Engineering Commons^™

Analysis, Segmentation And Prediction Of Knee Cartilage Using Statistical Shape Models, Joseph Michael Johnson

Doctoral Dissertations

Osteoarthritis (OA) of the knee is one of the leading causes of chronic disability (along with the hip). Due to rising healthcare costs associated with OA, it is important to fully understand the disease and how it progresses in the knee. One symptom of knee OA is the degeneration of cartilage in the articulating knee. The cartilage pad plays a major role in painting the biomechanical picture of the knee. This work attempts to quantify the cartilage thickness of healthy male and female knees using statistical shape models (SSMs) for a deep knee bend activity. Additionally, novel cartilage segmentation from …

Reconstruction Of Patient-Specific Bone Models From X-Ray Radiography, Hatem Amin Abdel Fattah El Dakhakhni

Doctoral Dissertations

The availability of a patient‐specific bone model has become an increasingly invaluable addition to orthopedic case evaluation and planning [1]. Utilized within a wide range of specialized visualization and analysis tools, such models provide unprecedented wealth of bone shape information previously unattainable using traditional radiographic imaging [2]. In this work, a novel bone reconstruction method from two or more x‐ray images is described. This method is superior to previous attempts in terms of accuracy and repeatability. The new technique accurately models the radiological scene in a way that eliminates the need for expensive multi‐planar radiographic imaging systems. It is also …

Development Of Si Device Based Power Converters For High Temperature Operation In Hev Applications, Zhuxian Xu

Doctoral Dissertations

In this dissertation, the feasibility of operating Si devices at 200 ˚C [degree Celsius] is investigated and the guidelines on the development of a high temperature Si converter for operating with 105 ˚C high temperature liquid coolant in hybrid electrical vehicle (HEV) applications are provided.

First, the characterization of a Si IGBT operating at 200 ˚C junction temperatures is presented. It is shown that the commercial 175 ˚C Si IGBT under test can be successfully switched at an elevated junction temperature of 200 ˚C with increased but acceptable losses.

Second, a comprehensive evaluation of Si IGBT ruggedness at high temperature …

Decoding The `Nature Encoded' Messages For Wireless Networked Control Systems, Shuping Gong

Doctoral Dissertations

Because of low installation and reconfiguration cost wireless communication has been widely applied in networked control system (NCS). NCS is a control system which uses multi-purpose shared network as communication medium to connect spatially distributed components of control system including sensors, actuator, and controller. The integration of wireless communication in NCS is challenging due to channel unreliability such as fading, shadowing, interference, mobility and receiver thermal noise leading to packet corruption, packet dropout and packet transmission delay. In this dissertation, the study is focused on the design of wireless receiver in order to exploit the redundancy in the system state, …

Bayesian Dictionary Learning For Single And Coupled Feature Spaces, Li He

Doctoral Dissertations

Over-complete bases offer the flexibility to represent much wider range of signals with more elementary basis atoms than signal dimension. The use of over-complete dictionaries for sparse representation has been a new trend recently and has increasingly become recognized as providing high performance for applications such as denoise, image super-resolution, inpaiting, compression, blind source separation and linear unmixing. This dissertation studies the dictionary learning for single or coupled feature spaces and its application in image restoration tasks. A Bayesian strategy using a beta process prior is applied to solve both problems.

Firstly, we illustrate how to generalize the existing beta …

Wide-Area Measurement And Applications In Power System Dynamic Modeling And Control, Yong Liu

Doctoral Dissertations

Synchrophasor has been becoming the foundational element of power grid wide-area measurement system (WAMS) since first developed in 1980s. By utilizing global positioning system (GPS) time synchronization technique, synchrophasors offer highly accurate time-synchronized phasor measurements that can provide system operators with real-time information of operation status.

Frequency disturbance recorders (FDRs) are installed on the distribution level to measure power system dynamics and considered as a type of single-phase synchrophasors. In this dissertation, a detailed procedure for the FDRs’ calibration is summarized and a preliminary test of their dynamic performance is carried out. Moreover, this dissertation investigates the impact of GPS …

All-Sic Three-Phase Converters For High Efficiency Applications, Fan Xu

Doctoral Dissertations

The dissertation aims to improve the efficiency of three-phase converters using SiC power devices.The methodology to design a high efficiency all-SiC three-phase converter is presented. Four aspects are included: SiC power device evaluation, power loop parasitics analysis, high efficiency current source rectifier, and paralleled current source rectifier system.

The SiC JFET and MOSFET are tested based on voltage source and current source structures respectively. The dissertation proposes a device switching test circuit based on current source topology to simulate current commutation processes. The circuit can evaluate the switching performance and calculate switching loss of a power device used in a …

An Integrated Plasma Spectroscopic And Capacitive Sensing Platform For Water Quality Diagnostics, John William Sweeney

Doctoral Dissertations

Even in modern times, the consumption of polluted water continues to inflict tremendous suffering on millions of people worldwide that is largely preventable with adequate sanitation practices, routine water quality diagnostics, and treatment. However, conventional water quality monitoring practices remain a time consuming endeavor, where water samples collected on-site are transported to off-site laboratories for evaluation with laboratory-scale chemical analysis devices. While considerable efforts have been made to miniaturize these devices for in-field use, many of the devices reported in the literature provide an incomplete assessment of a water contaminant's environmental impact by focusing on identifying its chemical composition and …

Design Of Wireless Communication Networks For Cyber-Physical Systems With Application To Smart Grid, Rukun Mao

Doctoral Dissertations

Cyber-Physical Systems (CPS) are the next generation of engineered systems in which computing, communication, and control technologies are tightly integrated. On one hand, CPS are generally large with components spatially distributed in physical world that has lots of dynamics; on the other hand, CPS are connected, and must be robust and responsive. Smart electric grid, smart transportation system are examples of emerging CPS that have significant and far-reaching impact on our daily life.

In this dissertation, we design wireless communication system for CPS. To make CPS robust and responsive, it is critical to have a communication subsystem that is reliable, …

Control Studies Of Dfig Based Wind Power Systems, Zhiqiang Jin

Doctoral Dissertations

Wind energy as an outstanding and competitive form of renewable energy, has been growing fast worldwide in recent years because of its importance to reduce the pollutant emission generated by conventional thermal power plants and the rising prices and the unstable supplies of fossil-fuel. However, in the development of wind energy, there are still many ongoing challenges.

An important challenge is the need of voltage control to maintain the terminal voltage of a wind plant to make it a PV bus like conventional generators with excitation control. In the literature with PI controllers used, the parameters of PI controllers need …

Optimal Distribution Reconfiguration And Demand Management Within Practical Operational Constraints, Benyamin Moradzadeh

Doctoral Dissertations

This dissertation focuses on specific aspects of the technical design and operation of a `smart' distribution system incorporating new technology in the design process. The main purpose of this dissertation is to propose new algorithms in order to achieve a more reliable and economic distribution system.

First, a general approach based on Mixed Integer Programming (MIP) is proposed to formulate the reconfiguration problem for a radial/weakly meshed distribution network or restoration following a fault. Two objectives considered in this study are to minimize the active power loss, and to minimize the number of switching operations with respect to operational constraints, …

Position-Adaptive Localization Of An Electro-Magnetic Source Using Static And Mobile Wireless Sensor Networks, Miguel D. Gates

Doctoral Dissertations

We present new results in detection and localization of a hidden emitter using Wireless Sensor Networks (WSNs). While this type of problem has been explored extensively, this research combines multiple dynamics, such as mobility and adaptation, to extend the value beyond the typical search mission. Using Micro-Aerial Vehicles (MAVs), in conjunction with multiple static wireless sensor nodes, we create a hybrid sensor network capable of detection and localization of a hidden electro-magnetic (EM) emitter.

In order to localize the emitter, a Received Signal Strength Indicator (RSSI) is used as an approximation of distance from the transmitter to the revolving receivers. …

Advanced Studies On Locational Marginal Pricing, Yanli Wei

Doctoral Dissertations

The effectiveness and economic aspect of Locational Marginal Price (LMP) formulation to deal with the power trading in both Day-Ahead (DA) and Real-Time (RT) operation are the focus of not only the system operator but also numerous market participants. In addition, with the ever increasing penetration of renewable energy being integrated into the grid, uncertainty plays a larger role in the process of market operation. The study is carried out in four parts.

In the first part, the mathematical programming models, which produce the generation dispatch solution for the Ex Post LMP, are reviewed. The existing approach fails to meet …

Motion Segmentation Aided Super Resolution Image Reconstruction, Muharrem Mercimek

Doctoral Dissertations

This dissertation addresses Super Resolution (SR) Image Reconstruction focusing on motion segmentation. The main thrust is Information Complexity guided Gaussian Mixture Models (GMMs) for Statistical Background Modeling. In the process of developing our framework we also focus on two other topics; motion trajectories estimation toward global and local scene change detections and image reconstruction to have high resolution (HR) representations of the moving regions. Such a framework is used for dynamic scene understanding and recognition of individuals and threats with the help of the image sequences recorded with either stationary or non-stationary camera systems.

We introduce a new technique called …

Control Of Solar Photovoltaic (Phv) Power Generation In Grid-Connected And Islanded Microgrids, Sarina Adhikari

Doctoral Dissertations

With the ever increasing electricity demand, fast depletion of fossil fuel and the growing trend towards renewable energy resources, the integration of green distributed energy resources (DERs) such as solar photovoltaic (PhV) generation and wind power in the utility grid is gaining high popularity in the present years. The capability of these modular generators needs to be harnessed properly in order to achieve the maximum benefit out of such integrated systems. Most DERs are connected to the utility grid or microgrids with the help of power electronics interface. They are capable of producing both active and reactive power with the …

Vehicle-To-Grid (V2g) Reactive Power Operation Analysis Of The Ev/Phev Bidirectional Battery Charger, Mithat Can Kisacikoglu

Doctoral Dissertations

More battery powered electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) will be introduced to the market in 2013 and beyond. Since these vehicles have large batteries that need to be charged from an external power source or directly from the grid, their charging circuits and grid interconnection issues are garnering more attention.

It is possible to incorporate more than one operation mode in a charger by allowing the power to flow bidirectionally. Usually, the bidirectional power transfer stands for two-way transfer of active power between the charger and the grid. The general term of sending active power from …

Unmanned Ground Vehicle Navigation And Coverage Hole Patching In Wireless Sensor Networks, Guyu Zhang

Doctoral Dissertations

This dissertation presents a study of an Unmanned Ground Vehicle (UGV) navigation and coverage hole patching in coordinate-free and localization-free Wireless Sensor Networks (WSNs). Navigation and coverage maintenance are related problems since coverage hole patching requires effective navigation in the sensor network environment. A coordinate-free and localization-free WSN that is deployed in an ad-hoc fashion and does not assume the availability of GPS information is considered. The system considered is decentralized and can be self-organized in an event-driven manner where no central controller or global map is required.

A single-UGV, single-destination navigation problem is addressed first. The UGV is equipped …

Optimized Techniques For Real-Time Microwave And Millimeter Wave Sar Imaging, Joseph T. Case

Doctoral Dissertations

"Microwave and millimeter wave synthetic aperture radar (SAR)-based imaging techniques, used for nondestructive evaluation (NDE), have shown tremendous usefulness for the inspection of a wide variety of complex composite materials and structures. Studies were performed for the optimization of uniform and nonuniform sampling (i.e., measurement positions) since existing formulations of SAR resolution and sampling criteria do not account for all of the physical characteristics of a measurement (e.g., 2D limited-size aperture, electric field decreasing with distance from the measuring antenna, etc.) and nonuniform sampling criteria supports sampling below the Nyquist rate. The results of these studies demonstrate optimum sampling given …

Advances In Blind Source Separation, Christopher Osterwise

Doctoral Dissertations

"Blind Source Separation (BSS) is a classic problem that attempts to separate unknown sources from observed mixtures. A common framework of this is the Cocktail Party problem, where multiple individuals speaking in a noisy room are recorded by a configuration of microphones, with the challenge being to split the observed signals into individual conversations. This dissertation covers the evaluation of an existing algorithm known as Cascaded ICA with Intervention Alignment (CICAIA), the establishment of a new parameter for characterizing blind mixtures, and three new algorithms, of which two are capable of separating any number of sources given more microphones than …

Source Reconstructions For Ic Radiated Emissions Based On Magnitude-Only Near-Field Scanning, Ji Zhang

Doctoral Dissertations

"In this dissertation, a source reconstruction method is proposed to model the emission behavior of an IC by using magnitude-only information during near-field scanning. The phase-retrieval is accomplished during the back-forth iterations between two scanning planes of different heights. The magnitudes of fields on two planes of different heights are recorded and used to constrain the amplitude of the calculated fields during iterations. Three essential transformations among dipoles and fields are continued at each iteration step, until the convergence condition is achieved. The proposed algorithm has been verified by using a set of dipole-array as the original emitting sources, and …

Common Mode Current Estimation For Cable Bundle Inside A Vehicle, Dazhao Liu

Doctoral Dissertations

"In the Section 1, it introduces a methodology to simulate the currents and fields during an air discharge ESD into a product by combining a linear description of the behavior of the DUT with a non-linear arc resistance equation. The most commonly used test standard IEC 61000-4-2 requires using contact mode discharges to metallic surfaces and air discharge mode to non-conducting surfaces. This paper proposes a method that combines the linear ESD generator full wave model and the non-linear arc model to simulate currents and fields in air discharge mode. In Section 2, when simulating surface and thin wire structures, …

Detecting And Locating Electronic Devices Using Their Unintended Electromagnetic Emissions, Colin Stagner

Doctoral Dissertations

"Electronically-initiated explosives can have unintended electromagnetic emissions which propagate through walls and sealed containers. These emissions, if properly characterized, enable the prompt and accurate detection of explosive threats. The following dissertation develops and evaluates techniques for detecting and locating common electronic initiators. The unintended emissions of radio receivers and microcontrollers are analyzed. These emissions are low-power radio signals that result from the device's normal operation. In the first section, it is demonstrated that arbitrary signals can be injected into a radio receiver's unintended emissions using a relatively weak stimulation signal. This effect is called stimulated emissions. The performance of stimulated …

Data Fusion Techniques For Nondestructive Evaluation And Medical Image Analysis, Soumya De

Doctoral Dissertations

"Data fusion is a technique for combining data obtained from multiple sources for an enhanced detection or decision. Fusion of data can be done at the raw-data level, feature level or decision level. Applications of data fusion include defense (such as battlefield surveillance and autonomous vehicle control), medical diagnosis and structural health monitoring. Techniques for data fusion have been drawn from areas such as statistics, image processing, pattern recognition and computational intelligence. This dissertation includes investigation and development of methods to perform data fusion for nondestructive evaluation (NDE) and medical imaging applications. The general framework for these applications includes region-of-interest …

Integration Of Nanoporous Zeolite With Optical Fiber Devices For Chemical Sensing, Xinwei Lan

Doctoral Dissertations

"Label-free optical fiber chemical sensors have provoked significant research interest in recent years due to their unique advantages of small size, low cost, potential for distributed sensing, capability of in situ and remote operation, and tolerance to harsh environments. However, existing optical fiber chemical sensors lack the desired sensitivity and specificity for many applications such as chemical and biological analysis, industrial process control, environmental monitoring, and national security.

The dissertation summarizes our research efforts and results in functional integration of nanoporous zeolites with optical fiber devices for development of label-free optical fiber chemical sensors with high sensitivity and selectivity. Fundamental …

Topics In Voice Echo Cancellation, Pratik Vijay Shah

Doctoral Dissertations

"Acoustic echo cancellation (AEC) is a well studied problem. The underlying assumption in most echo cancellation solutions is that the echo path following the reference signal is completely linear. However, in many handheld devices, the echo path following the reference signal is nonlinear. The reason for this nonlinearity in the echo path is the use of smaller and cheaper loudspeakers. In order to cut the manufacturing cost, device manufactures use cheaper loudspeakers such that they satisfy the carrier specifications. Such loudspeaker can be easily over driven in to their nonlinear region and thus add nonlinearities to the downlink path. This …

Inverter Design And Analysis Using Multiple Reference Frame Theory, Luke Dale Watson

Doctoral Dissertations

"Multiple reference frame theory allows for periodically time varying signals to be represented as a set of dc signals. In other words, every periodic signal can be expanded into a Fourier series representation. By modeling an inverter connected to a boost maximum power point tracker (MPPT) in this manner, frequency transfer properties can be preserved and harmonics throughout the system can be predicted. A state space model taking into account the dc and fundamental grid frequency is presented and used to optimize the controller gains of the system. Using information from the dq-axis values of the measured grid current and …

Finite-Horizon Optimal Control Of Linear And A Class Of Nonlinear Systems, Qiming Zhao

Doctoral Dissertations

"Traditionally, optimal control of dynamical systems with known system dynamics is obtained in a backward-in-time and offline manner either by using Riccati or Hamilton-Jacobi-Bellman (HJB) equation. In contrast, in this dissertation, finite-horizon optimal regulation has been investigated for both linear and nonlinear systems in a forward-in-time manner when system dynamics are uncertain. Value and policy iterations are not used while the value function (or Q-function for linear systems) and control input are updated once a sampling interval consistent with standard adaptive control. First, the optimal adaptive control of linear discrete-time systems with unknown system dynamics is presented in Paper I …

Model Based Fault Diagnosis And Prognosis Of Nonlinear Systems, Hasan Ferdowsi

Doctoral Dissertations

"Rapid technological advances have led to more and more complex industrial systems with significantly higher risk of failures. Therefore, in this dissertation, a model-based fault diagnosis and prognosis framework has been developed for fast and reliable detection of faults and prediction of failures in nonlinear systems. In the first paper, a unified model-based fault diagnosis scheme capable of detecting both additive system faults and multiplicative actuator faults, as well as approximating the fault dynamics, performing fault type determination and time-to-failure determination, is designed. Stability of the observer and online approximator is guaranteed via an adaptive update law. Since outliers can …

Synthetic Aperture Radar-Based Techniques And Reconfigurable Antenna Design For Microwave Imaging Of Layered Structures, Mojtaba Fallahpour

Doctoral Dissertations

"In the past several decades, a number of microwave imaging techniques have been developed for detecting embedded objects (targets) in a homogeneous media. New applications such as nondestructive testing of layered composite structures, through-wall and medical imaging require more advanced imaging systems and image reconstruction algorithms (post-processing) suitable for imaging inhomogeneous (i.e., layered) media. Currently-available imaging algorithms are not always robust, easy to implement, and fast. Synthetic aperture radar (SAR) techniques are some of the more prominent approaches for image reconstruction when considering low loss and homogeneous media. To address limitations of SAR imaging, when interested in imaging an embedded …

Dynamic Modeling, Stability Analysis, And Controller Design For Dc Distribution Systems, Reza Ahmadi

Doctoral Dissertations

"The dc distribution systems or dc microgrids are known to be best suited for integration of renewable energy sources into the current power grid and are considered to be the key enabling technology for the development of future smart grid. Dc microgrids also benefit from better current capabilities of dc power lines, better short circuit protection, and transformer-less conversion of voltage levels, which result in higher efficiency, flexibility, and lower cost. While the idea of using a dc microgrid to interface distributed energy sources and modern loads to the power grid seems appealing at first, several issues must be addressed …