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Articles 3061 - 3090 of 11510
Full-Text Articles in Engineering
The Effect Of Molar Peroxide Ratio On The Oxidation Of 2,4-Dinitroanisole In An Ultraviolet Light Emitting Diode Advanced Oxidation Process, Troy M. Searcy
The Effect Of Molar Peroxide Ratio On The Oxidation Of 2,4-Dinitroanisole In An Ultraviolet Light Emitting Diode Advanced Oxidation Process, Troy M. Searcy
Theses and Dissertations
Insensitive munitions (IMs) are increasingly employed by the U.S. military to prevent unintended detonations associated with conventional munitions. One IM used extensively is 2,4 dinitroanisole (DNAN). This research employed an ultraviolet light emitting diode (LED) and hydrogen peroxide advanced oxidation process (AOP) to treat DNAN-contaminated water at the laboratory scale. Five molar peroxide ratios (50:1, 100:1, 250:1, 500:1, 1000:1) were evaluated using the observed pseudo first-order rate constant as the performance metric. Both peroxide-limiting reactions and radical scavenging were observed over the range of ratios tested, with overall removal of DNAN decreasing above a ratio of 500:1.
Climate-Informed Prediction And Forecast Modeling Of Installation Total Energy Consumption, Scott C. Weiss
Climate-Informed Prediction And Forecast Modeling Of Installation Total Energy Consumption, Scott C. Weiss
Theses and Dissertations
Climate variability is an external and stochastic factor that causes energy demand uncertainty. Energy managers can use climate-based models to understand future trends of energy demand and to adjust operations, policy, and budgets accordingly. This research focuses on 1) identifying how climate attributes impact energy use, 2) creating a historically informed statistical modeling framework to skillfully predict energy use, and 3) forecasting future changes to energy use and costs, using CMIP5 temperature projections, at the campus level. After synthesizing the existing breadth of research on climate-informed energy modeling, a skillful, unbiased, climate-informed total energy consumption prediction model is developed for …
Aircraft Inspection By Multirotor Uav Using Coverage Path Planning, Patrick H. Silberberg
Aircraft Inspection By Multirotor Uav Using Coverage Path Planning, Patrick H. Silberberg
Theses and Dissertations
All military and commercial aircraft must undergo frequent visual inspections in order to identify damage that could pose a danger to safety of flight. Currently, these inspections are primarily conducted by maintenance personnel. Inspectors must scrutinize the aircraft’s surface to find and document defects such as dents, hail damage, broken fasteners, etc.; this is a time consuming, tedious, and hazardous process. The goal of this work is to develop a visual inspection system which can be used by an Unmanned Aerial Vehicle (UAV), and to test the feasibility of this system on military aircraft. Using an autonomous system in place …
Studying The Conditions For Magnetic Reconnection In Solar Flares With And Without Precursor Flares, Seth H. Garland
Studying The Conditions For Magnetic Reconnection In Solar Flares With And Without Precursor Flares, Seth H. Garland
Theses and Dissertations
Forecasting of solar flares remains a challenge due to the limited understanding of the triggering mechanisms associated with magnetic reconnection, the primary physical phenomenon connected to these events. Consequently, methods continue to rely on the climatology of solar flare events as opposed to the underlying physics principles. Models of magnetic reconnection in the solar atmosphere places the null point of the reconnection within the corona. Though as of now the coronal magnetic field cannot be directly measured, the field is tied to the photospheric magnetic field, which can be. This study utilized data from the Solar Dynamics Observatory Helioseismic and …
Characterization And Analysis Of Bomarc Accident Debris, Aaron J. Heffelfinger
Characterization And Analysis Of Bomarc Accident Debris, Aaron J. Heffelfinger
Theses and Dissertations
Accidents involving nuclear weapons, such as the Boeing Michigan Aeronautical Research Center (BOMARC) accident in 1960, always pose a significant risk of allowing particles composed of nuclear materials to enter the environment. These particles often differ in characteristics and can be of greatly varying sizes. Gamma ray analysis was conducted on the soil sample and radioisotopes within the sample were identified. Two non-destructive methods for locating actinide bearing particles within the sample were testing, resulting in 70 actinide bearing particles ranging from 1-34 microns being identified. These 70 particles underwent both morphological and elemental characterization, indicating uranium and other elements.
Contract Information Extraction Using Machine Learning, Zachary E. Butcher
Contract Information Extraction Using Machine Learning, Zachary E. Butcher
Theses and Dissertations
The Air Force Sustainment Center assisted by the Data Analytics Resource Team and the Defense Logistics Agency collected four million contracts onto one of the Air Force Research Laboratory’s high power computers. This thesis focuses on the effort to determine if parts are available through those contracts. Some information is extracted using machine learning in combination with natural language processing. Where machine learning methods are unsuccessful or inappropriate, text mining techniques, such as pattern recognition and rules, are used. Upon completion, the information is combined into a Gantt chart for quick evaluation. Only 21% of the contracts have their information …
The Obstacles To The Modernization Of Common Support Equipment, J. Erik Ritschard
The Obstacles To The Modernization Of Common Support Equipment, J. Erik Ritschard
Theses and Dissertations
The current fleet of Common Support Equipment (CSE) is faced with a $2B funding disconnect that threatens 9 of the 12 USAF Core Functions. This research identifies the barriers to efforts to modernize CSE across the sustainment, acquisition, and maintenance communities. Using a qualitative, grounded theory methodology, the responses are explored of interviewed Support Equipment managers responsible for the sustainment and modernization of CSE. Significant barriers to current modernization efforts were exposed, resulting in expensive, duplicative, and unreliable equipment; concluding that the AF must change the way CSE is administrated, funded, and culturally understood to prevent future mission degradation.
Defensive Counterair For Air Base Air Defense Using Directed Energy And Kinetic Energy Weapons, Andrew S. Wilson
Defensive Counterair For Air Base Air Defense Using Directed Energy And Kinetic Energy Weapons, Andrew S. Wilson
Theses and Dissertations
Air bases in key locations provide a strategic advantage to the countries that access them, and are at constant threat from adversaries. This research seeks to determine the optimal maneuvering of a fixed number of fighter aircraft in a combat air patrol for defensive counterair to maximally and effectively attrit the inbound cruise missile threat to a stationary high value asset such as an air base. The problem formulation identifies multiple objectives for the model: minimize the distance traveled for the fighters, minimize the time utilized to engage the incoming cruise missiles, and maximize the number of cruise missiles destroyed. …
Developing Infrastructure Adaptation Pathways To Combat Hurricane Intensification: A Coupled Storm Simulation And Economic Modeling Framework For Coastal Installations, Alexander J. Baldwin
Developing Infrastructure Adaptation Pathways To Combat Hurricane Intensification: A Coupled Storm Simulation And Economic Modeling Framework For Coastal Installations, Alexander J. Baldwin
Theses and Dissertations
Climate change projections suggest intensification of extreme weather events, including hurricanes, is expected throughout the 21st century. This will lead to increased destruction for coastal military bases unless infrastructure resiliency and adaptation measures are implemented. This research focuses on examining the simulation of probabilistic, climate-intensified hurricane events at Eglin Air Force Base. FEMA Hazus models are combined with climate projections for wind Intensity, tide, and sea-level rise to produce an assessment of losses to the installation. Damage estimates and hurricane intensity outputs are downscaled to the facility-level so that climate adaptation signals can be identified. The facility losses and climate …
Guidance For Building Motivation In Space Operator Training, Foster E. Davis
Guidance For Building Motivation In Space Operator Training, Foster E. Davis
Theses and Dissertations
Services provided by spacecraft, including communications and global positioning, are integral to small businesses, multinational corporations, and the United States Department of Defense. United States rivals recognize the need to undermine the military advantage provided by the space domain and are exploring ways to degrade these services in their warfare doctrine. In response, the United States will need space systems suited to counter these threats and personnel who are trained to respond to the new reality of a contested space environment. This paper also reviews the academic literature and written guidelines for developing motivation in an interactive environment for improving …
Modeling Situation Awareness In A Uav Scenario Using Sysml, Tommy R. Hernandez
Modeling Situation Awareness In A Uav Scenario Using Sysml, Tommy R. Hernandez
Theses and Dissertations
The U.S. Department of Defense (DoD) is rapidly moving towards using increasingly automated systems. Unmanned Aerial Systems (UAS) will be used in contested environments where direct human control may be impossible for long stretches of time. This increase in automation brings with it challenges in maintaining resilient Situation Awareness (SA) for operators, who still need to set goals for the UAS to accomplish their missions. Simultaneously, the DoD is increasing the adoption of Model-Based Systems Engineering (MBSE) in the development of weapon systems. This thesis explores the use of SysML to model of an SA repair system for a UAS …
Robust Scandium Aluminum Nitride Mems Resonators For L Band Operation In Orbital Environments, Israel W. Dunk
Robust Scandium Aluminum Nitride Mems Resonators For L Band Operation In Orbital Environments, Israel W. Dunk
Theses and Dissertations
This thesis investigates AlN alloyed with scandium in a variety of resonator architectures including WEM, overtone WEM, LEM, and SAW that have the potential to achieve high levels of electrical performance and environmental robustness. SAW resonators operating near 370 MHz are fabricated on polycrystalline Sc.37Al.63N, and AlN with the resulting devices compared and conclusions drawn as to the merits of each material. The design and fabrication of SAW devices is discussed in detail, with the operating characteristics of these resonators then tested both electrically and mechanically. Mechanical characterisation includes analysis of vibration and shock effects on …
Error Reduction For The Determination Of Transverse Moduli Of Single-Strand Carbon Fibers Via Atomic Force Microscopy, Joshua D. Frey
Error Reduction For The Determination Of Transverse Moduli Of Single-Strand Carbon Fibers Via Atomic Force Microscopy, Joshua D. Frey
Theses and Dissertations
The transverse modulus of single strand carbon fibers is measured using PeakForce Atomic Force Microscopy - Quantitative Nanomechanical Measurement to less than 5 percent error for 11 types of carbon fiber with longitudinal moduli between 924-231 GPA, including export-controlled fibers. Statistical methods are employed to improve the quality of data to exclude outliers within an measurement and within the sample set. A positive linear correlation between the longitudinal and transverse modulus with an R2=0.76 is found. Pitch-based fibers exhibit lower measurement error than PAN-based fibers, while PAN fibers exhibited no apparent modulus correlation when the Pitch fibers are …
Examining The Impact Of Logistics On Military Strength Among East Asian Nations Using Data Envelopment Analysis, Meaghan E. Crandell
Examining The Impact Of Logistics On Military Strength Among East Asian Nations Using Data Envelopment Analysis, Meaghan E. Crandell
Theses and Dissertations
The current narrative in logistics revolves around modernization and the rapid development and deployment of capabilities, which is a sentiment echoed across the Air Force and the DoD alike. However, the combination of intangible and tangible aspects of logistics can make it challenging to find a foundational place to start the process. The purpose of this study is to evaluate logistical factors to include land area, infrastructure, labor force, and GDP and their relationship to military power. This foundation will provide a baseline of areas for improvement and replication. Data Envelopment Analysis (DEA) and linear regression were leveraged to analyze …
Examining Military Cargo Pilots' Eco-Friendly Flying Intention, Ioan A. Gaitan
Examining Military Cargo Pilots' Eco-Friendly Flying Intention, Ioan A. Gaitan
Theses and Dissertations
The US Air Force is the largest operational energy consumer within the Department of Defense primarily due to aviation fuel use. Military pilots can play important roles in saving aviation fuel by flying aircraft in an eco-friendly manner. According to the theory of planned behavior (TPB), intention is the major predictor of behavior. This study tests two models based on TPB for understanding cargo pilots’ eco-friendly intentions when they conduct channel or logistics missions. The study found that attitude, subjective norm, and perceived behavior control were significant antecedents to intention in a multiple regression with aggregated scales.
Enumerating And Locating Bluetooth Devices For Casualty Recovery In A First-Responder Environment, Justin M. Durham
Enumerating And Locating Bluetooth Devices For Casualty Recovery In A First-Responder Environment, Justin M. Durham
Theses and Dissertations
It is difficult for first-responders to quickly locate casualties in an emergency environment such as an explosion or natural disaster. In order to provide another tool to locate individuals, this research attempts to identify and estimate the location of devices that would likely be located on or with a person. A variety of devices, such as phones, smartwatches, and Bluetooth-enabled locks, are tested in multiple environments and at various heights to determine the impact that placement and interference played in locating the devices. The hypothesis is that most Bluetooth devices can be successfully enumerated quickly, but cannot be accurately located …
Stochastic Programming Design For West Africa Logistics Networks, Julius C. Walker
Stochastic Programming Design For West Africa Logistics Networks, Julius C. Walker
Theses and Dissertations
The USAFRICOM is studying methods to increase the resiliency of its West African Logistic Network, a hub-and-spoke network design responsible for sustaining long term humanitarian and security missions in the West Africa region. This paper employs a two-stage stochastic programming network design modeled on the WALN that builds a flexible supply chain capable of responding to periodic disruptions while maintaining peak resiliency. Elements such as cost, probability, and event-based disruption are integrated into the model to mirror challenges the WALN faces. We demonstrate that incorporating resilient based response mechanism provide a 90% reduction in cost compared to meeting the logistical …
Resilient Maintenance Infrastructure: Dynamic Repair Network Designs To Effectively Manage Supply Chain Disruptions, David W. Wallace Iii
Resilient Maintenance Infrastructure: Dynamic Repair Network Designs To Effectively Manage Supply Chain Disruptions, David W. Wallace Iii
Theses and Dissertations
Supply chains are facing numerous changes contributing to their increase in complexity and vulnerability to disruptions. Subsequently, decision-makers lack a transparent, generalizable tool to quantify supply chain resilience and assess additional resilience investments. This research facilitates a more profound understanding of the intricacies and interrelation of supply chain nodes and constructs. It integrates the Area under the Curve (AUC) metric to quantify performance or any organizational measure of competitive advantage amid a disruption. Due to its structural resemblance to various organizational platforms, the subset United States Air Force (USAF) F-16 engine repair and supply network is modeled employing discrete-event simulation. …
A Simulation Modeling The Effects Of Maintenance Personnel On Aircraft Sortie Generation, Benjamin D. Huffman
A Simulation Modeling The Effects Of Maintenance Personnel On Aircraft Sortie Generation, Benjamin D. Huffman
Theses and Dissertations
Commanders and wargamers lack adequate tools to quickly determine the number of mission-capable (MC) aircraft and number of achievable sorties to support wargames and exercises. Even less understood is the impact of available maintenance personnel on sortie generation. The Expected-Number-of-In-Game-Mission-capable Aircraft (ENIGMA) simulation was recently developed to calculate the number of MC aircraft and number of sorties own accounting for the number and type of aircraft, scheduled sorties, mean-time-between-failure (MTBF), and mean-time-to-repair (MTTR). ENIGMA is extended by replacing the MTTR input with functions derived from actual numbers and types of maintenance personnel available. Functions in the form of response surface …
Static Fatigue Of Hi-Nicalon™ S Ceramic Fiber Tows At 600°C In Air And Silicic Acid-Saturated Steam, Caleigh M. Nelson
Static Fatigue Of Hi-Nicalon™ S Ceramic Fiber Tows At 600°C In Air And Silicic Acid-Saturated Steam, Caleigh M. Nelson
Theses and Dissertations
Ceramic matrix composites (CMCs) have the potential to be utilized in applications such as hypersonic vehicles, aircraft leading edges, hot sections of engines, and rocket nozzles. Of particular interest are advanced SiC/SiC composites that can withstand the elevated temperatures and harsh oxidizing environments while maintaining their properties and structural integrity under an applied load. Steam, a major component of combustion environment, is one such aggressive oxidizing environment. As steam passes through the SiC/SiC composite, entering the composite interior through the cracks in the SiC matrix, it becomes saturated with silicic acid, Si(OH)4. Before incorporating SiC/SiC composites in the …
An Analysis Of Application Type, Super Domain, And Productivity In Software Intensive Defense Acquisition, Evan P. Amato
An Analysis Of Application Type, Super Domain, And Productivity In Software Intensive Defense Acquisition, Evan P. Amato
Theses and Dissertations
The productivity of software developers has been an area of interest in the private industry in an endeavor to more appropriately interpret pertinent software development cost drivers. In an effort to better predict the cost of developing software, many have focused on Application Type as an important factor. The Department of Defense (DoD) has recently adopted a similar focus. Studies on categorization schemes of Application Types have shown increasingly relevant cost and productivity driving characteristics recently in the DoD. Identification of factors associated with distinct productivity effects is important for the defense acquisition and software cost estimation domains. Distinct factors …
Optimal Defense Of High Value Airborne Assets, Isaac E. Weintraub
Optimal Defense Of High Value Airborne Assets, Isaac E. Weintraub
Theses and Dissertations
Optimal control theory and differential game theory is applied to the study of the defense of high value airborne assets, particularly in the case of a single threat such as an adversarial aircraft or missile. Rather than utilizing onboard defenses of the high value airborne asset, defense is proposed using a teamed unmanned combat air vehicle. The common scenario throughout this dissertation involves the defense of a high value airborne asset (evader) teamed with an unmanned combat vehicle (defender) against a single threat (pursuer). The unmanned combat air vehicle (defender), provides defense in one of two ways: kinetic or directed …
Hybridized Spacecraft Attitude Control Via Reinforcement Learning Using Control Moment Gyroscope Arrays, Cecily C. Agu
Hybridized Spacecraft Attitude Control Via Reinforcement Learning Using Control Moment Gyroscope Arrays, Cecily C. Agu
Theses and Dissertations
Machine learning techniques in the form of reinforcement learning (RL) can solve complex nonlinear problems found within spacecraft attitude determination and control systems (ADCS). Three CMG arrays were implemented in two simulated spacecraft environments using a reinforcement learning controller. The performance of the controllers were evaluated using target profiles from traditional control law implementations, singularity measure, and variable initial state values. The current research demonstrates that while RL techniques can be implemented, further exploration is needed to investigate the operational efficacy of an approach for producing comparable performance attributes with respect to traditional control laws.
A Framework For Autonomous Cooperative Optimal Assignment And Control Of Satellite Formations, Devin E. Saunders
A Framework For Autonomous Cooperative Optimal Assignment And Control Of Satellite Formations, Devin E. Saunders
Theses and Dissertations
A decentralized, cooperative multi-agent optimal control framework is presented to offer a solution to the assignment and control problems associated with performing multi-agent tasks in a proximity operations environment. However, the framework developed may be applied to a variety domains such as air, space, and sea. The solution presented takes advantage of a second price auction assignment algorithm to optimally task each satellite, while model predictive control is implemented to control the agents optimally while adhering to safety and mission constraints. The solution is compared to a pseudospectral collocation method, and a study on tuning parameters is included.
Deep Reinforcement Learning Applied To Spacecraft Attitude Control And Moment Of Inertia Estimation Via Recurrent Neural Networks, Nathaniel A. Enders
Deep Reinforcement Learning Applied To Spacecraft Attitude Control And Moment Of Inertia Estimation Via Recurrent Neural Networks, Nathaniel A. Enders
Theses and Dissertations
This study investigated two distinct problems related to unknown spacecraft inertia. The first problem explored the use of a recurrent neural network to estimate spacecraft moments of inertia using angular velocity measurements. Initial results showed that, for the configuration examined, the neural network can estimate the moments of inertia when there is a known external torque. The second problem trained a reinforcement learning agent, via proximal policy optimization, to control the attitude of a spacecraft. The results demonstrated that reinforcement learning may be a viable option for guidance and control solutions where the spacecraft model may be unknown. The trained …
Mechanical Properties And Performance Of A Novel Nano-Engineered Unitized Composite For Aerospace Systems, Benjamin C. Lam
Mechanical Properties And Performance Of A Novel Nano-Engineered Unitized Composite For Aerospace Systems, Benjamin C. Lam
Theses and Dissertations
Carbon nanotubes (CNTs) exhibit outstanding mechanical properties, such as exceptionally high tensile stiffness and strength, combined with excellent electrical and thermal characteristics. This research investigates the mechanical properties and performance of a newly developed hybrid nano-engineered composite. The carbon fiber/polymer matrix composite incorporates a forest of vertically aligned CNTs, called NanoStitch, between the prepreg plies. Basic tensile properties of both material systems were investigated for both on-axis [0/90] and off-axis [±45] fiber orientations at room temperature. Tension-tension fatigue tests were performed with a frequency of 1.0 Hz and a ratio of minimum stress to maximum stress of R= 0.05. Fatigue …
Performance Analysis Of Long-Term Evoluution Signals In Passive Bistatic Radar Applications Using Reduced Dimension Space-Time Adaptive Processing Techniques, Sureshan Suntharalingam
Performance Analysis Of Long-Term Evoluution Signals In Passive Bistatic Radar Applications Using Reduced Dimension Space-Time Adaptive Processing Techniques, Sureshan Suntharalingam
Theses and Dissertations
Widespread availability of long term evolution (LTE) signals makes them potential for use in passive bistatic radar (PBR) applications. However, their utility in such applications is yet to be fully explored. This research focuses on the key LTE signal attributes, such as subcarrier modulation schemes and bandwidth, and their effect on PBR application. space-time adaptive processing (STAP) concepts, both full dimension STAP (FD-STAP) reduced dimension STAP (RD-STAP), were employed to evaluate and compare the effects of varying these signal attributes, in terms of signal to interference-plus-noise ratio (SINR) loss metrics. Simulation results concluded that decreasing LTE signal's bandwidth and increasing …
Density Measurements Of Neutral Xenon Using Multiphoton Ionization And Microwave Spectroscopy In A Hall Effect Thruster, Taylor J. Foy
Density Measurements Of Neutral Xenon Using Multiphoton Ionization And Microwave Spectroscopy In A Hall Effect Thruster, Taylor J. Foy
Theses and Dissertations
A new dye laser and microwave scattering system for measuring low speed xenon particles was installed to characterize a commercially sourced 600 W Hall effect thruster. The new system uses multiphoton ionization and microwave spectroscopy to determine number density and velocity measurements of neutral xenon atoms in the plume of a Hall thruster. A study was conducted to ensure the new system will be able to accurately measure these neutrals in future work. The ultimate goal of this new system is to isolate and characterize the extra thrust produced in Hall Effect Thrusters due to finite volume vacuum chambers.
Fatigue Of Two Oxide/Oxide Ceramic Matrix Composites At 1200°C In Air And In Steam. Effect Of Diamond Drilled Effusion Holes, Anthony R. Cabri
Fatigue Of Two Oxide/Oxide Ceramic Matrix Composites At 1200°C In Air And In Steam. Effect Of Diamond Drilled Effusion Holes, Anthony R. Cabri
Theses and Dissertations
The tension-tension fatigue behavior of two oxide-oxide ceramic matrix composites (CMCs) was investigated at 1200°C in laboratory air and steam. Both composites consist of a porous oxide matrix reinforced with laminated, woven mullite/alumina (NextelTM720) fibers. The first composite had an alumina matrix, while the second had an alumina-mullite matrix. First, we assessed the effects of incorporating mullite into the matrix material on fatigue performance by studying the tension-tension fatigue behavior of alumina-mullite matrix CMC. Second, we evaluated the effects of effusion holes on the alumina matrix CMC's fatigue performance. Specimens containing an array of 17 effusion holes of 0.5-mm diameter …
A Survey Of The Strategic Alternate Sourcing Program Offices Management Of United States Air Force Diminishing Manufacturing Sources And Material Shortages Subject Matter Experts, David E. Portée
Theses and Dissertations
The office designated by the Air Force to be DMSMS subject expert program office is known as the Strategic Alternate Sourcing Program Office (SASPO). Aided by the USAF Program Offices and DMSMS Subject Matter Experts, the SASPO is responsible for sourcing DMSMS resolutions as well as the organizing, training, and equipping of the Program Offices DMSMS Programs. Using quantitative research, this study conducts a survey, with the USAF Program Offices as the unit of analysis, to gain insight as to where the SASPO is doing well and where gaps exist in their program management. The analysis and conclusion identify where …