Digital Commons Network^™

Process-Structure-Property Relationships In Laser Powder Bed Fusion Produced 17-4 Ph Steel, Ben Brown

Doctoral Dissertations

Laser powder bed fusion (LPBF) is a metal additive manufacturing method that produces non-traditional microstructures as a result of the rapid solidification and thermal cycling inherent to the process. When using LPBF-produced material in application, these unique microstructures challenge the applicability of well-developed mechanical property databases achieved by conventional heat treatments. For wider adoption of this technology, a more holistic understanding is necessary on how process attributes develop material structure, which dictate mechanical properties. This dissertation explores the process structure-property relationships in LPBF 17-4 PH steel through systematic evaluation of atmospheric processing and heat treatment effects on microstructure and mechanical …

Digital Transformation Of The Maritime Labour Law : Srems Complaints & Claims Legal, Digital Solution, Case Study Of Morocco, Rida El Missaoui

World Maritime University Dissertations

This Master’s dissertation investigates the strong need to reform and digitalize the mechanisms of monitoring and follow-up of the on-board compliance on seafarer’s rights and obligations through a legal-digital tool.

Application Of Artificial Intelligence Techniques To Improve Leadership Decision Making With Uncertainty, Michael David Parrish

Doctoral Dissertations

"Every good leader is a good manager, but not every good manager is a good leader. The difference between the leader and the manager is critical decision-making. Today’s decision-making environment is characterized as Volatile, Uncertain, Complex, and Ambiguous (VUCA). With the exponential increase in the technical capabilities of systems, the human has become the weakest link in the use of such systems. To remain relevant, good leaders must continuously adapt to new advances in technology and processes.

The research contributions of this work provide several unique and novel solutions for leaders to utilize artificial intelligence tools to improve and optimize …

Raft-Based Polymer And Nanoparticle Materials For Traumatic Brain Injury Treatment And Diagnostics, Aaron Priester

Doctoral Dissertations

"Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Neurodegenerative diseases that develop post-TBI can be, in part, attributed to DNA and cell-damaging reactive oxygen species (ROS) and lipid peroxidation products (LPOx). This thesis focused on overcoming the limits of current TBI material treatment approaches by employing a RAFT (reversible-addition fragmentation chain transfer) polymer approach that incorporated novel therapeutic, diagnostic and peptide-targeting monomers. An improved nanoparticle synthesis approach was also developed. Thiol and thioether-containing monomers neutralize both ROS and LPOx while Gd-containing monomers with enhanced magnetic resonance imaging (MRI) contrast provide diagnostics and material tracking in …

Atmospheric Transport Of Radionuclides, Meteorological Data Mining & Synthesis For Site Data Supplementation, Ben Yao Sonpon

Doctoral Dissertations

"This research aligns with the NRC's vision of implementing risk-informed decision-making to support its regulatory charter. The suite of tools developed includes automated procedures for data mining and extracting meteorological (met) data from various national and regional repositories. A second data analytics tool automates the process of data fusion into a uniform format while preserving data fidelity. Autocorrelations were then established, and correlation coefficients were calculated between the Callaway Nuclear Power Plant (Callaway) and nearby off-site weather stations. The complexity of these correlations depends on factors such as physical proximity, geographic features, and topology, potentially necessitating multivariate analysis (MVA). Furthermore, …

Transport And Plugging Behavior Of Co2-Resistant Preformed Particle Gels In High Conductive Channels For Conformance Control, Adel Alotibi

Doctoral Dissertations

"Improving oil recovery is essential with rising global oil demand and declining production in mature fields. CO₂ flooding has been widely applied as a major Enhanced Oil Recovery (EOR) method due to its effectiveness in boosting oil recovery while enabling safe carbon storage in the subsurface. However, in fractured and highly heterogeneous reservoirs, CO₂ often flows through paths of least resistance, leading to early breakthrough or quick excessive CO₂ production and leaving substantial oil in unswept zones or areas. Traditional in-situ polymer gels have been applied to control CO₂ flooding conformance, their performance has been varied, …

Polybenzodiazine Aerogels: All-Nitrogen Analogues Of Polybenzoxazines - Synthesis, Characterization, And Their Application In Carbon Dioxide Capture, Vaibhav Edlabadkar

Doctoral Dissertations

"The rapidly risen concentration of carbon dioxide in the atmosphere over recent years contributed to global warming and ocean acidification. Carbon capture is viewed as an essential tool from keeping atmospheric CO₂ levels from rising further. This thesis focuses on the development of new materials for high capacity and selective adsorption of CO₂. One such material was based on a newly synthesized tetrahydroquinazoline (THQ), which was designed as an all-nitrogen analogue of main-stream benzoxazine monomers. THQ solutions in DMF gelled at 100 °C via HCl-catalyzed ring opening polymerization to polybenzodiazine (PBDAZ) wet gels, which were dried in …

Mitigating Frost Heave And Thaw Weakening In Roads Using Wicking Geotextile, Javad Galinmoghadam

Doctoral Dissertations

"Excess water is known to be the primary cause of soil and foundation problems. In cold regions, water-related problems are exacerbated by seasonal freezing and thawing cycles. Frost heave and thaw weakening is the leading cause of premature pavement failure and consume considerable budgets of the Department of Transportations in cold regions. The first step to designing mitigation measures is the ability to predict frost heave under different conditions. This study aims to introduce a new method for quantifying frost heave using a prediction model based on the state surface approach. This proposed model addressed many inconsistencies and limitations of …

Photoionization Of Spin-Polarized Rydberg Atoms Out Of A Continuous Wave Optical Dipole Trap, Kevin Lee Romans

Doctoral Dissertations

"Recent research has demonstrated the need for a fully differential experiment on the photoionization of ⁶Li Rydberg atoms in a continuous wave (cw) laser field, as this would provide a new path forward for studying never before accessible atom-light interactions. Rydberg atoms are back in the focus of intense research due to their peculiar properties, which make them interesting candidates for quantum optics and information applications. In this work, we study the ionization of such Rydberg atoms, due to their interaction with a trapping laser field, by utilizing a reaction microscope (ReMi) capable of measuring photoelectron momentum distributions with …

Quantum And Classical Phase Transitions In Disordered Systems, Gaurav Ramesh Khairnar

Doctoral Dissertations

This work examines the effects of quenched disorder on classical and quantum phase transitions. There are countless examples of phase transitions in nature. Here, we study phase transitions in condensed matter with the help of simple models that focus on the essential unifying features of the problems. We are particularly interested in investigating how the presence of disorder changes the behavior of the system in the vicinity of a phase transition.

Here, we discuss three closely related problems regarding phase transitions. First we consider the behavior of highly diluted magnets with varying dilution levels in order to explain the unusual …

Ceramic Dielectrics For High Temperature Capacitor Applications, Alan Daniel Devoe

Doctoral Dissertations

Technical progress in microelectronics is allowing operation in environments that were previously considered impossible. Building complete electronic circuits for applications above 450 degrees C, such as the planned NASA missions to Venus, require a variety of active and passive components, including multilayer ceramic capacitors (MLCC).

This study explores calcium zirconate CaZrO3 and magnesium oxide MgO based dielectric compositions for MLCC applications that are capable of operating at extreme temperatures between 450 degrees C and 600 degrees C. Both materials were characterized with respect to impurities, dopants, crystal structure and microstructural development. Dielectric properties were measured to determine permittivity, dissipation factor, …

Applying Human System Integration Principles To The Investigation, Design And Validation Of Interventions For Self-Escape In Underground Mines, Eugene Adubofour Gyawu

Doctoral Dissertations

This dissertation investigates the use of human systems integration (HSI) to develop technologies for miners’ self-escape during a mine emergency, addressing barriers that compromise miner safety during emergencies.

Recognizing the inherently hazardous nature of underground mining, this study has three core objectives: (1) assessing miners' perceptions of proposed self-escape interventions, (2) designing interventions based on these insights, and (3) validating their effectiveness using experimental testing. This work evaluates self-escape interventions for both coal and metal/non-metal miners using scenario-based surveys, information design reviews, label designs and experimental testing methods varying across three distinct studies.

Results reveal that miners identified improvements to …

On The Importance Of Novel Adsorption Processes And Structured Adsorbents For Biogas Upgrading And Storage, Kyle Newport

Doctoral Dissertations

The current adsorption processes investigated for biogas upgrading encounter severe challenges with regards to both adsorbents and processes, which necessitate the design and development of novel approaches to effectively separate carbon dioxide from methane and, hence, produce pipeline-grade renewable natural gas (RNG) as a fuel. These key challenges include (i) moderate CO2/CH4 selectivity, (ii) relatively long cycle times, (iii) high regeneration energy requirements, (iv) high-pressure drop, and (v) short adsorbent lifetime. The current biogas upgrading processes typically rely on pressure swing adsorption (PSA) or temperature swing adsorption (TSA). While PSA cycles are fast, the system requires large amounts of energy …

Evaluating And Relaxing The Limits On Flexural Reinforcement Ratio Of Masonry Shear Walls, Tousif Mahmood

Doctoral Dissertations

Reinforced masonry shear walls (RMSWs), essential for lateral and out-of-plane load-resisting systems in modern construction are constrained by TMS 402/602 code limits on reinforcement ratios ("ρ" _"max" ) and axial compressive stresses (≤10% of masonry compressive strength, f_m^'), undermining masonry’s inherent compression capacity under high axial loads. This dissertation investigates the seismic performance of reinforced masonry shear walls (RMSWs) subjected to high axial compressive stresses (10–20% of f_m^'), with a focus on walls violating the maximum reinforcement ratio ("ρ" _"max") and axial load limits of TMS 402-22. Through experimental testing of 30 large-scale fully grouted (FG) and partially grouted (PG) …

Development Of Dual-Scan Nuclear Magnetic Resonance (Nmr) Pulse Programs For Spin-Lattice Relaxation Measurements, Zachary Mayes

Doctoral Dissertations

This research develops and refines the Split Inversion Pulse and Recovery (SIP R) methodology for spin-lattice relaxation (T₁) measurements in NMR spectroscopy. SIP R introduces a two-scan difference technique using a split inversion pulse sequence, where the 180° pulse is split into two 90° pulses phase-shifted with respect to each other. This approach simplifies data fitting, requiring only two parameters to extract T₁ values, compared to the traditional inversion-recovery method, which needs three. The SIP-R-DS and SIP-R-S adaptations extend this framework by incorporating selective NMR resonance excitations, enhancing its applicability to cross-polarization experiments and enabling unobstructed NOE measurements. These adaptations …

Systematic Esd Analysis And Modeling For Electronic Device, Zhekun Peng

Doctoral Dissertations

Systematic ESD analysis provides good pre-compliance to ESD robustness evaluation on the electronic device from device level to component/system level to on-chip level. The whole process involves corona discharge on display, system level ESD analysis on PCB for race condition and transient response and 3D IC package impact to on-die ESD.

ESD to the display cover glass can damage touchscreen traces by sparkless corona discharges on the glass surface. A non-linear time dependent transmission-line model is proposed to model corona streamer propagation in terms of the coupling current and propagation speed. Results are highly promising to model the corona discharge …

The Real-Time Detection Infrastructure Of Ligo, Virgo, And Kagra: Data Products, Current Performance, And Future Developments, Sushant Sharma Chaudhary

Doctoral Dissertations

The discovery of the binary neutron star merger event GW170817 marked the dawn of Multi-Messenger Astronomy (MMA) with Gravitational Waves (GWs). Such multi-messenger events are of immense scientific interest due to the wealth of information they provide through joint observations across different messengers. In this rapidly evolving field, prompt identification and timely distribution of alerts is critical for follow-up observations.

This work offers a comprehensive overview of the LIGO-Virgo-KAGRA (LVK) Collaboration’s low-latency analysis pipeline for GW events, covering key stages from calibration and data analysis to the issuance of public alerts. I examine the latency and accuracy of each stage …

Mid-Field Shock And Impulse Estimation Methods For Blast Loading On Tall Targets, Ethan Allan Steward

Doctoral Dissertations

Blast resistant structural design continues to be a major research area for governments around the world due to explosive threats from both state and non-state actors. Many of the typical targets of explosive attacks, such as government buildings, commercial high rise office buildings, and apartment complexes are mid to high-occupancy buildings that present a tall profile relative to the charge size and are often clad in curtain walls. In blast resistant structural design, the origin of a shock wave is typically assumed to be in the far-field, creating a wave that is nearly planar and parallel to at least one …

Measurement Method And Applications Of Transfer Function In Rf Desensitization Problem, Xiangrui Su

Doctoral Dissertations

Radio frequency (RF) desensitization issues comprise two components: noise radiation sources and the transfer function from noise sources to the victim antenna. RFI is a critical challenge in modern electronic systems, particularly in densely packed environments. This work presents a comprehensive study of RFI, addressing key aspects through three novel contributions. First, a transfer function measurement method is developed for compact metallic enclosures. This method provides a precise characterization of the electromagnetic (EM) environment within confined spaces, enabling accurate identification of interference pathways. Second, an EM emission management analysis framework is proposed, leveraging transfer functions to quantify and mitigate interference …

Assessing And Comparing Geophysical Methods For Resolving Shallow Subsurface Geology, Abdullah Basaloom

Doctoral Dissertations

Geophysical methods are essential tools for investigating shallow subsurface structures, offering non-invasive means to characterize geological features and detect anomalies. Techniques such as electrical resistivity tomography (ERT), towed Transient Electromagnetic (tTEM), seismic refraction, magnetic, gravity, and magnetotelluric (MT) are commonly employed to image subsurface conditions with high resolution.

This study started with an in-depth analysis of comparing results co-located in space to assess uncertainties and resolution in the obtained resistivity models in the Kansas River Alluvial Aquifer (KRAA). Our results provided a quantitative interpretation of resistivity estimates between different geo-electrical methods (ERT, tTEM and DPEC). Following this, we provided a …

Novel Nano-Formulations Based On Flash Nanoprecipitation For Ocular Drug Delivery, Lin Qi

Doctoral Dissertations

Effective ocular drug delivery has always been a challenge for clinical and research. Although many nanotechnology-based formulations have been developed and showed great potential in ocular drug delivery, this is far from enough to meet clinical requirements. These studies aimed at the design and synthesis of novel nanoparticles using multi-inlet vortex mixer (MIVM) to improve ocular drug delivery efficiency. The first project involves packaging two different anti-glaucoma drugs, brimonidine (BM) and betaxolol (BX), into solid drug nanoparticles (SDNs) by MIVM, which can achieve both functions, reducing aqueous humor production and promoting aqueous humor efflux. The studies demonstrate that the SDNs …

Optical Detection Of Instantaneous Microwave Frequency And Displacement, Behzad Boroomandisorkhabi

Doctoral Dissertations

Research presented in this research is focused on developing and implementing novel photonic systems for instantaneous microwave frequency and displacement measurement, emphasizing cost-effectiveness, scalability, and high resolution. The research is encapsulated in three core studies: the design of all-fiber ultrafast ranging Lidar for medical motion management, the application of dispersive interferometry using picosecond laser pulses for laser ranging, and the integration of microwave photonic systems with digital signal processing (DSP) for enhanced measurement precision.

The work achieves micrometer-scale displacement accuracy and microwave frequency resolutions within ±1 MHz across wide dynamic ranges by leveraging dispersive interferometry and time-stretch techniques. The studies …

Design And Synthesis Of Organocatalyts For Efficient Decontamination Of Organophosphate-Based Nerve Agents And Pesticides, Emmanuel Kingsley Darkwah

Doctoral Dissertations

Exposure to organophosphate-based nerve agents and pesticides poses significant health and security threats to civilians, soldiers, and first responders. Despite extensive efforts to develop chemical detoxification agents for use in topical applications on exposed skin surfaces and for intravenous injections, there remains an unmet need for effective, non-hazardous decontaminating agents. The current state-of-the-art decontaminating agent, Dekon-139 (2,3-butanedione oxime, potassium salt), exhibits adverse effects when applied to the skin.

In this study, we designed and synthesized pharmaceutically relevant aminoguanidine-derived aldimines that are relatively non-toxic and substantially more effective at decontaminating nerve agents and pesticides compared to existing agents, and they act …

Higher-Order Statistics And Normalized Decay Analysis For Detector Deadtime Characterization, Abdallah Wazzan

Doctoral Dissertations

Detector deadtime limits radiation measurement accuracy at high count rates, yet current methods rely on idealized paralyzable or non-paralyzable models. Real detectors exhibit hybrid behavior requiring advanced characterization approaches. This study explores deadtime characterization using two Monte Carlo simulation approaches: higher-order statistical analysis of inter-arrival times and simplified deadtime correction with hybrid models.

Using MATLAB (PULSE-WIZ), we analyzed full decay curves spanning ~4.5 half-lives of Cobalt-60 and Vanadium-52, examining coefficient of variation (CV), skewness, and kurtosis of inter-arrival times, plus normalized decay curves with Full Width at Half Maximum (FWHM) analysis. Hybrid models incorporated paralyzable and non-paralyzable components with dead …

Advancing Thermodynamic Modeling In Materials Design: From Phase Stability In Metallic Systems To Ferroelectric Property Prediction In Functional Oxide, Kyaw Hla Saing Chak

Doctoral Dissertations

This dissertation advances the CALPHAD (CALculation of PHase Diagrams) approach for thermodynamic modeling which often lacks sufficient description of crystal lattices for critical phases in multicomponent system. Additionally, CALPHAD does not consider the structural features and its connection with functional properties for functional materials. To address these issues, a novel dual-ordered sublattice model for the κ-phase in Fe-Al-C system, (Fe,Al)3(Fe,Al)1(C,Va)1(C,Va)3, is introduced that improves predictions of equilibrium compositions and phase stability by accounting for both substitutional and interstitial ordering. For the Fe-B-C system, new sublattice formulations for FCC [(Fe)1(C,B,Va)1] and BCC [(Fe,B)1(C,B,Va)3], phases enhance boron solubility predictions and reveal insights …

Introducing Triangular Groups And Further Results On Magic Groups, Nicholas Charles Fleece

Doctoral Dissertations

In this research, we discuss two new topics in group theory. First, we define an n-magic square in a group to be a nxn array of group elements whose rows, columns, and diagonals have the same product. This definition is akin to the idea of magic squares in the integers. Groups that have an n-magic square are said to be n-magic. We begin with some preliminary results and focus much of our attention on 3-magic groups, though we also give some results for higher n. Through a series of propositions, we ultimately prove a characterization theorem for 3-magic finitely generated …

Supporting Human-Ai Interaction From User Expectations To Mental Models, Harishankar Vasudevanallur Subramanian

Doctoral Dissertations

Explainable AI (XAI) aims to unravel the "black box" nature of AI systems and provide insights into the inner workings that lead to a prediction. However, the best XAI communication varies depending on the individual, task, and broader context. It is challenging to anticipate the best XAI for a particular use case. One strategy is for users to build an appropriate mental model of AI with both prediction and system level XAI. To date, little research has focused on quantitatively measuring users interacting with system-level XAI. This dissertation has three primary contributions. The first contribution is a scoping review paper …

Dynamic Response, Assessment, And Retrofitting Of Prestressed Concrete Bridge Girders Subjected To Lateral Impact Loads, Haitham A. Abdelmalek

Doctoral Dissertations

Over height vehicle collisions pose a growing threat to the resilience of bridge infrastructure across the United States. According to the American Road & Transportation Builders Association (ARTBA, 2024), approximately 36% of all U.S. bridges require major repair or replacement, with an estimated cost of $400 billion. This dissertation investigates the structural dynamic response, damage assessment, and retrofitting strategies for prestressed concrete (PC) bridge girders subjected to lateral impact loading.

The research comprised two main phases: (1) numerical modeling and (2) experimental testing. A validated 3D nonlinear finite element (FE) model was developed to conduct parametric studies on impact behavior, …

Optical Sensor Instrumentation For Enhanced Continuous Caster Development, Hanok Wondimagegnehu Tekle

Doctoral Dissertations

Fiber-optic sensors are an emerging technology that can enhance process monitoring and control in steelmaking. They are especially valuable in the continuous caster’s harsh environment. This dissertation presents the industrial application and demonstration of three sensor types: single-mode silica fiber with Rayleigh-based Optical Frequency Domain Reflectometry (OFDR), sapphire fiber (single-crystal alumina) with Fiber Bragg Gratings (sFBG), and an in-line Raman spectroscopy probe. Each sensor served a distinct role in the continuous caster. Rayleigh OFDR sensors were embedded in tundishes for distributed thermal mapping at 7-mm spatial resolution across ≈4 m. Measurements were taken during preheating, casting, and ladle exchanges, and …

Synthesis Of Graphene Using Carbonaceous Materials In An Ultrasonic Reactor, Paul Chukwuma Ani

Doctoral Dissertations

The synthesis of high-quality graphene from sustainable carbonaceous feedstocks offers an avenue to reduce the environmental and economic costs associated with conventional graphite-based production. This research investigates the co-utilization of biochar and graphite as precursors for graphene fabrication in an ultrasonic reactor. Biochar was produced from biomass via downdraft gasification at 850 °C, yielding a high fixed-carbon, partially graphitized material with favorable surface area and porosity. Graphite, selected for its crystalline structure, was investigated with biochar to assess the influence of precursor composition on exfoliation efficiency, layer thickness distribution, and defect density. Ultrasonic-assisted liquid-phase exfoliation was employed, with process parameters …