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Full-Text Articles in Engineering

Reliability-Based Analysis Of Horizontal Curve Design By Evaluating The Impact Of Vehicle Automation On Roadway Departure Crashes And Safety Performance, Omar Al-Sheikh, Seyed Hooman Ghasemi, Mohammad Jalayer Feb 2024

Reliability-Based Analysis Of Horizontal Curve Design By Evaluating The Impact Of Vehicle Automation On Roadway Departure Crashes And Safety Performance, Omar Al-Sheikh, Seyed Hooman Ghasemi, Mohammad Jalayer

Henry M. Rowan College of Engineering Departmental Research

Roadway departure (RwD) crashes are significant safety concerns, especially at horizontal curves. The design of these curves plays a crucial role in mitigating RwD crashes. Thus, a thorough understanding of the interaction between driver behavior, vehicle automation, and geometric design is vital. Substantive safety, which emphasizes the inherent safety in a road's design and function, serves as the foundation of our approach. Building on this, the study employs a safe system approach to investigate the performance of horizontal curves under both non-automated and partially automated conditions, using a reliability-based analysis focusing on Stopping Sight Distance as the primary driver demand. …


Automating Selective Area Electron Diffraction Phase Identification Using Machine Learning, Nathaniel Tomczak, Jennifer Carter Feb 2024

Automating Selective Area Electron Diffraction Phase Identification Using Machine Learning, Nathaniel Tomczak, Jennifer Carter

Faculty Scholarship

Selective area electron diffraction (SAED) patterns can provide valuable insight into the structure of a material. However, the manual identification of collected patterns can be a significant bottleneck in the overall phase classification workflow. In this work, we utilize the recent advances in computer vision and machine learning (ML) to automate the indexing of SAED patterns. The performance of six different ML algorithms is demonstrated using metallic plutonium-zirconium alloys. The most successful approach trained a neural network (NN) to make a classification of the phase and zone axis, and then utilized a second NN to synthesize multiple independent predictions of …


Beneath I-280: Excavating A Neighborhood Lost To San José Freeways, Leila Ullmann, Gordon Douglas Feb 2024

Beneath I-280: Excavating A Neighborhood Lost To San José Freeways, Leila Ullmann, Gordon Douglas

Mineta Transportation Institute

Throughout the 1960s and 1970s, thousands of people in San José, California were displaced from their homes as the state used eminent domain to purchase land and uproot neighborhoods for the construction of Interstate freeways. This report presents a multifaceted research and public knowledge effort that uncovers some of the communities buried beneath these freeways, in the area where I-280 and CA-87 meet today near downtown San José. The project builds primarily from previously unprocessed California Department of Transportation (CalTrans) archival documents, which this project studies for the first time. The records are rich in detail about valuation and sale …


Simple Sars-Cov-2 Concentration Methods For Wastewater Surveillance In Low Resource Settings, Mohammad Dehghan Banadaki, Soroosh Torabi, Alexus Lori Rockward, William Strike, Ann Noble, James W. Keck, Scott M. Berry Feb 2024

Simple Sars-Cov-2 Concentration Methods For Wastewater Surveillance In Low Resource Settings, Mohammad Dehghan Banadaki, Soroosh Torabi, Alexus Lori Rockward, William Strike, Ann Noble, James W. Keck, Scott M. Berry

UK CARES Faculty Publications

Wastewater-based epidemiology (WBE) measures pathogens in wastewater to monitor infectious disease prevalence in communities. Due to the high dilution of pathogens in sewage, a concentration method is often required to achieve reliable biomarker signals. However, most of the current concentration methods rely on expensive equipment and labor-intensive processes, which limits the application of WBE in low-resource settings. Here, we compared the performance of four inexpensive and simple concentration methods to detect SARS-CoV-2 in wastewater samples: Solid Fraction, Porcine Gastric Mucin-conjugated Magnetic Beads, Calcium Flocculation- Citrate Dissolution (CFCD), and Nanotrap® Magnetic Beads (NMBs). The NMBs and CFCD methods yielded the highest …


Generalized Linear Targeting For Cislunar Flight, David Geller, Brayden Barton, David Woffinden Feb 2024

Generalized Linear Targeting For Cislunar Flight, David Geller, Brayden Barton, David Woffinden

Space Dynamics Laboratory Publications

An important element of Artemis and NASA’s campaign to explore the Moon is the autonomous onboard two-level targeter (TLT) used during all cislunar flight phases. The function of the TLT is to autonomously recompute the burn targets for the upcoming burn (or multiple burns) in response to navigation and vehicle dispersion providing a solution that meets all trajectory constraints. Although the TLT has been utilized previously as a ground-based planning tool, and flown onboard during the Artemis I mission, it’s complexity and iterative nature make is difficult to incorporate into and support rapid analyses such as robust optimal trajectory design …


Mathematical Model Of Oxygen, Nutrient, And Drug Transport In Tuberculosis Granulomas, Meenal Datta, Mccarthy Kennedy, Saeed Siri, Laura Via, James W. Baish, Lei Xu, Veronique Dartois, Clifton Barry, Rakesh Jain Feb 2024

Mathematical Model Of Oxygen, Nutrient, And Drug Transport In Tuberculosis Granulomas, Meenal Datta, Mccarthy Kennedy, Saeed Siri, Laura Via, James W. Baish, Lei Xu, Veronique Dartois, Clifton Barry, Rakesh Jain

Faculty Journal Articles

Physiological abnormalities in pulmonary granulomas–pathological hallmarks of tuberculosis (TB)–compromise the transport of oxygen, nutrients, and drugs. In prior studies, we demonstrated mathematically and experimentally that hypoxia and necrosis emerge in the granuloma microenvironment (GME) as a direct result of limited oxygen availability. Building on our initial model of avascular oxygen diffusion, here we explore additional aspects of oxy- gen transport, including the roles of granuloma vasculature, transcapillary transport, plasma dilution, and interstitial convection, followed by cellular metabolism. Approximate analytical solutions are provided for oxygen and glucose concentration, interstitial fluid velocity, interstitial fluid pressure, and the thickness of the convective zone. …


Ion Irradiation And Examination Of Additive Friction Stir Deposited 316 Stainless Steel, Priyanka Agrawa, Ching-Heng Shiau, Aishani Sharma, Zhihan Hu, Megha Dubey, Yu Lu, Lin Shao, Ramprashad Prabhakaran, Yaqiao Wu, Rajiv S. Mishra Feb 2024

Ion Irradiation And Examination Of Additive Friction Stir Deposited 316 Stainless Steel, Priyanka Agrawa, Ching-Heng Shiau, Aishani Sharma, Zhihan Hu, Megha Dubey, Yu Lu, Lin Shao, Ramprashad Prabhakaran, Yaqiao Wu, Rajiv S. Mishra

Materials Science and Engineering Faculty Publications and Presentations

This study explored solid-state additive friction stir deposition (AFSD) as a modular manufacturing technology, with the aim of enabling a more rapid and streamlined on-site fabrication process for large meter-scale nuclear structural components with fully dense parts. Austenitic 316 stainless steel (SS) is an excellent candidate to demonstrate AFSD, as it is a commonly-used structural material for nuclear applications. The microstructural evolution and concomitant changes in mechanical properties after 5 MeV Fe++ ion irradiation were studied comprehensively via transmission electron microscopy and nanoindentation. AFSD-processed 316 SS led to a fine-grained and ultrafine-grained microstructure that resulted in a simultaneous increase …


Interdependencies Between Wildfire-Induced Alterations In Soil Properties, Near-Surface Processes, And Geohazards, Farshid Vahedifard, Masood Abdollahi, Ben A. Leshchinsky, Timothy D. Stark, Mojtaba Sadegh, Amir Aghakouchak Feb 2024

Interdependencies Between Wildfire-Induced Alterations In Soil Properties, Near-Surface Processes, And Geohazards, Farshid Vahedifard, Masood Abdollahi, Ben A. Leshchinsky, Timothy D. Stark, Mojtaba Sadegh, Amir Aghakouchak

Civil Engineering Faculty Publications and Presentations

The frequency, severity, and spatial extent of destructive wildfires have increased in several regions globally over the past decades. While direct impacts from wildfires are devastating, the hazardous legacy of wildfires affects nearby communities long after the flames have been extinguished. Post-wildfire soil conditions control the persistence, severity, and timing of cascading geohazards in burned landscapes. The interplay and feedback between geohazards and wildfire-induced changes to soil properties, land cover conditions, and near-surface and surface processes are still poorly understood. Here, we synthesize wildfire-induced processes that can affect the critical attributes of burned soils and their conditioning of subsequent geohazards. …


Droplet Jump From A Particle Bed, Karl Cardin, Facundo Cabrera-Booman, Raúl Bayoán Cal Feb 2024

Droplet Jump From A Particle Bed, Karl Cardin, Facundo Cabrera-Booman, Raúl Bayoán Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Drop tower experiments have been performed to study droplet jump from a particle bed across a wide range of fluid viscosities. Here the droplet jumps from the particle bed in response to the apparent step reduction from terrestrial gravity to microgravity when the experiment is dropped and enters free fall. The presence of a particle layer has been found to affect contact line dissipation and the overall jumping behavior of droplets. Additionally, the study has identified the impact of the Ohnesorge number (Oh) on droplet morphology. The investigation has yielded results that not only validate a modified version of the …


A Time Synchronized Multi-Hop Mesh Network With Crystal-Free Nodes, Filip Maksimovic, Austin Patel, David C. Burnett, Thomas Watteyne, Kristofer S.J. Pister Feb 2024

A Time Synchronized Multi-Hop Mesh Network With Crystal-Free Nodes, Filip Maksimovic, Austin Patel, David C. Burnett, Thomas Watteyne, Kristofer S.J. Pister

Electrical and Computer Engineering Faculty Publications and Presentations

In this work we propose and demonstrate a protocol for a time synchronized channel hopping mesh network for wireless transceivers that use exclusively imprecise and inaccurate on-chip oscillators. This protocol is built on an IEEE 802.15.4 physical layer radio that enables interoperability with protocols such as 6TiSCH or Thread. A calibration-bootstrapped multi-hop mesh network is demonstrated with a single crystal-enabled node acting as the root. The protocol is designed to create a multi-hop mesh while compensating noisy and drifting oscillators and timers. With a 4 s synchronization period, an experimental implementation of the network maintains, in the worst case, 1.8 …


Advancing Universal Id Through Demonstration Of Enabling Technologies, Joseph Crabtree, Andrew Martin, Jeeyen Koo, Brian Beaven Feb 2024

Advancing Universal Id Through Demonstration Of Enabling Technologies, Joseph Crabtree, Andrew Martin, Jeeyen Koo, Brian Beaven

Kentucky Transportation Center Research Report

The purpose of this project was to install, demonstrate, and evaluate two candidate technologies that could be used to achieve “Universal ID” (i.e., having a unique, electronically readable identifier on every commercial motor vehicle in the United States). The two technologies selected for this demonstration represent (1) a potential low-cost near-term solution (simple RFID tags and roadside readers) and (2) a potential future solution that leverages technology that is anticipated to be installed on all future vehicles to support a variety of connected-vehicle (CV) applications. For this demonstration project, both types of roadside reader technology were installed at three existing …


Inhibited Surface Diffusion In Nanoporous Multi-Principal Element Alloy Thin Films Prepared By Vacuum Thermal Dealloying, Tibra Das Gupta, Thomas John Balk Feb 2024

Inhibited Surface Diffusion In Nanoporous Multi-Principal Element Alloy Thin Films Prepared By Vacuum Thermal Dealloying, Tibra Das Gupta, Thomas John Balk

Chemical and Materials Engineering Faculty Publications

Nanoporous structures with 3D interconnected networks are traditionally made by dealloy- ing a binary precursor. Certain approaches for fabricating these materials have been applied to refrac- tory multi-principal element alloys (RMPEAs), which can be suitable candidates for high-temperature applications. In this study, nanoporous refractory multi-principal element alloys (np-RMPEAs) were fabricated from magnesium-based thin films (VMoNbTaMg) that had been prepared by magnetron sputtering. Vacuum thermal dealloying (VTD), which involves sublimation of a higher vapor pres- sure element, is a novel technique for synthesizing nanoporous refractory elements that are prone to oxidation. When VMoNbTaMg was heated under vacuum, a nanoporous structure was …


The Roles Of Carbonaceous Wastes For Catalysis, Energy, And Environmental Remediation, Chi Huey Ng, Mohd Aizzan Mistoh, Siow Hwa Teo, Andrea Galassi, Hin Taufiq-Yap, Nancy Julius Siambun, Jurry Foo, Coswald Stephen Sipaut, Jeffrey Seay, Jidon Janaun Feb 2024

The Roles Of Carbonaceous Wastes For Catalysis, Energy, And Environmental Remediation, Chi Huey Ng, Mohd Aizzan Mistoh, Siow Hwa Teo, Andrea Galassi, Hin Taufiq-Yap, Nancy Julius Siambun, Jurry Foo, Coswald Stephen Sipaut, Jeffrey Seay, Jidon Janaun

Chemical and Materials Engineering Faculty Publications

This article reviews recent studies about various generations of the carbon materials for their applications in energy and environmental remediation. The synthesis routes of the carbon materials including the condition parameters, interaction of precursors, dopants and carbon materials, as well as their physical/chemical properties are explicated first. Then, the application and mechanism of metal-free/metal-doped/non-metal-doped carbon materials are discussed in detail. Lastly, this review is ended with a summary and invigorating perspectives on the challenges and future directions at the forefront of the catalysis platform to take a step further for real application.


Effects Of Laser Defocusing On Bead Geometry In Coaxial Titanium Wire-Based Laser Metal Deposition, Remy Mathenia, Aaron Flood, Braden Mclain, Todd Sparks, Frank W. Liou Feb 2024

Effects Of Laser Defocusing On Bead Geometry In Coaxial Titanium Wire-Based Laser Metal Deposition, Remy Mathenia, Aaron Flood, Braden Mclain, Todd Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Coaxial wire-based laser metal deposition is a versatile and efficient additive process that can achieve a high deposition rate in the manufacturing of complex structures. In this paper, a three-beam coaxial wire system is studied, with particular attention to the effects of deposition height and laser defocusing on the resulting bead geometry. As the deposition standoff distance changes, so does the workpiece illumination proportion, which describes the ratio of energy going directly into the feedstock wire and into the substrate. Single titanium beads are deposited at varying defocus levels and deposition rates and the bead aspect ratio is measured and …


Adaptive Inter-Vehicular Collaboration For Level 5 Autonomous Driving, Sumbal Malik Feb 2024

Adaptive Inter-Vehicular Collaboration For Level 5 Autonomous Driving, Sumbal Malik

Dissertations

The evolution of sensor technologies, mobile networks, and artificial intelligence has significantly expanded the horizons of various sectors, notably in autonomous driving. According to the World Health Organization, over 1.3 million people succumb to traffic accidents annually, predominantly due to human negligence. Complex urban environments, characterized by mixed traffic flow involving Human Driven Vehicles and Connected and Autonomous Vehicles, intricate traffic patterns, frequent lane changes, and slow speeds, face escalating challenges related to traffic accidents and congestion. These challenges lead to wasted time, increased fuel consumption, and heightened pollution emission levels. Hence, the development of a safe and robust version …


Investigating The Structure And Performance Of Electrodes Made By Dry And Wet Slurry Processes, Kubra Uzun, Bhamiti Sharma, Bradley R. Frieberg, Ming Wang, Jiazhi Hu, Anita Li, Xiaosong Huang, Yang-Tse Cheng Feb 2024

Investigating The Structure And Performance Of Electrodes Made By Dry And Wet Slurry Processes, Kubra Uzun, Bhamiti Sharma, Bradley R. Frieberg, Ming Wang, Jiazhi Hu, Anita Li, Xiaosong Huang, Yang-Tse Cheng

Chemical and Materials Engineering Faculty Publications

Performance, cost, and safety are vital factors in producing and handling lithium-ion batteries. Using a dry process reduces the cost and environmental impact of producing large-scale lithium-ion battery electrodes significantly as solvents are eliminated. Thus, in this study, solvent-free dry electrostatic spray deposition (ESD) and conventional slurry processes were compared to uncover the influence of the manufacturing process on thick LiNi 0.8Mn0.1Co 0.1O 2 (NMC 811) positive electrodes. More pressure during calendering was found necessary for the dry-made (dry) electrodes to have the same porosity, leading to more cracks within the NMC particles and better adhesion. At slower discharge rates, …


02.26.2024 Orsp Connect, Liz Williamson Feb 2024

02.26.2024 Orsp Connect, Liz Williamson

ORED Newsletter

No abstract provided.


02.12.2024 Orsp Connect, Liz Williamson Feb 2024

02.12.2024 Orsp Connect, Liz Williamson

ORED Newsletter

I-RED Program, Training on Python and R available, Christy White spotlight, UM Researchers Find Turmeric, Thyme Oils Repel Fire Ants


02.05.2024 Orsp Connect, Liz Williamson Feb 2024

02.05.2024 Orsp Connect, Liz Williamson

ORED Newsletter

NSF Revises PAPPG, Mickey McLaurin spotlight, ORSP Training Available: NSF Project Summary, Inclusive Entrepreneurship Event


Two-Scale Data-Driven Design For Heat Manipulation, Daicong Da, Wei Chen Feb 2024

Two-Scale Data-Driven Design For Heat Manipulation, Daicong Da, Wei Chen

Mechanical and Biomedical Engineering Faculty Publications and Presentations

Data-driven methods have gained increasing attention in computational mechanics and design. This study investigates a two-scale data-driven design for thermal metamaterials with various functionalities. To address the complexity of multiscale design, the design variables are chosen as the components of the homogenized thermal conductivity matrix originating from the lower scale unit cells. Multiple macroscopic functionalities including thermal cloak, thermal concentrator, thermal rotator/inverter, and their combinations, are achieved using the developed approach. Sensitivity analysis is performed to determine the effect of each design variable on the desired functionalities, which is then incorporated into topology optimization. Geometric extraction demonstrates an excellent matching …


Evolvement Of Excusable Delay Clauses In Government Contracts Since The Covid-19 Pandemic, Jung Hyun Lee, Yunping Liang, Seyed Mohammad Ehsan Tabatabaee, Bryce Riccitelli Feb 2024

Evolvement Of Excusable Delay Clauses In Government Contracts Since The Covid-19 Pandemic, Jung Hyun Lee, Yunping Liang, Seyed Mohammad Ehsan Tabatabaee, Bryce Riccitelli

Durham School of Architectural Engineering and Construction: Faculty Publications

Excusable delay clauses in government construction contracts, often considered boilerplate with minimal modifications, have increased in attention since the outbreak of COVID-19. Despite the studies enumerating triggering events of the clause in the background of the pandemic, it is necessary to capture insights into how the unprecedented event is systematically accommodated by contract languages. The overarching goal of this study is to identify changes in contract languages over the pre-and post-pandemic eras by state departments of transportation (DOTs), focusing on excusable delay clauses. This study conducts a content analysis and a comparative analysis of state DOT construction contract documents, including …


Experimental Investigation Of A Heat Pump Tumble Dryer With A Zeotropic Refrigerant Mixture, Melanie Cop, Riley Barta, Christiane Thomas, Ulrich Hesse Feb 2024

Experimental Investigation Of A Heat Pump Tumble Dryer With A Zeotropic Refrigerant Mixture, Melanie Cop, Riley Barta, Christiane Thomas, Ulrich Hesse

School of Mechanical Engineering Faculty Publications

Due to their high global warming potential (GWP), fluorinated refrigerants are being replaced in many heat pump and refrigeration systems. Especially in small systems such as heat pump tumble dryers (HPTD), the replacement of the globally used working fluid in this application, R134a, appears to be manageable. One established alternative is the use of hydrocarbon refrigerants. Within this research project, new zeotropic refrigerant blends of hydrocarbons are theoretically evaluated as retrofit substitutes for R134a in heat pump tumble dryers. The aim is to use the temperature glide inherent to zeotropic mixtures during phase change to increase the heat transfer efficiency …


Estimation Of Co2 Absorption By A Hybrid Aqueous Solution Of Amino Acid Salt With Amine, Farid Amirkhani, Amir Dashti, Hossein Abedsoltan, Amir H. Mohammadi Feb 2024

Estimation Of Co2 Absorption By A Hybrid Aqueous Solution Of Amino Acid Salt With Amine, Farid Amirkhani, Amir Dashti, Hossein Abedsoltan, Amir H. Mohammadi

Chemical and Biochemical Engineering Faculty Research & Creative Works

Four developed machine learning algorithms are proposed to prognosticate the CO2 solubility in amino acid salt solutions, blended with amine solutions as additives, in broad ranges of temperature and pressure. From literature 375 experimental data points for CO2 solubility were collected. The results from the applied algorithms indicated that the CO2 solubility is estimated acceptably close to the experimental values. In the best case, the developed network estimates CO2 solubility in the stated solutions with an average relative deviation of 6.53 % and a correlation coefficient of 0.9892.


Construction Software: Use, Selection, And Performance In Low-Bid Contracting, David R. Cazares Feb 2024

Construction Software: Use, Selection, And Performance In Low-Bid Contracting, David R. Cazares

Construction Management

The qualitative research included in this study evaluates the use, selection, and perceived gaps of current construction software suits in low-bid contracting. In addition, the data aims to provide merit to the correlation between construction software use and company performance. The intended stakeholders of this study include entrepreneurs in software development and construction, along with researchers looking to gather knowledge pertaining to this niche industry. Through a Google Forms questionnaire distributed via email, participants provide insight on the current status quo. The study’s responses show clear trends in the types of software currently in use and the subsequent reasons for …


Mission-Driven Inverse Design Of Blended Wing Body Aircraft With Machine Learning, Rohan S. Sharma, Serhat Hosder Feb 2024

Mission-Driven Inverse Design Of Blended Wing Body Aircraft With Machine Learning, Rohan S. Sharma, Serhat Hosder

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The intent of this work was to investigate the feasibility of developing machine learning models for calculating values of airplane configuration design variables when provided time-series, mission-informed performance data. Shallow artificial neural networks were developed, trained, and tested using data pertaining to the blended wing body (BWB) class of aerospace vehicles. Configuration design parameters were varied using a Latin-hypercube sampling scheme. These data were used by a parametric-based BWB configuration generator to create unique BWBs. Performance for each configuration was obtained via a performance estimation tool. Training and testing of neural networks were conducted using a K-fold cross-validation scheme. A …


Us Public Opinion About The Safety Of Gene Editing In The Agriculture And Medical Fields And The Amount Of Evidence Needed To Improve Opinions, Brandon R. Mcfadden, Joy N. Rumble, Kathryn A. Stofer, Kevin M. Folta Feb 2024

Us Public Opinion About The Safety Of Gene Editing In The Agriculture And Medical Fields And The Amount Of Evidence Needed To Improve Opinions, Brandon R. Mcfadden, Joy N. Rumble, Kathryn A. Stofer, Kevin M. Folta

Agricultural Economics and Agribusiness Faculty Publications and Presentations

Introduction: Implementation of gene editing in agriculture and medicine hinges on public acceptance. The objectives of this study were to explore U.S. public opinion about gene editing in agricultural and medical fields and to provide more insight into the relationship between opinions about the safety of gene editing and the potential impact of evidence to improve opinions about safety.

Methods: Data were from two samples of U.S. respondents: 1,442 respondents in 2021 and 3,125 respondents in 2022. Survey respondents provided their opinions about the safety of gene editing in the agricultural and medical fields and answered questions about the number …


Broadening Participation Of Teachers In Computing: Examining Postsecondary Educational Experiences And Prospective Educators’ Cs Teaching Interests, Robert Schwarzhaupt, Alexsandra Galanis, Joanna Goode, Kate Blanchard, Jill Bowdon, Joseph P. Wilson Feb 2024

Broadening Participation Of Teachers In Computing: Examining Postsecondary Educational Experiences And Prospective Educators’ Cs Teaching Interests, Robert Schwarzhaupt, Alexsandra Galanis, Joanna Goode, Kate Blanchard, Jill Bowdon, Joseph P. Wilson

Journal of Computer Science Integration

Teacher shortages in K–12 computer science (CS) education negatively impact students’ access to CS courses, exposure to CS concepts, and interest in CS-related careers. To address CS teacher shortages, this study seeks to understand factors related to expressing a preference to teach CS among prospective teachers. The study team analyzed data from 27,700 prospective teacher applications accepted into the 2016–2020 Teach For America (TFA) corps (cohorts). The TFA corps is an alternative teacher development program that recruits and prepares participants to obtain their teaching certification while they work for at least two years in underserved communities on a temporary teaching …


Characterizing Linearizable Qaps By The Level-1 Reformulation-Linearization Technique, Lucas Waddell, Warren Adams Feb 2024

Characterizing Linearizable Qaps By The Level-1 Reformulation-Linearization Technique, Lucas Waddell, Warren Adams

Faculty Journal Articles

The quadratic assignment problem (QAP) is an extremely challenging NP-hard combinatorial optimization program. Due to its difficulty, a research emphasis has been to identify special cases that are polynomially solvable. Included within this emphasis are instances which are linearizable; that is, which can be rewritten as a linear assignment problem having the property that the objective function value is preserved at all feasible solutions. Various known sufficient conditions for identifying linearizable instances have been explained in terms of the continuous relaxation of a weakened version of the level-1 reformulation-linearization-technique (RLT) form that does not enforce nonnegativity on a subset …


Residual Optical Absorption From Native Defects In Cdsip2 Crystals, Timothy D. Gustafson, Nancy C. Giles, Elizabeth M. Scherrer, Kevin T. Zawilski, Peter G. Schunemann, Kent L. Averett, Jonathan E. Slagle, Larry E. Halliburton Feb 2024

Residual Optical Absorption From Native Defects In Cdsip2 Crystals, Timothy D. Gustafson, Nancy C. Giles, Elizabeth M. Scherrer, Kevin T. Zawilski, Peter G. Schunemann, Kent L. Averett, Jonathan E. Slagle, Larry E. Halliburton

Faculty Publications

CdSiP2 crystals are used in optical parametric oscillators to produce tunable output in the mid-infrared. As expected, the performance of the OPOs is adversely affected by residual optical absorption from native defects that are unintentionally present in the crystals. Electron paramagnetic resonance (EPR) identifies these native defects. Singly ionized silicon vacancies (V-Si) are responsible for broad optical absorption bands peaking near 800, 1033, and 1907 nm. A fourth absorption band, peaking near 630 nm, does not involve silicon vacancies. Exposure to 1064 nm light when the temperature of the CdSiP2 crystal is near 80K converts …


Identification Of Early Opportunities For Simultaneous H2 Separation And Co2 Storage Using Depleted Coal Seams, Masoud Aslannezhad, Mohammad Sayyafzadeh, Stefan Iglauer, Alireza Keshavarz Feb 2024

Identification Of Early Opportunities For Simultaneous H2 Separation And Co2 Storage Using Depleted Coal Seams, Masoud Aslannezhad, Mohammad Sayyafzadeh, Stefan Iglauer, Alireza Keshavarz

Research outputs 2022 to 2026

Hydrogen (H2) production by steam methane reforming (SMR) is an economically viable technique on a commercial scale. However, this process produces large amounts of carbon dioxide (CO2), which eventually negates the benefits of employing H2 as an industrial input and clean energy carrier. This issue has led to increasing interest in capturing CO2 emissions from SMR to produce H2. This study proposes and investigates the use of coalbed methane (CBM) resources for separating the mixture of H2 and CO2 gases. The competitive adsorption mechanism in CBM not only can separate the H2 gas from the mixture but also results into …