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Air Force Institute of Technology

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Articles 1681 - 1710 of 2678

Full-Text Articles in Physical Sciences and Mathematics

Modeling Information Quality Expectation In Unmanned Aerial Vehicle Swarm Sensor Databases, Patrick D. Baldwin Mar 2005

Modeling Information Quality Expectation In Unmanned Aerial Vehicle Swarm Sensor Databases, Patrick D. Baldwin

Theses and Dissertations

Swarming Unmanned Aerial Vehicles (UAVs) are the future of Intelligence, Surveillance and Reconnaissance (ISR). Swarms of hundreds of these vehicles, each equipped with multiple sensors, will one day fill the skies over hostile areas. As the sensors collect hundreds of gigabytes of data, telemetry data links will be unable to transmit the complete data picture to the ground in real time. The collected data will be stored on board the UAVs and selectively downloaded through queries issued from analysts on the ground. Analysts expect to find relevant sensor data within the collection of acquired sensor data. This expectation is not …

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Evaluation Of The Ad Hoc On-Demand Distance Vector Routing Protocol For Mobile Ad Hoc Networks, Amber J. Rickmon Mar 2005

Evaluation Of The Ad Hoc On-Demand Distance Vector Routing Protocol For Mobile Ad Hoc Networks, Amber J. Rickmon

Theses and Dissertations

Routing protocols designed for wired networks cannot be used in mobile ad hoc networks (MANETs) due to the dynamic topology, limited throughput, and energy constraints. New routing protocols have been designed for use in MANETs, but have not been thoroughly tested under realistic conditions such as node movement, number of sources, the presence of obstacles, and node speed. This research evaluates the performance of ad hoc on-demand distance vector routing with respect to throughput, goodput ratio, end-to-end (ETE) delay, node pair packet delivery rate, and node pair end-to-end delay. It shows these performance metrics vary significantly according to the choice …

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Determination Of Structure From Motion Using Aerial Imagery, Paul R. Graham Mar 2005

Determination Of Structure From Motion Using Aerial Imagery, Paul R. Graham

Theses and Dissertations

The structure from motion process creates three-dimensional models from a sequence of images. Until recently, most research in this field has been restricted to land-based imagery. This research examines the current methods of land-based structure from motion and evaluates their performance for aerial imagery. Current structure from motion algorithms search the initial image for features to track though the subsequent images. These features are used to create point correspondences between the two images. The correspondences are used to estimate the motion of the camera and then the three-dimensional structure of the scene. This research tests current algorithms using synthetic data …

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The Use Of X-Ray Pulsars For Aiding Gps Satellite Orbit Determination, Dennis W. Woodfork Ii Mar 2005

The Use Of X-Ray Pulsars For Aiding Gps Satellite Orbit Determination, Dennis W. Woodfork Ii

Theses and Dissertations

This research proposes the use of an existing "signal of opportunity" - namely x-ray pulsars - to improve the accuracy and robustness of the GPS satellite and clock estimation algorithm. Improvement in satellite and clock accuracy results in a direct benefit to the user. A simulation has been developed to determine the effects of using x-ray pulsar measurements on the GPS Operational Control Segment. The epoch-specific position, velocity, and clock errors of all GPS satellites in the constellation were estimated using both pseudoranges and time-difference-of-arrival (TDOA) measurements from pulsars. The primary measure of accuracy is a constellation Signal-In-Space Range Error …

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Computational Model Of One-Dimensional Dielectric Barrier Discharges, Krista G. Marchand Mar 2005

Computational Model Of One-Dimensional Dielectric Barrier Discharges, Krista G. Marchand

Theses and Dissertations

As theory lags experiment for dielectric barrier discharge flow control, two different computational methods are implemented to give further insight into characteristics of the dielectric barrier discharge (DBD). A one-dimensional fluid model of a surface-type dielectric barrier discharge is created using He as the background gas. This simple model, which only considers ionizing collisions and recombination in the electropositive gas, creates an important framework for future studies into the origin of experimentally observed flow-control effects of the DBD. The two methods employed in this study include the semi-implicit sequential algorithm and the fully implicit simultaneous algorithm. The first involves consecutive …

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National Security Agency (Nsa) Systems And Network Attack Center (Snac) Security Guides Versus Known Worms, Matthew W. Sullivan Mar 2005

National Security Agency (Nsa) Systems And Network Attack Center (Snac) Security Guides Versus Known Worms, Matthew W. Sullivan

Theses and Dissertations

Internet worms impact Internet security around the world even though there are many defenses to prevent the damage they inflict. The National Security Agency (NSA) Systems and Network Attack Center (SNAC) publishes in-depth configuration guides to protect networks from intrusion; however, the effectiveness of these guides in preventing the spread of worms hasn't been studied. This thesis establishes how well the NSA SNAC guides protect against various worms and exploits compared to Microsoft patches alone. It also identifies the aspects of the configuration guidance that is most effective in the absence of patches and updates, against network worm and e-mail …

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Modeling Groundwater Flow And Contaminant Transporting Fractured Aquifers, Jason M. Bordas Mar 2005

Modeling Groundwater Flow And Contaminant Transporting Fractured Aquifers, Jason M. Bordas

Theses and Dissertations

The hybrid discrete fracture network/equivalent porous medium (DFN/EPM) model was selected for analysis and application to simulate a contaminated site in this study. The DFN/EPM was selected because it appeared to have the potential to aid decision making by remedial project managers at contaminated DoD fractured aquifer sites. This model can use data that are typically available at a site while incorporating the important processes relevant to describing contaminant transport in a fractured medium. The model was applied to simulate the operation of a pump-and-treat remedial action at a trichloroethene-contaminated fractured aquifer at Pease AFB. The model was able to …

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Assessing The Usefulness Of Visualization Tools To Investigate Hidden Patterns With Insider Attack Cases, Amy M. Rammel Mar 2005

Assessing The Usefulness Of Visualization Tools To Investigate Hidden Patterns With Insider Attack Cases, Amy M. Rammel

Theses and Dissertations

The insider threat is a major concern for organizations. Open markets, technological advances, and the evolving definition of employee have exacerbated the insider threat. Insider threat research efforts are focusing on both prevention and detection techniques. However, recent security violation trends highlight the damage insider attacks cause organizations and illuminate why organizations and researchers must develop new approaches to this challenge. Although fruitful research is being conducted and new technologies are being applied to the insider threat problem, companies remain susceptible to the costly damage generated by insider threat actions. This research explored how visualization tools may be useful in …

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Daytime Detection Of Space Objects, Alistair D. Funge Mar 2005

Daytime Detection Of Space Objects, Alistair D. Funge

Theses and Dissertations

Space Situational Awareness (SSA) requires repeated object updates for orbit accuracy. Detection of unknown objects is critical. A daytime model was developed that evaluated sun flares and assessed thermal emissions from space objects. Iridium satellites generate predictable sun glints. These were used as a model baseline for daytime detections. Flares and space object thermal emissions were examined for daytime detection. A variety of geometric, material and atmospheric characteristics affected this daytime detection capability. In a photon noise limited mode, simulated Iridium flares were detected. The peak Signal-to- Noise Ratios (SNR) were 6.05e18, 9.63e5, and 1.65e7 for the nighttime, daytime and …

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Real-Time Mapping Using Stereoscopic Vision Optimization, Kevin M. Biggs Mar 2005

Real-Time Mapping Using Stereoscopic Vision Optimization, Kevin M. Biggs

Theses and Dissertations

This research focuses on efficient methods of generating 2D maps from stereo vision in real-time. Instead of attempting to locate edges between objects, we make the assumption that the representative surfaces of objects in a view provide enough information to generate a map while taking less time to locate during processing. Since all real-time vision processing endeavors are extremely computationally intensive, numerous optimization techniques are applied to allow for a real-time application: horizontal spike smoothing for post-disparity noise, masks to focus on close-proximity objects, melding for object synthesis, and rectangular fitting for object extraction under a planar assumption. Additionally, traditional …

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Robot Mapping With Real-Time Incremental Localization Using Expectation Maximization, Kevin L. Owens Mar 2005

Robot Mapping With Real-Time Incremental Localization Using Expectation Maximization, Kevin L. Owens

Theses and Dissertations

This research effort explores and develops a real-time sonar-based robot mapping and localization algorithm that provides pose correction within the context of a single room, to be combined with pre-existing global localization techniques, and thus produce a single, well-formed map of an unknown environment. Our algorithm implements an expectation maximization algorithm that is based on the notion of the alpha-beta functions of a Hidden Markov Model. It performs a forward alpha calculation as an integral component of the occupancy grid mapping procedure using local maps in place of a single global map, and a backward beta calculation that considers the …

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A Three Dimensional Helmet Mounted Primary Flight Reference For Paratroopers, Jason I. Thompson Mar 2005

A Three Dimensional Helmet Mounted Primary Flight Reference For Paratroopers, Jason I. Thompson

Theses and Dissertations

This thesis seeks to develop a Heads Up Display (HUD) presented on a Helmet Mounted Display (HMD), which presents a three-dimensional, graphical, predictive navigational reference to a paratrooper during a High Altitude, High Opening (HAHO) parachute jump. A Path Generating Algorithm (PGA) takes as input the Landing Zone's (LZ) location, the wind profile, and the paratrooper's parachute's performance characteristics, and returns a set of waypoints for the paratrooper to follow. The PGA attempts to maximize the distance that the paratrooper travels. The PGA's output is used to build a path to the LZ from a Release Point (RP). During the …

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Efficient Generation Of Social Network Data From Computer-Mediated Communication Logs, Jason Wei Sung Yee Mar 2005

Efficient Generation Of Social Network Data From Computer-Mediated Communication Logs, Jason Wei Sung Yee

Theses and Dissertations

The insider threat poses a significant risk to any network or information system. A general definition of the insider threat is an authorized user performing unauthorized actions, a broad definition with no specifications on severity or action. While limited research has been able to classify and detect insider threats, it is generally understood that insider attacks are planned, and that there is a time period in which the organization's leadership can intervene and prevent the attack. Previous studies have shown that the person's behavior will generally change, and it is possible that social network analysis could be used to observe …

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Analysis Of Effects Of Bgp Black Hole Routing On A Network Like The Niprnet, Michael D. Kleffman Mar 2005

Analysis Of Effects Of Bgp Black Hole Routing On A Network Like The Niprnet, Michael D. Kleffman

Theses and Dissertations

The Department of Defense (DoD) relies heavily on the Non-secure Internet Protocol Router Network (NIPRNET) to exchange information freely between departments, services, bases, posts, and ships. The NIPRNET is vulnerable to various attacks, to include physical and cyber attacks. One of the most frequently used cyber attacks by criminally motivated hackers is a Distributed Denial of Service (DDoS) attack. DDoS attacks can be used to exhaust network bandwidth and router processing capabilities, and as a leveraging tool for extortion. Border Gateway Protocol (BGP) black hole routing is a responsive defensive network technique for mitigating DDoS attacks. BGP black hole routing …

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Deep Level Defects In Electron-Irradiated Aluminum Gallium Nitride Grown By Molecular Beam Epitaxy, Michael R. Hogsed Mar 2005

Deep Level Defects In Electron-Irradiated Aluminum Gallium Nitride Grown By Molecular Beam Epitaxy, Michael R. Hogsed

Theses and Dissertations

Aluminum gallium nitride (AlGaN)-based devices are attractive candidates for integration into future Air Force communication and sensor platforms, including those that must operate in harsh radiation environments. In this study, the electrical and optical properties of 1.0 MeV electron irradiated n-AlxGa1-xN are characterized for aluminum mole fraction x = 0.0 to 0.3 using deep level transient spectroscopy (DLTS), temperature-dependent Hall, and cathodoluminescence (CL) measurements. Following irradiation of the AlGaN, it is found that four different electron traps are created, having energy levels within 0.4 eV below the conduction band edge. Three of these traps correspond to …

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Validation Of An Innovative Groundwater Contaminant Flux Measurement Method, Seh J. Kim Mar 2005

Validation Of An Innovative Groundwater Contaminant Flux Measurement Method, Seh J. Kim

Theses and Dissertations

The ability to measure groundwater contaminant flux is increasingly being recognized as crucial in order to prioritize contaminated site cleanups, estimate the efficiency of remediation technologies, measure rates of natural attenuation, and apply proper source terms to model groundwater contaminant transport. An innovative mass flux measurement method using horizontal flow treatment wells (HFTWs) was developed recently to compensate for the disadvantages of other flux measurement methods that are being used. Flux measurement methods can be categorized as either point methods or integral methods. As the name suggests, point methods measure flux at a specific point or points in the subsurface. …

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Passwords: A Survey On Usage And Policy, Kurt W. Martinson Mar 2005

Passwords: A Survey On Usage And Policy, Kurt W. Martinson

Theses and Dissertations

Computer password use is on the rise. Passwords have become one of the primary authentication methods used today. It is because of their high use that organizations have started to place parameters on passwords. Are password restrictions a nuisance? What are some of the consequences that result as organizations place the burden of their computer security on passwords? This thesis analyzes the results of a survey instrument that was used to determine if individuals are using similar techniques or patterns when choosing or remembering their passwords. It also looks at how individuals feel about using passwords. In addition, the authors …

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A Genetic Algorithm For Uav Routing Integrated With A Parallel Swarm Simulation, Matthew A. Russell Mar 2005

A Genetic Algorithm For Uav Routing Integrated With A Parallel Swarm Simulation, Matthew A. Russell

Theses and Dissertations

This research investigation addresses the problem of routing and simulating swarms of UAVs. Sorties are modeled as instantiations of the NP-Complete Vehicle Routing Problem, and this work uses genetic algorithms (GAs) to provide a fast and robust algorithm for a priori and dynamic routing applications. Swarms of UAVs are modeled based on extensions of Reynolds' swarm research and are simulated on a Beowulf cluster as a parallel computing application using the Synchronous Environment for Emulation and Discrete Event Simulation (SPEEDES). In a test suite, standard measures such as benchmark problems, best published results, and parallel metrics are used as performance …

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Accelerating Missile Threat Engagement Simulations Using Personal Computer Graphics Cards, Sean E. Jeffers Mar 2005

Accelerating Missile Threat Engagement Simulations Using Personal Computer Graphics Cards, Sean E. Jeffers

Theses and Dissertations

The 453rd Electronic Warfare Squadron supports on-going military operations by providing battlefield commanders with aircraft ingress and egress routes that minimize the risk of shoulder or ground-fired missile attacks on our aircraft. To determine these routes, the 453rd simulates engagements between ground-to-air missiles and allied aircraft to determine the probability of a successful attack. The simulations are computationally expensive, often requiring two-hours for a single 10-second missile engagement. Hundreds of simulations are needed to perform a complete risk assessment which includes evaluating the effectiveness of countermeasures such as flares, chaff, jammers, and missile warning systems. Thus, the need for faster …

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An Analysis Of Perturbed Quantization Steganography In The Spatial Domain, Matthew D. Spisak Mar 2005

An Analysis Of Perturbed Quantization Steganography In The Spatial Domain, Matthew D. Spisak

Theses and Dissertations

Steganography is a form of secret communication in which a message is hidden into a harmless cover object, concealing the actual existence of the message. Due to the potential abuse by criminals and terrorists, much research has also gone into the field of steganalysis - the art of detecting and deciphering a hidden message. As many novel steganographic hiding algorithms become publicly known, researchers exploit these methods by finding statistical irregularities between clean digital images and images containing hidden data. This creates an on-going race between the two fields and requires constant countermeasures on the part of steganographers in order …

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Detection Of Bacillus Spores By Aptamer Selectivity Using Atomic Force Microscopy, Nina M. Houtkooper Mar 2005

Detection Of Bacillus Spores By Aptamer Selectivity Using Atomic Force Microscopy, Nina M. Houtkooper

Theses and Dissertations

The anthrax attack of Oct 2001 demonstrates the need for a rapid detector for spores of Bacillus anthracis (BA). Current technology requires cultures of BA to be grown for 24 hours. Using aptamers, a type of nucleic acid ligand selective for a target molecule, to select BA spores for measurement without culturing is a possible solution for quicker detection. An aptamer having a specially selected structure is expected to selectively bind to the surface of its target spore, separating it from other material. An atomic force microscopy (AFM) method was developed to test this selectivity. Aptamers having structure selected to …

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An Evolutionary Algorithm To Generate Ellipsoid Detectors For Negative Selection, Joseph M. Shapiro Mar 2005

An Evolutionary Algorithm To Generate Ellipsoid Detectors For Negative Selection, Joseph M. Shapiro

Theses and Dissertations

Negative selection is a process from the biological immune system that can be applied to two-class (self and nonself) classification problems. Negative selection uses only one class (self) for training, which results in detectors for the other class (nonself). This paradigm is especially useful for problems in which only one class is available for training, such as network intrusion detection. Previous work has investigated hyper-rectangles and hyper-spheres as geometric detectors. This work proposes ellipsoids as geometric detectors. First, the author establishes a mathematical model for ellipsoids. He develops an algorithm to generate ellipsoids by training on only one class of …

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A New Blind Method For Detecting Novel Steganography, Brent T. Mcbride, Gilbert L. Peterson, Steven C. Gustafson Feb 2005

A New Blind Method For Detecting Novel Steganography, Brent T. Mcbride, Gilbert L. Peterson, Steven C. Gustafson

Faculty Publications

Steganography is the art of hiding a message in plain sight. Modern steganographic tools that conceal data in innocuous-looking digital image files are widely available. The use of such tools by terrorists, hostile states, criminal organizations, etc., to camouflage the planning and coordination of their illicit activities poses a serious challenge. Most steganography detection tools rely on signatures that describe particular steganography programs. Signature-based classifiers offer strong detection capabilities against known threats, but they suffer from an inability to detect previously unseen forms of steganography. Novel steganography detection requires an anomaly-based classifier. This paper describes and demonstrates a blind classification …

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The Kinetics Following Photolysis Of Nitrosyl Bromide, Lori A. Mahoney Dec 2004

The Kinetics Following Photolysis Of Nitrosyl Bromide, Lori A. Mahoney

Theses and Dissertations

One candidate for the development of a tunable laser in the mid-infrared for use as a defensive countermeasure against passive sensors exploits the nitric oxide (NO) transition at 5.4 μm. However, the difficulty with this mechanism is that when bromine (Br2) and NO are present in a mixture, nitrosyl bromide (BrNO) is also created. The absorption bands present in BrNO complicate the design of such a laser. This thesis determines the forward and reverse rate constants of the reaction of Br2 and NO to form BrNO following the photolysis of BrNO using Fourier Transform Infrared absorption spectroscopy. …

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Design And Model Verification Of An Infrared Chromotomographic Imaging System, Daniel A. Lemaster Dec 2004

Design And Model Verification Of An Infrared Chromotomographic Imaging System, Daniel A. Lemaster

Theses and Dissertations

A prism chromotomographic hyperspectral imaging sensor is being developed to aid in the study of bomb phenomenology. Reliable chromotomographic reconstruction depends on accurate knowledge of the sensor specific point spread function over all wavelengths of interest. The purpose of this research is to generate the required point spread functions using wave optics techniques and a phase screen model of system aberrations. Phase screens are generated using the Richardson-Lucy algorithm for extracting point spread functions and Gerchberg-Saxton algorithm for phase retrieval. These phase screens are verified by comparing the modeled results of a blackbody source with measurements made using a chromotomographic …

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Consistency Results For The Roc Curves Of Fused Classifiers, Kristopher S. Bjerkaas Dec 2004

Consistency Results For The Roc Curves Of Fused Classifiers, Kristopher S. Bjerkaas

Theses and Dissertations

The U.S. Air Force is researching the fusion of multiple classifiers. Given a finite collection of classifiers to be fused, one seeks a new classifier with improved performance. An established performance quantifier is the Receiver Operating Characteristic (ROC) curve, which allows one to view the probability of detection versus the probability of false alarm in one graph. Previous research shows that one does not have to perform tests to determine the ROC curve of this new fused classifier. If the ROC curve for each individual classifier has been determined, then formulas for the ROC curve of the fused classifier exist …

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Forensic Analysis Of Digital Image Tampering, Jonathan R. Sturak Dec 2004

Forensic Analysis Of Digital Image Tampering, Jonathan R. Sturak

Theses and Dissertations

The use of digital photography has increased over the past few years, a trend which opens the door for new and creative ways to forge images. The manipulation of images through forgery influences the perception an observer has of the depicted scene, potentially resulting in ill consequences if created with malicious intentions. This poses a need to verify the authenticity of images originating from unknown sources in absence of any prior digital watermarking or authentication technique. This research explores the holes left by existing research; specifically, the ability to detect image forgeries created using multiple image sources and specialized methods …

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Pattern Search Ranking And Selection Algorithms For Mixed-Variable Optimization Of Stochastic Systems, Todd A. Sriver Sep 2004

Pattern Search Ranking And Selection Algorithms For Mixed-Variable Optimization Of Stochastic Systems, Todd A. Sriver

Theses and Dissertations

A new class of algorithms is introduced and analyzed for bound and linearly constrained optimization problems with stochastic objective functions and a mixture of design variable types. The generalized pattern search (GPS) class of algorithms is extended to a new problem setting in which objective function evaluations require sampling from a model of a stochastic system. The approach combines GPS with ranking and selection (R&S) statistical procedures to select new iterates. The derivative-free algorithms require only black-box simulation responses and are applicable over domains with mixed variables (continuous, discrete numeric, and discrete categorical) to include bound and linear constraints on …

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Visual Unified Modeling Language For The Composition Of Scenarios In Modeling And Simulation Systems, Daniel E. Swayne Sep 2004

Visual Unified Modeling Language For The Composition Of Scenarios In Modeling And Simulation Systems, Daniel E. Swayne

Theses and Dissertations

The Department of Defense uses modeling and simulation systems in many various roles, from research and training to modeling likely outcomes of command decisions. Simulation systems have been increasing in complexity with the increased capability of low-cost computer systems to support these DOD requirements. The demand for scenarios is also increasing, but the complexity of the simulation systems has caused a bottleneck in scenario development due to the limited number of individuals with knowledge of the arcane simulator languages in which these scenarios are written. This research combines the results of previous AFIT efforts in visual modeling languages to create …

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Quantifying Initial Condition And Parametric Uncertainties In A Nonlinear Aeroelastic System With An Efficient Stochastic Algorithm, Daniel R. Millman Sep 2004

Quantifying Initial Condition And Parametric Uncertainties In A Nonlinear Aeroelastic System With An Efficient Stochastic Algorithm, Daniel R. Millman

Theses and Dissertations

There is a growing interest in understanding how uncertainties in flight conditions and structural parameters affect the character of a limit cycle oscillation (LCO) response, leading to failure of an aeroelastic system. Uncertainty quantification of a stochastic system (parametric uncertainty) with stochastic inputs (initial condition uncertainty) has traditionally been analyzed with Monte Carlo simulations (MCS). Probability density functions (PDF) of the LCO response are obtained from the MCS to estimate the probability of failure. A candidate approach to efficiently estimate the PDF of an LCO response is the stochastic projection method. The objective of this research is to extend the …

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