Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Theses and Dissertations

Discipline
Institution
Keyword
Publication Year
File Type

Articles 5191 - 5220 of 30958

Full-Text Articles in Entire DC Network

Modeling Radiation Exposure On Flight Missions To Analyze Aircrew Risk, Camila V. Quintero Hilsaca Mar 2023

Modeling Radiation Exposure On Flight Missions To Analyze Aircrew Risk, Camila V. Quintero Hilsaca

Theses and Dissertations

GCR and SPE comprise the majority of the ionizing radiation experienced in the upper atmosphere within flight-altitude environments. Although previous studies have analyzed radiation doses from single sources on civilian flight operations, there is a lack of research focused on dose received by military personnel during flight from both sources simultaneously. In-flight radiation environments are modeled through the MCNP6 for two separate aircraft, an Air Force A-10 and a Boeing 737. Particle fluence values for galactic cosmic rays and solar particle events for four separate flight paths are determined using the CARI-7A software and the SIRE2 toolkit, respectively. MCNP6 code …

Go to article

Assessment Of Emergency Cooling Requirement For Nuclear Reactor Loss-Of-Coolant Accidents, Michael T. Lindsay Mar 2023

Assessment Of Emergency Cooling Requirement For Nuclear Reactor Loss-Of-Coolant Accidents, Michael T. Lindsay

Theses and Dissertations

The 2022 Russia-Ukraine War marks the first time in modern history of conventional military forces targeting and seizing control of an operational nuclear power plant. Power supply and operational cooling systems are critical to avert reactor loss-of-coolant accidents (LOCA) in the event of emergency shutdown, or SCRAM. A wartime non-design based reactor accident causing loss of reactor power and coolant supply would require an emergency heat exchange via coolant to mitigate reactor core heat. At present, the military does not have a well-defined model which characterizes this requirement for operational planning should such an event occur. SCALE 6.2.4 is used …

Go to article

Modeling The Effects Of Radiation On Microelectromechanical Resonators, David D. Lynes Mar 2023

Modeling The Effects Of Radiation On Microelectromechanical Resonators, David D. Lynes

Theses and Dissertations

As the use of MEMS becomes more prolific in air, space, defense, and power applications, they will be exposed to more extreme radiation environments. This dissertation explores the effects of ionizing and nonionizing radiation on MEMS. AlN-on-Si based piezoelectric bulk acoustic wave resonators were irradiated by gamma-rays and silicon ions while measuring S-parameters in situ. Changes to the resonator and equivalent circuit parameters are extracted. The resonators demonstrated resilience against the effects of radiation-induced charge trapping. However, radiation-induced atomic displacements caused shifts to resonant frequency. From these data, an atomistic model is derived to describe the relationship between radiation type …

Go to article

Environmental Trade-Offs Of Reverse Osmosis Water Purification Units (Rowpus) And Bottled Water, Caleb A. Boone Mar 2023

Environmental Trade-Offs Of Reverse Osmosis Water Purification Units (Rowpus) And Bottled Water, Caleb A. Boone

Theses and Dissertations

The Department of Defense (DoD) conducts many remote missions around the globe. As part of any remote basing strategy, potable water needs to be secured. Currently, there are three primary means of procuring potable water at remote locations: bottled water, on-site purification, or tie-in to existing, local infrastructure. The purpose of this study is to determine the environmental tradeoffs of bottled water and on-site treatment via a Reverse Osmosis Water Purification Unit (ROWPU), which uses multiple levels of filtration to make potable water from freshwater or saline water. A cradle-to- gate assessment was developed for both systems to create a …

Go to article

Topological Variability In Water Distribution Networks, James M. Anderson Mar 2023

Topological Variability In Water Distribution Networks, James M. Anderson

Theses and Dissertations

Water distribution networks are critical infrastructure characterized by difficulties in their assessment and deteriorating performance due to aging components. Resilience analysis of networked infrastructure has replaced traditional risk analysis to focus on performance. Global Resilience Analysis can provide useful information to decision makers and system managers regarding repair and expansion of networks. Network performance has been found to be directly informed by network structure. This work leverages graph theory to assess network qualities that correlate with resiliency characteristics across 69 real world water networks. These networks are then grouped by their structural properties through k-means clustering and compared using parametric …

Go to article

Introvert Personality Labor: A Unique Theoretical Construct That Describes The Effects Of Introverts Existing In The Extrovert Idea, Kathleen S. Hendershott Mar 2023

Introvert Personality Labor: A Unique Theoretical Construct That Describes The Effects Of Introverts Existing In The Extrovert Idea, Kathleen S. Hendershott

Theses and Dissertations

The Extrovert Ideal led to a society that has a favorable bias toward extroverts. Classrooms, workplaces, and the general public have been designed with extroverts in mind. Introverts, who make up more than half the world’s population, are forced to act in extroverted ways due in part to the extrovert ideal. Previous studies indicate introvert performance declines when working with more extroverted preferences, like open offices that favor group work, but fail to discuss the acting introverts are forced to do in workplaces created for their extroverted counterparts. The purpose of this study is to present a unique theoretical construct, …

Go to article

Civilian And Military Civil Engineer Mission In The Space Domain, Linda E. Kuster Mar 2023

Civilian And Military Civil Engineer Mission In The Space Domain, Linda E. Kuster

Theses and Dissertations

Military and civil interest in space-based operations has increased dramatically in recent years due to the discovery of life sustaining properties such as water on Mars and advancements in cyber technology. Civilian sector discussions and research have centered on the establishment of permanent extraterrestrial infrastructure, while discussions from the military perspective have focused on providing reliable, resilient infrastructure, capable of withstanding cyber-based and kinetic attacks. Both perspectives account for known threats and sustainment methods required to ensure success in the space domain. With the existence of threats for the military and civilian missions, civil engineers will undoubtedly be critical to …

Go to article

Defense Industrial Base Mergers And Acquisitions In The Post-Cold War Era, Corey D. Mack Mar 2023

Defense Industrial Base Mergers And Acquisitions In The Post-Cold War Era, Corey D. Mack

Theses and Dissertations

The United States Department of Defense (DoD) relies on prime contractors for weapon system development, acquisition, and sustainability, but the increased consolidation of the Defense Industrial Base (DIB) through mergers and acquisitions (M&A) has raised concerns over reduced competition. This research consists of two studies. The first reviews existing literature to identify factors behind the DIB's increased M&A activity since the 1990s, such as DoD budget cuts and market structure. The second study examines the relationship between a prime contractor's financial health and M&A spending, finding a significant relationship between efficiency and M&A spending. Policymakers can use this information to …

Go to article

Net Zero Water Air Force Installations, Kenneth R. Mcknight Mar 2023

Net Zero Water Air Force Installations, Kenneth R. Mcknight

Theses and Dissertations

The United States continues to face problems of a reduction in quality and quantity of groundwater sources because water extraction exceeds natural source recharge. The Air Force has recognized the importance of these groundwater sources but has put minimal effort into determining their contribution to the depletion of these sources. The purpose of this study is to determine this contribution by determining whether Air Force installations are net zero water. This is done using a geospatial information system to determine the volume of water recharging groundwater sources associated with an Air Force installation. This volume is then compared to the …

Go to article

Sea Level Rise Impacts On Wastewater Treatment Plants And Their Social Vulnerability Differences, David S. P. Robinson Mar 2023

Sea Level Rise Impacts On Wastewater Treatment Plants And Their Social Vulnerability Differences, David S. P. Robinson

Theses and Dissertations

Many of the United States’ major cities that have a high population are located along the coast. The number of people residing in low elevation coastal areas, be-low 10 meters, is increasing. Coastal areas may be affected by various short- and long-term climate hazards, such as sea level rise (SLR). Climate change induced SLR will threaten residents and infrastructure in low-lying coastal areas. A household’s capacity to respond to hazards is highly dependent on its socio-demographic situation which determines its social vulnerability. Wastewater treatment facilities area particularly critical piece of infrastructure often located in low-lying areas due to gravity fed …

Go to article

Decontamination Of Perfluoroalkyl Substances From Stainless Steel Piping Used In Aqueous Film Forming Foam Fire Suppression Systems, Ryan M. Register Mar 2023

Decontamination Of Perfluoroalkyl Substances From Stainless Steel Piping Used In Aqueous Film Forming Foam Fire Suppression Systems, Ryan M. Register

Theses and Dissertations

This study examines the removal of perfluoroalkyl substances (PFAS) from legacy hangar fire suppression systems which utilized PFAS containing aqueous film forming foam (AFFF). Hundreds of these systems are currently in place throughout the Department of Defense, with planned phase-out occurring by 2024. The estimated cost of replacing these systems is $2.1 billion dollars. To mitigate this cost, a triple-rinse method of decontamination has been proposed. This thesis explores the release of PFAS from AFFF systems during a triple-rinse decontamination, and the continued removal of PFAS after a triple-rinse is complete while simultaneously analyzing methylene blue dye as a potential …

Go to article

Long-Term Asset Prioritization To Support District Planning, Melissa R. Sallberg Mar 2023

Long-Term Asset Prioritization To Support District Planning, Melissa R. Sallberg

Theses and Dissertations

The United States Air Force (USAF) relies on its installations to project military power across the globe. However, due to the deferred infrastructure maintenance and recapitalization backlog of $33 billion as of 2019 (Wilson & Goldfein, 2019), it is more critical than ever for base-level community planners to focus their attention to the projects that will achieve each installation’s long-term goals. The recent incorporation of asset management principles into the USAF District Planning Process allows a unique opportunity to improve the existing scoring model for a holistic look at what matters to enterprise leaders and community planners making the plans …

Go to article

Applications Of Fragile Curves To Water Distribution Networks, Danielle M. Van Lanen Mar 2023

Applications Of Fragile Curves To Water Distribution Networks, Danielle M. Van Lanen

Theses and Dissertations

Water distribution networks are of critical importance to provide uninterrupted services to a city. Not only do they provide potable drinking water to customers they also are used for fire services and other emergency support functions. By the year 2039, the United States’ drinking water investment gap is estimated to grow to $136 billion dollars. As the gap between available funding and funding required, being able to prioritize assets for investments is critical. Unfortunately, water distribution networks are typically managed reactively rather than proactively. This paper showcases a methodology for a proactive approach to asset management through the use of …

Go to article

Validation Of Digital System Models, James R. Winton Mar 2023

Validation Of Digital System Models, James R. Winton

Theses and Dissertations

The Department of Defense is undergoing a Digital Transformation driven by Digital Engineering and Model-Based Systems Engineering. Document-based processes are being replaced by digital artifacts, pedigreed data, and an Authoritative Source of Truth for a system across its life cycle. As traditional Design-Build-Test transitions to a Model-Analyze-Build methodology, digital models will proliferate throughout the enterprise and require novel validation processes earlier in the development timeline. A new definition for digital system model validation is proposed to address the identified shortcomings in existing guidance. The proposed validation framework leverages the Systems Modeling Language, use cases, requirements, test cases, and a custom …

Go to article

Information System Availability Status And Its Impact On Customer Wait Times, Joshua A. Cramer Mar 2023

Information System Availability Status And Its Impact On Customer Wait Times, Joshua A. Cramer

Theses and Dissertations

The Military Personnel Flight relies on Air Force Information Systems, specifically the Defense Enrollment Eligibility and Reporting System (DEERS), to manage the personnel records. When DEERS experiences a failure, then the operational ability of the Military Personnel Flight is affected. This study aims at identifying the impact Air Force information system’s availability status has on customer wait times using linear regression.

Go to article

Hierarchical Federated Learning On Healthcare Data: An Application To Parkinson's Disease, Brandon J. Harvill Mar 2023

Hierarchical Federated Learning On Healthcare Data: An Application To Parkinson's Disease, Brandon J. Harvill

Theses and Dissertations

Federated learning (FL) is a budding machine learning (ML) technique that seeks to keep sensitive data private, while overcoming the difficulties of Big Data. Specifically, FL trains machine learning models over a distributed network of devices, while keeping the data local to each device. We apply FL to a Parkinson’s Disease (PD) telemonitoring dataset where physiological data is gathered from various modalities to determine the PD severity level in patients. We seek to optimally combine the information across multiple modalities to assess the accuracy of our FL approach, and compare to traditional ”centralized” statistical and deep learning models.

Go to article

Uncertainty Quantification In Federated Learning For Persistent Post-Traumatic Headache, Byungmoo Brian Kim Mar 2023

Uncertainty Quantification In Federated Learning For Persistent Post-Traumatic Headache, Byungmoo Brian Kim

Theses and Dissertations

A post-traumatic headache (PTH), resulting from a mild traumatic brain injury (mTBI), potentially develops into persistent post-traumatic headache (PPTH). Although no known cure for PPTH exists, research has shown that receiving treatment at earlier stages of PTH lowers the risk of patients developing PPTH. Previous studies have shown machine learning (ML) models capable of predicting a patient’s PTH progression, but none have considered the issue of protecting patient privacy. Due to patient privacy, ML models only have access to data within the institution. Federated learning (FL) harnesses data from separate institutions without sacrificing patient privacy as institutions can run ML …

Go to article

Examining Failures Of Kc-135 Boom Assemblies Using Survival Analysis, Benjamin D. Miller Mar 2023

Examining Failures Of Kc-135 Boom Assemblies Using Survival Analysis, Benjamin D. Miller

Theses and Dissertations

The purposes of this study are to confirm the applicability of survival analysis for predicting recurrent failures of a component of a military aircraft and to provide practical insights to maintenance managers and mission planners. The results of this study also can help the United States Department of Defense improve the CBM+ program. This study was able to predict recurrent failures of the component using Nelson-Aalen cumulative estimates. In addition, this study used a Cox proportional hazards regression model with shared frailty for measuring the effect of covariates on recurrent failures and unidentified heterogeneity in the model, which warranted future …

Go to article

Critical Infrastructure System Resiliency Modeling Using Multi-Layer Network Optimization, Spencer R. Figge Mar 2023

Critical Infrastructure System Resiliency Modeling Using Multi-Layer Network Optimization, Spencer R. Figge

Theses and Dissertations

ccurately modeling the interdependent operation of critical infrastructure systems is an effective and efficient way of proactively evaluating system vulnerabilities and resiliency. Infrastructure systems are designed to transport essential commodities from where they are produced to where they are consumed and network flow-based models are one of the most effective ways to simulate and quantify infrastructure performance. The literature is populated with proposed models that must balance accuracy of interdependent operations, capability to include real-world considerations, and computational cost. This research proposes an alternative network-flow based model called the Critical Infrastructure System Resiliency Model (CISRM) that focuses on modeling a …

Go to article

Perceptions Of Quality Of Healthcare Using A Trauma-Informed Care Perspective Among Trauma Survivors, Jane Axelle Komen Mar 2023

Perceptions Of Quality Of Healthcare Using A Trauma-Informed Care Perspective Among Trauma Survivors, Jane Axelle Komen

Theses and Dissertations

Trauma is an all-too-common occurrence with the potential for several farreaching, deleterious effects both mentally and physically. Several studies have found an association between exposure to trauma and cardiovascular, immune, and musculoskeletal system complications. It has also been linked to chronic pain, cancer, and obesity, in addition to several functional and structural neurological effects. Trauma survivors have also been found to utilize healthcare services at a higher rate than those who have not reported experiencing trauma. Trauma-informed care is a relatively novel concept that has been introduced to increase the sensitivity with which these individuals are treated when attending healthcare …

Go to article

The Effects Of Introversion And Treatment Delivery Modality On Therapeutic Outcomes In A Community Mental Health Clinic, Maria Olga Consbruck Mar 2023

The Effects Of Introversion And Treatment Delivery Modality On Therapeutic Outcomes In A Community Mental Health Clinic, Maria Olga Consbruck

Theses and Dissertations

Objective: The present study examines the effectiveness of teletherapy services for individuals with varying levels of introversion. This study also investigates the comparability of teletherapy to in-person services provided by clinicians in training. Introduction: Virtual platforms, such as teletherapy, have exponentially increased in use by clinicians and community members due to the Covid 19 pandemic. The pandemic has illuminated surprising secondary benefits of teletherapy. Research has shown that teletherapy results in greater accessibility, feasibility, and acceptability of treatment. Teletherapy platforms can reach remote and rural communities, and better address financial and time barriers. Current research indicates that teletherapy services are …

Go to article

Predictors Of Probation Outcome And Recidivism Among Nonviolent Drug Offenders In Mandated Treatment, Kira Elisabeth Johnson Mar 2023

Predictors Of Probation Outcome And Recidivism Among Nonviolent Drug Offenders In Mandated Treatment, Kira Elisabeth Johnson

Theses and Dissertations

Since the early 1990’s, the criminal justice system has been attempting to address the growing numbers of drug crimes and incarcerations resulting from policy decisions meant to discourage drug use and trade. To address resulting overcrowding in the prison system, drug courts and state mandated drug programs were devised to supervise and treat offenders in the community. Many factors have been identified that affect recidivism and related outcome measures for those mandated to drug treatment programs and probation terms, including age, gender, race, duration of treatment, and dosage of treatment. The current study found that age, gender, treatment duration, and …

Go to article

Training Caregivers Of Young Children Who Are Deaf / Hard Of Hearing To Implement Communication Facilitation Strategies, Rachel Lynn Wells Feb 2023

Training Caregivers Of Young Children Who Are Deaf / Hard Of Hearing To Implement Communication Facilitation Strategies, Rachel Lynn Wells

Theses and Dissertations

Caregiver-implemented communication intervention can result in increased communication skills in young children. Parents/caregivers are the first teachers of their children and are in natural positions to provide naturalistic communication intervention throughout their child’s daily life within their home. Professionals who work with young children with communication delays can coach parents in strategies to help facilitate increased communication skills in their children and help incorporate therapeutic techniques into the family’s regular routines. The current study examined the impact of training and coaching on caregivers’ implementation of naturalistic language facilitation strategies with their children who are deaf or hard of hearing using …

Go to article

Shared Reflection On The Perceived Effect Of Culturally Responsive School Leadership On Student Suspension Data In K-8th Grade Chicago Public Schools, Christopher Alan Donald Graves Feb 2023

Shared Reflection On The Perceived Effect Of Culturally Responsive School Leadership On Student Suspension Data In K-8th Grade Chicago Public Schools, Christopher Alan Donald Graves

Theses and Dissertations

Racial discrimination in schools in the U.S. has resulted in a disproportionate number of Black students receiving exclusionary and punitive consequences, in which they are more likely to end up part of the School to Prison Pipeline and less likely to graduate. The researcher completed interviews with eight elementary school principals in Chicago Public Schools whom were identified using publicly available data. All participants were selected for their prior success in reducing the number of Black student suspensions by at least 20% during the years of 2016-2019. The focus of this study was to determine (1) What school leadership practices …

Go to article

The Crafting Of Pre-Service Special Education Teachers’ Perceptions Of Problem Behavior: A Post-Intentional Phenomenological Study, Jamillah Gilbert Feb 2023

The Crafting Of Pre-Service Special Education Teachers’ Perceptions Of Problem Behavior: A Post-Intentional Phenomenological Study, Jamillah Gilbert

Theses and Dissertations

A disproportionate number of Black students with disabilities experience exclusionary discipline practices (e.g., suspensions and expulsions) in K-12 public schools. This disparity persists, regardless of the severity of identified problem behavior, the school’s average socio-economic status, or the type of public school attended. Given that teacher education programs (TEPs) are pivotal training grounds for pedagogical and philosophical formation, it is crucial for TEPs to demonstrate accountability for building critical consciousness of the factors that produce and perpetuate this disparity. Gaining a fuller understanding of how pre-service special education teachers craft their perceptions of problem behavior during their TEPs may help …

Go to article

County-Level Social Determinants Of Health And Covid-19 Health Outcomes, Bret R. Lyman Feb 2023

County-Level Social Determinants Of Health And Covid-19 Health Outcomes, Bret R. Lyman

Theses and Dissertations

Social determinants of health are associated with a variety of negative health outcomes, including COVID-19 morbidity and mortality. However, most research evaluating this relationship have been case studies, retrospective cohort studies, and case series studies and/or have used use analytic techniques, such as linear regression, that can struggle to adequately model the social determinants' complex nature. This study used United States county-level social determinants of health data and March 2020-December 2020 COVID-19 morbidity and mortality data. Structural equation modeling was used to develop a latent measurement model for the social determinants of health. Substantial cross-loadings among the social determinants of …

Go to article

Marginalized Populations And Trauma-Informed Practices At The Secondary Level: Understanding The Connections Between Trauma Exposure And Academic Outcomes Through An Intersectional Framework, Kirsten Hany Feb 2023

Marginalized Populations And Trauma-Informed Practices At The Secondary Level: Understanding The Connections Between Trauma Exposure And Academic Outcomes Through An Intersectional Framework, Kirsten Hany

Theses and Dissertations

This research seeks to understand the relationship between marginalized identities and trauma in adolescents in relation to classroom outcomes, both behavioral and academic, through an intersectional framework. A synthesized review of literature as well as a quantitative study using the HSLS:09 data was conducted to discern how marginalized populations experience trauma in the school environment, and how that trauma impacts academic outcomes. The conclusions drawn through the review of literature and research suggest that marginalized students experience trauma at higher rates as well as disruption of academic outcomes. These conclusions are disseminated in chapter III which is a practitioner piece …

Go to article

Developing Methods For Measuring In Vivo Lipid Metabolism, Russell L. Denton Feb 2023

Developing Methods For Measuring In Vivo Lipid Metabolism, Russell L. Denton

Theses and Dissertations

Lipid metabolism is critically important to the normal function of individual cells and for signaling between tissues of the human body. There is a great need to quantify changes in lipid metabolism because of its implications in both normal healthy conditions and during disease development. In our first study, we developed a liquid chromatography mass spectrometry based workflow to assess in vivo metabolism of murine brain lipids. This involved sample preparation, data acquisition, and analysis software development and improvements. Regarding sample preparation, we maintained the mice at 5% body water for the duration of the experiment. As mouse metabolism proceeds, …

Go to article

Life At The Margins: Regional Inequality In Tunisia And International Migration, Hiba Belhadj Feb 2023

Life At The Margins: Regional Inequality In Tunisia And International Migration, Hiba Belhadj

Theses and Dissertations

Drawing on De Haas’s (2021) argument on migration as a function of people’s aspirations and capabilities, this research examines how regional inequality in Tunisia – affecting both aspirations and capabilities – impacts and shapes the opportunities and outcomes of migration. Building on De Haas’s migration typology, this research will argue that people from marginalized regions undertake “precarious migration.” For this group of migrants, precarity is employed to explain not only their migration but also their employment and livelihood conditions at home. Those from developed regions undertake “free” or “improvement” migration. In a further step, the research examines how these different …

Go to article

Education And Authoritarian Consolidation In Egypt Post 2013, Rola Tarek Feb 2023

Education And Authoritarian Consolidation In Egypt Post 2013, Rola Tarek

Theses and Dissertations

This paper examines how educational changes in school textbooks during a moment authoritarian rebuilding aim to politically demobilize students. This paper investigates how education is a sphere of influence for politics, and how authoritarian consolidation efforts manifest themselves in public and religious education. Focusing on the curricular and textbook changes in Egypt, and using secondary and primary sources the study traces the changing nationalist and religious narratives and how it aids in authoritarian rebuilding.

Go to article

First Prev Next Last