Digital Commons Network^™

Toward Vehicle-Agnostic Driving Signatures For Cognitive Impairment Prediction From Naturalistic Driving Data, Aadarsha Gopala Reddy

McKelvey School of Engineering Graduate Student Theses & Dissertations

This thesis studies whether naturalistic driving data can help predict binary Clinical Dementia Rating (CDR) status while accounting for differences across vehicles. The final analytic dataset comprised 26,968 participant-weeks from 304 participants. Weekly driving features were derived from real-world telematics data and combined with four demographic covariates. Primary model comparisons used leave-one-participant-out (LOGO) cross-validation, with one individual held out at a time and pooled participant-level metrics used as the main reporting surface.

The main comparison includes six model families evaluated on the same dataset under a shared LOGO framework. Performance remained modest overall. GRU-DANN had the highest participant-level ROC AUC …

Largest 2-Regular Subgraphs In Complete S-Partite Graphs, Yiyang Jiang

McKelvey School of Engineering Graduate Student Theses & Dissertations

In this thesis, we focus on the class of complete $S$-partite graphs, for $S$ an undirected graph possibly with self-loops, and address the problem of finding largest $2$-regular subgraphs of these graphs, which can be formulated as an integer linear program. Roughly speaking, a complete $S$-partite graph is obtained by replacing every single node of $S$ with a number of nodes, preserving the edge/non-edge relations of $S$. Our motivation in studying largest $2$-regular subgraphs is rooted in the structural systems theory, particularly in the problem of finding largest subnetworks that can sustain controllability or asymptotic stability of the corresponding subsystems. …

Improving Semantic Precision In Text-To-Image Diffusion Models Via Latent-Space Optimization And Semantically-Parsed Evaluation, Mohammad Rouie Miab

McKelvey School of Engineering Graduate Student Theses & Dissertations

Text-to-image diffusion models can produce visually impressive images from natural-language prompts, but they often fail to satisfy the detailed semantic constraints expressed in compositional prompts. Typical failure modes include omitted objects, merged entities, incorrect quantities, incorrect attribute binding, and leakage of one entity's attributes onto another. This thesis studies the problem of semantic precision in text-to-image generation: how faithfully a generated image satisfies the structured meaning of its prompt.   The thesis makes two linked contributions. First, it presents a training-free inference-time refinement method for diffusion-based image generation. The method operates directly in latent space during denoising and uses noun-phrase-aware cross-attention …

Does Your Sleep Really Matter?, Kristy Riddle

Student Scholar Symposium Abstracts and Posters

In this project, I am tracking 10 of my daily statistics revolving around my routine. I am using an Oura Ring to help accomplish some of the statistics. These include: readiness score, sleep score, screen time on cell phone, time spent on social media, steps taken, stress levels, restorative time, pages read, homework time spent, and oz of water consumed. I will be utilizing Excel for my data and will have around 3 months worth of statistics. hope to learn more about my levels of efficient sleep and how I can better improve my motivation as a student. This project …

Interpreting American Sign Language: A Literature Review Of Assistive Technologies, Natalie Louise Paradiso, Emma Grace Kochenderfer

Student Scholar Symposium Abstracts and Posters

American Sign Language (ASL) is a visually elaborate, spatially oriented linguistic methodology that relies on combinations of hand movements, body positioning, facial expressions, and motion/spatial perception, aspects of which make interpretation difficult for automated machine recognition. Current assistive technology approaches to ASL interpretation are generally within the categories of computer vision models (including deep learning, multi-focus image fusion, and keypoint tracking) and wearable, multimodal/sensor-based approaches (such as smart glasses and inertial-sensor gloves). Within controlled environments, computer vision models perform well. However, when applied to conditions such as non-manual signs/features, signer variability, and rapid assimilation, they falter in processing all aspects …

Freshman 15? Freshman 50?? The Reality Of Daily Life Habits Of A First Year College Student, Gregorio R. Salgado

Student Scholar Symposium Abstracts and Posters

This project presents a personal data tracking study in which I collected daily self-reported metrics over the course of the Spring semester using Excel. The variables tracked include sleep duration, caloric intake, screen time, social media usage, phone checks per day, family communication, and personal spending. The goal of this project is to identify meaningful patterns and correlations between daily habits and personal well-being.

Data was collected through a combination of manual logging and smartphone-generated daily reports. This study explores potential relationships between variables such as sleep duration and social media usage, as well as the association between family communication …

Developing Narrative-Based Stem Learning Tool For K-6 Visually Impaired Students, Daniel Tsivkovski, Dylan Ravel, Jeffrey Kraskouskas, Brandon Foley, Maryam Etezad, Franceli Cibrian, Rajeev Joshi, Ariel Han

Student Scholar Symposium Abstracts and Posters

This research develops a free, accessible web application that enables K-6 students who are blind or visually impaired (BVI) to learn STEM concepts using refreshable braille displays. Currently, most online learning tools are not designed for BVI students, creating a significant educational barrier.

The application interfaces with commercial braille displays and uses narrative-based learning to make STEM content approachable and engaging. By presenting material as personalized interactive stories generated with the help of Artificial Intellligence (AI), students can connect with concepts while developing braille reading skills. The curriculum design prioritizes accessibility through the Accessible Rich Internet Applications (ARIA) standards and …

Kl Dra As A Benchmark Laboratory For Accretion-Disk Physics: Constraints From Tess And Ground-Based Surveys, Luis E. Salazar Manzano, Liliana E. Rivera Sandoval, Jean-Marie Hameury, Craig O. Heinke, Iwona Kotko, Thomas J. Maccarone, Manuel Pichardo Marcano

Physics & Astronomy Faculty Publications

We present the longest-term optical analysis of the AM CVn system KL Dra using ∼11 yr of monitoring from TESS and wide-field ground-based surveys. The continuous TESS coverage allows us to characterise its frequent outbursts with unprecedented detail, providing the first comprehensive study of an AM CVn during outbursts and enabling detailed modelling of these systems. The superoutbursts in KL Dra generally include a precursor and are followed by a series of rebrightenings after which a sequence of 3–4 large amplitude normal outbursts is observed. We fit parametric profiles to each superoutburst component (precursor, rise to plateau, plateau, and decay), …

Coal Ash-Derived Aluminosilicate Precursors: A Chemical Engineering Approach To Geopolymer Characterization, Hafiz Abdul Basit, Abdullah Bashir, Abdur Raafey

World of Coal Ash Proceedings

The chemical and microstructural evaluation of coal-derived aluminosilicate precursors is critical for understanding their suitability in advanced construction material systems. In this study, a characterization of Class F fly ash, ground granulated blast furnace slag (GGBFS), and Silica Fumes (SF) was conducted to elucidate their morphological and elemental features. Scanning Electron Microscopy (SEM) was used to assess particle morphology and surface characteristics (porosity, particle diameter, particle geometry), and Energy-Dispersive X-ray Spectroscopy (EDS) to determine elemental composition and distribution. The analysis revealed distinct morphological and compositional differences among the precursors, including spherical fly ash particles, calcium-rich slag phases, and ultra-fine silica …

State Permitting Program Update, Jessica Reiss

World of Coal Ash Proceedings

State Permitting Program Update Jessica L. Reiss, Barnes & Thornburg LLP, 11 South Meridian Street, Indianapolis, IN 46204 KEYWORDS: states, permitting, permit program, rulemaking ABSTRACT At the end of 2016, the United States Congress authorized states to establish permit programs for coal combustion residuals (CCR) surface impoundments and landfills.[1] Since then, several states have established such programs, and the United States Environmental Protection Agency (U.S. EPA) has approved programs for Oklahoma,[2] Georgia,[3] Texas,[4] and North Dakota,[5] proposed approval for Wyoming,[6] and denied approval for Alabama.[7] Other states, such as Indiana,[8] are actively working through the state rulemaking process and plan …

Zero-Waste And High-Value Valorization Of Coal Combustion Residues Via Critical Minerals Recovery And Cementitious Materials Production, Hongyan Ma

World of Coal Ash Proceedings

Coal combustion residues (CCRs) pose significant environmental and disposal challenges, yet they also represent an untapped resource rich in aluminosilicates and critical minerals. This work presents a zero-waste, high-value valorization pathway that integrates critical mineral recovery with the production of cementitious materials. Advanced separation and extraction techniques are employed to recover strategically important elements such as gallium and rare earths, while the mineral-rich residues are simultaneously processed into supplementary cementitious materials (SCMs) for blended cements and concretes. This integrated approach not only offsets the environmental burden of CCR disposal but also supports domestic supply chains of critical minerals and reduces …

Revolutionizing Closure Systems: The Performance Advantages Of Structured Geomembranes, Scott Perugia

World of Coal Ash Proceedings

Coal combustion residual (CCR) containment facilities have traditionally been closed using methods that have changed little over several decades, but structured geomembranes are now reshaping closure design by improving slope stability, increasing interface friction, enhancing drainage, and providing long-term durability. Two systems are emerging as leading solutions: a structured geomembrane paired with a geotextile and vegetative cover, and a structured geomembrane paired with engineered turf. This presentation compares these approaches using field performance data, laboratory testing, and lessons learned, with emphasis on key factors such as infiltration control, drainage efficiency, slope stability, constructability, and regulatory compliance. The engineered turf system …

Developing Concentrated Brines / Salt Slurries For Disposal Of Coal Ash Wastewaters., Lance Edling

World of Coal Ash Proceedings

If coal ash wastewater is not fully concentrated to the greatest extent possible, then this results in greater disposal volumes and costs. However, concentrating a wastewater stream high in scaling compounds can be difficult. Membranes are prone to scale and Vacom thermal systems are higher in operating cost. This presentation will discuss the need to minimize disposal volumes by concentrating wastewater that is readily prone to scale and foul. The discussion will present past project examples of waste streams that were concentrated until salt crystals formed and the method used to minimize fouling and scaling during the concentration process. In …

Recinis™ Wet Beneficiation Process For Landfilled Coal Ash, Tim Sambrook

World of Coal Ash Proceedings

The decline of coal-fired power generation has reduced fresh “Run-of-Station” ash availability, increasing reliance on reclaimed ash from landfills to meet supplementary cementitious material (SCM) demand. This shift has lowered OPC replacement rates and raised concrete costs due to inconsistent ash quality. ReCinis™ offers a low-capex wet beneficiation solution for landfill-aged, saturated, and variable-quality coal ash. With over 5 billion tons of ash impounded in the U.S., this process enables long-term supply security where dry beneficiation is unsuitable. Combining proven mineral processing techniques with coal ash expertise, ReCinis™ can be deployed as a 150,000 tpa skid-mounted plant or scaled to …

Lessons Learned From A Full-Scale Discrete In-Situ Stabilization Project For Ccr Impoundment Closure, Tony Moran, Paul Jennings, Jacob Susser, Tim Silar

World of Coal Ash Proceedings

ENTACT, in collaboration with Silar Services, Inc., the patent holder of Discrete In-Situ Solidification (DISS) technology, has successfully performed a full-scale implementation of DISS in a Coal Combustion Residual (CCR) impoundment. DISS hydraulically isolates ash from surrounding groundwater by constructing a low-permeability barrier at the impoundment bottom to treat a layer of ash and tying into underlying natural soil layers. DISS enables targeted stabilization within a designated treatment zone, minimizing the disturbance of overburden compared to traditional excavation methods and reducing the use of costly cementitious reagents. The process starts with Reagentless Drilling of the overburden CCR utilizing a specialized …

From Clogs To Compliance: Overcoming Persistent Leachate Head Issues In Ccr Landfills, Breanne Kahnk, Zachary Bauman

World of Coal Ash Proceedings

State and federal regulations require that landfills, including coal combustion residual (CCR) landfills, be designed and operated to maintain leachate head levels of less than 30 centimeters (approximately 1 foot). While proper leachate collection system design and routine maintenance are critical for meeting this requirement, challenges such as clogging of drainage media, pipes, fittings and/or pipeline perforations, settlement of collection pipes, and breaks in the piping system can lead to elevated leachate levels, posing risks to compliance and long-term system performance. TRC will provide an overview of leachate collection system regulatory requirements along with design, operation, and maintenance strategies that …

Plasma Coal Ash Processing For Enhanced Recovery Of Rare Earth Elements & Precious Metals: Proven From R&D To Commercial Plants, George Paskalov, Victoria Campbell, Jason Honigberg

World of Coal Ash Proceedings

Our Radio-frequency Plasma System is an ash pretreatment before the application of extractive metallurgy and addresses current elemental, methodological, and technological limitations of complex and refractory coal ash. Our system data shows from 10-20% improved recovery, to 9x-100x. RFP can access all metals contained in coal ash. Our focus is not on the alteration of established methodologies, such as cyanidation for non-refractory ore, which has a proven return and capacity to achieve target revenue at-scale. Using the RFP systems, no waste is created, overburden can be more easily dealt with, and no metal content will be left behind. We assert …

Probing The Critical Element Chemistry Of Coal-Combustion Fly Ash: Electron Microbeam Investigations Of The Spent Ash From The Pilot-Scale Acid Extraction Of Rare Earth Elements From A Beneficiated Kentucky Fly Ash, James Hower

World of Coal Ash Proceedings

Fly ash derived from the combustion of an eastern Kentucky high volatile bituminous coal blend was beneficiated to yield a <75-μm product with a reduction in the carbon and spinels and reacted with a strong acid in a pilot-scale unit to extract rare earth elements. Electron microscopy showed a wide range of rare earth-bearing minerals. The acid-extracted fly ash had a rim that was depleted in REE and in most other elements except silicon.

Standardization Of Coal Ash Testing, Classification, And Harvesting, Benjamin Gallagher, Chris Frishcosy, Eric Hageman

World of Coal Ash Proceedings

Standards such as product specifications, test methods, practices and guides play a crucial role in supporting both commerce and science. Standardization helps build consistency and reliability whether it pertains to the performance of an ingredient in a product or in the measurement of a material characteristic. Coal combustion products, such as coal ash and synthetic gypsum, exhibit unique characteristics and many standard have been developed to characterize these materials and support their beneficial use. ASTM is a voluntary, consensus-based organization, and publishes many standards related to coal combustion products. Currently, there are seven ASTM standards related to chemical analysis of …

Leachate Quantification And Reduction – One Facility’S Path To Zld, Cedric Ruhl

World of Coal Ash Proceedings

The Environmental Protection Agency (EPA) promulgated Effluent Limitation Guidelines (ELG) that govern liquids discharged from energy production facilities. According to the ELG, energy production facilities that burn coal beyond December 31, 2034 must convert to a Zero Liquid Discharge (ZLD) system by December 31, 2029*. This presentation focuses on one coal-burning facility’s strategy to meet ZLD requirements. The predominant source of liquid that will be treated by the proposed ZLD system is leachate from an active coal combustion residual (CCR) landfill. Is the ZLD’s design capacity suitable for average leachate flow conditions? Is there enough leachate storage volume to manage …

Ai-Guided Upcycling Of Coal Combustion Residues In Blended Cement And Concrete, Hongyan Ma

World of Coal Ash Proceedings

Coal combustion residues (CCRs), including fly ash, bottom ash, desulfurization gypsum, etc., on specification or off-specification, remain an abundant yet underutilized byproduct of power generation. While these materials have long been considered as supplementary cementitious materials (SCMs), their variable chemical and physical characteristics limit broader adoption in blended cement and concrete. This study introduces an AI-guided framework to accelerate the upcycling of CCRs into high-performance construction materials. By integrating materials informatics, machine learning models, and experimental validation, the framework enables rapid property prediction and performance-based preprocessing recommendation or mix design optimization for diverse CCR sources. Preliminary results demonstrate the ability …

Comparison Of Residuals From Neighboring Power Stations With Different Coal Combustion Technologies, Allan Kolker, Denise Levitan, Brett Valentine

World of Coal Ash Proceedings

Due to the ongoing need for critical minerals, coal combustion residuals (CCR), like fly ash, have been evaluated as a potential source of critical minerals, particularly rare earth elements (REEs). Previous studies have found that REEs in fly ash are largely contained within aluminosilicate glass from which they are difficult to extract. However, these studies have predominantly studied CCR from conventional pulverized coal fired (PCF) plants. PCF plants use higher temperatures (≥1300°C) than do circulating fluidized-bed (CFB) plants (~900-950°C). Samples of feed coal, fly ash, and bottom ash were collected from two adjacent Vietnamese coal-fired power stations, one with a …

Impacts Of Updating Background Groundwater Statistics For Ccr Compliance, May Raad, Molly Reeves

World of Coal Ash Proceedings

In 2017, many power utilities adopted statistical methods to comply with the EPA’s Coal Combustion Residuals (CCR) Rule under the Hazardous and Solid Waste Management System. By 2017–2018, most owners completed initial statistical evaluations for detection and assessment monitoring to meet CCR deadlines. Groundwater sampling and analysis requirements in Parts 257.95, 257.98, and 257.102 are critical for compliance, yet implementation is complex. Subsections 257.93(f) and (g) lack clarity on which statistical tests to apply or how to address distributions and outliers. Additionally, the Rule does not specify when or how to update background threshold values (BTVs), though EPA’s Unified Guidance …

Advancing Ccr Site Management With Rapidly Deployable Gccm Technology For Runoff And Drainage Control, Nathan Ivy

World of Coal Ash Proceedings

GCCM’s were first invented over 20 years ago. These products combine both a concrete – hard armor – top surface for protection and durability and a geomembrane bottom surface for lower permeability. Originally used for erosion control, smaller drainage channel and remediation projects, this presentation discusses the newest iteration in GCCM technology. This product incorporates a 12 mil LLDPE backing which allows for thermal bonding and significant reduction in seepage at the joints. It can be used in a wide variety of applications from drainage ditches and swales to water and wastewater conveyance along with slope protection and erosion control …

Ccr 2026: The Plot Thickens—Your Complete Guide To What’S Next, Mark Rokoff

World of Coal Ash Proceedings

The landscape of CCR management is poised for significant transformation with the proposed EPA regulation introduced in early 2026. This presentation will provide a clear and enhanced summary of the key points in the proposed rule, highlighting the significant changes and implications for the industry. Where appropriate, it will be further enhanced by benchmarking data to compliment the key points and the effect to the “CCR Universe”. The proposed regulation aims to adjust the requirements for effective CCR management, introducing new compliance measures and timelines that will impact owner/operators across the board. Key discussion points will include: • Summary of …

Thermal And Mechanical Activation Of Estonian Oil Shale Cfbc And Hydrated Legacy Fly Ash As An Alternative Binder System For Opc Replacement, Peeter Paaver

World of Coal Ash Proceedings

This study investigates high volume of Ordinary Portland Cement (OPC) substitution with fly ash based calcium sulfoaluminate binder. The utilization of circulating fluidized bed combustion (CFBC) boilers imposes limitations on the recycling of fly ash due to its lower combustion temperature inhibiting the formation of reactive calcium silicate minerals resulting in diminished pozzolanic properties of the ash paste. Our previous research (Paaver et al., 2020, 2022) has demonstrated that the mechanical activation of sulfur and calcium-rich Estonian oil shale CFBC fly ash produces calcium sulfoaluminate (CSA) type active binder allowing high-volume OPC replacement of up to 50%, with a reduction …

Benefits Of Containerized Water Treatment Systems For Coal-Fired Power Plants, Andrew Vincent

World of Coal Ash Proceedings

Containerized systems deliver many of the same functional benefits as housing treatment equipment in permanent buildings, while significantly reducing engineering, construction, and installation costs. By containerizing a water treatment system, a substantial portion of fabrication, assembly, and testing can be completed in a controlled shop environment rather than in the field. This approach greatly reduces on-site labor requirements, mobilization duration, and overall installation complexity. Once delivered to site, containerized systems can be used as permanent installations. Alternatively, they offer the flexibility to be relocated within a plant or transferred between different sites as operational needs change. Multiple containerized systems can …

Rare Earth Element Distribution And Mineral Host In Coal Derived Ash From South African Power Stations, Sanki Biswas, Nicola Wagner, Oftense Moroeng

World of Coal Ash Proceedings

The global shift toward low-carbon energy systems, electric mobility, and digital technologies has sharply increased the demand for critical minerals, including rare earth elements (REY) vital for permanent magnets, batteries, wind turbines, photovoltaic cells, semiconductors, and modern defence applications. Coal by-products—particularly coal fly ash (CFA) and coal bottom ash (CBA)—are emerging as promising secondary sources of REY, but their economic viability depends on effective enrichment and extraction methods. South Africa’s coal-fired power plants generate nearly thirty million tonnes of coal-ash each year. This study investigates REY concentrations in CFA and CBA collected from five major power stations (PS-1 to PS-5) …

Lessons Learned From Managing Ash Pond Closure Waters, Danny Stephens, Tom Geeza, Phil Benson, Ashwin Ranna

World of Coal Ash Proceedings

The water management issues created by ash pond closure are complex and can create technology selection and operational management challenges. Ash dewatering activities produce highly variable effluents, depending on ash composition, aging, and dewatering and stormwater management techniques. Effluent limitations can also be highly variable, depending upon the size of the receiving body and the anticipated composition of the effluent stream. The user often faces competing risks: installing an unnecessarily complex and expensive treatment plant, being limited on closure activities by limitations in water treatment capabilities, or both. This paper presents several lessons learned from assessing ash closure water management …

Epri Ccp Beneficiation Research Update, Benjamin Gallagher, Patrick Webb

World of Coal Ash Proceedings

Coal combustion products (CCPs) are frequently utilized as supplementary materials in cement and concrete manufacturing. With an estimated 2 billion metric tons stored in repositories across the United States, interest in beneficial use has expanded beyond class F fly ash to include ponded and high-LOI ash. Beneficiation provides a critical pathway for managing CCP repositories, particularly under closure-by-removal strategies, and where ash sources have historically been difficult to process. Research conducted at EPRI’s Ash Beneficial Use Center (ABUC) examines the feasibility of processing these ash types into usable products and offers insights into repository variability and classification. Furthermore, the study …