Digital Commons Network^™

Improvement Of Microcracking And Mechanical Properties Of Tungsten Fabricated Via Laser Powder Bed Fusion Through Alloying With Reactive Secondary Constituents, William S. Mockel

Theses and Dissertations

Tungsten (W), a Group VI transition metal, possesses a number of advantageous properties, most notably its impressive mechanical performance at extreme temperatures. While tungsten's nature render traditional manufacturing methods difficult, additive manufacturing through laser powder bed fusion (LPBF) presents a promising avenue for fabricating tungsten components. However, the material’s high ductile-to-brittle transition temperature combined with the embrittling effect of impurities mean that the residual stresses imparted by LPBF result in microcracking in tungsten, degrading its usefulness. This study sought to improve the characteristics of LPBF-W through the removal of embrittling oxygen content via alloying with low concentrations of reactive elements, …

Design And Evaluation Of A Deployment Mechanism For A Space-Based Origami Mirror In Cubesat Missions, Arturo Luna

Theses and Dissertations

The space environment’s suboptimal lighting conditions and eclipse periods impede inspection and on-orbit servicing missions. To abate this problem, the Air Force Institute of Technology (AFIT) launched the Mirror Illumination for Reconnaissance and Rendezvous of Orbital Resident Systems (MIRRORS) initiative. This initiative provides augmented illumination to resident space objects (RSOs) by reflecting the sun’s rays from a mirror satellite. Leveraging origami-inspired designs for compact packaging, AFIT developed a cube origami flasher mirror constructed from aluminum panels that unfolds passively via Nitinol hinges. This research investigates the necessary deployment and panning mechanisms for a dynamic, space-based origami mirror to advance the …

Mechanical Response Of Triply Periodic Minimal Surface Gyroid Structures Under Combined Loading, Jay B. Patel

Theses and Dissertations

This work explored combined tensile and torsional loads applied to additively manufactured Inconel 718 specimens employing Triply Periodic Minimal Surface (TPMS) structures. The gyroid TPMS unit cell was selected with two variations of cylindrical cell maps, a rectangular cell map, and a spherical cell map. All four variants were tested in an axial-torsion test frame at room temperature using equal parts of vertical and angular displacement control until failure. The combined loading in these tests utilized tension and torsion. The data from the tests were compared to finite element analysis (FEA) models to visualize when yielding was predicted. Finally, the …

Deep Reinforcement Learning For Leo Satellite Grouping, James E. Minteer

Theses and Dissertations

This research investigates jamming evasion using DRL to provide an autonomous solution that repositions a geostationary satellite experiencing directed, terrestrial based jamming. Second, this thesis applies DRL to an area of research for LEO satellite constellations, user grouping, using a portion of an Air Force Research Lab reinforcement learning framework. As LEO satellites orbit the earth, they must constantly re-evaluate not only which users they are able to connect to, but on which of its multiple beams. This model succeeds in finding a balance between maximizing signal strength and minimizing overhead from switching user assignments, all while requiring fewer costly …

An Analytical Approach In Solving A Two-On-One Pursuit Evasion Differential Game With Fast Evader And No-Point Capture, Nathan T. Morrow

Theses and Dissertations

This paper is concerned with a co-planar pursuit-evasion scenario where two Pursuers (P) are after an Evader (E). The players are holonomic/can turn on a dime and their speeds, V_P and V_E, are constant, but the evader is faster than the pursuers, that is, the speed ratio parameter μ =  V_E/V_P > 1. The Pursuers are endowed with a circular capture disc whose radius l > 0. A differential game (DG) with three states and one parameter is addressed through geometric and analytical methods where a partial solution is outlined and visualized. The game is split …

Analyzing Lf/Vlf Lightning Waveforms To Estimate D-Region Electron Density Profiles: Process, Application, And Comparison, William R. Smith

Theses and Dissertations

Lightning waveforms in the low frequency (LF; 30-300 kHz) and the very low frequency (VLF; 3-30 kHz) can be exploited to produce data-driven ionospheric Dregion electron density profile (EDP) estimates with significantly higher spatial and temporal coverage than previously available. The lightning waveforms used in this paper are signals detected in the LF/VLF of negative cloud-to-ground lightning by the Earth Networks Total Lightning Detection Network. Each waveform contains a ground wave and a time-delayed ionospheric reflection. The time delay between the ground wave and ionospheric reflection has previously been used to estimate a single specular reflection altitude, where LF/VLF emissions …

Personal Decontamination Of Copper Oxide Powder As A Radiological Surrogate On Ambulatory Patients In Arctic Environments: Assessing Residual Airborne Risks After Air Shower Or Vacuum Decontamination Of A Manikin, Quinn G. Pelichoff

Theses and Dissertations

This study assessed air-based decontamination methods for treating patients exposed to dry radiological contamination while minimizing reaerosolization during disrobing, particularly in extreme cold environments. A full-size manikin,  simulating an able-bodied Airman, was dressed in military-issue extreme cold weather gear and coated with 28 grams of Copper Oxide. The manikin underwent one of three treatments: HEPA vacuuming, a mobile personal air shower, or no treatment (control). After treatment, researchers removed the uniform and used optical particle counters to measure airborne dust concentrations that could pose risks during disrobing. Each method was tested ten times (30 trials total). Statistical analyses (ANOVA, Tukey’s …

Forecasting Army Recruiting Mission Distribution, Maxwell A. Deihl

Theses and Dissertations

The Army’s recruiting landscape has changed markedly in recent years, raising questions about whether forecasting methods of Army contracts remain robust. This thesis recreates the presented models in Joshua McDonald’s 2015 thesis. It replicates and evaluates the models with updated data (2018–2023) to assess their current validity and compare them to novel alternative approaches, such as simpler regression models or neural networks. While the 2015 model remains a valuable baseline, results suggest that either refining its variables or adopting alternative methods can improve predictive accuracy and interpretability. Ultimately, the United States Army Recruiting Command has many options regarding how it …

Correlating Aerosol Morphology And Optical Properties With Image Blur: An Investigation Of Aerosol-Induced Image Degradation, Patricia A. Byrd

Theses and Dissertations

Small-angle scattering by relatively large cloud/fog droplets and ice crystals is known to degrade imagery. However, it is not well investigated how much of an impact aerosols, especially the prevalent anthropogenic fine/ultra-fine/coarse particles, have in image degradation. This thesis explores the contribution of aerosols to image blur but focuses on collecting field data with a relatively large variety of ambient aerosol characterization and optical instrumentation. Field experiments were conducted over six days, correlating aerosol measurements (particle counters and nephelometer) with image quality from a visible camera along a 450m path. Image blur was quantified using the Modulation Transfer Function (MTF), …

Design, Simulation, And Characterization Of A Deuterated Plastic Scintillator For A Portable Neutron Spectrometer, Anders M. Kinney Ii

Theses and Dissertations

This thesis examines the design, simulation, and experimental characterization of a novel deuterated plastic scintillator for portable neutron spectroscopy applications related to homeland security and nuclear non-proliferation. Using Monte Carlo N-Particle (MCNP) simulations and experimental tests with gamma-ray (¹³⁷Cs) and neutron sources (AmBe, ²⁵²Cf), this research shows that deuterium substitution in scintillators significantly enhances pulse shape discrimination (PSD) and neutron energy spectrum unfolding capabilities. Although deuterated scintillators demonstrate reduced overall light output, their higher stopping power and increased ionization quenching lead to superior neutron event differentiation, particularly between (α, n) and spontaneous fission neutrons critical for detecting …

Performing Requirements Specification And Analysis Through Open Generative Pre-Trained Transformers, Harvey J. Hurst

Theses and Dissertations

Every acquisition program begins with a requirement, and for those programs to succeed, robust requirements engineering (RE) must be implemented. RE encompasses eliciting, analyzing, specifying, and validating requirements—a critical process throughout a program's lifecycle. Despite its importance, RE faces challenges such as scope creep, ambiguity, redundancy, and inadequate automation support, often exacerbated by reliance on historical data. To address these issues, this thesis leverages advancements in Generative Technology, particularly large language models (LLMs) such as Generative Pre-Trained Transformers (GPTs). This research developed two GPT-based tools: the Single Requirement Analysis Tool and the Set of Requirements Analysis Tool. These tools were …

Radiation Assessment And Distribution In Changing Atmospheric Structures And Turbulence (Radcast), Steven B. Hernandez

Theses and Dissertations

The accessibility of materials and online information has made radiological dispersal devices (RDDs) a more probable threat than conventional nuclear weapons. This study analyzed five datasets from three test periods, using a correlation analysis between optical turbulence, aerosol concentration, and environmental parameters, and geometric mean diameter (GMD) calculations. The correlation analysis failed to yield meaningful insights, prompted a transition to the GMD analysis, which produced clearer results. Findings show GMD ranged from 38–41 nm, increasing at night and during neutral events as reduced vertical motion and boundary layer contraction correlated with optical turbulence. An alternative GMD dataset, calculated by the …

What Counselors Say Matters For Supporting High School Newcomer Multilingual Learners As They Work Toward Graduation, Sonia Lucrecia Molina Openshaw

Theses and Dissertations

This thesis explores how high school (HS) counselors describe their work with newcomer multilingual learners (MLs). Using the lens of Yosso’s (2005) Community Cultural Wealth (CCW) framework to identify asset perspectives in their work with these students. They suggest specific supports and barriers impacting these students' academic and social success in school. Findings reveal that counselors often focus on addressing the immediate needs of HS newcomer MLs, such as language acquisition and academic readiness, but less frequently recognize the cultural, linguistic, and social assets students bring to their educational journey. Counselors highlight the importance of systemic supports, including onboarding processes, …

Arabizi (Franco) In Egypt: A Study Of Features, Reasons, Attitudes, And Educational Influence Among Youth In Online Communication, Muhammad Wafa

Theses and Dissertations

This study explores the phenomenon of Arabizi (Franco) as it is employed by Egyptian youth in online communication, focusing on the sociolinguistic factors that influence language choice, particularly educational background. Through a mixed-methods approach, including quantitative analysis of an online questionnaire using inferential statistics and qualitative examination of text samples, this study investigates the most common language varieties used by Egyptian youth, the underlying reasons for Arabizi's adoption, attitudes towards its usage, and the salient features of this variety of online communication. The findings reveal that Arabizi is widely used among Egyptian youth from all educational backgrounds. It is especially …

A Qualitative Study To Determine Teacher Self-Efficacy In Active Shooter Incidents In One Catholic Secondary School, Albert Spiegel

Theses and Dissertations

Active shooter incidents in K-12 schools pose a significant threat to schools throughout the country. Presently, there is a gap in the existing literature regarding the readiness of Catholic secondary school teachers for active shooter scenarios, particularly in terms of assessing their self-efficacy levels for such incidents. The purpose of this qualitative descriptive embedded case study was to determine Catholic secondary school teachers’ sources of self-efficacy in responding to active shooter incidents and to explore how those sources of self-efficacy contributed to teachers’ active shooter preparedness. The aim of this study was to explore the sources of teachers' self-efficacy in …

A Multi-Model And Multi-Agency Approach To Expand The Flood Inundation Mapping Capacity Of The Us National Water Center, Samuel Jay Oldham

Theses and Dissertations

The most accurate numerical model for simulating flood extents of rivers has long been a subject of debate. While specialized models exist for specific hydraulic features, we advocate for the principle that the best model is the one the user is familiar with, has adequate data to support input requirements and limitations, and will consistently employ. To support this approach, we have developed a database schema optimized to store riverine flood inundation model output files. This schema is designed to assist U.S. cities, counties, states, and other flood management agencies in leveraging their existing model-generated flood maps, regardless of the …

Two-Key Dependent Permutation (Tkdp) And Its Applications In Information Security, Arulmani K

Theses and Dissertations

Two-Key Dependent Permutation (TKDP) algorithm for generating permutation sequences of fixed sizes, TKDP based Symmetric Block Cipher (TKDPSBC) and TKDP Audio encryption are being proposed in this thesis. TKDP algorithm is capable of generating different sequences for different key pairs. This makes it suitable for constructing dynamic S-boxes and P-boxes that have more degree of randomness and non-linearity to resist cryptanalytic attacks. Rigorous statistical tests validate the efficacy of the generated permutation sequences, affirming their suitability for cryptographic applications in conjunction with Fiestel network-based block ciphers. TKDPSBC encrypts a plaintext block into a ciphertext block of the same size. TKDP …

Filipino American Parents' Experiences With The United States Special Education System: A Qualitative Study, Greyagail Custodio Surio

Theses and Dissertations

While there have been studies on Asian American (AA) parents' experiences with the U.S. special education (SPED) system, there have been no studies on Filipino American (FA) parents' experiences with the SPED system. As FAs are the third largest Asian group in the United States., there is a need for special education research to be conducted with this population. Interpretative phenomenological analysis (IPA) interviews were conducted over Zoom with FA parents of children receiving SPED services. Participants resided in various states in the United States (n = 10). Participants reported varied and nuanced experiences related to advocacy, working with the …

Navigating Trauma: A Linguistic Exploration Of Bilingual Trauma Expressions, Amira Mahmoud Othman

Theses and Dissertations

This study explores the relationship between language, trauma, and emotional expression among bilingual Arabic-English speakers, focusing on code-switching patterns and euphemisms, and more broadly the emotional roles of native and non-native languages in trauma narratives. Through qualitative interviews with 20 Egyptian participants, the research reveals that code-switching serves as both a linguistic and emotional tool, allowing speakers to navigate trauma by creating distance or engaging more intimately. Such codeswitching patterns include the integration of English content words within Arabic structures, morphosyntactic innovations, and gender agreement applications, reflecting the creative adaptability of bilingual speakers in emotionally charged contexts, in line with …

Social Media’S Influence On Anti-Sexual Harassment Policies In Egypt (2014-2024)900, Yasmine Elleithy

Theses and Dissertations

The study examined the role of social media and women’s online activism in the development of anti-sexual harassment policies in Egypt, specifically from 2014 to 2024. Through employing a qualitative research method involving semi-structured, in-depth interviews, the study engaged different actors, including members of the parliament, the National Council for Women, female online activists, and women’s rights specialists. During this time frame, there has been a remarkable shift in the political, social, and legislative landscape, marked by significant restrictions on traditional activism and the enactment of laws addressing sexual harassment. Throughout this period of unprecedented changes, social media has emerged …

The Role Of Non-Coding Rnas As An Innovative Therapeutic Tool For Hepatocellular Carcinoma, Nabila Mohamed Hosni El Kramani

Theses and Dissertations

Hepatocellular carcinoma (HCC) is the second lethal cancer worldwide, with over 60 million new patients added annually. Hepatitis B infection and toxins, e.g., aflatoxin, contribute to the incidence of HCC. Egypt and China show the highest prevalence of viral hepatitis and HCC in the world.

Long non-coding RNAs (lncRNAs) are non-protein-coding transcripts larger than 200 nucleotides. These transcripts work at the transcriptional, post-transcriptional, and epigenetic levels to regulate gene expression by interacting with various biomolecules, such as RNA, DNA, and proteins. They serve essential functions in chromatin remodeling and cell survival, differentiation, and proliferation. The role and biological interactions of …

Discretion, Deference, And Dysfunction: U.S. Refugee Resettlement From Egypt, Cassandra Mcclellan

Theses and Dissertations

This thesis investigates refugee resettlement from Egypt to the U.S., as facilitated by UNHCR Egypt and the U.S. Refugee Admissions Program (USRAP). Accordingly, the research questions ask what factors determine the volume and profile of refugees UNHCR Egypt submits to USRAP for resettlement, as well as the related determining factors for refugees rejected from and accepted to USRAP. A fourth research question examines the impacts of U.S. refugee policy on the resettlement system in Egypt, including on UNHCR Egypt and refugees. To answer these questions, the thesis first delves into the history of U.S. immigration and refugee policies, with a …

Locked Gates: Japan’S Immigration Quandary In The Face Of Economic And Demographic Realities, Merna Karam Emara

Theses and Dissertations

This study explores Japan's reluctance to accept labor immigrants in the post-World War II era through the analytical lenses of identity politics and historical institutionalism. It examines how Japan’s national identity, emphasizing ethnic homogeneity and cultural preservation, has shaped restrictive immigration policies despite its economic need. Historical institutionalism provides a framework for understanding the persistence of these policies, which are rooted in the institutional legacies of Japan's post-war reconstruction. The research investigates the interplay between identity-based motivations and the institutional structures that constrain policy changes, highlighting how these dynamics have led to the exclusion of foreign labor despite the country’s …

Incorporating Sustainability In Facility Layout Planning Algorithms And Assessing Hybridization Techniques On An Egyptian Case Study, Islam Atia

Theses and Dissertations

Due to the growing consequences faced as a result of global warming and climate change; humanity has come together to take an inclusive stance to combat this serious phenomena and work towards a more sustainable future. Large amounts of carbon dioxide emissions are a major contributor to global warming, and a vast proportion of this emission come from industrial and commercial facilities. Hence, if industrial facilities are built with a larger focus on carbon footprint, it will yield a significant reduction in global emissions throughout the lifetime of the facility and will constitute a huge milestone in the journey to …

Cervical Cancer Screening And Hpv Vaccine Intentions: An Egyptian Population Assessment Through University Channels, Rita Hany Ebeid

Theses and Dissertations

Background: Cervical cancer remains a significant global health burden, disproportionately affecting low- and middle-income countries. While HPV vaccination and cervical cancer screening programs have shown promise in reducing incidence and mortality, access to these interventions remains limited in Egypt. The purpose of this study was to analyze female and male beliefs, knowledge of, and perceptions related to cervical cancer screening and HPV vaccination, and how these factors influence women and men’s intentions to respectively undergo or promote these behaviors in Egypt. This study also aimed to develop recommendations for more effective cervical cancer prevention measures that promote greater uptake among …

Navigating Structural Barriers; Syrians In Cairo, Farah Hamdy Said Abdelghaffar

Theses and Dissertations

This research aims to study the strategies of refugees when they face structural challenges and barriers that hinder them from accessing their rights. The research shall analyze the relationship between the structure and agency of refugees and migrants in order to see how they act in the countries of asylum. The strategies and efforts of refugees will be analyzed in hosting communities that fill in the structural gap that refugees face. The study will focus on the Syrian population in Egypt and how they navigate their daily lives in the Egyptian context despite the lack of an asylum policy in …

National Efforts In Climate Change Adaptation In Agriculture: Assessing Policies And Practices In Egypt’S Nile Delta, Youssef Raafat

Theses and Dissertations

Climate change significantly threatens global security and environmental stability, impacting various sectors, especially the agricultural sector (IPCC, 2021). Climate change has already diminished Egypt’s agricultural productivity by 15 percent (Nassr et al., 2021). In response, the Egyptian government has intensified its efforts to increase agricultural practices adaptation, such as Egypt's 2050 Climate Strategy, the National Water Resources Plan (NWRP 2017-2037), and the NWFE program (NCCS, 2022; NWRP, 2017; NWFE, 2022). Nevertheless, the national policies and efforts remain underexplored in the literature, and their evaluations are not accessible to the public (Grindle, 2017). This research aims to assess the extent to …

Predicting The Indirect Cost Of Construction Projects In Egypt: An Artificial Neural Network Approach, Aya Effat

Theses and Dissertations

Cost estimation is one of the vital processes in construction management that needs to be done early in any project in order to determine the project's budget. The accuracy of the cost estimate is a key factor in the success of construction projects since it enables project managers to successfully control the project’s expenses. Construction costs mainly consist of direct cost and indirect cost. Generally, indirect costs can be categorized into two types: site overheads and general overheads. In a construction project, overheads, particularly site overhead costs, make up a considerable portion of a contractor's budget. Accordingly, accurately estimating the …

Like A Fish Outside The Sea: An Ethnographic Exploration Of Why And How Young Lebanese From El-Mina Migrate To Europe, Lea Farida Studer

Theses and Dissertations

Following the Thawra in 2019, Lebanon’s initial optimism for political change has given way to a harsh reality. The country, troubled by hyperinflation, deteriorating state services, and worsening living conditions, coupled with corruption and sectarianism, is seeing an increasing number of Lebanese seeking alternative futures abroad, including in Europe. Be it via regular or irregular pathways, young Lebanese adults have been leaving the country, their families, their friends – their homes.

This ethnographic Master’s thesis, which was conducted during the Summer of 2023 in El-Mina, a port city in northern Lebanon, delves into the aspirations and capabilities that drive young …

From Home To Abroad: The Intergenerational Impact Of Household Member Migration On Women’S Economic & Social Empowerment In Egypt, Menna Elgohary

Theses and Dissertations

This thesis investigates to what extent the migration of a household member to an Arab country leads to increased social and economic empowerment among Egyptian women of two age categories (15-35 and +35) over two waves. Determined through Principle Component Analysis (PCA) of panel data from Egypt Labor Market Panel Surveys in 2018 and 2023, composite indices of social and economic empowerment serve as dependent variables in an IV 2SLS regression model. The model assesses whether household member migration, proxied by migration prevalence on the district (qism) level as an IV, causes a significant increase in social and economic empowerment …