Engineering Commons^™

Fatigue Crack Length Estimation Using Acoustic Emissions Technique-Based Convolutional Neural Networks, Asaad Migot, Ahmed Saaudi, Roshan Joseph, Victor Giurgiutiu

Faculty Publications

Fatigue crack propagation is a critical failure mechanism in engineering structures, requiring meticulous monitoring for timely maintenance. This research introduces a deep learning framework for estimating fatigue fracture length in metallic plates through acoustic emission (AE) signals. AE waveforms recorded during crack growth are transformed into time-frequency images using the Choi–Williams distribution. First, a clustering system is developed to analyze the distribution of the AE image-based dataset. This system employs a CNN-based model to extract features from the input images. The AE dataset is then divided into three categories according to fatigue lengths using the K-means algorithm. Principal Component Analysis …

Polystyrene Nanoplastics As Pfas Carriers And Their Interactions With Zwitterionic Phospholipid Membranes, Jiahuiyu Fang, Tongxuan Qiao, Pranab Sarker, Xiaoxue Qin, Size Zheng, Mark J. Uline, Tao Wei

Faculty Publications

The co-occurrence of per- and polyfluoroalkyl substances (PFAS) and nanoplastics (NPs) poses a synergistic threat to environmental and human health, yet the molecular mechanisms governing PFAS–NP complexation and membrane interactions remain unclear. Using atomistic molecular dynamics simulations, we investigated the adsorption of neutral polytetrafluoroethylene (PTFE) and anionic perfluorinated compounds (perfluorooctanoic acid, PFOA, and perfluorooctanesulfonic acid, PFOS) on polystyrene NPs (3.1 and 6.7 nm) and their interactions with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membranes. Polystyrene NPs act as carriers, transporting PFAS molecules to the lipid/water interface, where PFAS attachment modifies NP interfacial behavior. PFAS adsorption on the NP surface is driven by …

Tuning Oxygen Reduction Kinetics In Lasrcoo4 With Strained Epitaxial Thin Films And Wrinkled Freestanding Membranes, Habib Rostaghi Chalaki, Ebenezer Sessi, Mohammad El Loubani, Dongkyu Lee

Faculty Publications

Sluggish oxygen reduction reaction (ORR) remains a critical barrier to advancing intermediate-temperature electrochemical energy devices. Here, we demonstrate that strain engineering in two platforms, epitaxial thin films and freestanding membranes, systematically tunes ORR kinetics in Ruddlesden-Popper LaSrCoO4. In epitaxial films, film thickness is varied to control in-plane tensile strain, whereas in freestanding membranes strain relaxation during the release step using water-soluble sacrificial layers produces flat or wrinkled architectures. Electrochemical impedance spectroscopy analysis reveals more than an order of magnitude increase in the oxygen surface exchange coefficient for tensile-strained films relative to relaxed films, together with a larger oxygen vacancy concentration. …

Reformulation Of The Protein Databank For Real-Time Search Of Geometrical Attributes Of Protein Structures, Musa Azeem, Christopher Lee, Aaron Hein, Christopher Ott, Homayoun Valafar

Faculty Publications

Introduction:

In this study, we introduce the design and implementation of PDBMine, a large-scale, queryable platform for mining sequence-structure statistics from the Protein Data Bank (PDB). PDBMine enables rapid analysis of local conformational trends across proteins by extracting dihedral angles and sequence patterns at scale. In addition to the design and implementation of PDBMine, we also present results validating its ability to return structurally meaningful information.

Methods:

We first assess the accuracy of its dihedral angle distributions by comparing them to established Ramachandran space and verifying expected behaviors of residues such as glycine and proline. We then use PDBMine to …

Temperature Dependent High Frequency Performance Of A 62% Algan Channel Hemt, Jiahao Chen, Abdullah Al Mamun Mazumder, Parthasarathy Seshadri, Dheekshinn Nandakumar, Ruixin Bai, Rafael Andrew Choudhury, M. Asif Khan, Chirag Gupta

Faculty Publications

This article reports on the temperature dependent performance of a HEMT with an Al_0.62Ga_0.38N channel layer and an Al_0.84Ga_0.16N barrier layer grown by metal–organic chemical vapor deposition. The device in this report was measured at room temperature and elevated temperatures of 100–150 °C. The sheet resistance increased from 3.5 kΩ/sq (25 °C) to 5.4 kΩ/sq (150 °C), while the contact resistance remained nominally similar. For a device with 160 nm gate length and 2 µm source-to-drain length, excellent electrical characteristics have been achieved when the device was operated at 150 °C with …

Stoichiometry-Controlled Surface Reconstructions In Epitaxial Abo3 Perovskites For Sustainable Energy Applications, Habib Rostaghi Chalaki, Ebenezer Seesi, Gene Yang, Mohammad El Loubani, Dongkyu Lee

Faculty Publications

ABO₃ perovskite oxides are a versatile class of materials whose surfaces and interfaces play essential roles in sustainable energy technologies, including catalysis, solid oxide fuel and electrolysis cells, thermoelectrics, and energy-relevant oxide electronics. The interplay between point defects and surface reconstructions strongly affects interfacial stability, charge transport, and catalytic activity under operating conditions. This review summarizes recent progress in understanding how oxygen vacancies, cation nonstoichiometry, and electronic defects couple to atomic-scale surface rearrangements in representative perovskite systems. We first revisit Tasker’s classification of ionic surfaces and clarify how defect chemistry provides compensation mechanisms that stabilize otherwise polar or metastable …

Toward Neurosymbolic Reinforcement Learning Via Editable Specifications, Vedant Khandelwal, Hong Yung Yip, Amit Sheth

Publications

Reinforcement learning systems are commonly adapted to new settings by retraining or fine-tuning policies. This default is costly, difficult to audit, and poorly aligned with structured requirement changes such as revised safety rules, new operational constraints, or updated user preferences. We argue for an alternative abstraction: adaptation via edits to an external, human-readable specification that the agent consults at execution time. We propose conditioning decision-making on an editable knowledge graph encoding (i) rules capturing action applicability and high-level effects, (ii) hard constraints defining feasibility, and (iii) soft preferences shaping tradeoffs among feasible behaviors. Requirement changes become graph edits, not policy …

Mechanistic Roles And Design Criteria For Catalysts In Lithium–Sulfur Batteries, Saheed Lateef, Golareh Jalilvand

Faculty Publications

Catalysis is widely explored in lithium–sulfur (Li–S) batteries to address challenges related to limited capacity and cycle durability. Despite extensive research, catalyst development has often focused on materials without a clear understanding of the mechanistic landscape underlying the complex, multi-step, multi-electron sulfur redox pathway. In fact, our understanding of the thermodynamic, kinetic, and mass transport framework in Li–S systems is still evolving, particularly with respect to the reaction pathways during charge and discharge, and the dynamic evolution of materials in both liquid and solid phases. These evolving insights may fundamentally shift the requirements for catalyst design and future research priorities. …

Degrees Of Rate Control And Autodiff-Driven Direct Sensitivity Analysis In Heterogeneous Catalysis, Olajide H. Bamidele, Sina Behtash, Mubarak Bello, Andreas Heyden

Faculty Publications

Despite the wide application and benefits of the degree of rate control (DRC) analysis, several details remain argued, particularly about the conservation of DRCs at transient (TR) and steady-state (SS) conditions, especially for complex reaction networks. This work argues that previous proofs about the conservation properties of DRCs have been incomplete, and we provide new mathematical proofs at TR and SS conditions. In addition, we use both analytical (automatic differentiation) and numerical (finite difference) approaches to compute DRCs for the case study of ethane hydrogenolysis (EH) over Pt(111). This work confirms that at both TR and SS conditions, the sum …

Extreme Bandgap Al0.63Ga0.37N Quasivertical Schottky Barrier Diodes With A High Baliga Figure Of Merit Of 630 Mw Cm−2, Abdullah Al Mamun Mazumder, Shahab Mollah, Kamal Hussain, Abdullah Mamun, Seongmo Hwang, Tariq Jamil, Grigory Simin, Asif Khan

Faculty Publications

"Extreme bandgap n-Al_0.63Ga_0.37N quasi-vertical Schottky barrier diodes (SBDs) with doping densities of ≈8 × 10¹⁷cm⁻³ (Sample A) and ≈2 × 10¹⁷cm⁻³ (Sample B) are grown on an AlN/sapphire substrate using metalorganic-chemical vapor deposition (MOCVD). Sample A achieves a high forward current density of ≈59.5 kA cm⁻² at 10 V with an I_ON/I_OFF ratio of ≈10⁸ (calculated from the forward current at + 3.8 V and the reverse current at −1 V) and an ideality factor of 2.8. Sample B has a forward current …

Extreme Bandgap Recessed-Gate Metal Oxide Semiconductor Heterostructure Field Effect Transistors With Drain Current 0.28 A Mm−1 And Threshold Voltage −1.5 V, Abdullah Al Mamun Mazumder, Abdullah Mamun, Kenneth Stephenson, Kamal Hussain, Tariq Jamil, Grigory Simin, Asif Khan

Faculty Publications

Herein, the first demonstration of hybrid high-k oxide (ZrO2-Al2O3) incorporation into extreme bandgap (EBG) Al_0.87Ga_0.13N/Al_0.64Ga_0.36N metal-oxide-semiconductor heterostructure field-effect transistors (MOSHFETs) is presented, with both planar and recessed-gate designs on the same AlN/sapphire template with a state-of-the-art low contact resistance of 1.4 Ω mm (contact resistivity, ρc ≈ 5.7 × 10−6 Ω cm2). The recessed-gate MOSHFETs achieve a threshold voltage shift of ΔVTH = 5.8 V, highlighting improved channel control. Static output measurements reveal a peak drain current (IDS) of 340 mA mm⁻¹ for the planar …

Microgrid Black Start Challenges: The Role Of Grid-Forming Inverters, Gab-Su Seo, Wenzong Wang, Behrooz Mirafzal

Faculty Publications

Grid-forming (GFM) inverters are becoming increasingly important for future power systems, particularly in establishing and restarting microgrids after blackouts. The use of GFM inverters enables microgrids to operate independently of utility power and provide key advantages over synchronous generators in black start scenarios, including rapid startup and stable voltage and frequency support for critical loads. However, inverter-driven black start introduces unique challenges and operational considerations. This article examines key challenges and solutions, emphasizing inverter design, control strategies, and microgrid system requirements. Drawing on analysis, simulation, and experimental results, this article highlights the central role of GFM inverters in ensuring reliable …

A Fragility Framework For Surface Erosion With Application To Earthen Dam Breaching, Ege C. Kurter, Ayman Mokhtar Nemnem, M. Hanif Chaudhry, Jasim Imran

Faculty Publications

Overtopping failures of earthen dams are a growing concern under intensifying extreme rainfall. This study introduces a probabilistic fragility framework that combines hydrologic modeling, hydraulic analysis, and soil erodibility to assess erosion risk under uncertain load and resistance. Fragility curves derived from Monte Carlo simulations quantify erosion initiation and severity as functions of rainfall depth and excess shear stress. Application to multiple dams affected during the 2015 South Carolina floods reproduces observed outcomes ranging from complete breach to no damage. The framework also captures cascading effects, where failure of an upstream structure increases downstream loading and erosion potential. Compared with …

A Fragility Framework For Surface Erosion With Application To Earthen Dam Breaching, Ege C. Kurter, Ayman Mokhtar Nemnem, M. Hanif Chaudhry, Jasim Imran

Faculty Publications

Overtopping failures of earthen dams are a growing concern under intensifying extreme rainfall. This study introduces a probabilistic fragility framework that combines hydrologic modeling, hydraulic analysis, and soil erodibility to assess erosion risk under uncertain load and resistance. Fragility curves derived from Monte Carlo simulations quantify erosion initiation and severity as functions of rainfall depth and excess shear stress. Application to multiple dams affected during the 2015 South Carolina floods reproduces observed outcomes ranging from complete breach to no damage. The framework also captures cascading effects, where failure of an upstream structure increases downstream loading and erosion potential. Compared with …

Crisis Observatory: Extracting Credible Signals During A Crisis In The Age Of Llms, Kuan-Chieh Lo, Pranav Maneriker, Sriram Sai Ganesh, Dominik Winecki, Kelly Garrett, Ayaz Hyder, Arnab Nandi, Valerie Shalin, Shannon A. Bowen Ph.D., Amit Sheth, Srinivasan Parthasarathy

Publications

Systems for crisis response have required several different models for the analysis of unstructured text, such as identifying needs, locations, topics, routing, and matching of needs with available responders. Large Language Models (LLMs) have replaced task-specific models across various language processing tasks. However, LLMs are known to be limited by their training data, collected before the crisis. In this demo, we explore the use of LLMs for crisis response scenarios with rapidly evolving information environments. We show how the augmentation of these models with external reliable sources of crisis-specific information can help build adaptive systems for response. The demonstration video …

A Gas-Tight Bonding/Sealing Of Different Bulk Ceramics For Robust Oxygen Separation At Ultra-High Temperatures, Guoan Wang, Xingjian Xue

Faculty Publications

Oxygen transport membrane (OTM) is an economic technology for oxygen separation and high-purity oxygen production. To mitigate various issues induced by high temperatures, intermediate temperature OTM technology has been pursued in recent years. However, in certain circumstances, high operating temperatures are unavoidable, such as in situ oxygen production using OTMs for direct oxy-combustion. Nevertheless, the lack of reliable high temperature gas-tight sealing imposes great challenges on OTM technology for such applications. Herein, a novel sealing strategy is developed to obtain a gas-tight bonding/sealing of two different bulk ceramics using ceramic slurry in combination with phase inversion process. The sealing strategy …

Online Cyber-Physical Neural Network Model For Real-Time Hybrid Simulation, Faisal Nissar Malik, Liang Cao, James Ricles, Austin Downey

Faculty Publications

Real-time hybrid simulation (RTHS) is an experimental testing methodology that divides a structural system into an analyticaland an experimental substructure. The analytical substructure is modeled numerically, and the experimental substructure ismodeled physically in the laboratory. The two substructures are kinematically linked together at their interface degrees of freedom,and the coupled equations of motion are solved in real-time to obtain the response of the complete system. A key challenge inapplying RTHS to large or complex structures is the limited availability of physical devices, which makes it difficult to representall required experimental components simultaneously. The present study addresses this challenge by introducing …

A New Low-Rate Stable Hydrogel Cathode For Aqueous Zn-Ion Batteries, Roya Rajabi, Shichen Sun, Jamil A. Khan, Morgan Stefik, Kevin Huang

Faculty Publications

Aqueous Zn-ion batteries (ZIBs) are attractive candidates for large-scale energy storage owing to the abundance, low cost, and intrinsic safety of Zn metal. However, their practical application is hindered by poor cycle stability, especially at low current densities, due to cathode dissolution and limited electrochemically active sites (EAS). Herein, a hydrogel-based cathode comprising ammonium vanadate, carbon black, and a Zn-ion-conducting carboxymethyl chitosan–acrylamide hydrogel matrix doped with Zn(ClO4)2 is reported. This design establishes a continuous Zn-ion-conducting network, thereby maximizing EAS density throughout the electrode volume. The ZIB with the hydrogel cathode exhibits outstanding cycling stability, with 77% capacity retention after 2000 …

Vertical Sorting Of Bed Material In Gravel-Bed Streams-- Insights From Long-Term Observations In East Creek, British Columbia, Marwan A. Hassan, Tianqi Xing, Conor Mcdowell, Kevin J. Pierce, Mike Turley, Sol Leader-Cole, Enrica Viparelli

Faculty Publications

The vertical sorting of streambed grains is a key control on river channel stability and sediment transport rates. In this study, we report on burial depths and mobility characteristics of coarse sediment in a small gravel-bed stream using an extensive data set of nearly 1,500 magnetically tagged tracer grains, deployed and annually surveyed between 2004 and 2018. We observe that sediment burial correlates with grain size and event magnitude, and we identify correlations between the burial depths of coarse grains and their mobility, residence time, and travel distance characteristics. A particularly large event in 2007 produced significant vertical sorting which …

A Comprehensive Assessment And Benchmark Studyof Large Atomistic Foundation Models For Phonons, Md Zaibul Anam, Ogheneyoma Aghoghovbia, Mohammed Al-Fahdi, Lingyu Kong, Victor Fung, Ming Hu

Faculty Publications

The rapid development of universal machine learning potentials (uMLPs) has enabled efficient, accurate predictions of diverse material properties across broad chemical spaces. While their capability for modeling phonon properties is emerging, systematic benchmarking across chemically diverse systems remains limited. We evaluate six recent uMLPs—EquiformerV2, MatterSim, MACE, and CHGNet—on 2429 crystalline materials from the Open Quantum Materials Database. Models were used to compute atomic forces in displaced supercells, derive interatomic force constants (IFCs), and predict phonon properties including lattice thermal conductivity (LTC), compared with density functional theory and experimental data. The EquiformerV2 pretrained model trained on the OMat24 dataset exhibits strong …

Detecting Polar Ring Galaxies Via Deep Learning, Fawad Kirmani, Anathavishnu S. Unnii, Varsha P. Kulkarni, Kyle Lackey, John R. Rose

Faculty Publications

Polar ring galaxies (PRGs) are peculiar galaxies that show a ring of stars, gas, and dust oriented roughly over the poles of the central ‘host’ galaxy (i.e. roughly orthogonal to the disc of the host galaxy). The formation models for these rings involve mergers or tidal interactions of the host galaxy with another galaxy. Although the identified PRGs look different from each other, they all have a ring that is not in the same plane as the disc of the host galaxy. Unlike in galaxies such as our Milky Way, where stars form in spiral arms, the rings exemplify an …

Electrode Engineering To Minimize Degradation In Lithium-Sulfur Batteries, Saheed Adewale Lateef

Theses and Dissertations

Lithium-Sulfur (Li-S) batteries have recently received significant attention as a potential candidate for next-generation energy storage technology. This is due to its high theoretical capacity (1675 mAh/g) which can provide theoretical energy density of 2500 Wh/kg as compared to 400 Wh/kg of the current Lithium-ion batteries. Moreover, the earth-abundant sulfur element as well as its environmental friendliness endows unique advantages on the cost and environmental impact. However, there are several roadblocks that need to be addressed for commercial adoption of Li-S batteries, such as: (i) poor conductivity of sulfur and its discharged product; (ii) solubility of lithium polysulfides and their …

Influence Of Channel Geometry And Inflow Hydrograph On Hydraulics And Air Volume Around Shafts Of A Stormwater Main, Lylie Vindie Wilkie

Theses and Dissertations

Stormwater management in urban areas is complex, in part because of difficulties related to modeling water flowing in closed conduits, as well as to controlling odor, noise, and pipe corrosion. This thesis summarizes the main findings of a study on how changes in inflow discharge and the geometry of a stormwater main may affect water flow, and how changes in water depth impact air volume and pressure around an air shaft. The study is conducted using CHAN, a one-dimensional model that simulates both flow hydraulics in mains and associated changes in air volume and pressure around air shafts. Main difference …

Ai-Driven Autonomous Manufacturing: A Novel Taxonomy, Vision-Guided Planning, And Diversity-Aware Active Learning Frameworks, Ibrahim Yousif

Theses and Dissertations

Manufacturers face two opposing challenges: the escalating demand for customized products and the pressure to reduce lead times. Current manufacturing equipment, although reliable, operates at the limits of its technology and lacks adaptability to dynamic environments. This trade-off has been described as the optimal degree of automation, a threshold beyond which further automation incurs more cost than benefit. Smart manufacturing has introduced adaptive, data-driven systems, but many deployments still lack the contextual adaptability and autonomous decision-making required to handle unplanned disruptions. This underscores the need for intelligent, autonomous systems capable of real-time adaptation without costly reconfiguration, minimizing human intervention during …

Towards Accurate First-Principles Modeling In Heterogenous Catalysis: Ethane Dehydrogenation And Hydrogenolysis Over Pt Catalysts, Mubarak Ayo Bello

Theses and Dissertations

First-principles modeling has become central to heterogeneous catalysis research, offering mechanistic insight and guiding catalyst design, yet conventional approaches often struggle to accurately describe complex catalytic systems due to methodological uncertainties, simplified assumptions, and the structural diversity of nanoparticle catalysts. This dissertation addresses these challenges using ethane dehydrogenation (EDH) and hydrogenolysis (EH) over platinum catalysts as model systems. The first study benchmarks density functional theory (DFT) functionals against the random phase approximation (RPA) for the EDH network on Pt(111), identifying cost-effective functionals and demonstrating the efficiency of BEEF-vdW ensembles for capturing functional uncertainty. The second study (addressed in prior work) …

Machine-Learning-Assisted Discovery Of Lattice Dynamics Signatures Of Sodium Superionic Conductors, Ogheneyoma Maxwell Aghoghovbia

Theses and Dissertations

Sodium superionic conductors are key to the development of all-solid-state sodium batteries. Discovery of new superionic conductors has traditionally relied on insights from material defect chemistry and the transition/hopping theory, while the role of lattice vibrations, i.e., phonons, remains underexplored. We identify key lattice dynamics signatures that govern ionic conductivity by analyzing the phonon mean squared displacement (MSD) of Na⁺ ions. By high-throughput screening of a dataset of 3903 Na-containing structures, we establish a strong positive correlation between phonon MSD and diffusion coefficients, providing a quantitative correlation between lattice dynamics and ion transport. To accelerate this discovery, we incorporate …

Cold Spray On Fiber Reinforced Polymer Substrates For Composite Repair And Tooling Applications, Patrick Allen Bailey

Theses and Dissertations

Cold Spray technology was first developed in the 1980’s and is an additive manufacturing and repair technique. It works by heating a pressurized carrier gas upwards of 600 °C and inserting metal particles downstream such that when they impact a substrate, the energy transformation causes plastic deformation of the particles. This thesis presents a use case for metal and polymer CS powder on fiber reinforced and fused filament fabrication polymer substrates. The state of the art for CS discusses the most up-to-date research within the field, and where new investigations are required. This research investigates the required process parameters to …

Multiscale Geometric Analysis In Endovascular Therapies: Ex Vivo, In Silico Approaches, Dima Hussein Ali Bani Hani

Theses and Dissertations

In this work, we address a persistent global challenge of vascular disease, specifically peripheral artery disease (PAD), and arteriovenous fistula (AVF) complications in patients with end-stage kidney disease (ESKD). The important role of vascular geometry in disease intervention plans and the development of endovascular therapeutic strategies (e.g., Drug-coated balloon (DCBs)) is critical in addressing these challenges.

This study evaluates the feasibility of co-delivery of paclitaxel (PTX) and valsartan (VAL) using urea-based coatings in DCB, analyzes the coating morphology and microstructural changes to improve therapeutic results. A computational finite element model was developed to complement experimental work, simulate tissue-coating interactions, compute …

Erosion Of Bermuda Grass Covered Soils, Oru-Ntui Johnwatters Nkiri

Theses and Dissertations

Earthen embankments are the most common type of embankment due to the relatively low cost, simplicity, and material availability. However, they are also the most prone to erosion related failure, typically due to overtopping and piping. Research has been conducted to identify ways to control soil erosion and protect earthen embankments with different approaches such as addition of chemicals and biopolymer to the soil, installation of protective layering (geotextiles, concrete), increased soil compaction, and use of vegetation. This thesis considers the use of Bermuda Grass to increase resistance to erosion and protect embankments from failure during overtopping. Grass coverage and …

Gut Microbiome Dynamics In Heart Failure And The Therapeutic Potential Of Nmeg-Cgrp, Kamryn Michael Gleason

Theses and Dissertations

Heart failure (HF) is increasingly recognized as a multisystem disease often linked to gut dysbiosis; however, its specific effects on gut microbial composition remain poorly understood. This study examined long-term changes in the gut microbiome in a murine HF model induced by transverse aortic constriction (TAC) and evaluated the effects of NMEG-CGRP. TAC mimics pressure overload-induced cardiac dysfunction, replicating key features of HF. CGRP, a neuropeptide with vasodilatory and cardioprotective effects, shows potential as a therapy for HF but is limited by rapid degradation. A stabilized analog, NMEG-CGRP, was used to assess its impact on cardiac and gastrointestinal health. Mice …