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Modeling And Simulation Of Optical Characteristics Of Microelectromechanical Mirror Arrays, Peter C. Roberts
Modeling And Simulation Of Optical Characteristics Of Microelectromechanical Mirror Arrays, Peter C. Roberts
Theses and Dissertations
MEMS (Micro-Electro-Mechanical Systems) micromirror devices can be used to control the phase of a propagating light wavefront, and in particular to correct aberrations that may be present in the wavefront, due to either atmospheric turbulence or any other type of fixed or time and space varying aberrations. In order to shorten the design cycle of MEMS micromirror devices, computer software is developed to create, from MEMS micromirror device design data, a numerical model of the MEMS device. The model is then used to compute the far field diffraction pattern of a wavefront reflected from the device, and to predict the …
Student Modeling In An Intelligent Tutoring System, Jeremy E. Thompson
Student Modeling In An Intelligent Tutoring System, Jeremy E. Thompson
Theses and Dissertations
This thesis explores a new approach to modeling the student in an intelligent tutoring system (ITS), by providing a student model which learns new solutions from the student. A prototype of the new approach to ITS is demonstrated in the Euclidean geometry domain. Complete C++, CLIPS, and Tcl/Tk code listings are included in the appendices for reference. Adaptable multiple software agents were targeted for implementation, based on current literature. However, the student model is found to be maintainable without multiple software agents, while still allowing for tracking several possible solution paths when monitoring student solutions. This capability contradicts previous research …
On Unifying Time And Uncertainty: The Probabilistic Temporal Network, Joel D. Young
On Unifying Time And Uncertainty: The Probabilistic Temporal Network, Joel D. Young
Theses and Dissertations
Complex real-world systems consist of collections of interacting processes/events. These processes change over time in response to both internal and external stimuli as well as to the passage of time. Many domains such as real-time systems diagnosis, (mechanized) story understanding, planning and scheduling, and financial forecasting require the capability to model complex systems under a unified framework to deal with both time and uncertainty. Existing uncertainty representations and existing temporal models already provide rich languages for capturing uncertainty and temporal information, respectively. Unfortunately, these partial solutions have made it extremely difficult to unify time and uncertainty in a way that …
Development Of Object-Based Teleoperator Control For Unstructured Applications, Hyunki Cho
Development Of Object-Based Teleoperator Control For Unstructured Applications, Hyunki Cho
Theses and Dissertations
For multi-fingered end effectors in unstructured applications, the main issues are control in the presence of uncertainties and providing grasp stability and object manipulability. The suggested concept in this thesis is object based teleoperator control which provides an intuitive way to control the robot in terms of the grasped object and reduces the operator's conceptual constraints. The general control law is developed using a hierarchical control structure, i.e., human interface I gross motion control level in teleoperation control and fine motion control/object grasp stability in autonomous control. The gross motion control is required to provide the position/orientation of the Super …
Collaborative Workspaces Within Distributed Virtual Environments, William D. Wells
Collaborative Workspaces Within Distributed Virtual Environments, William D. Wells
Theses and Dissertations
In warfare, be it a training simulation or actual combat, a commander's time is one of the most valuable and fleeting resources of a military unit. Thus, it is natural for a unit to have a plethora of personnel to analyze and filter information to the decision-maker. This dynamic exchange of ideas between analyst and commander is currently not available within the distributed interactive simulation (DIS) community. This lack of exchange limits the usefulness of the DIS experience to the commander and his troops. This thesis addresses the commander's isolation problem through the integration of a collaborative workspace within AFIT's …
Investigation Of Ba, Bao, Sr And Sro Pulsed Laser-Induced Vapor Plumes In N2, O2, Microwave Discharged O2, And Vacuum At Low Laser Fluence, David L. Byers
Investigation Of Ba, Bao, Sr And Sro Pulsed Laser-Induced Vapor Plumes In N2, O2, Microwave Discharged O2, And Vacuum At Low Laser Fluence, David L. Byers
Theses and Dissertations
Ba, BaO, Sr and SrO were ablated by 248 nm laser pulses at fluences ranging from 270 mJ-/sq cm to 575 mJ-/sq cm in vacuum and in 25 mtorr atmospheres of N2, O2 and microwave-discharged O2. The spectral emissions of these plumes were compared for indications of ionization due to Ba or Sr collisions with each gas. The addition of a background gas increased the ion and neutral signature across the spectrum. SrO band emission was observed at 16,600-16,900/cm and possible BaO band emissions were observed in the 18,250-18,400/cm, 19,000-19700/cm and 19,800-20,000/cm regions. A screened plate ion probe was use …
Refined Genetic Algorithms For Polypeptide Structure Prediction, Charles E. Kaiser Jr.
Refined Genetic Algorithms For Polypeptide Structure Prediction, Charles E. Kaiser Jr.
Theses and Dissertations
Accurate and reliable prediction of macromolecular structures has eluded researchers for nearly 40 years. Prediction via energy minimization assumes the native conformation has the globally minimal energy potential. An exhaustive search is impossible since for molecules of normal size, the size of the search space exceeds the size of the universe. Domain knowledge sources, such as the Brookhaven PDB can be mined for constraints to limit the search space. Genetic algorithms (GAs) are stochastic, population based, search algorithms of polynomial (P) time complexity that can produce semi-optimal solutions for problems of nondeterministic polynomial (NP) time complexity such as PSP. Three …
Analysis And Design Of Standard Telerobotic Control Software, Matthew L. June
Analysis And Design Of Standard Telerobotic Control Software, Matthew L. June
Theses and Dissertations
The Robotics and Automation Center for Excellence (RACE) has defined an open telerobotics control architecture. This architecture, called the Unified Telerobotic Architecture Project (UTAP), is a proposed standard for all Air Force telerobotic systems. Implementation of UTAP will reduce the cost of robotic applications by increasing software modularity, portability, and reusability. This thesis continued the effort to prove the feasibility of UTAP. In December, 1995, 1st Lt Anchor implemented a portion of the UTAP specification on a PUMA robot. The UTAP-compliant controller exhibited some degradation in the system performance. However, the performance degradation was not fully measured. This thesis extended …
A Software Architecture For Computer Generated Forces In Complex Distributed Virtual Environments, Vincent B. Zurita
A Software Architecture For Computer Generated Forces In Complex Distributed Virtual Environments, Vincent B. Zurita
Theses and Dissertations
Complex Distributed Virtual Environments (DVEs) present an outstanding opportunity for the Department of Defense to train geographically separated units within a single realistic threat environment with minimal logistical considerations or safety concerns. To increase the fidelity of these simulations, minimize cost, and thereby maximize the training potential, DVEs must be populated with a realistic number of Computer Generated Forces (CGFs). These are currently expensive to design and build due to a lack of standard COF architectures. A solution to this problem is presented in the form of a CGF Architecture that is applicable to CGFs that model any weapon system. …
Local Effects Of Solid Rocket Motor Exhaust On Stratospheric Ozone Concentrations, Brian K. George
Local Effects Of Solid Rocket Motor Exhaust On Stratospheric Ozone Concentrations, Brian K. George
Theses and Dissertations
Solid Rocket Motors (SRMs) power the initial flight of the Space Shuttle and Titan IV rocket. During those first two minutes after liftoff, the exhaust plumes from these motors emit large quantities of chlorine compounds and alumina particles into the atmosphere. For years scientists have argued that such a large chlorine input, injected directly into the stratosphere, would photochemically react with the surrounding air to cause significant ozone depletion. To answer the question of whether SRM exhaust causes a significant ozone depletion, Version 7 data from the Total Ozone Mapping Spectrometer (TOMS) instrument was analyzed for the 30 days prior …
A Common Architecture For Simulation Viewing Over Multiple Protocol Environments, Glenn G. Jacquot
A Common Architecture For Simulation Viewing Over Multiple Protocol Environments, Glenn G. Jacquot
Theses and Dissertations
This study discusses an architecture used for displaying data results in a graphical format. This data is obtained via internet connection or from a direct connection to a battlefield simulator known as BattleSim. This architecture utilizes several graphics packages for displaying the output along with two different approaches to receiving commands from the user. Furthermore, the design was built to easily incorporate other graphics packages and communication protocols in order to increase its portability.
Graphical Display Of A Missile Endgame Scenario, Joseph E. Moritz
Graphical Display Of A Missile Endgame Scenario, Joseph E. Moritz
Theses and Dissertations
Traditionally, computer programs to model and simulate air-to-air missile endgame engagements have focused on improving the underlying probability of kill models. This focus, however, understates the benefits of current computer graphics technology for visualization and direct manipulation of missile endgame parameters and building engagement understanding through real-time, three dimensional simulation of the endgame. Our research has been to develop a versatile simulation system to display the missile endgame parameters and allow graphical interaction with these parameters. This program also allows the user to view animated engagements of previously designed endgames. The current project scope is to provide user feedback of …
A Specific Network Link And Path Likelihood Prediction Tool, Gary K. Moy
A Specific Network Link And Path Likelihood Prediction Tool, Gary K. Moy
Theses and Dissertations
Communications have always been a crucial part of any military operation. As the pace of warfare and the technological complexity of weaponry have increased, so has the need for rapid information to assess battlefield conditions. Message passing across a network of communication nodes allowed commanders to communicate with their forces. It is clear that an accurate prediction of communication usage through a network will provide commanders with useful intelligence of friendly and unfriendly activities. Providing a specific network link and path likelihood prediction tool gives strategic military commanders additional intelligence information and enables them to manage their limited resources more …
Theoretical Modeling Of Linear Absorption Coefficients In Si/Si1-Xgex Multiple Quantum Well Photodetectors, Kevin D. Greene
Theoretical Modeling Of Linear Absorption Coefficients In Si/Si1-Xgex Multiple Quantum Well Photodetectors, Kevin D. Greene
Theses and Dissertations
Si/Si1-xGex MQW Infrared Photodetectors offer the promise of normal incidence photodetection tunable over the range of 3-12 micrometers wavelength range at temperatures above 40 K. This system is attractive because the Si1-xGex offers greater compatibility with existing Si based signal processing circuitry. Band structures, momentum matrix elements and linear absorption coefficients are computed using a Luftinger-Kohn k/p analysis for Si/Si1-xGex quantum wells grown in the 110 direction. The absorption coefficient as a function of energy and wavelength is calculated by two methods: a delta function fit to intersubband transitions, and a …
Design And Prototype Of The Afit Virtual Emergency Room: A Distributed Virtual Environment For Emergency Medical Simulation, Brian W. Garcia
Design And Prototype Of The Afit Virtual Emergency Room: A Distributed Virtual Environment For Emergency Medical Simulation, Brian W. Garcia
Theses and Dissertations
Due to the increasing complexity of emergency medical care, medical staffs require increasingly sophisticated training systems. Virtual environments offer a low cost means to achieve a widely usable yet sophisticated training capability. The Defense Advanced Research Projects Agency (DARPA) has sponsored the Virtual Emergency Room (VER) project to develop a simulation system that enables emergency department personnel within level I and II emergency rooms to practice emergency medical procedures and protocols. The VER is a simulation facility that uses a distributed virtual environment architecture to enable real-time, multi-participant simulations. The potential advantages of this system include the ability to evaluate …
Dynamic Relevance Filtering In Asynchronous Transfer Mode-Based Distributed Interactive Simulation Exercises, David T. Hightower
Dynamic Relevance Filtering In Asynchronous Transfer Mode-Based Distributed Interactive Simulation Exercises, David T. Hightower
Theses and Dissertations
As Distributed Interactive Simulation (DIS) exercises continue to grow in scale, the need to support a large number of players has become apparent. The demands on the network and the simulation hosts in large exercises, though, have proved to be prohibitive, requiring significant computational overhead to filter through the information and extract what is relevant to a particular simulation. Some mechanism is needed to reduce irrelevant network traffic received by a system, while increasing the bandwidth available for the DIS exercise. Previous research efforts in this area have centered primarily on fixed geographic partitions of the battlespace to reduce the …
Molecular Articulation In Response To Interactive Atomic Forces In Docker, Todd R. Kellett
Molecular Articulation In Response To Interactive Atomic Forces In Docker, Todd R. Kellett
Theses and Dissertations
Molecular docking aids in the design of materials supporting the current and future needs of the warfighter by simulating the real-world results of combining molecules. Specifically, it supports research and development in novel non-linear optical materials for laser-hardening and other advanced optical applications. Potential uses for these materials range from personnel and optical system laser protection to holographic information displays. DOCKER, our baseline docking system, minimizes the computational overhead of the simulation by modeling the molecules as rigid objects. This simplification can cause DOCKER's solutions to disagree with the real-world results, because molecules flex as they react to one another …
Analysis Of Linkage-Friendly Genetic Algorithms, Laurence D. Merkle
Analysis Of Linkage-Friendly Genetic Algorithms, Laurence D. Merkle
Theses and Dissertations
Evolutionary algorithms (EAs) are stochastic population-based algorithms inspired by the natural processes of selection, mutation, and recombination. EAs are often employed as optimum seeking techniques. A formal framework for EAs is proposed, in which evolutionary operators are viewed as mappings from parameter spaces to spaces of random functions. Formal definitions within this framework capture the distinguishing characteristics of the classes of recombination, mutation, and selection operators. EAs which use strictly invariant selection operators and order invariant representation schemes comprise the class of linkage-friendly genetic algorithms (lfGAs). Fast messy genetic algorithms (fmGAs) are lfGAs which use binary tournament selection (BTS) with …
Algebraic Algorithm Design And Local Search, Robert P. Graham Jr.
Algebraic Algorithm Design And Local Search, Robert P. Graham Jr.
Theses and Dissertations
Formal, mathematically-based techniques promise to play an expanding role in the development and maintenance of the software on which our technological society depends. Algebraic techniques have been applied successfully to algorithm synthesis by the use of algorithm theories and design tactics, an approach pioneered in the Kestrel Interactive Development System (KIDS). An algorithm theory formally characterizes the essential components of a family of algorithms. A design tactic is a specialized procedure for recognizing in a problem specification the structures identified in an algorithm theory and then synthesizing a program. Design tactics are hard to write, however, and much of the …
Electrical Characterization Of Intrinsic And Induced Deep Level Defects In Hexagonal Sic, James D. Scofield
Electrical Characterization Of Intrinsic And Induced Deep Level Defects In Hexagonal Sic, James D. Scofield
Theses and Dissertations
Deep level defects in hexagonal SiC were studied using digital deep level transient spectroscopy (DLTS) methods over the temperature range of 100 to 800 deg K. New centers were found in bulk and epitaxial 6H-SiC with ionization energies between 0.38 to 1.3 eV, and levels from 0.2 to 0.856 eV were identified in 4H-SiC epitaxy. Direct correlation between inequivalent lattice sites was identified for energetic pairs associated with both vanadium and ion implanted Mg impurities. Nonradioative carrier capture mechanisms were studied and deep level trapping was found to proceed via lattice relaxation multi-phonon emission, indicating efficient electronic lattice coupling in …
Demonstrating Optical Aberration Correction With A Mems Micro-Mirror Device, Shaun R. Hick
Demonstrating Optical Aberration Correction With A Mems Micro-Mirror Device, Shaun R. Hick
Theses and Dissertations
This research conducted the first demonstrated use of a micro-electro-mechanical structure (MEMS) mirror array to correct a static optical aberration. A well-developed technique in adaptive optics imaging systems uses a deformable mirror to reflect the incident wave front to the imaging stage of the system. By matching the surface of the deformable mirror to the shape of the wave front phase distortion, the reflected wave front will be less aberrated before it is imaged. Typical adaptive optics systems use piezo-electric actuated deformable mirrors. This research used an electrostatically actuated, segmented mirror array, constructed by standard MEMS fabrication techniques, to investigate …
Laser-Induced Breakdown Spectroscopy On Solution Samples Using Surface Excitation, Leonard M. Berman
Laser-Induced Breakdown Spectroscopy On Solution Samples Using Surface Excitation, Leonard M. Berman
Theses and Dissertations
Laser-induced breakdown spectroscopy (LIBS) is a spectroscopic technique where output from a pulsed laser is focused onto a target in order to create an intense plasma. The optical emission is characteristic of the elements in the focal volume and can be used for elemental analysis. Research on the detection of nickel in solution in addition to solvent detection of CCl4, CHCl3, C2Cl4, and C2HCl3 has been performed. Breakdown was formed at the sample surface via a Q-switched Nd:YAG laser. Initially, operation of the laser was at 1064 nm/repetition rate of 5 Hz. Experiments …
Unfolding The High Energy Electron Flux From Crres Fluxmeter Measurements, Brian D. Mckellar
Unfolding The High Energy Electron Flux From Crres Fluxmeter Measurements, Brian D. Mckellar
Theses and Dissertations
The Combined Release and Radiation Effects Satellite (CRRES) was launched on 25 July 1990 to collect measurements in the earth's radiation belts. One instrument, the High Energy Electron Fluxmeter (HEEF), measured the flux of electrons in 10 channels with energies between 1 MeV and 10 MeV. The channel sensitivities, Ri(E), have been calibrated and partially re-calibrated. We explore the errors introduced in unfolding the electron flux spectrum from the channel measurements and the propagation and growth of calibration and measurement errors. Using numerical experimentation, we fold the responses with known spectra to obtain simulated measurements, add random measurement and calibration …
Pulse Coupled Neural Networks For The Segmentation Of Magnetic Resonance Brain Images, Shane L. Abrahamson
Pulse Coupled Neural Networks For The Segmentation Of Magnetic Resonance Brain Images, Shane L. Abrahamson
Theses and Dissertations
This research develops an automated method for segmenting Magnetic Resonance (MR) brain images based on Pulse Coupled Neural Networks (PCNN). MR brain image segmentation has proven difficult, primarily due to scanning artifacts such as interscan and intrascan intensity inhomogeneities. The method developed and presented here uses a PCNN to both filter and segment MR brain images. The technique begins by preprocessing images with a PCNN filter to reduce scanning artifacts. Images are then contrast enhanced via histogram equalization. Finally, a PCNN is used to segment the images to arrive at the final result. Modifications to the original PCNN model are …
Evaluation Of Segmentation For Bone Structures In 3d Rendering Of Ultrasound Residual Limb Images, Min C. Baker
Evaluation Of Segmentation For Bone Structures In 3d Rendering Of Ultrasound Residual Limb Images, Min C. Baker
Theses and Dissertations
Prosthetists today widely practice manual socket fitting, which produces subjective, inconsistent results. To address this problem, the Computerized Anthropometry Research and Design (CARD) Laboratory is developing a computer-aided socket design system that acquires ultrasound datasets of an amputee's residual limb, creates a 3D model, and helps identify load- bearing and pressure-relief areas. This research project focuses on providing 3D visualization of a residual limb to support the CARD Laboratory's efforts. Creating the 3D model of the skin and two bone contours requires two major steps: segmentation to identify the objects of interest and a surface tracking algorithm to generate the …
A Domain Independent Framework For Developing Knowledge Based Computer Generated Forces, James L. Benslay Jr.
A Domain Independent Framework For Developing Knowledge Based Computer Generated Forces, James L. Benslay Jr.
Theses and Dissertations
Computer Generated Forces (CGFs) are important players in Distributed Interactive Simulation (DIS) exercises. A problem with CGFs is that they do not exhibit sufficient human behaviors to make their use effective. The SOAR approach has yielded a human cognitive model that can be applied to CGFs, but this is extremely complex. The product of the research reported in this thesis is a much less complex behavioral framework for a CGF that is easy to validate, revise, and maintain. To support this, an existing, domain independent CGF architecture is discussed and applied to an experimental CGF. Techniques for modeling the knowledge …
Requirements, Design, And Development Of A Rapidly Reconfigurable, Photo-Realistic, Virtual Cockpit Prototype, Terry A. Adams
Requirements, Design, And Development Of A Rapidly Reconfigurable, Photo-Realistic, Virtual Cockpit Prototype, Terry A. Adams
Theses and Dissertations
The United States Air Force uses aircraft flight simulators for pilot training and mission rehearsal. They use a variety of simulators for this task ranging with prices ranging from $400,000 to $30,000,000. These simulators have specialized hardware that restricts reuse of their components and increases maintenance costs. Air Education and Training Command wants to reduce simulators cost and improve availability to the operational commands by supporting research in virtual reality flight simulators. This thesis looks at the development of a reconfigurable virtual cockpit in a distributed virtual environment that can be used for different aircraft as well as training scenarios. …
Inference Algorithm Performance And Selection Under Constrained Resources, Brett J. Borghetti
Inference Algorithm Performance And Selection Under Constrained Resources, Brett J. Borghetti
Theses and Dissertations
Knowing that reasoning over probabilistic networks is, in general, NP-hard, and that most reasoning environments have limited resources, we need to select algorithms that can solve a given problem as fast as possible. This thesis presents a method for predicting the relative performance of reasoning algorithms based on the domain characteristics of the target knowledge structure. Armed with this knowledge, the research shows how to choose the best algorithm to solve the problem. The effects of incompleteness of the knowledge base at the time of inference is explored, and requirements for reasoning over incompleteness are defined. Two algorithms for reasoning …
Artificial Cochlea Design Using Micro-Electro-Mechanical Systems, George C. Dalton Ii
Artificial Cochlea Design Using Micro-Electro-Mechanical Systems, George C. Dalton Ii
Theses and Dissertations
The use of Micro-Electro-Mechanical Systems (MEMS) in the design of an artificial cochlea is investigated in depth. Interdigitated finger (comb), cantilever, bridge, and mirror resonators are presented as possible devices used to implement the artificial cochlea. These resonators are demonstrated to be extremely high Q devices, capable of being tuned with a simple DC bias. This suggests a possible change to existing cochlea models that claim highly complex AC feedback as being responsible for changes in the damping of the basilar membrane. The new cochlea model presented here, using MEMS to approximate the tuning of the basilar membrane, may be …
Utilizing Bayesian Techniques For User Interface Intelligence, Robert A. Harrington
Utilizing Bayesian Techniques For User Interface Intelligence, Robert A. Harrington
Theses and Dissertations
The purpose of this research is to study the injection of an intelligent agent into modern user interface technology. This agent is intended to manage the complex interactions between the software system and the user, thus making the complexities transparent to the user. The background study will show that while interesting and promising research exists in the domain of intelligent interface agents, very little research has been published that indicates true success in representing the uncertainty involved in predicting user intent. The interface agent architecture presented in this thesis will offer one solution for solving the problem using a newly …