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Air Force Institute of Technology

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Articles 2671 - 2700 of 3051

Full-Text Articles in Physical Sciences and Mathematics

Unification Of Larch And Z-Based Object Models To Support Algebraically-Based Design Refinement: The Z Perspective, Kathleen M. Wabiszewski Dec 1994

Unification Of Larch And Z-Based Object Models To Support Algebraically-Based Design Refinement: The Z Perspective, Kathleen M. Wabiszewski

Theses and Dissertations

This research established a foundation for formalizing the evolution of based object models to theories, part of a dual approach for formally extending object-oriented analysis models using the Z and LARCH languages. For the initial phase, a comprehensive, consistent, and correct Z language parser was implemented within the SOFTWARE REFINERY™ Programming Environment. The Z parser produced abstract syntax trees (ASTs) of objects, thereby forming the basis for analyzing the similarities and differences between the based and LARCH-based object representations. The second phase used the analysis of the two languages to identify fundamental core constructs that consisted of similar syntactic and …

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Designing And Implementing An Ada Language Binding Specification For Odmg-93, Stephen R. Lindsay Dec 1994

Designing And Implementing An Ada Language Binding Specification For Odmg-93, Stephen R. Lindsay

Theses and Dissertations

Object-oriented database management systems (ODBMSs) represent the latest advancement in database technology, combining the reusability and maintainability of the object-oriented programming paradigm with the ability to efficiently store and retrieve a wide range of data types as well as code to manipulate stored data. Unfortunately, programmers developing software in the Ada programming language do not have the ability to interface to object databases without significant customized code development. One important reason for this has been the absence of a standard defining the constructs accessing ODBMS functionality. This thesis documents the creation of an Ada language binding to the ODMG-93 standard …

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Multiple Model Adaptive Estimation And Head Motion Tracking In A Virtual Environment: An Engineering Approach, James E. Russell Dec 1994

Multiple Model Adaptive Estimation And Head Motion Tracking In A Virtual Environment: An Engineering Approach, James E. Russell

Theses and Dissertations

Software engineering tools and techniques were applied to design and implement an application that reduces lag typically present in virtual environment displays. The application was a Multiple Model Adaptive Estimator (MMAE), composed of three Kalman filters, that predicted head orientation one sample period into the future. The environment rendering software used these predictions to generate the environment display. Each of the filters in the MMAE was designed for a different assumed head motion type (benign, moderate, or heavy), which allowed the MMAE to adapt to changes in head movement characteristics. The use of Ada 9X as an implementation language for …

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Development Of A Mammographic Image Processing Environment Using Matlab, John L. Kelley Dec 1994

Development Of A Mammographic Image Processing Environment Using Matlab, John L. Kelley

Theses and Dissertations

Breast cancer is a disease that accounts for a disturbingly large number of deaths in females each year. Its prevalence is a topic of concern to all of us since it can affect our families, friends, and coworkers. Although mammographic screening is the most effective method currently available for the early detection of breast cancer, it is far from being an infallible procedure. Mammographic reading is error prone, partly because of the complexity of the task and partly because of the variability in human performance. Computers offer high reproducibility, and when used as an adjunct by the radiologist, may improve …

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Improving Intrusion Detection In Unix-Based Networks, David R. Landry Dec 1994

Improving Intrusion Detection In Unix-Based Networks, David R. Landry

Theses and Dissertations

Computer security has not kept pace with the rapid growth of networked systems. Through its connection to the Internet, the Department of Defense is vulnerable to computer-based attacks. Current intrusion detection systems are still unproven, too complicated, or too costly for most system security officers to implement. The attack methods used by system intruders are known and can be represented as groups of commands called attack signatures. This thesis investigates methods for detecting intruders by monitoring command usage. Testing was conducted in both controlled and uncontrolled circumstances. With controlled testing, it was shown that 7 of the 11 signatures could …

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Laser Beam Propagation In Non-Kolmogorov Atmospheric Turbulence, Bruce E. Stribling Dec 1994

Laser Beam Propagation In Non-Kolmogorov Atmospheric Turbulence, Bruce E. Stribling

Theses and Dissertations

Several observations of atmospheric turbulence statistics have been reported which do not obey Kolmogorov's power spectral density model. These observations have prompted the study of optical propagation through turbulence described by non-classical power spectra. This thesis presents an analysis of optical propagation through turbulence which causes index of refraction fluctuations to have spatial power spectra that obey arbitrary power laws. The spherical and plane wave structure functions are derived using Mellin transform techniques and are applied to the field mutual coherence function (MCF) using the extended Huygens-Fresnel principle. The MCF is used to compute the Strehl ratio of a focused, …

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Computing Norad Mean Orbital Elements From A State Vector, Dwight E. Andersen Dec 1994

Computing Norad Mean Orbital Elements From A State Vector, Dwight E. Andersen

Theses and Dissertations

NORAD maintains and disseminates mean orbital elements on Earth-orbiting satellites in the form of Two-Line Element Sets (TLE). Five mathematical propagator models were developed for NORAD's use to predict the position and velocity using TLEs. This study investigated two approaches, Newton's method and direct iteration, to inverting this process by iterating to obtain NORAD-compatible mean orbital elements from a position and velocity state vector and the drag term. The Newton's iteration method was developed but not tested. The less computationally intensive direct iteration method was developed, coded in FORTRAN, and tested. The initial guess and subsequent corrections in the iterative …

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A Correlational Study Of The Sei's Capability Maturity Model And Software Development Performance In Dod Contracts, Robert M. Flowe, James B. Thordahl Dec 1994

A Correlational Study Of The Sei's Capability Maturity Model And Software Development Performance In Dod Contracts, Robert M. Flowe, James B. Thordahl

Theses and Dissertations

The Software Engineering Institute's (SEl's) Capability Maturity Model (CMM) is to measure an organization's software development process maturity. The Department of Defense (DoD) has model with the belief that a more mature software development process will result in a more successful software subject. Although there is a growing body of anecdotal evidence supporting this presumed correlation, there is empirical evidence. Thus, the goal of our research was to determine the nature of the correlation, if any, :ware process maturity and software project success, where process maturity is based on a CMM rating and success based on the parameters of cost …

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Factors In Human-Computer Interface Design (A Pilot Study), Susan Stewart Dec 1994

Factors In Human-Computer Interface Design (A Pilot Study), Susan Stewart

Theses and Dissertations

The DoD has budgeted over $9.8 billion for 1995 for information technology, yet many government office workers let their existing systems sit idle. This thesis explores why these computers are sitting idle. This researcher's initial hypothesis was that certain features of the human-computer interface can positively or negatively affect efficiency, retention, and satisfaction level of workers. Although some research is being done in this area, interfaces continue to be of poor quality, especially in the DoD, where long procurement cycles, forced purchases, and limited budgets result in out-of-date software. Intuitively most programmers know the human-computer interface impacts on a person's …

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Flow Visualization Of A Turbulent Shear Flow Using An Optical Wavefront Sensor, Daniel W. Jewell Dec 1994

Flow Visualization Of A Turbulent Shear Flow Using An Optical Wavefront Sensor, Daniel W. Jewell

Theses and Dissertations

The research reported here investigated the use of a shearing interferometer (SI) wavefront sensor to determine the effects of shear-layer turbulence on an optical wavefront. A collimated helium-neon laser beam was propagated through a plane shear-layer produced by mixing helium and nitrogen at different velocities. Since the gases have different indices of refraction, the optical wavefront was distorted by different amounts by each gas. The SI measured the wavefront slope across the sampled area of the wavefront. The shear-layer was viewed from two orthogonal directions. This document contains shadow graphs, interference patterns imaged by each of the SI's six cameras, …

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Feasibility Exploration Of Throughfold As A Predictor For Target Loading And Associated Error Bounds, Kris G. Rongone Dec 1994

Feasibility Exploration Of Throughfold As A Predictor For Target Loading And Associated Error Bounds, Kris G. Rongone

Theses and Dissertations

Various applications of the Fredholm integral equation appear m different fields of study. An application of particular interest to the Air Force arises in determination of target loading from nuclear effects simulations. Current techniques first unfold the incident spectrum then determine target loading; resulting spectrum and loading are assumed exact. This study investigates the feasibility of a new method, through-fold, for directly determining defensible error bounds on target loading. Through-fold uses a priori information to define input data and represents target response with a linear combination of instrument responses plus a remainder to derive a quadratic expression for exact target …

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Design And Implementation Of Tools To Increase User Control And Knowledge Elicitation In A Virtual Battlespace, Jim J. Rohrer Nov 1994

Design And Implementation Of Tools To Increase User Control And Knowledge Elicitation In A Virtual Battlespace, Jim J. Rohrer

Theses and Dissertations

AFIT's Synthetic BattleBridge is an immersive command observatory for viewing large-area activity within a virtual environment. Three basic areas for improvement are addressed: (1) an improved, immersive, user interface, (2) direct control of atmospheric effects, and (3) improved knowledge elicitation by means of remote viewers, a new space scope, and an enhanced RADAR scope. These requirements are analyzed and implemented. Some functionality was lost but the results show a general improvement of environmental control and knowledge elicitation.

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A Numerical Analysis Of Smoothed Particle Hydrodynamics, David A. Fulk Sep 1994

A Numerical Analysis Of Smoothed Particle Hydrodynamics, David A. Fulk

Theses and Dissertations

This dissertation studies the numerical method of Smoothed Particle Hydrodynamics SPH as a technique for solving systems of conservation equations. The research starts with a detailed consistency analysis of the method. Higher dimensions and non-smooth functions are considered in addition to the smooth one dimensional case. A stability analysis is then performed. Using a linear technique, an instability is found. Solutions are proposed to resolve the instability. Also a total variation stability analysis is performed leading to a monotone form of SPH. The concepts of consistency and stability are then used in a convergence proof. This proof uses lemmas derived …

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Optimal Pulsed Pumping For Aquifer Remediation When Contaminant Transport Is Affected By Rate-Limited Sorption: A Calculus Of Variation Approach, Richard T. Hartman Sep 1994

Optimal Pulsed Pumping For Aquifer Remediation When Contaminant Transport Is Affected By Rate-Limited Sorption: A Calculus Of Variation Approach, Richard T. Hartman

Theses and Dissertations

The remediation of groundwater contamination continues to persist as a social and economic problem due to increased governmental regulations and public health concerns. Additionally, the geochemistry of the aquifer and the contaminant transport within the aquifer complicates the remediation process to restore contaminated aquifers to conditions compatible with health-based standards. Currently, the preferred method for aquifer cleanup pump-and-treat has several limitations including, the persistence of sorbed chemicals on soil matrix and the long term operation and maintenance expense. The impetus of this research was to demonstrate that a calculus of variations approach could be applied to a pulsed pumping aquifer …

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Development Of An Analysis Method To Identify The Root Causes Of Finding From The Air Force Environmental Compliance Assessment And Management Program (Ecamp), Frederick B. Cade Sep 1994

Development Of An Analysis Method To Identify The Root Causes Of Finding From The Air Force Environmental Compliance Assessment And Management Program (Ecamp), Frederick B. Cade

Theses and Dissertations

The Air Force is committed to being a national leader in achieving environmental compliance. This commitment is exemplified by the Air Force Chief of Staffs goal of no 'notices of violation.' This goal, however, has proven to be elusive. In the early 1990s, the number of Air Force notices of violation (NOVs) increased by 73%, from 103 to 178. One of the reasons may be findings from the Environmental Compliance Assessment and Management Program (ECAMP) are not being utilized effectively. This research developed an analysis method to identify root causes of ECAMP findings. The model emphasized the use of performance …

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Experiment Using Infrared Spectroscopy To Study The Effect Of Soil Characteristics Upon The Rate Of Trichloroethylene Desorption, Benjamin T. Kindt Sep 1994

Experiment Using Infrared Spectroscopy To Study The Effect Of Soil Characteristics Upon The Rate Of Trichloroethylene Desorption, Benjamin T. Kindt

Theses and Dissertations

This research investigated the influence of soil characteristics on the desorption of trichloroethylene (TCE). TCE is one of the most common contaminants at Superfund sites. Unfortunately, extraction of TCE from contaminated soils has been hindered by its slow and poorly understood desorption from soil particles. The rate and progress of desorption of TCE from seven types of soil with varying particle diameters and elemental compositions was measured using optical absorption techniques. Fitting the data to the Langmuir Isotherm functional form predicted in the literature yielded parameters for the desorption rate and total amount desorption each soil type. These parameters were …

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A Three Region Analysis Of A Bounded Plasma Using Particle In Cell And Fluid Techniques, Don F. Nichols Sep 1994

A Three Region Analysis Of A Bounded Plasma Using Particle In Cell And Fluid Techniques, Don F. Nichols

Theses and Dissertations

A detailed collisionless sheath theory and a three-region collisional model of a bounded plasma are presented, and the suitability of the collisional model for analysis of ignited mode thermionic converters is investigated. The sheath theory extends previous analyses to regimes in which the sheath potential and electron temperatures are comparable in magnitude. In all operating regimes typical of a ignited mode thermionic converter, the predicted sheaths extend several mean-free paths. The apparent collisionality of the sheaths prompted development of a collisional, three-region model of the converter plasma. By interfacing Particle-in-Cell regions for the sheaths and fluid regions for the bulk …

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Exposure Of A Food Crop To Trichloroethylene From A Contaminated Aquifer, Richard G. Baringer Sep 1994

Exposure Of A Food Crop To Trichloroethylene From A Contaminated Aquifer, Richard G. Baringer

Theses and Dissertations

This research developed a methodology for assessment of the exposure of a mature corn crop to trichloroethylene from a contaminated aquifer. The methodology was then applied to the case of Hill AFB to determine the ability of the methodology to provide information about a specific exposure. Current procedures sample for food contamination but do not attempt to predict exposure problems. A review of the potential exposure pathways from the aquifer to the crop was conducted. Based on this review, the exposures due to soil gas and irrigation were modeled. Empirical estimated were used to approximate the expected flux of soil …

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Experiment In Water Dowsing, David I. Gaisford Sep 1994

Experiment In Water Dowsing, David I. Gaisford

Theses and Dissertations

Dowsing is a folklore process used to locate an unknown, such as the best location for a water well, by the use of a hand-held device. The process is commonly know as water witching, divining, dowsing or radiesthesia. The practice continues despite the lack of a proven scientific basis. This research develops an experiment to test the claims of a dowser. Specific procedures are established and statistical theory is applied to determine if one man can identify which of five water lines has flowing water in it better than a chance operator could achieve. The statistical analysis uses Abraham Wald's …

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Modeling Trihalomethane Formation Potential From Wastewater Chlorination, Carol A. Mccormick Sep 1994

Modeling Trihalomethane Formation Potential From Wastewater Chlorination, Carol A. Mccormick

Theses and Dissertations

The deletion of federally mandated fecal coliform limits has led many states to review and modify their wastewater disinfection requirements. One issue in analyzing wastewater disinfection is the discharge of potentially carcinogenic halogenated organics formed during the chlorination process. This research investigates the formation of one class of the halogenated organics, the trihalomethanes. The applicability of using drinking water trihalomethane formation models for use with wastewater effluent is examined. Three models are compared for predictive capability by using measured trihalomethane values from previous research data. The results show that a previously developed model is applicable for use based on assumptions …

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High Resolution Fourier Transform Spectroscopy Of The First Overtone Of The N-O Stretch In Nitrosyl Bromide, Todd E. Wiest Sep 1994

High Resolution Fourier Transform Spectroscopy Of The First Overtone Of The N-O Stretch In Nitrosyl Bromide, Todd E. Wiest

Theses and Dissertations

Infrared Fourier transform spectroscopy of the first overtone of the nitric oxide (NO) bond stretch in nitrosyl bromide (ONBr) has been performed at a resolution of 0.02cm-1 to obtain the rotational parameters of the V1 = 2 energy level. Roughly 1000 transitions have been observed for rotational levels up to J = 80 and Ka = 7. The calculation of the complete set of rotational energy levels of this asymmetric molecule requires the numerical diagonalization of four, tridiagonal matricies for each J. From a non-linear least squares fit of observed transitions with J ≤ 40 using an …

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Coherence And Usability Of An Environmental Impact Statement, Jill A. Easterly Sep 1994

Coherence And Usability Of An Environmental Impact Statement, Jill A. Easterly

Theses and Dissertations

The purpose of this research effort was to investigate the application of certain principles of effective communication to improve the comprehension, and ultimately the usability, of an Environmental Impact Statement (EIS). Principles from cohesion theory (an area of research describing effective design) were used to manipulate the design of select sections of two sample EISs. Each sample EIS was altered to manipulate the presence and/or absence of visual and linguistic cohesion. Subjects were required to read select versions from each section of the two sample EISs and answer four short answer questions. The dependent variables were accuracy in answering the …

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How Effective Has The Air Force Been In Eliminating Its Dependence On Ozone Depleting Chemicals?, L. Susan Willard Sep 1994

How Effective Has The Air Force Been In Eliminating Its Dependence On Ozone Depleting Chemicals?, L. Susan Willard

Theses and Dissertations

This research was undertaken to determine how effectively the Air Force had eliminated its dependence on Ozone Depleting Chemicals. The research was limited to analyzing the impact of ODCs on major acquisition programs. Results indicated existing variables which may be impeding full implementation. Also identified were lessons learned which could be applied to future environmental legislation with potential impact on acquisition programs. In- depth telephonic interviews were conducted with Program Directors responsible for the development and fielding of major Air Force acquisition programs. Analysis revealed that ODCs substantially impacted the acquisition programs to the extent that many programs had classified …

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Simulation Of Hydrologic Influences On Wetland Ecosystem Succession, Robert A. Pompilio Sep 1994

Simulation Of Hydrologic Influences On Wetland Ecosystem Succession, Robert A. Pompilio

Theses and Dissertations

This research focuses on the development of a simulation model to determine the effects of hydrological influences on a wetland ecosystem. The model allows perturbations to the inputs of various wetland data which in turn, influences the successional development of the ecosystem. This research consisted of converting a grassland ecosystem model to one which simulates wetland conditions. The critical factor in determining the success of wetland creation is the hydrology of the system. There are four of the areas of the original model which are affected by the hydrology. The model measures the health or success of the ecosystem through …

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Modeling Of Ground Water Aquifer Remediation By Pulsed Pumping When Contaminant Transport Is Affected By Physical, Non-Equilibrium Sorption And Desorption, Jeffrey L. Caspers Aug 1994

Modeling Of Ground Water Aquifer Remediation By Pulsed Pumping When Contaminant Transport Is Affected By Physical, Non-Equilibrium Sorption And Desorption, Jeffrey L. Caspers

Theses and Dissertations

This research postulates and demonstrates a modification incorporating rate-limited sorption effects in the USGS SUTRA code for cleanup of a hypothetical sandy aquifer by pump-and-treat remediation methods. Contaminant transport is assumed to be affected by advection, dispersion, and rate-limited sorption/desorption. Sorption is assumed to be either equilibrium or rate-limited, with the rate-limitation described by either a first-order law, or by Fickian diffusion of contaminant through a spherical immobile pore region. Solutions are arrived at by split operator methods for the transport and one-dimensional Galerkin solutions for the solute concentration equations. The resulting model is tested against an analytical Laplace transform …

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The Optical Emission And Absorption Properties Of Silicon-Germanium Superlattice Structures Grown On Non-Conventional Silicon Substrate Orientation, Theodore L. Kreifels Aug 1994

The Optical Emission And Absorption Properties Of Silicon-Germanium Superlattice Structures Grown On Non-Conventional Silicon Substrate Orientation, Theodore L. Kreifels

Theses and Dissertations

Optical emission and absorption properties of Si1-x Gex/Si superlattices grown on (100), (110), and (111) Si substrates were investigated to determine the optimal growth conditions for these structures to be used as infrared detectors. Fully-strained Si1-x Gex/Si superlattices were grown by molecular beam epitaxy MBE and examined using low-temperature photoluminescence PL to identify no-phonon and phonon-replica interband transitions across the alloy bandgap. Phonon-resolved emission was most intense for undoped quantum wells grown at 710°C for all three silicon orientations. Room temperature absorption measurements were conducted on (100) and (110) Si1-x Gex/Si …

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Use Of Infrared Spectrometry To Determine The Effect Of Temperature On The Description Rates Of Trichloroethylene From Plastic Clay 98b, Abdellatif Fares Aug 1994

Use Of Infrared Spectrometry To Determine The Effect Of Temperature On The Description Rates Of Trichloroethylene From Plastic Clay 98b, Abdellatif Fares

Theses and Dissertations

This thesis investigated the influence of temperature on the desorption rated of trichloroethylene (TCE) from plastic clay. It was expected that an increase in temperature will cause an increase in both the desorption rates of TCE and in the desorbed quantity. Previous studies on other chemicals indicated a faster decrease in the remaining sorbed concentration with an increase in temperature. This research made use of the infrared optical absorption technique. IR spectroscopy was used to measure the concentration of the vapor TCE that desorbed from the soil. The soil was exposed to liquid TCE for 2 days then placed inside …

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Analysis Of The Potential For Plant Uptake Of Trichloroethylene And An Assessment Of The Relative Risk From Different Crop Types, Roy-Alan C. Agustin Jul 1994

Analysis Of The Potential For Plant Uptake Of Trichloroethylene And An Assessment Of The Relative Risk From Different Crop Types, Roy-Alan C. Agustin

Theses and Dissertations

This research expands our limited knowledge on the influence of plants on the fate and effects of trichloroethylene (TCE), providing a screening tool on which to base decisions regarding the need for actual sampling of plants. First, physicochemical properties of TCE--vapor pressure, Henry's Law constant, water solubility, octanol-water partition coefficient, molecular weight, and half-life--were screened against relationships reported in literature to evaluate TCE plant uptake potential. This screening approach indicated TCE may be transferred to plants via retention by root surfaces, root uptake and translocation, and foliar uptake. Next, the PLANTX model developed by Trapp and others was applied to …

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Spatio-Temporal Pattern Recognition Using Hidden Markov Models, Kenneth H. Fielding Jun 1994

Spatio-Temporal Pattern Recognition Using Hidden Markov Models, Kenneth H. Fielding

Theses and Dissertations

A new spatio-temporal method for identifying 3D objects found in 2D image sequences is presented. The Hidden Markov Model technique is used as a spatio-temporal classification algorithm to identify 3D objects by the temporal changes in observed shape features. A new information theoretic argument is developed that proves identifying objects based on image sequences can lead to higher classification accuracies than single look methods. A new distance measure is proposed that analyzes the performance of Hidden Markov Models in a multi-class pattern recognition problem. A three class problem identifying moving light display objects provides experimental verification of the sequence processing …

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Feature And Model Selection In Feedforward Neural Networks, Jean M. Steppe Jun 1994

Feature And Model Selection In Feedforward Neural Networks, Jean M. Steppe

Theses and Dissertations

This research advances feature and model selection for feedforward neural networks. Feature selection involves determining a good feature subset given a set of candidate features. Model selection involves determining an appropriate architecture number of middle nodes for the neural network. Specific advances are made in neural network feature saliency metrics used for evaluating or ranking features, statistical identification of irrelevant noisy features, and statistical investigation of reduced neural network architectures and reduced feature subsets. New feature saliency metrics are presented which provide a more succinct quantitative measure of a features importance than other similar metrics. A catalogue of feature saliency …

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