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Articles 1 - 30 of 253
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A Neural Network Approach To The Prediction And Confidence Assignation Of Nonlinear Time Series Classifications, Erin S. Heim
A Neural Network Approach To The Prediction And Confidence Assignation Of Nonlinear Time Series Classifications, Erin S. Heim
Theses and Dissertations
This thesis uses multiple layer perceptrons (MLP) neural networks and Kohonen clustering networks to predict and assign confidence to nonlinear time series classifications. The nonlinear time series used for analysis is the Standard and Poor's 100 (S&P 100) index. The target prediction is classification of the daily index change. Financial indicators were evaluated to determine the most useful combination of features for input into the networks. After evaluation it was determined that net changes in the index over time and three short-term indicators result in better accuracy. A back-propagation trained MLP neural network was then trained with these features to …
Vehicle Thermal Control With A Variable Area Inlet, Thomas R. Layne
Vehicle Thermal Control With A Variable Area Inlet, Thomas R. Layne
Theses and Dissertations
This study developed a variable area inlet and controller that regulated the temperature of an electrical component with ram air. The intent of the variable area inlet was to reduce vehicle drag by eliminating inefficiencies associated with component cooling and fixed area inlets. These inefficiencies arise from vehicles moving at varying speeds through varying air temperatures. The hardware model consisted of an electrical component mounted inside a right-circular cylindrical duct. The variable area inlet, mounted in the front of the duct, consisted of a butterfly valve that was actuated by a stepper controller acted on the feedback signal of a …
Decision Support Model For Municipal Solid Waste Management At Department Of Defense Installations, John F. Muratore
Decision Support Model For Municipal Solid Waste Management At Department Of Defense Installations, John F. Muratore
Theses and Dissertations
This research focuses on the development of a decision support model to identify the preferred strategy for managing municipal solid waste using the principles of decision analysis theory. The model provides an effective decision making tool to evaluate and compare different municipal solid waste management strategies. The users of this model, the Environmental Manager or decision maker at a given installation, can enter installation-specific waste stream characteristics, treatment and disposal costs, and material buy-back prices to determine the expected value for various alternative strategies. The strategy having the greatest expected value is considered the preferred alternative. In calculating the expected …
Design And Analysis Of Parallel Hierarchical Battlefield Simulation, Conrad P. Masshardt
Design And Analysis Of Parallel Hierarchical Battlefield Simulation, Conrad P. Masshardt
Theses and Dissertations
The purpose of this research is to determine if hierarchically partitioning a discrete event battlefield simulation reduces runtime and, if reduction exists, to characterize the run time reduction given any particular partition configuration. A hierarchical discrete event simulation of a main battle tank was constructed. Implementations were built for both a single processor and a multiprocessing machine. The implementations used the Message Passing Interface to increase portability to other parallel and distributed configurations. Three test cases were generated and run on three parallel and distributed environments, a network of Sun SparcStation 20's, a Silicon Graphics Power Challenge, and a Paragon …
A Solid Surface From Which To Explore: The Executive Summary As The Frontispiece Of A Technical Hyperdocument, Alicia M. Williams
A Solid Surface From Which To Explore: The Executive Summary As The Frontispiece Of A Technical Hyperdocument, Alicia M. Williams
Theses and Dissertations
This research analyzes the purpose and organization of a well-written executive summary, reviews the characteristics of hypermedia, and compares the strengths and weaknesses of a typical executive summary published originally on paper and now under consideration for transition to hypermedia in order to determine which elements of an executive summary are essential before effective transition to hypermedia. The executive summary of a technical report is a stand-alone description of what was done, how it was done, what the results were, why they matter, and where further information is found in the report body. Executive summaries have a wider audience than …
A Comparison Of Loose And Tight Gps/Ins Integration Using Real Ins And Gps Data, Warren H. Nuibe
A Comparison Of Loose And Tight Gps/Ins Integration Using Real Ins And Gps Data, Warren H. Nuibe
Theses and Dissertations
An extended Kalman filter (EKE) is used to combine the information obtained from a Global Positioning System (GPS) receiver and an Inertial Navigation System (INS) to provide a navigation solution. This research compares the results of a tightly-coupled GPS/INS integrated system with a loosely-coupled integrated system, using real world data. A fair comparison is accomplished by using the same sets of data, and keeping the integration structures as close as possible. Both integrations are feedforward and have the same error states in the navigation Kalman filters. Differences between the two, such as navigation solutions and tuning values, are shown in …
Probabilistic Knowledge Base Validation, Howard T. Gleason
Probabilistic Knowledge Base Validation, Howard T. Gleason
Theses and Dissertations
Our work develops a new methodology and tool for the validation of probabilistic knowledge bases throughout their lifecycle. The methodology minimizes user interaction by automatically modifying incorrect knowledge; only the occurrence of incomplete knowledge involves interaction. These gains are realized by combining and modifying techniques borrowed from rule-based and artificial neural network validation strategies. The presented methodology is demonstrated through BVAL, which is designed for a new knowledge representation, the Bayesian Knowledge Base. This knowledge representation accommodates incomplete knowledge while remaining firmly grounded in probability theory.
An Analysis Of 1994 Air Force Toxic Release Inventory Reporting, Brian A. Pollock
An Analysis Of 1994 Air Force Toxic Release Inventory Reporting, Brian A. Pollock
Theses and Dissertations
The purpose of this research is to analyze the Air Force's 1994 Toxic Release Inventory data. Statistical tests were used to meet the following research objectives: (1) review the CY 94 data to determine which chemicals were most often reported and which bases and major commands had the most releases in terms of the number of chemicals reported and the amount of chemicals reported and (2) investigate factors which could influence the reporting status of a facility. An analysis of the TRI data showed that dichloromethane was the chemical released in the largest amount while methyl ethyl ketone was the …
Exmis: An Expert System For The Autonomous Onboard Command System (Aocs), Kevin D. Benedict
Exmis: An Expert System For The Autonomous Onboard Command System (Aocs), Kevin D. Benedict
Theses and Dissertations
The primary objective of this study is the creation of a prototype expert system called EXMIS (EXpert MIssile System) that performs the flight termination logic sequence of the Autonomous Onboard Command System (AOCS). The AOCS is a proposed system that would take the "man-in-the-loop" out of the self-destruct decision making process and place the entire decision on the launch vehicle. Through the use of a six degree of freedom trajectory program called BOOST, simulated flight data for four different flight scenarios is obtained. The launch vehicle selected for the simulations is the Peacekeeper ICBM. EXMIS is developed using an expert …
Experimental Investigation Of A Supersonic Boundary Layer Including Favorable Pressure Gradient Effects, Joel J. Luker
Experimental Investigation Of A Supersonic Boundary Layer Including Favorable Pressure Gradient Effects, Joel J. Luker
Theses and Dissertations
This study used advanced laser Doppler velocimetry techniques to measure the turbulence intensities and Reynolds shear stresses in Mach 2.8 turbulent flat plate and Mach 2.9 favorable pressure gradient (FPG) boundary layers. The FPG was generated using a convex curved wall and had a strength of ß = 0.1, where ß is Clauser's equilibrium parameter. The maximum magnitude of the 'extra' strain rates normalized by the main strain rates was 0.1, which meant the FPG was considered to be a strong pressure gradient. The fiat plate results indicated that the LDV procedures used in this experiment prevented angular biasing of …
The Relationship Between Environmental Attitudes And Environmental Behaviors Among Air Force Members, Daniel T. Holt
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 …
Improving The Morse Intercept Operator's Audio Display, Jesse M. Washburn
Improving The Morse Intercept Operator's Audio Display, Jesse M. Washburn
Theses and Dissertations
This thesis improves the audio display for multiple Morse communications. Factors considered to improve the audio display are frequency of source, volume level of source, and methods of unmasking. The best frequency and volume level of a Morse source is 500 Hz at 70 dB sound pressure level (spi). Two types of masking are researched: frequency masking and expectation driven masking. Experiments showed by amplifying high pitched sources the effects of frequency masking are minimized. Other methods to compensate for frequency masking are 3-D sound and the placement of a source out of phase between the ears. Morse code recognition …
Space Object Identification Using Spatio-Temporal Pattern Recognition, Gary W. Brandstrom
Space Object Identification Using Spatio-Temporal Pattern Recognition, Gary W. Brandstrom
Theses and Dissertations
This thesis is part of a research effort to automate the task of characterizing space objects or satellites based on a sequence of images. The goal is to detect space object anomalies. Two algorithms are considered - the feature space trajectory neural network (FST NN) and hidden Markov model (HMM) classifier. The FST NN was first presented by Leonard Neiberg and David P. Casasent in 1994 as a target identification tool. Kenneth H. Fielding and Dennis W. Ruck recently applied the hidden Markov model classifier to a 3D moving light display identification problem and a target recognition problem, using time …
Three Dimensional Localization Of Lesions From Digitized Mammograms, Amy L. Magnus
Three Dimensional Localization Of Lesions From Digitized Mammograms, Amy L. Magnus
Theses and Dissertations
This thesis describes new algorithms to localize regions-of-interests (ROIs) three dimensionally from a pair of digitized mammograms. This work is intended to add a layer of sophistication to computer aided diagnosis by putting to use the fixed and measurable parameters of mammographic imaging. The fixed parameters are the source to film orientation and the podium-image distance. Measurable parameters are the rotation angle of the x-ray tube from the horizontal and the compression depth (the distance from compression paddle to contact podium distance) at the time of imaging. As an additional benefit, three dimensional localization algorithms alleviate the confusion radiologists may …
Objectism 3.0: A Software Architecture For The Development Of Portable Visual Simulation Applications, Shawn M. Hannan
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 …
Model Of Chlorocarbon (Cfc-12) Chemisorption On Solid Rocket Motor Alumina Exhaust Particles, Gary E. Lund
Model Of Chlorocarbon (Cfc-12) Chemisorption On Solid Rocket Motor Alumina Exhaust Particles, Gary E. Lund
Theses and Dissertations
Solid Rocket (SRMs) that power Titan IV rockets and Space Shuttles, exhaust large quantities of potentially ozone damaging pollutants directly into the stratosphere, while in powered flight. In the past, studies on potential stratospheric impact of the exhaust products from aluminum/ammonium perchlorate based SRMs have focused on the effect of gaseous HCl from SRMs on the stratosphere. Until recently, the impact of heterogeneous chemistry on stratospheric ozone was believed to be relatively insignificant. This research investigates the potential heterogeneous process of CFC-12 dissociative chemisorption on alumina surfaces and the release of reactive halogen species known to destroy ozone. Through a …
In Situ Warming And Soil Venting To Enhance The Biodegradation Of Jp-4 In Cold Climates: A Critical Study And Analysis, Ricky D. Cox
In Situ Warming And Soil Venting To Enhance The Biodegradation Of Jp-4 In Cold Climates: A Critical Study And Analysis, Ricky D. Cox
Theses and Dissertations
Numerous bioremediation projects have proven effective in accelerating contaminant biodegradation by injecting oxygen into the vadose zone with a technique called bioventing. In cold climates, bioremediation is limited to the summer when soil temperatures are sufficient to support microbial growth. Laboratory studies directly correlate increased biodegradation rates with temperature. By raising soil temperatures, in situ jet fuel remediation can be accelerated which was shown by a bioventing project conducted in 1991 at Eielson AFB, Alaska, where three soil warming techniques were used. Two methods actively warmed the soil - warm water circulation and heat tape; the other passively warmed the …
A Comparison Of Remediation Priorities Developed By The Defense Priority Model, The Relative Risk Evaluation Method, And A Quantitative Risk Assessment Approach, David M. Hunter
Theses and Dissertations
The Superfund, established by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, seriously underestimated both the number of severely contaminated sites and the associated cleanup cost. The magnitude of projected cleanup costs, coupled with shrinking federal budgets, necessitated the development and use of risk-based prioritization models among some federal agencies. Among these tools, the DOD prioritization models are meant to give priority to sites posing the greatest threat to human health. Their failure to properly rank sites could incorrectly shift the focus from those that pose substantial risk to sites of lesser risk. The DOD site ranking …
Perceptions Of Coherence And Usability In Environmental Impact Documents As Functions Of Visual And Linguistic Cues, Ronald B. Shankland
Perceptions Of Coherence And Usability In Environmental Impact Documents As Functions Of Visual And Linguistic Cues, Ronald B. Shankland
Theses and Dissertations
Environmental impact statements (EISs) are prepared so decision makers can consider the potential environmental impacts of a proposed action. The National Environmental Policy Act mandates that EISs be clear, concise, and to the point so decision makers and the lay public can understand them, however, several authors assert these documents do not meet this requirement. To examine the usability of EISs, a 1994 AFIT GEEM student, Jill A. Easterly, altered visual and linguistic discourse elements in portions of sample ElSs and then a pool of readers answered objective questions about passages from these EISs. Easterly measured the effect of presence …
Modified Model For Transient Response Of Mrna Synthesis To Magnetic Field Exposure, Timothy W. Crosnoe
Modified Model For Transient Response Of Mrna Synthesis To Magnetic Field Exposure, Timothy W. Crosnoe
Theses and Dissertations
It is a well-known fact that high frequency, or radio frequency, radiation can be directly harmful to biological tissue. The radiation frequencies to which humans are most exposed, however, are the extremely low frequencies, or ELFs. To date there has been no definitive measure for predicting the ability of low frequency electromagnetic radiation to cause adverse biological effects. Two specific measures, average magnetic field and kinetic index, have been used in studies to determine if they are useful predictors of adverse effects, specifically leukemia. Unfortunately, both have shown only marginal results. This thesis analyzed and improved the kinetic index measure …
Velocity Determination For An Inverted Pseudolite Navigation Reference System, Jeffrey M. Hebert
Velocity Determination For An Inverted Pseudolite Navigation Reference System, Jeffrey M. Hebert
Theses and Dissertations
As navigation systems continue to improve in performance and features, the Air Force must develop better Navigation Reference Systems (NRS) to keep pace with technology. Specifically, with the advent of enhanced, integrated Global Positioning System (GPS) and Inertial Navigation System (INS) navigators, emphasis is placed on the measuring performance in the presence of GPS jamming. To meet these needs, a new NRS, dubbed the Sub-Meter Accuracy Reference System (SARS), is being developed by the 746th Test Squadron, Holloman AFB, New Mexico. SARS uses a unique, inverted GPS pseudolite positioning system to determine a reference trajectory. This research investigates two post …
Reducing Lag In Virtual Displays Using Multiple Model Adaptive Estimation, David W. Kyger
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 …
Design And Analysis Of A Navigation System Using The Federated Filter, Stephen J. Delory
Design And Analysis Of A Navigation System Using The Federated Filter, Stephen J. Delory
Theses and Dissertations
The purpose of this paper was to design and analyse a federated filter design, to be used for retrofit of an Embedded GPS/INS (EGI) navigation unit into an existing Kalman filter-based air navigation system. A design was selected and simulations were conducted in the Distributed Kalman Filter Simulation software (DKFSIM). As well, a centralized Kalman filter design was simulated under identical conditions for comparison purposes. The federated filter was shown to be a feasible design, with accuracy in position and velocity very close to centralized Kalman filter values. The federated filter design also showed some attractive fault detection and isolation …
Analysis Of Gravity-Gradient Satellite Attitude Inversion, Jules-Francois D. Desamours
Analysis Of Gravity-Gradient Satellite Attitude Inversion, Jules-Francois D. Desamours
Theses and Dissertations
The purpose of this research is to understand and describe the process by which the 1986 Polar BEAR gravity- gradient research satellite of John Hopkins University/Applied Physics Laboratory achieved an orbital attitude correction (re-inversion) from an inverted orientation through the utilization of its momentum wheel. Understanding this process provides an analytical foundation from which a universal attitude inversion process for other gravity-gradient satellites with similar anomalous motions may be sought and developed. The equations of motion for a gravity-gradient satellite with a momentum wheel are derived and implemented in FORTRAN for simulation of the dynamics of the spacecraft. Several re-inversion …
The Comparative Effectiveness Of Computer-Mediated Communication Supplemented Satellite Distance Education And Traditional Face-To-Face Education, Megan C. Block
Theses and Dissertations
Satellite distance education delivery typically has one main drawback -- limited student-to-student and student-to-instructor interaction. Telecommunications technology, more specifically computer-mediated communication (CMC), has made it possible for educational institutions to overcome this drawback. This research examines the comparative effectiveness of CMC supplemented satellite distance education delivery and traditional face-to-face education delivery. The three dependent variables that were measured to compare the two educational delivery methods included: performance, interaction, and attitude outcomes. Pre- and post-course instruments were administered in a non-equivalent quasi-experimental design to students enrolled in an Air Force Institute of Technology's School of Systems and Logistics software engineering Professional …
An Investigation Of A Usaf Information Resource Management Community World Wide Web Site, Kristin A. Waldner
An Investigation Of A Usaf Information Resource Management Community World Wide Web Site, Kristin A. Waldner
Theses and Dissertations
This research project investigated establishing a World Wide Web (WWW) site dedicated to the United States Air Force Information Resource Management (IRM) community. The project determined guidelines for successful, appropriate format and content for such a site. To discover what benefits the IRM community might achieve, the project explored those benefits achieved or expected to be achieved by the business community and by government agencies with established WWW sites. The project also attempted to define an average profile of active duty IRM community Internet and WWW users. The above objectives were accomplished through a literature review and through the use …
An Investigation Of The Appropriateness Of Computer-Based Instruction To The Royal Australian Air Force Ciscon Mustering, Linda M. New
An Investigation Of The Appropriateness Of Computer-Based Instruction To The Royal Australian Air Force Ciscon Mustering, Linda M. New
Theses and Dissertations
Currently, the Royal Australian Air Force (RAAF) uses traditional methods of training for all of its personnel, including the newly formed Communications and Information Systems Controllers (CISCON) mustering. The formation of this mustering and the concurrent formation on every RAAF base of a Base Information Systems Centre (BISC) brought to light training needs that were not being met. Using many different forms of stimulation to activate learning, computer-based instruction (CBI), in particular multimedia, represents an alternative method of presenting training.This research investigated the applicability of CBI to the RAAF by matching its features with the training needs of the CISCONs …
Thermo-Mechanical Fatigue Behavior Of Cross-Ply Ceramic Matrix Composite Under Tension-Tension Loading, Dana G. Allen
Thermo-Mechanical Fatigue Behavior Of Cross-Ply Ceramic Matrix Composite Under Tension-Tension Loading, Dana G. Allen
Theses and Dissertations
The purpose of this study was to investigate the combined effect of cyclic temperature and loading on the fatigue life of a ceramic matrix composite with a cross ply lay-up. The material used in this study was a potassium borosilicate glass (BSG) doped magnesium aluminosilicate (MAS) cordierite matrix reinforced with Nicalon (silicon carbide, SiC) fibers in a [0/90]4s lay-up. Thermomechanical fatigue (TMF) tests were performed with a period of 180 seconds/cycle, or 0.00556 Hz, and a triangular wave-form. The temperature was cycled between 566°C and l093°C, and the stress levels varied between 60 MPa and 145 MPa. All tests …
Experimental Investigation Of A Supersonic Turbulent Boundary Layer With Adverse Pressure Gradient, Chad S. Hale
Experimental Investigation Of A Supersonic Turbulent Boundary Layer With Adverse Pressure Gradient, Chad S. Hale
Theses and Dissertations
Laser Doppler Velocimetry (LDV) measurements were made to quantify the effect of adverse pressure gradient on the compressible turbulent flow structure in a Mach 2.9 boundary layer (Re/m= 1.75 x 107). Measurements included profiles of 2-D mean velocities, turbulence intensities, Reynolds shear stresses, intermittency, flatness and skewness. In addition, mean strain rates were also measured. The boundary layer measurements were acquired for both flat plate and compression ramp models. LDV measurements were made at two locations on the compression ramp model at 68 cm and 71 cm downstream of the nozzle throat. At these locations, Β …
An Experimental Investigation Of A Sting-Mounted Finite Circulation Control Wing, Lorenzo C. Bradley Iii
An Experimental Investigation Of A Sting-Mounted Finite Circulation Control Wing, Lorenzo C. Bradley Iii
Theses and Dissertations
This study investigated the lift, drag and pitching moment performance of a circulation control wing in the AFIT 5-ft wind tunnel. The experimental wing model was a 20 percent thick, 8.5 percent camber, partial elliptical cross-section, single blowing slot, rectangular planform wing. The aspect ratios tested were 3.99, 3.77 and 3.75. The variables in the investigation included the slot blowing rate and model configuration. The model was modified by adding a leading edge nose droop, a trailing edge splitter plate and wing tip fences to improve flow at the leading edge, reduce separation effects, and encourage attached flow on the …