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Articles 1 - 28 of 28
Full-Text Articles in Physical Sciences and Mathematics
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.
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 …
Temporal Influence On Awareness, Don E. Hill
Temporal Influence On Awareness, Don E. Hill
Theses and Dissertations
Grossberg's Motion Oriented Contrast Filter (MOC) was extensively analyzed (7). The output from the filter's "global motion" neuronal layer was compared to a noncausal post-processing filter developed by AFIT. Both filters were shown to incorporate a weighted, noncausal temporal range of input data in processed output. The global motion framework was then implemented using a physiologically motivated pulsed neural model - the Pulse Coupled Neural Network (PCNN). By incorporating both spatial and temporal data, the PCNN was shown to exhibit a common visual illusion, apparent motion. The existence of a physiological temporal processing range was further investigated through implementation of …
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 …
Transforming Algebraically-Based Object Models Into A Canonical Form For Design Refinement, Charles G. Beem
Transforming Algebraically-Based Object Models Into A Canonical Form For Design Refinement, Charles G. Beem
Theses and Dissertations
The understandability of object-oriented design techniques and the rigor of formal methods have improved the state of software development; however, both ideas have limitations. Object-oriented techniques, which are semi-formal, can still result in incorrect designs, while formal methods are complex and require an extensive mathematical background. The two approaches can be coupled, however, to produce designs that are both understandable and verifiable, and to produce executable code. This research proposes an approach where object-oriented models are first represented algebraically in a formal specification language such as LARCH and then transformed into a canonical form suitable for design refinement. In the …
Semantic Interpretation Of An Artificial Neural Network, Stanley D. Kinderknecht
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 …
Deriving Optimal Solutions From Incomplete Knowledge Bases, Shawn A. Northrop
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 …
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 …
The Application Of Hybridized Genetic Algorithms To The Protein Folding Problem, Robert L. Gaulke
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 …
An Object-Oriented, Formal Methods Approach To Organizational Process Modeling, Vincent S. Hibdon
An Object-Oriented, Formal Methods Approach To Organizational Process Modeling, Vincent S. Hibdon
Theses and Dissertations
This document presents a methodology for developing an organizational process model which is based on the principles of object oriented design and formal software engineering methods. The methodology begins with the development of an object oriented Rumbaugh model (27). The Rumbaugh model is then formally specified in Z (Zed) schemas. Finally, the Z specifications are translated into an executable model in the Software Refinery Environment(TM). This model is described based on the AF wing domain and developed in this domain. The proposed methodology is then shown to produce a very general model which is extendable across almost any domain. The …
Design And Evaluation Of Standard Telerobotic Control Software, Kevin P. Anchor
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 …
Neural Network Analysis Of Chemical Compounds In Nonrebreathing Fisher-344 Rat Breath, Robert E. Sackett Jr.
Neural Network Analysis Of Chemical Compounds In Nonrebreathing Fisher-344 Rat Breath, Robert E. Sackett Jr.
Theses and Dissertations
This research applies statistical and artificial neural network analysis to data obtained from measurement of organic compounds in the breath of a Fisher-344 rat. The Research Triangle Institute (RTI) developed a breath collection system for use with rats in order to collect and determine volatile organic compounds (VOCs) exhaled. The RTI study tested the hypothesis that VOCs, including endogenous compounds, in breath can serve as markers to exposure to various chemical compounds such as drugs, pesticides, or carcinogens normally foreign to living organisms. From a comparative analysis of chromatograms, it was concluded that the administration of carbon tetrachloride dramatically altered …
Dynamic Transfer Of Control Between Manned And Unmanned Simulation Actors, Neal W. Schneider
Dynamic Transfer Of Control Between Manned And Unmanned Simulation Actors, Neal W. Schneider
Theses and Dissertations
This thesis continues the ongoing research at the Air Force Institute of Technology's Virtual Environments Laboratory in the area of distributed simulation. As the relevance and interest of interactive simulation as a training medium continues to grow, there is a pressing need to provide more realistic and numerous intelligent autonomous agents for simulations. As those autonomous agents mature and become more realistic, the need exists to be able to handle individual agents by taking control of them and operating them as manned agents at certain points within the simulation. The author started with a protocol proposed in a working draft …
Air Force Materiel Command (Afmc) Modeling, Simulation, And Analysis (Ms&A) Interactive Database, Timothy J. Wagner
Air Force Materiel Command (Afmc) Modeling, Simulation, And Analysis (Ms&A) Interactive Database, Timothy J. Wagner
Theses and Dissertations
This study develops a high level, unifying taxonomy for Modeling, Simulation, and Analysis (MS&A) products for the Air Force Materiel Command (AFMC). AFMC is concerned that limited resources are being expended on duplicative MS&A efforts. No mechanism exists that would confirm or deny this concern, so it was suggested that a database could be developed to catalog and track AFMC's MS&A inventory. First, it was necessary to determine the information that a decision maker needs to select a suitable MS&A product. Potential traits and characteristics were identified through review of current regulatory guidance, interviews with MS&A users, and a study …
Calibration Of The Software Architecture Sizing And Estimation Tool (Saset), Carl D. Vegas
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 …
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
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 …
A Comparative Evaluation Of Voice Versus Keypad Input For Manipulating Electronic Technical Data For Flight Line Maintenance Technicians, David A. Chapman, James R. Simmons
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 …
The Mathematics Of Measuring Capabilities Of Artificial Neural Networks, Martha A. Carter
The Mathematics Of Measuring Capabilities Of Artificial Neural Networks, Martha A. Carter
Theses and Dissertations
Researchers rely on the mathematics of Vapnik and Chervonenkis to capture quantitatively the capabilities of specific artificial neural network (ANN) architectures. The quantifier is known as the V-C dimension, and is defined on functions or sets. Its value is the largest cardinality 1 of a set of vectors in Rd such that there is at least one set of vectors of cardinality 1 such that all dichotomies of that set into two sets can be implemented by the function or set. Stated another way, the V-C dimension of a set of functions is the largest cardinality of a set, such …
Biomedical Data Interpolation For 3-D Visualization, Ming-Chung Chen
Biomedical Data Interpolation For 3-D Visualization, Ming-Chung Chen
Theses and Dissertations
Medical imaging devices that produce three-dimensional data usually produce the data in the form of image slices. In such images, the resolution in z direction is lower than in x and y directions. Before extracting and displaying objects in such images, an interpolated 3-D gray-scale volume image can be generated via image interpolation techniques to fill in the missing information. The subject of this thesis is the applying three different interpolation techniques to generate intermediate slices and comparing their qualities. The three interpolation techniques are linear interpolation, cubic spline interpolation, and Fourier interpolation. We also apply the CT image matching …
Optimal Mixed-Norm Control Synthesis For Discrete-Time Linear Systems, David R. Jacques
Optimal Mixed-Norm Control Synthesis For Discrete-Time Linear Systems, David R. Jacques
Theses and Dissertations
A mixed-norm approach to control synthesis for discrete time linear systems is developed. Specifically, the problem of minimizing the H2 norm of a transfer function, subject to a combination of ℓ1 and-or H∞ norm constraints on dissimilar but related transfer functions is considered. The uniqueness of the optimal solution is shown, and numerical methods for approximating the optimal solution to within arbitrary accuracy are developed. These methods generally result in high order compensators which can not be implemented in most practical applications. In response to this, a numerical method is developed which solves for suboptimal solutions of …
Physiologically-Based Pharmacokinetic Modeling Of Skin Absorption Using Dermal Subcompartments, Richard L. Bookout Jr.
Physiologically-Based Pharmacokinetic Modeling Of Skin Absorption Using Dermal Subcompartments, Richard L. Bookout Jr.
Theses and Dissertations
Dermal penetration of chemicals and drugs is important to both toxicologists and pharmacologists. Drug developers try to enhance and environmental professionals try to limit penetration of chemicals through the skin. Both can use predictive biologically-based mathematical models to assist in understanding the processes involved. When these models are based on physiological and biochemical parameters which can be measured in the laboratory, they can be extremely useful. Appropriately validated models based on first principles can be predictive of human exposures when the processes involved are adequately understood. In this thesis we develop four new physiologically-based pharmacokinetic (PBPK) models to predict blood …
Teaching Accommodation Task Skills: From Human Demonstration To Robot Control Via Artificial Neural Networks, Paul V. Whalen
Teaching Accommodation Task Skills: From Human Demonstration To Robot Control Via Artificial Neural Networks, Paul V. Whalen
Theses and Dissertations
A simple edge-mating task, performed automatically by accommodation control, was used to study the feasibility of using data collected during a human demonstration to train an artificial neural network (ANN) to control a common robot manipulator to complete similar tasks. The 2-dimensional (planar) edge-mating task which aligns a peg normal to a fiat table served as the basis for the investigation. A simple multi-layered perceptron (MLP) ANN with a single hidden layer and linear output nodes was trained using the back-propagation algorithm with momentum. The inputs to the ANN were the planar components of the contact force between the peg …
Analysis Of Heads-Up Display Quickening Versus Handling Qualities, Gary M. Konnert
Analysis Of Heads-Up Display Quickening Versus Handling Qualities, Gary M. Konnert
Theses and Dissertations
This study investigated an analytical means of selecting the quickening time constant for the standardized Heads-Up Display flight path marker. The theoretically determined time constant allowed a faster, less resource intensive means of selecting the quickening time constant. The theoretically best time constant for pilot-aircraft handling qualities was equal to the airframe pitch attitude high frequency zero time constant, Tθ2. Flight test indicated an empirical, more labor intensive method yielded better handling qualities, even though paper analysis indicated the theoretical method was better. The theoretically determined time constant gave slightly lower handling qualities. but was less costly to …
Formal Foundations For The Specification Of Software Architecture, Mark J. Gerken
Formal Foundations For The Specification Of Software Architecture, Mark J. Gerken
Theses and Dissertations
This investigation establishes a formal foundation for software architecture that allows for the specification of large, non-trivial software systems using well founded, consistency preserving construction techniques. Two fundamental problems were addressed: how to define and express architectures formally using the concept of theories, and how architecture theories can be practically applied in specification construction. The initial stages of this investigation sought to establish a formal, mathematical relationship between functional specifications of behavior and specifications defining system structure. Experimental results lead to the conclusion that architectures defining the structure of functional operations can be defined using functional logic, but more complex …
The Effect Of Repeatedly Sampling An Embedded Metamodel On The Simulation Response, John Kent Patterson
The Effect Of Repeatedly Sampling An Embedded Metamodel On The Simulation Response, John Kent Patterson
Theses and Dissertations
This study investigated the effect on simulation output of repeatedly sampling an embedded metamodel. A metamodel is said to be embedded within a simulation if it is used to replace a submodule of that simulation. Replacing a deterministic module with an embedded deterministic metamodel poses no apparent mathematical problems. However, using a deterministic metamodel to replace a stochastic simulation component could require additional corrective actions. This research was performed in two phases. The first phase dealt with a set of tandem queues. It was shown that as each queue was sequentially replaced with a metamodel, the total system variance was …
Nonlinear Time Series Analysis, James A. Stewart
Nonlinear Time Series Analysis, James A. Stewart
Theses and Dissertations
This thesis applies neural network feature selection techniques to multivariate time series data to improve prediction of a target time series. Two approaches to feature selection are used. First, a subset enumeration method is used to determine which financial indicators are most useful for aiding in prediction of the S&P 500 futures daily price. The candidate indicators evaluated include RSI, Stochastics and several moving averages. Results indicate that the Stochastics and RSI indicators result in better prediction results than the moving averages. The second approach to feature selection is calculation of individual saliency metrics. A new decision boundary-based individual saliency …
Analysis And Extension Of Model-Based Software Executives, Keith E. Lewis
Analysis And Extension Of Model-Based Software Executives, Keith E. Lewis
Theses and Dissertations
This research developed a comprehensive description of the simulation environment of Architect, a domain-oriented application composition system being developed at the Air Force Institute of Technology to explore new software engineering technologies. The description combines information from several previous research efforts and Architect's source code into a single, comprehensive document. A critical evaluation of the simulation environment was also performed, identifying improvements and modifications that enhance Architecture's application execution capabilities by reducing complexity and execution time. The analysis was then taken one step further and presented extensions to the current simulation environment. The extensions included investigating the feasibility of mixed-mode …
Visage: Improving The Ballistic Vulnerability Modeling And Analysis Process, Brett F. Grimes
Visage: Improving The Ballistic Vulnerability Modeling And Analysis Process, Brett F. Grimes
Theses and Dissertations
The purpose of this thesis was to improve the process of modeling and analyzing ballistic vulnerability data. This was accomplished by addressing two of the more urgent needs of vulnerability analysts; the ability to display fault tree data and to edit target descriptions. A vulnerability data visualization program called VISAGE was modified to meet these needs. VISAGE was originally created to preview static shotline plots and subsequently grew into a full-featured visualization package for vulnerability target descriptions and analyses data. The next logical step in the programs evolution was to include the needed editing and fault tree display capabilities. The …