Engineering Commons^™

Optimal Sizing And Location Of Static And Dynamic Reactive Power Compensation, Wenjuan Zhang

Doctoral Dissertations

The key of reactive power planning (RPP), or Var planning, is the optimal allocation of reactive power sources considering location and size. Traditionally, the locations for placing new Var sources were either simply estimated or directly assumed. Recent research works have presented some rigorous optimization-based methods in RPP. Different constraints are the key of various optimization models, identified as Optimal Power Flow (OPF) model, Security Constrained OPF (SCOPF) model, and Voltage Stability Constrained OPF model (VSCOPF).

First, this work investigates the economic benefits from local reactive power compensation including reduced losses, shifting reactive power flow to real power flow, and …

Electro-Thermal Modeling Of Sic Power Electronic Systems, Hui Zhang

Doctoral Dissertations

As the development of Silicon (Si) semiconductor technology slows down due to its material limitations, more and more attention is being paid to wide bandgap material based semiconductor technology. Silicon Carbide (SiC) has been widely recognized as the material for next generation power electronic devices. However, a great deal of work needs to be done before SiC power devices can be widely applied. This dissertation addresses this need and has conducted research on the modeling of SiC power electronic system. More specifically, a method for system modeling of a SiC power system based on basic physics and device tests is …

Stochastic Signal Processing And Power Control For Wireless Communication Systems, Mohammed Mohsen Olama

Doctoral Dissertations

This dissertation is concerned with dynamical modeling, estimation and identification of wireless channels from received signal measurements. Optimal power control algorithms, mobile location and velocity estimation methods are developed based on the proposed models.

The ultimate performance limits of any communication system are determined by the channel it operates in. In this dissertation, we propose new stochastic wireless channel models which capture both the space and time variations of wireless systems. The proposed channel models are based on stochastic differential equations (SDEs) driven by Brownian motions. These models are more realistic than the time invariant models encountered in the literature …

Image Segmentation Using Pde, Variational, Morphological And Probabilistic Methods, Yongsheng Pan

Doctoral Dissertations

The research in this dissertation has focused upon image segmentation and its related areas, using the techniques of partial differential equations, variational methods, mathematical morphological methods and probabilistic methods. An integrated segmentation method using both curve evolution and anisotropic diffusion is presented that utilizes both gradient and region information in images. A bottom-up image segmentation method is proposed to minimize the Mumford-Shah functional. Preferential image segmentation methods are presented that are based on the tree of shapes in mathematical morphologies and the Kullback-Leibler distance in information theory. A thorough evaluation of the morphological preferential image segmentation method is provided, and …

Design Of A Cost-Efficient Reconfigurable Pipeline Adc, Wenchao Qu

Doctoral Dissertations

Power budget is very critical in the design of battery-powered implantable biomedical instruments. High speed, high resolution and low power usually cannot be achieved at the same time. Therefore, a tradeoff must be made to compromise every aspect of those features. As the main component of the bioinstrument, high conversion rate, high resolution ADC consumes most of the power. Fortunately, based on the operation modes of the bioinstrument, a reconfigurable ADC can be used to solve this problem. The reconfigurable ADC will operate at 10-bit 40 MSPS for the diagnosis mode and at 8-bit 2.5 MSPS for the monitor mode. …

Study Of Interaction Between Indium Species And Dna In The Formation Of Dna -Templated Nanowires, Shivashankar Suryanarayanan

Doctoral Dissertations

A primary goal of semiconductor industry is to improve device performance and capability by downscaling feature size and upscaling packaging density. As optical-lithography, the mainstream technology for microfabrication, is being stretched to its limit, new unconventional fabrication techniques are being explored as alternatives. A "Bottom-up" approach for manufacturing is emerging as an answer to limitations posed by the traditional "Top-down" approach. Nanowires, bearing the potential of being the basic building blocks for such an approach, are gaining tremendous attention in nanoelectronics. Metal nanowires fabricated using DNA as templates have potential for precise control of length, diameter and positioning. However, wires …

Design And Development Of Microcantilever As A Platform For Moisture Sensing, Qi Chen

Doctoral Dissertations

Ultra-sensitive and selective moisture sensors are needed in various industries for processing control or environmental monitoring. As an outstanding sensor platform, microcantilevers have potential application in moisture detection due to their advantages, such as low-level moisture detection limits, high accuracy, quick response time, high reproducibility, good recovery rate and low in cost. Our research results will lead to the first of its kind for the commercialization of a microcantilever-based moisture sensor used for industrial and household applications. The novelty of the present work is the development of SiO2 and Si cantilevers, which were fabricated using developed processes and modified with …

Intrinsically Evolvable Artificial Neural Networks, Saumil Girish Merchant

Doctoral Dissertations

Dedicated hardware implementations of neural networks promise to provide faster, lower power operation when compared to software implementations executing on processors. Unfortunately, most custom hardware implementations do not support intrinsic training of these networks on-chip. The training is typically done using offline software simulations and the obtained network is synthesized and targeted to the hardware offline. The FPGA design presented here facilitates on-chip intrinsic training of artificial neural networks. Block-based neural networks (BbNN), the type of artificial neural networks implemented here, are grid-based networks neuron blocks. These networks are trained using genetic algorithms to simultaneously optimize the network structure and …

Analysis Of Simulated Electromyography (Emg) Signals Using Integrated Computer Muscle Model, Mohammad Abdul Ahad

Doctoral Dissertations

Introduction

Electromyography (EMG) is a technique used to study the activity of muscle through detection and analysis of the electrical signals generated during muscular contractions. Electromyographic activity is recorded from skeletal muscles to obtain information about their anatomy and physiology. Electromyography, in interplay with various anatomical techniques, provides the present knowledge of the structural organization and the nervous control of muscle. EMG is the prime source of information about the status of the neuromuscular system, and EMG has developed into a diagnostic tool that allows the clinician to follow changes in nerve and muscle caused by neuromuscular diseases.

EMG provides …

Polymer Light Emitting Diodes Based On Polyfluorenes, Quishu Zhang

Doctoral Dissertations

This dissertation is devoted to the study on Polymer Light-Emitting Diodes (PLEDs) based on polyfluorenes (PFs), a promising class of semiconductive polymers for Light-Emitting Diode (LED) applications. Recently Light Emitting Polymers (LEPs) have clearly made their entry into display technology by virtue of their potential application for large-area flat-panel displays with the advantages of low cost, wide viewing angle, fast switching time, high efficiency, low driving voltage, as well as their flexibility and adaptability. Compared to inorganic materials, the efficiency of PLEDs is, however, still low. And for the application of PFs in PLEDs, an undesired longwavelength emission band is …

Fabrication And Application Of Conducting Polymer Micro- And Nano-Patterns, Anirban Chakraborty

Doctoral Dissertations

Conducting polymers, since their discovery, have attracted significant attention due to their promise of replacing silicon and metals in building devices. They have been shown to have wide applications for biological and chemical sensing as well as for electronic devices. Previous and current efforts have concentrated on building devices of a specific function. When multiple micropatterns of different conducting polymers are fabricated on a common substrate, a versatile microsystem can be envisioned. The existing conducting polymer patterning techniques present some technical challenges of degradation, low throughput, low resolution, depth of field, and residual layer in producing conducting polymer microstructures. To …

Nonlinear Dynamical Analysis Of Brain Electrical Activity Due To Exposure To Weak Environmentally Relevant Electromagnetic Fields, Erik Alfonso Nilsen

Doctoral Dissertations

The reports dealing with the effects of weak electromagnetic fields (EMFs) on brain electrical activity have been inconsistent. We suspected that the use of linear models and their associated methods accounted for some of the variability, and we explored the issue by using a novel approach to study the effects of EMFs on the electroencephalogram (EEG) from rabbits and humans. The EEG was embedded in phase space and local recurrence plots were calculated and quantified to permit comparisons between exposed and control epochs from individual subjects. Statistically significant alterations in brain activity were observed in each subject when exposed to …

Computer Simulation And Human Experiment On The Laplacian Electrocardiogram (Ecg), Ting Chen

Doctoral Dissertations

The electrocardiogram (ECG) provides useful global temporal assessment of cardiac activity, but has limited spatial capabilities. Laplacian electrocardiogram (LECG) and body surface Laplacian mapping (BSLM), improvements over ECG provides high spatiotemporal distributed information about cardiac electrical activation.

This project was divided into two parts: computer simulation and human experiment. In the computer simulation, a comparison of the performance of the tripolar and bipolar as well as spline LECG and BSLMs for localizing and imaging the cardiac electrical activation has been investigated. A simple planar surface model and a simplified eccentric heart-torso sphere-cylinder homogeneous volume conductor model were developed. Multiple dipoles …

An Intermediate-Layer Lithography Method For Producing Metal Micron/Nano Patterns And Conducting Polymer-Based Microdevices, Xinchuan Liu

Doctoral Dissertations

Metals have been widely used in the areas of integration circuit (IC) and microelectromechanical systems (MEMS) fields as materials for gates, contact pads, interconnects, corrosion resistance coatings, rectifying contacts, redundancy memories, heating elements, mechanical parts, magnetic component, etc. due to their good properties, such as high electrical conductivity and good thermal conductivity. Conducting polymers, because of their promising potential to replace silicon and metals in building devices, have attracted great attention in recent decades.

Traditional photolithography methods are often used to pattern metals and conducting polymers. However, it cannot be used to fabricate nano patterns because the minimum feature size …

A Programmable Frequency Divider Having A Wide Division Ratio Range, And Close-To-50% Output Duty-Cycle, Mo Zhang

Doctoral Dissertations

In Radio Frequency (RF) integrated circuit design field, programmable dividers are getting more and more attentions in recent years. A programmable frequency divider can divide an input frequency by programmable ratios [1]. It is a key component of a frequency synthesizer. It also can be used to generate variable clock-signals for: switched-capacitor filters (SCFs), digital systems with different power-states, as well as multiple clock-signals on the same system-on-a-chip (SOC). These circuits need high performance programmable frequency dividers, operating at high frequencies and having wide division ratio ranges, with binary division ratio controls and 50% output duty-cycle.

Different types of programmable …

Modular Dc-Dc Converters, Faisal Habib Khan

Doctoral Dissertations

DC-DC converter is one of the mostly used power electronic circuits, and it has applications in various areas ranging from portable devices to aircraft power system. Various topologies of dc-dc converters are suitable for different applications. In high power applications such as the bi-directional dc-dc converter for dual bus system in new generation automobiles, several topologies can be considered as a potential candidate. Regardless of the topology used for this application, the reliability of the converter can be greatly enhanced by introducing redundancy of some degree into the system. Using redundancy, uninterrupted operation of the circuit may be ensured when …

Process And Temperature Compensated Wideband Injection Locked Frequency Dividers And Their Application To Low-Power 2.4-Ghz Frequency Synthesizers, Rajagopal Vijayaraghavan

Doctoral Dissertations

There has been a dramatic increase in wireless awareness among the user community in the past five years. The 2.4-GHz Industrial, Scientific and Medical (ISM) band is being used for a diverse range of applications due to the following reasons. It is the only unlicensed band approved worldwide and it offers more bandwidth and supports higher data rates compared to the 915-MHz ISM band. The power consumption of devices utilizing the 2.4-GHz band is much lower compared to the 5.2-GHz ISM band. Protocols like Bluetooth and Zigbee that utilize the 2.4-GHz ISM band are becoming extremely popular.

Bluetooth is an …

Fault Diagnostic System For Cascaded H-Bridge Multilevel Inverter Drives Based On Artificial Intelligent Approaches Incorporating A Reconfiguration Technique, Surin Khomfoi

Doctoral Dissertations

A fault diagnostic and reconfiguration system in a multilevel inverter drive (MLID) using artificial intelligent based techniques is developed in this dissertation. Output phase voltages of a MLID can be used as valuable information to diagnose faults and their locations. It is difficult to diagnose a MLID system using a mathematical model because MLID systems consist of many switching devices and their system complexity has a nonlinear factor. Therefore, a neural network (NN) classification is applied to the fault diagnosis of a MLID system. Multilayer perceptron (MLP) networks are used to identify the type and location of occurring faults. The …

Neural Network Control Of Nonstrict Feedback And Nonaffine Nonlinear Discrete-Time Systems With Application To Engine Control, Jonathan B. Vance

Doctoral Dissertations

"In this dissertation, neural networks (NN) approximate unknown nonlinear functions in the system equations, unknown control inputs, and cost functions for two different classes of nonlinear discrete-time systems. Employing NN in closed-loop feedback systems requires that weight update algorithms be stable...Controllers are developed and applied to a nonlinear, discrete-time system of equations for a spark ignition engine model to reduce the cyclic dispersion of heat release"--Abstract, page iv.

Advanced Controller Design Using Neural Networks For Nonlinear Dynamic Systems With Application To Micro/Nano Robotics, Qinmin Yang

Doctoral Dissertations

"The dissertation focuses on neural network (NN) control designs for nonlinear systems with application to micro/nano robotic. Critical problems in nano scale including thermal drift are also addressed"--Abstract, page iv.

Nonlinear Optimization Approach For Upfc Power Flow Control And Voltage Security: Sufficient System Constraints For Optimality, Radha P. Kalyani

Doctoral Dissertations

"This dissertation provides a nonlinear optimization algorithm for the long term control of Unified Power Flow Controller (UPFC) to remove overloads and voltage violations by optimized control of power flows and voltages in the power network. It provides a control strategy for finding the long term control settings of one or more UPFCs by considering all the possible settings and all the (N-1) topologies of a power network. Also, a simple evolutionary algorithm (EA) has been proposed for the placement of more than one UPFC in large power systems"--Abstract, page iv.

Simple And Efficient Solutions To The Problems Associated With Acoustic Echo Cancellation, Asif Iqbal Mohammad

Doctoral Dissertations

"This dissertation is a collection of papers that addresses several important problems associated with acoustic/line echo cancellation (AEC/LEC), specifically double-talk and echo-path change detection. A double-talk detector is used to freeze AEC filter's adaptation during periods of near-end speech. This dissertation presents three different novel double-talk detection schemes. Simulations demonstrate the efficiency of the proposed algorithms"--Abstract, page iii.

Detection Algorithms For Spatial Data, Spandan Tiwari

Doctoral Dissertations

"This dissertation addresses the problem of anomaly detection in spatial data. The problem of landmine detection in airborne spatial data is chosen as the specific detection scenario. The first part of the dissertation deals with the development of a fast algorithm for kernel-based non-linear anomaly detection in the airborne spatial data. The original Kernel RX algorithm, proposed by Kwon et al. [2005a], suffers from the problem of high computational complexity, and has seen limited application. With the aim to reduce the computational complexity, a reformulated version of the Kernel RX, termed the Spatially Weighted Kernel RX (SW-KRX), is presented. It …

New Techniques To Improve Power Quality And Evaluate Stability In Modern All-Electric Naval Ship Power Systems, Peng Xiao

Doctoral Dissertations

"This dissertation focuses on two crucial issues in the design and analysis of the power electronic systems on modern all-electric naval ships, i.e., power quality control and stability evaluation. It includes three papers that deal with active power filter topology, active rectifier control, and impedance measurement techniques, respectively. To mitigate harmonic currents generated by high-power high-voltage shipboard loads such as propulsion motor drives, the first paper proposes a novel seven-level shunt active power filter topology, which utilizes tapped reactors for parallel operations of switching devices. The multi-level system has been implemented in both regular digital simulation and real-time digital simulator …

Bga Footprints Modeling And Physics Based Via Models Validation For Power And Signal Integrity Applications, Giuseppe Selli

Doctoral Dissertations

"Modeling and simulating the multi-scale nature of a power distribution network (PDN) is essential to ensure the correct functioning of the devices connected to it. Simple parallel-plate sections constitute the core of these PDN geometries, together with sections where a large number of holes and vias are present, as in the case of a BGA footprint. Employing a divide-and-conquer approach allows for the modeling of these geometries separately, i.e., 3-D full wave solvers for the sections with holes and vias, and a cavity model approach, for the simple parallel-plate structures. Also, equivalent circuit models can be obtained for time-domain and …

Mobile Array Designs With Anserlin Antennas And Efficient, Wide-Band Peec Models For Interconnect And Power Distribution Network Analysis, Michael A. Cracraft

Doctoral Dissertations

"A mobile, wide-band antenna system has been developed around the ANSERLIN antenna element and a 3-dB splitter design. The size of the antenna elements was reduced over previous versions by introducing dielectric substrates. Additionally, new variations of the antenna were designed to influence radiation characteristics. To further reduce the number of components in the array, a very low profile splitter was designed and mounted below one of the antenna elements, doubling as the return plane for the antenna. The partial-element equivalent circuit (PEEC) method has been used for 3D interconnect analysis and numerous other applications. Being based on the same …

Data Fusion Techniques For Health Monitoring Of Aging Aircraft And Skin Cancer Detection, Kapil Gupta

Doctoral Dissertations

"Data fusion is generally practiced to enhance decision or inference making capability. Sensor and information source data may often be corrupted by noise or other factors. Data fusion can be used to improve sensor and/or information source data quality and reliability and improve detection accuracy. There are several types of data fusion, including raw data level, feature level, and decision level.

This work presents the investigation and development of image and signal processing, computational intelligence, fuzzy logic, and statistical techniques for different types of data fusion for a varied range of applications. Raw data and decision level fusion approaches are …