Electrical and Computer Engineering Commons^™

Ultrafast Time Domain Optics Of Single-Cycle Laser Pulse Interaction With Materials, Ufuk Parali

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, interaction of an ultrashort single-cycle pulse (USCP) with a bound electron without ionization is studied for the first time. For a more realistic mathematical description of USCPs, Hermitian polynomials and combination of Laguerre functions are used for two different single-cycle excitation cases. These single-cycle pulse models are used as driving functions for the classical approach to model the interaction of a bound electron with an applied field. Two different new novel time domain modification techniques are developed for modifying the classical Lorentz damped oscillator model in order to make it compatible with the USCP excitation. In the …

Modeling And Simulation Of Tunable Photonic Crystals, Weiqing Yang

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Photonic crystals (PhCs) have wavelength scale periodically alternating refractive indexes. Photon in such structures is subject to strong scattering, experiencing distinctive redistribution of energy, yielding interesting properties such as photonic band gaps, field enhancement, strong nonlinear optic effects and photon confinement. The modified fields also alter the propagation of light beams. By proper setup, super collimation could be realized in PhCs where beams can travel long distance without spreading, while no waveguide structure is used. Redirection of light can extend the refraction to negative range, without violating physics rules. This distinguished phenomenon has been envisioned as the core mechanism for …

Generalized Ellipsometry On Sculptured Thin Films Made By Glancing Angle Deposition, Daniel Schmidt

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, physical properties of highly optically and magnetically anisotropic metal sculptured thin films made by glancing angle deposition are presented. Predominantly, the determination of optical and magneto-optical properties with spectroscopic generalized Mueller matrix ellipsometry and homogenization approaches is discussed. Nomenclatures are proposed to unambiguously identify the sculptured thin film geometry.

Generalized ellipsometry, a non-destructive optical characterization technique, is employed to determine geometrical structure and anisotropic dielectric properties of highly spatially coherent three-dimensionally nanostructured thin films in the spectral range from 400 to 1700 nm. The analysis of metal slanted columnar thin films (F1-STFs) deposited at glancing angle ( …

Energy Storage And Management For A Small Series Plug-In Hybrid Electric Vehicle, Liqin Ni

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Plug-in hybrid electric vehicles (PHEVs) are gaining increasing interest for both residential and commercial transportation applications. In PHEV design, energy storage system (EES) is a critical component which will impact the overall design efficiency, performance, cost and etc. This dissertation aims to design an advanced energy storage system for a small plug-in hybrid electric vehicle, whose performance will approach very closely to the optimal possible, in terms of energy efficiency and acceleration, for passenger road vehicles application. Moreover, practical automotive requirements are considered during ESS design, such as cost, life time, safety and volume.

This dissertation utilizes ultracapacitors in conjunction …

Identification Of Psychological Patterns Using Neural Networks Approach, Panpan Hu

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Recent studies have shown that Artificial Neural Networks (ANNs) are suitable for recognizing patterns in the medical area. However, no study has been done to show whether or not they are also effective in the psychological area. In this study, ANNs are developed for six psychological cases related to sociobehavioral functioning. The cases are independent living skill deficits, disorder management deficits, occupational skill deficits, social skill deficits, dysregulation of anger/aggression, and substance abuse. Two models, one based on a backpropagation algorithm and the other based on a posteriori probability approach, were developed. The models were tested using data from 118 …

A Single-Chip Ultra-Wideband Based Wireless Sensor Network Node, Nathan R. Schemm

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

This dissertation presents the design of a next-generation wireless sensor network node. The node incorporates many new and innovative technologies such as an ultra-wideband radio which allows very low-energy communication, a low-power radiation detection front end, and an efficient implementation of dynamic voltage scaling which improves the energy efficiency of the integrated processor. The complete design is integrated on a single chip for maximum power savings and minimal size.

The ultra-wideband transceiver includes many novel techniques to produce a receiver with low power consumption and fast and accurate packet acquisition and reception. These include the use of a standard symmetric …

A Comparison Of Induction Motor Starting Methods Being Powered By A Diesel-Generator Set, Adam John Wigington

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Starting induction motors on isolated or weak systems is a highly dynamic process that can cause motor and load damage as well as electrical network fluctuations. Mechanical damage is associated with the high starting current drawn by a ramping induction motor. In order to compensate the load increase, the voltage of the electrical system decreases. Different starting methods can be applied to the electrical system to reduce these and other starting method issues. The purpose of this thesis is to build accurate and usable simulation models that can aid the designer in making the choice of an appropriate motor starting …

Maintenance Optimization For Substations With Aging Equipment, Haifeng Ge

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Today’s electric utilities are confronted with a myriad of challenges that include aging infrastructure, enhanced expectation of reliability, reduced cost, and coping effectively with uncertainties and changing regulation requirements. Utilities rely on Asset Management programs to manage inspections and maintenance activities in order to control equipment conditions. However, development of strategies to make sound decisions in order to effectively improve equipment and system reliability while meeting constraints such as a maintenance budget is a challenge.

The primary objective of this dissertation is to develop models and algorithms to study the impact of maintenance toward equipment/system reliability and economic cost, and …

Dc/Dc Converter For A Small Scale Wind Hydrogen System, Joel M. Jacobs

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

An electronic converter is designed for an isolated renewable energy system. In this system, energy produced by a small wind turbine is used to extract hydrogen from water. Unique aspects of this application that affect the performance of the converter will be defined. Design considerations of the individual components will be discussed. Calculations on performance and validation of those calculations are also presented. Lastly, an economic analysis of the produced hydrogen will be performed.

Finite Tree-Based Decoding Of Low-Density Parity-Check Codes, Eric T. Psota

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Low-density parity-check codes are commonly decoded using iterative message-passing decoders, such as the min-sum and sum-product decoders. Computer simulations demonstrate that these suboptimal decoders are capable of achieving low probability of bit error at signal-to-noise ratios close to capacity. However, current methods for analyzing the behavior of the min-sum and sum-product decoders fails to produce usable bounds on the probability of bit error. Thus, the resulting probability of bit error when using these decoders remains largely unknown for signal-to-noise ratios beyond the reach of simulation. For this reason, it is worth considering alternative methods for decoding low-density parity-check codes. New …

Modeling Biological Structures Via Abstract Grammars To Solve Common Problems In Computational Biology, David J. Russell

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Grammars are generally understood to be the set of rules that define the relationships between elements of a language. However, grammars can also be used to elucidate structural relationships within sequences constructed from any finite alphabet. In this work abstract grammars are used to model the primary and secondary structures present in biological data. These grammar models are inferred and applied to efficiently solve various sequence analysis problems in computational biology, including multiple sequence alignment, fragment assembly, database redundancy removal, and structural prediction.

The primary structures, or sequential ordering of symbols, of biological data are first modeled with Lempel-Ziv (LZ) …

Growth And Characterization Of Silicon Carbide Thin Films Using A Nontraditional Hollow Cathode Sputtering Technique, James Huguenin-Love

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Silicon carbide (SiC) is considered a suitable candidate for high-power, high-frequency devices due to its wide bandgap, high breakdown field, and high electron mobility. It also has the unique ability to synthesize graphene on its surface by subliming Si during an annealing stage. The deposition of SiC is most often carried out using chemical vapor deposition (CVD) techniques, but little research has been explored with respect to the sputtering of SiC.

Investigations of the thin film depositions of SiC from pulse sputtering a hollow cathode SiC target are presented. Although there are many different polytypes of SiC, techniques are discussed …

Experimental Investigation Of Dielectric Barrier Impact On Breakdown Voltage Enhancement Of Copper Wire-Plane Electrode Systems, Elham Foruzan, M. Ziaee-Nezhad, A. A. Shayegani-Akmal, K. Niayesh

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Non-pressurized air is extensively used as basic insulation media in medium / high voltage equipments. An inherent property of air-insulated designs is that the systems tend to become physically large. Application of Dielectric barrier can increase the breakdown voltage and therefore decrease the size of the equipments.

In this paper, the impact of dielectric barrier on breakdown voltage enhancement of a copper wire-plane system is investigated. For this purpose, the copper wire is covered with different dielectric materials. Depending on the air gap and dielectric strength of the barrier the breakdown can be initiated in the solid or gas dielectric. …

Design Of An Integrated Starter-Alternator For A Series Hybrid Electric Vehicle: A Case Study In Axial Flux Permanent Magnet Machine Design, Jessica L. Colton

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

This thesis details the design of an electric machine to perform as both a starter and alternator in a series hybrid electric vehicle. The focus of the work is on practical design aspects specific to single-sided axial flux permanent magnet machines with non-overlapped windings. First, a characterization of the rotor losses in these machine types is presented through experimental validation of finite element analysis estimates. The approaches taken to model the axial flux geometry, especially in two-dimensions, are detailed, and the difficult issue of validating the finite element analysis estimates with experimental data is addressed with a prototype 24-slot, 20-pole …