Digital Commons Network^™

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) …

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 …

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 …

The Structure, Properties And Dissolution Behaviors Of Phosphate Glasses, Han Zhang

Doctoral Dissertations

The poor chemical durability remains a critical challenge for the application of phosphate glasses. This study investigates the compositional influences on the structure, properties and chemical durability of Li2O-ZnO-P₂O₅ glasses. Their structural characteristics were analyzed utilizing high-performance liquid chromatography, Raman spectroscopy, and X-ray photoelectron spectroscopy. The incorporation of (Li2O+ZnO) in LZeq glasses depolymerizes the phosphate network. In LZ40P and LZ45P glasses, Li⁺ initially replaces Zn²⁺ associated with non-bridging oxygens (NBOs) in Q² tetrahedra. Once the substitution in Q² is complete, further Li⁺ incorporation leads to the replacement of Zn²⁺ in Q^{1 …}

Design Of Real-Time And Energy-Efficient Driver Assist Systems Using Electroencephalogram And Neuromorphic Computing, Nathan Alan Lutes

Doctoral Dissertations

Despite the technological breakthroughs in advanced driver assist systems, distracted driving persists as a major challenge to roadway safety. This investigation advances the body of knowledge towards a solution by developing an individualized driver-state detection method using electroencephalogram (EEG) and neuromorphic computing to provide a less invasive and more energy efficient ADAS solution. It furthermore explores the changes in brain functional connectivity under distracted conditions to better understand brain state information that could be used for neuro-feedback intervention systems. The first contribution introduces the concept of using Convolutional Spiking Neural Networks (CSNNs) for recognition of patterns with movement-intention predictive power …

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 …

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, …

Nutrient Fate, Mass Balance, Species Selection, And Plant Management Strategies With Floating Treatment Wetlands, Carla Campbell

Doctoral Dissertations

Excess nutrients in shallow urban ponds can lead to harmful algal blooms, low dissolved oxygen, and internal phosphorus cycling. These effects can compromise municipal water supplies and cause negative impacts on fisheries and recreation. Floating treatment wetlands (FTWs) show promise to mitigate surface water nutrient pollution. However, despite recent research, many aspects of FTWs remain poorly characterized. The contribution of FTW components to nutrient removal, local species selection, and plant management strategies were the focus of this dissertation. Mesocosm experiments revealed that the combination of plants and coir fiber growth media in FTWs appeared to positively affect plant biomass gain …

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 …

Deep Learning Architecture Design For Nano-Satellite Image Super-Resolution, William Everette Symolon

Doctoral Dissertations

Increasing threats to U.S. national security satellite constellations have resulted in an increased interest in constellation resilience and satellite redundancy. NanoSats have contributed to commercial, scientific and government applications in remote sensing, communications, navigation, and research. They also have the potential to enhance satellite constellation resilience. However, the inherent size, weight, and power limitations of NanoSats enforce constraints on imaging hardware; the small lenses and short focal lengths result in imagery with low spatial resolution, which limits the utility of CubeSat images for military planning purposes and national intelligence applications. This research proposed a deep learning architecture capable of enhancing …

Advancements In Signal Processing And Image Reconstruction For Active Microwave Thermographic Measurements, Logan Martin Wilcox

Doctoral Dissertations

Active microwave thermography, or AMT, is a coupled electromagnetic-thermographic nondestructive testing and evaluation technique. AMT has found success in a variety of inspection needs in the aerospace, space, and infrastructure fields due to its unique type of thermal excitation. During an AMT inspection, a specimen is exposed to microwave energy from a radiating source (i.e., an antenna). This exposure to microwave energy results in dielectric/magnetic heating, which causes an increase in temperature and potential defect indications to manifest on an inspection surface (which is measured via an infrared camera). Due to the use of an antenna, there is a spatially …

Investigating The Effects Of Fly Ash On The Properties Of Silica-Deficient High Alumina Materials, Sai Akshay Ponduru

Doctoral Dissertations

This research is made up of five studies mainly focused on attaining sustainability in high alumina cements like calcium aluminate cement (CAC) and calcium sulfoaluminate belite cements (CSAB) by partially replacing them with additives and supplementary cementitious materials (SCMs) like fly ash (FA). The first study focused on understanding the reaction kinetics of CAC and FA binders at different replacement levels (i.e. between 10%-to-50% by mass) and their effect on mechanical properties. It was also shown that the reactive nature of FAs can be determined by calculating a single parameter called number of constraints (nc) derived from topological constraint theory. …

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 …

Identification Of Corrosion Damage, Vibration, And Loose Conections In Aircraft Data Transmission Lines Using Reflected And Transmitted Signals; Formulation Of Vegetable Oil-Based Nanofluids As Cutting Fluids For Mql Machining, Saidanvardzhon Valiev

Doctoral Dissertations

This research presents a novel Frequency Domain Transmitometry (FDT) method that uses transmitted signals (S21) to detect and characterize aircraft data transmission lines (ADTL) corrosion damage without additional reflectometry circuitry. Corrosion experiments were conducted according to ASTM G85-A5 over 14 weeks. Combined FDT and reflected signals (S11) analyses revealed distinct three-peak signatures associated with damage and corrosion. The square root of the Area Under the Curve (AUC) of the FDT damage peak and the Full Width at Three-Quarter Maximum (FW3QM) of the S11 damage peak is correlated with corrosion propagation depth and width. S11 signals were further used for vibration …

Bibliometric And Visualisation Analysis Of Biomass Burning Research In Thailand (1997-2024), Weerachon Sawangproh, Arika Bridhikitti

Applied Environmental Research

Biomass burning is a major driver of air pollution and climate-related impacts in Thailand, but a national-level synthesis of research efforts is lacking. This study conducts a comprehensive bibliometric and qualitative review of 256 peer-reviewed publications from 1997–2024, using Scopus-indexeddata to explore research trends, thematic patterns, and existing gaps. The analysis reveals a strong emphasis on atmospheric chemistry, air quality modeling, and remote sensing, which collectively account for more than 60% of the research landscape.Studies frequently focus on pollutants such as PM2.5,PAHs, carbon monoxide, and heavy metals, with biomass burning identified as a dominant source, especiallyduring the dry season in …

Comparing The Sensitivity And Specificity Of Novel Motor Assessments For Traumatic Brain Injury, Paula K. Johnson, Ariana M. Hedges-Muncy, Erin D. Bigler, Lorie Richards, Steven Knight Charles

Faculty Publications

Background: Portable technology that records movements with high accuracy provides potential for sensitive clinical movement tests for individuals who experienced a traumatic brain injury (TBI). Objective: (1)To present impairments assessed using markerless motion capture (MMC) and (2) to compare the sensitivity and specificity of the MMCmediated tests to each other and to common clinical tests. Design: Screening study, using as criterion standard the ability to classify participant with TBI versus control participant. Setting: Research laboratory. Participants: The study included 30 individuals with TBI and 101 control participants. Entry criteria included most recent head injury < 5 years old, no history of movement issues prior to injury, no movement-affecting medications, and sufficient cognitive ability to follow instructions. Interventions: Not applicable. Main Outcome Measures: Performance on MMC-mediated tests and existing clinical analogs. MMC-mediated tests included finger oscillation, simple reaction time, and visually guided movement tasks. For comparison, participants also completed the following clinical tests: Halstead–Reitan finger tapping, simple reaction time test, and Beery Visuomotor Integration test. Impairments were identified as test scores of participants with TBI that fell outside of the 95% interval of control participants’ test scores. Random forest analysis was used to calculate the sensitivity and specificity of MMC and clinical tests according to their ability to correctly classify participants with TBI and control participants. Results: MMC-mediated tests revealed impairments in more participants with TBI than clinical tests in all three TBI groups (mild, repeated, and moderate to severe). Similarly, MMC-mediated tests revealed a higher percentage of scores as impairments than clinical tests in all three groups with TBI. Furthermore, MMC-mediated tests proved more sensitive and more specific than clinical tests (70% versus 50% and 98% versus 93%, respectively). Conclusion: MMC-mediated tests are sensitive and specific (compared to traditional clinical tests) and have potential to fill a gap in clinical care of TBI.

Actuator Disk Model For Aeropropulsive Coupling Effects In Vortex Particle Method, Eduardo Alvarez, Vineet Ahuja, Vinod Lakshminarayan, Aaron Perry, Ryan Anderson, Andrew Ning

Faculty Publications

Blown lift and distributed electric propulsion aircraft pose strong aeropropulsive coupling effects that cannot be ignored during the early stages of design. In this study, we develop an advanced actuator disk model (ADM) for aeropropulsive coupling effects of ducted fans with the vortex particle method (VPM). The advanced ADM consists of (1) an actuator disk at the rotor plane, (2) a surface vortex sheet modeling the mixing and convection of blade tip vorticity along walls, and (3) a powered wake at the exhaust. With these three components, a propulsion jet with an arbitrary velocity profile is formed and interactions with …

Origami Folding Pattern Development For Gossamer 18 Structures, Larry L. Howell, Ivy Running, Carolina Wright, Robert J. Lang, Spencer Magleby

Faculty Publications

Gossamer structures for satellites are large, thin deployable structures that are attractive for space applications because they can be stowed compactly for transportation and deployed to have large functional surface areas. Reflectarray antennas, in particular, are candidates for gossamer structures because they can be realized on thin membranes. However, the efficiency of reflectarray antennas decreases with any deviations from a flat plane, including those induced by plastically deformed creases. Rolling membranes can prevent some plastic deformation, but requires relative slipping between layers that are rolled together. In this work, we describe, analyze, and demonstrate two rolled configurations for deployable gossamer …

Mill Power Consumption And Fuel Particle Size Distribution While Co-Milling Bituminous Coal With Steam-Exploded Woody Biomass In A Conventional Bowl Mill, Brian Schoof, Rajarshi Roy, Regan Kuttler, Parker Latour, Scott Montgomery, Jacob Tuttle, Gwendolyn Bennett Bennett, Brian D. Iverson, Andrew Fry

Faculty Publications

The mill behavior of a 312 Combustion Engineering Raymond Bowl Mill was studied with five blends of Utah bituminous coal and steam-exploded woody biomass, ranging from 100 % coal to 100 % biomass. Mill power consumption increased with biomass content, peaking at 187 % of the power required for 100 % coal before the mill faulted at 100 % biomass. After repositioning the rollers, power consumption for 100 % biomass decreased by 13 % compared to 100 % coal. SEM images revealed that milled biomass particles were non-spherical, indicating some fibrous structure remained post steam-explosion. The particle size distribution (PSD) …

Drop Dynamics During Condensation On Superhydrophobic Surfaces In Vapor Shear Flow, Shaur Humayun, R. Daniel Maynes, Julie Crockett, Brian D. Iverson

Faculty Publications

Accurate models for predicting drop dynamics, such as maximum drop departure sizes, are crucial for estimating heat transfer rates during condensation on superhydrophobic (SH) surfaces. Previous studies have focused on examining the heat transfer rates for SH surfaces under the influence of gravity or vapor flowing over the surface. This study investigates the impact of surface solid fraction and texture scale on drop mobility in a condensing environment with a humid air flow. Experiments recorded condensation with varying surface feature sizes from micro- to nano scale under different flow rates. Video analysis detected the drop-size distribution and maximum drop departure …

Internally Stowed, Radially Deployed Radiator Panels For Passive Cubesat Thermal Control, Josh R. Cannon, Kyle N. Havey, Noah S. Housley, Rydge B. Mulford, Brian D. Iverson

Faculty Publications

CubeSats experience significant thermal loads due to solar irradiation and the dissipation from electrical components. The high heat dissipation per unit volume can lead to mission failure if not properly managed. Deployable radiators that are externally stowed and passively actuated in response to changes in CubeSat temperature have been explored as a viable solution. This work describes a radially deployed fin array that is stowed within the CubeSat body when the required heat dissipation is low and passively deploys when the required heat dissipation is high. Internal stowage improves thermal transport to the deployable fins and minimizes heat loss when …

Automated Infinite Combos Detection System For Collectible Card Game, Amornpong Trakarnkulphun

Chulalongkorn University Theses and Dissertations (Chula ETD)

In Collectible Card Games, resources management is one of the most effective strategy. However, there are some combinations of cards which produce unlimited resources called infinite combos. Too-cheap infinite combos that can be played early in the game break game environment, because the player who executes the combo immediately wins. To solve the problem, game designers usually restrict a part of the combos from being played. Due to the large number of cards in the card pool, it is difficult to search for these combos and solve this problem before a release date of a card set. This research aims …

Effect Of Solvent On Nonanoic And Azelaic Acids Yield Enhancement From Oxidative Cleavage Of Oleic Acid, Chakreeya Santhadklang

Chulalongkorn University Theses and Dissertations (Chula ETD)

This study investigates the effect of solvent choice on the oxidative cleavage of oleic acid using hydrogen peroxide (H2O2) as the oxidant, with a focus on improving the yields of nonanoic acid (NA) and azelaic acid (AA). Solvent selection was found to play a critical role due to polarity differences between the reactants and oxidants. tert-Butanol was unsuitable because of its low boiling point, leading to the evaluation of higher-boiling solvents including guaiacol, acetoin, ethyl lactate, and isobutyric acid. Guaiacol and acetoin exhibited undesirable chemical reactivity, while ethyl lactate resulted in low yields due to hydrogen bonding with intermediate species. …

Experimental Investigation Of Surfactant Impact On Surfactant-Oil-Brine System For Surfactant Enhanced Oil Recovery, Chananpat Worpattanaluk

Chulalongkorn University Theses and Dissertations (Chula ETD)

Enhanced Oil Recovery (EOR) is a vital technique for improving hydrocarbon extraction efficiency from mature or low-production reservoirs. Among various EOR methods, chemical flooding, particularly surfactant-based EOR, has gained attention due to its ability to reduce interfacial tension (IFT), to alter rock wettability, and to mobilize trapped oil. However, the performance of surfactant systems is highly sensitive to reservoir salinity, temperature, and rock-fluid interactions, leading to surfactant precipitation, adsorption losses, and interfacial tension reduction. Therefore, understanding the effects of salinity, surfactant concentration, and the role of scale inhibitors on the physicochemical stability of surfactant-oil-brine systems is essential for designing robust …

Enhancing Performance Of Lstm For Water Level Forecasting In Lower Mekong River With Feature Selection Strategy, Chanreng Sey Nhim

Chulalongkorn University Theses and Dissertations (Chula ETD)

This study addresses key research gaps, including the lack of systematic feature selection, structured hyperparameter optimization, and comprehensive long-term and cross-location performance evaluation in the Lower Mekong River Basin to enhance the water level forecasting performance. The research has utilized a Vanilla Long Short-Term Memory (LSTM) network trained on 22 years of historical water level data from the Mekong River Commission (MRC) and 16 localization meteorological features from Open-Meteo. The methodology uses Grid Search optimization for hyperparameter tuning and employs the Spearman rank correlation coefficient as a filter feature selection technique to identify relevant input variables and minimize redundancy. Performance …

Efficient Photocatalytic Hydrogen Evolution Via Novel Syntheses Of Srtio₃/G-C₃N₄ Heterojunction Photocatalysts, Chiramet Thatsanakunlaphan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Strontium titanate/graphitic carbon nitride (SrTiO3/g-C3N4) heterojunctions are widely used as photocatalysts. However, traditional multistep synthesis methods for these photocatalysts often involve complexity, long processing times, and high energy consumption. To address these issues, a systematic comparison of various simplified synthesis approaches was conducted, emphasizing the influence of synthesis parameters on the structural properties and hydrogen evolution performance. Six comparative studies were conducted to illustrate the roles of solvent choice, thermal post-treatment, and synthesis route. Results showed that ethylene glycol consistently produced more active photocatalysts than ethanol in both one-pot and two-step solvothermal methods. Non-calcined samples exhibited superior hydrogen evolution activity …

Quality Of Life Prediction For Driving Route Planning System Using Image Recognition And Deep Learning, Intouch Prakaisak

Chulalongkorn University Theses and Dissertations (Chula ETD)

Assessing travel-related Quality of Life (QoL) is a significant challenge due to its reliance on subjective human perception, which is difficult to measure. Traditional studies are often constrained by the limited scope of costly, manual data collection. The significant contribution of this research is the introduction of a new framework that can analyze tourist perception on a large and systematic scale. The novelty of this work lies in the utilization of Google Street View (GSV) as a large-scale visual data source, coupled with the use of a sequence-based model to analyze travel routes, which allows for the simulation of the …

Improving The Availability Of Aluminium Sheath Extrusion Machines In The Cable Industry, Jirathana Vasinyont

Chulalongkorn University Theses and Dissertations (Chula ETD)

Aluminium sheath extrusion machines (AL Seamless) play a critical role in the production of high-voltage cables, ensuring the integrity and quality of electrical transmission infrastructure. However, after commissioning such machines at PD Company was fraught with challenges, including frequent breakdowns, limited machine availability, and production inefficiencies. The underlying issues stemmed from inadequate standard operating procedures (SOPs), insufficient knowledge transfer during commissioning, and suboptimal maintenance practices. To address these challenges, this research applied structured methodologies, including Failure Mode and Effects Analysis (FMEA) to identify critical failure points and root causes, and Total Productive Maintenance (TPM) to improve operational reliability. Knowledge transfer …

Out-Of-Domain Tuberculosis Detection From Chest X-Ray Images Using Meta Learning With Soft Labels, Kanokphat Jinanarong

Chulalongkorn University Theses and Dissertations (Chula ETD)

Automated tuberculosis screening from chest x-ray images could greatly benefit regions with limited medical resources. However, currently available methods could not handle this problem well due to the difference in chest x-ray images in each region caused by the difference in machine and demographics, the possible noise in the available labels, and other reasons. We therefore propose a new machine learning algorithm that could detect tuberculosis with great accuracy on any other data sources by learning from completely different data sources. We used a model-agnostic meta-learning together with a soft label approach, utilizing the meta-gradient to dynamically adjust the soft …

A Study On The Impact Of Superconducting Fault Current Limiteron Arc Flash Hazard In An Industrial System, Kittipong Anantanasap

Chulalongkorn University Theses and Dissertations (Chula ETD)

The increasing integration of distributed generation raises short-circuit current levels, which lead to concerns about equipment overheating, insulation deterioration, and system stability issues. The Resistive Superconducting Fault Current Limiter (R-SCFCL) offers an effective solution by dynamically increasing circuit impedance during faults without affecting normal operation. However, its integration may alter the fault-clearing time of the protection system, which is crucial for arc-flash safety. This study evaluates the impact of R-SCFCL integration on arc-flash hazards in an industrial power system, utilizing DIgSILENT PowerFactory and calculations based on IEEE 1584. Results indicate that while the R-SCFCL effectively reduces arcing current, the incident …