Physical Sciences and Mathematics Commons^™

Efficient And Accurate Computation Of Non-Negative Anisotropic Group Scattering Cross Sections For Discrete Ordinates And Monte Carlo Radiation Transport, David W. Gerts

Theses and Dissertations

A new method for approximating anisotropic, multi-group scatter cross sections for use in discretized and Monte Carlo multi-group neutron transport is presented. The new method eliminates unphysical artifacts such as negative group scatter cross sections and falsely positive cross sections. Additionally, when combined with the discrete elements angular quadrature method, the new cross sections eliminate the lack of angular support in the discrete ordinates quadrature method. The new method generates piecewise-average group-to-group scatter cross sections. The accuracy and efficiency for calculating the discrete elements cross sections has improved by many orders of magnitude compared to DelGrande and Mathews previous implementation. …

Performance Analysis Of A Secure Ieee 802.11b Wireless Network Incorporating Personal Digital Assistants, John L. Camp

Theses and Dissertations

Research results of this thesis indicate very poor performance of a Wireless Local Area Network (WLAN) utilizing PDAs. Network throughput is adversely effected most by VPN implementation and slightly by increased file size. The client distance factor has virtually no effect on the throughput. The impact of each of these factor levels is small when compared to the magnitude of the overall mean throughput (<6%). The average network throughput with the PDA client is much lower than expected (=11,500 bps). This is attributed to several factors with degradation primarily resulting from limitations of the PDA hardware and O/S. Because of the low throughput values achieved (regardless if VPN is on or off), an operational WLAN with PDAs (as tested) is not feasible. Operational use of the network tested would require an in-depth analysis of the type of network traffic and performance required to maintain functionality. To deploy such a system, custom designed Winsock controls would need to be implemented to minimize limitations imposed by the PDA. As PDA technology continues to develop, future hardware and O/S functionality may provide a more robust platform for network communications. The battery life of the PDA and packet battery combination is observed to be about 164 minutes with additional jackets adding about 90 minutes each.

Long Range Forecast Possibilities For X-Band Radar Construction On Shemya, Brian K. Schroeder

Theses and Dissertations

Current moisture initialization sources lack the spatial and temporal resolution required for mesoscale moisture forecast accuracy critical for military operations. The Global Positioning System (GPS) satellite constellation provides an opportunity to extract accurate moisture observations based on the refraction of the GPS signal through the troposphere. GPS-derived precipitable water (PW) from two different research areas was independently compared with the Air Force Weather Agency s (AFWA's) MM5 PW model output. Results were concurrent with similar studies comparing GPS-derived PW with numerical weather models. The mean correlation in CONUS was 92.5%, while in Alaska it was 72.8%. Mean model biases were …

A Bdi Agent Software Development Process, Jeffrey M. Einhorn

Theses and Dissertations

As computer software continues to grow increasingly complex with each passing year, researchers continue to try and develop means to simplify software development. In this thesis, we propose a BDI agent software development process as the next evolution in software development. The goal of this research is to develop a process, which can be used to enable the creation of agent-based systems.

This thesis strives to present a practical software development process, which is useful to today's software engineer, by building upon current agent research and proven software engineering practices. Our BDI agent software development process is a systematic process, …

Land Usage Impacts On Springhead Salamander Populations, At Callaway Extended Properties, Harris County, Georgia, Neil Allen Pearce

Theses and Dissertations

Recent scientific studies have indicated that anrphibian populations appear to be declining in many areas of the world or exhibiting local population fluctuations. Some of the reasons given for this population decline are associated with land usage, and the negative biological impacts of many forms of land management practices. A study was conducted at the Callaway Gardens Extended Properties in Pine Mountain Georgia which compared the local aquatic salamander populations of five spring -fed streams in the Cason J. Callaway Memorial Forest, and five spring-fed streams in the Lower Valley Area. Using a cat ch-per-unit -effort sampling methodology, a comparison …

Using Gis And Land Use Data To Select Candidate Reference Sites For Stream Bioassessment, John Robert Olson

Theses and Dissertations

GIS was used to select candidate reference sites in Georgia to characterize the reference condition by sub-ecoregion for a rapid bioassessment of streams statewide. Instead of relying on best professional judgment or previous knowledge of a limited number of sites, we performed an objective evaluation of cumulative impact on all catchments using land use data sets. These included road and impoundment data from DLGs and Multi-Resolution Land use Consortium data. Land use impairment was measured as percentages of forest, urban, pasture, row crops, and barren area for both the entire catchment and for 10, 40, and 130-m riparian buffers, road …

A Unique Examination Of The Buffer Overflow Condition, Terry Bruce Gillette

Theses and Dissertations

Buffer overflows have been the most common form of security vulnerability for the last ten years. More over, buffer overflow vulnerabilities enable the type of exploits that dominate remote network penetration. As our reliance on commercial third party software is critical in the current computing environment one must consider the question of how these vulnerabilities are discovered in released proprietary software. This thesis presents research focused on the fundamental issues surrounding the buffer overflow vulnerability. The objective is to analyze and understand the technical nature of this type of vulnerability and, on the basis of this, develop an efficient generic …

Oceanic Transport And Life History Of The Tropical Western Atlantic Opossum Pipefish, Microphis Brachyurus Lineatus, Sarah Frias-Torres

Theses and Dissertations

The opossum pipefish, Microphis brachyurus lineatus, is a tropical migratory syngnathid. Adults live and breed in freshwater tributaries in specific emergent vegetative habitats. Juveniles associate with pelagic Sargassum in the tropical western Atlantic. Reproduction occurs during the wet season (May-November). Juvenile recruitment occurs during the dry season (December-April). The objective of this dissertation is to study the east Florida breeding population in the freshwater tributaries of the Indian River Lagoon and focus on: 1) Larval drift to the Gulf Stream and, 2) recruitment of pelagic juveniles from the Gulf Stream onto the freshwater breeding habitat. Pouch released larvae face sharp …

Quantification Of The Effects Of Data Denial And Limitation In Mm5 Initialization On Forecast Accuracy, Robert W. Evans

Theses and Dissertations

The current hub-and-spoke network in the European Theater is made up of locations built and organized around a Cold War threat. The threat of large-scale attrition warfare seems to have passed, and the threat of multiple, smaller scale contingencies has placed greater demands on the US military's ability to transport equipment and personnel to multiple locations simultaneously. This research effort utilizes a Multiple Objective Linear Programming (MOLP) model to analyze optimal hub locations in USEUCOM. The model used to analyze the network was developed in Microsoft Excel and followed MOLP techniques to determine the trade-offs between the two constructs of …

The Horizontal Extent Of Lightning Based On Altitude And Atmospheric Temperature, David R. Vollmer

Theses and Dissertations

Due to multiple factors, including an increase in military operations tempo and the improved resolution of meteorological models, demand for access to customized aviation weather products has increased exponentially. This has given rise to a need for a multi-purpose interactive aviation weather product generation software solution. This software solution must be platform-independent, multiple data source access configurable, robust, extensible or upgradeable, user-friendly, and an improvement over current visualization applications used in the operational military aviation weather community. This thesis determines whether Unidata MetApps meets these criteria. A software reuse and component-based engineering approach was taken in this thesis. Two experimental …

Gps-Derived Precipitable Water Compared With The Air Force Weather Agency's Mm5 Model Output, Patricia A. Vollmer

Theses and Dissertations

Lightning poses a threat to aircraft in flight. To mitigate this threat, the U.S. Air Force requested a study of lightning distances. Three-Dimensional lightning data were examined for this study, spanning 1 March 1997 to 31 May 2001 and obtained from the Lightning Detection and Ranging System (LDAR) at the Kennedy Space Center, FL. The LDAR data points were first grouped into lightning flashes and branches using spatial and temporal criteria. Rawinsonde data were vertically interpolated to determine the temperature at the flash source point and each branch end point. The horizontal distance from flash sources to branch end was …

A Comparison Of Coalescent Estimation Software, Kristen Piggott Shepherd

Theses and Dissertations

Coalescent theory is a method often used by population geneticists in order to make inferences about evolutionary parameters. The coalescent is a stochastic model that approximates ancestral relationships among genes. An understanding of the coalescent pattern of a sample of sequences, along with some knowledge of the mutations that have occurred, provides information about the evolutionary forces that have acted on the population. Processes such as migration, recombination, variable population size, or natural selection are the forces that affect the genealogies and lead to genetic variability in a sample. Coalescent theory provides a statistical description of the variability in the …

Suitability Of Unidata Metapps For Incorporation In Platform-Independent User-Customized Aviation Weather Products Generation Software, Harmen P. Visser

Theses and Dissertations

The Air Force Combat Climatology Center (AFCCC) is tasked to provide long-range seasonal forecasts for worldwide locations. Currently, the best long-range temperature forecasts the weather community has are the climatological standard normals. This study creates a stepping-stone into the solution of long-range forecasting by finding a process to predict temperatures better than those using climatological standard normals or simple frequency distributions of occurrences. Northern Hemispheric teleconnection indices and the standardized Southern Oscillation index are statistically compared to three-month summed Heating Degree Days (HDDs) and Cooling Degree Days (CDDs) at 14 U.S. locations. First, linear regression was accomplished. The results showed …

Using An Inductive Learning Algorithm To Improve Antibody Generation In A Single Packet Computer Defense Immune System, Russell J. Aycock

Theses and Dissertations

Coherent optical sources in the mid-infrared region (mid-IR) are important fundamental tools for infrared countermeasures and battlefield remote sensing. Nonlinear optical effects can be applied to convert existing near-IR laser sources to radiate in the mid-IR. This research focused on achieving such a conversion with a quasi-phase matched optical parametric oscillators using orientation-patterned gallium arsenide (OPGaAs), a material that can be quasi-phased matched by periodically reversing the crystal structure during the epitaxial growth process. Although non-linear optical conversion was not ultimately achieved during this research, many valuable lessons were learned from working with this material. This thesis reviews the theory …

An Anion Characterization Of A Constructed Wetland Used For Chlorinated Ethene Remediation, Bradley M. Bugg

Theses and Dissertations

Chlorinated ethenes physical properties as well as its ubiquitous state at DOD installations makes it a priority for innovative remediation efforts. Current techniques are expensive and time consuming to maintain. Constructed wetlands suggest an inexpensive and operational alternative to conventional technologies. Sub-surface flow wetlands provide the anaerobic zones necessary to reduce the recalcitrant chlorinated solvents prior to anaerobic or aerobic mineralization of its daughter products. A vertical flow cell to include sequential sedimentary layers of two hydric soil lifts and a mix of hydric soil and woody compost was the subject of this investigation. This study focused on the statistical …

Fabrication And Cold-Flow Testing Of Subscale Space-Based Laser Geometry, Scott E. Bergren

Theses and Dissertations

The objectives of this research were to build a facility that could simulate the expected fluid flow properties in the conceptual Space Based Laser Integrated Flight Experiment (SBL IFX) gas dynamic laser using cold-flow, and to investigate the performance of the model. A 1/5th scale model was fabricated and mated to a blow-down/vacuum wind tunnel. Using rapid data acquisition and schlieren photography the diffuser was determined to initially produce similar fluid flow to the SBL IFX, but rapidly became subsonic due to a transient normal shock wave formed when the wind tunnel was started.

Bubble World - A Novel Visual Information Retrieval Technique, Christopher L. Van Berendonck

Theses and Dissertations

With the tremendous growth of published electronic information sources in the last decade and the unprecedented reliance on this information to succeed in day-to-day operations, comes the expectation of finding the right information at the right time. Sentential interfaces are currently the only viable solution for searching through large infospheres of unstructured information, however, the simplistic nature of their interaction model and lack of cognitive amplification they can provide severely limit the performance of the interface. Visual information retrieval systems are emerging as possible candidate replacements for the more traditional interfaces, but many lack the cognitive framework to support the …

Fabrication Techniques For Micro-Optical Device Arrays, Ryan D. Conk

Theses and Dissertations

Micro-optical devices are vital components of conventional military data storage, sensor, and communication systems. Two types of micro-optical device arrays exist: individually addressable and matrix addressable. The matrix addressable array has a drastically reduced number of metal lines and can potentially be fabricated into large, dense (over 1k elements) arrays. Such arrays are expected to enable the development of extremely high bandwidth optical interconnect systems for future military applications including optical computing and short-haul fiber optical communication systems. I investigate new fabrication techniques for the assembly of dense matrix-addressed arrays of micro-optical devices such as vertical-cavity surface-emitting lasers. Using a …

Translation And Rotation Invariant Multiscale Image Registration, Jennifer L. Manfra

Theses and Dissertations

The most recent research involved registering images in the presence of translations and rotations using one iteration of the redundant discrete wavelet transform. We extend this work by creating a new multiscale transform to register two images with translation or rotation differences, independent of scale differences between the images. Our two-dimensional multiscale transform uses an innovative combination of lowpass filtering and the continuous wavelet transform to mimic the two-dimensional redundant discrete wavelet transform. This allows us to obtain multiple subbands at various scales while maintaining the desirable properties of the redundant discrete wavelet transform. Whereas the discrete wavelet transform produces …

Synthesis Of 3-Dimensional Lightning Data And Weather Radar Data To Determine The Distance That Naturally Occurring Lightning Travels From Thunderstorms, Lee A. Nelson

Theses and Dissertations

Military base weather stations are required to issue lightning warnings to protect military equipment and personnel. The issuance of warnings is based on a 5 nautical mile (n mi) distance criterion. This criterion appears to have evolved over time as a balance between safety and mission impact. The goal of this thesis is to challenge the 5 n mi lightning warning criteria by quantifying the distance that CG lightning travels. A secondary goal is to examine the characteristics of the peak current of CG lightning strokes to determine if a relationship exists between peak current, the distance a stroke travels, …

Identifying Enlisted Stay And Leave Population Characteristics With Discriminant Analysis, Zabrina Y. Hoggard

Theses and Dissertations

The research contribution of this thesis is the first known integrated architecture and feature selection algorithm for Radial Basis Neural Networks (RBNNs). The objective is to apply the network iteratively to determine the final architecture and feature set used to evaluate a problem. Additionally, this thesis compares three different classification techniques, Discriminant Analysis (DA), Feed-Forward Neural Networks (FFN) and RBNNs against several hard to solve problems. These problems were used to evaluate general classifier performance as well as the performance of the feature selection techniques. This thesis describes the classification techniques as well as the measures used to evaluate them. …

Data Mining Feature Subset Weighting And Selection Using Genetic Algorithms, Okan Yilmaz

Theses and Dissertations

We present a simple genetic algorithm (sGA), which is developed under Genetic Rule and Classifier Construction Environment (GRaCCE) to solve feature subset selection and weighting problem to have better classification accuracy on k-nearest neighborhood (KNN) algorithm. Our hypotheses are that weighting the features will affect the performance of the KNN algorithm and will cause better classification accuracy rate than that of binary classification. The weighted-sGA algorithm uses real-value chromosomes to find the weights for features and binary-sGA uses integer-value chromosomes to select the subset of features from original feature set. A Repair algorithm is developed for weighted-sGA algorithm to guarantee …

Verification And Comparison Of Polar Mm5 And Afwa Mm5 Forecasts Over Alaska, William E. Courtemanche

Theses and Dissertations

This research compares biases of the Reisner Mixed-Phase Explicit Moisture Microphysics graupel and non-granpel schemes to determine if including graupel and riming processes within the Fifth Generation Mesoscale Model (MM5) will lead to improved forecasts of winter precipitation for Korea and Japan. MM5 forecasts were generated every 12 hours for a 20 days case period from January 1998. Model derived meteorological fields were interpolated to the station coordinates of four verification sites within the East Asian domain and radiosonde observations were used to compare the differences between the average temperature and water vapor errors of the two cloud microphysics schemes. …

Using Relational Schemata In A Computer Immune System To Detect Multiple-Packet Network Intrusions, John L. Bebo

Theses and Dissertations

Given the increasingly prominent cyber-based threat, there are substantial research and development efforts underway in network and host-based intrusion detection using single-packet traffic analysis. However, there is a noticeable lack of research and development in the intrusion detection realm with regard to attacks that span multiple packets. This leaves a conspicuous gap in intrusion detection capability because not all attacks can be found by examining single packets alone. Some attacks may only be detected by examining multiple network packets collectively, considering how they relate to the "big picture," not how they are represented as individual packets. This research demonstrates a …

Chromate Content Bias Versus Overspray Particle Size In Three Aircraft Primer Paints, Brian S. Rhodes

Theses and Dissertations

The United States Air Force relies on the corrosion inhibiting properties of chromate-containing primer paints to protect the aluminum skin of its aircraft. Hexavalent chromium (Cr⁶⁺) the ingredient responsible for the corrosion inhibiting characteristics of these primers is a known human carcinogen. The concentration of Cr⁶⁺ in different particle sizes of paint overspray is important to understand health implications to painters as well as filtration efficiency. Previous research indicates disproportionately less Cr⁶⁺ content in smaller particles collected in the overspray of solvent-based epoxy-polyamide paint primers (MIL-P-2377G). This research explores the possibility of a particle size bias …

Application Of The Wind Gust Estimate And Comparison To The Afwa Mm5 Wind Gust Algorithm, Kevin W. Lacroix

Theses and Dissertations

The Air Force Weather Agency (AFWA) runs the Penn State/NCAR Mesoscale Model 5 (MM5) as their main mesoscale weather forecast model. One of the post-processing procedures is a diagnostic algorithm, which is used to help identify convective and non-convective wind gusts. O. Brassuer has identified a new Wind Gust Estimate (WGE), as a physically based method of computing non-convective wind gusts. The WGE surmises that Turbulent Kinetic Energy (TKE) transfers the momentum of faster upper-air winds to the surface, overcoming the buoyant energy of the surface layer. This work converts Brassuer's WGE to FORTRAN code and utilizing post-processed CONUS AFWA …

Carrier Dynamics In Mid-Infrared Quantum Well Lasers Using Time-Resolved Photoluminescence, Steven M. Gorski

Theses and Dissertations

Research in mid-infrared laser technology has uncovered numerous applications for commercial and government use. A limiting factor for mid-infrared semiconductors is nonradiative recombination, which is a process that produces excess heat without emitting a photon. Nonradiative recombination mechanisms occur over a short time period and difficult to measure. Growth methods have significantly reduced the nonradiative recombination in some materials. The objective of this research is to further the understanding of how quantum well structures impact carrier recombination. InAsSb/InAlASb and InAs/GaInSb quantum well structures were studied with time-resolved photoluminescence utilizing upconversion, a non-linear wave mixing technique. This research reports Shockley-Read-Hall, radiative, …

A Visual Meta-Language For Generic Modeling, Hakan Canli

Theses and Dissertations

This research examines the usefulness of a visual meta-language (VLGM Visual Language for Generic Modeling) developed for the specification of components and relations in a modeling domain. The language is designed to allow software tools to interpret specifications and automatically provide modeling environments. VLGM makes use of the object-orientated software engineering methodology. It defines four types of special classes and three types of relations between them. Data types and primitive types are allocated with several attributes to provide restrictions and enable consistency checks over models. As part of this research a software tool was designed. The tool provides a workspace …

Estimation Of Atmospheric Precipitable Water Using The Global Positioning System, David A. Garay

Theses and Dissertations

This research focuses on using the Global Positioning System (GPS) for atmospheric precipitable water (PW) estimation. Water vapor, measured in terms of PW, plays a crucial role in atmospheric processes and short-term weather forecasting. Traditional methodologies for measuring atmospheric water vapor distributions have known inadequacies, resulting in the motivation to gain good water vapor characterization via GPS. The ability to accurately forecast cloud formation and other weather phenomenon is critical, especially in the case of military operations. Using a network of GPS receivers, it is possible to estimate precipitable water throughout the network region with better accuracy than traditional methods …

Designing An Algorithm To Predict The Intensity Of The Severe Weather Season, Hugh J. Freestrom

Theses and Dissertations

The Mesoscale Model 5th Generation (MM5) is used for operational support to Air Force missions in the Alaskan Theater. The 11th Operational Weather squadron has identified problems with the MM5 producing excessively warm surface temperatures. The Polar MM5 (PMM5), developed by the Byrd Polar Research Center for high latitude ice sheets, is tested over the Alaskan domains used by the Air Force Weather Agency to determine the utility in replacing the MM5 with the PMM5. The verification of surface temperature, pressure and wind as well as upper-air temperature, geopotential height, and relative humidity of 27-hour PMM5 forecasts are compared to …