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Modeling Of Sbs Phase Conjugation In Multimode Step Index Fibers, Justin B. Spring
Modeling Of Sbs Phase Conjugation In Multimode Step Index Fibers, Justin B. Spring
Theses and Dissertations
Stimulated Brillouin scattering in a multimode step-index fiber can be used to generate a counter-propagating, phase-conjugate beam that would prove useful in many applications, such as near diffraction limited, double-pass high-power amplifiers or coherent beam combination. Relatively little modeling of such a fiber-based phase conjugator has been done, making design decisions regarding type and length of fiber largely guesswork. A numerical model was constructed with the aim of providing educated predictions about the phase conjugate fidelity that could be expected from a given pump intensity input coupled into a specific fiber. A numerical perturbation algorithm was constructed to search for …
Evaluating Experiential Leader Development: A Programmatic Of The Effectiveness Of Us Air Force Squadron Officer School Curricula, Jeffrey G. Holland
Evaluating Experiential Leader Development: A Programmatic Of The Effectiveness Of Us Air Force Squadron Officer School Curricula, Jeffrey G. Holland
Theses and Dissertations
Leader development programs often employ experiential learning exercises. The impact of such exercises is not clear. This research investigated experiential leader development using a quasi-experimental design to analyze the differences in two consecutive US Air Force Squadron Officer School (SOS) in-residence classes. The curriculum was altered between classes by the addition of the Combat Leadership Exercise (CLX), an experiential war-gaming activity. Experiential programs regularly use mean differences between pretest and posttest measurements to represent program impact. However, research shows that participants may change the way they evaluate themselves between test administrations due to their experiences in the programs, a phenomenon …
Determination Of Static And Dynamic Stability Derivatives Using Beggar, Michael E. Bartowitz
Determination Of Static And Dynamic Stability Derivatives Using Beggar, Michael E. Bartowitz
Theses and Dissertations
The static and dynamic pitch and roll stability derivatives of a finned, axisymmetric missile known as the Basic Finner were examined using a Computational Fluid Dynamics (CFD) approach. Stability derivatives are used to characterize vehicle motion, and knowledge of them is critical to the design of stable uncontrolled vehicles and control systems for controlled vehicles. Using CFD to characterize the motion of new munition designs has the potential to improve overall performance and reduce research and testing costs. The present analysis simulated forced oscillation and free oscillation of the Basic Finner model using the Air Force SEEK EAGLE Office's Beggar …
Demonstrative Maneuvers For Aircraft Agility Predictions, David M. Hall
Demonstrative Maneuvers For Aircraft Agility Predictions, David M. Hall
Theses and Dissertations
This study was motivated by a need to develop a reliable method of predicting the agility characteristics of various aircraft. To fully investigate the agility of an aircraft, maneuvers which push the limits of an aircraft’s maneuvering capabilities must be simulated. In these cases, classic trajectory optimization techniques either require too many assumptions for a realistic solution or require a good guess of the final solution before the problem is even attempted. This study investigated both the utility of pseudospectral optimization methods for robust trajectory optimization as well as the potential for demonstrating differences in aircraft agility characteristics of several …
Direct Initiation Through Detonation Branching In A Pulsed Detonation Engine, Alexander R. Hausman
Direct Initiation Through Detonation Branching In A Pulsed Detonation Engine, Alexander R. Hausman
Theses and Dissertations
Pulsed Detonation Engines are currently limited in operating frequency to the order of 40 Hz due to lengthy ignition and deflagration to detonation transition (DDT) times. An experimental study is conducted to determine the requirements necessary to eliminate these constraints through the concept of direct initiation. A branched detonation crossover setup is constructed and the operational requirements are determined. This research demonstrates the ability to directly initiate a detonation in a vacant tube from a detonation obtained through detonation branching. Using a hydrogen-air mixture, a tail-to-head detonation branching is achieved in which a detonation is seen to propagate from a …
Uncorrelated Track Avoidance, Darrell L. Grob
Uncorrelated Track Avoidance, Darrell L. Grob
Theses and Dissertations
The purpose of this thesis is to examine what data requirements are necessary to avoid continual series of uncorrelated tracks when gathering observations. The constants of the motion for simple two-body motion for a satellite orbiting the Earth, known as the classical orbital elements or COEs, do not remain constant due to zonal and sectoral harmonic variations in the Earth’s gravitational field. There are other elements of the motion that should be considered and this paper discusses the constancy of three elements: the Hamiltonian (H) of the Earth-Centered Rotating System, Ẑ-component of inertial angular momentum (Hk), …
Initial Determination Of Low Earth Orbits Using Commercial Telescopes, Matthew M. Schmunk
Initial Determination Of Low Earth Orbits Using Commercial Telescopes, Matthew M. Schmunk
Theses and Dissertations
Within the last decade, many new technologies have significantly changed the face of private astronomy. Developments such as inexpensive but high-quality sensors, rapid personal computing, and easy networking inspire a reexamination of an old problem: how practical is it to develop initial orbit estimates for Low Earth Orbiting (LEO) satellites using optical tracking? This paper documents the design and implementation of a commercial telescope system used to answer precisely that question. This analysis deter- mined there are some challenging barriers to successful single-site orbit determination, but it is possible given the right conditions. Considering the low cost and small sup- …
Determining The Capability Requirements For A Space Based Optical Sensor To Determine The Trajectory Of An Incoming Antisatellite Weapon, Mesut Gulmus
Theses and Dissertations
The goal of this research is to build up a logic to catch and track incoming ASAT weapons by using space-based onboard optical sensors. The satellite orbit and ASAT trajectory of the Chinese test were generated to relate the research to the real world application. These position and velocity values are used to generate simulated observation data for a hypothetical sensor on the targeted satellite. These observation values are assumed to be true, and some representative amounts of error was added to these data. Only two body dynamics are considered; drag effect and other perturbations are neglected. The modern orbit …
A Multi-Objective Linear Program Model To Test Hub-And-Spoke Networks As A Potential Air Force Deployment Alternative, Andrew J. Cullen
A Multi-Objective Linear Program Model To Test Hub-And-Spoke Networks As A Potential Air Force Deployment Alternative, Andrew J. Cullen
Theses and Dissertations
The purpose of this research is to develop a multiple-objective mixed-integer linear programming model that determines the feasibility of a new deployment paradigm, which offers greater flexibility to home station and deployed location civil engineers (CE) by applying hub-and-spoke networking. The research covers the histories of CE and Air and Space Expeditionary Force (AEF), current CE deployment needs, multiple-objective decision analysis, hub-and-spoke networking, and organizational behavior benefits of the new paradigm. The methodology section provides details on each objective, explains the model, defines weights, and explains the objective function’s calculation. Next, an analysis of the model’s resulting scenarios helps determine …
An Examination Into How Group Performance Is Influenced By Various Communication Channels, Jason C. Norgaard
An Examination Into How Group Performance Is Influenced By Various Communication Channels, Jason C. Norgaard
Theses and Dissertations
This purpose of this research was to look at the how group performance is influenced by various communication channels. Specifically, this research sought to determine what communication factors are affected when groups are forced to use different communications channels. The three communications channels tested were face-to-face communications, audio conferencing, and computer-mediated communications through an Internet chat program. Each channel was measured on accuracy, efficiency, and total number of ideas generated. The research found that the groups using computer-mediated communications had a difficult time completing the exercises in the allotted time. Additionally, the computer-mediated produced significantly fewer total words and total …
Piv-Based Examination Of Deep Stall On An Oscillating Air Foil, Daniel E. Fredberg
Piv-Based Examination Of Deep Stall On An Oscillating Air Foil, Daniel E. Fredberg
Theses and Dissertations
A number of studies suggest that the deep stall flow fields produced by a pure-pitch and a pure-plunge oscillating airfoil are equivalent, when effective angles of attack are matched. This assumption is examined using particle image velocimetry (PIV). Sinusoidal oscillations of a pure-plunge and pure-pitch airfoil with matched reduced frequency k = 3.93 and with kinematically equivalent amplitudes of effective angle of attack are comparatively examined using results of PIV in a free surface water tunnel at AFRL/RB, Wright Patterson AFB. Experiments were conducted at Re = 10,000 and Re = 40,000, based on free stream velocity and airfoil chord, …
Mining Association Rules Between Credits In The Leadership In Energy And Environmental Design For New Construction (Leed-Nc) Green Building Assessment System, Benjamin J. Thomas
Mining Association Rules Between Credits In The Leadership In Energy And Environmental Design For New Construction (Leed-Nc) Green Building Assessment System, Benjamin J. Thomas
Theses and Dissertations
The Leadership in Energy and Environmental Design (LEED) Building Assessment System is a performance-based tool for determining the environmental impact of a facility from the whole-building perspective. Taking this vision into account, the individual credits that comprise LEED are designed to reward design teams for employing sustainable design strategies that reduce the total environmental impact across several sustainability issues. This study analyzed projects that have been certified in LEED for New Construction (LEED-NC) versions 2.0 and 2.1. Data on the credits achieved by the projects were mined using the Apriori algorithm which produced 641 association rules. These results were then …
Composable Distributed Access Control And Integrity Policies For Query-Based Wireless Sensor Networks, David W. Marsh
Composable Distributed Access Control And Integrity Policies For Query-Based Wireless Sensor Networks, David W. Marsh
Theses and Dissertations
An expected requirement of wireless sensor networks (WSN) is the support of a vast number of users while permitting limited access privileges. While WSN nodes have severe resource constraints, WSNs will need to restrict access to data, enforcing security policies to protect data within WSNs. To date, WSN security has largely been based on encryption and authentication schemes. WSN Authorization Specification Language (WASL) is specified and implemented using tools coded in JavaTM. WASL is a mechanism{independent policy language that can specify arbitrary, composable security policies. The construction, hybridization, and composition of well{known security models is demonstrated and shown to preserve …
Extending Cfd Modeling To Near-Continuum Flows Using Enhanced Thermophysical Modeling, Abram E. Claycomb
Extending Cfd Modeling To Near-Continuum Flows Using Enhanced Thermophysical Modeling, Abram E. Claycomb
Theses and Dissertations
The constitutive relations found in traditional Navier-Stokes-based computational fluid dynamics solvers are known to be limited in altitude. The presence of nonequilibrium phenomena beyond what these methods are able to predict becomes more prevalent at higher altitudes, or increasing Knudsen number. The bulk viscosity, normally assumed to be zero in most computational fluid dynamics applications, is examined as a means of increasing the range of applicability of computational fluid dynamics. The bulk viscosity model used was from recent calculations available in the literature, from a new anisotropic potential energy surface, and is restricted to temperatures below 2000 K. The normal …
Modulation Response Of Twin Optically Coupled Diode Lasers, Eric M. Golden
Modulation Response Of Twin Optically Coupled Diode Lasers, Eric M. Golden
Theses and Dissertations
Diode lasers are useful in military and commercial applications that have strict requirements for size, weight and power. This includes the use of diode lasers in optoelectronic and photonic integrated circuits, which can lead to new technologies in optical communications and optical interconnects in high performance computing systems. For these systems to be effective, the diode laser must be modulated at frequencies beyond current limits which are typically a few GHz. This barrier can be broken by optically coupling a diode laser with a similar laser. A set of single mode rate equations models the dynamics of twin optically coupled …
A Formal Specification And Proof Of System Safety Using The Schematic Protection Model, Raymond S. Way
A Formal Specification And Proof Of System Safety Using The Schematic Protection Model, Raymond S. Way
Theses and Dissertations
This research formally specifies the Schematic Protection Model (SPM) and provides a sound, flexible tool for reasoning formally about systems that implement a security model like SPM, to prove its ability to provide security services such as confidentiality and integrity. The theory described by the resultant model was logically proved in the Prototype Verification System (PVS), an automated prover. Each component of SPM was tested, as were several anomalous conditions, and each test produced results consistent with the model. The model is internally modular, and therefore easily extensible, yet cohesive since the theory to be proved encompasses the entire specification. …
An Analysis Of Groundwater Flow Patterns In A Constructed Treatment Wetland Cell, Rebecca S. Corbin
An Analysis Of Groundwater Flow Patterns In A Constructed Treatment Wetland Cell, Rebecca S. Corbin
Theses and Dissertations
This research effort analyzed groundwater flow paths within a treatment wetland constructed to degrade tetrachloroethylene (PCE) in groundwater. The treatment cell is a vertical flow wetland that allows the water to flow from the bottom to the surface breaking down PCE and daughter products. The method of conducting this research included collecting field data of hydraulic head contours nested piezometers and collecting data from sampling wells to determine hydraulic conductivities in the wetland. The field data was used to create a numerical computer model to determine groundwater flow patterns. The field data and the model demonstrate that there are areas …
Damage Detection Analysis Using Lamb Waves In Restricted Geometry For Aerospace Applications, Roman T. Underwood
Damage Detection Analysis Using Lamb Waves In Restricted Geometry For Aerospace Applications, Roman T. Underwood
Theses and Dissertations
Today many USAF aircraft are approaching the end of their projected service life. However, those aircraft, such as the F-15 Eagle, are still being operated to accomplish the mission of the USAF. As the F-15 ages the required maintenance increases, as does the risk of structural failure. A goal of structural health monitoring (SHM) programs is to increase aircraft safety by monitoring areas known to have structural failures. Currently, time intensive manual inspections are used to monitor failure “hotspots” decreasing the readiness of the F-15 fleet. The lead ziconate titanate (PZT) is a commonly used piezoelectric transducer that has shown …
Dialable Cryptography For Wireless Networks, Marnita T. Eaddie
Dialable Cryptography For Wireless Networks, Marnita T. Eaddie
Theses and Dissertations
The objective of this research is to develop an adaptive cryptographic protocol, which allows users to select an optimal cryptographic strength and algorithm based upon the hardware and bandwidth available and allows users to reason about the level of security versus the system throughput. In this constantly technically-improving society, the ability to communicate via wireless technology provides an avenue for delivering information at anytime nearly anywhere. Sensitive or classified information can be transferred wirelessly across unsecured channels by using cryptographic algorithms. The research presented will focus on dynamically selecting optimal cryptographic algorithms and cryptographic strengths based upon the hardware and …
A Hybrid Communications Network Simulation-Independent Toolkit, David M. Dines
A Hybrid Communications Network Simulation-Independent Toolkit, David M. Dines
Theses and Dissertations
Net-centric warfare requires information superiority to enable decision superiority, culminating in insurmountable combat power against our enemies on the battlefield. Information superiority must be attained and retained for success in today’s joint/coalition battlespace. To accomplish this goal, our combat networks must reliably, expediently and completely deliver over a wide range of mobile and fixed assets. Furthermore, each asset must be given special consideration for the sensitivity, priority and volume of information required by the mission. Evolving a grand design of the enabling network will require a flexible evaluation platform to try and select the right combination of network strategies and …
Multi-Objective Uav Mission Planning Using Evolutionary Computation, Adam J. Pohl
Multi-Objective Uav Mission Planning Using Evolutionary Computation, Adam J. Pohl
Theses and Dissertations
This investigation purports to develop a new model for multiple autonomous aircraft mission routing. Previous research both related and unrelated to this endeavor have used classic combinatoric problems as models for Unmanned Aerial Vehicle (UAV) routing and mission planning. This document presents the concept of the Swarm Routing Problem (SRP) as a new combinatorics problem for use in modeling UAV swarm routing, developed as a variant of the Vehicle Routing Problem with Time Windows (VRPTW). The SRP removes the single vehicle per target restraint and changes the customer satisfaction requirement to one of vehicle on location volume. The impact of …
Developing A Reference Framework For Cybercraft Trust Evaluation, Shannon E. Hunt
Developing A Reference Framework For Cybercraft Trust Evaluation, Shannon E. Hunt
Theses and Dissertations
It should be no surprise that Department of Defense (DoD) and U.S. Air Force (USAF) networks are the target of constant attack. As a result, network defense remains a high priority for cyber warriors. On the technical side, trust issues for a comprehensive end-to-end network defense solution are abundant and involve multiple layers of complexity. The Air Force Research Labs (AFRL) is currently investigating the feasibility of a holistic approach to network defense, called Cybercraft. We envision Cybercraft to be trusted computer entities that cooperate with other Cybercraft to provide autonomous and responsive network defense services. A top research goal …
Increasing Combat Aircraft Survivability Through Coherent Self-Protection Jammers, Soner Ozer
Increasing Combat Aircraft Survivability Through Coherent Self-Protection Jammers, Soner Ozer
Theses and Dissertations
When the battlefields were within the visual range, the objective of deception tactics in warfare was to deceive the human senses. In the battlefield of electromagnetic spectrum, the objective of deception is to deceive the sensors of the enemy weapon systems. The survivability of the aircraft operating in hostile environment is of prime importance to the mission planner. If the aircraft can deny its location information to the tracking radar of the radar guided threat missile system, this, in return, may increase its survivability. The deception, a tactic which stems from the wisdom of ancient battles, incarnated in the form …
Feasibility Study Of Encoding Operational Mission Metadata Into Ipv6 Packet Headers, Timothy R. Policarpio
Feasibility Study Of Encoding Operational Mission Metadata Into Ipv6 Packet Headers, Timothy R. Policarpio
Theses and Dissertations
The purpose of this research is to determine the feasibility of using the header fields and header extensions of IPv6 packets to encode mission metadata into computer network streams. Specifically, this thesis seeks to answer several research questions addressing the performance of different packet header encoding methods, specifically which method provides the least end-to-end delay of a file transfer over a hypothetical network as well as which method produces the least amount of additional network overhead during its operation in the hypothetical network. The research questions are answered through a comprehensive literature review and with the use of several network …
Microfluidic Power Generation, Aaron J. Sprecher
Microfluidic Power Generation, Aaron J. Sprecher
Theses and Dissertations
This thesis includes the detailed mathematical calculations used to determine the feasibility of harnessing electrical energy from the blood flow through human capillaries. The designs are inspired by human physiology and well established electromagnetic energy harvesting techniques and the fabrication methods have been proposed for the various components of the device. The fabrication and the design of these components have also been extensively analyzed using calculations based on the governing principles of microfluidics, kinetics, and electromagnetics. The analysis has confirmed that this design can produce sufficient energy to power a MEMS device using non-standard materials and fabrication methods. The designs …
Establishing The Human Firewall: Reducing An Individual's Vulnerability To Social Engineering Attacks, Jamison W. Scheeres
Establishing The Human Firewall: Reducing An Individual's Vulnerability To Social Engineering Attacks, Jamison W. Scheeres
Theses and Dissertations
Hackers frequently use social engineering attacks to gain a foothold into a target network. This type of attack is a tremendous challenge to defend against, as the weakness lies in the human users, not in the technology. Thus far, methods for dealing with this threat have included establishing better security policies and educating users on the threat that exists. Existing techniques aren’t working as evidenced by the fact that auditing agencies consider it a given that will be able to gain access via social engineering. The purpose of this research is to propose a better method of reducing an individual’s …
Behavior-Based Power Management In Autonomous Mobile Robots, Charles A. Fetzek
Behavior-Based Power Management In Autonomous Mobile Robots, Charles A. Fetzek
Theses and Dissertations
Current attempts to prolong the life of a robot on a single battery charge focus on lowering the operating frequency of the onboard hardware, or allowing devices to go to sleep during idle states. These techniques have much overhead and do not come built in to the underlying robotic architecture. In this thesis, battery life is greatly extended through development of a behavior-based power management system, including a Markov decision process power planner, thereby allowing future robots increased time to operate and loiter in their required domain. Behavior-based power management examines sensors needed by the currently active behavior set and …
Improvement Of Ecm Techniques Through Implementation Of A Genetic Algorithm, James D. Townsend
Improvement Of Ecm Techniques Through Implementation Of A Genetic Algorithm, James D. Townsend
Theses and Dissertations
This research effective effort develops the necessary interfaces between the radar signal processing components and an optimization routine, such as genetic algorithms, to develop Electronic Countermeasure (ECM) waveforms under a Hardware-in-the-Loop (HILS) architecture. The various ECM waveforms are stored in an ECM library, where an operator selects the desired function to use against a particular system. This optimization works with modular components, compared to previous research that embedded a genetic algorithm into the Range Gate Pull-off (RGPO) waveform optimization loop, which can be interchanged based upon the operator's desired hardware/ software testing setup. The ECM library's first entries contain the …
Dynamic Behavior Sequencing In A Hybrid Robot Architecture, Jeffrey P. Duffy
Dynamic Behavior Sequencing In A Hybrid Robot Architecture, Jeffrey P. Duffy
Theses and Dissertations
Hybrid robot control architectures separate plans, coordination, and actions into separate processing layers to provide deliberative and reactive functionality. This approach promotes more complex systems that perform well in goal-oriented and dynamic environments. In various architectures, the connections and contents of the functional layers are tightly coupled so system updates and changes require major changes throughout the system. This work proposes an abstract behavior representation, a dynamic behavior hierarchy generation algorithm, and an architecture design to reduce this major change incorporation process. The behavior representation provides an abstract interface for loose coupling of behavior planning and execution components. The hierarchy …
A Secure Group Communication Architecture For A Swarm Of Autonomous Unmanned Aerial Vehicles, Adrian N. Phillips
A Secure Group Communication Architecture For A Swarm Of Autonomous Unmanned Aerial Vehicles, Adrian N. Phillips
Theses and Dissertations
This thesis investigates the application of a secure group communication architecture to a swarm of autonomous unmanned aerial vehicles (UAVs). A multicast secure group communication architecture for the low earth orbit (LEO) satellite environment is evaluated to determine if it can be effectively adapted to a swarm of UAVs and provide secure, scalable, and efficient communications. The performance of the proposed security architecture is evaluated with two other commonly used architectures using a discrete event computer simulation developed using MatLab. Performance is evaluated in terms of the scalability and efficiency of the group key distribution and management scheme when the …