Engineering Commons^™

Radar Cross Section Models For Limited Aspect Angle Windows, Mark C. Robinson

Theses and Dissertations

This thesis presents a method for building Radar Cross Section (RCS) models of aircraft based on static data taken from limited aspect angle windows. These models statistically characterize static RCS. This is done to show that a limited number of samples can be used to effectively characterize static aircraft RCS. The optimum models are determined by performing both a Kolmogorov and a Chi-Square goodness-of-fit test comparing the static RCS data with a variety of probability density functions (pdf) that are known to be effective at approximating the static RCS of aircraft. The optimum parameter estimator is also determined by the …

Digital Signal Processing Using Lapped Transforms With Variable Parameter Windows And Orthonormal Bases, Brian D. Raduenz

Theses and Dissertations

This thesis develops and evaluates a number of new concepts and tools for the analysis of signals using variable overlapped windows and orthonormal bases. Windowing, often employed as a spectral estimation technique, can result in irreparable distortions in the transformed signal. By placing conditions on the window and incorporating it into the orthonormal representation, any signal distortion resulting from the transformation can be eliminated or cancelled in reconstruction. This concept is critical to the theory underpinning this thesis. As part of this evaluation, a tensor product based general N-point fast Fourier transform algorithm was implemented in the DOD standard language, …

Automated Face Recognition System, Kenneth R. Runyon

Theses and Dissertations

In this thesis three variations of an end-to-end face recognition prototype system are developed, implemented and tested. Each version includes real-time image collection, automated segmentation, preprocessing, feature extraction, and classification. The first version uses a Karhunen Loeve Transform (KLT) feature extractor and a K-nearest neighbor classifier. Version two uses the same feature set but utilizes a multilayer perception neural network with a back propagation learning rule. Finally the third version uses a Discrete Cosine Transform as the feature extractor and the K-nearest neighbor as the classifier. Only the KLT versions of the system were tested. The tests were based on …

Acquisition Of Direct Sequence Spread Spectrum Signals Using Digital Signal Processing Techniques, Ronald E. Schmitz

Theses and Dissertations

This thesis investigates the use of digital signal processing (DSP) techniques to achieve initial synchronization with Global Positioning System (GPS) Pseudo-Noise (PN) signals. Synchronization with the transmitted PN signal is essential to the despreading of the transmitted Direct Sequence Spread Spectrum (DS/SS) signals and decoding of the transmitted satellite data. The use of DSP methods to decrease the time required to achieve initial synchronization is investigated. This thesis proposes an initial acquisition section of the GPS receiver and derives the equations to show the method is mathematically feasible. Computer simulations of the proposed receiver using received signals corrupted by Doppler …

Signal Approximation With A Wavelet Neural Network, Charles M. Westphal

Theses and Dissertations

This study investigated the use of Wavelet Neural Networks (WNN) for signal approximation. The particular wavelet function used in this analysis consisted of a summation of sigmoidal functions (a sigmoidal wavelet). The sigmoidal wavelet has the advantage of being easily implemented in hardware via specialized electronic devices like the Intel Electronically Trainable Analog Neural Network (ETANN) chip. The WNN representation allows the determination of the number of hidden-layer nodes required to achieve a desired level of approximation accuracy. Results show that a bandlimited signal can be accurately approximated with a WNN trained with irregularly sampled data. Signal approximation, Wavelet neural …

Optical Haar Wavelet Transforms Using Computer Generated Holography, Peter G. Block

Theses and Dissertations

This research introduces an optical implementation of the continuous wavelet transform to filter images. The wavelet transform is modeled as a correlation process and is implemented with a Vander Lugt correlator. The orthonormal basis set used is composed of two one-dimensional Haar functions and a two-dimensional Haar function. Each wavelet, as well as its first two dyadic scalings, is implemented with computer generated holography. The Interferogram method, which represents a function only in terms of its phase, is used to encode the wavelet functions. The results are imaged onto a CCD array and captured using a framegrabber. The optical results …

Real Image Visual Display System, James R. Brandt

Theses and Dissertations

This thesis investigates a technique for improving the perception of three-dimensionality in images generated by a Silicon Graphics workstation. The technique involves using a spherical mirror into which the graphics from the CRT are projected. A real image of the graphic is formed by the mirror and it appears to be floating at the image plane. The three-dimensional effect is improved by adding reflections or shadows of the displayed object. Additionally, a method of using real objects with computer generated shadows and computer generated objects with real shadows is investigated. This is done in an effort to quantify how far …

Object Tracking Through Adaptive Correlation, Dennis A. Montera

Theses and Dissertations

This paper discusses the use of a correlation based system to track, an object through a series of images based on templates derived from previous image frames. The ability to track is extended to sequences which include multiple objects of interest within the field of view. This is accomplishes by comparing the height and shape of the template autocorrelation to the peaks in the correlation of the template with the next scene. The result is to identify the region in the next scene which best matches the designated target. In addition to correlation plane postprocessing, an adaptive window is used …

Stabilization Of Passively Mode-Locked Semiconductor Laser Repetition Frequency, Roger Helkey, Dennis J. Derickson, Alan Mar, John Wasserbauer, Robert L. Thornton

Electrical Engineering

No abstract provided.

Nsf Sponsored Innovation In Engineering And Cornputer Science, Jacob Abel, Patricia Daniels, James G. Harris, Harry Hedges

Electrical Engineering

No abstract provided.

Model For The Infrastructure Of Engineering Education, James G. Harris, Karen Frair, Win Aung, Susan T. Hill

Electrical Engineering

There are many ways to describe and model physical systems. The infrastructure of engineering education in the United States is an example of such a system, and it is the intent of this report to describe and model this infratructure. The means for doing this starts with the graduation statistics for the year 1989 given by the Computer Aided Science Policy Analysis & Research Database System (CASPAR) developed for the National Science Foundation by Quantum Research Corporation [1], and uses a simple categorization for the institutions that contribute to those statistics. This categorization sorts the post -secondary institutions in the …

Fabrication And Characterization Of Gated Silicon Field Emission Micro Triodes, Nanchou Liu

Dissertations

This dissertation describes the fabrication technology and characterization of a gated silicon field emission micro triode that is a novel electron tunneling device for generating electron emission into a vacuum. Conic (point) and wedge field emitter structures with nm-scale radii were fabricated in silicon and GaAs by etching, MOCVD and dry oxidation. A new self-aligned process was developed for fabrication of vertical field emission triodes. This process allows control of gate opening to less than 0.5 μm diameter without the need of electron-beam writing. It also provides a planar gate electrode and a thick dielectric layer for reduction of the …

Adaptive Map Configuration And Dynamic Routing To Optimize The Performance Of A Satellite Communication Network, Santhalingam Balasekar

Theses

Availability of alternate routes are shown to enhance the performance of non-hierarchical circuit switched networks at moderate load conditions on which the networks typically operate. But alternate routes introduce instability at heavy and overloaded conditions and at these load conditions the network performance is found to deteriorate. To alleviate this problem, one of the control mechanism used is to reserve a fraction of the capacity of each link for direct routed calls. In this work, the feasibility of changing the facilities of a satellite network is taken advantage in optimizing the performance of such a network. A mesh connected, circuit …

Point Pattern Matching By Heuristic Methods : A Genetic Algorithm And Simulated Annealing, Erh-Chin Chen

Theses

The problem we consider is to find a subset of points in a pattern that best match to a subset of points in another pattern through a transformation in an optimal sense. Exhaustive search to find the best assignment mapping one set of points to another set is, if the number of points that are to be matched is large, computationally expensive. We propose two stochastic searching techniques - a genetic algorithm and simulated annealing to search for the best ("almost the best") assignment efficiently. To make the comparison between GA and SA fair, we introduce a piece-wise linear cooling …

An Information Theoretic Approach To Dsn Evaluation, Vivek Mehrotra

Theses

Evaluation of Distributed Sensor Networks (DSN's) for optimal detection using Bayesian cost formulation methods has been the objective of several studies. There have been a few studies on DSN evaluation using an information theoretic approach, wherein an assymetric channel models a detector. We look at the multi-sensor system at the receiver as a black-box and model it as an assymetric channel whose cross over probabilities depend on the probabilties of detection and of false alarm. These probabilities in turn depend on the thresholds of the local detectors and on the fusion rule used. We consider the case wherein the receiver …

Bragg Reflection Grating Waveguide, Wei Zhong

Theses

Bragg reflection waveguides (BRW) are non-conventional optical guides in which optical confinement is achieved via periodic set of grooves or stratified media along the guiding path. BRW may also serve as optical filters, because of spectral discrimination of the guiding process. A novel UV laser ablation technique was used in this thesis to fabricate periodic metal-clad polymeric waveguides. Spin-on technique was applied to fabricate the waveguide core on glass substrates, evaporation of metal film and selective ablation process defined the optical guides. Various periodicities have been fabricated and the near field patterns have been measured to compare the different guiding …

Photoluminescence And Raman Studies Of Cds Films Grown By Metal-Organic Chemical Vapor Deposition On Si{111} Substrates, Alok K. Berry, P. M. Amirtharaj, Jing Tong Du, Jack L. Boone, Don D. Martin

Electrical and Computer Engineering Faculty Research & Creative Works

CdS epitaxial films grown using metal-organic chemical vapor deposition on Si{111} substrates at growth temperatures ranging from 270 to 325 °C have been characterized using photoluminescence and Raman spectroscopy. Out of all the samples the best optical behavior is obtained from that grown at the lowest temperature. Samples grown at the lowest temperature exhibited increased intensity of the bound excitonic peaks and reduced emission at the defect-related luminescence region. The Raman spectra were compatible with the film surface being normal to the c axis, indicating a preferred growth orientation. © 1992.

A Gaze-Addressing Communication System Using Artificial Neural Networks, Gabriel Baud-Bovy

Dissertations and Theses

Severe motor disabilities can render a person almost completely incapable of communication. Nevertheless, in many cases, the sensory systems are intact and the eye movements are still under good control. In these cases, one can use a device such as the Brain Response Interface (BRI) to command a remote control (e.g. room temperature, bed position), a word-processor, a speech synthesizer, and so on.

The BRI is a gaze-addressing communication system that was developed by Dr. Erik E. Sutter at the Smith-Kettlewell Eye Research Institute, San-Francisco: a menu of communication objects (e.g. letter, word, command) is displayed on a TV screen; …

Short Pulse Generation Using Multisegment Mode-Locked Semiconductor Lasers, Dennis J. Derickson, R. J. Helkey, A. Mar, Judy R. Karin, J. G. Wasserbauer, J. E. Bowers

Electrical Engineering

No abstract provided.

Waste-Surface Mapping Of The Fernald K-65 Silos Using A Structured Light Measurement System, B. L. Burks, Fred W. Depiero, M. A. Dinkins, J. C. Rowe, C. B. Selleck, D. L. Jacoboski

Electrical Engineering

During FY 1991, a remotely operated surface-mapping measurement system was developed by the Robotics & Process Systems Division at Oak Ridge National Laboratory for use in the K-65 waste-storage silos at Fernald, Ohio. The mapping system used three infrared line-generating laser diodes as illumination sources and three high-resolution, low-lux, calibrated, black-and-white, chargecoupled- device video cameras as receivers. These components were combined to form structured light source range and direction sensors with six different possible emitter-receiver pairs. A technology demonstration and predeployment tests were performed at Fernald during July and August 1991, using the empty Silo 4 into which was placed …

Conservative Confidence Intervals Of Importance Sampling Estimates, Kurt Louis Kosbar, T. F. Chang

Electrical and Computer Engineering Faculty Research & Creative Works

Confidence intervals (CI) are used to gauge the accuracy of bit error rate (BER) estimates produced by Monte Carlo (MC) simulations. This work attempts to objectively evaluate the performance of Important Sampling (IS) simulations by applying the same statistical analysis tool. While it is not possible to evaluate the minimum size CI for arbitrary IS estimates, it is possible to over-bound the interval using a technique called conservative confidence interval (CCI) estimation. This bounding procedure is applied to a simple IS biasing technique. While the IS estimate may be superior to the MC estimate, the CCI fails to support this …

Interval Estimation And Monte Carlo Simulation Of Digital Communication Systems, Kurt Louis Kosbar, T. F. Chang

Electrical and Computer Engineering Faculty Research & Creative Works

This work quantifies the accuracy of bit error rate (BER) estimates produced by Monte Carlo simulations by carefully applying confidence interval estimation techniques. Due to numerical difficulties, some previous work in this area has assumed that the BER statistic possessed a Gaussian distribution. This work demonstrates that in some important regions the estimate is decidedly non-Gaussian, and application of central limit theorem arguments can result in errors in excess of an order of magnitude. This work investigates the accuracy of common approximations and the feasibility of exact calculation of confidence intervals, and presents a novel polynomial class approximation. By combining …

Object-Oriented Modeling Of Communication Systems, Kurt Louis Kosbar, Kevin W. Schneider

Electrical and Computer Engineering Faculty Research & Creative Works

Conventional communication system simulation programs and packages are written using procedural programming languages. Newly developed, object-oriented languages offer the simulation designer significantly different options and structures. By exploiting these new techniques it is possible to significantly increase the flexibility and extensibility of the simulation package. This allows the system analyst to efficiently re-use complex simulation code and quickly and reliably reconfigure the simulation. In addition, a single object-oriented simulation can be used in all stages of the design process, from conceptual design through fabrication and testing. A final benefit of the object-oriented techniques is that the simulation code closely matches …

Interaction Of Profiled Light With Contrapropagating Acoustic Waves: Fourier Transform Approach, Partha P. Banerjee, Chen-Wen Tarn, Jaw-Jueh Liu

Electrical and Computer Engineering Faculty Publications

A straightforward Fourier-transform approach is employed to investigate acousto-optic interaction between an input optical beam with arbitrary profile and contrapropagating cw sound in the Bragg regime. The process can be analyzed in terms of the simultaneous scattering of light by the two sound waves in the interaction region. Analytic expressions for the equivalent transfer functions are obtained and the scattered light profiles are plotted.

The Effect Of Contacts On The Performance Of Electron-Beam Controlled Gaas And Diamond Switches, Michael Kevin Kennedy

Electrical & Computer Engineering Theses & Dissertations

The performance of GaAs and diamond as electron-beam controlled closing and opening switches has been studied. An emphasis has been placed on the effect of contacts on the current-voltage characteristics. The two materials studied were GaAs and diamond. Using the same semi-insulating GaAs wafer as a source of material, a bulk device and a p-i-n device have been fabricated and compared. The asymmetry of the pin diode allows operation at higher voltage because of the ability to suppress the lock-on effect. Whereas GaAs was ionized through cathodoluminescence; diamond, in the form of thin films, has been directly ionized by the …

Design And Implementation Of Fuzzy Logic Controllers, Osama A. Abihana

Electrical & Computer Engineering Theses & Dissertations

The main objectives of our research are to present a self-contained overview of fuzzy sets and fuzzy logic, develop a methodology for control system design using fuzzy logic controllers, and to design and implement a fuzzy logic controller for a real system. In this thesis we first present the fundamental concepts of fuzzy sets and fuzzy logic. Fuzzy sets and basic fuzzy operations are defined. In addition, for control systems, it is important to understand the concepts of linguistic variables, linguistic values, term sets, fuzzy rule base, inference methods, and defuzzification methods. Second, we introduce a four-step fuzzy logic control …

Repetition Frequency Stabilisation Of Passively Mode-Locked Semiconductor Lasers, R. J. Helkey, Dennis J. Derickson, A. Mar, J. G. Wasserbauer, J. E. Bowers, R. L. Thornton

Electrical Engineering

The repetition frequency of an external cavity mode-locked GaAs semiconductor diode laser has been stabilized by voltage controlled electrical feedback. The phase noise has been reduced by 40dB at 1 kHz offset from the carrier and timing jitter reduced from more than 30ps to 4ps. This technique can be used to stabilize millimetre-wave mode-locked lasers.

Mode-Locking Of High-Power Resonant-Optical-Waveguide Diode Laser Arrays, Alan Mar, Dennis J. Derickson, Roger Helkey, John Bowers, Dan Botez

Electrical Engineering

We report the first mode-locked operation of a resonant optical waveguide (ROW semiconductor laser array. Pulsewidths as short as 23 ps and peak powers of over 1W are generated in a single-lobed beam.

Supercomputer-Based Spherical Scene Projector, Harold K. Brown, John G. Madry, Rufus H. Cofer, Samuel Peter Kozaitis

Electrical Engineering and Computer Science Faculty Publications

A multi-technology high performance computing system based on the Open Parallel Architecture Design Specification (OPADS) platform is being evaluated for use as a graphics engine for spherical scene projection. This system is designed to make available the massive quantities of real-time processing power needed to support complete real time scene generation and projection of complex dynamical maneuvers for applications such as scientific visualization and three dimensional database creation and interaction. A comparison is also provided between head mounted projection systems and walk-in spherical scene projection systems.

Bayesian Defeat Of Camouflage, Rufus H. Cofer

Electrical Engineering and Computer Science Faculty Publications

A new technique is shown for refining and reducing incoming camouflage data based upon the Bayesian paradigm. Innovation is displayed in use of a statistical conditioning sequence that avoids the need to form target features from the data. The result is a simplified and more accurate probabilistic indication of actual target presence. This probabilistic indication can then be incorporated into a variety of target detection scenarios or, alternately, to form the basis of a theoretically optimal Bayesian target detector. Numeric simulation is presented to show the effectiveness of the technique against simulated camouflage