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Air Force Institute of Technology

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Articles 2371 - 2400 of 2678

Full-Text Articles in Physical Sciences and Mathematics

Effects Of Photon Noise On Unconstrained Minimization Techniques For Iterative Blind Deconvolution, Derek K. Davis Dec 1994

Effects Of Photon Noise On Unconstrained Minimization Techniques For Iterative Blind Deconvolution, Derek K. Davis

Theses and Dissertations

In recent years, imaging through atmospheric turbulence has interested military scientists seeking to improve optical surveillance of satellites. Adaptive optics was a step toward achieving diffraction-limited resolution from ground-based telescopes. Unfortunately, adaptive optics only partially compensate for atmospheric blurring, therefore post processing of images is required. Processing methods in use today require knowledge of the impulse response of the optical system to reconstruct imagery, but this information is seldom known. This thesis looks at a new metal of processing compensated imagery, called blind deconvolution, which assumes very little or no a priori information about the impulse response. In particular, this …

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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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Embedology And Neural Estimation For Time Series Prediction, Robert E. Garza Dec 1994

Embedology And Neural Estimation For Time Series Prediction, Robert E. Garza

Theses and Dissertations

Time series prediction has widespread application, ranging from predicting the stock market to trying to predict future locations of scud missiles. Recent work by Sauer and Casdagli has developed into the embedology theorem, which sets forth the procedures for state space manipulation and reconstruction for time series prediction. This includes embedding the time series into a higher dimensional space in order to form an attractor, a structure defined by the embedded vectors. Embedology is combined with neural technologies in an effort to create a more accurate prediction algorithm. These algorithms consist of embedology, neural networks, Euclidean space nearest neighbors, and …

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A General Object Model Transformation System, John P. Mullaney Dec 1994

A General Object Model Transformation System, John P. Mullaney

Theses and Dissertations

Cecil and Fullenkamp developed a program that transforms knowledge captured in an object-model in one environment into a different object-model in a different environment. This program worked well for the intended purpose, but if one of the object-models is replaced by a different object-model then this transformation program has to be re-engineered. As the object-modeling paradigm becomes more prevalent, many systems are experiencing this problem. The primary goal of this research was to determine what reusable knowledge could be extracted from these types of program and used to build a general object-model transformer that generalizes such transformation programs. Toward this …

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Minimizing The Impact Of Synchronization Overhead In Parallel Discrete Event Simulations, Andrew C. Walton Dec 1994

Minimizing The Impact Of Synchronization Overhead In Parallel Discrete Event Simulations, Andrew C. Walton

Theses and Dissertations

A Parallel Discrete Event Simulation Coprocessor was designed for conservative synchronization protocols and was implemented in software using some of a parallel computer's nodes to act as coprocessors. The coprocessor was designed to offload synchronization overhead and next event queue management from the nodes running the simulation. The coprocessor was designed to accelerate simulations based on the Simulation Protocol Evaluation on a Concurrent Testbed with ReUsable Modules (SPECTRUM) environment. The research was conducted in three steps: the SPECTRUM environment was ported from an Intel iPSC-2 to an Intel Paragon XP-S, the coprocessor was designed and the simulations were timed, with …

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The Re-Engineering Of The Air Force Institute Of Technology Student Information System, Douglas J. Wu Dec 1994

The Re-Engineering Of The Air Force Institute Of Technology Student Information System, Douglas J. Wu

Theses and Dissertations

This research describes the design and implementation issues associated with re-engineering the Air Force Institute of Technology Student Information System (AFITSIS). Currently, AFITSIS executes on aging relational database technology and has unfriendly user interface mechanisms. The two research objectives met were to research current AFITSIS requirements, design, and implementation, and use object-oriented methods to design an alternative implementation based on proposed object database management system standards. This research explores how AFITSIS performance and capabilities might be enhanced by taking advantage of new object-oriented software engineering techniques. One of the primary benefits of this research is a detailed object modeling technique …

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Image Perception Wavelet Simulation And Enhancement For The Visually Impaired, Lemuel Ray Myers Jr. Dec 1994

Image Perception Wavelet Simulation And Enhancement For The Visually Impaired, Lemuel Ray Myers Jr.

Theses and Dissertations

This research delves into the area of image enhancement for the visually impaired. Binocular macular degeneration a visual impairment, affects many Americans; since this condition could not be corrected with conventional glasses the literature suggested using an enhancement system which used a pre-emphasis algorithm to enhance the input image for output to the observer. The work of Dr. Eli Peli, a pioneer in the field of image enhancement, is examine and reproduced. Since his work concentrated mainly on frequency analysis of images, the bulk of this research involves using discrete wavelet analysis to augment that work. A biorthogonal wavelet set …

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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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The Excitation Mechanism Of Praseodymium-Doped Semiconductors, Paul L. Thee Jun 1994

The Excitation Mechanism Of Praseodymium-Doped Semiconductors, Paul L. Thee

Theses and Dissertations

This study on praseodymium Pr luminescence in AlxGa1-xAs was conducted to enhance the understanding of the excitation mechanism. Pr was implanted at 390 keV with doses from 5 x 1012 to 5 x 1013 sq cm into AlxGa1-xAs x0.0 to 0.50 wafers which were annealed using the rapid thermal annealing RTA method. Low temperature photoluminescence PL was conducted using an Ar-ion laser and Ge detector. PL emissions of Pr from all hosts include peaks near 1.3 and 1.6 µm which are assigned to the intra-4f transitions of 1G4 yielding 3H5 …

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A Diffraction-Based Model Of Anisoplanatism Effects In Adaptive Optic Systems, Steven E. Troxel Jun 1994

A Diffraction-Based Model Of Anisoplanatism Effects In Adaptive Optic Systems, Steven E. Troxel

Theses and Dissertations

This dissertation presents a new model for computing the angle dependent performance measures of an adaptive-optics system. By incorporating diffraction caused by the index-of-refraction variations of the atmosphere, the phase and amplitude fluctuations of the propagating wave are computed. New theory is presented, that uses the diffraction-based propagation model to yield optical transfer function (OTF) expressions that are more accurate as compared to current theory that neglects diffraction. An evaluation method for calculating the OTF is presented that utilizes a layered atmospheric model and normalized OTF expressions. The diffraction model is also used to present the first OTF signal-to-noise ratio …

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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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Searching For Plans Using A Hierarchy Of Learned Macros And Selective Reuse, Douglas E. Dyer Jun 1994

Searching For Plans Using A Hierarchy Of Learned Macros And Selective Reuse, Douglas E. Dyer

Theses and Dissertations

This research presents a new approach to improving the performance of a macro planner: selective reuse. In macro planning, reuse can result in poorer performance than when planning with only primitive operators, a phenomenon that has been called the utility problem. The utility problem arises because the benefits of reuse are outweighed by the cost of retrieving a macro to reuse and the cost of searching through the larger search space caused by considering reuse candidates. Selective reuse contains the expansion of the search space by limiting the number of reuse candidates considered and limits the search required by considering …

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Noise Reduction For Speech Enhancement Using Non-Linear Wavelet Processing, Hassan Dehmani Jun 1994

Noise Reduction For Speech Enhancement Using Non-Linear Wavelet Processing, Hassan Dehmani

Theses and Dissertations

The problem of speech enhancement presents many obstacles in the speech processing field. This thesis develops several speech de-noising systems that can be used in the time, fourier, and wavelet domains. We present two thresholding techniques soft and hard. The application of these thresholding techniques to noisy speech data is discussed. The combination of both wavelets and the Fourier domains with noisy phase restoration proves to yield the best results in terms of intelligibility. Informal listening tests were conducted in order to compare the effects and differences between the speech de-noising systems.

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