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Air Force Institute of Technology

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Articles 2581 - 2610 of 3052

Full-Text Articles in Physical Sciences and Mathematics

Deriving Optimal Solutions From Incomplete Knowledge Bases, Shawn A. Northrop Dec 1995

Deriving Optimal Solutions From Incomplete Knowledge Bases, Shawn A. Northrop

Theses and Dissertations

Many real world domains cannot be represented using Bayesian Networks due to the need for complete probability tables and acyclic knowledge. However, Bayesian Knowledge Bases (BKBs) are a viable method for representing these incomplete domains, but very little research has been performed on inferencing with them. This paper presents three inference engines for extracting optimal solutions from three distinct BKB subclasses: singly- connected, multiply-connected with mutually exclusive cycles, and cyclic. The singly-connected inference engine has a worst case polynomial run time. Performance improvement techniques for increasing inference engine speed are discussed, in addition to a new tool for measuring incompleteness …

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Determining The Effects Of Waste Coal Ash On Landfill Radon Levels, Richard S. Krysiak Jr. Dec 1995

Determining The Effects Of Waste Coal Ash On Landfill Radon Levels, Richard S. Krysiak Jr.

Theses and Dissertations

Coal contains trace amounts of the primary radionuclides 40K, and elements of the 4n (232Th), 4n+2 (238U), and 4n+3 (235U) series including 220Rn and 222Rn. Combustion of coal by electric power and heat plants result in concentration of noncombustible mineral matter, including most of the radionuclides, in the coal ash. The increased radiation due to the concentration of radionuclides is known as technologically enhanced natural radiation. The purpose of this research was to determine the effects of landfilled coal ash on one specific aspect of technologically enhanced natural radiation, radon levels. …

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Study Of The Long-Term Desorption Of Trichloroethylene From Clay Soils Using Infrared Spectroscopy, Mary P. Stager Dec 1995

Study Of The Long-Term Desorption Of Trichloroethylene From Clay Soils Using Infrared Spectroscopy, Mary P. Stager

Theses and Dissertations

Slow desorption of contaminants from soil presents one of the greatest challenges to modeling contaminant fate and transport and implementing effective remediation technologies. The kinetics of long-term desorption of trichloroethylene (TCE) from powdered clay soils were studied to determine the desorption rates and mechanism. Infrared absorption spectroscopy was used to monitor the concentration of TCE desorbed from contaminated flint clay for 71 hours. Observed gas phase TCE concentrations as a function of time were compared to that predicted by a one-site Langmuir desorption mechanism. The Langmuir model, with a single type of bonding site, did not account for the release …

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Characterization Of Atmospheric Turbulence Over Long Horizontal Paths Using Optical Slope Measurements, Eric E. Silbaugh Dec 1995

Characterization Of Atmospheric Turbulence Over Long Horizontal Paths Using Optical Slope Measurements, Eric E. Silbaugh

Theses and Dissertations

Atmospheric turbulence has long been recognized as one of the fundamental factors affecting optical systems operating through the atmosphere. Turbulence over vertical paths has been well characterized, both theoretically and experimentally. Much less is known about turbulence over long, horizontal paths. Perturbations of the wave front phase can be measured using a Hartmann wave front sensor (H-WFS). Theoretical expressions for the tilt removed structure function of the H-WFS slope measurements were derived and evaluated using quadrature. These slope structure functions are functions of the phase structure function. The Kolmogorov turbulence model was assumed. Simulated H-WFS slope measurements were generated using …

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Design, Fabrication And Characterization Of Micro Opto-Electro-Mechanical Systems, Darren E. Sene Dec 1995

Design, Fabrication And Characterization Of Micro Opto-Electro-Mechanical Systems, Darren E. Sene

Theses and Dissertations

Several micro-opto-electro-mechanical structures were designed using the Multi-User MEMS Process (MUMPS). Specific design techniques were investigated for improving the capabilities of elevating flip up structures. The integration of several flip up microoptical structures into a microoptical system was explored with emphasis on the development of a microinterferometer. The thermal effects on the Modulus of Elasticity were determined by detecting the resonant frequency for a square Flexure Beam Micromirror Device. The resonance of the device was found to match theory to within 0.1 % and the Modulus of Elasticity was found to decrease by 0.041 GPa/K from 290 to 450 K. …

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Evaluation Of The Air Force Installation Restoration Advisory System, Dale M. Fox Dec 1995

Evaluation Of The Air Force Installation Restoration Advisory System, Dale M. Fox

Theses and Dissertations

This research is intended to evaluate the Air Force's Installation Restoration Advisory System Workstation software and documentation. Groundwater modeling is the biggest aid to Air Force Installation Restoration decision makers in making their conclusions about what to do with their hazardous waste sites where the groundwater is contaminated. The Advisory System aids the user in determining if a site poses a potential problem, and if so assists the user in selecting an appropriate groundwater transport model. The decision of what type of model is most suitable is based upon the user's conceptual site model and the decision is made by …

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Objectism 3.0: A Software Architecture For The Development Of Portable Visual Simulation Applications, Shawn M. Hannan Dec 1995

Objectism 3.0: A Software Architecture For The Development Of Portable Visual Simulation Applications, Shawn M. Hannan

Theses and Dissertations

A visual simulation software architecture is a reusable design for visual simulation applications. This thesis effort was the third stage in an ongoing refinement of such an architecture, named ObjectSim. The primary goals of this stage were to improve the architecture by eliminating its dependence on two platform-specific graphics libraries (named GL and Performer, from Silicon Graphics, Inc.), and to examine the potential for expanding the architecture to accommodate distributed simulations. The effort resulted in a new version of the architecture which allows the development of visual simulation applications which take full advantage of the aforementioned libraries without calling those …

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Evaluating The Feasibility Of Sequential Indicator Simulation In Reproducing Spatial Connectivity In A Heterogeneous Transmissivity Field, D. Duane Kenyon Dec 1995

Evaluating The Feasibility Of Sequential Indicator Simulation In Reproducing Spatial Connectivity In A Heterogeneous Transmissivity Field, D. Duane Kenyon

Theses and Dissertations

A Non-Parametric estimation technique was used to simulate realizations of a heterogeneous transmissivity field based upon sampled values from three different sampling scenarios. These realizations were compared to output from a parametric estimation technique with respect to truth as defined by an exhaustive data set of 6,000 transmissivity values. Estimated transmissivity fields were then used as input into a flow model from which fields of heads and specific discharges were obtained and compared. Given the financial limitations imposed upon the number and quality of samples reasonably available, Sequential Indicator Simulation, a non-parametric technique, was shown to be of considerable value …

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The Effect Of Meteorological Data Averaging Times On Plume Concentrations From Explosive Ordnance Disposal Open Burning Operations, Ida L. Widmann Dec 1995

The Effect Of Meteorological Data Averaging Times On Plume Concentrations From Explosive Ordnance Disposal Open Burning Operations, Ida L. Widmann

Theses and Dissertations

Explosive Ordnance Disposal (EOD) Open Burning (OB) operations are performed to treat and dispose of unserviceable munitions in the Department of Defense (DOD) inventory. Air pollution modeling of OB operations is an Environmental Protection Agency requirement for permit issuance at OB sites. Specific OB regulation is still in its infancy; therefore, establishment of OB modeling techniques is still in the early stages. This thesis effort sought to develop a computer model, based upon the Gaussian Puff Equation. The model varies from standard plume modeling practices by not making the assumption that the wind direction, wind speed and turbulence are uniform …

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The Relationship Between Environmental Attitudes And Environmental Behaviors Among Air Force Members, Daniel T. Holt Dec 1995

The Relationship Between Environmental Attitudes And Environmental Behaviors Among Air Force Members, Daniel T. Holt

Theses and Dissertations

A questionnaire was distributed to nearly 2,000 randomly selected active duty Air Force members assigned to locations throughout the continental United States. The survey was designed to determine the extent to which Air Force members expressed support for environmental issues. In addition, the survey measured how frequently Air Force members engaged in specific behaviors that were deemed environmentally protective. Although the Air Force members expressed relatively strong support for environmental issues, they only occasionally engaged in activities that contribute to the preservation or protection of the environment. Correlation analysis revealed that the pro-environmental attitudes were positively linked to the environmentally …

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Design And Evaluation Of Standard Telerobotic Control Software, Kevin P. Anchor Dec 1995

Design And Evaluation Of Standard Telerobotic Control Software, Kevin P. Anchor

Theses and Dissertations

This thesis represents the first implementation of a proposed Air Force standard telerobotic control architecture. This architecture was developed by the NASA Jet Propulsion Laboratory and the National Institute of Standards and Technology under contract to the Air Force Materiel Command Robotics and Automation Center of Excellence (RACE) as the Unified Telerobotics Architecture Project (UTAP). The AFIT Robotics and Automation Applications Group (RAAG) Lab B facility computational structure was redesigned to be compliant with the UTAP architecture. This thesis shows that the UTAP specification to be implementable. However, if the underlying operating system does not support generic message passing, an …

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Reducing Lag In Virtual Displays Using Multiple Model Adaptive Estimation, David W. Kyger Dec 1995

Reducing Lag In Virtual Displays Using Multiple Model Adaptive Estimation, David W. Kyger

Theses and Dissertations

Multiple Model Adaptive Estimation is an effective method for reducing lag in virtual environment displays. Lag in displays (the time from head motion to the appearance of the proper image on the display) is a significant detriment to realism in virtual environments. Increasing the speed of the computers which control the virtual display is not a final answer. No matter how fast the processors work, there will always be demands to do more. Predicting angular head positions (look-angles) can reduce the lag by allowing the computer to calculate the appropriate scene before it is needed on the display. Single predictors …

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Maximum Likelihood Estimation Of Wave Front Slopes Using A Hartmann-Type Sensor, Scott A. Sallberg Dec 1995

Maximum Likelihood Estimation Of Wave Front Slopes Using A Hartmann-Type Sensor, Scott A. Sallberg

Theses and Dissertations

Current methods for estimating the wave front slope at the pupil of a telescope equipped with a Hartmann-type wave front sensor (H-WFS) are based on a simple centroid calculation of the intensity distributions (spots) recorded in each subaperture of the H-WFS. The centroid method does not include any knowledge concerning correlation properties of the slopes over the subapertures or the amount of light collected by the telescope and diverted to the H-WFS for wave front reconstruction purposes. This thesis devises a maximum likelihood (ML) estimation of the spot centroids by incorporating statistical knowledge of the spot shifts. The light level …

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Computer-Aided Diagnosis Of Mammographic Masses, William E. Polakowski Dec 1995

Computer-Aided Diagnosis Of Mammographic Masses, William E. Polakowski

Theses and Dissertations

A new Model-Based Vision algorithm was developed to find possibly cancerous regions of interest (ROIs) in digitized mammograms and to correctly identify the malignant masses. This work has shown a sensitivity of 92 percent for locating malignant ROIs. The database contained 272 images (12 bit, 1OO microns) with 36 malignant and 53 benign mass images. Of the 53 biopsied benign cases, 74 percent were correctly classified. The Focus of Attention (segmentation) Module algorithm used a physiologically motivated Difference of Gaussians (DoG) filter to highlight mass-like regions in the mammogram. The Index Module labeled the regions by their hypothesized class: large …

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Atmospheric Transport And Diffusion Modeling Of Rocket Exhaust, Chad A. Burel Dec 1995

Atmospheric Transport And Diffusion Modeling Of Rocket Exhaust, Chad A. Burel

Theses and Dissertations

Space launches at Vandenberg Air Force Base (VAFB) and the Cape Canaveral Air Station (CCAS) produce exhaust from the solid rocket boosters and liquid hypergolic fuels containing several toxic substances including hydrogen chloride and hydrazine. In order to estimate the health risk that would be imposed upon the public by proposed launches, range safety officials rely on the Rocket Exhaust Effluent Diffusion Model to predict where the exhaust chemicals will go after the launch and how strong the concentrations will be. The original REEDM program averaged the meteorological parameters (wind speed, wind direction, shear, etc.) across the entire mixing level …

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The Application Of Hybridized Genetic Algorithms To The Protein Folding Problem, Robert L. Gaulke Dec 1995

The Application Of Hybridized Genetic Algorithms To The Protein Folding Problem, Robert L. Gaulke

Theses and Dissertations

The protein folding problem consists of attempting to determine the native conformation of a protein given its primary structure. This study examines various methods of hybridizing a genetic algorithm implementation in order to minimize an energy function and predict the conformation (structure) of Met-enkephalin. Genetic Algorithms are semi-optimal algorithms designed to explore and exploit a search space. The genetic algorithm uses selection, recombination, and mutation operators on populations of strings which represent possible solutions to the given problem. One step in solving the protein folding problem is the design of efficient energy minimization techniques. A conjugate gradient minimization technique is …

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Effects Of Neutron Radiation On Resonant Cavity Light-Emitting Diodes, Daniel S. Hinkel Dec 1995

Effects Of Neutron Radiation On Resonant Cavity Light-Emitting Diodes, Daniel S. Hinkel

Theses and Dissertations

Resonant Cavity Light Emitting Diodes (RCLEDs) were irradiated in Ohio State University's nuclear reactor to determine the effects of Neutron displacement damage. The RCLEDs were characterized both before and after irradiation by their current versus voltage curves (I-V curves) and external light power versus current curves (L-I curves). The I-V curves showed an increase in the "knee voltage" at a neutron fluence of 1.45x1017 neutrons/cm2. Logarithmic decreases in external light power and differential quantum efficiency were observed. Significant decreases in external light power were observed at neutron fluences greater than 5.1x1013 neutrons/cm2. Equations were developed to …

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Photoluminescence And Electroluminescence Of Erbium And Neodymium Implanted Semiconductors, James R. Hunter Dec 1995

Photoluminescence And Electroluminescence Of Erbium And Neodymium Implanted Semiconductors, James R. Hunter

Theses and Dissertations

Low temperature photoluminescence (PL) and electroluminescence (EL) measurements were used to study the excitation of erbium- and neodymium-implanted GaAs and AlxGa1-xAs (x=0. 1, 0.3) pn-junctions. The rare-earth (RE) emissions were investigated as a function of ion dose, aluminum mole fraction, laser excitation power, and applied forward bias voltage for the implanted samples. Low temperature PL was also measured from Er doped silicon grown by the metalorganic chemical vapor-phase deposition (MOCVD) method using various growth parameters.. The MOCVD-grown Si samples were studied as a function of metalorganic source temperature, silane (SiH4) flow, growth time, and …

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Analysis And Interpretation Of Ion Data Associated With Neutral Gas Releases In The Earth's Ionosphere, Timothy M. Shadid Dec 1995

Analysis And Interpretation Of Ion Data Associated With Neutral Gas Releases In The Earth's Ionosphere, Timothy M. Shadid

Theses and Dissertations

Barium and strontium release experiments were conducted throughout 1991 from the Combined Release and Radiation Effects Satellite (CRRES) to study both natural and man-made disturbances in the earth's ionosphere. A mass spectrometer on the spacecraft counted the Ba and Sr ions as the cloud expanded. In this study, data from the G-1 (in sunlight) and G-11b (in darkness) releases were modeled to understand the source of the ion signals. The model reproduced the Ba+ sun data well assuming photoionization (τ = 28 s) was the primary ionization mechanism. However, it was not able to account for the remaining ion …

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Semantic Interpretation Of An Artificial Neural Network, Stanley D. Kinderknecht Dec 1995

Semantic Interpretation Of An Artificial Neural Network, Stanley D. Kinderknecht

Theses and Dissertations

Recent advances in machine learning theory have opened the door for applications to many difficult problem domains. One area that has achieved great success for stock market analysis/prediction is artificial neural networks. However, knowledge embedded in the neural network is not easily translated into symbolic form. Recent research, exploring the viability of merging artificial neural networks with traditional rule-based expert systems, has achieved limited success. In particular, extracting production (IF.. THEN) rules from a trained neural net based on connection weights provides a valid set of rules only when neuron outputs are close to 0 or 1 (e.g. the output …

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Geostatistical Analysis Of Hydraulic Conductivity In Heterogeneous Aquifers, Craig S. Biondo Dec 1995

Geostatistical Analysis Of Hydraulic Conductivity In Heterogeneous Aquifers, Craig S. Biondo

Theses and Dissertations

Observations of the spatial variability of hydraulic conductivity of the heterogeneous alluvial aquifer at Columbus Air Force Base in Mississippi are analyzed using parametric geostatistical approaches. Field studies have revealed that the heterogeneity of the aquifer hydraulic conductivity field controls the movement and dispersion of groundwater solutes. Therefore, a means of quantifying spatial variability is essential for the application of flow and solute transport models to practical problems. Application of these models requires a large number of hydraulic conductivity measurements. Geostatistical analysis and kriging estimation procedures assist in providing these large numbers of values when sampling designs have provided sparse …

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Decision Support Model To Optimize Site Characterization Activities Taken In Compliance With The Comprehensive Environmental Response Compensation And Liability Act, Daniel J. Clairmont Dec 1995

Decision Support Model To Optimize Site Characterization Activities Taken In Compliance With The Comprehensive Environmental Response Compensation And Liability Act, Daniel J. Clairmont

Theses and Dissertations

One of the most frequently cited reasons for the slow and costly progress of Superfund cleanups is the remedial investigation and feasibility study process (RI/FS). After each phase of the RI/FS process there are several possible alternatives that may be chosen. This research developed decision support models to help decision makers choose between the feasible alternatives at five different decision points during site characterization activities. The models make recommendations on how to deal with any particular chemical based on the risk posed by that chemical. The models assume that the value of characterizing the site further is a reduction in …

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A System Dynamics Approach To Modelling The Degradation Of Biochemical Oxygen Demand In A Constructed Wetland Receiving Stormwater Runoff, Leslie A. Mudgett Dec 1995

A System Dynamics Approach To Modelling The Degradation Of Biochemical Oxygen Demand In A Constructed Wetland Receiving Stormwater Runoff, Leslie A. Mudgett

Theses and Dissertations

The objective of this research was to develop a tool to aid the Air Force Environmental Manager in the identification of the design parameters of a constructed wetland system that may be optimized to provide a desired biochemical oxygen demand (BOD) removal efficiency during the treatment of Air Force stormwater runoff. The objective is achieved through the development and use of a system dynamics model which simulates the hydrological functions of a constructed wetland as well as the processes within the wetland responsible for degradation of BOD. Based on literature review, the primary mechanism responsible for the degradation of BOD …

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A Comparison Of Response Surface Methodology And A One-Factor-At-A-Time Approach As Calibration Techniques For The Bioplume-Ii Simulation Model Of Contaminant Biodegradation, Benjamin Shuman Dec 1995

A Comparison Of Response Surface Methodology And A One-Factor-At-A-Time Approach As Calibration Techniques For The Bioplume-Ii Simulation Model Of Contaminant Biodegradation, Benjamin Shuman

Theses and Dissertations

This thesis compared Response Surface Methodology (RSM) to the one-factor-at-a-time approach for calibrating the Bioplume-II simulation model of contaminant biodegradation. The MADE-2 data set from Columbus Air Force Base, Mississippi was used. The one-factor-at-a-time approach reduced the root-mean-squared (RMS) error for the flow to 0.921225 feet in a total of 36 runs of Bioplume-II. The RSM approach reduced the error criterion to 0.918875 in a total of 47 runs. The one-factor-at-a-time approach was unable to reduce the error below 67.1831 parts per billion (ppb) after 21 runs. The RSM approach reduced the RMS error to 67.0327 ppb after 47 runs. …

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Two-Wavelength Neodymium Based Lasers, Scott H. Mccracken Dec 1995

Two-Wavelength Neodymium Based Lasers, Scott H. Mccracken

Theses and Dissertations

A dual wavelength Q switched laser cavity has been successfully designed and assembled to evaluate the new neodymium (Nd) based materials. Initial characterization has been achieved for Nd:YAG and Nd:YLF. The results indicate that for a fixed pulse repetition frequency, the delay time can be used to adjust the relative energy between the 1.06 and 1.32 micrometer pulses. Any deficiency in the performance of one transition can be made up by performance in the other simply by changing the relative amount of time the population inversion is allowed to build up for each pulse. The best performance was obtained using …

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Steady-State Kinetics Of Br(2P1/2) Yields Co2(101) Electronic-To-Vibrational Energy Transfer Laser System, Stephen J. Karis Nov 1995

Steady-State Kinetics Of Br(2P1/2) Yields Co2(101) Electronic-To-Vibrational Energy Transfer Laser System, Stephen J. Karis

Theses and Dissertations

Steady state photolysis experiments were conducted to gain information relevant to the construction of a continuous wave electronic to vibrational pumped infrared laser. An Ar+ laser =488 µm) was used to produce the electronically excited state Br(2P1/2) (Br*) via photolysis of molecular bromine. Energy was then transferred to the near resonant vibrational state CO2(101) (CO2) via the collisional quenching of Br* by CO2. The dependence of the 2.71 µm Br* and 4.3 µm CO2 emissions on CO2 pressure was measured, as well as …

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Collisional Dynamics Of The Rubidium 52P Levels, Matthew D. Rotondaro Sep 1995

Collisional Dynamics Of The Rubidium 52P Levels, Matthew D. Rotondaro

Theses and Dissertations

The collisional dynamics of the 52P levels in rubidium has been examined using steady-state laser absorption and spectrally-resolved laser induced fluorescence techniques. State-to-state cross-sections for energy transfer between Zeeman split levels ranged from 16-248 °A2 for collisions with nitrogen and rare gases. These energy transfer cross-sections exhibit a significant dependence on (J,mj) state and certain symmetry relationships are demonstrated. A sub-Doppler spectrum of the Zeeman split levels indicating the isotopic shift in the D1 line of 106 ± 35 was obtained using laser saturation spectroscopy.

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A Comparative Evaluation Of Voice Versus Keypad Input For Manipulating Electronic Technical Data For Flight Line Maintenance Technicians, David A. Chapman, James R. Simmons Sep 1995

A Comparative Evaluation Of Voice Versus Keypad Input For Manipulating Electronic Technical Data For Flight Line Maintenance Technicians, David A. Chapman, James R. Simmons

Theses and Dissertations

Interactive Electronic Technical Manuals will soon become a requirement for aircraft maintenance technicians. An important aspect in their development is the selection of an input device that will enhance, rather than impede, technician performance. The purpose of this thesis was to evaluate two types of input devices that can he used: a voice recognition input and a keypad input. Studies to date have evaluated the superiority of digital data over paper data, and advantages of using a Head Mounted Display Device over a flat screen laptop computer. No research has evaluated the input device. An experiment was conducted to determine …

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Calibration Of The Software Architecture Sizing And Estimation Tool (Saset), Carl D. Vegas Sep 1995

Calibration Of The Software Architecture Sizing And Estimation Tool (Saset), Carl D. Vegas

Theses and Dissertations

This study attempted to analyze the effect of calibration on the performance of the SASET computer software cost estimating model. Data used for input into the model were drawn from the most current USAF SMC Software Database (SWDB). Once all the records to be used for analysis were identified, the DBMS-Calibration tool (which is part of SASET) was used to perform regression analysis on the relationship between program size (measured in SLOC) and the effort required to develop the program (measured in man-months). Productivity information reported from this tool was then input into equations used to calculate the Productivity Calibration …

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Calibration Of The System Evaluation And Estimation Of Resources Software Estimation Model (Seer-Sem) For The Air Force Space And Missile Systems Center (Smc), Kolin D. Rathmann Sep 1995

Calibration Of The System Evaluation And Estimation Of Resources Software Estimation Model (Seer-Sem) For The Air Force Space And Missile Systems Center (Smc), Kolin D. Rathmann

Theses and Dissertations

This study examined whether calibration of the SEER-SEM impacted the effort estimates generated by the model for software developments- A historical database was provided by the Space and Missile System's Center Los Angeles, and used as the model's input data. The data was stratified into four usable platforms, military ground command and-control, military ground signal processing, military specification avionics, and military mobile. Each platform's data sets were split, the majority of points for calibration of the model, and the rest for model validation. The accuracy of SEER to this particular data set is limited, yet the model did respond to …

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