Engineering Commons^™

Under-Sampled Reconstruction Techniques For Accelerated Magnetic Resonance Imaging, Mohammad H. Kayvanrad

Electronic Thesis and Dissertation Repository

Due to physical and biological constraints and requirements on the minimum resolution and SNR, the acquisition time is relatively long in magnetic resonance imaging (MRI). Consequently, a limited number of pulse sequences can be run in a clinical MRI session because of constraints on the total acquisition time due to patient comfort and cost considerations. Therefore, it is strongly desired to reduce the acquisition time without compromising the reconstruction quality. This thesis concerns under-sampled reconstruction techniques for acceleration of MRI acquisitions, i.e., parallel imaging and compressed sensing.

While compressed sensing MRI reconstructions are commonly regularized by penalizing the decimated wavelet …

Performance Assessment Of Wireless Two Way Relay Channel Systems, Siramack Ghadimi

Electronic Thesis and Dissertation Repository

The objective of this thesis is theoretical investigations and numerical simulations of Two Way Relay Channel (TWRC) systems, particularly in an impulsive noise environment. Special attention is given to investigation of a TWRC system based on polarized antennas. The first part of the thesis focuses on modelling of impulsive noise and the effect of impulsive noise on TWRC systems. The study was conducted by simulating the wireless TWRC models in the presence of impulsive noise. The bit error probability performance of the channel data was compared and at last their results are shown by graphs. The study has been further …

Internav3d: A Navigation Tool For Robot-Assisted Needle-Based Intervention For The Lung, Srikanth Bhattad

Electronic Thesis and Dissertation Repository

Lung cancer is one of the leading causes of cancer deaths in North America. There are recent advances in cancer treatment techniques that can treat cancerous tumors, but require a real-time imaging modality to provide intraoperative assistive feedback. Ultrasound (US) imaging is one such modality. However, while its application to the lungs has been limited because of the deterioration of US image quality (due to the presence of air in the lungs); recent work has shown that appropriate lung deflation can help to improve the quality sufficiently to enable intraoperative, US-guided robotics-assisted techniques to be used. The work described in …

Magneto-Rheological Actuators For Human-Safe Robots: Modeling, Control, And Implementation, Peyman Yadmellat

Electronic Thesis and Dissertation Repository

In recent years, research on physical human-robot interaction has received considerable attention. Research on this subject has led to the study of new control and actuation mechanisms for robots in order to achieve intrinsic safety. Naturally, intrinsic safety is only achievable in kinematic structures that exhibit low output impedance. Existing solutions for reducing impedance are commonly obtained at the expense of reduced performance, or significant increase in mechanical complexity. Achieving high performance while guaranteeing safety seems to be a challenging goal that necessitates new actuation technologies in future generations of human-safe robots.

In this study, a novel two degrees-of-freedom safe …

On Sensorless Collision Detection And Measurement Of External Forces In Presence Of Modeling Inaccuracies, Vahid Sotoudehnejad

Electronic Thesis and Dissertation Repository

The field of human-robot interaction has garnered significant interest in the last decade. Every form of human-robot coexistence must guarantee the safety of the user. Safety in human-robot interaction is being vigorously studied, in areas such as collision avoidance, soft actuators, light-weight robots, computer vision techniques, soft tissue modeling, collision detection, etc. Despite the safety provisions, unwanted collisions can occur in case of system faults. In such cases, before post-collision strategies are triggered, it is imperative to effectively detect the collisions. Implementation of tactile sensors, vision systems, sonar and Lidar sensors, etc., allows for detection of collisions. However, due to …

Joint Use Of On-Board Reconfigurable Antenna Pattern And Adaptive Coding And Modulation In Satellite Communications At High Frequency Bands, Marco Luccini

Electronic Thesis and Dissertation Repository

The Telecommunication market is driven by the increasing need of the end users for multimedia services which require high data rates. Within the fixed satellite service, frequency bandwidths wide enough to carry such high data rates are to be found in Ka band (26-40 GHz), and Q/V bands (40-50 GHz). However, at Ka band and above, transmitted signals can be severely affected by tropospheric attenuation for substantial percentages of time, resulting in the degradation of the quality and of the availability of communication services. Fade Mitigation Techniques (FMTs) must be used to counteract these severe propagation impairments. In this thesis …

A Hybrid Visual Control Scheme To Assist The Visually Impaired With Guided Reaching Tasks, Duane Jacques

Electronic Thesis and Dissertation Repository

In recent years, numerous researchers have been working towards adapting technology developed for robotic control to use in the creation of high-technology assistive devices for the visually impaired. These types of devices have been proven to help visually impaired people live with a greater degree of confidence and independence. However, most prior work has focused primarily on a single problem from mobile robotics, namely navigation in an unknown environment. In this work we address the issue of the design and performance of an assistive device application to aid the visually-impaired with a guided reaching task. The device follows an eye-in-hand, …

Spectrum Sensing And Multiple Access Schemes For Cognitive Radio Networks, Oscar G. Filio Rodriguez

Electronic Thesis and Dissertation Repository

Increasing demands on the radio spectrum have driven wireless engineers to rethink approaches by which devices should access this natural, and arguably scarce, re- source. Cognitive Radio (CR) has arisen as a new wireless communication paradigm aimed at solving the spectrum underutilization problem. In this thesis, we explore a novel variety of techniques aimed at spectrum sensing which serves as a fundamental mechanism to find unused portions of the electromagnetic spectrum.

We present several spectrum sensing methods based on multiple antennas and evaluate their receiving operating characteristics. We study a cyclostationary feature detection technique by means of multiple cyclic frequencies. …

Modeling And Protection Of Phase Shifting Transformers, Umar Khan

Electronic Thesis and Dissertation Repository

This thesis is mainly focused on the development of (i) phase shifting transformers (PSTs) mathematical and simulation models that can be used for the short-circuit and protection studies, and (ii) new phase shifting transformers protection methods that provide more secure and sensitive solutions than the standard current differential protection.

The first part of this thesis describes and presents the modeling of the single-core standard-delta, and two-core symmetrical and asymmetrical PST for protection and short-circuit studies. The models already available for such types of PSTs have limitations and require detailed test report data from the manufacturers. However, winding test data at …

Resource Allocation In Uplink Long Term Evolution, Aidin Reyhanimasoleh

Electronic Thesis and Dissertation Repository

One of the most crucial goals of future cellular systems is to minimize transmission power while increasing system performance. This master thesis work presents two channel-queue-aware scheduling schemes to allocate channels among active users in uplink LTE. Transmission power, packet delays and data rates are three of the most important criteria critically affecting the resource allocation designs. Therefore, each of these two scheduling algorithms proposes a practical method that assigns resources in such a way so as to optimally maximize data rate and minimize transmission power and packet delays while ensuring the QoS requirements. After converting the resource allocation problem …

Aging And Stabilization Of Pyrolitic Bio-Oils And Model Compounds, A. G. Manjula Taranganie Siriwardhana

Electronic Thesis and Dissertation Repository

When compared to conventional liquid fuels, bio-oil has several undesired properties such as high viscosity, high acidity, high molecular weight, instability, and phase separation upon aging. Therefore, bio-oil needs further stabilization and upgrading before it can be used as a fuel in engines. Phase separation is considered as one of the major issues because it is detrimental to any fuel application and creates problems in storage, transportation and upgrading of bio-oils. This thesis investigates the phase separation of hardwood derived bio-oil under accelerated aging conditions. Different alcohols are used as stabilizing agents and the minimum required amount of alcohol for …

Piezoelectric Transformer And Hall-Effect Based Sensing And Disturbance Monitoring Methodology For High-Voltage Power Supply Lines, Sneha Arun Lele

Electronic Thesis and Dissertation Repository

Advancements in relaying algorithms have led to an accurate and robust protection system widely used in power distribution. However, in low power sections of relaying systems, standard voltage and current measurement techniques are still used. These techniques have disadvantages like higher cost, size, electromagnetic interference, resistive losses and measurement errors and hence provide a number of opportunities for improvement and integration. We present a novel microsystem methodology to sense low-power voltage and current signals and detect disturbances in high-voltage power distribution lines. The system employs dual sensor architecture that consists of a piezoelectric transformer in combination with Hall-effect sensor, used …

A Free Exchange E-Marketplace For Digital Services, Wafa M. I. Ghonaim

Electronic Thesis and Dissertation Repository

The digital era is witnessing a remarkable evolution of digital services. While the prospects are countless, the e-marketplaces of digital services are encountering inherent game-theoretic and computational challenges that restrict the rational choices of bidders. Our work examines the limited bidding scope and the inefficiencies of present exchange e-marketplaces. To meet challenges, a free exchange e-marketplace is proposed that follows the free market economy. The free exchange model includes a new bidding language and a double auction mechanism. The rule-based bidding language enables the flexible expression of preferences and strategic conduct. The bidding message holds the attribute-valuations and bidding rules …

Physical-Layer Security Enhancement In Wireless Communication Systems, Hao Li

Electronic Thesis and Dissertation Repository

Without any doubt, wireless infrastructures and services have fundamental impacts on every aspect of our lives. Despite of their popularities, wireless communications are vulnerable to various attacks due to the open nature of radio propagation. In fact, communication security in wireless networks is becoming more critical than ever. As a solution, conventional cryptographic techniques are deployed on upper layers of network protocols. Along with direct attacks from lower layer, wireless security challenges come with the rapid evolution of sophisticated decipher techniques. Conventional security mechanisms are not necessarily effective against potential attacks from the open wireless environment anymore. As an alternative, …

Reliability Models Applied To Smartphone Applications, Sonia Meskini

Electronic Thesis and Dissertation Repository

Smartphones have become the most used electronic devices. They carry out most of the functionalities of desktops, offering various useful applications that suit the user’s needs. Therefore, instead of the operator, the user has been the main controller of the device and its applications, therefore its reliability has become an emergent requirement. As a first step, based on collected smartphone applications failure data, we investigated and evaluated the efficacy of Software Reliability Growth Models (SRGMs) when applied to these smartphone data in order to check whether they achieve the same accuracy as in the desktop/laptop area. None of the selected …

Single Stage Flyback Micro-Inverter For Solar Energy Systems, Aniruddha Mukherjee

Electronic Thesis and Dissertation Repository

ABSTRACT

Solar energy systems based on photovoltaic (PV) cells have attracted considerable interest in recent years due to their promise of clear and seemingly limitless generated energy. Solar energy systems based on micro-inverter architectures are gaining in popularity as they are less prone to shading and PV cell malfunction since each solar panel in a system has its own low power inverter.

A number of micro-inverters are single stage flyback inverters that are based on the DC-DC flyback topologies. There have been numerous papers on the topic of how to improve the efficiency of dc-dc flyback converters but as far …

Reduced Order Estimation Of Time Varying Wireless Channels In Real Life Scattering Environment, Elena Uchiteleva

Electronic Thesis and Dissertation Repository

This thesis deals with theoretical study and numerical simulation of 2x1 MISO system with Alamouti coding and imperfect channel estimation at the receiver. We adopt two channel models to represent scattering environment. One is Sum of Sinusoids model, which is simple, but does not properly reflect the geometry of scattering environment. The second model uses a set of Modulated Discrete Prolate Spheroidal Sequences to represent the channel in a scenario with scattering from one or more clusters with predefined geometry. The effect of clusters location on estimation quality is examined. Furthermore, we derive reduced complexity Wiener filters for slow flat …

Optimization Of A Boundary Element Approach To Electromagnet Design With Application To A Host Of Current Problems In Magnetic Resonance Imaging, Chad T. Harris

Electronic Thesis and Dissertation Repository

Magnetic resonance imaging (MRI) has proven to be a valuable methodological approach in both basic research and clinical practice. However, significant hardware advances are still needed in order to further improve and extend the applications of the technique. The present dissertation predominantly addresses gradient and shim coil design (sub-systems of the MR system).

A design study to investigate gradient performance over a set of surface geometries ranging in curvature from planar to a full cylinder using the boundary element (BE) method is presented. The results of this study serve as a guide for future planar and pseudo-planar gradient systems for …

Soft-Switching Dc-Dc Converters, Ahmad Mousavi

Electronic Thesis and Dissertation Repository

Power electronics converters are implemented with switching devices that turn on and off while power is being converted from one form to another. They operate with high switching frequencies to reduce the size of the converters' inductors, transformers and capacitors. Such high switching frequency operation, however, increases the amount of power that is lost due to switching losses and thus reduces power converter efficiency.

Switching losses are caused by the overlap of switch voltage and switch current during a switching transition. If, however, either the voltage across or the current flowing through a switch is zero during a switching transition, …

Study Of Stability Analysis Of A Grid-Connected Doubly Fed Induction Generator (Dfig)-Based Small Wind Farm, Baishakhi Dhar

Electronic Thesis and Dissertation Repository

Wind is the most reliable, clean and fast-developing renewable energy source. The DFIG-based variable speed wind turbine system is now the most popular in wind power industry. With power being so in-demanding, a large wind farm needs to be developed to produce more power from a stable system. But before such a large wind farm is installed, better understanding is needed of the system’s intrinsic dynamic behavior, range of stability region and parametric effects on system stability. Hence, a small wind farm with two identical DFIG-based wind turbines connected to a grid network has been considered for this study.

A …

Three-Phase Reduced Switch Topologies For Ac-Dc Front-End And Single-Stage Converters, Dunisha Wijeratne

Electronic Thesis and Dissertation Repository

Conventional three-phase ac-dc converters have two converter stages. They have a front-end converter that converts the input ac voltage into an intermediate dc bus voltage and a second, back-end converter that converts this dc bus voltage into the desired isolated dc output voltage. The front-end converter also performs power factor correction (PFC) and shapes the three-phase input currents so that they are nearly sinusoidal and in phase with the three-phase input voltages. This allows the ac power source to be used in the most efficient manner.

The front-end ac-dc converter is typically implemented with six switches while the back-end dc-dc …

Modeling And Optimization Of Next-Generation Wireless Access Networks, Maysam Mirahmadi

Electronic Thesis and Dissertation Repository

The ultimate goal of the next generation access networks is to provide all network users, whether they are fixed or mobile, indoor or outdoor, with high data rate connectivity, while ensuring a high quality of service. In order to realize this ambitious goal, delay, jitter, error rate and packet loss should be minimized: a goal that can only be achieved through integrating different technologies, including passive optical networks, 4th generation wireless networks, and femtocells, among others.

This thesis focuses on medium access control and physical layers of future networks. In this regard, the first part of this thesis discusses techniques …

Delay Extraction Based Macromodeling With Parallel Processing For Efficient Simulation Of High Speed Distributed Networks, Sourajeet Roy

Electronic Thesis and Dissertation Repository

This thesis attempts to address the computational demands of accurate modeling of high speed distributed networks such as interconnect networks and power distribution networks. In order to do so, two different approaches towards modeling of high speed distributed networks are considered. One approach deals with cases where the physical characteristics of the network are not known and the network is characterized by its frequency domain tabulated data. Such examples include long interconnect networks described by their Y parameter data. For this class of problems, a novel delay extraction based IFFT algorithm has been developed for accurate transient response simulation.

The …

Secure Ofdm System Design For Wireless Communications, Hao Li

Electronic Thesis and Dissertation Repository

Wireless communications is widely employed in modern society and plays an increasingly important role in people's daily life. The broadcast nature of radio propagation, however, causes wireless communications particularly vulnerable to malicious attacks, and leads to critical challenges in securing the wireless transmission. Motivated by the insufficiency of traditional approaches to secure wireless communications, physical layer security that is emerging as a complement to the traditional upper-layer security mechanisms is investigated in this dissertation. Five novel techniques toward the physical layer security of wireless communications are proposed. The first two techniques focus on the security risk assessment in wireless networks …

Design And Evaluation Of Fpga-Based Hybrid Physically Unclonable Functions, Sasan Khoshroo

Electronic Thesis and Dissertation Repository

A Physically Unclonable Function (PUF) is a new and promising approach to provide security for physical systems and to address the problems associated with traditional approaches. One of the most important performance metrics of a PUF is the randomness of its generated response, which is presented via uniqueness, uniformity, and bit-aliasing. In this study, we implement three known PUF schemes on an FPGA platform, namely SR Latch PUF, Basic RO PUF, and Anderson PUF. We then perform a thorough statistical analysis on their performance. In addition, we propose the idea of the Hybrid PUF structure in which two (or more) …

Enhanced Voltage-Sourced Inverters For Large-Scale Grid-Connected Photovoltaic Systems, Hamidreza Ghoddami

Electronic Thesis and Dissertation Repository

This thesis is mainly focused on (i) modeling of large-scale PV systems in order to study the factors that influence the capacity, efficiency, power quality and safety in connection with the power grid and (ii) proposing system- and circuit-level solutions and control strategies/techniques to improve the aforementioned factors. To that end, a model for PV array is developed to study the mismatch power loss in different PV array interconnection methods, especially during the partial shading condition. Further, a two-MPPT structure is proposed to reduce the mismatch power loss in centrally structured PV systems. Then, a single-stage VSC-based system is proposed …

Robotics-Assisted Needle Steering For Percutaneous Interventions: Modeling And Experiments, Ali Asadian

Electronic Thesis and Dissertation Repository

Needle insertion and guidance plays an important role in medical procedures such as brachytherapy and biopsy. Flexible needles have the potential to facilitate precise targeting and avoid collisions during medical interventions while reducing trauma to the patient and post-puncture issues. Nevertheless, error introduced during guidance degrades the effectiveness of the planned therapy or diagnosis. Although steering using flexible bevel-tip needles provides great mobility and dexterity, a major barrier is the complexity of needle-tissue interaction that does not lend itself to intuitive control. To overcome this problem, a robotic system can be employed to perform trajectory planning and tracking by manipulation …

Novel Control Of Pv Solar And Wind Farm Inverters As Statcom For Increasing Connectivity Of Distributed Generators, Mahendra Ac

Electronic Thesis and Dissertation Repository

The integration of distributed generators (DGs) such as wind farms and PV solar farms in distribution networks is getting severely constrained due to problems of steady state voltage rise and temporary overvoltages (TOV). This thesis presents a first time application of a patent-pending PV solar farm control as a dynamic reactive power compensator (STATCOM), termed PV-STATCOM, for mitigating the voltage rise and TOV issues, and significantly enhancing the connectivity of a neighbouring wind farm both during night and day in a realistic distribution feeder in Ontario. The effectiveness of PV-STATCOM is demonstrated even if the solar farm is located 30 …

Electroacoustic And Behavioural Evaluation Of Hearing Aid Digital Signal Processing Features, David J O Suelzle

Electronic Thesis and Dissertation Repository

Modern digital hearing aids provide an array of features to improve the user listening experience. As the features become more advanced and interdependent, it becomes increasingly necessary to develop accurate and cost-effective methods to evaluate their performance. Subjective experiments are an accurate method to determine hearing aid performance but they come with a high monetary and time cost. Four studies that develop and evaluate electroacoustic hearing aid feature evaluation techniques are presented. The first study applies a recent speech quality metric to two bilateral wireless hearing aids with various features enabled in a variety of environmental conditions. The study shows …

Detection, Receivers, And Performance Of Cpfsk And Cpck, Mohammed Zourob

Electronic Thesis and Dissertation Repository

Continuous Phase Modulation (CPM) is a power/bandwidth efficient signaling technique for data transmission. In this thesis, two subclasses of this modulation called Continuous Phase Frequency Shift Keying (CPFSK) and Continuous Phase Chirp Keying (CPCK) are considered and their descriptions and properties are discussed in detail and several illustrations are given. Bayesian Maximum Likelihood Ratio Test (MLRT) is designed for detection of CPFSK and CPCK in AWGN channel. Based on this test, an optimum receiver structure, that minimizes the total probability of error, is obtained. Using high- and low-SNR approximations in the Bayesian test, two receivers, whose performances are analytically …