Engineering Commons^™

An Object-Oriented Discrete-Event Simulation System For Hierarchical Parallel Simulations, Kenneth W. Stauffer

Theses and Dissertations

The purpose of this research is to design and implement an object-oriented discrete-event simulation system which supports hierarchically constructed players in a parallel or distributed environment. This system design considers modularity and portability so additional modules may be implemented to experiment with new algorithms for both partitioning and synchronization. A simulation system which meets these requirements was partially implemented on an eight-node Intel Hypercube in C. A desired goal was to maintain the functionality of the existing BattleSim application. Test cases used measure the performance and correct operation of the new simulation architecture using a BattleSim subclass. Test results prove …

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 …

Equalization Of A Non-Linear Phase Of A Low-Pass Filter, Rabih Khodor

Dissertations and Theses

In practice, an IIR filter can distort the information content of the signal because of its inherent non-linear phase characteristics introduced through the design of the filter. If the the receiver of the signal is the human ear, e.g., when a speech or music signal is to be processed, phase distortion is quite tolerable. But, in other applications it can be rejected as phase characteristics is required to be fairly linear. Applications of this type include data transmission, where the signal is to be interpreted by digital hardware, and image processing, where the signal is used to reconstruct an image …

An Asic Power Analysis System For Digital Cmos Design, Du Van Nguyen

Dissertations and Theses

Consumers demand for products with ever-increasing functionality, performance, and longer battery life is making low power a critical factor in most system designs. Lower-power designs are less expensive to produce, more reliable, and cost less to operate - factors which create a real competitive advantage. As a result, ASIC designers are demanding better ways to analyze the power of their designs.

In this thesis, an ASIC Power Analysis System (APAS) is developed. APAS is an interactive simulation-based power analysis tool. Using a non-intrusive design technique, APAS can dynamically "snap on" to an existing simulation environment. APAS currently supports three ASIC …

The Multiple Pool Migrating Worker Paradigm : A Distributed System Framework And Model, Cynthia Ann Stanley

Dissertations and Theses

A network of workstations (NOW) can provide an inexpensive and effective distributed processing platform. The purpose of this thesis is two-fold, providing a methodology for distributed computing on a NOW first, and providing a model to predict and monitor performance second. The Multiple Pool-Migrating Worker (MPMW) paradigm uses multiple job pools to divide up tasks and migrating workers to balance the work load. The MPMW paradigm is a quick and efficient way of implementing problems using distributed processing without extensive knowledge of parallel programming. A model describing the MPMW paradigm is developed using queuing theory and Mean Value Analysis techniques. …

Improvements In A Hybrid Stochastic/Deterministic Method For Transient Three-Dimensional Neutron Transport, Charles L. Bentley

Doctoral Dissertations

This research develops an improved methodology (and corresponding code) for solving the time-dependent, three-dimensional Boltzmann Transport Equation with explicit representation of delayed neutrons. These improvements are incorporated in a modified version of the code TDKENO, entitled TDKENO-M. Specifically, these improvements are:

1. Incorporate the improved quasistatic methodology into an existing quasistatic framework. Specifically, include the flux shape derivative in the fixed source term instead of being neglected. Also, compute the point kinetics parameters deterministically by their inner product definitions.

2. Incorporate a hierarchy of three different integration time intervals for the numerical solution of the coupled set of ordinary differential …

Burst Pressure Prediction Of Filament Wound Composite Pressure Vessels Using Acoustic Emission, Marcus Elwood Fisher

Master's Theses - Daytona Beach

This research demonstrates how acoustic emission (AE) data from flaw growth activity can be used to predict burst pressures in filament wound composite pressure vessels. Acoustic emission data were taken during hydroproof testing for a set of eleven ASTM standard 5.75 inch diameter fiberglass/epoxy bottles. Amplitude distributions were created using only the AE data up to 25% of the expected burst pressure to simulate low level proof loadings (thereby avoiding damage to the bottles). The bottles were tested at three different temperatures -- 32°F, 70°F, and 110°F - and hydroproofed using two different pressurization schemes and two transducer configurations. Moreover, …

Elastic-Plastic Behavior And Limit Load Analysis Of Pipe Elbows Under In-Plane Bending And Internal Pressure, Mohab Ahmed Shalaby

Archived Theses and Dissertations

No abstract provided.

Iswe: A Case Study Of Technology Transfer, Michael P.J. Benfield

Honors Capstone Projects and Theses

No abstract provided.

Perceptual Fidelity For Digital Color Imagery, Curtis E. Martin

Theses and Dissertations

The problem of measuring the fidelity of digital color images in a manner that corresponds to human perceptual assessments is addressed. Experiments are performed to validate human visual system (HVS) models, which provide access to a 'perceptual space' in which visual distortions may be measured, and then a model is proposed for assessing the perceptual fidelity of digital color image. Color Mach bands are produced in the first experiment, demonstrating that, as in the brightness channel, low spatial frequency attenuation occurs in the chromatic channels of the HVS. In the second experiment, a correlation between the chromatic channels of the …

Using Kriging To Interpolate Spatially Distributed Volumetric Medical Data, Stephen M. Matechik

Theses and Dissertations

Routine cases in diagnostic radiology require the interpolation of volumetric medical imaging data sets. Inaccurate renditions of interpolated volumes can lead to the misdiagnosis of a patient's condition. It is therefore essential that interpolated modality space estimates accurately portray patient space. Kriging is investigated in this research to interpolate medical imaging volumes. Kriging requires data to be spatially distributed. Therefore, magnetic resonance imaging (MRI) data is shown to exhibit spatially regionalized characteristics such that it can be modeled using regionalized variables and subsequently be interpolated using kriging. A comprehensive, automated, three-dimensional structural analysis of the MRI data is accomplished to …

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 …

Application Of A Finite-Volume Time-Domain Maxwell Equation Solver To Three-Dimensional Objects, Frederick G. Harmon

Theses and Dissertations

Concurrent engineering approaches for the disciplines of computational fluid dynamics (CFD) and electromagnetics (CEM) are necessary for designing future high-performance, low-observable aircraft. A characteristic-based finite-volume time-domain (FVTD) computational algorithm, developed for CFD and now applied to CEM, is implemented to analyze the radar cross section (RCS) of two three-dimensional objects, the ogive and cone-sphere. The FVTD formulation implements a Monotone Upstream-Centered Scheme for Conservation Laws (MUSCL) algorithm for the flux evaluation and a Runge-Kutta multi-stage scheme for the time integration. Developmental FVTD work for the thesis focused on algorithm development to analyze scattering and obtain RCS data for closed-surface perfect …

Modeling Plant Uptake Of Metal In Constructed Wetlands Supported By Experimentally Derived Uptake Rates, Michael B. Peake

Theses and Dissertations

Many communities and Air Force installations are using constructed wetlands to filter trace metals from their stormwater runoff. Constructed wetlands are attractive to industry for runoff mitigation because they are relatively cheap to build and operate and require little or no energy for operation. The purpose of this research project is to develop quantitative concepts for understanding the dynamics of metal uptake in constructed wetland plants by constructing a system dynamics model supported by experimental observation and offer environmental managers a tool to simulate, under a broad range of conditions, long term wetland exposure to stormwater runoff contaminated with trace …

Evaluation Of Design Tools For Rapid Prototyping Of Parallel Signal Processing Algorithms, James C. Savage

Theses and Dissertations

Digital signal processing (DSP) has become a popular method for handling not only signal processing, but communications, and control system applications. A DSP application of interest to the Air Force is high speed avionics processing. The real time computing requirements of avionics processing exceed the capabilities of current single chip DSP processors, and parallelization of multiple DSP processors is a solution to handle such requirements. Designing and implementing a parallel DSP algorithm has been a lengthy process often requiring different design tools and extensive programming experience. Through the use of integrated software development tools, rapid prototyping becomes possible by simulating …

The Effect Of University Characteristics On The Bicycle Transportation Mode And Helmet Usage, Carlton C. Urban

Masters Theses

By performing a statistical analysis on data collected from the Internet, this study sought to determine if designated characteristics of a university actually affect the bicycle transportation mode and helmet usage on college campuses. The focus group for this research experience involved bicycle commuters affiliated with universities in the United States. Through the establishment of a World Wide Web home page and on-line survey, the author obtained data concerning estimated bicycle and helmet usage percentages, and campus characteristic data from bicyclist responses. The Internet was used as an innovative approach to collecting data. Essentially the participant would simply locate the …

Impacts Of Hypothetical NoX Sources On Ozone Formation In East Tennessee, Mamun Ahmed

Masters Theses

This thesis studied the effects of hypothetical NO_x sources located in East Tennessee on the tropospheric ozone concentrations impacting the Great Smoky Mountains National Park (GSMNP) using the Urban Airshed Model (UAM). The product of this study is a technique of assessing the potential impact of a new or modified large NO_x source on ozone concentrations within a Class I area, which includes and up-to-date detailed emissions inventory. The East Tennessee Modeling Domain (ETMD) consists of 94 counties in six different states with an area of 75,900 km²: Tennessee (40), North Carolina (22), South Carolina (8), …

Corrosion Inhibitor For Reinforcing Steel In Concrete, Hanan Abdel Aziz Elnouhy

Archived Theses and Dissertations

No abstract provided.

Synergistic Decision-Making Systems: Using Models Of Decision-Making Behaviors And Resources To Design Better Decision-Making System, Ronald R. Carter

Masters Theses

Despite advances in decision-making systems, many practical issues remain unaddressed and much of the computer's potential for supporting decisions is unrealized. The existing systems are often limited to specific decision-making activities or domains, and they force the decision-maker to adopt a closed and inflexible way of doing things. What is needed is a new approach to building decision-making systems, one that is not focused on how decisions should be made, but on the behaviors and resources involved in decision-making and how they affect the results. This paper explores such an approach. It examines how models of decision-making behaviors and resources …

Residual Strength And Fatigue Characterization Of Scs-6/Ti-6-4, Sang-Myung Lee

Theses and Dissertations

Metal matrix composite have potential in a variety of aerospace applications, but they should be better understood before they can be employed. Despite the many studies that have contributed to characterizing the fatigue response of titanium alloy MMCs, few have researched the residual strength. The purpose of this study was to investigate the residual strength and the frequency effects on the residual strength of an unidirectional laminate of SCS-6/Ti-6-4, a titanium alloy matrix based composite under tension-tension, load-controlled conditions at elevated temperatures and different frequencies. Specimens were fatigued at frequencies of 1 and 0.01Hz, and at maximum stress of 900MPa …

Determining The Optimum Strategy Of Techniques From The Municipal Solid Waste Management Hierarchy To Maximize Social Value, Camille M. Still

Theses and Dissertations

Environmental managers must make difficult decisions regarding how to manage solid waste generation and disposal. The primary waste management alternatives are source reduction, recycling, composting, incineration, and landfilling often, waste management policies are based entirely on technical considerations and ignore that actual disposal practices depend on individuals' attitudes and behaviors. This research formulated a decision analysis model that incorporates social value measures to determine the waste management strategy that maximizes the individuals' willingness to participate. The social values that are important and that were considered in the decision support model to assist with making decisions about solid waste management were …

Analysis Of Multimode Low-Probability-Of-Intercept (Lpi) Communications With Atmospheric Effects, Ala Ghordlo

Theses and Dissertations

This research expanded Low Probability of Intercept (LPI) communications analysis in two areas. First, multimode communication was included to account for ground to ground and air to ground links in addition to the standard air to air links traditionally used in LPI analysis. The propagation equations for the three modes of interest were derived and included in LPI analytic models in the form of a mode quality factor to account for multimode LPI scenarios. This new quality factor was used in studying several communication and interception link combinations. Variations due to differences between the communication and interception modes were presented …

Performance Analysis Of Dynamic Routing Protocols In A Low Earth Orbit Satellite Data Network, Richard F. Janoso

Theses and Dissertations

Modern warfare is placing an increasing reliance on global communications. Currently under development are several Low Earth Orbit (LEO) satellite systems that propose to deliver voice and data traffic to subscribers anywhere on the globe. However, very little is known about the performance of conventional routing protocols under orbital conditions where the topology changes on a scale of minutes rather than days. This thesis compares two routing protocols in a LEO environment. One (Extended Bellman-Ford) is a conventional terrestrial routing protocol, while the other (Darting) is a new protocol which has been proposed as suitable for use in LEO networks. …

Model Predictive Control Of Aerospace Systems, Derek W. Ebdon

Theses and Dissertations

The primary objective of this thesis is to explore the fault tolerance capabilities of a state space formulation of MPC. Subsequent to a simulated control surface failure on the F-18 High Alpha Research Vehicle (HARV), the MPC controller will attempt to maintain stability and nominal performance while tracking a setpoint. Secondary objectives include studying the effect of data sample rate and MPC horizon lengths on system performance. These objectives will be accomplished using Matlab to develop the MPC controller and Simulink to demonstrate its effectiveness through simulation.

Experimental Investigation Of Transverse Supersonic Gaseous Injection Enhancement Into Supersonic Flow, Mark P. Wilson

Theses and Dissertations

In pursuit of more efficient and effective fuel-air mixing for a SCRAMJET combustor, this study was conducted to investigate relative near field enhancements of penetration and mixing of a discrete low-angled (25°) injected air jet into a supersonic (M=2.9) cross flow. The enhancements were achieved by injecting the transverse air jet parallel to the compression face of eight different ramp geometries. The jet-ramp interactions created collinear shock structures, baroclinic torque vorticity enhancement, ramp spillage enhanced vorticity, magnus effect penetration enhancement, and increased total pressure loss. Shadowgraph photography was used to identify the shock structures and interactions in the flow field. …

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 …

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 …

Applying Probabilistic Risk Assessment And Decision Analysis Techniques To Avoid Excessive Remedial Investigation Costs, Alejandro Hinojos

Theses and Dissertations

The majority of remediation resources have been consumed by costly and lengthy remedial investigation studies to characterize the human health risk. Unable to deal directly with the uncertainty resulting from the convolution of the uncertainties in a multitude of variables, and heavily persuaded by the liabilities, decision makers and regulators have relied on conservative assumptions and more studies to take appropriate actions. The main objective of this research is to provide tools and techniques to aid risk analysts in determining whether it would be beneficial to gather additional information or whether the decision to take an appropriate action can be …

Habitat Suitability Mapping Through Integration Of Multicriteria Evaluation Techniques With A Geographic Information System (Gis), Anthony A. Ference

Theses and Dissertations

The presence of an endangered species, the Pacific Pocket Mouse (PPM), in critical Marine Corps training areas aboard Camp Pendleton may adversely affect training activities that are crucial to meeting the Marine Corps' mission. Camp Pendleton must focus limited budgetary assets for live trapping surveys of the PPM in the areas of best habitat suitability and the purpose of this study was to develop a PPM habitat suitability map of Camp Pendleton. Suitability maps were developed by integrating expert opinion with the Camp Pendleton Geographic Information System (GIS) database.

Performance Analysis Of A Hartman Wavefront Sensor Used For Sensing Atmospheric Turbulence Statistics, Toby D. Reeves

Theses and Dissertations

Atmospheric turbulence parameters, such as Fried's coherence diameter, the outer scale of turbulence, and the turbulence power law, are related to the wavefront slope structure function (SSF). The SSF is defined as the second moment of the wavefront slope difference as a function of both time and position. Knowledge of the SSF allows turbulence parameters to be estimated. Hartmann wavefront sensor (H-WFS) slope measurements composed of both signal and noise, allow the SSF to be estimated by computing a mean square difference of H-WFS slope measurements. The quality of the SSF estimate is quantified by the signal-to-noise ratio (SNR) of …