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Air Force Institute of Technology

2008

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Articles 31 - 60 of 95

Full-Text Articles in Physical Sciences and Mathematics

Tightly Integrating Optical And Inertial Sensors For Navigation Using The Ukf, Sedat Ebcin Mar 2008

Tightly Integrating Optical And Inertial Sensors For Navigation Using The Ukf, Sedat Ebcin

Theses and Dissertations

The motivation of this research is to address the benefits of tightly integrating optical and inertial sensors where GNSS signals are not available. The research begins with describing the navigation problem. Then, error and measurement models are presented. Given a set of features, a feature detection and projection algorithm is developed which utilizes inertial measurements to predict vectors in the feature space between images. The unscented Kalman filter is applied to the navigation system using the inertial measurements and feature matches to estimate the navigation trajectory. Finally, the image-aided navigation algorithm is tested using a simulation and an experiment. As …

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Analysis Of Non-Uniform Gain For Control Of A Deformable Mirror In An Adaptive-Optics System, Kevin P. Vitayaudom Mar 2008

Analysis Of Non-Uniform Gain For Control Of A Deformable Mirror In An Adaptive-Optics System, Kevin P. Vitayaudom

Theses and Dissertations

The Air Force Research Laboratory’s Sodium Guidestar Adaptive Optics for Space Situational Awareness program (NGAS) has sponsored research on spatially non-uniform gain for the servo-loop controller of an adaptive optics (AO) system. The edge subapertures of a Shack-Hartmann wavefront sensor have lower signal-to-noise ratios and are more susceptible to measurement errors than fully illuminated center subapertures. These measurement errors produce errant commands over the corresponding edge actuators and can induce instabilities over these regions in strong turbulence conditions. The objective of this research was to develop and experimentally verify the use of spatially varying gain maps on the servo-loop controller …

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Scramjet Fuel Injection Array Optimization Utilizing Mixed Variable Pattern Search With Kriging Surrogates, Bryan Sparkman Mar 2008

Scramjet Fuel Injection Array Optimization Utilizing Mixed Variable Pattern Search With Kriging Surrogates, Bryan Sparkman

Theses and Dissertations

Fuel-air mixing analysis of scramjet aircraft is often performed through ex- perimental research or Computational Fluid Dynamics (cfd) algorithms. Design optimization with these approaches is often impossible under a limited budget due to their high cost per run. This investigation uses jetpen, a known inexpensive analysis tool, to build upon a previous case study of scramjet design optimization. Mixed Variable Pattern Search (mvps) is compared to evolutionary algorithms in the optimization of two scramjet designs. The ¯rst revisits the previously stud- ied approach and compares the quality of mvps to prior results. The second applies mvps to a new scramjet …

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What Constitutes An Act Of War In Cyberspace, Kelli S. Kinley Mar 2008

What Constitutes An Act Of War In Cyberspace, Kelli S. Kinley

Theses and Dissertations

In December 2005 a new mission statement was released by the Air Force Leadership, "to deliver sovereign options for the defense of the United States of America and its global interests...to fly and fight in Air, Space and Cyberspace." (Wynne & Mosley, 2005) With the stand up of the AFCYBER command and the use of cyberspace to carry out our daily mission the U.S. needs to have a clear understanding of what war in cyberspace looks like and what the laws are governing war in cyberspace. This research and it's resulting data analysis is intended to provide a better understanding …

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Comparing Information Assurance Awareness Training For End-Users: A Content Analysis Examination Of Air Force And Defense Information Systems Agency User Training Modules, John W. Frugé Mar 2008

Comparing Information Assurance Awareness Training For End-Users: A Content Analysis Examination Of Air Force And Defense Information Systems Agency User Training Modules, John W. Frugé

Theses and Dissertations

Today, the threats to information security and assurance are great. While there are many avenues for IT professionals to safeguard against these threats, many times these defenses prove useless against typical system users. Mandated by laws and regulations, all government agencies and most private companies have established information assurance (IA) awareness programs, most of which include user training. Much has been given in the existing literature to laying out the guidance for the roles and responsibilities of IT professionals and higher level managers, but less is specified for "everyday" users of information systems. This thesis attempts to determine the content …

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An Evaluation And Implementation Guide For Current Groundwater Mass Flux Measurement Practices, Jack G. Wheeldon Iii Mar 2008

An Evaluation And Implementation Guide For Current Groundwater Mass Flux Measurement Practices, Jack G. Wheeldon Iii

Theses and Dissertations

Contaminant mass flux is an important parameter needed for decision making at sites with contaminated groundwater. New and potentially better methods for measuring mass flux are emerging. This study looks at the conventional transect method (TM), and the newer passive flux meter (PFM), modified integral pump test (MIPT), and tandem circulating well (TCW) methods. In order to facilitate transfer and application of these innovative technologies, it is essential that potential technology users have access to credible information that addresses technology capabilities, limitations, and costs. This study provides such information on each of the methods by reviewing implementation practices and comparing …

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Improving Mixed Variable Optimization Of Computational And Model Parameters Using Multiple Surrogate Functions, David Bethea Mar 2008

Improving Mixed Variable Optimization Of Computational And Model Parameters Using Multiple Surrogate Functions, David Bethea

Theses and Dissertations

This research focuses on reducing computational time in parameter optimization by using multiple surrogates and subprocess CPU times without compromising the quality of the results. This is motivated by applications that have objective functions with expensive computational times at high fidelity solutions. Applying, matching, and tuning optimization techniques at an algorithm level can reduce the time spent on unprofitable computations for parameter optimization. The objective is to recover known parameters of a flow property reference image by comparing to a template image that comes from a computational fluid dynamics simulation, followed by a numerical image registration and comparison process. Mixed …

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A Delphi Study Assessing Long-Term Access To Electronic Medical Records (Emr), Byron D. Nicholson Mar 2008

A Delphi Study Assessing Long-Term Access To Electronic Medical Records (Emr), Byron D. Nicholson

Theses and Dissertations

This research effort addressed the issue of long-term access to electronic medical records as technological generations become obsolete, thereby preventing the access to patient health information. Using the Delphi methodology, experts with experience in electronic medical records and applicable systems provided insight based on their years of hands-on experience managing and/or using records and these systems. The end result of this research was a collection of ideas that medical institutions and medical informaticians must consider to ensure that patients and hospitals do not lose long-term access to electronic medical records as electronic medical records and technology continually evolves. Results of …

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Suspicion Modeling In Support Of Cyber-Influence Operations/Tactics, Henry G. Paguirigan Mar 2008

Suspicion Modeling In Support Of Cyber-Influence Operations/Tactics, Henry G. Paguirigan

Theses and Dissertations

Understanding the cognitive process of IT user suspicion may assist organizations in development of network protection plans, personnel training, and tools necessary to identify and mitigate nefarious intrusions of IT systems. Exploration of a conceptual common ground between psycho-social and technology-related concepts of suspicion are the heart of this investigation. The complexities involved in merging these perspectives led to the overall research question: What is the nature of user suspicion toward IT: The research problem/phenomenon was addressed via extensive literature review, and use of the Interactive Qualitative Analysis problem/phenomenon. Analysis of the system led to the development of a model …

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Estimation Of The Number Of Microbial Species Comprising A Population, Melanie R. Slattery Mar 2008

Estimation Of The Number Of Microbial Species Comprising A Population, Melanie R. Slattery

Theses and Dissertations

The purpose of this research was to evaluate the appropriateness of using non-parametric estimators, specifically the Chao1, ACES, and Jackknife methods, for estimation of the number of unique species comprising a population. It goes on to develop a parametric method for the above stated problem. This research consisted of creating diverse populations, with known numbers of species, and applying the aforementioned non-parametric and parametric methods to samples drawn from the constructed populations. The parametric fitting of several different distributions to the sample data, including the lognormal, gamma, and Weibull was considered. Both types of methodologies were then applied to sample …

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Ionospheric Response To Solar Flares Using An Improved Version Of Sami2, Joseph P. Reich Iii Mar 2008

Ionospheric Response To Solar Flares Using An Improved Version Of Sami2, Joseph P. Reich Iii

Theses and Dissertations

Solar flares release energy, primarily at X-ray and EUV wavelengths, which is then absorbed mainly in Earth's ionosphere. This non-uniform absorption of energy alters the ionosphere's structure and can change the propagation of electromagnetic waves causing errors in GPS navigation, false radar echoes, and loss of High Frequency (HF) radio communications. Accurately modeling the ionospheric response to flares is the first step in predicting, and then mitigating, their effects. Accurately modeling these effects requires solar irradiance at a high cadence, to capture the flare, which may only last minutes, as well as treatment of the effects of photoelectrons. Sami2 is …

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Software Assurance Best Practices For Air Force Weapon And Information Technology Systems - Are We Bleeding?, Ryan A. Maxon Mar 2008

Software Assurance Best Practices For Air Force Weapon And Information Technology Systems - Are We Bleeding?, Ryan A. Maxon

Theses and Dissertations

In the corporate world, "bits mean money," and as the Department of Defense (DoD) becomes more and more reliant on net-centric warfare, bits mean national security. Software security threats are very real, as demonstrated by the constant barrage of Internet viruses, worms, Trojans, and hackers seeking to exploit the latest vulnerability. Most organizations focus their resources on reactive defenses such as firewalls, antivirus software, and encryption, however as demonstrated by the numerous attacks that are successful, those post facto measures are not enough to stop the bleeding. The DoD defines software assurance (SwA) as the "level of confidence that software …

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Demonstration Of A Strategy To Perform Two-Dimensional Diode Laser Tomography, Ryan N. Givens Mar 2008

Demonstration Of A Strategy To Perform Two-Dimensional Diode Laser Tomography, Ryan N. Givens

Theses and Dissertations

Demonstration of a strategy to perform two-dimensional diode laser tomography using a priori knowledge from symmetry arguments and computational fluid dynamic (CFD) calculations is presented for a flat flame burner. The strategy uses an optimization technique to determine flame diameter and location using a vector quantization approach. Next, the variance in a training set, produced from CFD calculations, is captured using principal components analysis. The information in the training set allows interpolation between beam paths resulting in temperature and density maps. Finally, the TDLAS temperature and density maps are shown to agree with traditional thermocouple measurements of the flat flame …

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An Image Based Bidirectional Reflectivity Distribution Function Experiment, Michael T. Hagg Mar 2008

An Image Based Bidirectional Reflectivity Distribution Function Experiment, Michael T. Hagg

Theses and Dissertations

The temperature dependence of Bidirectional Reflectivity Distribution Functions (BRDFs) is not well documented. For the sake of time and customer demand, current measurements are taken at room temperature, but the reflectivity of a material changes as a function of temperature. The assumption is that this change is uniform, and as such, the BRDF will retain its relative angular shape but perhaps be scaled in magnitude as a function of temperature. When BRDFs are to be used at elevated temperatures, a scaling factor is then applied. In addition, BRDF as a function of rate of change of temperature has been identified …

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Modeling Of Sbs Phase Conjugation In Multimode Step Index Fibers, Justin B. Spring Mar 2008

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 …

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An Examination Into How Group Performance Is Influenced By Various Communication Channels, Jason C. Norgaard Mar 2008

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 …

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Composable Distributed Access Control And Integrity Policies For Query-Based Wireless Sensor Networks, David W. Marsh Mar 2008

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 …

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Modulation Response Of Twin Optically Coupled Diode Lasers, Eric M. Golden Mar 2008

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 …

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A Formal Specification And Proof Of System Safety Using The Schematic Protection Model, Raymond S. Way Mar 2008

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. …

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An Analysis Of Groundwater Flow Patterns In A Constructed Treatment Wetland Cell, Rebecca S. Corbin Mar 2008

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 …

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A Hybrid Communications Network Simulation-Independent Toolkit, David M. Dines Mar 2008

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 …

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Developing A Reference Framework For Cybercraft Trust Evaluation, Shannon E. Hunt Mar 2008

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 …

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Multi-Objective Uav Mission Planning Using Evolutionary Computation, Adam J. Pohl Mar 2008

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 …

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Feasibility Study Of Encoding Operational Mission Metadata Into Ipv6 Packet Headers, Timothy R. Policarpio Mar 2008

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 …

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Establishing The Human Firewall: Reducing An Individual's Vulnerability To Social Engineering Attacks, Jamison W. Scheeres Mar 2008

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 …

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Behavior-Based Power Management In Autonomous Mobile Robots, Charles A. Fetzek Mar 2008

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 …

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Dynamic Behavior Sequencing In A Hybrid Robot Architecture, Jeffrey P. Duffy Mar 2008

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 …

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A Secure Group Communication Architecture For A Swarm Of Autonomous Unmanned Aerial Vehicles, Adrian N. Phillips Mar 2008

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 …

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Applying Automated Theorem Proving To Computer Security, Kelly K. Mcelroy Mar 2008

Applying Automated Theorem Proving To Computer Security, Kelly K. Mcelroy

Theses and Dissertations

While more and more data is stored and accessed electronically, better access control methods need to be implemented for computer security. Formal modelling and analysis have been successfully used in certain areas of computer systems, such as verifying the security properties of cryptographic and authentication protocols. However, formal models for computer systems in cyberspace, like networks, have hardly advanced. A highly regarded graduate textbook cites the Take-Grant model created in 1977 as one of the \current" examples of security modelling and analysis techniques. This model is rarely used in practice though. This research implements the Take-Grant Protection model's four de …

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Exploitation Of Self Organization In Uav Swarms For Optimization In Combat Environments, Dustin J. Nowak Mar 2008

Exploitation Of Self Organization In Uav Swarms For Optimization In Combat Environments, Dustin J. Nowak

Theses and Dissertations

This investigation focuses primarily on the development of effective target engagement for unmanned aerial vehicle (UAV) swarms using autonomous self-organized cooperative control. This development required the design of a new abstract UAV swarm control model which flows from an abstract Markov structure, a Partially Observable Markov Decision Process. Self-organization features, bio-inspired attack concepts, evolutionary computation (multi-objective genetic algorithms, differential evolution), and feedback from environmental awareness are instantiated within this model. The associated decomposition technique focuses on the iterative deconstruction of the problem domain state and dynamically building-up of self organizational rules as related to the problem domain environment. Resulting emergent …

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