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Air Force Institute of Technology

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Articles 3061 - 3078 of 3078

Full-Text Articles in Physical Sciences and Mathematics

A Comparison Of Human-Computer Interfaces In Air Force Organizations, Michael G. Morris Dec 1990

A Comparison Of Human-Computer Interfaces In Air Force Organizations, Michael G. Morris

Theses and Dissertations

This thesis investigated differences in organizational efficiency and effectiveness for users of graphical user interfaces and text-based interfaces on personal computers in Air Forces offices. Areas of interest included amount of time required to learn the basic system, amount of time required to learn new application, users' ratings of user-friendliness, users' perceptions of the extent that their system help them perform in their job, the number of software packages used on the job by users of each system, user satisfaction, responsible authorities' ratings of quality of output, and the relationship between user job experience level and interface used on the …

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An Evolution Operator Solution For A Nonlinear Beam Equation, Carl E. Crockett Dec 1990

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 …

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Characterization Of Barium Titanate As An Optical Amplifier, George A. Vogel Dec 1990

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 …

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Analysis Of Periodic Orbits About The Martian Moons By Continuation Techniques, Frank Luria Dec 1990

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.

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A Whole Word And Number Reading Machine Based On Two Dimensional Low Frequency Fourier Transforms, Mark A. O'Hair Dec 1990

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, …

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An Object Oriented Design And Implementation Of The Idef0 Essential Data Model Using Ada And An Ada Based Expert System, Terry L. Kitchen Dec 1990

An Object Oriented Design And Implementation Of The Idef0 Essential Data Model Using Ada And An Ada Based Expert System, Terry L. Kitchen

Theses and Dissertations

This thesis develops and implements an Ada based object oriented design (OOD) of the IDEF0 Essential Data Model called the Essential Subsystem, which includes an Ada based expert system for IDEF0 model syntax checking. IDEF0 is a graphic approach to system description development by SofTech, Inc. for the U.S. Air Force Program for Integrated Computer Aided Manufacturing (ICAM) and is a subset of the Structured Analysis (SA) language (30, 36). The IDEF0 Essential Data Model is an entity-relationship (E-R) model of the IDEF0 language and represents the fundamental (essential) information of an IDEF0 model. …

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An Object-Oriented Military Simulation Baseline For Parallel Simulation Research, Robert J. Rizza Dec 1990

An Object-Oriented Military Simulation Baseline For Parallel Simulation Research, Robert J. Rizza

Theses and Dissertations

This thesis documents the design and implementation of a discrete event military simulation using a modular object-oriented design and the C programming language. The basis simulation is one of interacting objects. The objects move along a predetermined path until they encounter another object. Objects react to the encounter object according to the implemented algorithm. Object reaction options are fight, evade, or do nothing. In the code's current form it is generic enough to allow a user the flexibility of creating an infinite number of scenarios bounded in size by the hardware's memory capacity. The modularity of design will allow for …

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Detection Of High Altitude Aircraft Wake Vortices Using Infrared Doppler Lidar: An Assessment, Michael J. Estes Dec 1990

Detection Of High Altitude Aircraft Wake Vortices Using Infrared Doppler Lidar: An Assessment, Michael J. Estes

Theses and Dissertations

This thesis investigated the feasibility of air-to-air detection of high altitude aircraft wake vortices at long ranges using infrared Doppler lidar. The purpose of this technique is to detect otherwise stealthy aircraft. Three laser wavelengths were analyzed: 1.064, 2.091, and 9.115 microns. Analysis revealed that the spectral width of the return signal from an aircraft wake presented a good signature for detection. Based on the analysis, a minimum signal-to-noise ratio of 0 db was established. Detection performance was then analyzed using signal-to-noise ratio calculations for backscatter by ambient atmospheric aerosols, jet engine exhaust soot particles, and condensation trail ice particles. …

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Continuous Wave And Pulsed Solid State Laser Model, Matthew D. Rotondaro Nov 1990

Continuous Wave And Pulsed Solid State Laser Model, Matthew D. Rotondaro

Theses and Dissertations

A solid state laser is modeled for use on a personal computer. The model can accurately represent Nd:YAG and Nd:Glass lasers during both continuous wave and repetitively pulsed operation. The large number of input variables allow the user to make changes to the cavity, optical pump source, and the cooling system. The model calculates the energy, power, and divergence angle of the beam along with other variables. Because of its user-friendly interface, it is possible for someone with limited laser experience to obtain useful information.

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Monte Carlo Simulation Of Atmospheric Neutron Transport At High Altitudes Using Mcnp, Donald R. Culp, David L. Monti, James R. Shoemaker, David Wesley, Kirk A. Mathews Aug 1990

Monte Carlo Simulation Of Atmospheric Neutron Transport At High Altitudes Using Mcnp, Donald R. Culp, David L. Monti, James R. Shoemaker, David Wesley, Kirk A. Mathews

AFIT Documents

Neutron transport calculations were performed using the Monte Carol code, MCNP. The transport problem considered has a point source at high altitude (40 km). Since atmospheric density decreases with altitude, two-dimensional effects (cylindrical coordinates) can be important. Results were compared to those obtained with the SMAUG-II computer code, which performs mass-integral scaling of approximate fits to one-dimensional spherical discrete ordinates solutions. These comparisons show the importance of two-dimensional computations. The report discusses practical issues of applying MCNP to this problem, without code modifications and includes example input files for MCNP and for SMAUG-II. Computational modelling of neutron transport in the …

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An Abstract Data Model For The Idef0 Graphical Analysis Language, Gerald R. Morris, Thomas C. Hartrum, Mark A. Roth Jan 1990

An Abstract Data Model For The Idef0 Graphical Analysis Language, Gerald R. Morris, Thomas C. Hartrum, Mark A. Roth

AFIT Documents

IDEF0 is the United States Air Force's ICAM (Integrated Computer Aided Manufacturing) Definition Method Zero graphical analysis language, a subset of Ross' Structured Analysis (SA) language. The language is also an excellent methodology for performing a requirements-phase analysis for any software development project. We present an abstract data model for IDEF0 using entity-relationship diagrams. This model helps to mitigate some of the ambiguities inherent in IDEF0. The model is divided into two parts representing the analysis data (the essential data model) and the graphical data (the drawing data model). This dual modeling approach allows for the …

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Synthetic Aperture Multi-Telescope Tracker Apparatus, Richard A. Carreras, Salvatore J. Cusumano, Morton B. Jenks, Robert I. Suizu May 1987

Synthetic Aperture Multi-Telescope Tracker Apparatus, Richard A. Carreras, Salvatore J. Cusumano, Morton B. Jenks, Robert I. Suizu

AFIT Patents

A plurality of telescopes provide output return signals which are applied both directly and in sampled form to a photo-detector cell. The detected signals from the photo-detector will represent the constant and transient errors of the telescope system. A low pass filter insures that the tracker provides only the constant or D.C. component of the error, while a high pass filter insures that the existing measuring devices for each telescope beam provide only the transient or A.C. component of the error. The A.C. and D.C. error signals are summed together with the appropriate applied gains on each channel such that …

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Optically Phased Laser Transmitter, Janet S. Fender, Salvatore J. Cusumano, Robert R. Butts, Christopher R. Dehainaut Jan 1987

Optically Phased Laser Transmitter, Janet S. Fender, Salvatore J. Cusumano, Robert R. Butts, Christopher R. Dehainaut

AFIT Patents

An apparatus and technique are described for phasing the outputs of a multiplier telescope array used as a laser transmitter. The technique uses samples of the transmitted beams to control optical path lengths through the separate telescopes so that the beams add coherently at the receiver. The phasing concept is applicable both to systems which provide inputs to the multiple telescopes by dividing a single laser beam and to systems in which the inputs to the telescopes and multiple, phase-locked laser beams. The approach is also compatible with single line and multi-line lasers, and it does not entail stringent alignment …

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Stochastic Estimation Applied To The Land Speed Of Sound Record Attempt By A Rocket Car, David A. Reinholz Dec 1983

Stochastic Estimation Applied To The Land Speed Of Sound Record Attempt By A Rocket Car, David A. Reinholz

Theses and Dissertations

Optimal linear smoothing theory is applied to the data from the Speed of Sound record attempt of a three-wheeled rocket car on 17 December 1979. A forward-backward estimation method is used which employs a seven state forward-running extended Kalman filter and a Meditch-form backward recursive 'fixed-interval' smoothing algorithm. Data for this analysis is supplied by a longitudinal accelerometer mounted on the vehicle and tracking radar measurements of range, azimuth, and elevation. States of interest include two components of vehicle position and velocity, accelerometer time-correlated error, and radar range and azimuth bias errors. Two iterations of the forward-backward smoothing algorithm provide …

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Global Bifurcation Theorems For Nonlinearly Perturbed Operator Equations, John Macbain Jan 1976

Global Bifurcation Theorems For Nonlinearly Perturbed Operator Equations, John Macbain

Faculty Publications

No abstract provided.

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Lasing Conditions Of Elemental Sulfur In A Gas Discharge, David E. Egbert Sep 1972

Lasing Conditions Of Elemental Sulfur In A Gas Discharge, David E. Egbert

Theses and Dissertations

The partial pressures from heated sulfur crystals and helium, and sulfur and nitrogen required for ionic sulfur laser action in a gas discharge were determined. Previous work with sulfur lasers is reviewed and population inversion mechanisms are presented for the ionic sulfur laser lines. Possible excitation mechanisms are presented for both electron and ion or atomic collision excitation. Transition diagrams for all the known ionic sulfur laser transitions and an approximate potential energy curve for the diatomic sulfur molecule are presented. Laser action was achieved only when a spark gap pulser was used with a laser tube especially designed to …

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Software Simulation Of The D17b Computer, Bruce Chatterton Mar 1972

Software Simulation Of The D17b Computer, Bruce Chatterton

Theses and Dissertations

A software program has been written which simulates the functions of the Minuteman D17B computer at the register transfer level. The simulation program is written in the FORTRAN Extended language to be used on the Intercom System (teletype) of a CDC 6600 computer system. The simulation program consists of a main program and eight subroutines. A programming language for the D17B simulation was formed which contains numbers and load codes, switches, and miscellaneous commands. Example programs run on the simulated computer have been included to show the types of output available.

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Investigation Of The Platinum-Rich Portion Of The Platinum-Tantalum Phase Diagram, Bob Dean Browning Aug 1961

Investigation Of The Platinum-Rich Portion Of The Platinum-Tantalum Phase Diagram, Bob Dean Browning

Theses and Dissertations

The Pt-Ta binary system was investigated at two isotherms;1000°C and 1500°C, and at eleven alloy compositions in the range of 50 to 100 atomic percent platinum. The alloys were examined by x-ray diffraction and metallography. Three intermetallic compounds, Pt2Ta, Pt3Ta, and Pt4Ta were found to exist in this composition range. The Pt4Ta intermetallic appeared only at the 1500°C isotherm. Platinum dissolved tantalum substitutionally to 90 atomic percent at 1500 °C and to approximately 80 atomic percent at 1000 °C.

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