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Shockwave Interactions With Argon Glow Discharges, Nicholas S. Siefert
Shockwave Interactions With Argon Glow Discharges, Nicholas S. Siefert
Theses and Dissertations
The purpose of this research was study shock wave interactions with argon glow discharges. Specifically, this thesis sought to answer whether it is possible to compress nonequilibrium electrons at the shock wave. The results in the thesis found that both equilibrium and nonequilibrium electrons could be compressed at the shock front. The double layer at the shock front, normalized by electron temperature, matched the calculated values for the double layer within a factor or two in all cases. The results also demonstrate that excited metastable states can be compressed at the shock front, as well. The culmination of this effort …
Using Agent-Based Modeling To Search For Elusive Hiding Targets, Jeffrey E. Rucker
Using Agent-Based Modeling To Search For Elusive Hiding Targets, Jeffrey E. Rucker
Theses and Dissertations
The SCUD hunt problem that emerged during Operation Desert Storm has become a source of great interest to major commands like Air Combat Command. One of the metrics used to measure the effectiveness of our operations in a SCUD hunt is time to detect and target. We use the agent-based System Effectiveness and Analysis Simulation (SEAS) to provide a simulation environment in which all the elements of a SCUD hunt mission can adequately be modeled. Our Blue Force agents are modeled as multirole fighters, satellites and unmanned aerial vehicles (UAV) with various sensor capabilities. The Red Force agents are modeled …
Validation Of Methods To Measure Mass Flux Of A Groundwater Contaminant, Hyouk Yoon
Validation Of Methods To Measure Mass Flux Of A Groundwater Contaminant, Hyouk Yoon
Theses and Dissertations
In this study, flux measurements obtained using two methods are compared with known mass fluxes in a meso-scale three-dimensional artificial aquifer. One method, the tandem recirculating well (TRW) method, is applied using two different techniques. One technique is simple and inexpensive, only requiring measurement of heads, while the second technique requires conducting a tracer test. The second method, the integrated pump test (IPT) method, requires use of one or more pumping and observation wells in various configurations. The results of the experiments in the artificial aquifer show that the most expensive technique, the TRW method using tracers, provides the most …
An Exploration Of The Effects Of Genetic Drift On The Endangered Red-Cockaded Woodpecker, Ryan E. Nelson
An Exploration Of The Effects Of Genetic Drift On The Endangered Red-Cockaded Woodpecker, Ryan E. Nelson
Theses and Dissertations
The Red-cockaded Woodpecker (RCW) (Picoides borealis) is classified as an endangered species under the Endangered Species Act of 1973 due to habitat fragmentation and prescribed burn suppression. Given the endangerment of the RCW, the genetic variation of the small populations will decrease over time due to random genetic drift. The only method of battling the negative effects of random genetic drift is to move, or translocate, genetically diverse birds into the fragmented populations thereby increasing the genetic diversity of the small populations. The objective of this research effort was to explore the effects of random genetic drift on small RCW …
Formal Mitigation Strategies For The Insider Threat: A Security Model And Risk Analysis Framework, Jonathan W. Butts
Formal Mitigation Strategies For The Insider Threat: A Security Model And Risk Analysis Framework, Jonathan W. Butts
Theses and Dissertations
The advancement of technology and reliance on information systems have fostered an environment of sharing and trust. The rapid growth and dependence on these systems, however, creates an increased risk associated with the insider threat. The insider threat is one of the most challenging problems facing the security of information systems because the insider already has capabilities within the system. Despite research efforts to prevent and detect insiders, organizations remain susceptible to this threat because of inadequate security policies and a willingness of some individuals to betray their organization. To investigate these issues, a formal security model and risk analysis …
Prediction Of The Temporal Evolution Of Solar X-Ray Flares, Aaron J. Williams
Prediction Of The Temporal Evolution Of Solar X-Ray Flares, Aaron J. Williams
Theses and Dissertations
A solar flare is an explosive release of stored magnetic energy on the Sun. Much of this energy is converted into x-ray photons which escape into space. As a solar flare begins, the 1-8 Å x-ray photon flux at Earth’s orbit, as measured by the GOES satellite, rapidly increases. It quickly reaches a peak and slowly decays. A plot of this flux exhibits an approximate lognormal shape. A lognormal function becomes a normal, symmetric, function when the logarithm of the independent variable is taken. Once the peak flux is reached, this symmetry is used to make a prediction of the …
Evaluating Km Journal Content: An Assessment Of Trends (2000-2005), Donnie O. Harp
Evaluating Km Journal Content: An Assessment Of Trends (2000-2005), Donnie O. Harp
Theses and Dissertations
Knowledge management (KM) has been receiving ever increasing attention from researchers and practitioners, especially over the last 5 years. Consequently, some researchers and practitioners now believe that KM should be its own discipline and have established KM-specific journals in an effort to further this idea. Many of these journal founders believe that KM has emerged as a mixture of many disciplines and have written the goal of being interdisciplinary into their charters. This research reviews the KM literature published in KM-specific journals from 2000 to 2005. Specifically, using a content analysis methodology, this research reviews and analyzes the body of …
Characterization Of Pulse Detonation Engine Performance With Varying Free Stream Stagnation Pressure Levels, Wesley R. Knick
Characterization Of Pulse Detonation Engine Performance With Varying Free Stream Stagnation Pressure Levels, Wesley R. Knick
Theses and Dissertations
A pulse detonation engine operates on the principle that a fuel-air mixture injected into a tube will ignite and undergo a transition from a deflagration to a detonation and exit the tube at supersonic velocities. Studies in the field of combustion have shown that both ignition time and deflagration to detonation transition time can vary as a function of pressure. It can be hypothesized that if ignition and deflagration to detonation transition times can be reduced by increasing the free stream stagnation pressure level of the tube, it would then be possible to shorten the detonation tube length and increase …
Carrier Lifetime Dynamics Of Epitaxial Layer Hvpe Gallium Arsenide Using Time-Resolved Experiments, Wayne E. Eikenberry
Carrier Lifetime Dynamics Of Epitaxial Layer Hvpe Gallium Arsenide Using Time-Resolved Experiments, Wayne E. Eikenberry
Theses and Dissertations
GaAs is a potential semiconductor material for producing both mid-infrared and terahertz radiation using the new technique of quasi-phase matching in an orientationally patterned GaAs (OP-GaAs) crystal. OP-GaAs is grown using a fast growth process called hydride vapor phase epitaxy (HVPE). Unfortunately, HVPE produces a high number of defects. These defects cause Shockley-Read-Hall recombination rates to dominate over Auger and radiative recombination rates. The carrier lifetime from four OP-GaAs samples are reported here using two different experimental techniques. The first experiment used a streak camera to measure the carrier lifetime via time-resolved photoluminescence. The temporal resolution of the streak camera …
Improving Intercontinental Ballistic Missile Maintenance Scheduling Through The Use Of Location Analysis Methodologies, Dale L. Overholts Ii
Improving Intercontinental Ballistic Missile Maintenance Scheduling Through The Use Of Location Analysis Methodologies, Dale L. Overholts Ii
Theses and Dissertations
The events of September 11, 2001 have led to increased security requirements for all ICBM-related activities. Missile maintenance managers must explore new scheduling techniques to sustain weapon system readiness levels in light of published security enhancements. The problem of improving missile maintenance scheduling is modeled as a two-stage heuristic that utilizes the maximal covering location problem methodology. Maintenance activities are categorized and weighted according to published priority designation and mission impact. The model’s first stage seeks to select two security umbrellas that maximize the weighted sum of maintenance activities. Stage two seeks to determine a maintenance schedule comprised of launch …
Combining Quality Of Service And Topology Control In Directional Hybrid Wireless Networks, Michael C. Erwin
Combining Quality Of Service And Topology Control In Directional Hybrid Wireless Networks, Michael C. Erwin
Theses and Dissertations
Recent advancements in information and communications technology are changing the information environment in both quantitative and qualitative measures. The developments in directional wireless capabilities necessitate the ability to model these new capabilities, especially in dynamic environments typical of military combat operations. This thesis establishes a foundation for the definition and consideration of the unique network characteristics and requirements introduced by this novel instance of the Network Design Problem (NDP). Developed are a Mixed-Integer Linear Program (MILP) formulation and two heuristic strategies for solving the NDP. A third solution strategy using the MILP formulation with a degree-constrained Minimum Spanning Tree starting …
Algebra Of Tankers, Margaret M. Romero
Algebra Of Tankers, Margaret M. Romero
Theses and Dissertations
The Air Force's aerial refueling tanker aircraft provide essential support for deployment and employment of combat and combat support aircraft, by extending their endurance and enhancing fighting efficiency. As the lead command for air refuelers, Air Mobility Command (AMC) must frequently examine the capability of current and proposed tanker fleets to meet mission requirements due to limited tanker resources. Analysts in AMC primarily use the Combined Mating and Ranging Plans System to provide actual tanker/receiver aircraft schedules and flight plans that take into account numerous system constraints. However, this tool can take weeks to run. Even recently developed quick look …
Optimizing Mean Mission Duration For Multiple-Payload Satellites, John A. Flory
Optimizing Mean Mission Duration For Multiple-Payload Satellites, John A. Flory
Theses and Dissertations
This thesis addresses the problem of optimally selecting and specifying satellite payloads for inclusion on a satellite bus to be launched into a constellation. The objective is to select and specify payloads so that the total lifetime utility of the constellation is maximized. The satellite bus is limited by finite power, weight, volume, and cost constraints. This problem is modeled as a classical knapsack problem in one and multiple dimensions, and dynamic programming and binary integer programming formulations are provided to solve the problem. Due to the computational complexity of the problem, the solution techniques include exact methods as well …
A Multi-Pass Construction Heuristic For The Aggregated Airlift Problem, Stephen T. O'Leary
A Multi-Pass Construction Heuristic For The Aggregated Airlift Problem, Stephen T. O'Leary
Theses and Dissertations
To support the capabilities for precision strike, close air support, intelligence, surveillance, reconnaissance, air mobility and air refueling the Air Force has over 26,000 Airmen deployed from over 80 military installations to Forward Operating Locations (FOLs) in over 21 countries. This research creates a multi-pass construction heuristic to solve the aggregated airlift problem associated with the transportation of these 26,000 deployed Airmen. We are given a Time Phased Force Deployment Document (TPFDD) containing a list of personnel scheduled for deployment, their base of origin, Point of Debarkation (POD), FOL, and Required Delivery Date (RDD). The goal is to aggregate the …
Optimization Of A Multi-Echelon Repair System Via Generalized Pattern Search With Ranking And Selection: A Computational Study, Derek D. Tharaldson
Optimization Of A Multi-Echelon Repair System Via Generalized Pattern Search With Ranking And Selection: A Computational Study, Derek D. Tharaldson
Theses and Dissertations
With increasing developments in computer technology and available software, simulation is becoming a widely used tool to model, analyze, and improve a real world system or process. However, simulation in itself is not an optimization approach. Common optimization procedures require either an explicit mathematical formulation or numerous function evaluations at improving iterative points. Mathematical formulation is generally impossible for problems where simulation is relevant, which are characteristically the types of problems that arise in practical applications. Further complicating matters is the variability in the simulation response which can cause problems in iterative techniques using the simulation model as a function …
A Methodology For Performing Effects-Based Assessments, Benjamin A. Thoele
A Methodology For Performing Effects-Based Assessments, Benjamin A. Thoele
Theses and Dissertations
In order to bring the doctrine of Effects-Based Operations (EBO) into a fully operational capability, Effects-Based Assessment (EBA) must provide relevant insight to the commander and his planning staff. Assessments of an effects-based plan and execution must include an assessment of the effects of a campaign on the enemy in addition to an assessment of the accomplishment of friendly actions taken to achieve the desired effects. Determining the effects of a campaign requires an analysis of the dynamics of the enemy systems. EBA must be able to recognize the states of the enemy's systems as the system states change over …
An Adaptable Energy-Efficient Medium Access Control Protocol For Wireless Sensor Networks, Justin T. Kautz
An Adaptable Energy-Efficient Medium Access Control Protocol For Wireless Sensor Networks, Justin T. Kautz
Theses and Dissertations
Wireless networks have become ubiquitous recently and therefore their usefulness has also become more extensive. Wireless sensor networks (WSN) detect environmental information with sensors in remote settings. One problem facing WSNs is the inability to resupply power to these energy-constrained devices due to their remoteness. Therefore to extend a WSN's effectiveness, the lifetime of the network must be increased by making them as energy efficient as possible. An energy efficient medium access control (MAC) can boost a WSN's lifetime. This research creates a MAC protocol called Adaptive sensor Medium Access Control (AMAC) which is based on Sensor Medium Access Control …
Flashlight: A Dynamic Detector Of Shared State, Race Conditions, And Locking Models In Concurrent Java Programs, Scott C. Hale
Flashlight: A Dynamic Detector Of Shared State, Race Conditions, And Locking Models In Concurrent Java Programs, Scott C. Hale
Theses and Dissertations
Concurrent Java programs are difficult to understand and implement correctly. This difficultly leads to code faults that are the source of many real-world reliability and security problems. Many factors contribute to concurrency faults in Java code; for example, programmers may not understand Java language semantics or, when using a Java library or framework, may not understand that their resulting program is concurrent. This thesis describes a dynamic analysis tool, named FlashLight, that detects shared state and possible race conditions within a program. FlashLight illuminates the concurrency within a program for programmers who are wholly or partially "in the dark" about …
Metamorphism As A Software Protection For Non-Malicious Code, Thomas E. Dube
Metamorphism As A Software Protection For Non-Malicious Code, Thomas E. Dube
Theses and Dissertations
Most organizations are aware that threats from trusted insiders pose a great risk to their organization and are very difficult to protect against. Auditing is recognized as an effective technique to detect malicious insider activities. However, current auditing methods are typically applied with a one-size-fits-all approach and may not be an appropriate mitigation strategy, especially towards insider threats. This research develops a 4-step methodology for designing a customized auditing template for a Microsoft Windows XP operating system. Two tailoring methods are presented which evaluate both by category and by configuration. Also developed are various metrics and weighting factors as a …
A Real-Time Wireless Sensor Media Access Control (Mac) Protocol, Barry W. Park
A Real-Time Wireless Sensor Media Access Control (Mac) Protocol, Barry W. Park
Theses and Dissertations
Wireless sensor networks are rapidly becoming a platform for applications such as battlefield monitoring, intelligence gathering, environmental monitoring, and emergency response. Inherent in these applications is a priority and urgency of the information or messages. This means the messages must be delivered in a timely manner for them to be useful. This research assigns a message priority level and provides high-priority messages quicker access to the channel. Using MICA2 sensors and a modified Media Access Control (MAC) layer, real-time message End-to-End (ETE) delay was reduced by 50 percent. Coupled with this decrease in delay, these same real-time messages also had …
Polar Phase Screens: A Comparison With Other Methods Of Random Phase Screen Generation, Rebecca J. Eckert
Polar Phase Screens: A Comparison With Other Methods Of Random Phase Screen Generation, Rebecca J. Eckert
Theses and Dissertations
This research provides the first organized comparison of random phase screen generation methods, including logarithmic polar Fourier series, using structure functions. Random phase screens are essential elements of simulating light propagation through turbulent media. In order to be effective, they must accurately reflect theory and be practical to implement. This research explains and evaluates three methods of generating random phase screens: using a Fourier series upon a polar frequency grid with logarithmic spacing; using the fast Fourier transform, with its Cartesian frequency grid; and using Zernike polynomials. It provides a comparison of the Polar Fourier Series technique with the two …
Toward The Static Detection Of Deadlock In Java Software, Jose E. Fadul
Toward The Static Detection Of Deadlock In Java Software, Jose E. Fadul
Theses and Dissertations
Concurrency is the source of many real-world software reliability and security problems. Concurrency defects are difficult to detect because they defy conventional software testing techniques due to their non-local and non-deterministic nature. We focus on one important aspect of this problem: static detection of the possibility of deadlock - a situation in which two or more processes are prevented from continuing while each waits for resources to be freed by the continuation of the other. This thesis proposes a flow-insensitive interprocedural static analysis that detects the possibility that a program can deadlock at runtime. Our analysis proceeds in two steps. …
Air Gap Error Compensation For Coaxial Transmission Line Method Of Electromagnetic Material Characterization, Ronald G. Fehlen
Air Gap Error Compensation For Coaxial Transmission Line Method Of Electromagnetic Material Characterization, Ronald G. Fehlen
Theses and Dissertations
This research analyzes material characterization measurements from 50 Mhz to 3.05 GHz where an axially symmetric air gap exists between the sample material and the inner or outer conductor. Higher order fields are excited by the air gap and are accounted for through modal analysis methods. A root search minimizes the difference between the calculated scattering parameters from the modal method and the experimentally measured scattering parameters. The root is the permittivity and permeability of the material. This method is tested with a non-magnetic material and a heavily loaded magnetic material. An error analysis based on dimension measurement uncertainty is …
Forward-Looking Radar Clutter Suppression Using Frequency Diverse Arrays, Piotr Baizert
Forward-Looking Radar Clutter Suppression Using Frequency Diverse Arrays, Piotr Baizert
Theses and Dissertations
This thesis introduces a new array structure, the Frequency Diverse Array (FDA), where each channel transmits and receives at a different frequency. The resulting range-dependent FDA antenna pattern is proposed to improve forward-looking clutter suppression. The planar FDA radar data model is derived and analytically verified to be equivalent to the constant frequency data model when each element frequency is set to the same value. The linear FDA at high platform altitude provides significant benefits? by reducing the range ambiguous clutter contribution, improving target detection by up to 10 dB. At low altitudes without range ambiguous clutter the linear FDA …
Development Of A Wireless Model Incorporating Large-Scale Fading In A Rural, Urban And Suburban Environment, Roger A. Illari
Development Of A Wireless Model Incorporating Large-Scale Fading In A Rural, Urban And Suburban Environment, Roger A. Illari
Theses and Dissertations
The goal of this research is to develop a more realistic estimate of received signal strength level as calculated by OPNET. The goal is accomplished by replacing the existing free-space pathloss model used by OPNET with the Hata and COST-231 pathloss models. The calculated received signal strength using the new models behaves similarly to the measured values, with a 0.245 dB difference for 880 MHz and a 1.365 dB difference for 1922 MHz between the pathloss slopes. There is an 11.3 dBm difference between the initial starting signal strength from the calculated values and the measured values. An important aspect …
Speech Recognition Using The Mellin Transform, Jesse R. Hornback
Speech Recognition Using The Mellin Transform, Jesse R. Hornback
Theses and Dissertations
The purpose of this research was to improve performance in speech recognition. Specifically, a new approach was investigating by applying an integral transform known as the Mellin transform (MT) on the output of an auditory model to improve the recognition rate of phonemes through the scale-invariance property of the Mellin transform. Scale-invariance means that as a time-domain signal is subjected to dilations, the distribution of the signal in the MT domain remains unaffected. An auditory model was used to transform speech waveforms into images representing how the brain "sees" a sound. The MT was applied and features were extracted. The …
Comparison Of Computational Electromagnetic Codes For Prediction Of Low-Frequency Radar Cross Section, Paul C. Lash
Comparison Of Computational Electromagnetic Codes For Prediction Of Low-Frequency Radar Cross Section, Paul C. Lash
Theses and Dissertations
Radar cross section (RCS) prediction of full-scale aircraft is of interest to military planners for a variety of applications. Several computational electromagnetic codes for RCS prediction are available with differing features and capabilities. The goal of this research is to compare the capabilities of three computational electromagnetic codes for use in production of RCS signature assessments at low frequencies in terms of performance, accuracy, and features: Fast Illinois Solver Code (FISC), Code for Analysis of Radiators on Lossy Surfaces (CARLOS-3D), and Science Applications International Corporation Full-wave solver (SAF). The comparison is accomplished through analysis of predicted and measured RCS of …
Multiple Model Methods For Cost Function Based Multiple Hypothesis Trackers, Matthew C. Kozak
Multiple Model Methods For Cost Function Based Multiple Hypothesis Trackers, Matthew C. Kozak
Theses and Dissertations
Multiple hypothesis trackers (MHTs) are widely accepted as the best means of tracking targets in clutter. This research seeks to incorporate multiple model Kalman filters into an Integral Square Error (ISE) cost-function-based MHT to increase the fidelity of target state estimation. Results indicate that the proposed multiple model methods can properly identify the maneuver mode of a target in dense clutter and ensure that an appropriately tuned filter is used. During benign portions of flight, this causes significant reductions in position and velocity RMS errors compared to a single-filter MHT. During portions of flight when the mixture mean deviates significantly …
Side-Looking Airborne Adaptive Operation In Hot Clutter, Timothy W. Lawson
Side-Looking Airborne Adaptive Operation In Hot Clutter, Timothy W. Lawson
Theses and Dissertations
This research effort examines side-looking airborne radar operation in hot clutter. In this context, hot clutter is an electronic counter-measure used to degrade airborne radar performance. Hot clutter occurs by illuminating the ground with an airborne jammer at some velocity, azimuth, elevation, and range from the airborne radar. This research uses a simplifying assumption where the bistatic hot clutter radar cross section (RCS) scattering statistics are identical to the monostatic clutter RCS scattering statistics. When the airborne jammer waveform scattered returns are perfectly coherent with the radar waveform, the radar cannot distinguish between the returns transmitted by the jammer and …
Decision Directed And Constant Modulus Algorithms Derived And Evaluated For Multicarrier Systems, Nicholas L. Linnenkamp
Decision Directed And Constant Modulus Algorithms Derived And Evaluated For Multicarrier Systems, Nicholas L. Linnenkamp
Theses and Dissertations
The purpose of this research is to derive and examine blind adaptive algorithms for equalizing multicarrier (MC) communication systems. The author analyzes how they perform under varying environmental conditions and parametric variations, focusing on equalizers set in cascade with the channel. Two well-accepted and widely known cost functions, Decision Directed (DD) and Constant Modulus (CM), are applied to the MC signal structure, and gradient descent algorithms based on both DD and CM functions are derived, analyzed, and compared. Comparison of the new algorithms, Multi-Carrier Decision Directed (MCDD) and Multi-Carrier Constant Modulus (MCCM), focuses on detailing how each algorithm performs when …