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Air Force Institute of Technology

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Articles 2221 - 2250 of 2678

Full-Text Articles in Physical Sciences and Mathematics

Unfolding The High Energy Electron Flux From Crres Fluxmeter Measurements, Brian D. Mckellar Dec 1996

Unfolding The High Energy Electron Flux From Crres Fluxmeter Measurements, Brian D. Mckellar

Theses and Dissertations

The Combined Release and Radiation Effects Satellite (CRRES) was launched on 25 July 1990 to collect measurements in the earth's radiation belts. One instrument, the High Energy Electron Fluxmeter (HEEF), measured the flux of electrons in 10 channels with energies between 1 MeV and 10 MeV. The channel sensitivities, Ri(E), have been calibrated and partially re-calibrated. We explore the errors introduced in unfolding the electron flux spectrum from the channel measurements and the propagation and growth of calibration and measurement errors. Using numerical experimentation, we fold the responses with known spectra to obtain simulated measurements, add random measurement and calibration …

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Implementation Of An Ada95 Crosscompiler For The Real-Time Executive For Military Systems (Rtems), Kendall M. Lemley Jr. Dec 1996

Implementation Of An Ada95 Crosscompiler For The Real-Time Executive For Military Systems (Rtems), Kendall M. Lemley Jr.

Theses and Dissertations

This thesis represents a continuation of the assessment of the Unified Telerobotics Architecture Project (UTAP), a proposed Air Force standard. This architecture was developed by the NASA Jet Propulsion Laboratory and the National Institute of Standards under contract to the Air Force Materiel Command Robotics and Automation Center of Excellence at Kelly AFB, Texas. Due to operating system constraints, the only UTAP implementation to date has required a separate software interface layer, adding complexity and overhead to the overall system, while reducing portability. This thesis proposes a long term effort to design and implement UTAP-compliant application software devoid of this …

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A Test-Case Based Approach To Bayesian Knowledge Base Incompleteness Detection And Correction, Louise J. Lyle Dec 1996

A Test-Case Based Approach To Bayesian Knowledge Base Incompleteness Detection And Correction, Louise J. Lyle

Theses and Dissertations

This work develops tools and techniques to identify particular Bayesian Knowledge Base (BKB) incompletenesses, and to modify the existing knowledge-base (KB) structure to correct these problems. The methodology performs manually or automatically, informing the user of either problems causing the incompleteness, or of details resulting from the automatic knowledge-base correction. The proposed methodology is designed for integration with BVAL, to augment BVAL's validation techniques.

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Collaborative Workspaces Within Distributed Virtual Environments, William D. Wells Dec 1996

Collaborative Workspaces Within Distributed Virtual Environments, William D. Wells

Theses and Dissertations

In warfare, be it a training simulation or actual combat, a commander's time is one of the most valuable and fleeting resources of a military unit. Thus, it is natural for a unit to have a plethora of personnel to analyze and filter information to the decision-maker. This dynamic exchange of ideas between analyst and commander is currently not available within the distributed interactive simulation (DIS) community. This lack of exchange limits the usefulness of the DIS experience to the commander and his troops. This thesis addresses the commander's isolation problem through the integration of a collaborative workspace within AFIT's …

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An Incremental Language Conversion Method To Convert C++ Into Ada95, Ding-Yuan Sheu Dec 1996

An Incremental Language Conversion Method To Convert C++ Into Ada95, Ding-Yuan Sheu

Theses and Dissertations

This thesis develops a methodology to incrementally convert a legacy object oriented C++ application into Ada95. Using the experience of converting a graphic application, called Remote Debriefing Tool (RDT), in the Graphics Lab of the Air Force Institute of Technology (AFIT), this effort defined a process to convert a C++ application into Ada95. The methodology consists of five phases: (1) reorganizing the software application, (2) breaking mutual dependencies, (3) creating package specifications to interface the existing C++ classes, (4) converting C++ code into Ada programs, and (5) embellishing. This methodology used the GNAT's C++ low level interface capabilities to support …

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Modeling Marine Exposure To Polychlorinated Biphenyls From Sunken Ships, Charles N. Wendt Dec 1996

Modeling Marine Exposure To Polychlorinated Biphenyls From Sunken Ships, Charles N. Wendt

Theses and Dissertations

In the past, the U.S. Navy has routinely conducted SINKing EXercises (SINKEX) for training, weapon effectiveness tests, and economic disposal of aging assets. Recent concern over polychlorinated biphenyl (PCB) chemicals aboard such target vessels has resulted in a suspension of SINKEX. The U.S. Navy has approximately 200 vessels currently requiring such disposal. Environmental legislation and health concerns preclude selling such vessels to foreign governments or scrapping. This work attempted to model the fate and transport of these PCBs by examining their transport to coastal water and their accumulation in the marine food chain. The model includes biodegradation, upwelling, partitioning of …

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Deconvolution From Wavefront Sensing Using Optimal Wavefront Estimators, Scott R. Maethner Dec 1996

Deconvolution From Wavefront Sensing Using Optimal Wavefront Estimators, Scott R. Maethner

Theses and Dissertations

A cost effective method to improve the space surveillance mission performance of United States Air Force (USAF) ground-based telescopes is investigated and improved. A minimum variance wavefront estimation technique is used to improve Deconvolution from Wavefront Sensing (DWFS), a method to mitigate the effects of atmospheric turbulence on imaging systems that does not require expensive adaptive optics. Both least-squares and minimum variance wavefront phase estimation techniques are investigated, using both Gaussian and Zernike polynomial elementary functions. Imaging simulations and established performance metrics are used to evaluate these wavefront estimation techniques for a one-meter optical telescope. Performance metrics include the average …

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Evaluating The Hazardous Materials (Hazmat) Pharmacy Among Air Force Majcoms Using Waste Reductions And Activity Indicators, W. Edward Iseman Jr. Dec 1996

Evaluating The Hazardous Materials (Hazmat) Pharmacy Among Air Force Majcoms Using Waste Reductions And Activity Indicators, W. Edward Iseman Jr.

Theses and Dissertations

The Hazardous Materials (HazMat) Pharmacy has been designed as an environmentally friendly vehicle to handle, store, dispense, track, recycle, and dispose of hazardous materials in the Air Force. This thesis effort proposed a method in which valuable feedback for the pharmacy can be obtained. Because it is still in the early stages of implementation, there has been little feedback on the pharmacy. An activity index that uses a variable most closely associated with the generation of hazardous waste in a MAJCOM is proposed. Using an aircraft maintenance related variable, like maximum take-off weight, the fluctuations in mission over time can …

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Graphical Display Of A Missile Endgame Scenario, Joseph E. Moritz Dec 1996

Graphical Display Of A Missile Endgame Scenario, Joseph E. Moritz

Theses and Dissertations

Traditionally, computer programs to model and simulate air-to-air missile endgame engagements have focused on improving the underlying probability of kill models. This focus, however, understates the benefits of current computer graphics technology for visualization and direct manipulation of missile endgame parameters and building engagement understanding through real-time, three dimensional simulation of the endgame. Our research has been to develop a versatile simulation system to display the missile endgame parameters and allow graphical interaction with these parameters. This program also allows the user to view animated engagements of previously designed endgames. The current project scope is to provide user feedback of …

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A Software Architecture For Computer Generated Forces In Complex Distributed Virtual Environments, Vincent B. Zurita Dec 1996

A Software Architecture For Computer Generated Forces In Complex Distributed Virtual Environments, Vincent B. Zurita

Theses and Dissertations

Complex Distributed Virtual Environments (DVEs) present an outstanding opportunity for the Department of Defense to train geographically separated units within a single realistic threat environment with minimal logistical considerations or safety concerns. To increase the fidelity of these simulations, minimize cost, and thereby maximize the training potential, DVEs must be populated with a realistic number of Computer Generated Forces (CGFs). These are currently expensive to design and build due to a lack of standard COF architectures. A solution to this problem is presented in the form of a CGF Architecture that is applicable to CGFs that model any weapon system. …

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A 2-D Numerical Simulation And Analysis Of A Simple Band Model For The Priz Spatial Light Modulator, Gary D. Barmore Nov 1996

A 2-D Numerical Simulation And Analysis Of A Simple Band Model For The Priz Spatial Light Modulator, Gary D. Barmore

Theses and Dissertations

This dissertation discusses the development of and analyzes the first complete, 2-D numerical simulation of the PRIZ. The simulation is based upon a simple band model of the PRIZ: a single donor, a single trap, and free electron carriers. Modeled mechanisms include photogeneration, energy level transitions, injection, drift currents, diffusion currents, photorefraction and diffraction. The model goes beyond the previous charge and field dynamics of 1-D numerical models to include optical effects, and it eliminates the oversimplifications and assumptions used in earlier mathematical models with closed solutions. Sensitivity analyses and selected simulations provide a better understanding of the dynamic imaging …

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Luminescence Study Of Ion-Implanted Gallium Nitride, Eric Silkowski Nov 1996

Luminescence Study Of Ion-Implanted Gallium Nitride, Eric Silkowski

Theses and Dissertations

Luminescence and absorption measurements were used to demonstrate the efficacy of ion implantation for introducing various classes of dopants into GaN. A wide range of implantation and annealing studies were performed with several dopant species (Ar, Zn, C, O, Si, Be, Mg, Nd, Er). Room temperature ion implantation was performed on MOCVD- and MBE-grown GaN samples at energies between 100 and 1150 keV with doses ranging from 1 x 1013 to 1 x 1015/cm-2. Conventional furnace annealing in flowing NH3 or N2 gas resulted in good implantation damage recovery at an annealing temperature …

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Nlo Waveguide "And" Switch And Method Therefor, John J. Kester, Iyad A. Dajani, Peter M. Ranon, Thomas G. Alley Sep 1996

Nlo Waveguide "And" Switch And Method Therefor, John J. Kester, Iyad A. Dajani, Peter M. Ranon, Thomas G. Alley

AFIT Patents

Method and apparatus are provided for NLO switching by first providing a phase-matched SHG grating which outputs a reinforced SHG beam only when two input beams of frequency (ω) are present in two modes of such wg. The so encoded NLO switch is operated by directing at least two input pulsed laser beams of frequency (ω) into the two modes of the wg to generate a reinforced pulsed output SHG beam and output same from the wg in an NLO switching process. The two input beams desirably have a separate pulse train and the spatial and temporal overlap of the …

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The Design Of A Financial Management Database System, Edward G. Leszynski Sep 1996

The Design Of A Financial Management Database System, Edward G. Leszynski

Theses and Dissertations

This research led to the design and development of a financial management database system for the Aeronautical Systems Center (AS C) Environmental Management (EM) Systems Program Office (SPO), which has the responsibility of managing the environmental contracts for the Government-Owned, Contractor-Operated (GOCO) plants that are owned by the Air Force. This thesis investigated the various 'development strategies' and 'methodologies' described in the Management Information Systems literature in order to devise an end-user development strategy capable of meeting the EM SPO's requirements. In addition, the information requirements, conceptual design and prototyping, and procedures phases of the System Development Life Cycle (SDLC) …

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Background Graphics: A Decision-Making Hindrance Or Enhancement?, David L. Peeler Jr. Sep 1996

Background Graphics: A Decision-Making Hindrance Or Enhancement?, David L. Peeler Jr.

Theses and Dissertations

This thesis investigated the influence, if any, of background graphics on the decision making process. Specifically the hypotheses tested the affect of background graphics on a decision makers accuracy and confidence. A literature review revealed an abundance of graphic research but little reference to the use of background graphics. Using guidelines previously created for high integrity graphics, a timed 2 x 2 factorial experimental design was developed to compare the responses to both traditional graphics and those treated with background graphics. One hundred forty-seven subjects, all employees of the United States Air Force or defense contractors were involved in the …

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Calibration Of The Checkpoint Model To The Space And Missile Systems Center (Smc) Software Database (Swdb), Karen R. Mertes Sep 1996

Calibration Of The Checkpoint Model To The Space And Missile Systems Center (Smc) Software Database (Swdb), Karen R. Mertes

Theses and Dissertations

This study analyzed the effect of calibration on the performance of the CHECKPOINT Version 2.3.1 software cost estimating model. Data used for input into the model were drawn from the FY 95 USAF SMC Software Database (SWDB) Version 2.1. A comparison was made between the model's accuracy before and after calibration. This was done using records which were not used in calibration, referred to as validation points. A comparison of calibration points, both before and after, was done in order to assess whether calibration results in more consistency within the data set used. Six measures such as magnitude of relative …

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An Exploration Of Environmental Technology Transition From The Laboratory To The Field, Michael A. Greiner Sep 1996

An Exploration Of Environmental Technology Transition From The Laboratory To The Field, Michael A. Greiner

Theses and Dissertations

Environmental policy, social factors, individual behavior, and environmental technologies are key factors in improving the current condition of the environment. The Department of Defense (DoD) is not immune to these aspects, as its actions have and will continue to impact the environment in which they conduct operations. The objective of this research is to analyze the environmental technology aspect of improving environmental conditions. Of particular interest, what barriers and bridges are encountered when an Air Force laboratory transitions environmental technologies to an end-user: operational field organization or major weapon system. The research employs a case study methodology to analyze five …

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Development Of A Standard Set Of Indicators And Metrics For Artificial Intelligence (Ai) And Expert System (Es) Software Development Efforts, Derek F. Cossey Sep 1996

Development Of A Standard Set Of Indicators And Metrics For Artificial Intelligence (Ai) And Expert System (Es) Software Development Efforts, Derek F. Cossey

Theses and Dissertations

The purpose of this research was to identify a standard set of indicators and metrics that can be used by program managers to improve their abilities to direct development efforts involving Artificial Intelligence (AI) and Expert Systems (ES). This research addresses two objectives. The first objective is to identify an appropriate set of software indicators and metrics to be used by government program offices for the management of development efforts involving software systems for AI and ES. The second objective is to demonstrate how the resources of the National Software Data and Information Repository (NSDIR) can be used in order …

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Practical Implementation Of Multiple Model Adaptive Estimation Using Neyman-Pearson Based Hypothesis Testing And Spectral Estimation Tools, Peter D. Hanlon Sep 1996

Practical Implementation Of Multiple Model Adaptive Estimation Using Neyman-Pearson Based Hypothesis Testing And Spectral Estimation Tools, Peter D. Hanlon

Theses and Dissertations

This study investigates and develops various modifications to the Multiple Model Adaptive Estimation (MMAE) algorithm. The standard MMAE uses a bank of Kalman filters, each based on a different model of the system. Each of the filters predict the system response, based on its system model, to a given input and form the residual difference between the prediction and sensor measurements of the system response. Model differences in the input matrix, output matrix, and state transition matrix, which respectively correspond to an actuator failure, sensor failure, and an incorrectly modeled flight condition for a flight control failure application, were investigated …

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Calibration Of The Softcost-R Software Cost Model To The Space And Missile Systems Center (Smc) Software Database (Swdb), Steven V. Southwell Sep 1996

Calibration Of The Softcost-R Software Cost Model To The Space And Missile Systems Center (Smc) Software Database (Swdb), Steven V. Southwell

Theses and Dissertations

The rising number and importance of Department of Defense software developments, when combined with declining defense budgets, has resulted in a critical need to accurately plan and manage software development costs and schedules. Unfortunately, the increasing size, complexity, and diversity of these software developments has made accurate estimating problematic. Uncalibrated software cost models have not generally produced reliable results due to generic default parameters and improper usage. The default parameters cannot hope to accurately represent and predict the wide variability of software efforts to which the models are being applied. However, some of the models have achieved improved accuracy by …

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Investigation Of Radio Wave Propagation In The Martian Ionosphere Utilizing Hf Sounding Techniques, Robert J. Yowell Jun 1996

Investigation Of Radio Wave Propagation In The Martian Ionosphere Utilizing Hf Sounding Techniques, Robert J. Yowell

Theses and Dissertations

This thesis presents a preliminary design of an ionospheric sounder to be carried aboard one or more of NASA's Mars Surveyor landers. Past Russian and American probes have indicated the existence of an ionosphere, but none of these missions remotely sensed this atmospheric layer from the surface. The rationale for utilizing a surface-based Martian ionospheric sounder is discussed. Based on NASA's choice of launch vehicle and power source, a low-weight, low-powered Chirp sounder using a horizontally-polarized dipole antenna is recommended for the sounder experiment. The sounder experiment should be conducted for at least one Martian year, in order to investigate …

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Characteristic Spatial Quadratures For Discrete Ordinates Neutral Particle Transport On Arbitrary Tetrahedral Meshes, Charles R. Brennan Jun 1996

Characteristic Spatial Quadratures For Discrete Ordinates Neutral Particle Transport On Arbitrary Tetrahedral Meshes, Charles R. Brennan

Theses and Dissertations

Characteristic spatial quadratures for discrete ordinates calculations on meshes of arbitrary tetrahedra are derived and tested, including the step (SC), linear (LC), and exponential (EC) characteristic quadratures and variants that assume constant distributions on cell faces. Tetrahedral meshes accurately model curved surfaces with few cells. A split cell approach subdivides tetrahedra along the streaming direction, reducing the transport to one dimension. Assumed forms of the cell source and entering flux distributions have sufficient parameters to match the zeroth and first spatial moments. These parameters are determined by analytically inverting a linear system (LC), or by numerical inversion using Newton's method …

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Design Of Gradient Index Optical Thin Films, Jeffrey J. Druessel Jun 1996

Design Of Gradient Index Optical Thin Films, Jeffrey J. Druessel

Theses and Dissertations

Gradient index thin films provide greater flexibility for the design of optical coatings than the more conventional 'layer' films. In addition, gradient index films have higher damage thresholds and better adhesion properties. This dissertation presents an enhancement to the existing inverse Fourier transform gradient index design method, and develops a new optimal design method for gradient index films using a generalized Fourier series approach. The inverse Fourier transform method is modified to include use of the phase of the index profile as a variable in rugate filter design. Use of an optimal phase function in Fourier-based filter designs reduces the …

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A Methodology For Reengineering Relational Databases To An Object-Oriented Database, Pedro A. Linhares Lima Jun 1996

A Methodology For Reengineering Relational Databases To An Object-Oriented Database, Pedro A. Linhares Lima

Theses and Dissertations

This research proposes and evaluates a methodology for reengineering a relational database to an object-oriented database. We applied this methodology to reengineering the Air Force Institute of Technology Student Information System (AFITSIS) as our test case. With this test case, we could verify the applicability of the proposed methodology, especially because AFITSIS comes from an old version of Oracle RDBMS. We had the opportunity to implement part of the object model using an object-oriented database, and we present some peculiarities encountered during this implementation. The most important result of this research is that it demonstrated that the proposed methodology can …

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Formal Transformations From Graphically-Based Object-Oriented Representations To Theory-Based Specifications, Scott A. Deloach Jun 1996

Formal Transformations From Graphically-Based Object-Oriented Representations To Theory-Based Specifications, Scott A. Deloach

Theses and Dissertations

Formal software specification has long been touted as a way to increase the quality and reliability of software; however, it remains an intricate, manually intensive activity. An alternative to using formal specifications is to use graphically-based, semi-formal specifications such as those used in many object-oriented specification methodologies. While semi-formal specifications are generally easier to develop and understand, they lack the rigor and precision of formal specification techniques. The basic premise of this investigation is that formal software specifications can be constructed using correctness preserving transformations from graphically-based object-oriented representations. In this investigation, object-oriented specifications defined using Rumbaugh's Object Modeling Technique …

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Performance Study Of A Brazilian Air Force Data Communications Network, Oswaldo Zanelli Jun 1996

Performance Study Of A Brazilian Air Force Data Communications Network, Oswaldo Zanelli

Theses and Dissertations

This thesis consists of a performance analysis of two network models using different protocols, the X.25 and Asynchronous Transfer Mode (ATM). X.25 is currently used in the data communications network infrastructure in the Brazilian Air Force. ATM is a high speed network technology. Simulations of both models were performed to compare the two technologies. This study examines the traffic load that each network can handle while still providing a good quality of service (QoS). The X.25 network model proved to have a sufficient capacity to handle the projected workload, but it presented a low QoS when a more intense traffic …

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Electrical Characterization Of Gasb Based Semiconductors For 2-4 Micrometers Diode Laser Applications, Daniel K. Johnstone Jun 1996

Electrical Characterization Of Gasb Based Semiconductors For 2-4 Micrometers Diode Laser Applications, Daniel K. Johnstone

Theses and Dissertations

Deep Level Transient Spectroscopy (DLTS) was used to characterize the band offsets and deep levels in MBE grown GaSb-based semiconductors that are used in 2-4 µm laser diode structures. One of several deep level traps found in AlxGa1-xAsySb1-y (x=0, 0.5, 0.6, 1.0) is a GaSb double acceptor trap. Progress is also made in establishing the model for the DX center in this material. The degree of compensation of the donor related DX center by GaSb affect where donors are situated, giving preference to one configuration over the many other possible configurations. One minority …

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Characterization Of Spatial And Temporal Anisotropy In Turbulent Mixing Layers Using Optical Techniques, Patrick J. Gardner May 1996

Characterization Of Spatial And Temporal Anisotropy In Turbulent Mixing Layers Using Optical Techniques, Patrick J. Gardner

Theses and Dissertations

The optical aberrations induced by mixing layers of dissimilar gases are recorded and analyzed in order to characterize the spatial and temporal properties of the flow. Laser light was propagated through a mixing layer of Helium and Nitrogen gas, having velocities of 8.5 m/sec and 1.5 m/sec, respectively. The light was propagated in a direction perpendicular to the plane of the mixing layer. The mixing layer was evaluated in two experimental regimes: free turbulent mixing, where the mixing layer spreads into the surrounding air; and channel flow, where the mixing layer is confined to a rectangular channel. The optical perturbations …

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A Generic Intelligent Architecture For Computer-Aided Training Of Procedural Knowledge, Freeman A. Kilpatrick Jr. Mar 1996

A Generic Intelligent Architecture For Computer-Aided Training Of Procedural Knowledge, Freeman A. Kilpatrick Jr.

Theses and Dissertations

Intelligent Tutoring System (ITS) development is a knowledge-intensive task, suffering from the same knowledge acquisition bottleneck that plagues most Artificial Intelligence (AI) systems. This research presents an architecture that requires knowledge only in the form of a shallow knowledge base and a simulation to produce a training system. The knowledge base provides the basic procedural knowledge while the simulation provides context. The remainder of the knowledge required for training is learned through the interaction of these components in a state-space scenario exploration process and inductive machine learning. These knowledge components are used only at the interface level, allowing the internal …

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Generalized Hidden Filter Markov Models Applied To Speaker Recognition, John M. Colombi Mar 1996

Generalized Hidden Filter Markov Models Applied To Speaker Recognition, John M. Colombi

Theses and Dissertations

Classification of time series has wide Air Force, DoD and commercial interest, from automatic target recognition systems on munitions to recognition of speakers in diverse environments. The ability to effectively model the temporal information contained in a sequence is of paramount importance. Toward this goal, this research develops theoretical extensions to a class of stochastic models and demonstrates their effectiveness on the problem of text-independent (language constrained) speaker recognition. Specifically within the hidden Markov model architecture, additional constraints are implemented which better incorporate observation correlations and context, where standard approaches fail. Two methods of modeling correlations are developed, and their …

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