Engineering Commons^™

An Invariance Transformation Algorithm For Defect Characterization Of Ultrasonic Signals For The Nondestructive Evaluation Of Concrete, Michael Dominic Ciocco

Theses and Dissertations

Nondestructive evaluation (NDE) techniques offer cost-effective strategies for monitoring the integrity of a variety of civil infrastructure, such as natural gas and sewer pipelines, without the need to take the system off-line. However, interpretation of NDE signals in terms of the location, size, and shape of underlying flaws in the material being inspected is fraught with difficulty. Typically, variations in the testing signal due to operational parameters have created a significant challenge for defect characterization. This thesis proposes, develops, and validates a defect characterization algorithm that compensates for operational variables and maps the test signal to a visual defect profile. …

Automated Segmentation Of Radiodense Tissue In Digitized Mammograms Using A Constrained Neyman-Pearson Classifier, Jeremy Thomas Neyhart

Theses and Dissertations

Breast cancer is the second leading cause of cancer related mortality among American women. Mammography screening has emerged as a reliable non-invasive technique for early detection of breast cancer. The radiographic appearance of the female breast consists of radiolucent (dark) regions and radiodense (light) regions due to connective and epithelial tissue. It has been established that the percentage of radiodense tissue in a patient's breast can be used as a marker for predicting breast cancer risk. This thesis presents the design, development and validation of a novel automated algorithm for estimating the percentage of radiodense tissue in a digitized mammogram. …

Surface Modeling And Analysis Using Range Images: Smoothing, Registration, Integration, And Segmentation, Yiyong Sun

Doctoral Dissertations

This dissertation presents a framework for 3D reconstruction and scene analysis, using a set of range images. The motivation for developing this framework came from the needs to reconstruct the surfaces of small mechanical parts in reverse engineering tasks, build a virtual environment of indoor and outdoor scenes, and understand 3D images.

The input of the framework is a set of range images of an object or a scene captured by range scanners. The output is a triangulated surface that can be segmented into meaningful parts. A textured surface can be reconstructed if color images are provided. The framework consists …

Analysis And Characterization Of Single-Poly Floating Gate Devices In 0.35um Pdsoi Process, Chandra Sekhar Acharyulu Durisety

Masters Theses

The purpose of this thesis is to demonstrate a single-poly Floating Gate Device (FGD) in 0.35 m Partially Depleted Silicon On Insulator (PDSOI) process for use in analog circuits for post process trimming. Floating gate devices with different aspect ratios have been fabricated to facilitate this behavioral study in PDSOI process. Fundamentals of floating gate devices, the advantages and disadvantages of PDSOI compared to bulk CMOS with respect to single-poly floating gate devices are discussed. Various experiments on behavior and performance of threshold voltage have been conducted and its variation with programming/erasing time and amplitude has been analyzed. The single-poly …

Verification Of Intellectual Property Blocks Using Reconfigurable Hardware, Koay Teng Kuan

Masters Theses

The purpose of this thesis is to develop a procedure to verify intellectual property (IP)cores on the Pilchard platform which contains reconfigurable hardware. The hardware and tools used for the verification process are documented.

Two IP cores are used as examples of how the Pilchard design flow is to be applied. One core that does a simple logical function is implemented to serve as a demonstration of Pilchard read and write operations. To demonstrate the versatility of the hardware platform, a complex core that performs a Fast Fourier Transform operation was also implemented successfully.

Results from these IP implementations indicate …

State Of Charge Estimation For Batteries, Baskar Vairamohan

Masters Theses

In this thesis, a methodology to accurately estimate the state of charge (SOC ) of the batteries used in Hybrid Electric Vehicles (HEV) is proposed. A linear relationship exists between open circuit voltage (V_OC ) and SOC . In the proposed scheme, a system theory approach is employed to identify the open circuit voltage of the battery, from which the state of charge of the battery is determined. This method is very unique because it estimates the V_OC of the battery in the vehicle even under load conditions. A state variable approach yields a set of …

Online Determination Of The Steady-State Condition Of An Aerodynamic Test Article Mounted In A Wind Tunnel Test Cell, Martin Vincent Fette

Masters Theses

The Propulsion Wind Tunnel (PWT) facility at Arnold Engineering Development Center is devoted to aerodynamic and propulsion integration testing of large-scale aerodynamic models. Models of aircraft, missiles and rockets are tested at simulated altitude conditions from sea level to about 150,000 feet.

Before the data acquisition sequence, it is necessary to establish that the model position has stabilized following the movement of the test model to a new orientation. The existing procedure requires an extra delay, after moving the model, before data is acquired. This delay, however, may be more or less than necessary, resulting in wasted testing time or …

Electromagnetic Scattering From A Gap In A Magneto-Dielectric Coating On An Infinite Ground Plane, George R. Simpson

Theses and Dissertations

The electromagnetic scattering from a gap in a magneto-dielectric coating on an infinite ground plane is analyzed. In this context, the gap forms a break only in the magneto-dielectric slab coating while the ground plane is continuous and unbroken. Volume equivalence is used to convert the gap region to one containing unknown volumetric equivalent electric and magnetic currents. The equivalent problem then is one of these currents radiating in the presence of an unbroken grounded magneto-dielectric slab. A Green's function for this geometry is developed consisting of two terms: a direct coupling term and correction term to account for the …

Pattern Recognition For Electric Power System Protection, Yong Sheng

Doctoral Dissertations

The objective of this research is to demonstrate pattern recognition tools such as decision trees (DTs) and neural networks that will improve and automate the design of relay protection functions in electric power systems. Protection functions that will benefit from the research include relay algorithms for high voltage transformer protection (TP) and for high impedance fault (HIF) detection. A methodology, which uses DTs and wavelet analysis to distinguish transformer internal faults from other conditions that are easily mistaken for internal faults, has been developed. Also, a DT based solution is proposed to discriminate HIFs from normal operations that may confuse …

Automatic Target Recognition Classification System Evaluation Methodology, Christopher Brian Bassham

Theses and Dissertations

This dissertation research makes contributions towards the evaluation of developing Automatic Target Recognition (ATR) technologies through the application of decision analysis (DA) techniques. ATR technology development decisions should rely not only on the measures of performance (MOPs) associated with a given ATR classification system (CS), but also on the expected measures of effectiveness (MOEs). The purpose of this research is to improve the decision-makers in the ATR Technology development. A decision analysis framework that allows decision-makers in the ATR community to synthesize the performance measures, costs, and characteristics of each ATR system with the preferences and values of both the …

Adaptive Ds-Cdma Multiuser Detection For Time Variant Frequency Selective Rayleigh Fading Channel, Xin Tang

Dissertations

The current digital wireless mobile system such as IS-95, which is based on direct sequence Code Division Multiple Access (DS-CDMA) technology, will not be able to meet the growing demands for multimedia service due to low information exchanging rate. Its capacity is also limited by multiple accessed interference (MAI) signals.

This work focuses on the development of adaptive algorithms for multiuser detection (MUD) and interference suppression for wideband direct sequence code division multiple access (DS-CDMA) systems over time-variant frequency selective fading channels. In addition, channel acquisition and delay estimation techniques are developed to combat the uncertainty introduced by the wireless …

Multicast Outing Protocols And Architectures In Mobile Ad-Hoc Wireless Networks, Beongku An

Dissertations

The basic philosophy of personal communication services is to provide user-to-user, location independent communication services. The emerging group communication wireless applications, such as multipoint data dissemination and multiparty conferencing tools have made the design and development of efficient multicast techniques in mobile ad-hoc networking environments a necessity and not just a desire. Multicast protocols in mobile adhoc networks have been an area of active research for the past few years.

In this dissertation, protocols and architectures for supporting multicast services are proposed, analyzed and evaluated in mobile ad-hoc wireless networks. In the first chapter, the activities and recent advances are …

Em-Based Iterative Channel Estimation And Sequence Detection For Space-Time Coded Modulation, Zbigniew Baranski

Dissertations

Reliable detection of signals transmitted over a wireless communication channel requires knowledge of the channel estimate. In this work, the application of expectationmaximization (EM) algorithm to estimation of unknown channel and detection of space-time coded modulation (STCM) signals is investigated. An STCM communication system is presented which includes symbol interleaving at the transmitter and iterative EM-based soft-output decoding at the receiver. The channel and signal model are introduced with a quasi-static and time-varying Rayleigh fading channels considered to evaluate the performance of the communication system. Performance of the system employing Kalman filter with per-survivor processing to do the channel estimation …

On Chip Implement Of Deadlock Avoidance In Wormhole Networks, Kiran K. Gururaj

Theses

This thesis gives a detailed description of the Application Specific Integrated Circuit (ASIC) design to avoid deadlocks in Wormhole Networks. Deadlock avoidance is the most critical issue while considering wormhole networks and should be avoided by any routing protocol and algorithm. A novel architecture for the Turn Prohibition Based Routing (TPBR) protocol has been proved to be efficient and was developed as a part of this work. This architecture for implementing the algorithm is divided into three parts. The first part determines the order of selccuon of the nodes, in the network to run the algorithm. The second part deals …

High-Temperature, High-Resolution A/D Conversion Using 2nd- And 4th-Order Cascaded Σδ Modulation In 3.3-V 0.5Μm Sos-Cmos, M. Nance Ericson

Doctoral Dissertations

Sigma Delta Modulation is an oversampling technique commonly used in high-resolution analog-to-digital conversion. By employing oversampling and quantization noise shaping, the method allows very high-resolution conversion using low-resolution functional blocks. A multitude of architectural variations of this oversampled class of digitizers has been explored and reported in research literature for a wide variety of applications including seismic imaging, general low-bandwidth high-resolution instrumentation, audio conversion, and most recently high-speed communications.

Data conversion associated with seismic imaging has been recently dominated by this class of converters, though all data acquisition systems require environmental control, preventing placement of the digitizing electronics down-hole. The …

System Impact Of Silicon Carbide Power Electronics On Hybrid Electric Vehicle Applications, Burak Ozpineci

Doctoral Dissertations

The emergence of silicon carbide- (SiC-) based power semiconductor switches with their superior features compared with silicon (Si) based switches has resulted in substantial improvements in the performance of power electronics converter systems. These systems with SiC power devices are more compact, lighter, and more efficient, so they are ideal for high-voltage power electronics applications including hybrid electric vehicle (HEV) power converters.

In this dissertation, first, a power supply converter and a traction drive converter of an HEV are selected and then, the impact of SiC-based power devices on these converters is investigated. Reductions in heatsink size and device losses …

A Lock-In Amplifier For Fluorescent Light Detection, Osman Oguz

Masters Theses

An integrated on-chip lock-in amplifier has been developed for fluorescent light detection for biological applications. The system includes 2.1 mm x 2.1 mm tiny chip using a photodiode transimpedance amplifier topology for the pre-amp, followed by gain amplifier, demodulator and filtering stages. Synchronous demodulator or phase sensitive detector stage has two different architectures to demonstrate the difference between the results. The recommended transmitting light frequency is between 0.5 kHz to 5 kHz. We used 1 kHz frequency for the test.

Timing Jitter In Symmetric Load Ring Oscillators And The Estimation Of Aperture Uncertainty In A-D Converters, Venkatesh Srinivasan

Masters Theses

Timing jitter in clock signals presents a limitation to the performance of a variety of applications and systems. The criticality of the issue is discussed with the A-D converter as the backdrop. Timing errors in the sampling clock, the analog input signal and the aperture uncertainty of the A-D converter degrade the signal-to-noise ratio performance. In this thesis, a method to estimate the aperture uncertainty of the converter has been developed. The model accounts for the converter’s quantization noise and differential non-linearity errors and thereby improves the accuracy of the estimation. The technique was applied to a 10-Bit converter and …

Development Of A High-Efficiency, Low-Power Rf Power Amplifier For Use In A High-Temperature Environment, Stephen Terry

Masters Theses

This thesis presents a study of the design of a high efficiency, low power, RF power amplifier that can operate over an extended temperature range. The amplifier has been implemented as a hybrid circuit with the active device fabricated in a 0.5μm silicon-on- sapphire CMOS technology and passive components implemented off-chip. First a review of power amplifiers is given. Next design considerations for low power, high efficiency amplifiers are presented. Finally design details and measurement results from a low-power Class E amplifier are presented. When operated with an output power of 1 mW, the Class E amplifier achieves an efficiency …

Complementary Bodydriving - A Low-Voltage Analog Circuit Technique Realized In 0.35um Soi Process, Yong Leekee

Masters Theses

This thesis presents a study of several analog circuit primitives that utilize the body terminal as a signal port to achieve low-voltage operation and high performance. Several issues relating to low-voltage applications as well as the trends of technology scaling in the near future are presented. Principles of the body-driven transistor for both PMOS and NMOS in PDSOI technology are described, and critical design considerations are discussed. The design of low-voltage analog primitives (cascode current mirror and differential pair) are described and analyzed in detail. A discussion of the design and analysis of a 4-quadrant analog multiplier is also presented. …

Decomposition Of High-Order Fir Filters And Minimum-Phase Filter Design, Wei Su

Masters Theses

In this study, the implementation of high-order FIR filter decomposition and minimum-phase filter design is investigated. One method is presented for decomposing arbitrary linear-phase FIR filters with distinct roots into the cascade of first-order, second-order and fourth-order subfilters. The other method is described for transforming nonrecursive filters with even-order, equal-ripple attenuation in the pass-band, stop-band and linear-phase into those with minimum-phase and half the degree, and again with equal-ripple attenuation in the pass-band and stop-band. The technique consists of quick and accurate polynomial root finding of the z -domain filter transfer function by searching a finite region in the complex …

Implementing Neural Network-Based Face Detection Onto A Reconfigurable Computing System Using Champion, Bernadeta Srijanto

Masters Theses

From the innovation of the mechanical computers to the invention of semiconductors, there is Adaptive Computing System (ACS), which can be customized to suit users’ specific applications. Automated system software is needed to accommodate application mapping onto an ACS as it takes an extensive amount of time to perform the process manually. CHAMPION is an automatic mapping tool developed at the University of Tennessee. Using Khoros Cantata workspace as its input, CHAMPION’s goal is to improve designer productivity by 100 percent. The neural network section of face detection was one of multiple applications used as the challenge problem to CHAMPION. …

Hardware Implementation Of The Pet Backprojection Algorithm Using Fpga Technology, D. Eric Harrah

Masters Theses

Backprojection is used in the recovery of 2D and 3D images in positron emission tomography (PET). PET is used by medical personnel in the detection and location of growths or tumors that lie within the human body. Current image reconstruction using the Backprojection algorithm requires a great deal of processing time to complete. The general method used to decrease processing time is a multi-processor system with each processor working on a portion of the final image to be reconstructed. This thesis will focus on implementing the Backprojection algorithm utilizing a hardware platform. The Wildcard PCMCIA card, which contains a Virtex …

Study Of Non-Equilibrium Electron Dynamics In Metals, Wael Mohamed Gomaa Ibrahim

Electrical & Computer Engineering Theses & Dissertations

Thermal phenomena, such as heat propagation, lattice melting, and ablation, are the result of energy deposition in metals. A fundamental understanding of the electron dynamics leading to these thermal phenomena would benefit many laser applications, such as laser deposition of thin films and laser processing.

In this work, thin metal films were prepared using the resistive heating evaporation technique. High dynamic range autocorrelators were constructed to characterize the different laser systems used in this study. The nonequilibrium electron dynamics in single layer gold films, multi-layer gold-vanadium, and gold-titanium films were studied. The time evolution of the electron temperature was monitored …

Excimer Emission From Pulsed Microhollow Cathode Discharges, Mohamed Moselhy

Electrical & Computer Engineering Theses & Dissertations

Microhollow cathode discharges (MHCDs) are direct current, high-pressure, non-equilibrium gas discharges. Direct current MHCDs in xenon and argon have shown to emit excimer radiation at 172 and 127 nm, respectively. Internal efficiency of excimer emission in DC MHCD was measured to be 6–9% in xenon, and 1–6%, depending on the gas flow rate in argon. This high efficiency is due to the high rate of rare gas excitation by electrons accelerated in the cathode fall and to subsequent three-body collisions in the high-pressure gas. The excimer power scales linearly with current; however, due to the increasing size of the source …

Development Of An Efficient Ti:Sapphire Laser Transmitter For Atmospheric Ozone Lidar Measurements, Khaled A. Elsayed

Electrical & Computer Engineering Theses & Dissertations

The impetus of this work was to develop an all solid-state Ti:sapphire laser transmitter to replace the current dye lasers that could provide a potentially compact, robust, and highly reliable laser transmitter for differential absorption lidar measurements of atmospheric ozone. Two compact, high-energy pulsed, and injection-seeded Ti:sapphire lasers operating at a pulse repetition frequency of 30 Hz and wavelengths of 867 nm and 900 nm, with M² of 1.3, have been experimentally demonstrated and compared to model results. The Ti:sapphire lasers have shown the required output beam quality at maximum output pulse energy, 115 mJ at 867 nm and …

Airborne Radar Interference Suppression Using Adaptive Three-Dimensional Techniques, Todd B. Hale

Theses and Dissertations

This research advances adaptive interference suppression techniques for airborne radar, addressing the problem of target detection within severe interference environments characterized by high ground clutter levels, levels, noise jammer infiltration, and strong discrete interferers. Two-dimensional (2D) Space-Time Adaptive Processing (STAP) concepts are extended into three-dimensions (3D) by casting each major 2D STAP research area into a 3D framework. The work first develops an appropriate 3D data model with provisions for range ambiguous clutter returns. Adaptive 3D development begins with two factored approaches, 3D Factored Time-Space (3D-FTS) and Elevation-Joint Domain Localized (Elev-JDL). The 3D adaptive development continues with optimal techniques, i.e., …

Theory And Design Of Mixed Lumped-Distributed Cross-Coupled Filters With Applications To Linear Phase Shifter And Tunable Filters, Sanghoon Shin

Dissertations

Using cross-coupled networks of a new concept, transmission zeros were efficiently located in the complex frequency-domain. With this approach, the group delay and attenuation slope of the circuit network can be controlled to get both sharp rejection characteristics and linear phase slopes. In order to achieve this performance, various types of combline filters are suggested. Various simulation tools (commercial linear circuit and E-M simulators), as well as the developed pole-zero locator program, were used to design a new class of cross-coupled networks. In particular, the polezero locator program can be used to extract an equivalent circuit of the topology that …

Experimental Studies Of Wave Propagation In Three-Dimensional Photonic Crystals, John M. Tobias

Dissertations

Photonic crystals were proposed fifteen years ago. Propagation is selectively prevented through these crystals resulting in a photonic band gap, that is, a frequency region where light cannot propagate. These frequency bands are analogous to electronic band gaps in solid-state crystals.

The optical properties of the photonic crystal in regions near the band gap remain relatively unexplored. Yet, there is significant evidence to suggest that this avenue of investigation can provide useful optical and microwave applications. Numerical studies have predicted that the effective permittivity near the photonic band gap approaches zero and becomes negative. Selfcollimation of the propagating beam and …

Stereo Matching Algorithm By Propagation Of Correspondences And Stereo Vision Instrumentation, Peerajak Witoonchart

Theses

A new image processing method is described for measuring the 3-D coordinates of a complex, biological surface. One of the problems in stereo vision is known as the accuracy-precision tradeoff problem. This thesis proposes a new method that promises to solve this problem. To do so, two issues are addressed. First, stereo vision instrumentation methods are described. This instrumentation includes a camera system as well as camera calibration, rectification, matching and triangulation. Second, the approach employs an array of cameras that allow accurate computation of the depth map of a surface by propagation of correspondences through pair-wise camera views.

The …