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Articles 1 - 30 of 112
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Understanding And Developing Estimates Based On Practical Foundation Methods For Alaska's Discontinuous Permafrost Region, Paul P. Dennison
Understanding And Developing Estimates Based On Practical Foundation Methods For Alaska's Discontinuous Permafrost Region, Paul P. Dennison
Theses and Dissertations
This research uses a quantitative analysis to develop a family of curves and a calculator for potential foundation thresholds in the discontinuous permafrost region of Alaska. The United States Pacific Command (PACAF) is bolstering the region by advocating for the F-35, KC-46, and the newly proposed long-range bomber to be stationed in Alaska. These next generation aircrafts and warfighters will need new facilities and beddown plans to efficiently and effectively carry out their mission. The biggest obstacle in the region is permafrost; this unique polar phenomenon is found throughout the northern half of Alaska. Fairbanks in particular has multiple military …
Characterization And Scaling Study Of Energy Pathways In Small Four-Stroke Internal Combustion Engines, Jason R. Blantin
Characterization And Scaling Study Of Energy Pathways In Small Four-Stroke Internal Combustion Engines, Jason R. Blantin
Theses and Dissertations
A study of the efficiency and energy losses of a selection of five small (40 - 200 cm3 displacement) single cylinder, four-stroke engines was accomplished. The study was performed as part of a larger effort to improve the range and endurance of small internal combustion engines (ICE) that power Group II Unmanned Aerial Vehicles (UAVs). Little is known about the performance, efficiency, and allocation of energy losses for four-stroke ICEs in this size range. The goal of the study was to characterize these parameters for use in future research efforts. Three research objectives were developed to guide the study …
A Stochastic Model Of Plausibility In Live-Virtual-Constructive Environments, Jeremy R. Millar
A Stochastic Model Of Plausibility In Live-Virtual-Constructive Environments, Jeremy R. Millar
Theses and Dissertations
Distributed live-virtual-constructive simulation promises a number of benefits for the test and evaluation community, including reduced costs, access to simulations of limited availability assets, the ability to conduct large-scale multi-service test events, and recapitalization of existing simulation investments. However, geographically distributed systems are subject to fundamental state consistency limitations that make assessing the data quality of live-virtual-constructive experiments difficult. This research presents a data quality model based on the notion of plausible interaction outcomes. This model explicitly accounts for the lack of absolute state consistency in distributed real-time systems and offers system designers a means of estimating data quality and …
A Location-Aware Middleware Framework For Collaborative Visual Information Discovery And Retrieval, Andrew J.M. Compton
A Location-Aware Middleware Framework For Collaborative Visual Information Discovery And Retrieval, Andrew J.M. Compton
Theses and Dissertations
This work addresses the problem of scalable location-aware distributed indexing to enable the leveraging of collaborative effort for the construction and maintenance of world-scale visual maps and models which could support numerous activities including navigation, visual localization, persistent surveillance, structure from motion, and hazard or disaster detection. Current distributed approaches to mapping and modeling fail to incorporate global geospatial addressing and are limited in their functionality to customize search. Our solution is a peer-to-peer middleware framework based on XOR distance routing which employs a Hilbert Space curve addressing scheme in a novel distributed geographic index. This allows for a universal …
A Tree Locality-Sensitive Hash For Secure Software Testing, Camdon J. Cady
A Tree Locality-Sensitive Hash For Secure Software Testing, Camdon J. Cady
Theses and Dissertations
Bugs in software that make it through testing can cost tens of millions of dollars each year, and in some cases can even result in the loss of human life. In order to eliminate bugs, developers may use symbolic execution to search through possible program states looking for anomalous states. Most of the computational effort to search through these states is spent solving path constraints in order to determine the feasibility of entering each state. State merging can make this search more efficient by combining program states, allowing multiple execution paths to be analyzed at the same time. However, a …
Engineered Surfaces To Control Secondary Electron Yield For Multipactor Suppression, James M. Sattler
Engineered Surfaces To Control Secondary Electron Yield For Multipactor Suppression, James M. Sattler
Theses and Dissertations
A significant problem for satellites, vacuum electron devices, and particle accelerators is multipactor: an avalanche of electrons caused by recurring secondary electron emission (SEE) in a time-varying electric field. The consequences of multipactor range from temporary to permanent device failure. This research studied how surface topography can be engineered to minimize SEE and suppress multipactor. Two new semi-empirical models (one based on a 2D pore, the other based on a 3D pore) were developed to predict the secondary electron yield (SEY) of a porous surface based on pore aspect ratio and porosity. The models were validated with experimental SEY measurements …
Special Features Of The Air-To-Space Neutron Transport Problem, Whitman T. Dailey
Special Features Of The Air-To-Space Neutron Transport Problem, Whitman T. Dailey
Theses and Dissertations
Special features of the air-to-space neutron transport problem are identified, characterized, and quantified to provide information on features that should be included in Monte Carlo simulations to obtain accurate predictions. Currently available codes and tools for Monte Carlo neutron transport calculations do not provide an adequate (in accuracy nor precision nor efficiency) framework for practical transport calculations in the context of the air-to-space neutron transport problem. A new Fortran code, High Altitude Transport to Space for Neutrons (HATS-n), is developed and tested to perform high fidelity Monte Carlo neutron transport calculations for this class of problems. Special features of the …
Effect Of Fused Filament Fabrication Process Parameters On The Mechanical Properties Of Carbon Fiber Reinforced Polymers, Abdulrahman S. Alwabel
Effect Of Fused Filament Fabrication Process Parameters On The Mechanical Properties Of Carbon Fiber Reinforced Polymers, Abdulrahman S. Alwabel
Theses and Dissertations
Carbon fiber reinforced polymer manufactured using additive manufacturing process is relatively a new process. The ability to predict the mechanical properties of these parts with high confidence will spread the use of these high-strength materials in more applications. The purpose of this research was to determine the effect of the build time between successive layers, arrangement of fiber and nylon layers, fiber start location, and the use of support material on the mechanical properties CFRP produced by additive manufacturing process using the MarkForged (MarkOne) 3D printer. A design of experiment (DOE) we preformed to develop a mathematical model describing the …
Oblique Longwave Infrared Atmospheric Compensation, Daniel S. O'Keefe
Oblique Longwave Infrared Atmospheric Compensation, Daniel S. O'Keefe
Theses and Dissertations
This research introduces two novel oblique longwave infrared atmospheric compensation techniques for hyperspectral imagery, Oblique In-Scene Atmospheric Compensation (OISAC) and Radiance Detrending (RD). Current atmospheric compensation algorithms have been developed for nadir-viewing geometries which assume that every pixel in the scene is affected by the atmosphere in nearly the same manner. However, this assumption is violated in oblique imaging conditions where the transmission and path radiance vary continuously as a function of object-sensor range, negatively impacting current algorithms in their ability to compensate for the atmosphere. The techniques presented here leverage the changing viewing conditions to improve rather than hinder …
Evaluating Process Improvement Courses Of Action Through Modeling And Simulation, Joseph R. Owens
Evaluating Process Improvement Courses Of Action Through Modeling And Simulation, Joseph R. Owens
Theses and Dissertations
Quantifying an expected improvement when considering moderate-complexity changes to a process is time consuming and has potential to overlook stochastic effects. By modeling a process as a Numerical Design Structure Matrix (NDSM), simulating the proposed changes, and evaluating performance, quantification can be rapidly accomplished to understand stochastic effects. This thesis explores a method to evaluate complex process changes within Six Sigma DMAIC process improvement to identify the most desirable outcome amongst several improvement options. A tool to perform the modeling and evaluation is developed. This process evaluation tool is verified for functionality, then is demonstrated against generic processes, a case …
Dynamics Of Chemical Degradation In Water Using Photocatalytic Reactions In An Ultraviolet Light Emitting Diode Reactor, John E. Stubbs
Dynamics Of Chemical Degradation In Water Using Photocatalytic Reactions In An Ultraviolet Light Emitting Diode Reactor, John E. Stubbs
Theses and Dissertations
This work examined ultraviolet (UV) light emitting diodes (LED) and hydrogen peroxide in an advanced oxidation process in support of a USAF installation net zero water initiative. A UV LED reactor was used for degradation of soluble organic chemicals. There were linear relationships between input drive current, optical output power, and first order degradation rate constants. When drive current was varied, first order degradation rates depended on chemical identities and the drive current. When molar peroxide ratios were varied, kinetic profiles revealed peroxide-limited or radical-scavenged phenomena. Molar absorptivity helped explain the complexity of chemical removal profiles. Degradation kinetics were used …
Biologically Inspired Network (Bionet) Authentication Using Logical And Pathological Rf-Dna Credential Pairs, Tyrone A.L. Lewis Sr.
Biologically Inspired Network (Bionet) Authentication Using Logical And Pathological Rf-Dna Credential Pairs, Tyrone A.L. Lewis Sr.
Theses and Dissertations
The command and control (C2) of shared space resources are vulnerable to logical credential forgery and impersonation attacks among standardized and interoperable wireless radio frequency (RF) networks. Threats could come from trusted operators (insiders) or from external sources (outsiders). An attacker may gain unauthorized network access and illegally cross into C2 boundaries when conventional network authentication fails. This research proposes an integrated trust management system that uses both application-layer and physical-layer trust markers to authenticate users and their communication sources. In essence, the results from physical-layer RF-DNA fingerprinting techniques are used to improve application-level trust schemes based on command patterns, …
Characterization Of Jet Fuel Combustion Emissions During A C-130 Aeromedical Evacuation Engines Running Onload, Michelle L. Page
Characterization Of Jet Fuel Combustion Emissions During A C-130 Aeromedical Evacuation Engines Running Onload, Michelle L. Page
Theses and Dissertations
The purpose of this research was to characterize jet fuel combustion emissions (JFCE) in an occupational setting. Prior research demonstrated that aircraft emit hazardous species, especially at engine start-up and ground idle. Complaints of eye, nose, and throat irritation from occupational exposures near aircraft exist. In this study JFCE were tested during an aeromedical evacuation engines running patient onload (ERO) on a C-130 Hercules at the 179th Airlift Wing, Mansfield-Lahm Air National Guard. Ultrafine particles, VOC, formaldehyde, carbon monoxide (CO), sulfuric acid, and metals were sampled simultaneously in approximate crew and patient breathing zones. Testing methods were portable condensation …
Luminescence In Lithium Borates, Brant T. Kananen
Luminescence In Lithium Borates, Brant T. Kananen
Theses and Dissertations
Spectrometry methods are used to identify and characterize point defects in single crystals of lithium tetraborate (Li2B4O7) and lithium triborate (LiB3O5) doped with silver or copper, and explore the role of these point defects in luminescence. New defects are identified in Ag-doped including: lithium vacancy substitutional-silver-ion defect-pairs (hole trap); isolated lithium vacancies (hole trap); isolated oxygen vacancies (electron trap); interstitial-silver-ion substitutional-silver-ion defect pairs (electron trap); isolated interstitial silver ions (electron trap); and interstitial-silver-ion lithium-vacancy defect pairs (electron trap). Defect models are proposed, and adjustments made to defect models known defects. …
Three-Dimensional Imaging Of Cold Atoms In A Magneto-Optical Trap With A Light Field Microscope, Gordon E. Lott
Three-Dimensional Imaging Of Cold Atoms In A Magneto-Optical Trap With A Light Field Microscope, Gordon E. Lott
Theses and Dissertations
Imaging of trapped atoms in three dimensions utilizing a light field microscope is demonstrated in this work. Such a system is of interest in the development of atom interferometer accelerometers in dynamic systems where strictly defined focal planes may be impractical. A light field microscope was constructed utilizing a Lytro® Development Kit micro-lens array and sensor. It was used to image fluorescing rubidium atoms in a magneto-optical trap. The three-dimensional (3D) volume of the atoms is reconstructed using a modeled point spread function (PSF), taking into consideration the low magnification (1.25) of the system which changed typical assumptions in the …
Laser Heating Of Graphite And Pulsed Laser Ablation Of Titanium And Aluminum, William A. Bauer
Laser Heating Of Graphite And Pulsed Laser Ablation Of Titanium And Aluminum, William A. Bauer
Theses and Dissertations
Tactical missions for laser weapons include a wide variety of targets, increasing the demands on the laser lethality community. New approaches to reducing the dimensionality of laser and materials interactions are necessary to increase predictive capability. Self-contained systematic experimental study was conducted on continuous wave and pulsed laser interaction with graphite, Al, and Ti. The spectroscopy and plume dynamics from the heating and ablation of these materials was examined to characterize laser weapons effects, develop graphite response for thermal protection systems, and provide optical diagnostics for materials processing. Furthermore, analysis of ablated plume velocity distributions shows application of conventional Maxwell-Boltzmann …
Analysis Of Ar(1s5) Metastable Populations In High Pressure Argon-Helium Gas Discharges, Daniel J. Emmons Ii
Analysis Of Ar(1s5) Metastable Populations In High Pressure Argon-Helium Gas Discharges, Daniel J. Emmons Ii
Theses and Dissertations
Simulations of an argon-helium plasma are performed for two high pressure discharge scenarios to find a uniform, large-volume plasma with Ar(1s5) metastable densities on the order of 1013 cm-3 for use as the ground state in an optically pumped rare gas laser. An analysis of a pulsed direct current discharge is performed for a 7% argon in helium mixture at a pressure of 270 Torr using both zero and one-dimensional models. Kinetics of species relevant to the operation of an optically pumped rare gas laser are analyzed throughout the pulse duration to identify key reaction pathways. Simulations are …
Satellite Propulsion Spectral Signature Detection And Analysis For Space Situational Awareness Using Small Telescopes, Pamela L. Wheeler
Satellite Propulsion Spectral Signature Detection And Analysis For Space Situational Awareness Using Small Telescopes, Pamela L. Wheeler
Theses and Dissertations
Safe satellite operations are of utmost importance. Maintaining precise orbital maintenance places stringent performance requirements on current propulsion systems, which are often electric propulsion systems. Electron temperature is a commonly used diagnostic to determine the performance of a Hall thruster, and recent work has correlated near infrared (NIR) spectral measurements of ionization lines of xenon and krypton to electron temperature measurements. In the research herein, appropriate line spectra ratios are identified for each propellant type when used with remote space-to-ground observations. NIR plume emissions were used to characterize a 600 Watt Hall thruster for a variety of observation angles and …
Optimal Control Methods For Missile Evasion, Ryan W. Carr
Optimal Control Methods For Missile Evasion, Ryan W. Carr
Theses and Dissertations
Optimal control theory is applied to the study of missile evasion, particularly in the case of a single pursuing missile versus a single evading aircraft. It is proposed to divide the evasion problem into two phases, where the primary considerations are energy and maneuverability, respectively. Traditional evasion tactics are well documented for use in the maneuverability phase. To represent the first phase dominated by energy management, the optimal control problem may be posed in two ways, as a fixed final time problem with the objective of maximizing the final distance between the evader and pursuer, and as a free final …
Analysis Of An Experimental Space Debris Removal Mission, Krista L.L. Roth
Analysis Of An Experimental Space Debris Removal Mission, Krista L.L. Roth
Theses and Dissertations
Encountering space debris is an ever-increasing problem in space exploration and exploitation, especially in Low Earth Orbit. While many space-faring governing bodies have attempted to control the orbital lifetime post mission completion of satellites and rocker bodies, objects already in orbit pose a danger to future mission planning. Currently, governments and academic institutions are working to develop missions to remove space debris; however, the proposed missions are typically costly primary missions. This research proposes an alternative to use an upper stage rocket, to be called a chaser, already launching a primary mission near the desired debris as a host for …
Improved Atmospheric Characterization For Hyperspectral Exploitation, Nathan P. Wurst
Improved Atmospheric Characterization For Hyperspectral Exploitation, Nathan P. Wurst
Theses and Dissertations
Airborne hyperspectral imaging (HSI) in the LWIR has shown utility in material detection and identification. This research seeks to determine the most effective methods to perform model-based atmospheric compensation of LWIR HSI data by comparing results obtained from different atmospheric profiles. The standard model for mid-latitude summer (MLS) and radiosonde data are compared to the National Operational Model Archive and Distribution System (NOMADS) numerical weather predictions and the Extreme and Percentile Environmental Reference Tables (ExPERT). The two latter atmospheric profiles are generated using the Laser Environmental Effects Definition and Reference (LEEDR) software. MLS has been a standard starting point for …
Examining Regionalization Efforts To Develop Lessons Learned And Consideration For Department Of Defense Medical Facilities, Erik B. Schuh
Examining Regionalization Efforts To Develop Lessons Learned And Consideration For Department Of Defense Medical Facilities, Erik B. Schuh
Theses and Dissertations
The increase in competition locally and globally has forced companies to become more efficient. One way for companies to gain efficiency is by regionalizing their facilities by either consolidating or collocating to a particular location. A comprehensive literature review addressed the advantages and disadvantages organizations have used in the past when regionalizing. This insight was used on a case study looking at military hospitals in the National Capital Region. The case study was used to find potential cost savings for three surgical procedures by consolidating each procedure to the lowest cost hospital. Future years were then forecasted to find cost …
Application Of Enlisted Force Retention Levels And Career Field Stability, Jamie T. Zimmermann
Application Of Enlisted Force Retention Levels And Career Field Stability, Jamie T. Zimmermann
Theses and Dissertations
The Air Force’s success is influenced by the manpower it has. The end-strength is Congressionally mandated. Predicting personnel retention is critical to the operations of the military. Over 10 years ago, the Air Force produced enlisted career field sustainment lines based on manning. If a career field was over manned the authorizations were decreased, likewise if a career field was under manned the authorizations were increased. The constant fluctuation of manning caused bathtubs to be created and requirements to go unfilled. Currently, the Air Force produces enlisted career field sustainment lines based on the 5-year historical retention rates. This method …
Adsorption Of Perfluorinated Compounds From Post-Emergency Response Wastewater, Christopher T. Schmidt
Adsorption Of Perfluorinated Compounds From Post-Emergency Response Wastewater, Christopher T. Schmidt
Theses and Dissertations
This research investigated the efficacy of granular activated carbon (GAC) as a method to treat water impacted with aqueous film forming foam (AFFF) after a firefighting response. Bench-top experiments were conducted and compared to field scale adsorber performance removing mg/L concentrations of PFAS in water contaminated with Military Specification AFFF. Batch tests compared four adsorbents, and determined Calgon F600 GAC and Rembind Plus mixed carbon media had the greatest perfluorooctane sulfonate (PFOS) capacities. Additional batch isotherm experiments using AFFF and higher PFOS concentrations (mg/L) indicated larger amounts of GAC are required (>30mg/L) for effective removal. Full-scale testing simulated an …
A Framework For Analyzing And Discussing Level Of Human Control Abstraction, Clifford D. Johnson
A Framework For Analyzing And Discussing Level Of Human Control Abstraction, Clifford D. Johnson
Theses and Dissertations
It is often useful to understand the impact of an artificial teammate upon human workload in human-machine teams. Levels of Autonomy (LoA) differentiate systems based on control authority. Unfortunately, human workload is not necessarily correlated with LoA. An alternate classification framework, designated the Level of Human Control Abstraction (LHCA), is proposed. LHCA differentiates system states based on the control and monitoring tasks performed and the level of decisions made by humans. The framework defines five levels, designed to differentiate between system states based upon anticipated levels of human attention. This presentation will summarize the framework and demonstrate its application.
Enhancing The Thermal Performance Of Temporary Fabric Shelters For The Advanced Energy Efficient Shelter System, Justin E. Eshleman
Enhancing The Thermal Performance Of Temporary Fabric Shelters For The Advanced Energy Efficient Shelter System, Justin E. Eshleman
Theses and Dissertations
Investment in the commercial space industry has grown significantly over the past decade. This investment has led to a tremendous leap in capability for small satellite systems and a greater demand for small launch vehicles. At the same time, space system affordability is a point of emphasis within the Department of Defense (DoD) which raises the question: Can the DoD lower space access costs through the exploitation of the growing small satellite and small launch marketplace? We perform a financial analysis of newly developed small launch vehicles delivering a small satellite constellation to low earth orbit (LEO) to perform wideband …
Learning Curves: An Alternative Analysis, Sharif F. Harris
Learning Curves: An Alternative Analysis, Sharif F. Harris
Theses and Dissertations
Learning curves are used to describe and estimate the cost performance of a serial production process. There are numerous different models and methods, however, it is not definitively known which is preferred. The research objective is to performance compare the more common learning curve models. The research goal is improved understanding of the systemic cost drivers of a production process, their relationship to cost, and present modeling methods. The research method is qualitative analysis combined with statistical regression modeling. The research identified that preference for one function or another depended upon the shape of the data and how well a …
Analysis Of Human And Agent Characteristics On Human-Agent Team Performance And Trust, Anthony J. Hillesheim
Analysis Of Human And Agent Characteristics On Human-Agent Team Performance And Trust, Anthony J. Hillesheim
Theses and Dissertations
The human-agent team represents a new construct in how the United States Department of Defense is orchestrating mission planning and mission accomplishment. In order for mission planning and accomplishment to be successful, several requirements must be met: a firm understanding of human trust in automated agents, how human and automated agent characteristics influence human-agent team performance, and how humans behave. This thesis applies a combination of modeling techniques and human experimentation to understand the concepts aforementioned. The modeling techniques used include static modeling in SysML activity diagrams and dynamic modeling of both human and agent behavior in IMPRINT. Additionally, this …
Alternate Stimuli For The Elicitation Of Event-Related Potentials, Bryan V. Jackson
Alternate Stimuli For The Elicitation Of Event-Related Potentials, Bryan V. Jackson
Theses and Dissertations
Brain-Computer Interfaces (BCIs) are systems that leverage user-brain activity to identify and perform specific functions. In applications requiring overt visual attention, focusing on visual stimuli with known temporal variation can elicit measurable changes in brain activity. However, elements of BCI applications can be intrusive. This research was designed to determine if Event-Related Potentials (ERPs), to include Steady-State Visually-Evoked Potentials (SSVEPs), could be elicited and interpreted from less obtrusive stimuli. Specifically, this research explores the use of variable frequency and long-wavelength (infrared) stimuli for SSVEP interpretation to explore the application of less obtrusive stimuli for application in BCIs. It was determined …
An Empirical Analysis Of Air Force Military Construction Project Delivery Method Performance In The United States, Erich C. Kramer
An Empirical Analysis Of Air Force Military Construction Project Delivery Method Performance In The United States, Erich C. Kramer
Theses and Dissertations
The objective of this study is to investigate the performance of the design-bid-build and design-build project delivery methods in Air Force military construction (MILCON). Project delivery performance is measured through quantitative cost, schedule, and change order metrics for 264 design-bid-build and 316 design-build MILCON projects from 2003-2014. The average response measures were statistically compared within each delivery method using three independent variables: time, facility type, and major command (MAJCOM). The historical analysis revealed that the current working estimate programmed amount ratios improved over time for design-build projects, and an overall consistency in schedule growth and project duration performance occurred across …