Digital Commons Network^™

Comparison Of Afitpac Versus Nos And A Packet Radio Network Design, Thomas A. Iannelli

Theses and Dissertations

This thesis encompasses two themes: (1) A comparison of the Network Operating System (NOS) software package, developed by Phil Karn and others, and AFITPAC, written by Marsh and Geier at the Air Force Institute of Technology. The comparison is based on the Air Force Logistics Command's requirements for the development of a Packet Radio Network program. The results of the comparison are a recommendation that use of the NOS package be pursued because it can meet all twelve of the requirements and compiles with five of the Military Standard Protocols. (2) The design of a personal computer Packet Radio Network …

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 …

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

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 …

Image Analysis Using Gabor Transforms: Correlated With Human Saccadic Movement Data To Identify The Human Visual Search Strategy, Ralph J. St John

Theses and Dissertations

This thesis investigated whether a relationship exists between the Gabor Correlation Coefficient (GCC) magnitudes of fixation points for a set of images viewed by six subjects and the human visual search strategy. A couple of different relationships were investigated. First, the data were analyzed to determine if the GCC magnitudes of human fixation points predicted the time ordered sequence of human fixation points during the performance of a visual search. Second, the data were analyzed to determine if there was a significant difference between the GCC magnitudes of the human fixation points and the GCC magnitudes of a random set …

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 …

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 …

Improving Stochastic Communication Network Performance: Reliability Vs. Throughput, Leonard J. Jansen

Theses and Dissertations

This research investigated the measurement and improvement of two performance parameters, expected flow and reliability, for stochastic communication networks. There were three objectives of this research. The first was to measure the reliability of large stochastic networks. This was accomplished through an investigation into the current methodologies in the literature, with a subsequent selection and application of a factoring program developed by Page and Perry. The second objective was to develop a reliability improvement model given that a mathematical reliability expression did not exist. This was accomplished modeling a heuristic by Jain and Gopal, into a linear improvement model. Finally, …

Preliminary Design Of A Model To Assess The Effect Of Space Surveillance Network (Ssn) Sensor Upgrades On Orbit Prediction Accuracies Relative To The U. S. Anti-Satellite (Asat) Mission, Daniel L. O'Brien

Theses and Dissertations

This study gives a basis for implementation of a model to assess the effect of proposed sensor upgrades to the Space Surveillance Network (SSN) to determine if more accurate orbital element set predictions by the Space Surveillance Center (SSC) can be obtained for U.S. anti-satellite (ASAT) targeting. Handoff orbital element set predictions to nearby ASAT facilities for single, low-orbit satellite passes over a single radar sensor are considered. Model development began with simulation of the selected satellites passing over the selected sensors producing baseline truth observations based on the NORAD simplified General Publications (SGP4) model. Sensor errors, in the form …

A Formal Definition Of The Object-Oriented Paradigm For Requirements Analysis, Andrew D. Boyd

Theses and Dissertations

This paper develops a formal definition of the Object-Oriented paradigm for requirements analysis. The literature was surveyed for both formal and informal methods for conducting an Object-Oriented Requirements Analysis (OORA). The informal methods reviewed are: Bailin's, Shlaer and Mellor's, Booch's, and Coad and Yourdon's. The formal methods reviewed are: Bralick's, Z, and REFINE. None of the methods were found to be adequate for doing an OORA. A formal definition of an OORA, based on the concept of classes, is developed. The definition itself is presented as set and relation theory. A supporting graphical representation is also developed and presented. The …

Structured Hypermedia Application Development Model (Shadm): A Structured Model For Technical Documentation Application Design, Peter W. Cassell

Theses and Dissertations

This research was conducted to determine how a Royal Australian Air Force technical maintenance publication could be transformed into a task oriented hypermedia application and to develop a model that could be used for future similar transformations. The model was developed following in-depth analysis of the existing USAF F-15E maintenance publication set and validation was conducted using a prototype developed in HyperWriter, a commercial hypermedia product. The prototype model was based around the performance of three maintenance tasks on an aircraft sub-subsystem and incorporated online user access to the necessary support data for task completion. Publication managers, producers, and users …

Experimental Investigation Of Trailing Edge Crenulation Effects On Losses In A Compressor Cascade, Steven J. Decook

Theses and Dissertations

The effects of blade trailing edge crenulations on wake losses in a compressor cascade were investigated at the Air Force Institute of Technology. The cascade used NACA 64-A905 blades with a turning angle of about 30 to model last row stators of an axial flow compressor. Three blade configurations were used: unmodified blades, blades with large crenulations, and blades with small crenulations. Wake losses and mixing were evaluated in four flow conditions, generated by combinations of increased freestream turbulence and sidewall boundary layer removal. Injection of air perpendicular to the inlet flow increased freestream turbulence from about 0.15% to about …

Optimization Of Tangential Mass Injection For Minimizing Flow Separation In A Scramjet Inlet, Richard J. Kacik

Theses and Dissertations

With the reemergence of interest in air-breathing hypersonic propulsion, scramjet inlet efficiency has become an area of concern. The impingement of the engine cowl shock near the shoulder (expansion corner between forebody and combustor) may cause boundary layer separation which reduces inlet efficiency. Tangential mass injection (TMI) upstream of the shoulder has recently been tested to control this separation but without much parametric evaluation. To resolve this deficiency, a 2-D scramjet inlet model with variable length cowl, and TMI was built and tested in the WL Mach 6 High Reynolds Number Facility. Parameters varied were boundary layer thickness, TMI flow …

A Standardized Software Reliability Measurement Methodology, Joseph J. Stanko

Theses and Dissertations

Current Air Force practice is to perform Operational Test and Evaluation (OT and E) for each new weapons system. In support of this, Headquarters Air Force Operational Test and Evaluation Center (HQ AFOTEC) is responsible for measuring both suitability and effectiveness. While suitability is adequately measured, the current effort only addresses hardware effectiveness, or at best, system effectiveness. Since tools and metrics are in place for software suitability assessments related to OT and E (for example, software maintainability), there should be some effective way of measuring the operational effectiveness of software. Currently, HQ AFOTEC/LG5 has a data collection tool for …

Frequency Domain Speech Coding, Shane Switzer

Theses and Dissertations

The major goal of this research was to investigate speech coding techniques in an attempt to achieve high quality speech transmittable at 4800 bits per second. The approach taken to achieve this goal was to code the frequency domain representation of speech. Speech was represented by a sparse set of frequency components. Four frequency selections schemes were implemented, and the resulting frequency coefficients (magnitude and phase) were coded in an efficient manner for transmission. Specific techniques involved in the speech coder included: (1) a recurrent neural architecture to make a periodic/noiselike decision, (2) the use of variable length windows for …

Requirements Analysis For A Hardware, Discrete-Event, Simulation Engine Accelerator, Paul J. Taylor Jr.

Theses and Dissertations

An analysis of a general Discrete Event Simulation (DES), executing on the distributed architecture of an eight mode Intel PSC/2 hypercube, was performed. The most time consuming portions of the general DES algorithm were determined to be the functions associated with message passing of required simulation data between processing nodes of the hypercube architecture. A behavioral description, using the IEEE standard VHSIC Hardware Description and Design Language (VHDL), for a general DES hardware accelerator is presented. The behavioral description specifies the operational requirements for a DES coprocessor to augment the hypercube's execution of DES simulations. The DES coprocessor design implements …

Implementation Of An Object-Oriented Flight Simulator D.C. Electrical System On A Hypercube Architecture, Guy R. Booth

Theses and Dissertations

The Software Engineering Institute developed an Object-Oriented Paradigm for Flight Simulators based on the concept of mapping the behavior of physical objects from an aircraft into an object-oriented software architecture. This mapping is a semi-formal method that maps objects to a hierarchy that has three logical layers: objects, systems, and executives. The paradigm was developed with the idea of implementing the derived simulation design on a parallel or distributed computer architecture, but no explicity design features are provided for implementing the design on a parallel computer. This research addresses the issue of determining what extensions (if any) are required to …

Static Pressure Measurements Of A Low Power Arcjet, Kevin P. Talley

Theses and Dissertations

The NASA Lewis 1.2 kilowatt arcjet has been used for a number of performance and lifetime studies. This design was modified to obtain static pressure measurements at several locations along the arcjet nozzle. These measurements were taken at various propellant flow rates over most of the operational envelope of the thruster. Measured static pressure distributions are considerably higher than predicted by ID models and are proportional to the arc power. A simple thermodynamic model is also compared to the data, and is shown to match the slope of the data while overpredicting the pressure.

Parallel Implementation Of Vhdl Simulations On The Intel Ipsc/2 Hypercube, Ronald C. Comeau

Theses and Dissertations

VHDL models are executed sequentially in current commercial simulators. As chip designs grow larger and more complex, simulations must run faster. One approach to increasing simulation speed is through parallel processors. This research transforms the behavioral and structural models created by Intermetrics' sequential VHDL simulator into models for parallel execution. The models are simulated on an Intel iPSC/2 hypercube with synchronization of the nodes being achieved by utilizing the Chandy Misra paradigm for discrete-event simulations. Three eight-bit adders, the ripple carry, the carry save, and the carry-lookahead, are each run through the parallel simulator. Simulation time is cut in at …

A Comparative Analysis Of Computer End-User Support In The Air Force And Civilian Organizations, Maureen C. Casey, Douglas A. Kveene

Theses and Dissertations

This study compared end-user computing support provided by the Air Force to support provided by civilian organizations with information centers and those without. Factors measured included the end user's demographics, applications used, the effect of computing on perceived confidence, productivity, quality and quantity of output, the importance of various types of support, and satisfaction with the support received from different sources. A survey was administered to 450 Air Force and 265 civilian end users; 416 were returned (response rate of 58.18%). Although there were significant demographic differences between end users, there were no differences in types of support required. Training, …

An Analysis Of The Information Requirements Of Conus Based Deputy Commanders For Maintenance, Daniel J. Green

Theses and Dissertations

The purpose of this research was to identify the information requirements of Air Force Deputy Commanders for Maintenance. It had three basic objectives: (1) identify the critical success factors that they monitor on a continuous basis, (2) identify similarities in those requirements for all DGMs and across major commands, and (3) determine if the application of information technology would enhance their decision making. Surveys were sent to all CONUS based Deputy Commanders for Maintenance. The study found that there were nine critical success factors that were used by a majority of all respondents. In addition, nine command-specific critical success factors …

A Comparative Study Of Numerical Versus Analytical Waverider Solutions, Gregory O. Stecklein

Theses and Dissertations

The WL/FIMM explicit, Roe flux-splitting Euler algorithm is applied to the inviscid hypersonic flow over a parabolic-top waverider configuration optimized for Mach 10 at zero degrees angle of attack. An on-design grid refinement study is conducted to determine the asymptotic nature of the optimized flight parameter L/D. A parametric study of off-design conditions is conducted to determine flow perturbation effects on HSDT waverider theory. A validation of the Euler code is conducted through a comparison of the numerical data to analytical results derived by Rasmussen. The grid refinement study shows little effect on the inviscid calculation of the optimized parameter …

Function Prediction Using Recurrent Neural Networks, Randall L. Lindsey

Theses and Dissertations

A fully recurrent neural network was applied to the function prediction problem. The real-time recurrent learning (RTRL) algorithm was modified and tested for use as a viable function predictor. The modification gave the algorithm a variable learning rate and a linear/sigmoidal output selection. Verifying the networks ability to temporally learn both the classic exclusive-OR (XOR) problem and the internal state problem, the network was then used to simulate the frequency response of a second order IIR lowpass Butterworth filter. The recurrent network was then applied to two problems: head position tracking, and voice date reconstruction. The accuracy at which the …

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 …

Swatter (Space-Based Weapons Against Tactical Terrestrial-Based Resources): A Design For Integrating Space Into A Theater Level Wargame, Duane R. Cozadd

Theses and Dissertations

This thesis provides the foundation to expand the newly developed theater level computerized wargame, SABER, at the Air Force Wargaming Center, Maxwell AFB, Alabama to include space conflict at the theater level of simulation. Building upon the recently completed SABER, this thesis effort expands the conceptual framework of the model by integrating the dynamics of space warfare into the current theater level model. This expansion forms a new game called SWATTER. This thesis adds the space units required to integrate the land and air battles with the possible interactions from space. This thesis expands the stochastic attrition processes to include …

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 …

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 …

Acuta Enews November 1991, Vol. 20, No. 11

ACUTA Newsletters

In This Issue

President's message

Distance learning in Maine

FCC backs phone-line video

Pooling purchasing power

Area code shortage

Positions available

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 8, November 1991, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Analysis Of Baseband Equivalent Noise In A First-Order Correlation Loop Utilizing Filtered Pseudonoise Signals, Kurt Louis Kosbar, Christopher J. Scholten

Electrical and Computer Engineering Faculty Research & Creative Works

Conventional direct-sequence and frequency-hopping spread spectrum systems utilize delay-lock loops to track the timing epoch of pseudonoise codes. These devices perform admirably at high signal-to-noise ratios (SNR), however, they are suboptimal at moderate and low SNR. A correlation loop that employs appropriately filtered pseudonoise signals for the local cross-correlation waveform may have superior performance under these conditions. The performance of this modified correlation loop will be determined by the cross correlation function of the transmitted waveform and locally generated reference signals, along with the statistics of the baseband equivalent noise process. In this work, we find the statistics of the …