Digital Commons Network^™

Gender And Persistence In Stem Careers: Predictors And Barriers, Margaret Rose Christie

Theses and Dissertations

In recent years, a great deal of emphasis has been placed on increasing students’ interest in math and science. Specifically, interest in science, technology, engineering, and math (STEM) has been low among students in the United States, and interest seems to be lower among girls than boys. Additionally, increased emphasis has been placed on increasing female representation in STEM careers, as numbers of women in these fields remains disproportionately low compared to men. A variety of factors have been found to increase young people’s interest in STEM, including parent and teacher factors, informal STEM experiences, self-efficacy in math and science, …

Body Mass As The Optimal Load Predictor For Power Clean Variations: A Practical Approach, Marcel Lopes Dos Santos

Theses and Dissertations

The purpose of this study was to examine the possibility of estimating the optimal load of the Hang Power Clean (HPC), Hang High Pull (HHP), and Mid-thigh Clean Pull (MTP) based on a relative percentage of the subjects’ body mass (BM). Fifteen males with experience in weightlifting (age: 21.8 ± 1.9 years; BM: 83.2 ± 9.0 kg; height: 175.4 ± 6.0 cm; 1-repetition maximum [1RM]: 93.0 ± 12.7 kg; 1RM to BM ratio: 1.12 ± 0.13) performed HPC, HHP, and MTP at intensities of 30, 40, 50, 60, 70, 80, and 90% BM. Kinematic data were collected through a 16-camera …

Chilled To The Bone: An Analysis On The Effects Of Cold Temperatures And Weather Conditions Altering The Decomposition Process In Pig ( Sus Scrofa ) Remains, Katharine C. Woollen

Theses and Dissertations

Temperature is one of the most crucial variables affecting the decomposition process, significantly increasing or decreasing the rate at which decomposition occurs. Few studies have been conducted to show how the effects of cold temperatures and weather conditions influence the postmortem interval (PMI). The PMI is defined as the amount of time that has passed since death. The purpose of this study was to evaluate estimations for the PMI when remains are exposed to cold temperatures and weather conditions. Secondly, this study seeks to explain whether variables (i.e., coverings, burial depth, soil pH) can affect the decomposition process during colder …

Kwame Nkrumah, His Afro-American Network And The Pursuit Of An African Personality, Emmanuella Amoh

Theses and Dissertations

This thesis explores the pursuit of a new African personality in post-colonial Ghana by President Nkrumah and his African American network. I argue that Nkrumah’s engagement with African Americans in the pursuit of an African Personality transformed diaspora relations with Africa. It also seeks to explore Black women in this transnational history. Women are not perceived to be as mobile as men in transnationalism thereby underscoring their inputs in the construction of certain historical events. But through examining the lived experiences of Shirley Graham Du Bois and to an extent Maya Angelou and Pauli Murray in Ghana, the African American …

Convolutional Neural Network Architecture Study For Aerial Visual Localization, Jedediah M. Berhold

Theses and Dissertations

In unmanned aerial navigation the ability to determine the aircraft's location is essential for safe flight. The Global Positioning System (GPS) is the default modern application used for geospatial location determination. GPS is extremely robust, very accurate, and has essentially solved aerial localization. Unfortunately, the signals from all Global Navigation Satellite Systems (GNSS) to include GPS can be jammed or spoofed. To this response it is essential to develop alternative systems that could be used to supplement navigation systems, in the event of a lost GNSS signal. Public and governmental satellites have provided large amounts of high-resolution satellite imagery. These …

Micro-Contacts With 3-D Surfaces Made With Grayscale Lithography, Paul L.J. Michaud

Theses and Dissertations

MEMS switches show advantages over FET transistors and PIN diodes for switching applications due to low contact resistance, high linearity, low power use, better isolation and lower insertion loss. The switches have not replaced FETs or PIN diodes due to perceived limitations in their reliability and the need for stable contact resistance. In order to create switches acceptable for industry applications, research on micro-contact physics and failure mechanisms of micro-contacts is necessary to develop durable contact surfaces. The aim of this research was to design and fabricate micro-contacts with three-dimensional surfaces using grayscale lithography. The goal was to create devices …

Event-Based Visual-Inertial Odometry On A Fixed-Wing Unmanned Aerial Vehicle, Kaleb J. Nelson

Theses and Dissertations

Event-based cameras are a new type of visual sensor that operate under a unique paradigm. These cameras provide asynchronous data on the log-level changes in light intensity for individual pixels, independent of other pixels' measurements. Through the hardware-level approach to change detection, these cameras can achieve microsecond fidelity, millisecond latency, ultra-wide dynamic range, and all with very low power requirements. The advantages provided by event-based cameras make them excellent candidates for visual odometry (VO) for unmanned aerial vehicle (UAV) navigation. This document presents the research and implementation of an event-based visual inertial odometry (EVIO) pipeline, which estimates a vehicle's 6-degrees-of-freedom …

Unresolved Object Detection Using Synthetic Data Generation And Artificial Neural Networks, Yong U. Sinn

Theses and Dissertations

This research presents and solves constrained real-world problems of using synthetic data to train artificial neural networks (ANNs) to detect unresolved moving objects in wide field of view (WFOV) electro-optical/infrared (EO/IR) satellite motion imagery. Objectives include demonstrating the use of the Air Force Institute of Technology (AFIT) Sensor and Scene Emulation Tool (ASSET) as an effective tool for generating EO/IR motion imagery representative of real WFOV sensors and describing the ANN architectures, training, and testing results obtained. Deep learning using a 3-D convolutional neural network (3D ConvNet), long short term memory (LSTM) network, and U-Net are used to solve the …

Motivating Airmen To Engage With Technical Education: Experimentation And Analysis Using Modern Gamification Techniques, Landon G.M. Tomcho

Theses and Dissertations

The development and integration of computer systems into today’s society and the subsequent growth of cyber as a warfighting domain has led to changes in military and civilian conflict. Several traits unique to cyber, including disruption and fast pace of change, has led to issues never before seen in the military environment, especially with educating and training. A new approach that leverages crowd-sourced content has been proposed. This approach relies on motivating military members to voluntarily engage with technical (cyber) education. The application of gamification, a design practice aimed at increasing user engagement by targeting core motivators in humans, in …

Improved Fabrication For Micromirror Arrays, Enoc Flores

Theses and Dissertations

Micromirror devices which consisted of one SU-8 2050 layer, two different exposures, and a series of metal depositions were constructed and evaluated. By varying the exposure, a micromirror structure was fabricated with different thicknesses, a ratio of 1.083 µm/(mJ/cm²) was found. The initial design consisted of four layers. The pillar was made of one SU-8 layer, and the top portion had three layers in the following order: gold, SU-8, and gold. This design could not be released and did not have characteristics of a flat and conformal reflective surface. Several variations of the initial design were explored and …

Development Of A Model For 11C Production Via The 14N(P,Α) Reaction Using A Ge Pettrace Cyclotron, Amy C. Hall

Theses and Dissertations

The GE PETtrace 800 Series cyclotron at the Missouri University Research Reactor (MURR) facility is used extensively for medical and research radioisotope production. However, no model exists of its radioisotope production performance, and the energy, full intensity, and spatial profile of the cyclotron proton beam has never been measured. To improve production planning for research and medical isotopes, a MCNP6 model of the isotope production process was developed to maximize efficiency in target design and better understand irradiation conditions. Since the cyclotron beam energy and profile has a significant impact on the types of reactions that take place and the …

Quantifying Uncertainty Of Ensemble Transport And Dispersion Simulations Using Hysplit, Daniel W. Bazemore

Theses and Dissertations

Uncertainty associated with determining the source location of nuclear pollutants in the atmosphere after a nuclear fallout using a numerical model is difficult to determine. Uncertainty can originate from input data (meteorological and emissions), internal model error, physics parameterizations, and stochastic processes. This study uses the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model with data from the 1983 Cross Appalachian Tracer Experiment (CAPTEX) (Ferber et al. 1986) and simulating six nuclear detonations (Rolph et al. 2014) to quantify and communicate uncertainty in ensemble dispersion simulations. This is accomplished by utilizing an ensemble of forward trajectory simulations varying initial conditions …

Variations Of Heavy Ion Abundances Relative To Proton Abundances In Large Solar Energetic Particle Events, Joseph F. Round

Theses and Dissertations

Past studies of heavy ions (Z>2) in large (E>10 MeV/nuc) gradual solar energetic particle (SEP) events have focused on elemental abundances relative to those of a single element, such as Fe or O, and have often neglected ionized H (the primary element used for space weather purposes). This work analyzes SEP abundances in a group of 15 large gradual SEP events from 2000 to 2015 across the energy range of 13.5-50.7 MeV. Hourly flux averages of He, C, O, Mg and Fe from the Advanced Composition Explorer/Solar Isotope Spectrometer (ACE/SIS) are compared to two-hour averages of H flux …

Confidence Inference In Defensive Cyber Operator Decision Making, Graig S. Ganitano

Theses and Dissertations

Cyber defense analysts face the challenge of validating machine generated alerts regarding network-based security threats. Operations tempo and systematic manpower issues have increased the importance of these individual analyst decisions, since they typically are not reviewed or changed. Analysts may not always be confident in their decisions. If confidence can be accurately assessed, then analyst decisions made under low confidence can be independently reviewed and analysts can be offered decision assistance or additional training. This work investigates the utility of using neurophysiological and behavioral correlates of decision confidence to train machine learning models to infer confidence in analyst decisions. Electroencephalography …

Imitating Human Responses Via A Dual-Process Model Approach, Matthew A. Grimm

Theses and Dissertations

Human-autonomous system teaming is becoming more prevalent in the Air Force and in society. Often, the concept of a shared mental model is discussed as a means to enhance collaborative work arrangements between a human and an autonomous system. The idea being that when the models are aligned, the team is more productive due to an increase in trust, predictability, and apparent understanding. This research presents the Dual-Process Model using multivariate normal probability density functions (DPM-MN), which is a cognitive architecture algorithm based on the psychological dual-process theory. The dual-process theory proposes a bipartite decision-making process in people. It labels …

Bio-Based Thiol-Ene Polymer Electrolytes, Elyse Antonia Baroncini

Theses and Dissertations

Industrial and consumer demand for smaller and safer technologies motivates a global research effort to improve electrolytic polymer separators in lithium-ion batteries (LIBs). To incorporate the aromatic structural advantages of lignin, an abundant and renewable resource, into polymer electrolytes, molecules that can be derived from lignin are functionalized and UV-polymerized with multifunctional thiol monomers. Monomer aromaticity, thiol molecular weight, and total functionality are varied, allowing for analysis of the relationships between polymer structure and electrochemical properties.

The synthesized polymers display conductivities on the order of 10^-5 S/cm for gel polymer electrolytes and 10^-4 S/cm for solid polymer electrolytes, comparable to …

Optimal And Robust Neural Network Controllers For Proximal Spacecraft Maneuvers, Brandon Cole George

Theses and Dissertations

Recent successes in machine learning research, buoyed by advances in computational power, have revitalized interest in neural networks and demonstrated their potential in solving complex controls problems. In this research, the reinforcement learning framework is combined with traditional direct shooting methods to generate optimal proximal spacecraft maneuvers. Open-loop and closed-loop feedback controllers, parameterized by multi-layer feed-forward artificial neural networks, are developed with evolutionary and gradient-based optimization algorithms. Utilizing Clohessy- Wiltshire relative motion dynamics, terminally constrained fixed-time, fuel-optimal trajectories are solved for intercept, rendezvous, and natural motion circumnavigation transfer maneuvers using three different thrust models: impulsive, finite, and continuous. In addition …

Analysis Of The Effect Of Corrosion On The Surface Chemistry Of Mild Steel Exposed To Biofuel, Timothy D. Plourde

Theses and Dissertations

The use of biofuels in society is steadily becoming more prevalent. Through this proliferation a concern regarding the role of the fungus Byssochlamys nivea in microbially induced corrosion has surfaced. Through the use of X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscope (SEM) technology, this thesis focused on attempting to determine what effect, if any, Byssochlamys nivea has on the corrosion of mild steel. For this analysis, samples were placed in environments that simulated the conditions of fuel tanks containing the biofuel B20, water, and spores of Byssochlamys nivea for varying lengths of time. However, due to a variety of …

Nitrate Concentrations In Streams As A Function Of Crop Cover In Midwestern Agricultural Watersheds: Assessing The Role Of Corn And Soybeans, Jacob Tyler Piske

Theses and Dissertations

Increased availability and reduced cost of synthetic-nitrogen fertilizers have led to excess nitrogen being deposited in reservoirs. The accumulation of nitrogen (N) in reservoirs has negative effects, generating algal blooms, hypoxic zones, and poor drinking water quality. Corn and soybean utilize nitrogen at different rates, resulting in higher nitrogen fertilizer application to fields for corn than for soybean. This work examines whether the nitrate concentration in a stream may be correlated to the percentage of land devoted to growing corn or soybeans in the watershed. To investigate potential relationships, discharge (Q) and nitrate concentration data from ten USGS gauging stations …

Toxicological Life Cycle Impact Analysis Of Short And Long Chain Perfluorinated Compounds Compared To Impacts Of Treatment Techniques, Joshua R. Glass

Theses and Dissertations

Polyfluoroalkyl substances (PFAS) are man-made substances that are used as surfactants in industrial processes and commercial products most notably for the Air Force in aqueous film-forming foam. These compounds were introduced in the 1950s and have since become pervasive throughout industrial and consumer products such as carpet, leather, and paper as well as textiles that repel water, grease, and oils. As the presence of PFAS continues to grow, so do concerns for the toxicological impacts of exposure to these chemicals. Although there is much research into the toxicological impacts of PFAS, there are no regulatory treatment levels within the United …

A Stochastic Game Theoretical Model For Cyber Security, Michael T. Larkin

Theses and Dissertations

The resiliency of systems integrated through cyber networks is of utmost importance due to the reliance on these systems for critical services such as industrial control systems, nuclear production, and military weapons systems. Current research in cyber resiliency remains largely limited to methodologies utilizing a singular technique that is predominantly theoretical with limited examples given. This research uses notional data in presenting a novel approach to cyber system analysis and network resource allocation by leveraging multiple techniques including game theory, stochastic processes, and mathematical programming. An operational network security problem consisting of 20 tactical normal form games provides an assessment …

An Analysis Of Built Environment Factors In Residences And The Associated Effects On Mental Health Symptoms Of United States Veterans, Cody J. Beemer

Theses and Dissertations

Current awareness and statistics regarding negative mental health outcomes of United States Military and Veteran populations justify research into causes and methods to assist those afflicted. Growing academic research indicates connections between the built environment and the mental health of its occupants may be important. This research is intended to explore this relationship with a Veteran study group. Through the completion of a literature review, key built environment factors associated with various mental health conditions were identified. Mechanisms and pathways through which these factors can affect mental health conditions were explored. An analysis of residential built environment factors and Veteran …

A Life Cycle Analysis Of Dod Expeditionary Waste Management Practices Using Simapro, David J. Chester

Theses and Dissertations

The United States (US) Department of Defense (DoD) is investigating improved municipal solid waste (MSW) management techniques. Current techniques tax already limited land and energy resources at contingency bases and impart additional logistical support requirements and personnel commitments. Seeking a solution to this growing problem, the DoD is investigating waste-to-energy (WTE) systems to reduce the volume of hazardous and non-hazardous solid wastes while generating low emissions. The current barriers to the acquisition and utilization of viable WTE technologies are the high capital and operating and maintenance (O&M) costs. Using the Life-Cycle Analysis (LCA) software SimaPro, the human health, environmental quality, …

Virus Adsorption To Colloids In Water: Interactions Between Bacteriophage Ms2, Kaolinite, And Fiberglass, Ashlee N. Ellis

Theses and Dissertations

Virus adsorption to colloidal particles is an important issue in the water quality community, and it is a particularly important issue for conventional wastewater treatment plants that accept biohazardous waste. Colloids impact the transport of viruses in engineered treatment systems, and they also provide protection against oxidants and other destructive mechanisms. This study evaluated the adsorption of bacteriophage MS2 to colloidal suspensions of kaolinite (KAO) and fiberglass (FG). A series of laboratory batch tests were carried out over a range of experimental conditions to determine kinetic rate constants and characterize bond strength, and computational experiments were done to assess both …

Verification Of Autonomous Systems: Developmental Test And Evaluation Of An Autonomous Uas Swarming Algorithm Combining Simulation, Formulation And Live Flight, Corey A. Combs

Theses and Dissertations

This research was driven by the increase of autonomous systems in the current millennium and the challenging nature of testing and evaluating their performance. A review of the current literature revealed proposed methods for verifying autonomous systems, but few implementations. It exposed several gaps in the current verification and validation methods and suggested goals for filling them. Through the use of modeling, software in the loop (SITL), and flight test, this research verified an autonomous swarming algorithm for unmanned aerial systems (UAS) and validated an exemplar of a testing framework. Thirteen sets of three-vehicle swarm data produced over two days …

Evaluation Of Guar Gum As A Novel Adsorbent, Philicia Geiser

Theses and Dissertations

Guar gum (GG) is a promising product increasingly used in a variety of industries. It is nontoxic, inexpensive, and biodegradable. This research evaluated novel approaches using GG as an adsorbent for aromatic organic water contaminants. The application of GG demonstrated some effectiveness against all contaminants tested. Two brands of GG were tested using 5 different GG treatment strategies. Various experiments demonstrated nearly complete removal of Allura Red dye, Brilliant Blue dye, Erythrosine B dye, Methylene Blue dye, Tartrazine dye, and 2,4-dinitrotoluene; additionally, 78% adsorption was observed for Fast Green dye. GG typically removed less than 10% of toluene, which rapidly …

Electrochemical Modification Of Granular Activated Carbon And Carbon Nanofibers To Determine Effect On Adsorption, Jose E. Martinez Sanchez

Theses and Dissertations

Granular activated carbon and carbon nanofiber samples were tested as is and electrochemically modified to determine the effect on adsorption. An electrochemical cell was used to modify the carbon samples. The samples were then used in bench bottle tests with 2,4-dinitrotoluene (DNT), brilliant blue (BB) dye, and methylene blue (MB) dye solutions and sampled over time intervals. An ultraviolet–visible spectrophotometer was used to analyze the results of the bottle bench tests. The results indicated that electrochemically modified coal-based carbons’ adsorption were improved 25% over the adsorption of the as is carbon samples prior to modification. The electrochemical modification increased adsorption …

Commercialization Analysis Of Sbir Funded Technologies, Theodore A. Rask

Theses and Dissertations

The United States Small Business Innovation Research (SBIR) Program invests $2.2 billion annually into domestic innovation stimulation. The Department of Defense (DoD) contributes almost $1 billion of that investment; of which the Air Force accounts for 25%. Commercialization, either the transfer to programs of record or further industrial investment, is the program’s objective. Data from this research indicates that Air Force programs have a 7.6% commercialization rate; representing an opportunity to improve. Leveraging best practices from industry; this research provides a method to align investments with needed capabilities. This method exploits established user need taxonomies, the DoD Joint Capability Area …

Non-Intrusive Occupancy Detection Methods And Models, James C. Tyhurst

Theses and Dissertations

Occupants in the built environment impact facility energy consumption and indoor air quality. Predicting the presence of occupants within the built environment can therefore be used to manage these factors while providing additional benefits in terms of emergency management and future space utilization. Detecting occupancy requires a combination of sensors and models to accurate assess data collected within facilities to predict occupancy. This thesis investigated occupancy detection through a non-invasive data collection sensors and model. Specifically, this thesis sought to answer two research questions examining the ability of a radial basis function to accurately predict occupancy when generated from data …

United States Air Force Applications Of Unmanned Aerial Systems (Uas): A Delphi Study To Examine Current And Future Uas Autonomous Mission Capabilities, Alberto Sigala

Theses and Dissertations

As UAS technology continues to grow and enable increased autonomous capabilities, acquisition and operational decision makers must determine paths to pursue for existing and emerging mission areas. The DoD has published a number of 25-year unmanned systems integration roadmaps (USIR) to describe future capabilities and challenges. However, these roadmaps have lacked distinguishable stakeholder perspectives. Following the USIRs concept, this research focused on UAS autonomy through the lens of UAS subject matter experts (SMEs). We used the Delphi method with SMEs from USAF communities performing day-to-day operations, acquisitions, and research in UAS domains to forecast mission capabilities over the next 20 …