Engineering Commons^™

Tropospheric Attenuation Prediction For Future Millimeter Wave Terrestrial Systems: Estimating Statistics And Extremes, Jinwen Liu, David W. Matolak, Ismail Güvenç, Hani Mehrpouyan

Faculty Publications

Tropospheric attenuations can be significant in the millimeter wave (mmWave) frequency bands; hence, accurate prediction modeling of tropospheric attenuation is important for reliable mmWave communication. Several models have been established by the International Telecommunication Union (ITU), yet estimation accuracy is limited due to the large spatial scales used for model input parameters. In this paper, we address this and apply local precipitation data to analyze tropospheric attenuation statistics and compare to results when using ITU regional input rain data. Specifically, tropospheric attenuation is predicted via simulations using the ITU method at 30, 60, and 90 GHz in four distinct geographic …

Scalable Deeper Graph Neural Networks For High-Performance Materials Property Prediction, Sadman Sadeed Omee, Steph-Yves Louis, Nihang Fu, Lai Wei, Sourin Dey, Rongzhi Dong, Qinyang Li, Jianjun Hu

Faculty Publications

Machine-learning-based materials property prediction models have emerged as a promising approach for new materials discovery, among which the graph neural networks (GNNs) have shown the best performance due to their capability to learn high-level features from crystal structures. However, existing GNN models suffer from their lack of scalability, high hyperparameter tuning complexity, and constrained performance due to over-smoothing. We propose a scalable global graph attention neural network model DeeperGATGNN with differentiable group normalization (DGN) and skip connections for high-performance materials property prediction. Our systematic benchmark studies show that our model achieves the state-of-the-art prediction results on five out of six …

Performance Projection Of A High-Temperature Co2 Transport Membrane Reactor For Combined Co2 Capture And Methane-To-Ethylene Conversion, Xin Li, Kevin Huang, Noah Van Dam, Xinfang Jin

Faculty Publications

Direct conversion of methane into ethylene through the oxidative coupling of methane (OCM) is a technically important reaction. However, conventional co-fed fixed-bed OCM reactors still face serious challenges in conversion and selectivity. In this paper, we apply a finite element model to simulate OCM reaction in a plug-flow CO₂ /O₂ transport membrane (CTM) reactor with a directly captured CO₂ and O₂ mixture as a soft oxidizer. The CTM is made of three phases: molten carbonate, 20% Sm-doped CeO₂ , and LiNiO₂ . The membrane parameters are first validated by CO₂ /O₂ flux …

Chiral Liquid Crystal Microdroplets For Sensing Phospholipid Amphiphiles, Sepideh Norouzi, Jose A. Martinez Gonzalez, Monirosadat (Sanaz) Sadati

Faculty Publications

Designing simple, sensitive, fast, and inexpensive readout devices to detect biological molecules and biomarkers is crucial for early diagnosis and treatments. Here, we have studied the interaction of the chiral liquid crystal (CLC) and biomolecules at the liquid crystal (LC)-droplet interface. CLC droplets with high and low chirality were prepared using a microfluidic device. We explored the reconfiguration of the CLC molecules confined in droplets in the presence of 1,2-diauroyl-sn-glycero3-phosphatidylcholine (DLPC) phospholipid. Cross-polarized optical microscopy and spectrometry techniques were employed to monitor the effect of droplet size and DLPC concentration on the structural reorganization of the CLC molecules. Our results …

A Dual-Band Filtering Structure For Highly Selective Reconfigurable Bandpass Filter And Filtering Balun, Jinqun Ge, Guoan Wang

Faculty Publications

This article proposes a filtering structure consisting of two half-wavelength resonators and two open-stub loaded resonators, which generates two third-order passbands. Multiple transmission zeros are introduced by the newly developed coupling scheme, resulting in extremely sharp roll-off desirable for highly selective filters. The proposed structure is applied to design a PIN-diodes switch-controlled reconfigurable dual-band bandpass filter (BPF) with four-state filtering responses: both passbands ON, both passbands OFF, high-frequency passband ON, and low-frequency passband ON. Stepped-impedance open stubs and one-end-grounded coupled lines are studied and employed in the design to suppress unwanted responses. In addition, two filtering structures are placed symmetrically …

Audio-Based Wildfire Detection On Embedded Systems, Hung-Tien Huang, Austin Downey, Jason D. Bakos

Faculty Publications

The occurrence of wildfires often results in significant fatalities. As wildfires are notorious for their high speed of spread, the ability to identify wildfire at its early stage is essential in quickly obtaining control of the fire and in reducing property loss and preventing loss of life. This work presents a machine learning wildfire detecting data pipeline that can be deployed on embedded systems in remote locations. The proposed data pipeline consists of three main steps: audio preprocessing, feature engineering, and classification. Experiments show that the proposed data pipeline is capable of detecting wildfire effectively with high precision and is …

Zintl Phase Compounds Mg3Sb2-XBiX (X=0, 1, And 2) Monolayers: Electronic, Phonon And Thermoelectric Properties From Ab Initio Calculations, Zheng Chang, Jing Ma, Kunpeng Yuan, Jiongzhi Zheng, Bin Wei, Mohammed Al-Fahdi, Yufei Gao, Xiaoliang Zhang, Hezhu Shao, Ming Hu, Dawei Tang

Faculty Publications

The Mg₃Sb_2−xBi_x family has emerged as the potential candidates for thermoelectric applications due to their ultra-low lattice thermal conductivity (K_L) at room temperature (RT) and structural complexity. Here, using ab initio calculations of the electron-phonon averaged (EPA) approximation coupled with Boltzmann transport equation (BTE), we have studied electronic, phonon and thermoelectric properties of Mg₃Sb_2−xBi_x (x = 0, 1, and 2) monolayers. In violation of common mass-trend expectations, increasing Bi element content with heavier Zintl phase compounds yields an abnormal change in K_L in two-dimensional Mg₃Sb …

Koh Vs Deionized Water Operation In Anion Exchange Membrane Electrolyzers, Noor Ul Hassan, Yiwei Zheng, Paul A. Kohl, Mustain E. William

Faculty Publications

Anion exchange membrane water electrolyzers (AEMELs) have recently received significant attention due to their potential advantages over proton exchange membrane electrolyzers (PEMELs). However, some AEMELs feed an aqueous salt solution to the cell where PEMELs typically feed deionized (DI) water. DI water is preferred to keep the system and maintenance costs low. Because of this, many AEMEL researchers report performance both in the salt solution (typically KOH) and DI water. However, the methodology for switching between KOH and DI water is often poorly defined, and it is unclear what impact the residual salt has on cell performance after switching from …

Sub- And Near-Critical Hydrothermal Carbonization Of Animal Manures, Kyoung S. Ro, Michael A. Jackson, Ariel A. Szogi, David L. Compton, Bryan R. Moser, Nicole D. Berge

Faculty Publications

To produce hydrochar with less volatile matter (VM) and more fixed carbon (FC) to increase its stability, this study compared the hydrothermal carbonization (HTC) of hen (HM) and swine (SM) manures at typical HTC sub-critical temperature of 210 °C and slightly super-critical temperature of 400 °C. Physico-chemical properties such as proximate analysis; ultimate analysis; Brunauer–Emmett–Teller (BET) surface area; higher heating value (HHV); chemical oxygen demand (COD); and inorganic nutrients of hydrochar, gaseous, and liquid products were determined. As expected, both VM and yield decreased with temperature. The heats of HTC reactions were estimated to be exothermic, ranging from −5.7 to …

Antiviral Polymers: A Review, Ali Akbari, Ashkan Bigham, Vahid Rahimkhoei, Sina Sharifi, Esmaiel Jabbari

Faculty Publications

Polymers, due to their high molecular weight, tunable architecture, functionality, and buffering effect for endosomal escape, possess unique properties as a carrier or prophylactic agent in preventing pandemic outbreak of new viruses. Polymers are used as a carrier to reduce the minimum required dose, bioavailability, and therapeutic effectiveness of antiviral agents. Polymers are also used as multifunctional nanomaterials to, directly or indirectly, inhibit viral infections. Multifunctional polymers can interact directly with envelope glycoproteins on the viral surface to block fusion and entry of the virus in the host cell. Polymers can indirectly mobilize the immune system by activating macrophages and …

Editorial For Gels 6th Anniversary Special Issue, Esmaiel Jabbari, Gulden Camci-Unal

Faculty Publications

Note: In lieu of an abstract, this is an excerpt from the first page.

This Special Issue celebrates many outstanding quality papers published in Gels over the past six years since its first issue was published in 2015 [...]

Simplified Thermal Runaway Model For Assisting The Design Of A Novel Safe Li-Ion Battery Pack, Paul T. Coman, Eric C. Darcy, Ralph E. White

Faculty Publications

This paper presents a simplified thermal runaway model (FEM) used to guide the design of a novel battery pack designed to resist thermal runaway propagation passively. The model is based on the heat equation for a 2D geometry with a heat generation term based on the maximum amount of energy measured using a custom-made calorimeter. The model was validated against experimental data using a 48-cell subscale of a full-scale battery pack for three different runs with three trigger cells with Internal Short Circuit Devices (ISCD) implanted in the separators. One trigger cell was placed at the edge, one placed in …

Beyond Profitable Shifts To Green Energies, Towards Energy Sustainability, Farboud Khatami, Erfan Goharian

Faculty Publications

The traditional carbon-based approach towards sustainability has long caused the concepts of green and sustainable energies to be used interchangeably. Recent studies have tried to advance this archaic view by considering more aspects of sustainability. However, almost all major studies have been concerned with only the economic and environmental aspects of electricity generation, whereas the concept of sustainability is beyond these two criteria. In this paper, we seek to provide a methodology for a more comprehensive definition of electricity generation sustainability based on the lessons learned from previous studies and additional metrics suggested by them. The main characteristics of select …

Materialsatlas.Org: A Materials Informatics Web App Platform For Materials Discovery And Survey Of State-Of-The-Art, Jianjun Hu, Stanislav Stefanov, Yuqi Song, Sadman Sadeed Omee, Steph-Yves Louis, Edirisuriya M.D. Siriwardane, Yong Zhao, Lai Wei

Faculty Publications

The availability and easy access of large-scale experimental and computational materials data have enabled the emergence of accelerated development of algorithms and models for materials property prediction, structure prediction, and generative design of materials. However, the lack of user-friendly materials informatics web servers has severely constrained the wide adoption of such tools in the daily practice of materials screening, tinkering, and design space exploration by materials scientists. Herein we first survey current materials informatics web apps and then propose and develop MaterialsAtlas.org, a web-based materials informatics toolbox for materials discovery, which includes a variety of routinely needed tools for exploratory …

Atmospheric Plasma Spraying To Fabricate Metal-Supported Solid Oxide Fuel Cells With Open-Channel Porous Metal Support, Jie Lin, Haixia Li, Wanhua Wang, Peng Qiu, Greg Tao, Kevin Huang, Fanglin Chen

Faculty Publications

Metal-supported solid oxide fuel cells (MS-SOFCs) have been fabricated by applying phase-inversion tape-casting and atmospheric plasma spraying (APS). The effect of the binder amount of the phase-inversion slurries on the microstructure development of the 430L stainless steel metal support was investigated. The pore structures, the viscosity of the slurry, porosity and permeability of the as-prepared metal supports are significantly influenced by the amount of the binder. NiO–scandia-stabilized zirconia (ScSZ) anode, ScSZ electrolyte and La_0.6Sr_0.4Co_0.2Fe0.8O_3−δ (LSCF) cathode layers were consecutively deposited on the metal support with an ideal microstructure by APS process. The effect …

The Effect Of Concrete Material Properties On Rigid Pavement Design In South Carolina, Nicolet Anne Devine

Theses and Dissertations

This thesis presents the effect of concrete material inputs on rigid pavement design in the state of South Carolina. The impact of concrete strength input parameters in the historical AASHTO pavement design method and MEPDG method is investigated using three newly constructed concrete sections, I-85 in Cherokee County, I-20 in Lexington County, and I-85 in Spartanburg County. Strength data obtained from the sections were the result of QA/QC testing provided by the SCDOT during construction, as well as from UofSC laboratory testing. The compressive strength data from these tests was correlated to the elastic modulus and modulus of rupture (which …

Synthesis, Characterization And Evaluation Of Dilute Limit Alloy Bimetallic Catalysts For Bio-Oil Upgrading, Leandro Tagum De Castro

Theses and Dissertations

Well-defined single-atom catalytic sites with unique geometric and electronic properties are at the forefront of catalyst research. One type of SAC is a so-called dilute limit alloy (DLA), where single metal atom sites are supported on (or in) the surface of a second metal. This category of well-dispersed atoms alloyed on a metal surface has shown to be effective in reactions like selective hydrogenation of alkynes and dienes to alkenes, ethanol dehydrogenation, and the Ullmann reaction of aryl chlorides. In biomass conversion, this type of catalyst may find its way to address and improve conversion and yield that are crucial …

Thermal-Hydraulic System Analysis Of A Proposed 1 Mwth Nuclear Gas Cooled Microreactor, Aaron S. Fernandez

Theses and Dissertations

Nuclear power plants have historically been large, expensive, and prolonged construction projects. A new generation of reactors categorized as microreactors is currently being designed to address energy needs in remote locations. The University of South Carolina has proposed the MIcro Nuclear In ONe megawatt (MINION-1) design to achieve ten years of operation. The primary loop transfers 1 MW of energy from the reactor core using helium, while the secondary uses air in an open Brayton cycle to produce power and heat. This work focuses on modeling the MINION-1 design using the System Analysis Module (SAM) developed by Argonne National Labs …

Growth, Characterization And Evaluation Of Cdzntese Single Crystals For Room Temperature Radiation Detectors, Ritwik Nag

Theses and Dissertations

In this research work Cd_0.9Zn_0.1Te_0.03Se_0.97 (CZTS) single crystals were grown using in-house zone refined 7N (99.99999%) purity elements through vertical Bridgman (VBM) method and vertical gradient freeze (VGF) method. The morphological, compositional, and structural characteristics were then performed on the grown CZTS crystals. The x-ray diffraction (XRD) analysis on the grown crystals showed sharp diffraction peaks indicating a highly crystalline nature, with a lattice constant of ~6.45 Å. The elemental and stoichiometric ratio of the grown CZTS crystals were examined by using energy-dispersive x-ray analysis (EDX), which confirmed the formation of the quaternary …

Concurrent Identification, Characterization, And Reconstruction Of Protein Structure And Mixed-Mode Dynamics From Rdc Data Using Redcraft, Hanin Rafiq Omar

Theses and Dissertations

A complete understanding of the structure-function relationship of proteins requires an analysis of their dynamic behaviors and the static structure. However, all current approaches to studying dynamics in proteins have their shortcomings. A conceptually attractive and alternative approach simultaneously characterizes a protein's structure and its intrinsic dynamics⁠. Ideally, such an approach could solely rely on RDC data-carrying both structural and dynamical information. The major bottleneck in utilizing RDC data in recent years has been attributed to a lack of RDC analysis tools capable of extracting the pertinent information embedded within this complex data source.

Here we present a comprehensive strategy …

Catalytic Cracking Of Oxygenated Polymer Waste Via Zeolite Catalysts, Andrew Jaeschke

Theses and Dissertations

Plastic recycling has been a prevalent issue since the commercialization of plastics due to lack of adoption and insufficient technology. There are many different types of plastics used in modern day society; however, majority of recycling efforts are focused solely on polyethylene terephthalate (PET) and polyethylene plastics. Some of these overlooked plastics include polyols and polyurethanes, which can be found in a variety of applications including furniture stuffing, adhesives, and insulation foams. Recently, plastic research has turned to catalytic cracking units as a means of plastic recyclability. Catalytic cracking of hydrocarbons is a field dominated by zeolites catalysts, especially ZSM-5. …

Epitaxial 4h-Sic Radiation Detectors For Harsh Environment Applications, Joshua W. Kleppinger

Theses and Dissertations

Epitaxial 4H-silicon carbide (4H-SiC) is an essential semiconductor material for the development of harsh environment radiation detectors due to its excellent electrical and thermal properties and resistance to radiation damage, opening the door for a wide variety of applications in NASA space missions, nuclear safeguards, and nuclear energy. However, the low atomic numbers of its constituent atoms Si (Z = 14) and C (Z = 6) make 4H-SiC nearly transparent to most neutrally charged radiation which can only be compensated using thicker active volumes.

In this dissertation, Ni/n-4H-SiC Schottky barrier diode (SBD) radiation detectors are fabricated for the first time …

Fundamental Study Of Multiphase Solid/Molten Carbonate Membranes For Co2 Capture And Conversion, Xin Li

Theses and Dissertations

Due to the burning of fossil fuels and human activities, many greenhouse gases such as carbon dioxide are released into the atmosphere, which causes global warming and has a significant negative impact on the human living environment. Therefore, it is imperative to develop carbon capture technologies that can prevent carbon dioxide emission and reduce carbon dioxide concentration in the air. Further, if the captured carbon dioxide can be converted back to fossil fuels, the emission of carbon dioxide is delayed, and more time is gained to develop new and advanced carbon free and clean energy technologies. Motivated by this thought, …

Advancement Of New Solid-Oxide Iron-Air Battery (Soiab) Operated On High-Temperature Oxide-Ion Chemistry, Qiming Tang

Theses and Dissertations

Climate change caused by anthropogenic greenhouse gas (GHG) emissions such as the burning of fossil fuels for power generation and industrial processing is affecting the global climate. To address this critical issue, a transition from fossil energy to renewable energy, especially wind and solar, is necessary. However, to successfully realize this transition, a cost-effective and large-scale stationary electricity storage system is indispensable. In this work, a new type of solid-oxide iron-air battery (SOIAB) operated on high-temperature oxide-ion chemistry is studied for this purpose due to its unique cycling characteristics suitable for large-scale Long Duration Electricity Storage (LDES) applications.

In the …

On Providing Efficient Real-Time Solutions To Motion Planning Problems Of High Complexity, Marios Xanthidis

Theses and Dissertations

The holy grail of robotics is producing robotic systems capable of efficiently executing all the tasks that are hard, or even impossible, for humans. Humans, undoubtedly, from both a hardware and software perspective, are extremely complex systems capable of executing many complicated tasks. Thus, the complexity of many state-of-the-art robotic systems is also expected to progressively increase, with the goal to match or even surpass human abilities. Recent developments have emphasized mostly hardware, providing highly complex robots with exceptional capabilities. On the other hand, they have illustrated that one important bottleneck of realizing such systems as a common reality is …

Highly Active And Stable Low-Pgm And Pgm-Free Catalysts For Anion Exchange Membrane Fuel Cells, Horie Adabi Firouzjaie

Theses and Dissertations

Anion exchange membrane fuel cells (AEMFCs) have recently seen significant growth in interest as their achievable current density, peak power density, and longevity have been dramatically improved. Though these advances in performance have been important for demonstrating the feasibility of the technology, nearly all AEMFCs reported in the literature have required a relatively high loading of platinum group metal (PGM)- based catalysts at both the anode and cathode electrodes. However, to take command of the low-temperature fuel cell market, AEMFCs cannot simply reach the same performance as incumbent proton exchange membrane fuel cells (PEMFCs), which have had decades of development …

Characterization Of Nonequilibrium Plasma Discharge In High Water Vapor Concentration, Malik Mohammad Tahiyat

Theses and Dissertations

In recent years, plasma discharge in liquid medium has been a topic of immense interest. Theoretical efforts have been pursued to obtain insight on physicochemical processes being influenced due to trace water vapor either being present as residual or provided at a known concentration. However, studies on discharge at high vapor content are limited. In this study, discharge characteristics of plasma in high water concentration (> 90%) are investigated experimentally for a pressure range of 1 – 15 Torr to maximize vapor loading without condensation. Voltage-current characteristics were obtained over 0- 14 mA of current for each operating pressure; current …

On The Influence Of Afp-Induced Defects On Mechanical Behavior Of Composite Laminates Under Fatigue Loading, Pierre Chevalier

Theses and Dissertations

The objective of the work presented in this thesis is to propose and validate a numerical solution to quantify the influence of Automated Fiber Placement (AFP) induced defects on the mechanical behavior of conventional composite laminates in fatigue. The work presented here will be divided in six sections. At first, a description of the Automated Fiber Placement process and its associated defects is proposed. In association, two tools developed for a rapid analysis and a progressive damage analysis respectively are discussed and used as an introduction to the work conducted in this thesis. In the second section, an extensive literature …

Observing And Modeling Water Electrolysis Performance Limitations Attributed To Gas Generation And Porous Media Properties, Joseph S. Lopata

Theses and Dissertations

Water electrolysis has been a simple method of hydrogen production for over two centuries, but the exploration of its nuances is still accelerating. This work compiles numerous mechanisms via which electrolysis efficiency is influenced by phenomena that occur within, adjacent to, and nearby functional porous media. Computational and experimental methods are applied to electrolysis systems to quantify the impact of twophase flow patterns and porous media properties on energy losses, primarily those linked directly to the presence of the gas phase.

First, an introduction to the chemistry and operating principle of water electrolysis is presented and relevant works from the …

Rational Synthesis Of Ultra-Small And Durable Platinum-Based Catalysts For Renewable Energy Applications, Fahim Bin Abdur Rahman

Theses and Dissertations

Ultrasmall supported platinum nanoparticles (Pt NPs) are often used in two promising renewable energy production technologies – hybrid-sulfur water splitting for actively catalyzing H2SO4 decomposition and in fuel cells for the oxygen reduction reaction (ORR). However, the stability of Pt NPs under reaction conditions is the ultimate challenge for these processes. Two prevalent ways to overcome this challenge are improving stability by anchoring Pt onto a secondary metal or doping heteroatoms into the support. This dissertation covers the rational design, synthesis, and stabilization of Pt-based catalysts in these two ways to achieve durable catalytic performance with desired activity and selectivity. …