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Computer Generated Holography As A Three-Dimensional Display Medium, Bryant L. Stuart
Computer Generated Holography As A Three-Dimensional Display Medium, Bryant L. Stuart
Theses and Dissertations
A process was developed to produce three dimensional images using computer generated holography (CGH). This process consisted of a series of steps that began with a geometric description of an object and concluded with a three dimensional holographic image being computed from a synthetic wavefront. The objects used in this series of steps (or CGH pipeline) were described geometrically as a collection of three dimensional points. The modular nature of the CGH pipeline provided a flexible platform from which to evaluate various object geometries, interference calculations algorithms, and interference pattern recording and reduction techniques. This system was implemented with general …
An Empirical Study Of Combining Communicating Processes In A Parallel Discrete Event Simulation, Ann K. Lee
An Empirical Study Of Combining Communicating Processes In A Parallel Discrete Event Simulation, Ann K. Lee
Theses and Dissertations
The primary goal of distributed discrete event simulations is to achieve speedup in simulation execution time by distributing the processing of the simulation over multiple processors. When partitioned for distribution in this fashion, simulations are typically partitioned such that there are more processes than processors. This thesis reviews existing methods for distributed discrete event simulations, and proposes general guidelines for efficient partitioning for a given communications topology based on empirical evidence. A performance analysis is conducted for two approaches to partitioning the system. The first method chosen is a mapping of multiple processes to a processor and the second approach …
Speech Coding And Compression Using Wavelets And Lateral Inhibitory Networks, Richard Ricart
Speech Coding And Compression Using Wavelets And Lateral Inhibitory Networks, Richard Ricart
Theses and Dissertations
The purpose of this thesis is to introduce the concept of lateral inhibition as a generalized technique for compressing time/frequency representations of electromagnetic and acoustical signals, particularly speech. This requires at least a rudimentary treatment of the theory of frames-which generalizes most commonly known time/frequency distributions--the biology of hearing, and digital signal processing. As such, this material, along with the interrelationships of the disparate subjects, is presented in a tutorial style. This may leave the mathematician longing for more rigor, the neurophysiological psychologist longing for more substantive support of the hypotheses presented, and the engineer longing for a reprieve from …
Measuring The Effectiveness Of Space: Satellite Weather Systems, Steven T. Wilson
Measuring The Effectiveness Of Space: Satellite Weather Systems, Steven T. Wilson
Theses and Dissertations
Using concepts from multivariate utility theory, basic orbital mechanics, and information regarding operational and planned meteorological satellites, this thesis develops a meaningful MOE to support high-level decision making regarding the allocation, acquisition, and operational deployment of space meteorological satellite (METSAT) assets. Satellite meteorological systems were chosen because of the ready availability of pertinent unclassified data. However, the methodology presented may be applied to any type of space system.
Analysis Of Hypersonic Blunt-Body Flows Using A Total Variation Diminishing Scheme And The Maccormack Scheme, Montgomery C. Hughson
Analysis Of Hypersonic Blunt-Body Flows Using A Total Variation Diminishing Scheme And The Maccormack Scheme, Montgomery C. Hughson
Theses and Dissertations
An explicit second-order accurate, total variation diminishing (TVD) scheme and the MacCormack scheme are applied to the Euler equations in axisymmetric form to study hypersonic blunt body flows. The modified flux approach of Harten, with modification by Yee, for two-dimensional flows is extended to treat axisymmetric flows. Calculated flow properties for the steady state, blunt body problem such as shock standoff distance, bow shock shape, surface pressure distribution and entropy jump conditions are compared to theory, results from the MacCormack scheme, and experimental data for Mach numbers of 3.0, 4.03, 5.06, 6.03 and 8.1. Additionally, the TVD and MacCormack schemes …
Real-Time Flight Simulation And The Head-Mounted Display - An Inexpensive Approach To Military Pilot Training, Philip A. Platt
Real-Time Flight Simulation And The Head-Mounted Display - An Inexpensive Approach To Military Pilot Training, Philip A. Platt
Theses and Dissertations
The integration of the low-cost head-mounted display (HMD), an inexpensive graphics workstation-based flight simulator, and a communications network was investigated to determine if the prototype of an inexpensive multi- aircraft Virtual Flight Simulator could be built. Previous research efforts have coupled HMD technology and flight simulation; however, the cost of these systems has been high. This thesis effort emphasized the use of joystick devices to emulate pilot control, the implementation of a fully enclosed virtual flight simulator, and the utilization of low-cost NTSC-based television technology to produce a prototype. The virtual flight simulator also contained a basic set of instruments …
Feasibility Analysis Of Developing A Formal Performance Model Of Ada Tasking, Kathryn J. Edwards
Feasibility Analysis Of Developing A Formal Performance Model Of Ada Tasking, Kathryn J. Edwards
Theses and Dissertations
As software system requirements become more complex, software engineers must carefully design the systems to ensure the systems to ensure the systems adequately meet all requirements, both functional and non-functional. Because real-time systems have timing constraints, in addition to the more traditional behavioral constraints, a comprehensive software design analysis model is required which incorporate performance, timing, and behavioral constraints. Although the Ada language tasking constructs are compiler independent, Ada tasking is dependent on its runtime environment; therefore, a formal model of Ada tasking and its associated runtime environment is important in order for system designers to make realistic decisions when …
Digital Control Of The Utah/Mit Dexterous Hand: Initial Evaluation And Analysis, Lloyd W. Rainey Iii
Digital Control Of The Utah/Mit Dexterous Hand: Initial Evaluation And Analysis, Lloyd W. Rainey Iii
Theses and Dissertations
An experimental digital platform is developed as an environment on which to evaluate digital control strategies for dexterous manipulation with a pneumatically actuated tendon-driven manipulator. This environment is used to begin the study of advanced control methods that are suitable for providing the tracking accuracy required for grasping and dexterous manipulation with a pneumatically actuated tendon-driven end-effector. The digital platform consists of a PC/AT-386 and a single board MC68020 microcomputer in a VME chassis with shared RAM between the two processors to control the Utah/MIT Dexterous Hand (UMDH). The MC68020 controls the A/D and D/A access for the UMDH, while …
A Biologically-Inspired Neural Network Architecture For Image Processing, Laurence E. Lazofson
A Biologically-Inspired Neural Network Architecture For Image Processing, Laurence E. Lazofson
Theses and Dissertations
This thesis project included a literature survey of biological and artificial neural network research followed by development and testing of high- order and image recognition hierarchical neural network algorithms. Following training, performance testing of second-order and third-order networks yielded maximum accuracies comparable to those achieved by multilayer perceptron classifiers operating on test data sets. Several versions of an image classification algorithm were tested for learning performance using pixel data from forward-looking infrared (FLIR) images of tanks, trucks, target boards, and clutter. Employing the biologically-motivated Lambertization and contrast normalization of pixel windows, correlations with multiple Gabor function wavelets, and a 'phase …
A Correlation And Forecasting Analysis On Lost Satellites, Kenneth R. Norton
A Correlation And Forecasting Analysis On Lost Satellites, Kenneth R. Norton
Theses and Dissertations
The relationship between the size of the United States Air Force Space Command's lost satellite lists and thirteen other variables is investigated. The thirteen variables contain the Space Surveillance Center crew's effort to work the lost list, solar activity, geomagnetic field strength, and the number of observations received each day from seven space track sensors. To identify the relationship of cause and effect between the lost lists and the thirteen variables, simple and multiple linear regressions are used on a data set that begins on 1 January 1988 and ends on 31 December 1988. Multiple linear regression and basic time-series …
An Evaluation Of The Educational Background And Knowledge Base Of Air Force Information Management Officers, Summer E. Scott
An Evaluation Of The Educational Background And Knowledge Base Of Air Force Information Management Officers, Summer E. Scott
Theses and Dissertations
This study compares the educational background and knowledge base recommended for Information Management professionals to that currently possessed by Air Force Information Management (IM) officers. The literature review revealed that information managers should have an educational background that provides them with knowledge in the areas of people, computers, systems, models, organization, and society. Statistics made available through the Air Force Manpower and Personnel Center (AFMPC) indicated that only 2.1% of all 70XX officers have a complete information resource management background, and only 7% have a technical or computer-related background.
Characterization Of Barium Titanate As An Optical Amplifier, George A. Vogel
Characterization Of Barium Titanate As An Optical Amplifier, George A. Vogel
Theses and Dissertations
The introduction of two-beam coupling in photorefractive materials has resulted in an extensive amount of research into their use as optical processing/computing elements. This dissertation develops the theoretical equations for two-beam coupling in barium titanate as an optical amplifier. One of the factors which limits the optical gain in photorefractive crystals is the loss of pump beam power to the amplification of parasitic light (beam fanning). This parasitic light is produced by light scattered from the pump beam by imperfections on both the crystal face and within the crystal. Through the analysis of signal and noise amplification as functions of …
Implementation Of The Modified Monte Carlo Technique Using Importance Sampling On The Block Oriented System Simulator, John B. Bennett
Implementation Of The Modified Monte Carlo Technique Using Importance Sampling On The Block Oriented System Simulator, John B. Bennett
Theses and Dissertations
The purpose of this thesis was to implement the Modified Monte Carlo technique using Importance Sampling on the Block Oriented System Simulator (BOSS). Computer simulation techniques of communications systems were reviewed. Next, conventional Monte Carlo techniques and Modified Monte Carlo techniques using Importance Sampling were reviewed. Models of Binary Phase Shift Keying (BPSK) systems using both Monte Carlo techniques were implemented and simulated. Reasons for the model using Importance Sampling not working correctly are postulated. The Monte Carlo technique is a method of ensuring the an inherently infinite procedure, such as determining system bit error rate (BER), can be determined …
Model-Based 3-D Recognition System Using Gabor Features And Neural Networks, Phung D. Le
Model-Based 3-D Recognition System Using Gabor Features And Neural Networks, Phung D. Le
Theses and Dissertations
A different approach to pattern recognition was attempted using Gabor features, artificial neural nets, and an image generator. The Gabor features and artificial neural nets are sound biological-based, and the image generator provides complete access to any view of an object. This thesis tested the idea that their integration could form a robust 3-D recognition system. The results of the research showed that the Gabor features together with a neural net were used successfully in classifying objects regardless of their positions, out-of- plane rotations, and to a lesser extent in-plane rotations. The Gabor features were obtained by correlating the image …
An Evolution Operator Solution For A Nonlinear Beam Equation, Carl E. Crockett
An Evolution Operator Solution For A Nonlinear Beam Equation, Carl E. Crockett
Theses and Dissertations
A nonlinear partial differential equation, motivated by the transverse vibration of a beam, is shown to have a unique solution. The existence theory, which is in the setting of semigroups and evolution operators, is a composite and synthesis of theorems of Kato. The formulation of the problem and the verification that the formulation leads to a solution are new. The introductory chapter provides background on the topic generally. Chapter 2 provides detailed formulations for the constant coefficient case. Chapter 3 describes nonautonomous cases. The general theorem is presented here. In Chapter 4, a more general case is considered. Namely, Kelvin …
A Whole Word And Number Reading Machine Based On Two Dimensional Low Frequency Fourier Transforms, Mark A. O'Hair
A Whole Word And Number Reading Machine Based On Two Dimensional Low Frequency Fourier Transforms, Mark A. O'Hair
Theses and Dissertations
The Fourier transform is investigated as a means for developing an optical reader capable of reading a large vocabulary without segmenting the image of a word into individual characters. The reader is capable of reading printed and cursive font styles, is scale invariant, and is substantially insensitive to noise. The image of a particular word is treated as a single symbol; the two dimensional low frequency Fourier coefficients (assuming n coefficients are calculated) define the word's location on an n dimensional hypersphere of unit radius. The distance between individual locations (words) categorizes similar and dissimilar words. The smaller the distance, …
Estimation Of Evoked Fields Using A Time-Sequenced Adaptive Filter With The Modified P-Vector Algorithm, Jeffery A. Kepley
Estimation Of Evoked Fields Using A Time-Sequenced Adaptive Filter With The Modified P-Vector Algorithm, Jeffery A. Kepley
Theses and Dissertations
This thesis describes a time sequenced adaptive filter developed to estimate visually evoked fields (EF) using visually evoked potentials (EP). These non-stationary signals are buried in strong background noise. The two types of noise are magnetoencephalogram (MEG) and electronencephalogram (EEG). The filter implementation is based on the Ferrara Time Sequenced Adaptive (TSAF) using the Least-Mean-Square (LMS) algorithm and the Williams modified P-vector algorithm (mPa). This essentially results in two filters. A two stage filter structure is used in which the first stage removes the time-varying mean of the input signals. This allows the second stage to process zero-mean signals which …
Bifurcation Analysis Of The Longitudinal Dynamics Of A Simple Powered Lifting Hypersonic Vehicle, Eric E. Fox
Bifurcation Analysis Of The Longitudinal Dynamics Of A Simple Powered Lifting Hypersonic Vehicle, Eric E. Fox
Theses and Dissertations
Bifurcation analysis was used to investigate the nonlinear behavior of a simple powered lifting hypersonic vehicle in circular orbit about a spherical nonrotating Earth with gradients in atmospheric density and pressure and an inverse square law for gravity. Vehicle motion is constrained to a vertical plane so only longitudinal dynamics were modeled. Bifurcation analysis was conducted using the AUTO software package. A simple five-state model with three different thrust laws was derived to describe an unaugmented vehicle whose geometric and aerodynamic characteristics follow those of the literature. A parameter representing a body flap deflection was used to conduct one set …
Modeling And Analysis Of Orthotropic Plate With Circular Cutout And Adhesive Bonded Patch, Mark W. Hunter
Modeling And Analysis Of Orthotropic Plate With Circular Cutout And Adhesive Bonded Patch, Mark W. Hunter
Theses and Dissertations
The purpose of this study was to investigate a modeling technique to simply and adequately model an adhesive bonded patch on an orthotropic plate. This report is limited to linear material behavior. This thesis is also the basis for further work into nonlinear material range and three-dimensional stress states. To further advance aerospace battle damage repair techniques for composite repairs, a finite element model of an orthotropic plate with a hole and patch was constructed to investigate the accuracy of such a model. The fundamental problem in this model is the development of a simple and accurate method of modeling …
Investigation Of The High Angle Of Attack Dynamics Of The F-15b Using Bifurcation Analysis, Robert J. Mcdonnell
Investigation Of The High Angle Of Attack Dynamics Of The F-15b Using Bifurcation Analysis, Robert J. Mcdonnell
Theses and Dissertations
Previous studies predicted the F-15B high angle of attack and flat spin behavior using bifurcation analysis. These studies varied control surface deflections to find equilibrium and periodic solutions. The purpose of this research was to use bifurcation analysis to predict the F-15B high angle attack and flat spin behavior as a result of variable thrust, asymmetric thrust, and thrust vectoring. Using a previously developed model of the F-15, bifurcation analysis and continuation methods were used to map out the equilibrium and periodic solutions of the model as a function of the thrust parameters. A baseline bifurcation diagram, as a function …
A Comparison Of Molecular Vibration Modeling For Thermal Nonequilibrium Airflow, Kenneth J. Moran
A Comparison Of Molecular Vibration Modeling For Thermal Nonequilibrium Airflow, Kenneth J. Moran
Theses and Dissertations
The effects of thermal nonequilibrium on flows about blunt-bodies have not been studied numerically in isolation from chemical reactions. Typically, air is modeled as a perfect gas or as a chemically reacting mixture. In the former case, significant errors result at Mach numbers exceeding about 5. However, below Mach numbers around 8, the effects of chemical reactions are negligible. This study analyzes flow about a simple axisymmetric blunt-body at moderate hypersonic speeds (Mach numbers between 5-8). A first-order-accurate Roe scheme was used to compute solutions of the Euler equations assuming different gas models: perfect gas, thermal equilibrium, and thermal nonequilibrium. …
H2 And H∞ Optimization With A Restricted Region Of Stability, Michael J. Mares
H2 And H∞ Optimization With A Restricted Region Of Stability, Michael J. Mares
Theses and Dissertations
Many modern control design methods, such as H2 and H∞ optimization, guarantee that the closed-loop system will be stable. To make further use of this guarantee, the portion of the s-plane considered to be stable is restricted to a region left of a vertical line some distance alpha from the imaginary axis. This alpha shift was accomplished in the state space equations, so standard computational tools still work. now the system is not only guaranteed to be stable, but also has some guaranteed speed for the time response. The equations for guaranteeing some arbitrary damping ratio were also …
Micromechanical Modeling Of The Fiber/Matrix Interface Region In A Metal Matrix Composite, David D. Robertson
Micromechanical Modeling Of The Fiber/Matrix Interface Region In A Metal Matrix Composite, David D. Robertson
Theses and Dissertations
In order to develop reasonable analytical models and to better understand how the integrity of the fiber/matrix interface in high temperature titanium based metal matrix composites effects the overall transverse normal characteristics, a parametric study of various fiber/matrix interface conditions was performed. Analysis methods included both a simplified one-dimensional mathematical model and a finite element analysis using MSC/NASTRAN. First, both strong and weak interfacial bonds were examined. Subsequently, to provide for partial bonding, a model that used an elastic-plastic interphases zone between the fiber and matrix was examined.
A Linear Quadratic Regulator Weight Selection Algorithm For Robust Pole Assignment, Jeffrey D. Robinson
A Linear Quadratic Regulator Weight Selection Algorithm For Robust Pole Assignment, Jeffrey D. Robinson
Theses and Dissertations
An advantage of linear quadratic regulator (LQR) design is that it gives a robust system by guaranteeing stability margins. This property is used to develop an algorithm for placing robust poles. The algorithm chooses the positive semidefinite weighting matrix Q and positive definite weighting matrix R by attempting to place closed loop poles at a set of desired poles. If the desired poles lie outside the allowable LQR region, the algorithm finds the achievable poles inside the region that are closest to the desired poles. The solution requires using a gradient search technique to minimize a weighted eigenvalue difference cost …
Modelling And Analysis Of Kernel Function And Development Of Equivalent Theodorsen Function For Three-Dimensional Aeroelastic Analysis, John K. Ryder
Modelling And Analysis Of Kernel Function And Development Of Equivalent Theodorsen Function For Three-Dimensional Aeroelastic Analysis, John K. Ryder
Theses and Dissertations
A fractional calculus model is developed for the kernal function under incompressible subsonic flow conditions for rectangular planform airfoils with small aspect ratio. A model valid for restricted regions of the kernel function for compressible subsonic flow conditions is also developed. Additionally, a method for numerically solving the pressure-downwash integral equation for rectangular planform wings of aspect ratio two through ten in incompressible flow is developed. An equivalent Theodorsen function for three- dimensional unsteady flow is developed, enabling the use of simpler two- dimensional aeroelastic equations of motion to fully capture the more complicated three-dimensional effects.
Computational Investigation Of Circulation Control Turbulence Modeling, T. Bryan Scruggs
Computational Investigation Of Circulation Control Turbulence Modeling, T. Bryan Scruggs
Theses and Dissertations
A computational study of the turbulence model parameters and the effect on the flow field of a circulation control airfoil was conducted. A Beam- Warming algorithm with a modified Baldwin-Lomax turbulence model was used to solve the Navier-Stokes equations. A comparison between the effects of the Bradshaw constant on the flow field about the cylinder and the flow field about an airfoil were to be made. The lack of a steady 'converged' solution for the cylinder precluded the analysis of the flow field about a cylinder. For the airfoil, the separation point moves rearward and an enhanced vortex pattern is …
Fluorescent Lifetime Measurements Of Rare Earth Elements In Gallium Arsenide, Danny J. Topp
Fluorescent Lifetime Measurements Of Rare Earth Elements In Gallium Arsenide, Danny J. Topp
Theses and Dissertations
Lifetime measurements of the excited states of three GaAs semiconductors doped with the rare earth elements Erbium (ER), Praseodymium (Pr) , and Thulium (Tm) has been studied using a pulsed nitrogen laser and germanium detector. The measurements were made with an experimental set up with a system response time of 0.34 micro seconds. A 330 milliwatt nitrogen laser with a wavelength of 3370 angstrums was used to excite transitions of the rare earth elements.
Use Of Grasp Force Focus Positioning To Enhance The Torque Resistance Capability Of Robotic Grasps, Stephen G. Edwards
Use Of Grasp Force Focus Positioning To Enhance The Torque Resistance Capability Of Robotic Grasps, Stephen G. Edwards
Theses and Dissertations
Three-point-contact grasps are unique in that the homogeneous solution for the contact forces always produces a grasp force focus. Careful positioning of this focus point in the grasp plane can help avoid two things; slipping at the contact points, and violation of joint torque limits. The focus placement method is explored theoretically by examining two types of grasps on cylinders; 1) fingertip grasps using three independently operated fingers, and 2) single-finger power grasps with one contact point on each of three links. Constraint maps are generated for various fingertip grasps in order to show how proper placement of the grasp …
A Comparison Of The Optimization And Analysis Of Doubly Curved Shells Using Msc/Nastran And Astros, John R. Dewsnap
A Comparison Of The Optimization And Analysis Of Doubly Curved Shells Using Msc/Nastran And Astros, John R. Dewsnap
Theses and Dissertations
This study identified techniques and software available for the optimization of doubly curved shells and applied them in the context of a large nozzle shape. An optimality criteria scheme that can reduce solution time was evaluated and compared to the Method of Feasible Directions. MSC/NASTRAN and ASTROS were used to perform finite element analysis and optimization, and the results were compared to the theory. The programs give virtually identical results, and if plates and shells are carefully modeled, then stresses, displacements and modes are accurate to within ten percent. A Mindlin-type axisymmetric finite element was implemented in ASTROS that preserved …
Analysis Of Periodic Orbits About The Martian Moons By Continuation Techniques, Frank Luria
Analysis Of Periodic Orbits About The Martian Moons By Continuation Techniques, Frank Luria
Theses and Dissertations
From a few known periodic orbits of Phobos and Deimos, continuation techniques were used to find entire families of stable orbits. These techniques involved varying a parameter, the Hamiltonian, of the system and analyzing how the orbital behavior changed with the parameter. Floquet multipliers, for stability analysis, were also computed. AUTO86, a continuation/bifurcation software package, was used in this study. Artificial energy dissipation had to be added to the conservative Hamiltonian system to enable use of AUTO.