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Binaural Sound Localization Using Neural Networks, Rushby C. Craig
Binaural Sound Localization Using Neural Networks, Rushby C. Craig
Theses and Dissertations
The purpose of this study was to investigate the use of Artificial Neural Networks to localize sound sources from simulated, human binaural signals. Only sound sources originating from a circle on the horizontal plane were considered. Experiments were performed to examine the ability of the networks to localize using three-different feature sets. The feature sets used were: time-samples of the signals, mena Fast Fourier Transform magnitude and cross correlation data, and auto-correlation and cross correlation data. The two different types of sound source signals considered were tones and gaussian noise. The feature set which yielded the best results in terms …
Robotic Tactile Sensors Fabricated From A Monolithic Silicon Integrated Circuit And A Piezoelectric Polyvinylidene Fluoride Thin Film, Craig S. Dyson
Robotic Tactile Sensors Fabricated From A Monolithic Silicon Integrated Circuit And A Piezoelectric Polyvinylidene Fluoride Thin Film, Craig S. Dyson
Theses and Dissertations
The purpose of this research effort was to design, fabricate, and test a tactile sensor system consisting of an external high impedance switch circuit, an external multiplexing circuit, and a tactile sensor IC. In order to accomplish this objective, a hardware design and selection process was implemented along with a logical test methodology. An external multiplexer circuit samples all of the array elements in 50 ms. The current prototype sensor has linearity spanning loads of 0.8 g to 135 g, a load resolution of 20 g, and a maximum bandwidth of 25 Hz. Using an elementary shape recognition algorithm the …
A Time-Dependent Adaptive Filter For Cochannel Interference Reduction, Matthew H. Foster
A Time-Dependent Adaptive Filter For Cochannel Interference Reduction, Matthew H. Foster
Theses and Dissertations
This thesis presents a Time Dependent Adaptive Filter (TDAF) which exploits the cyclostationarity of digitally modulated communications signals and seeks to improve the Signal to Interference Ratio (SIR) and Signal to Noise Ratio (SNR) of such signals. The TDAF is embedded in a computer simulation of a simple communication system consisting of a data source, data formatter, pulse shaping filter, BPSK modulator, and demodulator. In the simulation the TDAF and a Time Independent Adaptive Filter (TIAF) attempt to extract the Signal of Interest (SOI) from noise or interference. the criteria of Mean Squared Error (MSE) is used as the primary …
A Rigorous Uniform Diffraction Analysis Of The Electromagnetic Scattering From Impedance Edges And Junctions, Joseph C. Fortney
A Rigorous Uniform Diffraction Analysis Of The Electromagnetic Scattering From Impedance Edges And Junctions, Joseph C. Fortney
Theses and Dissertations
This paper investigates the scattering from impedance strips and impedance-loaded conducting strips. The impedance strips are analyzed using Senior's impedance half plane formulation. Once the primary diffraction from the impedance half plane is presented, it is used to develop multiple diffraction mechanisms on an impedance strip. The scattering from impedance-loaded strips are analyzed using Maliuzhinets' impedance wedge formulation. The primary diffraction mechanism from an impedance wedge is used to develop the multiple diffractions on an impedance double wedge. The multiple diffractions on both types of strips are developed using the Extended Spectral Ray Method. Sample calculations are made for impedance …
Wave Propagation In A Randomly Inhomogeneous Medium - A Study Of The Problem, Kyle Hunter
Wave Propagation In A Randomly Inhomogeneous Medium - A Study Of The Problem, Kyle Hunter
Theses and Dissertations
The problem of calculating the scintillation index of an atmospherically propagating spherical wave is examined. The fourth statistical moment of the complex field is obtained by using Feynman (path) integral techniques applied to the stochastic parabolic equation. The general trajectory of each Feynman integral is approximated by a truncated Fourier-sine series and the infinite-fold integration of the Feynman integral is reduced to a three-fold Riemann integral which is shown to match results derived under different assumptions. This thesis is highly tutorial.
A Robust Digital Flight Control System For An Unmanned Research Vehicle Using Discrete Quantitative Feedback Theory, Donald J. Lacey Jr.
A Robust Digital Flight Control System For An Unmanned Research Vehicle Using Discrete Quantitative Feedback Theory, Donald J. Lacey Jr.
Theses and Dissertations
This thesis describes application of digital multiple-input multiple- output (MIMO) Quantitative Feedback Theory (QFT) technique to the design of a three axis rate controller for the Lambda Unmanned Research Vehicle. The resulting robust controller performs well throughout the flight envelope without gain scheduling. It results from research done at the Air Force Institute of Technology. The Lambda URV was designed by the Control Systems Development Branch of the Wright Laboratory at Wright-Patterson AFB, OH for flight testing aircraft control hardware and software. The flight control system is built using a small perturbation linear model developed from flight test data. The …
An Investigation Of A Design For A Finite-Difference Time Domain (Fdtd) Hardware Accelerator, James R. Marek
An Investigation Of A Design For A Finite-Difference Time Domain (Fdtd) Hardware Accelerator, James R. Marek
Theses and Dissertations
This study investigated increasing the speed of Finite-Difference Time Domain (FDTD) cell calculations through a special purpose architecture using Very Large Scale Integration (VLSI). These FDTD cell equations model inhomogeneous, isotropic, lossy magnetic and dielectric materials. Special attention was given to simplicity and performance, using the fastest components generally available in AFIT VLSI programs, while attempting to minimize component count. A VHSIC Hardware Description Language simulation of the proposed chip established design feasibility and provided performance estimates: 350 ns to generate the first cell value, 200 ns thereafter (30 MFLOPS maximum double-precision). This study also implemented boundary conditions in hardware …
Analysis Of Visual Illusions Using Multiresolution Wavelet Decomposition Based Models, John S. Laing
Analysis Of Visual Illusions Using Multiresolution Wavelet Decomposition Based Models, John S. Laing
Theses and Dissertations
This thesis provides alternatives to the explanation that spatial filtering is responsible for the perception of illusory contours in the Kanisza Triangle illusion. Specifically, we use a Multiresolution Wavelet Decomposition to divide an image into spatial-frequency bands that are used as inputs to three biologically motivated models. The thesis includes a brief tutorial of Wavelet theory and an in-depth explanation of our implementation of recently published algorithms for Multiresolution Wavelet Analysis. The first model is based on the saccadic movements of the human eye. It demonstrates the importance of the high spatial-frequency content of an image in the formulation of …
Development Of High Angle Of Attack Control Laws For An Unstable, Non- Minimum Phase Aircraft Using Variations Of The Quantitative Feedback Technique, Mark A. Mcclure
Development Of High Angle Of Attack Control Laws For An Unstable, Non- Minimum Phase Aircraft Using Variations Of The Quantitative Feedback Technique, Mark A. Mcclure
Theses and Dissertations
This thesis discusses the application of variations of the quantitative feedback technique to a control problem with unstable, non-minimum phase plants. The X-29A research aircraft is used as the basis for developing a set of representative linearized aircraft dynamics models, which are modified to allow for the use of differential canard control inputs for enhanced maneuverability at extreme angles of attack. A specialized design approach is presented to develop frequency dependent weighting matrices, and the shortcomings of traditional methods are discussed. Four independent longitudinal compensators are developed by first designing loop transmission functions. Discussion is provided that addresses the limitations …
Design And Testing Of A Lightweight, Planar Microwave Lens, Paul M. Proudfoot
Design And Testing Of A Lightweight, Planar Microwave Lens, Paul M. Proudfoot
Theses and Dissertations
This thesis documents the design, fabrication, and testing of a lightweight, planar microwave lens. The lens consists of two planar arrays of lightweight printed circuit antennas interconnected by microstrip lines whose length varies as a function of position on the lens. Microwave energy is coupled from one face of the lens to the other by means of a slot etched in the ground plane. At 8.0 GHz the lens is ten wavelengths across, is less than 1/8 inch thick, and weighs less than 4 pounds. The lens can scan a beam over a ± 30 degree region in both the …
Design Of A Fiber Optic Image Transmission Link, Justin D. Redd
Design Of A Fiber Optic Image Transmission Link, Justin D. Redd
Theses and Dissertations
An original design is presented for a fiber optic based digital image transmission link operating at a serial bit rate of 250 Mbits/Second. The link is designed as an integral part of an airborne infrared imaging system with particular emphasis on avoiding problems associated with aircraft electromagnetic interference (EMI). Unique features include simplicity (single PC board transmitter and receiver), low power, low cost (under $3,000), and use of the latest off-the-shelf components (including the Gazelle GA9011/GA9012 HOT ROD chip set). Theoretical modeling is used to predict a bit error rate of better than 10-15, while actual measurements include …
Sensing Refractive Turbulence Profiles Using Wave Front Slope Measurements From Two Reference Sources, Michael D. Rejack
Sensing Refractive Turbulence Profiles Using Wave Front Slope Measurements From Two Reference Sources, Michael D. Rejack
Theses and Dissertations
This thesis examines a remote sensing technique for measuring the atmospheric structure constant as a function of altitude by performing spatial correlation or wavefront sensor measurements. Two point sources are used to irradiate two wavefront sensors in the aperture plane of an optical system. The geometric relationship between the sources and the sensors gives rise to crossed optical paths. At the point where the paths cross, the correlation value of the turbulence contributions will be at a peak. The correlation is shown to be mathematically related to the structure constant in terms of an integral of the structure constant multiplied …
Principal Base Parameter Analysis: Implementation And Analysis In An Adaptive Model-Based Robotic Controller, Gregory L. Showman
Principal Base Parameter Analysis: Implementation And Analysis In An Adaptive Model-Based Robotic Controller, Gregory L. Showman
Theses and Dissertations
Principal Base Parameter Analysis (PBPA) is a general and systematic procedure for determining the dynamic parameters that directly contribute to the joint torques of a manipulator, ranked in order of sensitivity. The feasibility of employing PBPA as an aid in the design and tuning of adaptive model-based controllers for industrial manipulators is rigorously investigated. This is accomplished by employing PBPA to determine the minimal size of the adaptive parameter vector and more importantly, to develop a less heuristic procedure for controller tuning. A simple, step-by-step procedure is developed wherein the manipulator torque equations are used in conjunction with PBPA to …
Infrared Target Recognition, Brian D. Singstock
Infrared Target Recognition, Brian D. Singstock
Theses and Dissertations
In this thesis, three approaches were used for Automatic Target Recognition (ATR). These approaches were shape, moment and Fourier generated features, Karhunen-Loeve transform (KLT) generated features and Discrete Cosine Transform (DCT) generated features. The KLT approach was modelled after the face recognition research by Suarez, AFIT, and Turk and Pentland, MIT. A KLT is taken of a reduced covariance matrix, composed all three classes of targets, and the resulting eigenimages are used to reconstruct the original images. The reconstruction coefficients for each original image are found by taking the dot product of the original image with each eigenimage. These reconstruction …
Image Segmentation Using Affine Wavelets, Steven E. Smiley
Image Segmentation Using Affine Wavelets, Steven E. Smiley
Theses and Dissertations
This thesis discusses the use of the multiresolution representation and Radial Basis Function (RBF) neural networks to segment both FLIR and SAR imagery. The multiresolution approximation coefficients are used as features into the RBF network which learns to distinguish between different cultural and natural regions or objects. The wavelets used are Mallat's spline wavelet and Daubechies' compactly supported wavelets. Additionally, this thesis provides an explanation of wavelets in a tutorial manner. It introduces wavelet theory and discusses two different approaches to generating the multiresolution or wavelet representation.
Verification And Validation Of The Simulated Radar Image (Srim) Code Radar Cross Section Predictions, Dale A. Stanley
Verification And Validation Of The Simulated Radar Image (Srim) Code Radar Cross Section Predictions, Dale A. Stanley
Theses and Dissertations
The objectives of this study were to verify and validate the Simulated Radar Image (SRIM) Code Version 4.0 monostatic radar cross section (RCS) predictions. SRIM, uses the theory of Physical Optics (PO) to predict backscatter for a user specified aspect angle. Target obscuration and multiple reflections are taken into account by sampling the target with ray tracing. The software verification and validation technique followed in this study entailed comparing the code predictions to closed from PO equations, other RCS prediction software packages, and measured data. The targets analyzed were a sphere, rectangular flat plate, circular flat plate, solid right circular …
Face Recognition With The Karhunen-Loeve Transform, Pedro F. Suarez
Face Recognition With The Karhunen-Loeve Transform, Pedro F. Suarez
Theses and Dissertations
The major goal of this research was to investigate machine recognition of faces. The approach taken to achieve this goal was to investigate the use of Karhunen-Loe've Transform (KLT) by implementing flexible and practical code. The KLT utilizes the eigenvectors of the covariance matrix as a basis set. Faces were projected onto the eigenvectors, called eigenfaces, and the resulting projection coefficients were used as features. Face recognition accuracies for the KLT coefficients were superior to Fourier based techniques. Additionally, this thesis demonstrated the image compression and reconstruction capabilities of the KLT. This theses also developed the use of the KLT …
Real Imagery As A Three Dimensional Display, Juan C. Echeverry
Real Imagery As A Three Dimensional Display, Juan C. Echeverry
Theses and Dissertations
This research effort implemented two 3-D display designs to assess their performance and effect on an observer's depth perception. Both 3-D displays produced real images for the observer to view. The first display setup combined a lens relay with a two concave mirror projector. The second display setup combined the two concave mirror projector with a diffuser. The lens relay/ two concave mirror projector combination was successful in imaging a source from the CRT to a point in space above the two mirror system. The problem was that the observer could not assess the image location by just looking at …
An Investigation Of The Application Of Artificial Neural Networks To Adaptive Optics Imaging Systems, Andrew H. Suzuki
An Investigation Of The Application Of Artificial Neural Networks To Adaptive Optics Imaging Systems, Andrew H. Suzuki
Theses and Dissertations
Recurrent and feedforward artificial neural networks are developed as wavefront reconstructors. The recurrent neural network studied is the Hopfield neural network and the feedforward neural network studied is the single layer perceptron artificial neural network. The recurrent artificial neural network input features are the wavefront sensor slope outputs and neighboring actuator feedback commands. The feedforward artificial neural network input features are just the wavefront sensor slope outputs. Both artificial neural networks use their inputs to calculate deformable mirror actuator commands. The effects of training are examined.
Performance Analysis Of The Speckle Holography Image Reconstruction Technique, Rudolf N. Vonniederhausern
Performance Analysis Of The Speckle Holography Image Reconstruction Technique, Rudolf N. Vonniederhausern
Theses and Dissertations
In speckle holography, short exposures frames along with wave front measurements allow post processing image reconstruction. With speckle holography the amplitude of high spatial frequencies is boosted to allow resolution out to the diffraction limit of the telescope. To provide system parameters for the wave front sensor design, a software analysis program has been developed that provides the system transfer function as a function of the number and size of sensor subapertures and sensor noise. Trends in the ratio of the atmospheric coherence diameter to wave front subaperture size and the effect on the system transfer function have been obtained. …
Optical Image Segmentation Using Wavelet Correlation, Steven D. Pinski
Optical Image Segmentation Using Wavelet Correlation, Steven D. Pinski
Theses and Dissertations
This research introduces an optical method of segmenting potential targets using wavelet analysis. Implementation of an optical Harr wavelet is fulfilled using a magneto-optic spatial light modulator (MOSLM). Two methods of controlling wavelet dilation are explored: (1) spatial filtering of a ternary modulated MOSLM; (2) a single aperture positioned in front of a binary modulated MOSLM. Segmentation is performed through Vander Lugt correlation of a binarized image with a binarized optical wavelet. Three different image binarization methods are investigated for use in the correlation scheme: (1) average pixel value over an entire scene; (2) localized 4 x 4 pixel average …
Low Temperature Photoluminescence Study Of Silicon-Germanium Alloy Superlattices, Maxwell M. Chi
Low Temperature Photoluminescence Study Of Silicon-Germanium Alloy Superlattices, Maxwell M. Chi
Theses and Dissertations
Low temperature photoluminescence studies were performed on nine silicon germanium alloy superlattice samples. The luminescence spectra showed sharp peaks in the 0.95 to 1.05 eV energy range, and a broad band located 0.05 to 0.12 eV below the alloy bandgap. The sharp peaks were identified as transitions associated with impurity bound excitons. The linewidth was about 10 times that in pure silicon; in addition, the peaks shifted to lower energy as the sample temperature was raised from 1.4 to 15 K. These features were attributed to effects of random distribution of atoms in the alloy. The broad band shifted to …
An Analysis Of One-Dimensional Models Of The Insulating And Conducting Priz, Joseph W. Cook Iii
An Analysis Of One-Dimensional Models Of The Insulating And Conducting Priz, Joseph W. Cook Iii
Theses and Dissertations
This study attempted to analytically reproduce experimental and analytical data, on the single-insulated and conducting PRIZ, presented in 1987 and 1988 by the Soviet scientists Bliznetsov et al. Our onedimensional analytical models, derived from earlier Soviet reports, have consistently reproduced previously reported data on the PRIZ. In this study, the same codes were successfully used to analyze the effects of injection at high and low intensity exposures (30 µW/cm2 to 500 mW/cm2) Although the codes qualitatively duplicated the nature of the space charge distribution in the single-insulated and conducting PRIZ, our quantitative results were significantly different from …
Self-Pumped Phase-Conjugate Twyman-Green Interferometry Using A Batio3 Crystal, Deborah A. Determan
Self-Pumped Phase-Conjugate Twyman-Green Interferometry Using A Batio3 Crystal, Deborah A. Determan
Theses and Dissertations
The Air Force uses optical imaging systems in many fields such as communications, target recognition, and missile guidance. For proper execution of these applications, the optical imaging systems use in these fields must be of extremely high quality so that an ideal image is obtained. In divergent beam configurations, this type of interferometer would eliminate the need for high quality reference optics needed in conventional Twyman-Green interferometry. The objective of this thesis is to demonstrate phase conjugate Twyman-Green interferometry using a barium titanate (BaTiO3) crystal as the phase conjugating mirror in the reference arm of the interferometer and …
Photoluminescence Spectroscopy Of Mbe Grown Gallium Antimonide, John A. Dorian
Photoluminescence Spectroscopy Of Mbe Grown Gallium Antimonide, John A. Dorian
Theses and Dissertations
Experimental data are presented for the energy levels of the native acceptor and bound exciton emissions of GaSb grown by MBE and studied with low temperature photoluminescence (PL) spectroscopy. The undoped GaSb emissions showed a donor-acceptor pair transition with an observed emission peak at 776 meV, a peak at 716 meV usually associated with the ionization level of the acceptor, and bound exciton transitions in the energy range from 796 to 804 meV. Other unidentified peaks were observed at about 805 meV. Temperature and power dependence studies of the acceptor peak confirmed donor-acceptor pair (DAP) behavior. A GaSb sample grown …
Vibrational Energy Transfer In Bromine Monofluoride, Tim L. Thompson
Vibrational Energy Transfer In Bromine Monofluoride, Tim L. Thompson
Theses and Dissertations
Bromine monofluoride (BrF), an interhalogen molecule, is a prospective chemical laser candidate. This study continues research begun in characterizing radiative and collisional dynamics in BrF. Vibrational energy transfer of BrF is studied using time resolved laser induced fluorescence (LIF) techniques and observing the spectrally resolved emission. First, vibrational transfer induced by the BrF production mix is determined to follow the Montroll- Shuler model and Landau-Teller scaling with a fundamental rate coefficient of kv(1,0) = (4.0) x 10-12 cm3/(molecules seconds). Also, rate coefficients for the rare gases were found to scale with the reduced mass of the collision …
An Analysis Of Tracking And Impact Predictions, Susanne V. Lefebvre
An Analysis Of Tracking And Impact Predictions, Susanne V. Lefebvre
Theses and Dissertations
The accuracy of the United States Space Command's early Tracking and Impact Predictions and its OPREP-3 report initiation procedure are analyzed. The study involves satellites which decayed between 1987 and 1990. Each of the early decay predictions are compared to the final prediction with the resulting time error compared to the accuracy level asserted by the Space Surveillance Center. The results of this study indicate that the accuracy of the decay predictions is usually, but not always, within the asserted accuracy level. The results also suggest the existence of a positive bias indicating that the early decay predictions are routinely …
A Topographical Analysis Of The Human Electroencephalogram For Patterns In The Development Of Motion Sickness, George S. Vogen
A Topographical Analysis Of The Human Electroencephalogram For Patterns In The Development Of Motion Sickness, George S. Vogen
Theses and Dissertations
A topographical analysis was performed on 12 electroencephalograms (EEGs) collected from 10 volunteers who experienced motion sickness through cross-coupled Coriolis stimulation. Seven males and three females participated in the research conducted at the Air Force Institute of Technology, Wright- Patterson AFB. Two male volunteers participated in double-blind placebo/ phenytoin trials. Static brain maps and dynamic EEGs which focused on delta (below 3Hz) activity during the development of motion sickness revealed a seizure-like propagation pattern. With initial symptoms, a clear left parietal focus was seen in all records. A less dominant left fronto-temporal focus was present in 11 of the 12 …
Radar System Classification Using Neural Networks, David M. Cameron
Radar System Classification Using Neural Networks, David M. Cameron
Theses and Dissertations
This study investigated methods of improving the accuracy of neural networks in the classification of large numbers of classes. A literature search revealed that neural networks have been successful in the radar classification problem, and that many complex problems have been solved using systems of multiple neural networks. The experiments conducted were based on 32 classes of radar system data. The neural networks were modelled using a program called the Neural Graphics Analysis System. It was found that the accuracy of the individual neural networks could be increased by controlling the number of hidden nodes, the relative numbers of training …
Verification And Validation Of The Comprehensive Operational Support Evaluation Model For Space, Lawrence A. Cooper
Verification And Validation Of The Comprehensive Operational Support Evaluation Model For Space, Lawrence A. Cooper
Theses and Dissertations
This study details the verification and validation (V and V) of the Comprehensive Operational Support Evaluation Model for Space (COSEMS). COSEMS is an Ada-based simulation which models spacecraft constellation support concepts such as support from the ground and on-orbit support. While the model is intended for use in analyzing Strategic Defense System concepts, it can easily evaluate non-military satellite constellations. The V&V was confined to a subset of the over 200 subprograms which comprise COSEMS. This subset covered random number generation, reliability, orbital mechanics, and mission planning functions. The study used traces and comparison to other models to perform the …