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Air Force Institute of Technology

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Articles 1801 - 1830 of 3055

Full-Text Articles in Physical Sciences and Mathematics

Parallel Fast Multipole Method For Molecular Dynamics, Reid G. Ormseth Jun 2007

Parallel Fast Multipole Method For Molecular Dynamics, Reid G. Ormseth

Theses and Dissertations

We report on a parallel version of the Fast Multipole Method (FMM) implemented in the classical molecular dynamics code, NAMD (Not Another Molecular Dynamics program). This novel implementation of FMM aims to minimize interprocessor communication through the modification of the FMM grid to match the hybrid force and spatial decomposition scheme already present in NAMD. This new implementation has the benefit of replacing all-to-all communications broadcasts with direct communications between nearest neighbors. This results in a significant reduction in the amount of communication compared to earlier attempts to integrate FMM into common molecular dynamics programs. The early performance of FMM …

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An Infrared Camera Simulation For Estimating Spatial Temperature Profiles And Signal-To-Noise Ratios Of An Airborne Laser-Illuminated Target, David F. Orth Jun 2007

An Infrared Camera Simulation For Estimating Spatial Temperature Profiles And Signal-To-Noise Ratios Of An Airborne Laser-Illuminated Target, David F. Orth

Theses and Dissertations

Airborne Laser testing and evaluation can be aided by developing a spectrally-based infrared camera simulation to explore how the target surface's specular and diffuse reflectivities affect the observed signal-to-noise ratio (SNR) and how the target's temperature in the laser spot can estimated. This simulation provides for the observed irradiance, scaled by atmospheric absorption, to consist of the target's self-emission, reflected background emission, and the path emission from the observer to the target. The observed irradiance is scaled and distributed onto a focal plane array by way of a simulated optical system, whose effects are described by modulation transfer functions. The …

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Large Solutions Of Semilinear Elliptic Equations Under The Keller–Osserman Condition, Alan V. Lair Apr 2007

Large Solutions Of Semilinear Elliptic Equations Under The Keller–Osserman Condition, Alan V. Lair

Faculty Publications

Excerpt: We establish conditions on the function p that are necessary and sufficient for the existence of positive solutions, bounded and unbounded, of the given equation.

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Multi-Class Classification Averaging Fusion For Detecting Steganography, Benjamin M. Rodriguez, Gilbert L. Peterson, Sos S. Agaian Apr 2007

Multi-Class Classification Averaging Fusion For Detecting Steganography, Benjamin M. Rodriguez, Gilbert L. Peterson, Sos S. Agaian

Faculty Publications

Multiple classifier fusion has the capability of increasing classification accuracy over individual classifier systems. This paper focuses on the development of a multi-class classification fusion based on weighted averaging of posterior class probabilities. This fusion system is applied to the steganography fingerprint domain, in which the classifier identifies the statistical patterns in an image which distinguish one steganography algorithm from another. Specifically we focus on algorithms in which jpeg images provide the cover in order to communicate covertly. The embedding methods targeted are F5, JSteg, Model Based, OutGuess, and StegHide. The developed multi-class steganalvsis system consists of three levels: (1) …

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Steganalysis Feature Improvement Using Expectation Maximization, Benjamin M. Rodriguez, Gilbert L. Peterson, Sos S. Agaian Apr 2007

Steganalysis Feature Improvement Using Expectation Maximization, Benjamin M. Rodriguez, Gilbert L. Peterson, Sos S. Agaian

Faculty Publications

No abstract provided.

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Steganography Anomaly Detection Using Simple One Class Classification, Benjamin M. Rodriguez, Gilbert L. Peterson, Sos S. Agaian Apr 2007

Steganography Anomaly Detection Using Simple One Class Classification, Benjamin M. Rodriguez, Gilbert L. Peterson, Sos S. Agaian

Faculty Publications

No abstract provided.

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In Pursuit Of An Aptitude Test For Potential Cyberspace Warriors, Tiffiny S. Smith Mar 2007

In Pursuit Of An Aptitude Test For Potential Cyberspace Warriors, Tiffiny S. Smith

Theses and Dissertations

The Air Force has officially assumed the cyberspace mission. To perform this mission well, it is important to employ personnel who have the necessary skill sets and motivation to work in a cyberspace environment. The first step in employing the right people is to screen all possible candidates and select those with an aptitude for acquiring the skill sets and with the motivation to perform this work. This thesis attempts to determine the necessary skills and motivations to perform the cyberspace mission and recommends a screening process to select the candidates with the highest probability for success. Since this mission …

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Holes: Ionospheric Scintillation, Gps And Imputation, Robert A. Steenburgh Mar 2007

Holes: Ionospheric Scintillation, Gps And Imputation, Robert A. Steenburgh

Theses and Dissertations

Ionospheric scintillation of Global Positioning System (GPS) signals threatens navigation and military operations by degrading performance or making GPS unavailable. Scintillation is particularly active, although not limited to, a belt encircling the earth within ± 20 degrees of the geomagnetic equator. This belt also hosted roughly half of the completed U.S. military operations in the last decade. The authors examined scintillation data from Ascension Island, United Kingdom, and Ancon, Peru, in the Atlantic longitudinal sector as well as data from Parepare, Indonesia, and Marak Parak, Malaysia, in the Pacific longitudinal sector. From these data, they calculate percent probability of occurrence …

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A Multivariate Magnitude Robust Control Chart For Mean Shift Detection And Change Point Estimation, Ryan M. Harrell Mar 2007

A Multivariate Magnitude Robust Control Chart For Mean Shift Detection And Change Point Estimation, Ryan M. Harrell

Theses and Dissertations

Statistical control charts are often used to detect a change in an otherwise stable process. This process may contain several variables affecting process stability. The goal of any control chart is to detect an out-of-control state quickly and provide insight on when the process actually changed. This reduces the off-line time the quality engineer spends assigning causality. In this research, a multivariate magnitude robust chart (MMRC) was developed using a change point model and a likelihood-ratio approach. Here the process is considered in-control until one or more normally distributed process variables permanently and suddenly shifts to out-of-control, stable value. Using …

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Adaptive Gravitational Gossip In Monitoring The Joint Battlespace Infosphere, Edmund Descartes Aban Mar 2007

Adaptive Gravitational Gossip In Monitoring The Joint Battlespace Infosphere, Edmund Descartes Aban

Theses and Dissertations

Future USAF operations will be heavily dependent on having the "right information" at the "right time," and Joint Battlespace Infospheres (JBIs) are poised to fill that role. To do this, JBIs must be ubiquitous -- always accessible, secure and responsive. Of all the literature written regarding JBIs, the most important problem to solve in order to make JBIs work in mobile scenarios are scalability, reliability and adaptability to changing battlefield conditions. This paper explores the use of SBCast, a novel adaptive probabilistic protocol and a delivery mechanism for JBI updates and as a possible solution towards guaranteeing these qualities. It …

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Internet Protocol Geolocation: Development Of A Delay-Based Hybrid Methodology For Locating The Geographic Location Of A Network Node, John M. Roehl Mar 2007

Internet Protocol Geolocation: Development Of A Delay-Based Hybrid Methodology For Locating The Geographic Location Of A Network Node, John M. Roehl

Theses and Dissertations

Internet Protocol Geolocation (IP Geolocation), the process of determining the approximate geographic location of an IP addressable node, has proven useful in a wide variety of commercial applications. Commercial applications of IP Geolocation include market research, redirection for performance enhancement, restricting content, and combating fraud. The potential for military applications include securing remote access via geographic authentication, intelligence collection, and cyber attack attribution. IP Geolocation methods can be divided into three basic categories based upon what information is used to determine the geographic location of the given IP address: 1) Information contained in databases, 2) information that is leaked during …

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Wide Area Search And Engagement Simulation Validation, Michael J. Marlin Mar 2007

Wide Area Search And Engagement Simulation Validation, Michael J. Marlin

Theses and Dissertations

As unmanned aerial vehicles (UAVs) increase in capability, the ability to refuel them in the air is becoming more critical. Aerial refueling will extend the range, shorten the response times, and extend loiter time of UAVs. Executing aerial refueling autonomously will reduce the command and control, logistics, and training efforts associated with fielding UAV systems. Currently, the Air Force Research Lab is researching the various technologies required to conduct automated aerial refueling (AAR). One of the required technologies is the ability to autonomously rendezvous with the tanker. The goal of this research is to determine the control required to fly …

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Geospatial Informational Security Risks And Concerns Of The U.S. Air Force Geobase Program, Scott A. Bryant Mar 2007

Geospatial Informational Security Risks And Concerns Of The U.S. Air Force Geobase Program, Scott A. Bryant

Theses and Dissertations

Technological advancements such as Geospatial Information Systems (GIS) and the Internet have made it easier and affordable to share information, which enables complex and time sensitive decisions to be made with higher confidence. Further, advancements in information technology have dramatically increased the ability to store, manage, integrate, and correlate larger amounts of data to improve operational efficiency. However, the same technologies that enable increased productivity also provide increased capabilities to those wishing to do harm. Today’s military leaders are faced with the challenge of deciding how to make geospatial information collected on military installations and organizations available to authorized communities …

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Stimulated Brillouin Scattering Beam Cleanup And Beam Phasing Through Two Passive Channels, Omar Gamboa Mar 2007

Stimulated Brillouin Scattering Beam Cleanup And Beam Phasing Through Two Passive Channels, Omar Gamboa

Theses and Dissertations

Stimulated Brillouin scattering (SBS) beam cleanup and SBS piston correction properties are explored. This research measures the beam cleaning and phase-conjugating properties of stimulated Brillouin scattering in an optical fiber. The first stage of this research began by coupling an aberrated beam into a long multimode 62.5 micron core fiber to demonstrate its beam cleanup properties. The Stokes beam obtained was shown to be the fundamental fiber mode, LP01. The second stage spatially divided the pump beam into two equal halves. Each half was then sent through two different channels. The path length of one channel remained fixed while the …

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Anisotropy In The South Atlantic Anomaly, Shaun M. Easley Mar 2007

Anisotropy In The South Atlantic Anomaly, Shaun M. Easley

Theses and Dissertations

From June 2000 through July 2006, the TSX-5 satellite measured proton fluxes in the Earth’s magnetosphere using its CEASE instrument. A review of the satellite data by scientists at AFRL/VSBX revealed an unanticipated, recurring bi-modal structure in histograms of the proton counts. This research identified the bi-modal behavior as anisotropic in nature, and the result of two separate processes. At low altitudes the anisotropy was well described by the classic “East-West Effect.” Comparisons of the satellite data to simple analytical models are presented. At high altitudes, the anisotropy was the result of the detector measuring protons at different pitch angles …

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Spacecraft Proximity Operations Used To Estimate The Dynamical & Physical Properties Of A Resident Space Object, Abraham F. Brunner Mar 2007

Spacecraft Proximity Operations Used To Estimate The Dynamical & Physical Properties Of A Resident Space Object, Abraham F. Brunner

Theses and Dissertations

When conducting a space proximity operation, developing high-fidelity estimates of the dynamical and physical properties of a Resident Space Object (RSO) based on post-rendezvous observational data acquired, is imperative for the understanding of the RSO itself and the operating environment. This research investigates the estimation of relative motion dynamics, rotational dynamics, and the feasibility of estimating the moments of inertia of a RSO. Using the Hill-Clohessy-Wiltshire equations, rigid-body dynamics, and estimation theory, a nonlinear least squares estimation algorithm is implemented in the processing of range data from tracked observation points on the RSO body. Through simulation, it was determined that …

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Assessment Of The Impact Of Various Ionospheric Models On High Frequency Signal Raytracing, Joshua T. Werner Mar 2007

Assessment Of The Impact Of Various Ionospheric Models On High Frequency Signal Raytracing, Joshua T. Werner

Theses and Dissertations

An assessment of the impact of various ionospheric models on high-frequency (HF) signal raytracing is presented. Ionospheric refraction can strongly affect the propagation of HF signals. Consequently, Department of Defense missions such as over-the-horizon RADAR, HF communications, and geo-location all depend on an accurate specification of the ionosphere. Five case studies explore ionospheric conditions ranging from quiet conditions to solar flares and geomagnetic storms. It is shown that an E layer by itself can increase an HF signal’s ground range by over 100 km, stressing the importance of accurately specifying the lower ionosphere. It is also shown that the GPSII …

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Development Of A Screening Model For Design And Costing Of An Innovative Tailored Granular Activated Carbon Technology To Treat Perchlorate-Contaminated Water, William C. Powell Mar 2007

Development Of A Screening Model For Design And Costing Of An Innovative Tailored Granular Activated Carbon Technology To Treat Perchlorate-Contaminated Water, William C. Powell

Theses and Dissertations

Perchlorate contamination of drinking water is a problem that has recently gained national attention. The purpose of this research was to develop a tool to predict the cost and performance of tailored granular activated carbon (T-GAC), an innovative technology to treat perchlorate-contaminated water. The ability to predict cost and performance is essential to promote transfer and commercialization of innovative technologies. This study investigated how data obtained from small-scale laboratory tests could be applied to predict cost and performance of a full-scale T-GAC system to treat perchlorate-contaminated water. A technology model was developed using GAC design principles and using a multi-component …

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Use Of Tabu Search In A Solver To Map Complex Networks Onto Emulab Testbeds, Jason E. Macdonald Mar 2007

Use Of Tabu Search In A Solver To Map Complex Networks Onto Emulab Testbeds, Jason E. Macdonald

Theses and Dissertations

The University of Utah's solver for the testbed mapping problem uses a simulated annealing metaheuristic algorithm to map a researcher's experimental network topology onto available testbed resources. This research uses tabu search to find near-optimal physical topology solutions to user experiments consisting of scale-free complex networks. While simulated annealing arrives at solutions almost exclusively by chance, tabu search incorporates the use of memory and other techniques to guide the search towards good solutions. Both search algorithms are compared to determine whether tabu search can produce equal or higher quality solutions than simulated annealing in a shorter amount of time. It …

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Portable Diode Pumped Femtosecond Laser, David A. Jones Mar 2007

Portable Diode Pumped Femtosecond Laser, David A. Jones

Theses and Dissertations

This thesis discusses the work to make ultrashort pulsed lasers smaller and more economical. While sharing many of the basic properties of normal beam optics there are some specific properties in both creating and exploiting those pulses that must be understood. The discussion will focus on mode locking as the primary way of producing ultrashort pulses. Particular attention will be paid to intracavity group velocity dispersion and how to correct it inside the cavity. The discussion then turns to the basis of our work including initial cavity design and component selection with focus on the specific crystals used in the …

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A Study Of Bi-Directional Reflectance Distribution Functions And Their Effects On Infrared Signature Models, Samuel I. Harkiss Mar 2007

A Study Of Bi-Directional Reflectance Distribution Functions And Their Effects On Infrared Signature Models, Samuel I. Harkiss

Theses and Dissertations

Since 2004, AFIT has been developing a trend-analysis tool to assess large commercial aircraft infrared (LCAIR) signatures. In many cases, this code predicted signatures to within 10% of measured data. However, other results indicated that the single-bounce, specular-reflection algorithm being used failed to adequately simulate interactions between aircraft parts where either the specular component is dominated by diffuse reflection or part-to-part multiple-bounce reflections contribute significantly to the signature. This research incorporates Bi-Directional Reflectance Distribution Functions (BRDF's) and multiple-bounce calculations into the LCAIR model. A physical aircraft model was constructed from aluminum, and measurements were taken before and after a surface …

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Optical Tracking For Relative Positioning In Automated Aerial Refueling, James H. Spencer Mar 2007

Optical Tracking For Relative Positioning In Automated Aerial Refueling, James H. Spencer

Theses and Dissertations

An algorithm is designed to extract features from video of an air refueling tanker for use in determining the precise relative position of a receiver aircraft. The algorithm is based on receiving a known estimate of the tanker aircraft's position and attitude. The algorithm then uses a known feature model of the tanker to predict the location of those features on a video frame. A corner detector is used to extract features from the video. The measured corners are then associated with known features and tracked from frame to frame. For each frame, the associated features are used to calculate …

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The Effects Of Orthophosphate As A Copper Corrosion Control Inhibitor In High Alkalinity Drinking Water Systems, Stephen Grace Mar 2007

The Effects Of Orthophosphate As A Copper Corrosion Control Inhibitor In High Alkalinity Drinking Water Systems, Stephen Grace

Theses and Dissertations

The purpose of this research was to investigate orthophosphate as a corrosion inhibitor for copper pipe in a high-alkalinity drinking water system. Specifically, this thesis sought to answer three research questions regarding the impact of orthophosphate treatment, the nature of the mechanism by which orthophosphate controls copper corrosion, and the value of equilibrium modeling in predicting orthophosphate’s effects. The research questions were answered through a comprehensive literature review and experimental methodology integrating laboratory jar tests, water sampling and analysis from a field investigation, qualitative solids analysis, and equilibrium model application. This study analyzed field data obtained over the course of …

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Refinement Of An Instrument To Assess Readiness For Knowledge Management, Landon C. Bailey Mar 2007

Refinement Of An Instrument To Assess Readiness For Knowledge Management, Landon C. Bailey

Theses and Dissertations

Academics and practitioners have described knowledge as a primary source for competitive advantage for organizations; however, many attempts at instituting knowledge management programs to increase organizational competitiveness do not succeed. Instituting knowledge management programs generally requires organizations to make significant changes and the concept of readiness has long been believed to be an important precondition for successful organizational change. By linking previous research in enablers for knowledge management and organizational change, it is possible to adapt an established organizational change readiness instrument to measure readiness for knowledge management. This study culminates in the development and field-testing of the resultant knowledge …

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Using Concept Maps To More Efficiently Create Intelligence Information Models, Christopher E. Coryell Mar 2007

Using Concept Maps To More Efficiently Create Intelligence Information Models, Christopher E. Coryell

Theses and Dissertations

Information models are a critical tool that enables intelligence customers to quickly and accurately comprehend U.S. intelligence agency products. The Knowledge Pre-positioning System (KPS) is the standard repository for information models at the National Air and Space Intelligence Center (NASIC). The current approach used by NASIC to build a KPS information model is laborious and costly. Intelligence analysts design an information model using a manual, butcher-paper-based process. The output of their work is then entered into KPS by either a single NASIC KPS "database modeler" or a contractor (at a cost of roughly $100K to the organization). This thesis proposes …

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Hardware Virtualization Applied To Rootkit Defense, Douglas P. Medley Mar 2007

Hardware Virtualization Applied To Rootkit Defense, Douglas P. Medley

Theses and Dissertations

This research effort examines the idea of applying virtualization hardware to enhance operating system security against rootkits. Rootkits are sets of tools used to hide code and/or functionality from the user and operating system. Rootkits can accomplish this feat through using access to one part of an operating system to change another part that resides at the same privilege level. Hardware assisted virtualization (HAV) provides an opportunity to defeat this tactic through the introduction of a new operating mode. Created to aid operating system virtualization, HAV provides hardware support for managing and saving multiple states of the processor. This hardware …

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Use Of Thrust Vectors In Support Of The Cybercraft Initiative, Michael Stevens Mar 2007

Use Of Thrust Vectors In Support Of The Cybercraft Initiative, Michael Stevens

Theses and Dissertations

The CyberCraft Initiative is designing a framework for command and control of future Air Force Cyber-weapon systems, that autonomously operate and defend the Air Force networks and information systems to provide Cyberspace Superiority in support of the defense of the United States. The fundamental research question of the CyberCraft Initiative is "What is required for a commander to trust a CyberCraft to autonomously defend military information systems?" The Trust Vector model is one method of integrating trust into the CyberCraft fleet. Trust Vectors define trust and distrust between agents based on three components; current and historical data, intrinsic knowledge of …

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Beyond Passswords: Usage And Policy Transformation, Alan S. Alsop Mar 2007

Beyond Passswords: Usage And Policy Transformation, Alan S. Alsop

Theses and Dissertations

The purpose of this research is to determine whether the transition to a two-factor authentication system is more secure than a system that relied only on what users “know” for authentication. While we found that factors that made passwords inherently vulnerable did not transfer to the PIN portion of a two-factor authentication system, we did find significant problems relating to usability, worker productivity, and the loss and theft of smart cards. The new authentication method has disrupted our ability to stay connected to ongoing mission issues, forced some installations to cut off remote access for their users and in one …

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Professionalism In The Air Force: A Comparative Analysis Of Commissioned Officers With Non-Commissioned Officers, Edward K. Boyd Mar 2007

Professionalism In The Air Force: A Comparative Analysis Of Commissioned Officers With Non-Commissioned Officers, Edward K. Boyd

Theses and Dissertations

Decades ago, military sociologists predicted a rising trend among officers away from traditional institutional military values and toward more economically-based occupational values due to the effects of the transition from a conscription-based military to an all-volunteer force. Subsequent empirical research resulted in data that supports such predictions. More recent researchers have suggested that in addition to the all-volunteer force, an increase on technology may also accelerate the trend toward occupationalism and away from traditional institutional military values and the warrior ethos that typically define successful military organizations. The officer corps may be particularly vulnerable to occupationalism due to increased technical …

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Implementation And Optimization Of The Advanced Encryption Standard Algorithm On An 8-Bit Field Programmable Gate Array Hardware Platform, Ryan J. Silva Mar 2007

Implementation And Optimization Of The Advanced Encryption Standard Algorithm On An 8-Bit Field Programmable Gate Array Hardware Platform, Ryan J. Silva

Theses and Dissertations

The contribution of this research is three-fold. The first is a method of converting the area occupied by a circuit implemented on a Field Programmable Gate Array (FPGA) to an equivalent as a measure of total gate count. This allows direct comparison between two FPGA implementations independent of the manufacturer or chip family. The second contribution improves the performance of the Advanced Encryption Standard (AES) on an 8-bit computing platform. This research develops an AES design that occupies less than three quarters of the area reported by the smallest design in current literature as well as significantly increases area efficiency. …

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