Engineering Commons^™

Evaluation Of Unreinforced And Geosynthetic-Reinforced Subgrade Material Performance With Large-Scale Tracking Wheel Tests And Dynamic Cone Penetrometer Tests, Kenaz Owusu

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Subgrade has a significant impact on the performance of a pavement as it serves as the foundation layer on which traffic loads are transferred. Many pavement failures can be attributed to weak subgrade strength. The integration of geosynthetics in road pavements has been identified as an effective solution for enhancing subgrade performance to withstand imposed traffic. This study evaluated the performance of unreinforced and geosynthetic-reinforced subgrades in Nebraska to quantify the contribution of geosynthetics to unpaved layer systems.

The strength and stiffness of different soil subgrades were assessed through unconfined compressive strength tests and repeated load triaxial (RLT) tests, which …

Smart Automatic Modal Hammer Predictor–Corrector Approach For Accurate Excitation Of Dynamical Systems, Mohammad Nasr

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

This research introduces an innovative solution that revolutionizes the study of linear and nonlinear dynamical systems—a smart automatic modal hammer. With its affordability and intelligent capabilities, this automatic modal hammer becomes an invaluable tool for research and industry, enabling repeatable strikes with precise force control. This system's significance becomes particularly evident when studying nonlinear systems, which heavily rely on the excitation level for their dynamics. By offering a cost-effective design this proposed system proves to be robust in accelerating research on nonlinear dynamics, providing researchers with an efficient and accessible means to delve deeper into these complex systems. The proposed …

Ultrasonic Nondestructive Quantification Of Case Depth In Railroad Bearing Components, Trevor K. Adelung

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

While in service, railroad bearings must withstand large loads to ensure smooth operation. These large loads can lead to failure due to rolling contact fatigue (RCF), for which small cracks initiate just beneath the surface of the components. As a preventative measure, bearings are manufactured with a hardened surface layer called the effective case depth (ECD). Current methods in industry use destructive hardness testing to quantify the ECD. While accurate, this method is costly and time consuming. Ultrasonic nondestructive testing would provide a more efficient and cost-effective method to determine ECD. In this thesis, diffuse ultrasonic shear backscatter was used …

Studies Of Exotic Electronic, Optical, And Electrochemical Properties In Nanoparticle Assembly And Graphene, Jay Min Lim

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

It is well known that exotic properties and phenomena emerge as structural dimensions shrink to nanoscales. We self-assembled one-dimensional chains of gold nanoparticles in solution and quantified the growth process by monitoring the redshift of localized surface plasmon resonance (LSPR). Curiously, the redshift stopped while the chains continued to rearrange as manifested by gradual reduction in the LSPR peak. Using electromagnetic simulations, we quantitatively explained the phenomena as a rapid “addition-polymerization” followed by a sharp transition to “condensation-process.” Next, recognizing the significant electric field enhancement in the interparticle gap, a photoluminescent-active Eu³⁺ ion was used to probe Surface-Enhanced Photoluminescence …

Nanoparticle-Based Approaches To Brain Injury And Studies For Improved Detectability Toward Better Delivery Characterization, Hunter A. Miller

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

The clinical translation of nanoparticle (NP) therapeutics for brain injury has been slow despite preclinical promise. The causes of disconnect between preclinical and clinical outcomes is multifactorial, but insufficient delivery is noteworthy. Preclinical delivery characterization often lacks, obscuring mechanisms of failure, slowing development. Multimodal imaging is a promising strategy to improve delivery characterization, combining the strengths of various modalities. Magnetic resonance imaging (MRI) and luminescence imaging are a suitable combination for multimodal imaging, expanding the spatial and temporal resolution of either alone, but further material development is needed to enhance detectability. One problem is the interference of cellular autofluorescence in …

Computational Studies Of Charge-Transfer Mechanisms In Electrochemical Materials, Mohammadreza Reza Nouri

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

Understanding charge transfer mechanisms of electrochemical reactions is critical for advancing a variety of electrochemical energy storage and conversion technologies such as water electrolysis, fuel cells, and batteries. (Photo)electrochemical water splitting, involving OER at the anode and HER at the cathode, presents an environmentally friendly way of storing energy from renewable sources in the form of pure hydrogen. While a lot of emphasis has been placed on developing highly active and stable OER/HER catalysts, our atomic-level understanding of the underlying charge transfer mechanisms falls behind.

In this work, we focus on both Faradaic and non-Faradaic charge transfer mechanisms to investigate …

Enhanced Optical And Infrared Activity Of Nanosphere Dimers Attributed To Dimer Geometry, D. Keith Roper, Jin-Woo Kim, Ricardo R. Romo, Joseph Batta-Mpouma

Biological and Agricultural Engineering Faculty Publications and Presentations

Enhanced optical and infrared activity of subwavelength metal nanoparticles is key to their use in optoelectronics, spectroscopy, and sensing. The present work compared spectra of nanosphere dimers merged by centrifuging gold nanospheres with corresponding simulated nanoscale dimers. Geometric features of the nanosphere dimers were related to corresponding optical and near-infrared activity through simulation. Differences in optical and infrared activity of the nanosphere dimers were largely attributable to changes in the radius of the nanosphere and the radius of the conductive junction between merged nanospheres. The features observed in the experimental spectra were attributed to a select number of dimers exhibiting …

Magnetization And Age Of Ca. 544 Ma Syenite, Eastern Canada: Evidence For Renewal Of The Geodynamo, Tinghong Zhou, Mauricio Ibañez-Mejia, Richard K. Bono, Rory D. Cottrell, Wouter Bleeker, Kenneth P. Kodama, Wentao Huang, Eric G. Blackman, Francis Nimmo, Aleksey Smirnov, John A. Tarduno

Michigan Tech Publications

The ca. 565 Ma Ediacaran geodynamo was highly unusual, producing an ultralow field 10 times weaker than present-day value of 8 x 1022 A m2. A ∼5 times rise in field strength is seen in time-averaged single crystal paleointensity data of ca. 532 Ma Early Cambrian anorthosites of Oklahoma (USA). The field increase could record the onset of inner core nucleation predicted by thermal evolution and numerical dynamo models. Here, we examine the renewal of the geodynamo through zircon U-Pb geochronology and single crystal paleointensity studies of plagioclase from the Chatham-Grenville syenite intrusion in the Grenville Province (Canada). U-Pb data …

Magnetic Sensor Compensation Utilizing Factor Graph Estimation, Frederic W. Lathrop, Clark N. Taylor, Aaron Nielsen

Faculty Publications

Recently, there has been significant interest in the ability to navigate without GPS using the magnetic anomaly field of the Earth (magnav). One of the key technical bottlenecks to achieving magnav is obtaining an accurate magnetic sensor calibration, taking into account own-ship and sensor effects. The Tolles-Lawson magnetic calibration method continues to be the industry standard and was developed when airborne magnetic survey aircraft were first employed over 70 years ago. In this paper, we present a magnetic calibration algorithm based on a factor graph optimization using inertial measurements as well as inputs from both a vector and scalar magnetometer. …

In-Situ Micro-Ct Analysis Of Deformation Behavior In Sandwich-Structured Meta-Stable Beta Ti−35nb Alloy, Yu Jing Lui, Zi Lin Zhang, Jin Cheng Wang, Xiang Wu, Xiao Chun Liu, Wei Ying Huang, Lai Chang Zhang

Research outputs 2022 to 2026

Beta Ti−35Nb sandwich-structured composites with various reinforcing layers were designed and produced using additive manufacturing (AM) to achieve a balance between light weight and high strength. The impact of reinforcing layers on the compressive deformation behavior of porous composites was investigated through micro- computed tomography (Micro-CT) and finite element method (FEM) analyses. The results indicate that the addition of reinforcement layers to sandwich structures can significantly enhance the compressive yield strength and energy absorption capacity of porous metal structures; Micro-CT in-situ observation shows that the strain of the porous structure without the reinforcing layer is concentrated in the middle region, …

Organizational Reliability And Resilience As A Dynamic System: Knowledge Modeling With Fuzzy Cognitive Maps, Antonie J. Jetter, Ahmed A. Alibage, Nan Peter Liang

Engineering and Technology Management Faculty Publications and Presentations

Safety research in complex environments recommends that high-hazard industries improve reliability and increase their capacity for resilience by enacting principles for high-reliability organizing (HRO). This view has been highly influential in many industries, ranging from aviation to hospitals, and is at the core of many safety culture programs. However, even though HRO principles originated in business practice and were observed in diverse organizations, practitioners frequently struggle to enact them in the contexts of their work. This is likely caused by two limitations of current research: principles are insufficiently specified and the interdependencies between them, such as mutually reinforcing vs. tradeoff …

Power Resilience Planning Under The Threat Of Artificial Intelligence, Chip Corbett, Cuong Nguyen, Dahm M. Hongchai, Prajakta Thorat, Pavithra Prasad, Sarah Von Schimmelmann, Charles M. Weber, Timothy R. Anderson

Engineering and Technology Management Faculty Publications and Presentations

The earth is an unstable planet. Change is constant and frequently chaotic. It is very important to plan carefully to manage changes that can be anticipated now, and to cover potential issues that might not yet have been discovered. The dawn of artificial intelligence (AI) presents a host of new concerns and opportunities. The criteria for evaluation are diverse and complex. Cybersecurity is absolutely essential, yet advances in technology have created an internet of things (IoT) where threat vectors might gain access to critical command and control elements through trillions of connected IoT devices. Whereas elegant zero trust cybersecurity models …

Quantifying Relationships In Fuzzy Cognitive Maps Based On Content Analysis Of Unstructured Research Texts, Ahmed Alibage, Antonie J. Jetter, Elpiniki Papageorgiou

Engineering and Technology Management Faculty Publications and Presentations

FCM projects often rely on knowledge-based approaches, such as expert interviews, which can be challenging to conduct because they require extensive expert participation. We propose a novel alternative to create FCM models based on expert knowledge that is already codified in research texts and other publications. In this approach, thematic network analysis identifies FCM concepts and signed causal connections, while computation of t-coefficient is used to determine the weights of the identified edges. We introduce and evaluate the approach in the context of a real-world system modeling project that is based on 47 carefully selected, peer reviewed research publications on …

Five Pivotal Practices For Leaders To Cultivate Empathy Within Virtual Scrum Teams, Dahm Mongkol Hongchai, Charles M. Weber

Engineering and Technology Management Faculty Publications and Presentations

In the digital and global economy, business leaders need more than just business and technology competencies; they also require empathy. However, there is a notable scarcity of research on empathy in Scrum for product development. This study aims to uncover critical insights into how leaders can foster empathy within virtual Scrum teams. Accordingly, this paper proposes five pivotal themes leaders can employ: Scrum fundamentals, meditation, self- and other-analysis, healthy interactions, and informal connections. These vital strategies offer actionable methods for leaders seeking to enhance empathy within their virtual Scrum teams.

Mental Models Of Translational Scientists, Rasnia Tabpla, Antonie J. Jetter

Engineering and Technology Management Faculty Publications and Presentations

Translational science aims to bridge the gap between scientific discoveries and practical application yet faces challenges in achieving high success rates. This study examines the effective engagement of translational scientists, who play a key role in the translation process. It uses Fuzzy Cognitive Maps (FCMs) to analyze the scientists' mental models and identify common concepts related to success factors, such as ability, resources, opportunity, and entrepreneurial competencies. It then compares the mental models of the scientists and finds that mental models exhibit similarities, yet variations exist such as density and connectedness. Scenario analysis with FCM is then used to identify …

Strengthening Capacity In Industrial Revolution 4.0 (Ir 4.0): A Case Study On Training Product-Service Systems Between The Us And Vietnam, Man Hang Yip, Ana Sofia Castellanos Santarnaria, Julia J. Babcock

Engineering and Technology Management Faculty Publications and Presentations

This case study analyzes how value is created in the development process of a collaborative training product-service system (PSS) designed for provincial government officials in Vietnam. This initiative, part of the USAID Strengthening Provincial Capacity (USAID SPC) project, encapsulates a series of training solutions designed to empower officials with key skills in engineering and technology management, including the knowledge to improve global value chains, upgrade technology infrastructure and sustainable production models. A primary driver for the “four-day course delivery”, the PSS analyzed in this study, was to bolster economic competitiveness at the provincial level in the context of Industrial Revolution …

Fatigue Performance Of 3d-Printed Poly-Lactic-Acid Bone Scaffolds With Triply Periodic Minimal Surface And Voronoi Pore Structures, Hamed Bakhtiari, Alireza Nouri, Majid Tolouei-Rad

Research outputs 2022 to 2026

Bone scaffolds serve a crucial role in tissue engineering, particularly in facilitating bone regeneration where natural repair is insufficient. Despite advancements in the fabrication of polymeric bone scaffolds, the challenge remains to optimize their mechanical resilience. Specifically, research on the fatigue behaviour of polymeric bone scaffolds is scarce. This study investigates the influence of pore architecture on the mechanical performance of poly-lactic-acid (PLA) scaffolds under quasi-static and cyclic compression. PLA scaffolds with a 60% porosity were fabricated using extrusion-based 3D printing in various designs: Gyroid, Lidinoid, Fischer–Koch, IWP, and Voronoi. Results demonstrated that Gyroid scaffolds had the highest compressive strength …

Slurry Infiltrated Low-Quality Construction And Demolition Coarse Aggregate Waste In Concrete - A Sustainable Construction, Vishnu Vijayan, Sanjay Kumar Shukla, K. M. Mini

Research outputs 2022 to 2026

Exponential growth in infrastructure projects, stimulated by emerging sophisticated technologies have been instrumental in the salutary proliferation of the construction sector, globally. An indubitable adversity of the rapid boom in the construction industry has been the rampant cumulative fallout of burgeoning waste during the demolition and construction phases of restoration. The current study explored the propriety of replacing natural coarse aggregate by low-quality recycled coarse aggregates (RCA) with varying proportions, along with silica fume (SF) and polypropylene (PP) fibers as admixtures, for the preparation of concrete. As the quality of RCA is determined by the history of its parent demolished …

Towards Load-Bearing Biomedical Titanium-Based Alloys: From Essential Requirements To Future Developments, Yu-Wei Cui, Liqiang Wang, Lai-Chang Zhang

Research outputs 2022 to 2026

The use of biomedical metallic materials in research and clinical applications has been an important focus and a significant area of interest, primarily owing to their role in enhancing human health and extending human lifespan. This article, particularly on titanium-based alloys, explores exceptional properties that can address bone health issues amid the growing challenges posed by an aging population. Although stainless steel, magnesium-based alloys, cobalt-based alloys, and other metallic materials are commonly employed in medical applications, limitations such as toxic elements, high elastic modulus, and rapid degradation rates limit their widespread biomedical applications. Therefore, titanium-based alloys have emerged as top-performing …

Dual Modification Of Reverse Osmosis Membranes With Nh2-Mil-125 And Functionalised Multiwalled Carbon Nanotubes For Enhanced Nanoplastic Removal, Javad Farahbakhsh, Mohadeseh Najafi, Mitra Golgoli, Seyedeh Zahra Haeri, Mehdi Khiadani, Amir Razmjou, Masoumeh Zargar

Research outputs 2022 to 2026

The present study describes a novel double-modified strategy for developing high-performance thin-film composite reverse osmosis (TFC-RO) membranes by incorporating titanium-based metal organic frameworks (NH2-MIL-125) and functionalised multiwalled carbon nanotubes (MWCNTs) into the support layer and selective layer, respectively. Initially, the support layer was subjected to successive modifications using NH2-MIL-125 mixed with polysulfone (PSF) in dimethylformamide DMF solution to investigate their impact on the performance and properties of the support layer and resultant TFC-RO membranes. Results indicated that the new structure of the modified support layer had significant influences on the developed TFC-RO membranes. Notably, the pristine PSF support exhibited a …

Recent Progress In Microencapsulation Technology And Its Applications In Petroleum Industry, Jingyi Zhu, Jiayu He, Jie Zhou, Zhaozhong Yang, Xiaogang Li, Ying Li, Zhenjiang You

Research outputs 2022 to 2026

Oilfield chemicals play a pivotal role in optimizing the development of oil and gas resources. Emerging technologies for the controlled release of these chemicals have captured considerable interest among petroleum engineers. Microencapsulation, a method widely employed for controlled release in various industries such as biotechnology, pharmaceuticals, and agriculture, is gaining traction in the realm of oil and gas exploitation. This paper provides a comprehensive review of encapsulation technologies, including solvent evaporation, coacervation, and polymerization methods. Special emphasis is placed on recent advancements in the applications of microcapsules within the oil and gas sector. Given the profound impact of release behavior …

Time-To-Failure Prediction Of Fine-Grained Soil Slopes Subject To Weather-Driven Deterioration, Arm M. Morsy

Mineta Transportation Institute

Embankments have been widely used in the construction of transportation and flood defense infrastructure. Embankments constructed from clays experience a suite of weather-driven deterioration processes that lead to a progressive loss of hydromechanical performance, causing potentially severe and costly consequences. This study aimed to predict the time to failure of aging, deteriorating clay embankments supporting transportation infrastructure. A multi-phase numerical modeling approach was developed to replicate the long-term, weather-driven, hydromechanical behavior of clay embankments. This model simulated the behavior of a number of well-documented embankment failure case studies that had sufficient data to derive the necessary soil properties and climate …

Moving Towards The Electrification Of Medium- And Heavy-Duty Vehicles In The Inland Empire, Kimberly Collins, Raffi Der Wartanian, Francisca Beer, Yunfei Hou

Mineta Transportation Institute

This report investigates the transition to zero-emission medium- and heavy-duty vehicles (MDHD) within California’s Inland Empire (IE), emphasizing the significance of electric vehicle charging infrastructure and opportunity charging strategies in facilitating sustainable transportation. Utilizing a mixed-methods approach that combines a systematic literature review, geospatial and big data analytics, and thematic analysis of expert interviews, the study explores the multifaceted challenges and opportunities of electrification. The literature review assesses policies at various governance levels, while geospatial analysis identifies regional traffic patterns and infrastructure needs. Big data analytics examine vehicle movements, complemented by insights from interviews with 16 regional experts, offering a …

Segac: Sample Efficient Generalized Actor Critic For The Stochastic On-Time Arrival Problem, Honglian Guo, Zhi He, Wenda Sheng, Zhiguang Cao, Yingjie Zhou, Weinan Gao

Research Collection School Of Computing and Information Systems

This paper studies the problem in transportation networks and introduces a novel reinforcement learning-based algorithm, namely. Different from almost all canonical sota solutions, which are usually computationally expensive and lack generalizability to unforeseen destination nodes, segac offers the following appealing characteristics. segac updates the ego vehicle’s navigation policy in a sample efficient manner, reduces the variance of both value network and policy network during training, and is automatically adaptive to new destinations. Furthermore, the pre-trained segac policy network enables its real-time decision-making ability within seconds, outperforming state-of-the-art sota algorithms in simulations across various transportation networks. We also successfully deploy segac …

Delineating Ground Subsidence And Flood Risk In Southeast Texas (Setx) Using Ps-Insar And Deep Learning, Arip Syaripudin Nur, Jinwoo An, Yong Je Kim

Civil Engineering Faculty Publications

This study investigates ground subsidence and its impact on flood risk in Southeast Texas (SETX), a region particularly susceptible to inundation due to rising sea levels and subsidence. Understanding subsidence patterns is crucial for geotechnical risk management and ground-use planning. Employing Persistent Scatterer Interferometry (PS-InSAR) with Sentinel-1 SAR data (2020-2023), the study delineates the spatiotemporal distribution of subsidence and its influence on flooding. PS-InSAR, wellsuited for urban areas, captures stable scatterers detected by SAR satellites, enabling detailed subsidence analysis. Time series analysis reveals subsidence evolution and its implications for flood risk management. Validation utilizes strategically placed GPS station data. Furthermore, …

Transient Heat Transfer To Rolling Or Sliding Drops On Inclined Heated Superhydrophobic Surfaces, Joseph Furner, Daniel Maynes, Brian D. Iverson, Julie Crockett

Faculty Publications

The thermal transport to drops that roll or slide down heated superhydrophobic surfaces is explored. High-speed infrared imaging is performed to provide time-resolved measurement of the heat transfer to the drop. Data are obtained for drops moving along smooth hydrophobic and structured superhydrophobic surfaces. Both post and rib style structures with surface solid fractions ranging from 0.06 to 1.0 are considered. The inclination angle of the surfaces was varied from 10 deg to 25 deg, and the drop volume was varied from 12 to 40 µL. The measurements reveal that the drop speed is a strong function of both the …

A Hierarchical Framework For Interpretable, Safe, And Specialised Deep Reinforcement Learning, Ammar Abbas

Doctoral

Safety-critical systems, which are crucial for human safety and the environment, are difficult to control and operate. Traditional controllers need precise models of these complex systems, which is hard to develop. \acrfull{drl} offers a potential solution by learning from interactions rather than detailed models, but it faces limitations such as non-transparent decision-making and an expensive, unsafe learning process. Additionally, a key challenge in DRL is ensuring effective decision-making in rare situations.

This thesis proposes a novel approach called the \acrfull{prop_frame} that enables safe and reliable control of critical systems. SRLA combines probabilistic modelling with reinforcement learning to create an interpretable …

Heat Treatment Post-Processing For The Improved Mechanical Properties Of Scalmalloy® Processed Via Directed Energy Deposition, Rachel Boillat-Newport, Sriram Praneeth Isanaka, Frank Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

As high-strength aluminum alloys present several processability issues with additive manufacturing (AM), Scalmalloy®, an Al-Mg-Sc-Zr-based alloy, has been developed. This alloy is age-hardenable, allowing it to precipitate out a strengthening precipitate phase, Al3(Sc,Zr). The manufacturer recommends a single-stage aging treatment at 325 °C for 4 h; however, the majority of the literature studies utilize a powder bed processing known as selective laser melting (SLM) over powder-fed processing directed energy deposition (DED). This study addresses the lack of information on heat treatments for DED fabrication by exploring the application of artificial aging temperatures of 300–400 °C for 2, 4, and 6 …

Enabling Sustainable Freight Forwarding Network Via Collaborative Games, Pang Jin Tan, Shih-Fen Cheng, Richard Chen

Research Collection School Of Computing and Information Systems

Freight forwarding plays a crucial role in facilitating global trade and logistics. However, as the freight forwarding market is extremely fragmented, freight forwarders often face the issue of not being able to fill the available shipping capacity. This recurrent issue motivates the creation of various freight forwarding networks that aim at exchanging capacities and demands so that the resource utilization of individual freight forwarders can be maximized. In this paper, we focus on how to design such a collaborative network based on collaborative game theory, with the Shapley value representing a fair scheme for profit sharing. Noting that the exact …

Influence Of Aggregate Properties On Skid Resistance Of Pavement Surface Treatments, Alireza Roshan, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Skid resistance is a critical aspect for traffic safety since it significantly influences vehicle control and minimizes the distance required for emergency braking. The surface characteristics of pavements play a pivotal role in determining skid resistance. To achieve the optimal skid resistance performance, the pavement must sustain a specific level of friction. Thus, it is advantageous to apply surface treatments in areas that require enhanced friction. This study investigates the impact of factors such as the aggregate source, size, morphological properties, and abrasion levels on the skid resistance and frictional characteristics of a high-friction surface treatment (HFST). A complete investigation …