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Air Force Institute of Technology

Theses/Dissertations

2008

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Stimulated Brillouin Scattering Phase Conjugation In Fiber Optic Waveguides, Steven M. Massey Aug 2008

Stimulated Brillouin Scattering Phase Conjugation In Fiber Optic Waveguides, Steven M. Massey

Theses and Dissertations

The objective of this research effort was to demonstrate the path to continuous wave, coherent beam combination through stimulated Brillouin scattering phase conjugation in optical fiber. This work experimentally determined the fiber parameters necessary for phase conjugation in step-index optical fiber. Continuous wave phase conjugation using stimulated Brillouin scattering in step-index fibers was achieved for the first time with a fidelity of 0.8 and a threshold power of 16 W in a 15-m fiber with 0.13 NA. A fidelity of 0.8 was also achieved using 40 m of fiber with 0.06-NA and a threshold power of 15 W. The fidelity …


Multi-Class Classification For Identifying Jpeg Steganography Embedding Methods, Benjamin M. Rodriguez Ii Aug 2008

Multi-Class Classification For Identifying Jpeg Steganography Embedding Methods, Benjamin M. Rodriguez Ii

Theses and Dissertations

Over 725 steganography tools are available over the Internet, each providing a method for covert transmission of secret messages. This research presents four steganalysis advancements that result in an algorithm that identifies the steganalysis tool used to embed a secret message in a JPEG image file. The algorithm includes feature generation, feature preprocessing, multi-class classification and classifier fusion. The first contribution is a new feature generation method which is based on the decomposition of discrete cosine transform (DCT) coefficients used in the JPEG image encoder. The generated features are better suited to identifying discrepancies in each area of the decomposed …


Metamodeling Techniques To Aid In The Aggregation Process Of Large Hierarchical Simulation Models, June F.D. Rodriguez Aug 2008

Metamodeling Techniques To Aid In The Aggregation Process Of Large Hierarchical Simulation Models, June F.D. Rodriguez

Theses and Dissertations

This research investigates how aggregation is currently conducted for simulation of large systems. The purpose is to examine how to achieve suitable aggregation in the simulation of large systems. More specifically, investigating how to accurately aggregate hierarchical lower-level (higher resolution) models into the next higher-level in order to reduce the complexity of the overall simulation model. The focus is on the exploration of the different aggregation techniques for hierarchical lower-level (higher resolution) models into the next higher-level. We develop aggregation procedures between two simulation levels (e.g., aggregation of engagement level models into a mission level model) to address how much …


A Wide Area Bipolar Cascade Resonant Cavity Light Emitting Diode For A Hybrid Range-Intensity, Reginald J. Turner Jun 2008

A Wide Area Bipolar Cascade Resonant Cavity Light Emitting Diode For A Hybrid Range-Intensity, Reginald J. Turner

Theses and Dissertations

This dissertation focused on the development of an illuminator for the HRIS. This illuminator enables faster image rendering and reduces the potential of errors in return signal data, that could be generated from extremely rough terrain. Four major achievements resulted from this work, which advance the field of 3-D image acquisition. The first is that the TJ is an effective current spreading layer for LEDs with mesa width up to 140 micrometers and current densities of approximately 1 x 106 Amp/square centimeter. The TJ allows fabrication of an efficient illuminator, with required geometry for the HRIS to operate as …


Material Perturbations To Enhance Performance Of The Theile Half-Width Leaky Mode Antenna, Jason A. Girard Jun 2008

Material Perturbations To Enhance Performance Of The Theile Half-Width Leaky Mode Antenna, Jason A. Girard

Theses and Dissertations

Microstrip traveling-wave antennas, often referred to as leaky-wave antennas, have been shown to radiate when the dominant or fundamental mode is suppressed and the first higher-order mode is excited. One such microstrip variation is the Thiele Half-Width (THW) antenna, which operates from 5.9 - 8.2 GHz for this research. Increasing the bandwidth over which the THW antenna radiates is desired, as is a fundamental understanding of the propagation characteristics over this region. This dissertation seeks to vary or perturb the material and physical properties of the THW antenna, including strip-width variations and modifications of the substrate layer, to achieve these …


Characterizing Effects And Benefits Of Beam Defocus On High Energy Laser Performance Under Thermal Blooming And Turbulence Conditions For Air-To-Ground Engagements, Scott N. Long Jun 2008

Characterizing Effects And Benefits Of Beam Defocus On High Energy Laser Performance Under Thermal Blooming And Turbulence Conditions For Air-To-Ground Engagements, Scott N. Long

Theses and Dissertations

This dissertation makes contributions towards knowledge of optimizing of laser weapon performance when operating in the air-to-ground (ATG) regime in thermal blooming conditions. Wave optics modeling techniques were used to represent laser weapon performance in a high fidelity sense to allow progress to be made toward improving lower-fidelity scaling laws that can be used in systems level analysis which has need for better representations of thermal blooming. Chemical-oxygen iodine laser (COIL) based weapon systems that operate near the ground will experience thermal blooming due to atmospheric absorption if output power is sufficiently high. The thermal lens in the ATG case …


Hardware, Software And Data Analysis Techniques For Sram-Based Field Programmable Gate Array Circuits, Eugene B. Hockenberry Jun 2008

Hardware, Software And Data Analysis Techniques For Sram-Based Field Programmable Gate Array Circuits, Eugene B. Hockenberry

Theses and Dissertations

This work presents a built, tested, and demonstrated test structure that is low-cost, flexible, and re-usable for robust radiation experimentation, primarily to investigate memory, in this case SRAMs and SRAM-based FPGAs. The space environment can induce many kinds of failures due to radiation effects. These failures result in a loss of money, time, intelligence, and information. In order to evaluate technologies for potential failures, a detailed test methodology and associated structure are required. In this solution, an FPGA board was used as the controller platform, with multiple VHDL circuit controllers, data collection and reporting modules. The structure was demonstrated by …


Developing Network Situational Awareness Through Visualization Of Fused Intrusion Detection System Alerts, Serafin A. Avitia V Jun 2008

Developing Network Situational Awareness Through Visualization Of Fused Intrusion Detection System Alerts, Serafin A. Avitia V

Theses and Dissertations

With networks increasing in physical size, bandwidth, traffic volume, and malicious activity, network analysts are experiencing greater difficulty in developing network situational awareness. Traditionally, network analysts have used Intrusion Detection Systems to gain awareness but this method is outdated when analysts are unable to process the alerts at the rate they are being generated. Analysts are unwittingly placing the computer assets they are charged to protect at risk when they are unable to detect these network attacks. This research effort examines the theory, application, and results of using visualizations of fused alert data to develop network situational awareness. The fused …


The Effect Of Radiation On The Electrical Properties Of Aluminum Gallium Nitride/Gallium Nitride Heterostructures, John W. Mcclory Jun 2008

The Effect Of Radiation On The Electrical Properties Of Aluminum Gallium Nitride/Gallium Nitride Heterostructures, John W. Mcclory

Theses and Dissertations

AlGaN/GaN Heterojunction Field Effect Transistors (HFETs) were irradiated at low temperature and the temperature dependent changes to drain current, gate current, capacitance, and transconductance were measured. The results were compared to the charge control model of the drain current and trap-assisted tunneling model of the gate current to determine the source of the radiation-induced changes. AlGaN/GaN HFETs demonstrated threshold voltage shifts and drain current changes after irradiation. After electron and neutron irradiation applied at ~80 K, measurement of the drain current at this temperature showed an increase that saturated after 1013 electrons/cm2 or 1010 neutrons/cm2 due …


A Secure And Efficient Communications Architecture For Global Information Grid Users Via Cooperating Space Assets, Victor P. Hubenko Jun 2008

A Secure And Efficient Communications Architecture For Global Information Grid Users Via Cooperating Space Assets, Victor P. Hubenko

Theses and Dissertations

With the Information Age in full and rapid development, users expect to have global, seamless, ubiquitous, secure, and efficient communications capable of providing access to real-time applications and collaboration. The United States Department of Defense’s (DoD) Network-Centric Enterprise Services initiative, along with the notion of pushing the “power to the edge,” aims to provide end-users with maximum situational awareness, a comprehensive view of the battlespace, all within a secure networking environment. Building from previous AFIT research efforts, this research developed a novel security framework architecture to address the lack of efficient and scalable secure multicasting in the low earth orbit …


A Qualitative And Quantitative Assessment Of Readiness For Organizational Change Literature, Andrew B. Burris Jun 2008

A Qualitative And Quantitative Assessment Of Readiness For Organizational Change Literature, Andrew B. Burris

Theses and Dissertations

The purpose of this thesis is to take a step in integrating the change literature and accumulate the empirical results using meta-analytic techniques. First, a literature review of existing research on organizational change was conducted. Second, existing models of organizational change were integrated to create a theoretical structure. Third, a meta-analysis was performed to derive the corrected correlation values for each relationship in that structure. Finally, the readiness for change literature was qualitatively assessed. In addition, a quantitative review was done by accumulating the results across 25 studies in an effort to provide a current quantitative assessment of change management …


Laser-Induced Fluorescence And Performance Analysis Of The Ultra-Compact Combustor, Patrick J. Lakusta Jun 2008

Laser-Induced Fluorescence And Performance Analysis Of The Ultra-Compact Combustor, Patrick J. Lakusta

Theses and Dissertations

The AFIT Combustion Optimization and Analysis Laser (COAL) lab’s modular design and state-of-the-art diagnostic systems make it a flexible and important facility for the analysis of combustion processes. The objectives of the current research are to install several enhancements in the lab, validate the laser diagnostic system, characterize the igniter for AFIT’s Ultra-Compact Combustor (UCC) sections, and perform a non-intrusive laser diagnostic, performance, and high-speed video analysis of a flat-cavity UCC section. Validation of the laser system was accomplished using OH Planar Laser-Induced Fluorescence (PLIF) in a laminar hydrogen-air flame produced by a Hencken burner. Results are compared to previous …


Statistical Methods For Image Registration And Denoising, Matthew D. Sambora Jun 2008

Statistical Methods For Image Registration And Denoising, Matthew D. Sambora

Theses and Dissertations

This dissertation describes research into image processing techniques that enhance military operational and support activities. The research extends existing work on image registration by introducing a novel method that exploits local correlations to improve the performance of projection-based image registration algorithms. The dissertation also extends the bounds on image registration performance for both projection-based and full-frame image registration algorithms and extends the Barankin bound from the one-dimensional case to the problem of two-dimensional image registration. It is demonstrated that in some instances, the Cramer-Rao lower bound is an overly-optimistic predictor of image registration performance and that under some conditions, the …


An Analysis Of Botnet Vulnerabilities, Sean W. Hudson Jun 2008

An Analysis Of Botnet Vulnerabilities, Sean W. Hudson

Theses and Dissertations

Botnets are a significant threat to computer networks and data stored on networked computers. The ability to inhibit communication between servers controlling the botnet and individual hosts would be an effective countermeasure. The objective of this research was to find vulnerabilities in Unreal IRCd that could be used to shut down the server. Analysis revealed that Unreal IRCd is a very mature and stable IRC server and no significant vulnerabilities were found. While this research does not eliminate the possibility that a critical vulnerability is present in the Unreal IRCd software, none were identified during this effort.


Time-Frequency Analysis Of Terahertz Radar Signals For Rapit Heart And Breath Rate Detection, Melody L. Massar Jun 2008

Time-Frequency Analysis Of Terahertz Radar Signals For Rapit Heart And Breath Rate Detection, Melody L. Massar

Theses and Dissertations

We develop new time-frequency analytic techniques which facilitate the rapid detection of a person's heart and breath rates from the Doppler shift the movement of their body induces in a terahertz radar signal. In particular, the Doppler shift in the continuous radar return is proportional to the velocity of the person's body. Thus, a time-frequency analysis of the radar return will yield a velocity signal. This signal, in turn, may undergo a second time-frequency analysis to yield any periodic components of the velocity signal, which are often related to the heart and breath rates of the individual. One straightforward means …


Heat Transfer Due To Unsteady Effects As Investigated In A High-Speed, Full-Scale, Fully-Cooled Turbine Vane And Rotor Stage, Jonathan R. Mason Jun 2008

Heat Transfer Due To Unsteady Effects As Investigated In A High-Speed, Full-Scale, Fully-Cooled Turbine Vane And Rotor Stage, Jonathan R. Mason

Theses and Dissertations

Experiments were conducted to examine the effects of film cooling on a gas turbine engine’s high‐pressure turbine section. The focus for this effort was in the tip/shroud region of a rotor stage and a high pressure turbine vane. A primary goal was to understand the unsteady flow effects. Attempts were also made to characterize the effects as caused by the fully‐cooled rotor stage. Data for this investigation was taken at the U.S. Air Force’s Turbine Research Facility (TRF), a transient blowdown facility with instrumentation fitted to a full‐scale, high‐speed, fully‐cooled vane and rotor stage of proprietary design. Measurements of pressure, …


Developing A Decision Model For Joint Improvised Explosive Device Defeat Organization (Jieddo) Proposal Selection, Lyle M. Dawley, Lenore A. Marentee, Alice Marie Long Jun 2008

Developing A Decision Model For Joint Improvised Explosive Device Defeat Organization (Jieddo) Proposal Selection, Lyle M. Dawley, Lenore A. Marentee, Alice Marie Long

Theses and Dissertations

This research uses decision analysis to develop a structured, repeatable and most importantly defensible decision model for the evaluation of proposed IED defeat solutions submitted to the Joint IED Defeat Organization (JIEDDO). Additive value models using Value-Focused Thinking (VFT) and the Analytic Hierarchy Process (AHP) are examined as possible methodologies. VFT is determined to be the "best fit" for JIEDDO's decision situation in which proposals are submitted continuously and must be scored independently of previous proposals. VFT is first used to determine desirable qualities in IED defeat options, and then to generate a hierarchal value model to evaluate these qualities …


Fuel Composition Analysis Of Endothermically Heated Jp-8 Fuel For Use In A Pulse Detonation Engine, Eric A. Nagley Jun 2008

Fuel Composition Analysis Of Endothermically Heated Jp-8 Fuel For Use In A Pulse Detonation Engine, Eric A. Nagley

Theses and Dissertations

Waste heat from a pulse detonation engine (PDE) was extracted via zeolite catalyst coated concentric tube-counter flow heat exchangers to produce supercritical pyrolytic conditions for JP-8 fuel. A sampling system and method were developed that enabled samples of reacted fuel to be extracted during steady state operation. Samples were taken over a range of heat exchanger exit temperatures from 820 K (1016° F) to 940 K (1232° F). Offline analysis of liquid and vapor fuel samples indicated fuel decomposition via typical pyrolytic reaction pathways. The liquid analysis showed conversion of parent fuel components with formation of unsaturates (aromatics and alkenes) …


Operationally Responsive Space (Ors): An Architecture And Enterprise Model For Adaptive Integration, Test And Logistics, Jeff A. Alexander, Martha Charles-Vickers, Talbot L. Smith, Michael L. Vickers Jun 2008

Operationally Responsive Space (Ors): An Architecture And Enterprise Model For Adaptive Integration, Test And Logistics, Jeff A. Alexander, Martha Charles-Vickers, Talbot L. Smith, Michael L. Vickers

Theses and Dissertations

The capability to rapidly deploy tactical satellites to meet a Joint Force Commander's immediate battlespace requirements is a well-documented joint capability need. Key U.S. strategic documentation cites the need for the capability to maintain persistent surveillance or an "unblinking eye" over battlespace and to rapidly reconstitute critical space capabilities to preserve situational awareness. The warfighter requires a tactical space-based deployment capability which employs a request to launch and operational deployment window of 90 to 120 days. This master's thesis executed two (2) major areas of work: apply, and reinforce the Operationally Responsive Space (ORS) mission tasks using the Joint Capabilities …


Creep-Rupture And Fatigue Behavior Of A Notched Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature, Barth H. Boyer Jun 2008

Creep-Rupture And Fatigue Behavior Of A Notched Oxide/Oxide Ceramic Matrix Composite At Elevated Temperature, Barth H. Boyer

Theses and Dissertations

The inherent resistance to oxidation of oxide/oxide ceramic matrix composites makes them ideal for aerospace applications that require high temperature and long life under corrosive environments. The ceramic matrix composite (CMC) of interest in the study is the Nextel™720/Alumina (N720/A) which is comprised of an 8-harness satin weave of Nextel™ fibers embedded in an alumina matrix. One of the top applications for N720/A is in the combustion section of a turbine engine. This will require mounting and shaping the material with rivets and possibly sharp edges thereby introducing geometry based stress concentration factors. Sullivan’s research concentrated on the effects of …


Performance Analysis Of Effective Range And Orientation Of Uhf Passive Rfid, Paul N. Roque Jun 2008

Performance Analysis Of Effective Range And Orientation Of Uhf Passive Rfid, Paul N. Roque

Theses and Dissertations

The purpose of this research is to characterize the performance of UHF passive RFID tags. Factors of importance are the impact of tag orientation and distance from the RFID reader. Within this study, a comprehensive literature review of RFID technology is presented as well as the methodology used for the research. Furthermore, an analysis of RFID tag experiments is discussed and the results reviewed. To accomplish this task, two main objectives have been established as goals for the study. The first objective is to determine an optimum tag orientation within the RFID reader’s normal read range. Once the optimum tag …


Development Of A Night Vision Goggle Heads Up Display For Paratrooper Guidance, Fernando Ontiveros Jun 2008

Development Of A Night Vision Goggle Heads Up Display For Paratrooper Guidance, Fernando Ontiveros

Theses and Dissertations

This thesis provides the proof of concept for the development and implementation of a Global Positioning System (GPS) display via Night Vision Goggles (NVG) Heads-Up Display (HUD) for paratroopers. The system has been designed for soldiers who will be able to utilize the technology in the form of a processing system worn in an ammo pouch and displayed via NVG HUD as a tunnel in the sky. The tunnel in the sky display design is essentially a series of boxes displayed within the goggle's HUD leading the paratrooper to the desired Landing Zone (LZ). The algorithm developed receives GPS and …


A Case Analysis Of Explaining The Main Factors That Contribute To Rok's Decision Making In Procurement Of Defense Articles, Se Young Kim Jun 2008

A Case Analysis Of Explaining The Main Factors That Contribute To Rok's Decision Making In Procurement Of Defense Articles, Se Young Kim

Theses and Dissertations

The purpose of this research was to explore the various factors that contribute to ROK’s decision making in procurement of foreign countries defense articles. South Korea is one of the largest weapon purchasers from the U.S. and needs a more self-reliant defense force that can maintain its security with its own authority under the current cease-fire situation. Thus, this study focused on identifying the main factors to consider in deciding whether to purchase a major defense weapon system from other countries. Through the interview of experts who participated in specific weapon programs, thirteen specific factors were evaluated including Interoperability, Offset …


Optimal Control Of Electrodynamic Tethers, Robert E. Stevens Jun 2008

Optimal Control Of Electrodynamic Tethers, Robert E. Stevens

Theses and Dissertations

Low thrust propulsion systems such as electrodynamic tethers offer a fuel-efficient means to maneuver satellites to new orbits, however they can only perform such maneuvers when they are continuously operated for a long time. Such long-term maneuvers occur over many orbits often rendering short time scale trajectory optimization methods ineffective. An approach to multi-revolution, long time scale optimal control of an electrodynamic tether is investigated for a tethered satellite system in Low Earth Orbit with atmospheric drag. Control is assumed to be periodic over several orbits since under the assumptions of a nearly circular orbit, periodic control yields the only …


The Impact Of Heat Release In Turbine Film Cooling, Dave S. Evans Jun 2008

The Impact Of Heat Release In Turbine Film Cooling, Dave S. Evans

Theses and Dissertations

The Ultra Compact Combustor is a design that integrates a turbine vane into the combustor flow path. Because of the high fuel-to-air ratio and short combustor flow path, a significant potential exists for unburned fuel to enter the turbine. Using contemporary turbine cooling vane designs, the injection of oxygen-rich turbine cooling air into a combustor flow containing unburned fuel could result in heat release in the turbine and a large decrease in cooling effectiveness. The current study explores the interaction of cooling flow from typical cooling holes with the exhaust of a fuel-rich well-stirred-reactor operating at high temperatures over a …


Vibration Analysis Of Commercial Thermal Barrier Coatings, Lindell E. Pearson Jun 2008

Vibration Analysis Of Commercial Thermal Barrier Coatings, Lindell E. Pearson

Theses and Dissertations

Thermal barrier coatings (TBCs) are currently used in turbine engine components to protect substrate material from being exposed to high temperatures and corrosion. These coatings also have the potential to reduce stress in critical engine parts which could increase the life cycle of these parts. The fact that these coatings are already qualified for use in turbine engines makes it worth investigating their damping properties. The problem with TBCs is that they are difficult to characterize as they display nonlinear properties. This research utilizes an experimental and finite element procedure to characterize these coatings. A scanning electron microscope (SEM) was …


Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Benjamin T. Harder Jun 2008

Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Benjamin T. Harder

Theses and Dissertations

The United States military is exploring the use of nanocomposite materials for satellite structural applications. Current composite spacecraft structures are nonconductive and must have expensive shielding materials applied in order to protect the spacecraft from catastrophic damage that can be caused by electromagnetic interference (EMI) and/or electrostatic discharge (ESD) which are characteristics of the space environment. Conductive nanocomposites are being developed for spacecraft structures that will provide ESD and EMI shielding protection without the need for expensive secondary shielding materials. This thesis studied one such material consisting of M55J/RS-3 composite combined with nickel nanostrands™. Four different configurations were tested for …


A Survey Of Satellite Communications System Vulnerabilities, Jessica A. Steinberger Jun 2008

A Survey Of Satellite Communications System Vulnerabilities, Jessica A. Steinberger

Theses and Dissertations

The U.S. military’s increasing reliance on commercial and military communications satellites to enable widely-dispersed, mobile forces to communicate makes these space assets increasingly vulnerable to attack by adversaries. Attacks on these satellites could cause military communications to become unavailable at critical moments during a conflict. This research dissected a typical satellite communications system in order to provide an understanding of the possible attacker entry points into the system, to determine the vulnerabilities associated with each of these access points, and to analyze the possible impacts of these vulnerabilities to U.S. military operations. By understanding these vulnerabilities of U.S. communications satellite …


Mitigating Reversing Vulnerabilities In .Net Applications Using Virtualized Software Protection, Matthew A. Zimmerman Jun 2008

Mitigating Reversing Vulnerabilities In .Net Applications Using Virtualized Software Protection, Matthew A. Zimmerman

Theses and Dissertations

Protecting intellectual property contained in application source code and preventing tampering with application binaries are both major concerns for software developers. Simply by possessing an application binary, any user is able to attempt to reverse engineer valuable information or produce unanticipated execution results through tampering. As reverse engineering tools become more prevalent, and as the knowledge required to effectively use those tools decreases, applications come under increased attack from malicious users. Emerging development tools such as Microsoft's .NET Application Framework allow diverse source code composed of multiple programming languages to be integrated into a single application binary, but the potential …


Analyzing Individual Decision Making Versus Group Decision Making For Alternative Selection, Alper Gezeravci Jun 2008

Analyzing Individual Decision Making Versus Group Decision Making For Alternative Selection, Alper Gezeravci

Theses and Dissertations

Many "real world" decisions are made by groups. It is rare that the responsi- bility for a very important decision is given to a single decision maker with complete authority. Group decision making adds both advantages to the process as well as disadvantages. This research examines the question: "Are decisions made by groups really that much different from the decisions made by individuals in the group?" A specific case study involving the selection of the best primary training aircraft type for military pilot training is used to examine this question. Fifteen military pilots with various backgrounds and experience levels participate …