Theses

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  • Three-dimensional GIS-based approach for highway design consistency evaluation
    Three-dimensional GIS-based approach for highway design consistency evaluation
    The mission of transportation is to transport people and goods safely and efficiently. Therefore, traffic safety has been one of the most important topics since the birth of the subject of transportation. Improving highway design consistency is considered as an important strategy for improving traffic safety. Geographic information systems (GIS) has been popular for decades due to its great ability to deal with spatial or spatially-related data. Contributions from GIS to transportation have become well known in some aspects. However, GIS, especially its 3D visualization function, has not, in previous studies, been integrated into the core of the highway design consistency evaluation procedure. In contrast, the major objective of this thesis research is to integrate the latest advanced GIS techniques including its 3D visualization function and the state-of-the-art knowledge from previous studies into the highway design consistency evaluation procedure. By adding new functions specifically developed for highway design consistency evaluation, a 3D GIS-based highway design consistency evaluation methodology is developed. This newly developed methodology and associated software tools, as a combination of GIS, including its 3D visualization function, and highway consistency modules, will make significant contributions in the following aspects: highly automated consistency evaluation procedure, 3D-alignment-based consistency level analysis, impressive evaluation result presentation, and spatially based consistency improvement suggestion. Verification of this methodology on a typical 3D-highway segment in Ontario shows very promising results. This study, to a great extent, is convincing that, in the near future, designers could be able to design highways in a regular GIS environment.
    Three-dimensional filters for multiview stereoscopic applications using layered depth images
    Three-dimensional filters for multiview stereoscopic applications using layered depth images
    This thesis proposes an extension of two-dimensional (2D) spatial filtering into three-dimensions for multiview stereoscopic applications using the layered depth image (LDI) representation. The proposed filtering scheme takes advantage of the depth information available when an image is represented with layers, and can return results that are comparable to or better than 2D filtering techniques for smoothing or sharpening stereoscopic images. In addition, the proposed filtering scheme is more efficient for multiview stereoscopic applications using LDIs than conventional 2D filtering since the filter needs to be applied only once for n views, whereas 2D filtering requires each view to be filtered separately (increasing computation time).The proposed filtering method for smoothing stereoscopic images was also subjectively evaluated in a study involving 15 people. The results from this study indicated that the proposed filtering scheme received similar scores for both viewer comfort and naturalness when compared to the 2D bilateral filter.
    Three-dimensional modeling of Ge₁₋xSix by the traveling solvent method to study the effect of gravity orientations under different rotational speed
    Three-dimensional modeling of Ge₁₋xSix by the traveling solvent method to study the effect of gravity orientations under different rotational speed
    This thesis presents a 3-D numerical simulation study for the growth of germanium-silicon (Ge₁₋xSix) under different gravity orientation and axial rotation. The process use for crystal growth of Ge₁₋xSix is traveling solvent method known as TSM. The TSM process has been tested on many alloys producing uniform and uncontaminated crystal products. In this model a mesh sensitivity analysis his been carried out to find an optimum mesh which provides accurate results while saving computational time. The full Navier-Stokes equations together with the energy, mass transport and continuity equations were solved numerically using the finite element technique. The application of gravity orientation and crucible rotation to the traveling solvent method is an attempt to control the buoyancy induced convection throughout the melt and to suppress the three-dimensional characteristics of unsteady heat flow. These different speeds of rotation were shown to have a considerable effect on the buoyancy induced flow. The solute distribution throughout the melt was also affected substantially. Taking these two factors into account plays a crucial role in the crystal growth process. The speed of rotation showed to have a significant effect on the intensity of the convective flow in the melt and an optimal rotational speed was encountered.
    Three-dimensional modeling of SiGe by the traveling solvent method in the presence of magnetic field and rotating crucible
    Three-dimensional modeling of SiGe by the traveling solvent method in the presence of magnetic field and rotating crucible
    A three-dimensional numerical simulation study was carried out for crystal growth of SiGe by the traveling solvent method (TSM). The effects of magnetic field intensity and sample rotation on the transport structures (fluid flow, heat and mass transfer and concentration) in the solvent were investigated in detail. The full steady-state Navier-Stokes equations, as well as the energy, mass transport and continuity equations were solved numerically using the finite element method. An external axial magnetic field is applied to suppress convection in the solvent. It was found that the intensity of the flow at the centre of the crucible decreases at a faster rate compared to the flow near the walls when increasing the magnetic field intensity. This behaviour creates a stable and uniform silicon distribution in the horizontal plane near the growth interface. The application of crucible rotation in the presence of the axial magnetic field is an attempt to control the buoyancy induced convention throughtout the solvent region. It was observed that, in the application of rotation, there is no significant change to suppress the flow intensity. It was found that the rotating magnetic field (RMF) has a marked effect on the silicon concentration, changing it from convex to nearly flat when the magnetic field intensity increases. An alternative method for removing buoyancy convection from the melt is growing the crystal in a gravity free environment. The microgravity (104ˉg) is numerically simulated and compared with the ground base condition.
    Three-dimensional modelling of ground surfaces
    Three-dimensional modelling of ground surfaces
    The efficiency and quality of abrasive machining processes influence costs and quality of elements produced, as well as whole products. Hence, the estimation of surface characteristics can greatly facilitate the requirements of performance evaluation. But the surface finish is dominated by many factors and physical model which could predict it is not practical. Therefore, it is very important to develop modelling techniques for the reliable prediction of surface characteristics.This thesis describes the development of a three-dimensional predictive modellling methodology for surface characteristics of a ground surface. The methodology uses solid modelers to generate the chips and remove them from the solid model of the workpiece. This results in surface model which represents the groud surface in three dimensions. Various surface characteristics can then be deducted from this model.The modelling of individual abrasive grains follows a statistical distribution which depends on the grinding tool characteristics. The cutting path depends on the relative motion between the tool and workpiece.The methodology was implemented for three different types of tool path. The results are in agreement with expected values.
    Three-dimensional numerical simulation of crystal growth using TSM under g-jitter conditions
    Three-dimensional numerical simulation of crystal growth using TSM under g-jitter conditions
    The goal of this thesis is to study the effect of residual gravity on crystal growth of Silicon Germanium GE0.98 Si0.02 using the Traveling Heater Method (THM). This method has proven to be one of the most efficient techniques to grow high-quality crystals because it can be grown at relatively low temperatures compared to existing crystal growth techniques. Yet, because of natural convection due to earth's gravity, imperfection in terms of silicon distribution along the growth interface occurs. By growing crystals in a space environment, residual gravity represented by a static microgravity component and a sinusoidal component would decrease the intensity of the convective flow, which in return would lead to a more uniform silicon distribution. However, g-jitter fluctuation has proven to have a noticeable effect on the silicon distribution. Therefore, as an initial step to understand the behavior of crystal growth in space, each component of the g-jitter force will be studied thoroughly. The momentum, mass and energy equations, representing the 3D TSM model, were solved using finite element means. The preliminary results indicate that the complexity and the intensity of the silicon distribution along the growth interface are proportional to the convective flow, that partially controls the migration of silicon. Therefore, the quality of the crystal growth is assessed based on the behavior of the flow along the solvent regime. Based on the imposed static gravity in the range of 10-6 go to 10-3 go, the flow was determined to be in a diffusion mode with a velocity ranging from 10-6 cm/sec to 10-3 cm/sec. As a matter of fact, the flow intensity was noted to be positively proportional to the dominant component of both the static and the amplitude of the imposed g-jitter and negatively proportional to the frequency of the sinusoidal g-jitter. Consequently, realistic space growth conditions have proven to be an effective way of producing a homogeneous crystal since a flawless crystal silicon distribution is obtained at the growth interface.
    Through the Lens of Fashion: an Analysis of the Clothing Styles of Women In Early Victorian Ontario
    Through the Lens of Fashion: an Analysis of the Clothing Styles of Women In Early Victorian Ontario
    The stories of the women who lived in and contributed to the growth of early Victorian Canada have been largely untold. Often named only as an adjunct to male heads of households, women have been nearly invisible in the history of this nation. This research project is a study of the women and their dress from 1840 to 1860 as seen through daguerreotypes. It verifies that sitters showed a high level of consistency in their choice of style, fabric, and accessories, but exhibited individuality and personality within the confines of popular fashion. Using information gleaned from the photographs, this examination identifies signs and symbols that were part of the philosophy of early Victorian Canada. As a scholarly document, it provides a series of images that can be used to establish the timelines of Canadian dress and a firm base upon which to build a greater knowledge of Canadian fashion.
    Through the cracks: An examination of women, homelessness and health care.
    Through the cracks: An examination of women, homelessness and health care.
    This study provides a unique perspective on health care and emergency shelter services for older women dealing with homelessness as well as complex health care needs in the city of Toronto. Qualitative interviews with frontline shelter staff highlight the assumption that older women who are discharged from hospital will be cared for in an institutional setting such as an emergency shelter. Discussion focuses on how this assumption fails to adequately meet the needs of older women and how lack of adequate housing has a negative impact on their access to healthcare.
    Throughput Analysis of Opportunistic Channel Access Techniques in Cognitive Radio Systems
    Throughput Analysis of Opportunistic Channel Access Techniques in Cognitive Radio Systems
    In recent studies it was found out that previously allocated frequency spectrum is not fully utilized in all the wireless systems. Cognitive radio is the new concept to access this underutilized spectrum and, also a promising technology to cope with the ever increasing bandwidth demand for next generation wireless networks. Cognitive radio network can be classified into three different categories: interweave, underlay and overlay. In an interweave cognitive radio system, the unoccupied spectrum holes can be shared by cognitive users with minimal collision with primary users (spectrum owners) whereas in an underlay system, concurrent transmission is allowed with an interference threshold to the primary users. In an underlay system, cognitive users generally transmit at very low power. In an overlay system, cognitive users, similar to underlay cognitive radio systems, concurrently transmit with primary users but cognitive users may know the codewords of the primary transmitter. Hence, using that knowledge, cognitive transmitter may adopt different coding techniques to cancel/mitigate the interference at the primary receiver and/or it may assist the primary system by relaying primary user’s data. In this thesis, we improve the throughput/bit error rate performance of a cognitive radio system by effectively accessing the channels. Throughout the thesis we assume that cognitive user can sense only one channel at a time and we analyze the performance with perfect and imperfect sensing.First, we propose a novel opportunistic access scheme for cognitive radios in an interweave cognitive system, that considers the channel gain as well as the predicted idle channel probability (primary user occupancy: busy/idle). In contrast to previous work where a cognitive user vacates a channel only when that channel becomes busy, the proposed scheme requires the cognitive user to switch to the channel with the next highest idle probability if the current channel’s gain is below a certain threshold. We derive the threshold values that maximize the long term throughput for various primary user transition probabilities and cognitive user’s relative movement (Doppler spread). Then, we propose a three state Markov model to analyze the performance of a hybrid interweave-underlay system where the primary user’s occupancy states are hidden, but their activity statistics, ranges of transmission, and interference thresholds are known. The primary user is assumed to be in one of the three transmission modes as seen by the cognitive user: busy, concurrent and idle. We derive the transmission mode selection criteria (interweave/underlay) to improve the long term throughput of a cognitive user based on the primary user traffic characteristics and the achievable throughput ratio between the two modes of operation. Later, we incorporate the sensing error in our analysis where we study the optimal access strategy. Since the optimal policy requires the channel to be sensed in each time-slot, we propose and analyze a forward algorithm based cross-layer frame based sensing policy.Finally, we focus on the overlay cognitive radio system where cognitive relay nodes assist the primary transmission. As an initial study, we select a two-hop decode-and-forward orthogonal frequency and code division multiplexing based relay network. For this system, we propose adaptive channel allocation and, power allocation strategies and the bit error rate performance is numerically evaluated. This preliminary analysis can be extended to overlay cognitive systems.
    Timber Framing Factor in Toronto Residential House Construction
    Timber Framing Factor in Toronto Residential House Construction
    Achieving energy efficiency with thermal control in residential houses is crucial for the reduction in the energy consumption. Timber framing as the main structural component in the building envelope has a big influence on the effective R-value depending on the framing percentage, and this impacts the overall thermal performance of the building. This project, carried out in Canada, measured the typical framing percentages that are achieved in residential construction sites and compares them with code recommendations. It provides framing factors measured for 17 residential units under construction including detached, row-housing, and semi-detach dwelling units in three different locations in the Toronto area. Detailed on site measurements provide data for numerical calculation to evaluate the amount of framing within external walls, ceilings, and exposed floors. The overall framing factor calculated for each dwelling is found to exceed the recommended percentage by Canadian Model National Energy code for dwellings and ASHRAE Handbook- Fundamental. The research considers the impact that additional regular thermal bridging from the increased framing percentage will have on the effective R-value, and consequently, the impact on thermal effectiveness of the envelope leading to an increase in the overall energy above the expectations of the codes and standards.
    Time-Frequency Feature Analysis
    Time-Frequency Feature Analysis
    Most of the real-world signals in nature are non-stationary, i.e., their statistics are time variant. Extracting the time-varying frequency characteristics of a signal is very important in understanding the signal better, which could be of immense use in various applications such as pattern recognition and automated-decision making systems. In order to extract meaningful time-frequency (TF) features, a joint TF analysis is required. The proposed work is an attempt to develop a generalized TF analysis methodology that exploits the benefits of TF distribution (TFD) in pattern classification systems as related to discriminant feature detection and classification. Our objective is to introduce a unique and efficient way of performing non-stationary signal analysis using adaptive and discriminant TF techniques. To fulfill this objective, in the first point, we build a novel TF matrix (TFM) decomposition that increases the effectiveness of segmentation in real-world signals. Instantaneous and unique features are extracted from each segment such that they successfully represent joint TF structure of the signal.In the second point, based on the above technique, two unique and novel discriminant TF analysis methods are proposed to perform an improved and discriminant feature selection of any non-stationary signals. The first approach is a new machine learning method that identifies the clusters of the discriminant features to compute the presence of the discriminative pattern in any given signal, and classify them accordingly. The second approach is a discriminant TFM (DTFM) framework, which is a combination of TFM decomposition and the discriminant clustering techniques. The developed DTFM analysis automatically identifies the differences between different classes as the distinguishing structure, and uses the identified structure to accurately classify and locate the discriminant structure in the signal. The theoretical properties of the proposed approaches pertaining to pattern recognition and detection are examined in this dissertation. The extracted TF features provide strong and successful characterization and classification of real and synthetic non-stationary signals. The proposed TF techniques facilitate the adaptation of TF quantification to any feature detection technique in automating the identification process of discriminatory TF features, and can find applications in many different fields including biomedical and multimedia signal processing.
    Time-Frequency Signal Synthesis and Its Application in Multimedia Watermark Detection
    Time-Frequency Signal Synthesis and Its Application in Multimedia Watermark Detection
    A novel approach is proposed in this thesis to synthesize the time domain chirp signal from the joint time-frequency distribution (TFD). The objective is to reconstruct the original signal from its corrupted version. The new signal synthesis technique is based on the Discrete Polynomial Phase Transform (DPPT) and the TFD of the signal to be synthesized. The TFD is used to separate the mono-component signals from a multi-component signal. The DPPT is then applied on the estimated mono-components to have a final synthesized version of the individual time domain signals. The candidate TFD to be used in the synthesis technique is chosen from a group of common TFDs based on their performance with different types of signals. The criteria for the comparison are joint time-frequency localization, low susceptibility to noise, cross-term suppression and the precision of the instantaneous frequency estimated from these distributions. Smoothed Psuedo Wigner-Ville Distribution is chosen as the processing TDFD in the proposed signal synthesis technique. The proposed chirp synthesis technique is applied to detect the presence of the chirp signal embedded as a watermark message in multimedia security applications. The technique can detect the presence of chirp signals from a corrupted chirp with a bit error rate up to signal synthesis is proved to be less than that of the detection method based on the Hough Radon Transform and the proposed signal synthesis technique may also be used as an error correction tool in other applications.