Digital Commons Network^™

Analysis And Predictive Modeling Of Stall And Spin Accidents In General Aviation Fixed-Wing Aircraft, Mehedi Hasan

Graduate Theses and Dissertations

Stall and spin accidents represent a persistent safety concern in General Aviation, with approximately 41% resulting in fatalities despite their relatively low occurrence. This study analyzes 1,079 General Aviation stall and spin accidents from 2008 to 2023 using the National Transportation Safety Board accident database. Our analysis identified the top phases of flight, injury outcomes, and causal factors in stall/spin accidents. Findings indicate that over 93% of stall/spin events involved General Aviation aircraft, with most accidents occurring during initial climb, takeoff, or low-altitude maneuvering. Pilot-related control errors, especially poor airspeed and angle-of-attack management, were the most common causes. To assess …

Optimization And Simulation Models For Integrating Social Determinants In Assessing And Optimizing The Accessibility And Efficiency Of Community Pharmacy Networks., Md Morshedul Alam

Electronic Theses and Dissertations

Community pharmacies are essential components of the healthcare system, serving not only as points of medication access but also as providers of health consultations and preventive care. However, disparities in pharmacy access persist due to a combination of geographic, socioeconomic, and behavioral factors. This dissertation develops a comprehensive methodological framework to evaluate and improve accessibility to community pharmacies, integrating optimization, choice modeling, and discrete event simulation. First, we develop an Optimal Community-Pharmacy Assignment (OCPA) model to quantify geographic accessibility across a regional population network. The model minimizes risk-adjusted travel distances between population centers and pharmacies, incorporating social determinants of health …

An Active Quasi-Circulator Ic And Technique For 1-255 Mhz Resonance-Based Spectroscopic Impedance Plethysmography, Sharisse Poff

Theses and Dissertations

Impedance measurement is a promising avenue for noninvasive glucosemonitoring. Specifically,resonance-basedimpedancemeasurements exhibit good correlation with glucose levels at excitations from tens of MHztoover 100 MHz. Additionally, plethysmographic impedance measurements are needed to separate arterial blood signals, which contain strongerglucose information, frominterstitialfluidsignals. Weanticipate that plethysmographic measurements across a range of frequencies— spectroscopic plethysmography—at excitations from tens to over 100 MHz could enable resonance-based monitoring with higher selectivity for arterial glucose than previous work. Afour-point impedance measurement circuit is designed, and its ability to measure constant and periodically time-varying impedance is demonstrated. This circuit presents high impedance to the device-undertest (DUT), which fails …

Ai-Driven Uncertainty Quantification & Multi-Physics Approach To Evaluate Cladding Materials In A Microreactor, Alexander Foutch, Kazuma Kobayashi, Ayodeji Babatunde Alajo, Dinesh Kumar, Syed Bahauddin Alam

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The pursuit of enhanced nuclear safety has spurred the development of accident-tolerant cladding (ATC) materials for light water reactors (LWRs). This study investigates the potential of repurposing these ATCs in advanced reactor designs, aiming to expedite material development and reduce costs. The research employs a multi-physics approach, encompassing neutronics, heat transfer, thermodynamics, and structural mechanics, to evaluate four candidate materials (Haynes 230, Zircaloy-4, FeCrAl, and SiC–SiC) within the context of a high-temperature, sodium-cooled microreactor, exemplified by the Kilopower design. While neutronic simulations revealed negligible power profile variations among the materials, finite element analyses highlighted the superior thermal stability of SiC–SiC …

Autoregressive Temporal Modeling For Advanced Tracking-By-Diffusion, Pha Nguyen, Rishi Madhok, Bhiksha Raj, Khoa Luu

Electrical Engineering and Computer Science Faculty Publications and Presentations

Object tracking is a widely studied computer vision task with video and instance analysis applications. While paradigms such as tracking-by-regression,-detection,-attention have advanced the field, generative modeling offers new potential. Although some studies explore the generative process in instance-based understanding tasks, they rely on prediction refinement in the coordinate space rather than the visual domain. Instead, this paper presents Tracking-by-Diffusion, a novel paradigm for object tracking in video, leveraging visual generative models via the perspective of autoregressive models. This paradigm demonstrates broad applicability across point, box, and mask modalities while uniquely enabling textual guidance. We present DIFTracker, a framework that utilizes …

Navigating Transportation Barriers: Older Adults’ Familiarity With New Mobility Options And Perceptions Toward Autonomous Vehicles In Arkansas, Arna Nishita Nithila, Suman Kumar Mitra, Michelle Gray, Alishia Juanelle Ferguson, Jennifer D. Webb

Civil Engineering Faculty Publications and Presentations

The objective of this study is to analyze older adults’ familiarity with new transportation options (ride-hailing services, bike-share services, and shared e-scooter services) and their perception towards autonomous vehicles (fully autonomous cars), as well as how transportation barriers influence their familiarity and perceptions, in Arkansas, a predominantly rural state. Data from 775 older adults aged 60 years or older were collected between October 2021 and October 2022. To fulfill the study objective, the study used Latent Class Cluster Analysis to segment older adults into classes based on their familiarity with new transportation options and their perceptions of autonomous vehicles. The …

Examining Shock Wave Flow Past The Brim Of A Helmet Using Schlieren Imaging, Cody Thomas, Catherine E. Johnson

Mining Engineering Faculty Research & Creative Works

Increasing the protection a helmet provides the user from shock waves can help reduce the prevalence of blast induced traumatic brain injury (bTBI). Previous research has shown that air enters and gets trapped in the helmet-head cavity and can increase the overpressure experienced by the wearer. The brim design of the helmet has yet to be studied to understand how shock waves flow into the helmet. By studying a variety of brims, it is possible that the design can be modified to minimize shock wave flow into the helmet. This paper investigated a shock wave impacting interior and exterior facing …

Resilience Of Interdependent Transportation And Healthcare Systems: A Simulation-Driven Framework Incorporating Social Equity And Facility Optimization, S. Yasaman Ahmadi

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The overarching goal of this dissertation is to develop an integrated, simulation-driven framework to assess and enhance the resilience of interdependent transportation and healthcare systems before, during, and after natural hazards. By examining how spatial disruptions, social vulnerability, operational constraints, and infrastructure interdependencies affect access to and functionality of hospitals, this research offers a multifaceted evaluation of system performance under stress. This dissertation examines the impact of natural hazards, particularly floods, on the interdependent transportation and healthcare systems. The proposed approach combines and advances GIS-based network analysis, graph-theoretical modeling, and discrete-event simulation to evaluate system performance under different scenarios. The …

Curved Confinement Directs Anchoring-Mediated Structural Transitions In Highly Chiral Liquid Crystal Shells, Sepideh Norouzi, Jeremy Money, Stiven Villada-Gil, José Martínez-Gonález, Monirosadat Sadati

Faculty Publications

Cholesteric liquid crystals (CLCs) confined in curved geometries exhibit a rich spectrum of defectmediated morphologies governed by the interplay between chirality, curvature, surface anchoring, and confinement. This study systematically investigates structural transitions in highly chiral CLC shells under asymmetric anchoring conditions, focusing on the effects of shell thickness and curvature on pitch axis reorientation and defect formation. Utilizing microfluidic techniques, we generate core–shell droplets with independently tunable anchoring at inner and outer aqueous interfaces. Transitioning from planar–planar to planar-homeotropic boundary conditions via surfactant-mediated modulation induces profound reorganizations in the director field, giving rise to focal conic domains (FCDs), stripe patterns, …

Development And Evaluation Of Supported Ionic Liquid Membrane And Porphyrin Frameworks For Carbon Capture Separation, Sarang Ismail

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The global urgency to mitigate anthropogenic CO₂ emissions has intensified the pursuit of energy-efficient separation technologies. Supported Ionic Liquid Membranes (SILMs) have emerged as promising candidates for CO₂ capture due to their tunable solubility-selectivity and low energy requirements. However, challenges such as mechanical instability, limited scalability, and trade-offs in transport performance have impeded their widespread adoption.

This thesis explores a systematic approach to designing and optimizing SILMs for enhanced CO₂ separation by tailoring polymer–ionic liquid interactions, processing conditions, and material architectures. A comprehensive set of studies were conducted using poly(vinylidene fluoride) (PVDF) with varying molecular weights, different grades of PEBAX®, …

Impact Of Non-Uniform Surface Temperature On The Apparent Radiative Properties Of Cavity Receivers, Ehsan Mofidipour, Matthew R. Jones, Brian D. Iverson

Faculty Publications

Radiative surface properties play a critical role in the design, analysis and optimization of solar–thermal systems. Cavity receivers increase the efficiency of solar–thermal energy systems through the cavity effect. The cavity effect refers to increased absorption of radiation due to multiple reflections within a cavity. Apparent radiative surface properties of a cavity characterize the effective interactions of radiation passing through an imaginary surface covering the cavity aperture. In this study, we investigate the extent to which the apparent emissivity of a cavity with a non-uniform surface temperature profile may be estimated using an isothermal enclosure model. A cylindrical cavity was …

Genwriter: Reducing Gender Cues In Biographies Through Text Rewriting, Shweta Soundararajan, Sarah Jane Delany

Conference papers

Gendered language is the use of words that indicate an individual’s gender. Though useful in certain context, it can reinforce gender stereotypes and introduce bias, particularly in machine learning models used for tasks like occupation classification. When textual content such as biographies contains gender cues, it can influence model predictions, leading to unfair outcomes such as reduced hiring opportunities for women. To address this issue, we propose GenWriter, an approach that integrates Case-Based Reasoning (CBR) with Large Language Models (LLMs) to rewrite biographies in a way that obfuscates gender while preserving semantic content. We evaluate GenWriter by measuring gender bias …

Revealing Building Operating Carbon Dynamics For Multiple Cities, Winston Yap, Abraham Noah Wu, Clayton Miller, Filip Biljecki

Research Collection College of Integrative Studies

Achieving carbon neutrality is a critical yet elusive goal for many cities, hindered by limited understanding of the relationship between building emissions and their surroundings. To address this challenge, we present a generalizable open science framework that integrates building energy-consumption data, multi-modal geospatial inputs and graph deep learning to quantify building operating emissions and their links to urban form and socio-economic factors. Applying this approach to five cities with diverse climates and planning contexts—Melbourne, New York City (Manhattan), Seattle, Singapore and Washington DC—we demonstrate that our models explain 78.4% of the variation in building operating carbon emissions across cities, achieving …

Stabilization Of Cr³⁺ Using Iron Rich Slag-Derived Phosphate Cement: An Integrated Solution For Heavy Metals And Hazardous Solid Wastes, Ting Huang, Hongyan Ma, Zhongqiu Luo, Xintao Zhou, Zhengqing He, Peiwen Lv, Xiunan Cai, Pingyan Wang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A novel iron-based phosphate cement (IPC), derived from iron-rich smelting slag (ISS), was developed as a sustainable and efficient binder for the stabilization/solidification of trivalent chromium (Cr³⁺). The mechanical properties, hydration behavior, microstructure, leaching toxicity, chromium chemical forms, and environmental safety of chromium-stabilized iron phosphate cement (CIPC) were thoroughly evaluated. The results showed that, with a mass ratio of ISS to ammonium dihydrogen phosphate (ADP) of 2.0, and even with the addition of 20 % chromium nitrate nonahydrate (CN), the compressive strength of CIPC reached 4.2 MPa after curing for 28 d. Furthermore, chromium leaching was well below …

Localized Multivariate Statistical Assessment Of United States Construction Labor Shortages, Ahmed Shiha, Islam H. El-Adaway

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Craft labor shortage is a persistent challenge facing the construction industry across various markets. The historically low geographic mobility of construction labor exacerbates and localizes labor shortages. Several research efforts relied on subjective evaluations to quantify the existence of labor shortages on a national level. As such, there is a lack of empirical quantification of labor shortages at different geospatial levels. This paper fills this knowledge gap. To this end, the authors adopted a methodology that encompassed: (1) conducting a literature review to identify and collect national-level and subnational indicators that explain the changes in labor supply and demand; (2) …

Coupling Effect Of Abrasion And Erosion On Ultrahigh-Performance Seawater-Sea Sand Concrete, Dawei Ding, Wei Zhang, Lanqin Wang, Hongyan Ma, Biqin Dong, Song Han, Hongjian Xu, Dongshuai Hou

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Preparing ultrahigh-performance seawater-sea sand concrete (UHPSSC) to mitigate the scarcity of freshwater and river sand resources has generated considerable recent research interest. However, the deterioration mechanisms of UHPSSC under the effect of abrasion and erosion remain unstudied. In this paper, the underwater steel ball method was conducted to evaluate the impact of seawater, sea sand, steel fiber, and seawater abrasion on the abrasion resistance of UHPSSC. Then the stress erosion models of calcium-silicate-hydrate (C-S-H) were constructed to investigate the degradation mechanisms of UHPSSC under the effect of external stress and seawater erosion. The results show that the application of seawater …

Influence Of Mixing Duration And Absorption Characteristics Of Superabsorbent Polymers On The Fresh And Hardened Properties Of High-Performance Concrete, Yu Cun Gu, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This study investigates the combined influence of superabsorbent polymers (SAPs) with distinct absorption kinetics and extended mixing sequences on the rheological, mechanical, and transport properties of high-performance concrete (HPC). Two SAPs—an ionic acrylamide-co-acrylic acid copolymer (SAP-P) and a non-ionic acrylamide polymer (SAP-B)—were incorporated at an internal curing level of 100%. The impact of extended mixing times (3, 5, and 7 min) following SAP addition was systematically evaluated. Results showed that longer mixing durations led to increased superplasticizer demand and higher plastic viscosity due to continued water absorption by SAPs. However, yield stress remained relatively stable owing to the dispersing effect …

Enhancing Microgrid Protection Through Adaptive Decentralized Relay Coordination: A Solution To Blinding And Sympathetic Tripping, Sujatha Balasubramanian, J. Preetha Roselyn, Prabha Sundaravadivel

Electrical Engineering Faculty Publications and Presentations

Integrating Distributed Energy Resources into microgrids modifies the network’s system parameters and causes it to exhibit behaviour, particularly during fault conditions. This is due to the greater variations in current direction and magnitude. When a microgrid runs in autonomous mode, Distributed Generators result in a reduced short circuit current compared to a system working in grid-connected mode. Microgrid protection issues, namely, blinding of protection, sympathetic tripping, and bidirectional power flow, occur in the power network under such circumstances. The impact of microgrid protection issues and changes in fault current leads to variations of overcurrent relay settings, their operating time and …

Modification Of Tini Alloy By Fast Pulse Laser Heat Treatment, Yitao Chen, Mohammad Masud Parvez, Frank Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this study, the effects of local heat treatment with fast pulse laser on thin TiNi shape memory alloy strip materials were investigated. Various materials characterization methods including optical microscope, scanning electron microscope, atomic force microscope, X-ray diffraction, differential scanning calorimetry, and Vickers hardness were used to identify the differences of microstructure, mechanical properties, and functional properties between regions inside and outside the laser-scanned region. The tensile test was also conducted for both the non-laser-scanned specimen and the laser-scanned specimen. The area covered by laser scanning shows great differences by possessing a more homogeneous austenite phase without shear bands and …

Digital Twins, Ai, And Cybersecurity In Additive Manufacturing: A Comprehensive Review Of Current Trends And Challenges, Md Sazol Ahmmed, Laraib Khan, Muhammad Arif Mahmood, Frank Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The development of Industry 4.0 has accelerated the adoption of sophisticated technologies, including Digital Twins (DTs), Artificial Intelligence (AI), and cybersecurity, within Additive Manufacturing (AM). Enabling real-time monitoring, process optimization, predictive maintenance, and secure data management can redefine conventional manufacturing paradigms. Although their individual importance is increasing, a consistent understanding of how these technologies interact and collectively improve AM procedures is lacking. Focusing on the integration of digital twins (DTs), modular AI, and cybersecurity in AM, this review presents a comprehensive analysis of over 137 research publications from Scopus, Web of Science, Google Scholar, and ResearchGate. The publications are categorized …

Predictors Of Permanent And Temporary Motor Deficits In Patients Undergoing Glioma Resection: A Systematic Review And Meta-Analysis, Brian J. Conway, Stephanie A. Armstrong, Nada Botros, Sergey Tarima, Max O. Krucoff

Biomedical Engineering Faculty Research and Publications

Objective

To identify predictors of permanent and temporary motor deficits in patients undergoing glioma resection.

Methods

A literature search accessed the databases Ovid Medline, Scopus, Web of Science, Cumulative Index to Nursing and Allied Health Literature/EBSCO, PsychInfo, Cochrane, and Wiley for studies reporting motor outcomes following surgical resection of glioma. Outcomes were stratified by patient/tumor characteristics, preoperative condition, and intraoperative factors for both permanent and temporary motor deficits. Generalized estimating equations were used to generate odds ratios.

Results

A total of 1332 titles and abstracts were reviewed resulting in the evaluation of 261 full-text articles. Data were extracted from 67 …

Mantle Flow And Crustal Deformation Revealed By Seismic Anisotropy In The Subduction Zone Beneath Myanmar, Enbo Fan, Mingming Jiang, Yinshuang Ai, Stephen S. Gao, Kelly H. Liu, Yumei He, Yiming Bai, Guangbing Hou, Yuan Ling, Chit Thet Mon, Myo Thant, Kyaing Sein

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The oblique convergence of the Indian and Eurasian plates drives significant deformation in the crust and mantle beneath Myanmar. However, the crustal deformation in the Indo-Burman Ranges (IBR) and mantle flow beneath Myanmar and adjacent areas remain unclear due to limited studies. We utilized data from the newly deployed second phase of the China-Myanmar Geophysical Survey of the Myanmar Orogen array to perform shear wave splitting analysis of PKS, SKKS, and SKS (XKS) phases. Our results, together with previous findings, provide new insights into mantle flow and crustal deformation across central Myanmar. In the IBR, we observed a transition from …

Lithium Slag As A Supplementary Cementitious Material For Sustainable Concrete: A Review, Sajad Razzazan, Nuha S. Mashaan, Themelina Paraskeva

Research outputs 2022 to 2026

The global cement industry remains a significant contributor to carbon dioxide (CO2) emissions, prompting substantial research efforts toward sustainable construction materials. Lithium slag (LS), a by-product of lithium extraction, has attracted attention as a supplementary cementitious material (SCM). This review synthesizes experimental findings on LS replacement levels, fresh-state behavior, mechanical performance (compressive, tensile, and flexural strengths), time-dependent deformation (shrinkage and creep), and durability (sulfate, acid, abrasion, and thermal) of LS-modified concretes. Statistical analysis identifies an optimal LS dosage of 20–30% (average 24%) for maximizing compressive strength and long-term durability, with 40% as a practical upper limit for tensile and flexural …

A Three-Stage Matheuristic For The Blood Stochastic Inventory Routing Problem, Vincent F. Yu, Nabila Salsabila, Aldy Gunawan, Aldy Gunawan, Nurhadi Siswanto

Research Collection School Of Computing and Information Systems

This research introduces a blood distribution system under vendor-managed inventory that considers uncertain supply and demand. We present it as the Blood Stochastic Inventory Routing Problem, formulating it as a two-stage stochastic programming model. To solve this problem, this study proposes a three-stage matheuristic that combines a perturbation heuristic, Adaptive Large Neighborhood Search, and an exact approach. From historical data of Surabaya Blood Center in Indonesia, six sets of new instances are generated under different settings. Computational results show that our proposed three-stage matheuristic outperforms CPLEX and a two-stage matheuristic by gaining optimal or better solutions within a significantly shorter …

Assessing The Robustness Of Test Selection Methods For Deep Neural Networks, Qiang Hu, Yuejun Guo, Xiaofei Xie, Maxime Cordy, Wei Ma, Mike Papadakis, Lei Ma, Yves Le Traon

Research Collection School Of Computing and Information Systems

Regularly testing deep learning-powered systems on newly collected data is critical to ensure their reliability, robustness, and efficacy in real-world applications. This process is demanding due to the significant time and human effort required for labeling new data. While test selection methods alleviate manual labor by labeling and evaluating only a subset of data while meeting testing criteria, we observe that such methods with reported promising results are simply evaluated, e.g., testing on original test data. The question arises: are they always reliable? In this article, we explore when and to what extent test selection methods fail. First, we identify …

Supporting Programmers Answering The Hard-To-Answer Questions Through The Use Of Large Language Models, Haixin Zhou

McKelvey School of Engineering Graduate Student Theses & Dissertations

Programmers often face hard-to-answer questions when working on large-scale projects. Not only during team collaborations, but also during interruptions such as meetings, having to suddenly work on another project, or even just taking a break are major reasons these questions arise, as programmers have to regain the context, knowledge, and mental state to resume the work. Traditional text editors such as GitHub do provide a built-in history system, but they lack historical context behind the editing to answer such questions.

To address this issue, we developed an experimental extension, Code History, on Visual Studio Code (VS Code) in the hope …

Internet Of Things And Modern Digital Evidence Collection, Muhammad T. Haider

Student Theses

The ever-evolving landscape of technology and its innovations are populating our houses, streets and all kinds of industries. The use of smart devices is booming from most developed nations to underdeveloped countries. The complications which come with the use of the Internet of Things has been an active discussion for the past many years. If we look around in a room of 30 people, we will most likely find double the amount of IoT devices than the people in that room. All of those devices are connected to the Internet, and are communicating with data servers across the world. The …

Visceral, Neural, And Immunotoxicity Of Per- And Polyfluoroalkyl Substances: A Mini Review, Pietro Martano, Samira Mahdi, Tong Zhou, Yasmin Barazandegan, Rebecca Iha, Hannah Do, Joel Burken, Paul Ki-Souk Nam, Qingbo Yang, Ruipu Mu

Chemistry Faculty Research & Creative Works

Per- and polyfluoroalkyl substances (PFASs) have gained significant attention due to their widespread distribution in the environment and potential adverse health effects. While ingestion, especially through contaminated drinking water, is considered the primary route of human exposure, recent research suggests that other pathways, such as inhalation and dermal absorption, also play a significant role. This review provides a concise overview of the toxicological impacts of both legacy and emerging PFASs, such as GenX and perfluoro butane sulfonic acid (PFBS), with a particular focus on their effects on the liver, kidneys, and immune and nervous systems, based on findings from recent …

Mining Waste In Asphalt Pavements: A Critical Review Of Waste Rock And Tailings Applications, Adeel Iqbal, Nuha S. Mashaan, Themelina Paraskeva

Research outputs 2022 to 2026

This paper presents a critical and comprehensive review of the application of mining waste, specifically waste rock and tailings, in asphalt pavements, with the aim of synthesizing performance outcomes and identifying key research gaps. A systematic literature search yielded a final dataset of 41 peer-reviewed articles for detailed analysis. Bibliometric analysis indicates a notable upward trend in annual publications, reflecting growing academic and practical interest in this field. Performance-based evaluations demonstrate that mining wastes, particularly iron and copper tailings, have the potential to enhance the high-temperature performance (i.e., rutting resistance) of asphalt binders and mixtures when utilized as fillers or …

Studies Of Electrical Breakdown Of High-Pressure Ultra-Zero Air, Seth Miller

Electrical and Computer Engineering ETDs

High-pressure ultra-zero air is being evaluated to enhance switch performance and serve as a potential replacement for SF$_6$ in high-voltage switches, aiming to reduce reliance on costly insulating gases with supply chain and environmental concerns. There are still uncertainties about the dominant breakdown mechanisms of ultra-zero air in the high-pressure regime. The classical equations for breakdown describing Paschen curves appear to not be valid above 500 psia. In order to better understand gas breakdown in the high-pressure regime, this dissertation is evaluating the basic gas physics breakdown using both uniform and nonuniform-field electrode designs. The data has been collected to …