by material properties and laser pulse stability. This thesis proposes a nanosecond laser nanostructuring technique in common optical path configuration to examine the limitations of the currently used fabrication methods and type of setups used; the competitive edge is using nanosecond lasers as a tool. Prospectively, this technology can be applied for femtosecond laser fabrication, because this is an easy, simple and common optical path configuration. For this experimental setup, the use of a common optical path configuration for automatic interference offers equals path lengths. It is not required for complicated optical setups while in femtosecond laser setups, it is extremely important to use path compensation in order to offer time delay for one laser beam due to a long path and more optical components. A low repetition rate, low power nanosecond laser system is investigated to preventing the (HAZ) conditions. The influence of the laser repetition rate and pulse energy on the size and quality of submicron features which fabricated on silicon wafers and thin gold film is investigated. In terms of nanomachining below the ablation threshold (surface patterning), the influence of laser fluence, repetition rate and pulse energy on the spacing as well as diameter of dots created on silicon wafer surface is examined. These studies show the capability of the proposed system of nanosecond laser in common optical path configuration in meeting the industry requirements.
    Suboptimal rate adaptive resource allocation in multiuser OFDM communication systems
    Suboptimal rate adaptive resource allocation in multiuser OFDM communication systems
    This thesis aims to study the performance of adaptive resource allocation in the downlink of multiuse OFDM systems with fixed or varialbe rate requirements (with fairness consideration) as well as low complexity algorithms for real-time implementations in practical systems.We first verify the simplifying assumption of flat transmit power over the entire bandwidth. Two different optimal and suboptimal power allocation schemes are applied in a single-user system and the decrease in the total throughput due to the presence of the power mask on subcarriers is measured. Based on the comparison of the achieved data rates, a flat transmit power is then assumed in the proposed suboptimal multiuser resource allocation algorithms. Two suboptimal resource allocation algorithms are then proposed using this simplifying assumption. The objective of the first algorithm is to maximize the total throughput while maintaining rate proportionality among the users. The proposed suboptimal algorithm prioritizes the user with the highest sensitivity to the subcarrier allocation and the variance over the subchannel gains is sued to define the sensitivity of each user. The second algorithm concerns rate adaptive resource allocation in multiuser OFDM systems with fixed rate constraints for each user. We propose a suboptimal joint subchannel and power allocation algorithm which attempts to maximize the total throughput wihile supporting the users with their minimum rate requirments. The main feature of this algorithm is its low complexity while achieving close to optimum capacity.
    Subregional activation of the amygdala during emotional memory encoding in posttraumatic stress disorder: an FMRI investigation
    Subregional activation of the amygdala during emotional memory encoding in posttraumatic stress disorder: an FMRI investigation
    Posttraumatic stress disorder (PTSD) is characterized as a debilitating and disruptive psychiatric condition that arises following exposure to a single or multiple traumatic events. The disorder expresses itself as a constellation of physical, cognitive, and emotional symptoms and leads to significant impairment in social and occupation functioning. In Canada, the majority of Canadians are exposed to at least one traumatic event in their lifetime and almost one in ten Canadians go on to develop the disorder. Despite evolving conceptualizations of PTSD, re-experiencing symptoms related to recurrent and intrusive memories remains a core feature of the disorder, and these recollections often accompany other changes in memory. The mechanisms underlying memory disturbances in PTSD however, remain less clear. Early fear conditioning studies in non-human primates implicated alterations to the basolateral subdivision of the amygdala (BLA) in the pathogenesis of PTSD, due to its role in learning and memory for threatening events. The overall goal of this dissertation was to examine whether PTSD is associated with alterations in functional brain activation across three distinct subregions of the amygdala during memory encoding of emotional events varying in valence and arousal. Specifically, using functional magnetic resonance imaging (fMRI) and analysis methods based on probabilistic cytoarchitectonic mapping, activation of the amygdala subregions was examined for a series of photos that participants viewed in the fMRI scanner, and then later remembered during a recognition memory test. Consistent with the study’s primary hypothesis, results those with PTSD (n = 11) showed greater activation of the BLA during encoding of negative relative to positive photos. This effect was unique to the BLA compared with the centromedial amygdala. No subregional differences emerged in the trauma-exposed control group (n = 11). Moreover, the BLA memory effect in the PTSD group was also observed when comorbid depressive symptoms were statistically controlled, and showed a marginally significant effect toward independently predicting symptom severity. Contrary to the study’s hypotheses, there was no evidence of altered BLA activity during memory encoding of high arousing relative to low arousing events. Overall, the results of this dissertation suggest that task-based activation of the amygdala in PTSD is not consistent across the entire structure, and that memory-related processing of negative information is associated with recruitment of the BLA.
    Subspace predictive control: stability and performance enhancement
    Subspace predictive control: stability and performance enhancement
    In the absence of prior knowledge of a system, control design relies heavily on the system identifi- cation procedure. In real applications, there is an increasing demand to combine the usually time consuming system identification and modeling step with the control design procedure. Motivated by this demand, data-driven control approaches attempt to use the input-output data to design the controller directly. Subspace Predictive Control (SPC) is one popular example of these algorithms that combines Model Predictive Control (MPC) and Subspace Identification Methods (SIM). SPC instability and performance deterioration in closed-loop implementations are majorly caused by either poor tuning of SPC horizons or changes in the dynamics of the system. Stability and performance analysis of the SPC are the focus of this dissertation. We first provide the necessary and sufficient condition for SPC closed-loop stability. The results introduce SPC stability graphs that can provide the feasible prediction horizon range. Consequently, these stability constraints are included in SPC cost function optimization to provide a new method for determining the SPC horizons. The novel SPC horizon selection enhances the closed-loop performance effectively. Note that time-delay estimation and order selection in system modeling have been a challenging step in applications and industry. Here, we propose a new approach denoted by RE-based TDE that simultaneously and fficiently estimates the time-delay for the SIM framework. In addition, we use the recently developed MSEE approach for estimating the system order. Moreover, we propose an arti- ficial intelligence approach denoted by Particle Swarm Optimization Based Fuzzy Gain-Scheduled SPC (PSO-based FGS-SPC). The method overcomes the issue of on-line adaptation of SPC gains for systems with variable dynamics in the presence of the noisy data. The approach eliminates existing tuning problem of controller gain ranges in FGS and updates the SPC gains with no need to apply any external persistently excitation signals. As a result, PSO-based FGS-SPC provides a time efficient control strategy with fast and robust tracking performance compared to conventional and state of the art methods.
    Substrate Dependent Regulation of the Human Equilibrative Nucleoside Transporter 1 (hENT1) in HEK293 Cells
    Substrate Dependent Regulation of the Human Equilibrative Nucleoside Transporter 1 (hENT1) in HEK293 Cells
    Nucleosides and nucleoside analog drugs enter cells through nucleoside transporters, such as the human equilibrative nucleoside transporter 1 (hENT1). The regulation of nucleoside transporters is poorly understood. In this study, through fluorescence-activated cell sorting (FACS) analyses, confocal microscopy and radio-ligand binding assays, I show a decrease in hENT1 abundance at the plasma membrane (PM) in HEK cells treated in the presence of a bolus amount of cytidine (40μM) for 6 hours. Kinetic and transport assays indicate that the remaining hENT1 population at the PM has a higher Vmax and Km but there is no change in overall substrate uptake compared to untreated cells. I also show that cytidine pre-treatment leads to an increased cytotoxicity from gemcitabine (a nucleoside analog drug). These are the first data that show direct substrate dependent regulation of a nucleoside transporter by a mechanism that may involve increased recycling/internalization of the transporter.