Physical Sciences and Mathematics Commons^™

Controlling Laser High-Order Harmonic Generation Using Weak Counter-Propagating Light, Sergei Leonidovich Voronov

Theses and Dissertations

Laser high-order harmonic generation in the presence of relatively weak interfering light is investigated. The interfering pulses intersect the primary harmonic-generating laser pulse at the laser focus. The interfering light creates a standing intensity and phase modulation on the field, which disrupts microscopic phase matching and shuts down local high harmonic production. Suppression of the 23rd harmonic (by two orders of magnitude) is observed when a counter-propagating interfering pulse of light is introduced. A sequence of counter-propagating pulses can be used to shut down harmonic production in out-of-phase zones of the generating volume to achieve quasi phase matching. Harmonic emission …

Active Processor Scheduling Using Evolution Algorithms, David J. Caswell

Theses and Dissertations

The allocation of processes to processors has long been of interest to engineers. The processor allocation problem considered here assigns multiple applications onto a computing system. With this algorithm researchers could more efficiently examine real-time sensor data like that used by United States Air Force digital signal processing efforts or real-time aerosol hazard detection as examined by the Department of Homeland Security. Different choices for the design of a load balancing algorithm are examined in both the problem and algorithm domains. Evolutionary algorithms are used to find near-optimal solutions. These algorithms incorporate multiobjective coevolutionary and parallel principles to create an …

Power Scaling Feasibility Of Chromium-Doped Ii-Vi Laser Sources And The Demonstration Of A Chromium-Doped Zinc Selenide Face-Cooled Disk Laser, Jason B. Mckay

Theses and Dissertations

Tunable lasers in the 2-4 µm wavelength range are needed for Air Force sensor applications. Chromium-doped II-VI materials are a promising class of laser material for tunable operation in this wavelength range, but until recently had not produced enough output power to meet application requirements. This dissertation investigates Cr²⁺:II-VI material properties and potential laser designs, then experimentally demonstrates and analyzes the performance of a Cr²⁺:ZnSe disk laser design that can produce sufficient output power. Cr²⁺:II-VI laser materials are found to be susceptible to overheating and thermal lensing, but are otherwise satisfactory laser materials. The …

Determining The Mobility Of Metals Through Coal Combustion Byproducts In Surface Impoundments By Analyzing Leachate From Modified Saturated Hydraulic Conductivity Tests, Michael Joseph Trofinoff

Theses and Dissertations

Surface impoundments are used extensively throughout the utility industry to store the combustion byproducts, or ash, from coal-fired generating facilities. Following combustion, the metals, naturally contained within coal at low concentrations, may become highly concentrated within the ash. These combustion byproducts are then piped out in a water-ash slurry to the surface impoundments where the ash weathers to- a clay- like substance after approximately 10 years. It is feared that these metals that are contained within the ash could possibly leach into the ground and contaminate the local groundwater. Utilizing a open column percolation test to determine the hydraulic conductivity …

Finite Extinction Time For Non-Linear Absorption-Diffusion Equations, Jacob B. Goldberg

Theses and Dissertations

In this thesis, we develop a numerical method in order to approximate the solutions of one-dimensional, non-linear absorption-diffusion equations. We test our method for accuracy against a linear diffusion equation with a solution that can be written in closed form. We then test various types of diffusion and absorption terms to determine which ones produce extinction in finite time. We also develop a numerical method to computationally solve diffusion-free equations. We compare the numerical solutions of the one-dimensional, non-linear absorption-diffusion equation and the diffusion-free equation and we find that for the cases tested, the numerical absorption-diffusion solutions are always less …

High Energy Laser Pointing Through Extended Turbulence, Jason A. Tellez

Theses and Dissertations

The airborne laser (ABL) uses adaptive optics to compensate the atmospheric turbulence between the ABL and the target. The primary purpose of this compensation is to increase the energy density of the energy laser at the target. However, the specifics of the engagement scenario require the tracking point of reference and the adaptive optics point of reference to be located at different points on the target. This research considers the effects of tracking a target in one direction while compensating for atmospheric turbulence in a different directions. The target references used are a point source and a rectangle, while a …

Adaptive Harmonic Balance Method For Unsteady, Nonlinear, One-Dimensional Periodic Flows, Raymond C. Maple

Theses and Dissertations

A new adaptive split-domain harmonic balance computational fluid dynamics (CFD) method is developed to solve highly nonlinear time-periodic flows such as those found in turbomachinery. The basic harmonic balance CFD method transforms an unsteady time-periodic problem into a steady-state problem by assuming a solution in the form of a Fourier series in time. The new method employs a unique multi-domain split-operator solution technique to remove a large-series stability restriction present in previous harmonic balance CFD approaches. In addition, the new method adapts the frequency content to the flow, starting with a small number of Fourier frequencies and augmenting the frequency …

Comparing Clustering Algorithms For Use With Genomic And Proteomic Data, Rebecca A. Olson

Theses and Dissertations

The Human Genome Project and related projects have resulted in the development of a number of new experimental and analytic tools for use in genomic and proteomic research. In the area of toxicogenomics, researchers are concerned with how genes react to exposure to certain chemicals. The United States Air Force is interested in the effect of exposure to mission-essential chemicals. Although military personnel may come into contact with chemicals such as hydrazine, risk assessment is usually very limited. On the genomic level, risk assessment is a multi-stop and multi-disciplinary process. The process begins with an experiment that exposes cells to …

Analysis For Cooperative Behavior Effectiveness Of Autonomous Wide Area Search Munitions, Sang M. Park

Theses and Dissertations

The purpose of this study is to investigate how a simulation model can accurately represent the performance of the autonomous wide area search munitions, and to find the effectiveness of the cooperative behavior on the autonomous munitions. Though it does not provide a practical solution for the development of the autonomous wide area search munitions, this research will show some meaningful allocations of the munitions tasks that are applicable to the development of the autonomous munitions. For the first phase, this thesis presents how accurately a simplified simulation model can represent a proposed weapon system by comparing the simulation results …

Visual Execution Analysis For Multiagent Systems, Chong Kil

Theses and Dissertations

Multiagent systems have become increasingly important in developing complex software systems. Multiagent systems introduce collective intelligence and provide benefits such as flexibility, scalability, decentralization, and increased reliability. A software agent is a high-level software abstraction that is capable of performing given tasks in an environment without human intervention. Although multiagent systems provide a convenient and powerful way to organize complex software systems, developing such system is very complicated. To help manage this complexity this research develops a methodology and technique for analyzing, monitoring and troubleshooting multiagent systems execution. This is accomplished by visualizing a multiagent system at multiple levels of …

A Formal Method To Analyze Framework-Based Software, Trent N. Larson

Theses and Dissertations

Software systems are frequently designed using abstractions that make software verification tractable. Specifically, by choosing meaningful, formal abstractions for interfaces and then designing according to those interfaces, one can verify entire systems according to behavioral predicates. While impractical for systems in general, framework-based software architectures are a type of system for which formal analysis can be beneficial and practical over the life of the system. We present a method to formally analyze behavioral properties of framework-based software with higher-order logic and then demonstrate its utility for a significant, modern system.

Availability Of Organochlorides And Accumulation In Populations Of Tadarida Brasiliensis (Free-Tailed Bat) And Eptesicus Fuscus (Big Brown Bat), Michelle Lee Smith

Theses and Dissertations

Organochlorides were historically effective in controlling a wide range of pests. However, organochlorides have proved to present many problems to the health and welfare of other organisms. Due to these problems, especially declines in wildlife populations, organochlorides were restricted in the 1970's and a majority of them were banned in the mid to late 1980's. The effects of organochlorides on bats such as Tadarida brasiliensis and Eptesicus fuscus have been intensively studied. The effects can range from problems with reproduction to mortality. My analysis of populations of T. brasiliensis and E. fuscus showed that organochlorides are still present in the …

Using The Index Of Biotic Integrity Of Fish Communities To Evaluate Habitat Quality In Middle Chattahoochee River Tributaries, Theodor W. Roever

Theses and Dissertations

An ichthyological survey was conducted within the lower Piedmont and upper Coastal Plain physiographic regions of the middle Chattahoochee River drainage basin between August 1998 and September 2000. Sampling was conducted by Columbus State University (CSU) under contract to Columbus Water Works for the purpose of obtaining biological measurements of watershed health. Objectives of the survey were the establishment of a data baseline of IBI scores for this ecoregion and to ascertain if there was a correlation between the IBI score and human influence. The thesis to be tested is: 'Fish community IBI scores of different watersheds within the Middle …

Design And Implementation Of An Online Database Panel, Frenny Thomas

Theses and Dissertations

There is a growing need for administrative panels such as the one described in this project. More and more website administrators wish to make changes to their online business without having to directly modify the database file. This project provides the perfect solution for this scenario by placing all database access on the World Wide Web. Administrators can now use this software to add, edit, and delete tables, fields, and records. Additionally, users will be able to generate queries without knowledge of Structured Query Language. This project acts as a summary of my computer science education at this university by …

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 …

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 …

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 …

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 …

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 …

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 …

Distributed Beacon Requirements For Branch Point Tolerant Laser Beam Compensation In Extended Atmospheric Turbulence, Virgil E. Zetterlind Iii

Theses and Dissertations

Branch point tolerant phase reconstructors can vastly improve adaptive optic system performance in extended atmospheric turbulence. This thesis explores the performance bounds of two such reconstructors Goldstein's algorithm and hidden phase. A least squares reconstructor is implemented for comparison. System performance is presented for various scenarios, including correction time-delays, wave-front sensor noise, and extended beacons. These scenarios are of interest for laser communication and directed energy systems such as Airborne Laser. Performance bounds are obtained through wave-optics simulation. The extended beacon propagation geometry approximates the USAF AFRL-DE North Oscura Peak range. Results show that branch point tolerant reconstructors outperform least …

Verification Of Mm5 Cloud Microphysics Schemes For East Asia, Dean J. Carter

Theses and Dissertations

Using the 3-Dimensional Variational Analysis data assimilation scheme and the (MM5), input observations were denied in three different categories: total, upper air, and surface observation denial. Two control groups were run using all available data as received by AFWA. The main control group used a 6 hours old first guess as a baseline. The data denied test cases and the secondary control group used a 30-hour old first guess because it was not possible to deny data from the first guess. The secondary control group was used to estimate errors resulting from the use of different first guess forecasts between …