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Articles 721 - 750 of 2678
Full-Text Articles in Physical Sciences and Mathematics
Text Classification Of Installation Support Contract Topic Models For Category Management, William C. Sevier
Text Classification Of Installation Support Contract Topic Models For Category Management, William C. Sevier
Theses and Dissertations
Air Force Installation Contracting Agency manages nearly 18 percent of total Air Force spend, equating to approximately 57 billion dollars. To improve strategic sourcing, the organization is beginning to categorize installation-support spend and assign accountable portfolio managers to respective spend categories. A critical task in this new strategic environment includes the appropriate categorization of Air Force contracts into newly created, manageable spend categories. It has been recognized that current composite categories have the opportunity to be further distinguished into sub-categories leveraging text analytics on the contract descriptions. Furthermore, upon establishing newly constructed categories, future contracts must be classified into these …
A Method To Determine The Viability Of Photovoltaic Systems In Various Climate Regions, Joseph A. Applebee
A Method To Determine The Viability Of Photovoltaic Systems In Various Climate Regions, Joseph A. Applebee
Theses and Dissertations
The purpose of this study is to manufacture and disseminate 37 photovoltaic test systems which will be located at various United States Air Force installations worldwide. The Air Force's goals in renewable energy are to determine the potential for systems to aid in promoting resiliency for an installation's energy demands. The test systems are designed to collect climate and power production data from each test site and associated photovoltaic cells. The overall goal of the test system data collection is to determine the correlation between power output of photovoltaic panels and the associated geographic region climate classification. This study does …
Analysis Of Temperature And Humidity Effects On Horizontal Photovoltaic Panels, Corey J. Booker
Analysis Of Temperature And Humidity Effects On Horizontal Photovoltaic Panels, Corey J. Booker
Theses and Dissertations
The United States Air Force seeks to address power grid vulnerability and bolster energy resilience through the use of renewable energy sources. Air Force Institute of Technology engineers designed and manufactured control systems to monitor power production from the most widely-used silicon-based solar cells at 38 testing locations around the globe spanning the majority of climate types. Researchers conducted multivariate regression analysis to establish a statistical relationship between photovoltaic power output, ambient temperature, and humidity pertaining to monocrystalline and polycrystalline photovoltaic panels. Formulated models first characterized power output globally, then by specific climate type with general inaccuracy. Location-specific models are …
Quantifying Permafrost Extent, Condition, And Degradation Rates At Department Of Defense Installations In The Arctic, Christopher A.J. Edlund
Quantifying Permafrost Extent, Condition, And Degradation Rates At Department Of Defense Installations In The Arctic, Christopher A.J. Edlund
Theses and Dissertations
The DoD is planning over $500M in military construction on Eielson Air Force Base (AFB) within the next three years. This construction program will expand the footprint of facilities and change parts of the storm water management scheme, which may have second order effects on the underlying permafrost layer. These changes in permafrost will drive engineering decision making at local and regional levels, and help shape the overall strategy for military readiness in the Arctic. Little site-specific knowledge exists on the human caused effects to permafrost at this location. In 2016, the permafrost degradation rates at Eielson AFB were modeled …
Simulation And Modeling Of High Energy Laser-Induced Droplet Shattering In Clouds, Andrew P. Lawrence
Simulation And Modeling Of High Energy Laser-Induced Droplet Shattering In Clouds, Andrew P. Lawrence
Theses and Dissertations
The process of a megawatt laser passing through a cloud is modeled. Specifically, the potential for droplet shattering is explored as a method for clearing a path through a cloud through which a second laser may be sent unobstructed. The paraxial approximation, an approximation to Maxwell's equations, is used to model the beam propagation. The simplified cloud model has assumed a distribution of pure, timescale restricted, droplets evenly distributed with uniform radius and initial temperature. All of the radiative heating is assumed to heat the droplet, neglecting radius change and vaporization based upon characteristic time scales. A 1+1 dimensional model …
A New Analysis Of The Gálvez-Davison Index For Convective Forecasts In Northern Africa, Gabriel D. Donndelinger
A New Analysis Of The Gálvez-Davison Index For Convective Forecasts In Northern Africa, Gabriel D. Donndelinger
Theses and Dissertations
Severe wind gusts and thunderstorms have been difficult to forecast in Africa. Traditional convective forecast tools (e.g. Total Totals Index, Lifted Index, K Index (KI) and Convective Available Potential Energy) do not accurately portray potential for thunderstorms in Africa. This research effort used the Gálvez-Davison Index (GDI), a convective index created for the tropics, and assess its applicability to northern Africa. GDI was produced for the Caribbean and Central America, and utilized temperature, moisture, mid-level stability, dry air entrainment and an elevation factor to calculate convective potential. In this research, GDI and KI were calculated using Global Forecast System (GFS) …
Rss-Based Device-Free Passive Detection And Localization Using Home Automation Network Radio Frequencies, Tiffany M. Phan
Rss-Based Device-Free Passive Detection And Localization Using Home Automation Network Radio Frequencies, Tiffany M. Phan
Theses and Dissertations
This research provided a proof of concept for a device-free passive (DfP) system capable of detecting and localizing a target through exploitation of a home automation network’s radio frequency (RF) signals. The system was developed using Insteon devices with a 915 MHz center frequency. Without developer privileges, limitations of the Insteon technology like no intrinsic received signal strength (RSS) field and silent periods between messages were overcome by using software-defined radios to simulate Insteon devices capable of collecting and reporting RSS, and by creating a message generation script and implementing a calibrated filter threshold to reduce silent periods. Evaluation of …
Outlier Classification Criterion For Multivariate Cyber Anomaly Detection, Alexander M. Trigo
Outlier Classification Criterion For Multivariate Cyber Anomaly Detection, Alexander M. Trigo
Theses and Dissertations
Every day, intrusion detection systems catalogue millions of unsupervised data entries. This represents a “big data” problem for research sponsors within the Department of Defense. In a first response to this issue, raw data capture was transformed into usable vectors and an array of multivariate techniques implemented to detect potential outliers. This research expands and refines these techniques by implementing a Chi-Square Q-Q plot-based classification criteria for outlier detection. This methodology has been implemented into an R-based programming solution that allows for a refined and semi-automated user experience for intelligence analysts. Moreover, two case analyses are performed that illustrate how …
Characterization Of The Effects Of Heavy Charged Particle Exposure On The Radiation Resistant Bacterium Deinococcus Radiodurans, Todd A. Bryant
Characterization Of The Effects Of Heavy Charged Particle Exposure On The Radiation Resistant Bacterium Deinococcus Radiodurans, Todd A. Bryant
Theses and Dissertations
Although not an extremophile, Deinococcus radiodurans has proven to have exceptional resistance to ionizing radiation, specifically via gamma and X-ray photons. To date, no known experiments have bombarded the bacterium with charged particles larger than hydrogen. This study explored the effects on the organism’s ability to survive high linear energy transfer heavy-charged particle exposures of oxygen ions. It also investigated the effects of low linear energy transfer ultraviolet radiation on various mutants. Two uvrB mutants were created to ascertain the importance of the gene in single-strand break repair following gamma irradiation and two recF mutants were created to explore the …
Mitigating The Effects Of Cyber Attacks And Human Control In An Autonomous Intersection, Karl C. Bentjen
Mitigating The Effects Of Cyber Attacks And Human Control In An Autonomous Intersection, Karl C. Bentjen
Theses and Dissertations
Widespread use of fully autonomous vehicles is near. However, the desire for a human to maintain control, even if limited, of a vehicle will likely never fully subside. Protocols to safely and efficiently manage reservation-based intersections with a mixture of fully autonomous, semi-autonomous, and non-autonomous vehicles exist such as AIM, SemiAIM, and H-AIM. Missing from these protocols is persistent human control of semi-autonomous vehicles in approaching and navigating autonomous intersections without the use of traditional signals. This thesis offers a proof-of-concept of a reservation-based protocol with necessary extensions required for human control in semi-autonomous vehicles. Desired is a protocol that …
Near Earth Space Object Detection Utilizing Parallax As Multi-Hypothesis Test Criterion, Joseph C. Tompkins
Near Earth Space Object Detection Utilizing Parallax As Multi-Hypothesis Test Criterion, Joseph C. Tompkins
Theses and Dissertations
The US Strategic Command (USSTRATCOM) operated Space Surveillance Network (SSN) is tasked with Space Situational Awareness (SSA) for the US military. This system is made up of Electro-Optic sensors such as the Space Surveillance Telescope (SST) and Ground-based Electro-Optical Deep Space Surveillance (GEODSS) as well as RADAR based sensors such as the Space Fence. While Lockheed Martin’s Space Fence is very adept at detecting & tracking objects in Low Earth Orbit (LEO) below 3000 Km in height [1], gaps remain in the tracking of Resident Space Objects (RSO’s) in Geosynchronous Orbits (GEO) due to limitations associated with the implementation of …
Looking Past The Spark To Find The Fuel Of The Arab Spring Fire, Luke M. Brantley
Looking Past The Spark To Find The Fuel Of The Arab Spring Fire, Luke M. Brantley
Theses and Dissertations
The field of statistical conflict prediction addresses region-wide analysis in eras of stable conflict and peace. This study improves upon those prediction rates in times of volatile conflict and peace seen during the Arab Spring of 2011 to 2015. During this time, higher rates of conflict transition in certain Middle Eastern and North African countries occurred than normally observed in previous studies. Due to the fact that previous prediction models decrease in accuracy during times of volatile conflict transition and since the proper strategy for handling the Arab Spring has been highly debated, this study considers alterations to previous studies …
Lightning Prediction Using Artificial Neural Networks And Electric Field Mill Data, Daniel E. Hill
Lightning Prediction Using Artificial Neural Networks And Electric Field Mill Data, Daniel E. Hill
Theses and Dissertations
Electric Field Mills (EFMs) located in the region surrounding Cape Canaveral record the electrification of the atmosphere near them. Research studying how these sensors could improve lightning warnings has had mixed results. This paper used a Convolutional Recurrent Neural Network (CRNN) and data from 30 EFMs from May-July of 2012-2016. The mean was calculated for every 60 second period and 30 minutes of this summarized data was used to create a lightning prediction with a warning period of 15 minutes. This method achieved a True Positive Rate (TPR) of 77.6%, a False Positive Rate (FPR) of 8.3%, a False Discovery …
Plasmonic Grating Geometrics And Wavelength-Dependent Focus Depth In Infrared Detectors, Patrick R. Kennedy
Plasmonic Grating Geometrics And Wavelength-Dependent Focus Depth In Infrared Detectors, Patrick R. Kennedy
Theses and Dissertations
The objective for this research is to determine a relationship between plasmonic grating geometries and the wavelength-dependent focus depth. This research is focused on enhancing the signal collected by infrared detectors by using a metal grating as a planar lens to focus light in the detecting region of the substrate. This can be used to maintain a thinner absorbing region and possibly to create multi-color imaging in a single pixel. Simulations demonstrate that the plasmonic lens is capable of creating a wavelength dependent focus spot.
Quality Of Service Impacts Of A Moving Target Defense With Software-Defined Networking, Samuel A. Mayer
Quality Of Service Impacts Of A Moving Target Defense With Software-Defined Networking, Samuel A. Mayer
Theses and Dissertations
An analysis of the impact a defensive network technique implemented with software-defined networking has upon quality of service experienced by legitimate users. The research validates previous work conducted at AFIT to verify claims of defensive efficacy and then tests network protocols in common use (FTP, HTTP, IMAP, POP, RTP, SMTP, and SSH) on a network that uses this technique. Metrics that indicate the performance of the protocols under test are reported with respect to data gathered in a control network. The conclusions of these experiments enable network engineers to determine if this defensive technique is appropriate for the quality of …
Assessment Of Structure From Motion For Reconnaissance Augmentation And Bandwidth Usage Reduction, Jonathan B. Roeber
Assessment Of Structure From Motion For Reconnaissance Augmentation And Bandwidth Usage Reduction, Jonathan B. Roeber
Theses and Dissertations
Modern militaries rely upon remote image sensors for real-time intelligence. A typical remote system consists of an unmanned aerial vehicle, or UAV, with an attached camera. A video stream is sent from the UAV, through a bandwidth-constrained satellite connection, to an intelligence processing unit. In this research, an upgrade to this method of collection is proposed. A set of synthetic images of a scene captured by a UAV in a virtual environment is sent to a pipeline of computer vision algorithms, collectively known as Structure from Motion. The output of Structure from Motion, a three-dimensional model, is then assessed in …
Characterization Of Ambient Noise, Rachel C. Ramirez
Characterization Of Ambient Noise, Rachel C. Ramirez
Theses and Dissertations
An Air Force sponsor is interested in improving an acoustic detection model by providing better estimates on how to characterize the background noise of various environments. This would inform decision makers on the probability of acoustic detection of different systems of interest given different levels of noise. Data mining and statistical learning techniques are applied to a National Park Service acoustic summary data set to find overall trends over varying environments. Linear regression, conditional inference trees, and random forest techniques are discussed. Findings indicate only sixteen geospatial variables at different resolutions are necessary to characterize the first ten ⅓ octave …
An Analysis Of Multi-Domain Command And Control And The Development Of Software Solutions Through Devops Toolsets And Practices, Mason R. Bruza
An Analysis Of Multi-Domain Command And Control And The Development Of Software Solutions Through Devops Toolsets And Practices, Mason R. Bruza
Theses and Dissertations
Multi-Domain Command and Control (MDC2) is the exercise of command and control over forces in multiple operational domains (namely air, land, sea, space, and cyberspace) in order to produce synergistic effects in the battlespace, and enhancing this capability has become a major focus area for the United States Air Force (USAF). In order to meet demands for MDC2 software, solutions need to be acquired and/or developed in a timely manner, information technology infrastructure needs to be adaptable to new software requirements, and user feedback needs to drive iterative updates to fielded software. In commercial organizations, agile software development methodologies and …
Improving Fallout Characterization By Using Multivariate Techniques To Determine Composition, Christopher R. Pitkins
Improving Fallout Characterization By Using Multivariate Techniques To Determine Composition, Christopher R. Pitkins
Theses and Dissertations
Multivariate statistical techniques have been applied in order to un-mix nuclear fallout debris chemical data. This information is critical to characterization of fallout particle formation following a nuclear detonation. Understanding the correlation between environmental precursors and actinide concentrations in post-detonation nuclear fallout material aids in understanding the physical and chemical processes that alter nuclear device signatures in the fireball. This research examines 123 nuclear fallout samples from a historical nuclear test. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are used to collect chemical compositions of the fallout samples. Principal component analysis (PCA) is applied in order to examine …
Assessing And Expanding Extracurricular Cybersecurity Youth Activities' Impact On Career Interest, Michael H. Dunn
Assessing And Expanding Extracurricular Cybersecurity Youth Activities' Impact On Career Interest, Michael H. Dunn
Theses and Dissertations
This thesis assesses and expands the potential of extracurricular activities to address the shortage of cybersecurity workers by increasing secondary school students’ interest in these careers. Competitions and badges, two forms of gamification often applied in extracurricular educational activities, have potential to improve motivation and increase interest in related careers, but are significantly understudied in the context of cybersecurity activities. CyberPatriot is the largest cybersecurity competition in the United States for secondary school students. Impact on participants’ career interests is assessed by analyzing responses to recent surveys conducted by the competition organizers. Analysis demonstrates significantly increased interest in cybersecurity in …
Securing Critical Infrastructure: A Ransomware Study, Blaine M. Jeffries
Securing Critical Infrastructure: A Ransomware Study, Blaine M. Jeffries
Theses and Dissertations
This thesis reviews traditional ransomware attack trends in order to present a taxonomy for ransomware targeting industrial control systems. After reviewing a critical infrastructure ransomware attack methodology, a corresponding response and recovery plan is described. The plan emphasizes security through redundancy, specifically the incorporation of standby programmable logic controllers. This thesis goes on to describe a set of experiments conducted to test the viability of defending against a specialized ransomware attack with a redundant controller network. Results support that specific redundancy schemes are effective in recovering from a successful attack. Further experimentation is conducted to test the feasibility of industrial …
Expected Coverage (Excov): A Proposal To Compare Fuzz Test Coverage Within An Infinite Input Space, Evan V. Swihart
Expected Coverage (Excov): A Proposal To Compare Fuzz Test Coverage Within An Infinite Input Space, Evan V. Swihart
Theses and Dissertations
A Fuzz test is an approach used to discover vulnerabilities by intentionally sending invalid inputs to a system for the purpose of triggering some type of fault or unintended effect that renders the system vulnerable to an exploit. Fuzz testing is an important cyber-testing technique used to find and fix vulnerabilities before they are exploited. The fuzzing of military data links presents a particular challenge because existing fuzzing tools cannot be easily applied to these systems. As a result, the tools and techniques used to fuzz these links vary widely in sophistication and effectiveness. Because of the infinite, or nearly …
Securing Data In Transit Using Two Channel Communication, Clark L. Wolfe
Securing Data In Transit Using Two Channel Communication, Clark L. Wolfe
Theses and Dissertations
Securing data in transit is critically important to the Department of Defense in todays contested environments. While encryption is often the preferred method to provide security, there exist applications for which encryption is too resource intensive, not cost-effective or simply not available. In this thesis, a two-channel communication system is proposed in which the message being sent can be intelligently and dynamically split over two or more channels to provide a measure of data security either when encryption is not available, or perhaps in addition to encryption. This data spiting technique employs multiple wireless channels operating at the physical layer, …
Modeling Multimodal Failure Effects Of Complex Systems Using Polyweibull Distribution, Daniel A. Timme
Modeling Multimodal Failure Effects Of Complex Systems Using Polyweibull Distribution, Daniel A. Timme
Theses and Dissertations
The Department of Defense (DoD) enlists multiple complex systems across each of their departments. Between the aging systems going through an overhaul and emerging new systems, quality assurance to complete the mission and secure the nation‘s objectives is an absolute necessity. The U.S. Air Force‘s increased interest in Remotely Piloted Aircraft (RPA) and the Space Warfighting domain are current examples of complex systems that must maintain high reliability and sustainability in order to complete missions moving forward. DoD systems continue to grow in complexity with an increasing number of components and parts in more complex arrangements. Bathtub-shaped hazard functions arise …
Analysis Of A Medical Center's Cardiac Risk Screening Protocol Using Propensity Score Matching, Jake E. Johnson
Analysis Of A Medical Center's Cardiac Risk Screening Protocol Using Propensity Score Matching, Jake E. Johnson
Theses and Dissertations
Researchers at the University of Maryland Medical Center in Baltimore have developed a cardiac risk stratification protocol in the hopes of reducing the time-from arrival-to-first-operation for geriatric orthopedic patients. They collected observational data for two years prior to and following the October 2014 implementation of the new screening protocol. Therefore, advanced analytical techniques are required to isolate the treatment effect of the new screening protocol. Propensity score matching (PSM) is used to handle the observational data in order to reduce the bias attributable to the confounding covariates. In addition to PSM, various regression techniques are used to help the researchers …
Variable Speed Simulation For Accelerated Industrial Control System Cyber Training, Luke M. Bradford
Variable Speed Simulation For Accelerated Industrial Control System Cyber Training, Luke M. Bradford
Theses and Dissertations
It is important for industrial control system operators to receive quality training to defend against cyber attacks. Hands-on training exercises with real-world control systems allow operators to learn various defensive techniques and see the real-world impact of changes made to a control system. Cyber attacks and operator actions can have unforeseen effects that take a significant amount of time to manifest and potentially cause physical harm to the system, making high-fidelity training exercises time-consuming and costly. This thesis presents a method for accelerating training exercises by simulating and predicting the effects of a cyber event on a partially-simulated control system. …
Evaluation Of A Cloud Detection Technique Using Spatial And Radiometric Thresholds For Near Infrared Satellite Imagery, William J. Graff
Evaluation Of A Cloud Detection Technique Using Spatial And Radiometric Thresholds For Near Infrared Satellite Imagery, William J. Graff
Theses and Dissertations
Knowledge of cloud location in near infrared (NIR) imagery is of interest to the meteorological community given the wavelengths greater spatial resolution compared to longwave infrared and its potential nighttime applications. This method consists of an algorithm that can be employed by multiple instrument platforms. It analyzes changes between satellite image radiances and a seasonal synthetic background radiance image. The NIR sensor bands of the Sentinel-2 Multispectral Instrument (MSI) and Suomi National Polar-Orbiting Partnership (Suomi NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) satellite instruments are used to evaluate the performance of a monochromatic change detection technique designed to locate areas …
Using An Astrophysical Model To Characterize Nuclear Dust, Anita N. Dunsmore
Using An Astrophysical Model To Characterize Nuclear Dust, Anita N. Dunsmore
Theses and Dissertations
Dust clouds resulting from nuclear explosions are complex phenomena, and knowledge on how they form is lacking. Noting the similarities between supernovae and nuclear explosions led to the concept of modeling a nuclear dust cloud using a supernova simulation. MOCASSIN uses a Monte Carlo approach to model photons traveling through a dust cloud, allowing the cloud's characteristics to be discovered by comparing an observed spectrum to a calculated one and then changing input values to make the spectra match. Data files describing two nuclear fireballs of varying yields were created and analyzed using MOCASSIN, but yielded zero energy spectra. After …
Radiological Decontamination In The Urban Environment Utilizing An Irreversible Wash-Aid Recovery System, Keith A. Sanders
Radiological Decontamination In The Urban Environment Utilizing An Irreversible Wash-Aid Recovery System, Keith A. Sanders
Theses and Dissertations
The radioactive fallout from the Fukushima Daiichi nuclear reactors accident and the ongoing threat of nuclear or radioactive terrorism have forced the need for urban radiological decontamination into the forefront. Many of the established decontamination techniques are not ideally suited for the urban milieu. One of the keys to maximize the effectiveness of long-term remediation and recovery in the urban environment is immediate mitigation within a few days of the incident and before a rain event. The Integrated Wash-Aid, Treatment, and Emergency Reuse System (IWATERS) provides a potentially safe and effective method for early responders and remediation teams to perform …
Comparison Of Plume Dynamics For Laser Ablated Metals: Al And Ti, William A. Bauer, Glen P. Perram, Timothy Haugan
Comparison Of Plume Dynamics For Laser Ablated Metals: Al And Ti, William A. Bauer, Glen P. Perram, Timothy Haugan
Faculty Publications
Emissive plumes from pulsed laser ablation of bulk Ti and Al from KrF laser irradiation at laser fluence up to 3.5 J/cm2 and argon background pressures of 0–1 Torr have been observed using gated intensified charged-coupled device imagery. Mass loss for Ti increases from 0.1 to 0.8 μg/pulse as pulse energy increase from 174 to 282 mJ/pulse (35–170 photons/atom) and decreases by ∼30% as pressure increases from vacuum to 1 Torr. Early plume energies are described by the free expansion velocities of 1.57 ± 0.02 and of 1.81 ± 0.07 cm/μs for Ti and Al, respectively, …