Engineering Commons^™

Harnessing The Power Of Hollow Zein Nanoparticles For Enhanced Antifouling And Heavy Metal Removal Of Polyethersulfone Membranes, Farzan Esmali, Mohadeseh Najafi Arani, Elsie Betmoushoul, Masoumeh Zargar, Khalil Farhadi, Vahid Javan Kouzegaran, Rahim Molaei, Yaghoub Mansourpanah

Research outputs 2022 to 2026

This study explores the physicochemical characteristics of an innovative mixed matrix membrane made from polyethersulfone (PES) and hollow Zein nanoparticles (HZNs), which are derived from the corn storage protein, Zein. HZNs, with a mean diameter of 40 nm, were applied to address the challenges associated with metal and inorganic nanoparticles, such as their tendency to accumulate unevenly on the membrane surface. The membranes were fabricated by incorporating varying concentrations of HZNs into the PES casting solution through the nonsolvent phase separation method. The addition of HZNs enhanced the hydrophilicity and pure water flux of the membranes. It also modified the …

Real-Time Synthesis Of A Nonuniformly Correlated, Partially Coherent Beam Using An Optical Coordinate Tansformation, Milo W. Hyde Iv

Faculty Publications

We design, build, and validate an optical system for generating light beams with complex spatial coherence properties in real time. Beams of this type self-focus and are resistant to turbulence degradation, making them potentially useful in applications such as optical communications. We begin with a general theoretical analysis of our proposed design. Our approach starts by generating a Schell-model (uniformly correlated or shift-invariant) source by spatially filtering incoherent light. We then pass this light through an optical coordinate transformer, which converts the Schell-model source into a nonuniformly correlated field. After the general analysis, we discuss system engineering, including trade-offs among …

In Situ Assembly Enabling Adhesive-Free Bonding Of Large Area Electronic Sensors To Concrete For Structural Health Monitoring, Emmanuel Ogunniyi, Han Liu, Austin Downey, Simon Laflamme, Caroline Bennett, William Collins, Hongki Jo, Paul Ziehl

Faculty Publications

Cracks developed in concrete infrastructure are one of the primary mechanisms that degrade their structural integrity, which may result in structural failures. Previous research on soft elastomeric capacitors (SEC) has shown their viability for structural health monitoring of structural materials, including concrete, steel, and fiberglass composites. The SEC, or its derivative version with a corrugated geometry termed corrugated SEC or cSEC, is a parallel plate capacitor. Prior work demonstrated that it was possible to directly paint the electrode interfacing with the structural material onto the structure and adhere the rest of the pre-fabricated sensor onto the wet interface, thereby eliminating …

Overcoming Contamination Obstacles In Additive Manufacturing A Monolithic Propulsion Structure For The Sunrise Mission, Holly Walen, Emma Brown, Robert Fowler

Space Dynamics Laboratory Publications

The SunRISE propulsion system utilizes an additively manufactured monolithic structure containing a main tank, plenum, and six thrusters. The complex design geometry and novel manufacturing approach of this structure lends itself to several problems, primarily related to the consistent fabrication of the thruster channels. Standard cleaning methods for stereolithography printing were inadequate to meet program requirements for this structure, leading to the development of a rigorous cleaning approach and intermediate characterization of the thruster throughput during the manufacturing process. In this paper, we present the cleaning and characterization approach that lent to the successful manufacturing of the SunRISE propulsion structure.

Data Provenance Via Differential Auditing, Xin Mu, Ming Pang, Feida Zhu

Research Collection School Of Computing and Information Systems

With the rising awareness of data assets, data governance, which is to understand where data comes from, how it is collected, and how it is used, has been assuming evergrowing importance. One critical component of data governance gaining increasing attention is auditing machine learning models to determine if specific data has been used for training. Existing auditing techniques, like shadow auditing methods, have shown feasibility under specific conditions such as having access to label information and knowledge of training protocols. However, these conditions are often not met in most real-world applications. In this paper, we introduce a practical framework for …

Constrained Assortment Optimization Under The Cross-Nested Logit Model, Cuong Le, Tien Mai

Research Collection School Of Computing and Information Systems

We study the assortment optimization problem under general linear constraints, where the customer choice behavior is captured by the cross-nested logit model. In this problem, there is a set of products organized into multiple subsets (or nests), where each product can belong to more than one nest. The aim is to find an assortment to offer to customers so that the expected revenue is maximized. We show that, under the cross-nested logit model, the unconstrained assortment problem is NP-hard even when there are only two nests, and the problem is generally NP-hard to approximate to any constant factors. To tackle …

Brushbuds: Toothbrushing Tracking Using Earphone Imus, Qiang Yang, Yang Liu, Jake Stuchbury-Wass, Kayla-Jade Butkow, Dong Ma, Cecilia Mascolo

Research Collection School Of Computing and Information Systems

Inadequate toothbrushing habits are a leading cause of oral health problems such as tooth decay. Many individuals are uncertain if they are brushing effectively or over-focusing on specific areas. While high-end electric toothbrushes can address these concerns, manual toothbrushes remain widely used due to their simplicity and affordability. In this paper, we introduce BrushBuds, an earphone-based toothbrushing monitoring system aimed at tracking brushing areas, which leverages the ubiquitous presence of earphones to enhance manual toothbrushing. BrushBuds utilizes Inertial Measurement Units (IMUs) in earphones to detect subtle head movements incurred by toothbrushing. By capturing distinct motion patterns specific to brushing for …

A Comprehensive Study On Long-Term Durability Of Protective Epoxy Coatings For Electrified Roadways, Md Tareq Hassan, Samiul Alam, Juhyeong Lee

Mechanical and Aerospace Engineering Faculty Publications

Underground wireless power transmission (WPT) systems are susceptible to environmental threats such as high temperatures, water ingress, and mechanical impact from above-ground objects. Typical WPT systems electronics are safeguarded with civil-grade epoxy coating, thus it is imperative to assess the coating's durability in these extreme conditions. Among various environmental threats, this study is primarily focused on both experimental and numerical investigations on long-term water diffusion characteristics of civil-grade epoxy materials at various temperatures. A series of water diffusion tests were performed on the specimens made from two commercially available electronics casting epoxy materials at room (23°C) and high (50°C) temperatures. …

Bht-Qaoa: The Generalization Of Quantum Approximate Optimization Algorithm To Solve Arbitrary Boolean Problems As Hamiltonians, Ali Al-Bayaty, Marek Perkowski

Electrical and Computer Engineering Faculty Publications and Presentations

A new methodology is introduced to solve classical Boolean problems as Hamiltonians, using the quantum approximate optimization algorithm (QAOA). This methodology is termed the “Boolean-Hamiltonians Transform for QAOA” (BHT-QAOA). Because a great deal of research and studies are mainly focused on solving combinatorial optimization problems using QAOA, the BHTQAOA adds an additional capability to QAOA to find all optimized approximated solutions for Boolean problems, by transforming such problems from Boolean oracles (in different structures) into Phase oracles, and then into the Hamiltonians of QAOA. From such a transformation, we noticed that the total utilized numbers of qubits and quantum gates …

The Hydraulically Smooth Limit Of Flow Over Surfaces With Spanwise Heterogeneity, Haosen Xu, George Ilhwan Park, Xiang Yang, Xiaowei Zhu

Mechanical and Materials Engineering Faculty Publications and Presentations

Wall slip is conventionally obtained through riblets or grooves. As riblets are macroscopic objects, it is usually not practical to discuss slip patterns at the hydraulically smooth limit. Per Nikuradse, the smooth limit is when the characteristic length of the surface pattern is comparable to the viscous length scale. Recent studies show the possibility of slip at the microscopic scale, making slip patterns at the hydraulically smooth limit relevant. In this study, we leverage a high-fidelity pseudo-spectral code and study flow over surfaces featuring alternating strips of slip and no-slip wall conditions. The wavelength of the surface pattern, denoted as …

Characterization Of A Carbon Fiber Based Broadband Microwave Absorber, Ha Tran, Branimir Pejcinovic, Robert Doneker, Kent Thompson, Adithya Ramachandran

Electrical and Computer Engineering Faculty Publications and Presentations

This paper reports the development and characterization of a novel ultra-wideband microwave absorber material (MAM) based on vertically aligned carbon fibers and ferrite beads. This specific material combination and manufacturing process allows MAM design that is thin, lightweight, and broadband. The material is prepared using a flocking process in which its components are electrostatically deposited on top of an adhesive substrate. Distinct material properties of the substrate and materials layers require characterization done with two separated layers. The microwave absorption characteristics are studied first by rectangular waveguide measurements at X and Ku bands that yield complex electric permittivity and magnetic …

A Systems Biology Approach To Predict Phenotypes From Genotypes For Plants And Bacteria, Niaz Bahar Chowdhury

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

Predicting phenotypes from genotypes is a central challenge in systems biology in understanding how organisms respond to environmental and genetic changes. To address this, genome-scale metabolic models (GSMs) integrated with omics data and machine learning provide a comprehensive framework to connect genotype to phenotype. This dissertation utilizes these approaches in plants and bacterial systems, revealing key metabolic adaptations. In maize, a root-specific GSM reveals metabolic reprogramming under nitrogen stress, offering strategies for improving stress tolerance. Building on this, a multi-organ maize GSM of temperature stress identifies metabolic bottlenecks, providing targets to enhance crop resilience. Similarly, in rice, a grain-specific GSM …

Simultaneous Modulation Of Pulse Charge And Burst Period Elicits Two Differentiable Referred Sensations, T. R. Benigni, A. E. Pena, S. S. Kuntaegowdanahalli, J. J. Abbas, R. Jung

Biomedical Engineering Faculty Publications and Presentations

Objective. To investigate the feasibility of delivering multidimensional feedback using a single channel of peripheral nerve stimulation by complementing intensity percepts with flutter frequency percepts controlled by burst period modulation. Approach. Two dimensions of a distally referred sensation were provided simultaneously: intensity was conveyed by the modulation of the pulse charge rate inside short discrete periods of stimulation referred to as bursts and frequency was conveyed by the modulation of the period between bursts. For this approach to be feasible, intensity percepts must be perceived independently of frequency percepts. Two experiments investigated these interactions. A series of two alternative forced …

Effects Of Low-Cycle Fatigue Fracture Of Longitudinal Reinforcing Steel Bars On The Seismic Performance Of Reinforced Concrete Bridge Piers, Yu-Fu Ko, Jessica Gonzalez

Mineta Transportation Institute

Earthquakes, which can cause tremendous local stress and strain on infrastructure, can cause reinforced concrete (RC) bridges to collapse due to the concrete cracking and fracture of the steel reinforcement rebars. The fracture of longitudinal reinforcing steel due to low-cycle fatigue is one of the main causes of failure in RC structures under earthquake loading. The purpose of this research is to include the effects of low-cycle fatigue fracture of longitudinal reinforcing steel bars on the seismic performance of reinforced concrete bridge piers. To obtain a greater understanding of low-cycle fatigue failure of steel reinforcement of RC bridge piers subjected …

Ocapo: Fine-Grained Occupancy-Aware, Empirically-Driven Pdc Control In Open-Plan, Shared Workspaces, Ravi Anuradha, Dulaj Sanjaya Weerakoon, Archan Misra

Research Collection School Of Computing and Information Systems

Passive Displacement Cooling (PDC) is a relatively recent technology gaining attention as a means of significantly reducing building energy consumption overheads, especially in tropical climates. PDC eliminates the use of mechanical fans, instead using chilled-water heat exchangers to perform convective cooling. In this paper, we identify and characterize the impact of several key parameters affecting occupant comfort in a 1000m2 open-floor area (consisting of multiple zones) of a ZEB (Zero Energy Building) deployed with PDC units and tackle the problem of setting the temperature setpoint of the PDC units to assure occupant thermal comfort and yet conserve energy. We tackle …

Talar And Calcaneal Coordinate Axes Definitions Across Foot Pathologies, Kassidy Knutson, Erika P. Muhlrad, Andrew C. Peterson, Thomas Leonard, Abigail M. Anderson, Katelyn C. Aragon, Zachary J. Eatough, Bruce A. Macwilliams, Karen M. Kruger, Amy L. Lenz

Biomedical Engineering Faculty Research and Publications

The understanding of foot and ankle biomechanics is improving as new technology provides more detailed information about the motion of foot and ankle bones with biplane fluoroscopy, as well as the ability to analyze the hindfoot under weightbearing conditions with weightbearing computed tomography. Three-dimensional anatomical coordinate systems are necessary to describe the 3D alignment and kinematics of the foot and ankle. The lack of standard coordinate systems across research study sites can significantly alter experimental data analyses used for pre-surgical evaluation and post-operative outcome assessments. Clinical treatment paradigms are changing based on the expanding knowledge of complex pes planovalgus morphologies …

A Sophisticated Model Of Human Atherosclerosis On A Chip, Brandon J. Tefft

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Lumbar Spine Orientation Affects Compressive Fracture Outcome, Rachel Cutlan, Muhammaed Khokhar, Nader Shammout, Alok Shah, Lance Frazer, Narayan Yoganandan, Barry S. Shender, James Sheehy, Glenn Paskoff, Daniel Nicolella, Timothy B. Bentley, Saman Shabani, Brian D. Stemper

Biomedical Engineering Faculty Research and Publications

Purpose

Understanding how spinal orientation affects injury outcome is essential to understand lumbar injury biomechanics associated with high-rate vertical loading.

Methods

Whole-column human lumbar spines (T12–L5) were dynamically loaded using a drop tower to simulate peak axial forces associated with high-speed aircraft ejections and helicopter crashes. Spines were allowed to maintain natural lordotic curvature for loading, resulting in a range of orientations. Pre-test X-rays were used to quantify specimen orientation at the time of loading. Primary fracture types were identified (wedge, n = 6; burst, n = 4; hyperextension, n = 4) and compared for loading parameters and lumbar orientation. …

Realtime And Noninvasive Assessment Of Endotracheal Tube Displacement Using Near-Infrared And Visible Cameras, Tongtong Lu, Pawjai Khampang, Ahmed Beydoun, Rebecca Rodhe, Wenzhou Hong, Joseph E. Kerschner, Bing Yu

Biomedical Engineering Faculty Research and Publications

Endotracheal tube (ETT) intubation is a medical procedure routinely used for achieving mechanical ventilation in critically ill patients. Appropriate ETT placement is crucial as undetected tube migration may cause multiple complications or even fatalities. Therefore, prompt detection of unplanned movement of the ETT and immediate action to restore proper placement are essential to ensure patient safety. Despite this necessity, there is not a widely adopted tool for real-time assessment of ETT displacement. We have developed a device, a dual-camera endotracheal tube or DC-ETT, to address this unmet clinical need. This device uses a near-infrared (NIR) LED and a side-firing optical …

Rail Anchor Slip Force Testing, S. Mustapha Rahmaninezhad, Constantine Tarawneh, Arturo A. Fuentes, David Vera, Jorge Encinia

Civil Engineering Faculty Publications

Continuous welded rail (CWR) is increasingly adopted to replace jointed track due to its superior ride quality, extended fatigue life, and reduced maintenance costs. However, the absence of joints introduces challenges, such as thermal expansion-related track buckling. Maintaining the Rail Neutral Temperature (RNT) is essential for managing rail stresses and preventing these failures. Rail anchors are employed to distribute loads from rails to ties. The rail anchors enhance longitudinal track resistance by minimizing the rail’s longitudinal movement. These anchors are crucial for managing the RNT, ultimately contributing to the prevention of rail buckling and the reinforcement of the track structure. …

Mannosylated Pamam G2 Dendrimers Mediated Rate Programmed Delivery Of Efavirenz Target Hiv Viral Latency At Reservoirs, Rohini Kharwad, Mohsin Kazi, Nilesh Mahajan, Payal Badole, Sachin More, Asaad Kayali, Md Noushad Javed, Mohammed Kaleem

Mechanical Engineering Faculty Publications

In this current research, we conceptualized a novel nanotechnology-enabled synthesis approach of targeting HIV-harboring tissues via second-generation (G2) polyamidoamine (PAMAM) mannosylated (MPG2) dendrimers for programmed delivery of anti-HIV drugs efavirenz (EFV) and ritonavir (RTV). Briefly, here mannose served purpose of ligand in this EFV and RTV-loaded PAMAM G2 dendrimers, synthesized by divergent techniques, denoted as MPG2ER. The developed nanocarriers were characterized by different analytical tools FTIR, NMR, zeta potential, particle size, and surface morphology. The results of confocal microscopy showed substantial alterations in the morphology of H9 cells, favored by relatively higher drug uptake through the MPG2ER. Interestingly, the drug …

Experimental Study Of Coal Fines Migration Characteristics In Reservoirs With Diverse Coal Structures: Influence On Reservoir Behavior, Yingchun Wei, Ziliang Liu, Xianyue Xiong, Tiancheng Xie, Biao Li, Anmin Wang, Daiyong Cao, Zhenjiang You

Research outputs 2022 to 2026

The challenge of coal fines production within tectonic coal reservoirs during coalbed methane (CBM) development in China presents a significant concern. In this study, coal samples with distinct coal structures from Hancheng mining area were selected for experiments on coal fines migration. Our analysis focused on the distinctive characteristics of coal fines generated by various coal structures, the subsequent alterations in sample permeability, and the changes in pore and fracture structures before and after the experiments. By examining the reservoir properties across different structures, we aimed to uncover the migration characteristics of coal fines in these diverse coal reservoirs and …

Investigating Gender Bias In Large Language Models Through Text Generation, Shweta Soundararajan, Sarah Jane Delany

Conference papers

Large Language Models (LLMs) have swiftly become essential tools across diverse text generation applications. However, LLMs also raise significant ethical and societal concerns, particularly regarding potential gender biases in the text they produce. This study investigates the presence of gender bias in four LLMs: ChatGPT 3.5, ChatGPT 4, Llama 2 7B, and Llama 2 13B. By generating a gendered language dataset using these LLMs, focusing on sentences about men and women, we analyze the extent of gender bias in their outputs. Our evaluation is two-fold: we use the generated dataset to train a gender stereotype detection task and measure gender …

Impact-Free Gaits For Planar Bipeds: Changing Walking Speed And Gait, Aakash Khandelwal, Nilay Kant, Ranjan Mukherjee

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problems of changing the walking speed and stride length of impact-free gaits for point-foot planar bipeds are addressed. The impact-free gaits are designed using an approach developed in prior work. It is shown that the impulse controlled Poincaré map (ICPM) approach can be modified to transition between orbits defining gaits with different walking speeds, and the continuous controller can be changed during the swing phase to transition between gaits that have distinct stride lengths. The effectiveness of the approaches is demonstrated using simulations carried out on a five-link biped.

Iterative Correction Of Robotic Grinding Using Spatial Feedback For Precision Applications, Philip A. Olubodun, Joseph D. Fischer, Douglas A. Bristow

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Since the advent of robots, many tasks that were originally performed by humans have now been tasked to industrial robots. From a manufacturing standpoint, robots have primarily been used in pick-and-place or other non-machining operations that require high repeatability. However, with the increasing availability of CAD/CAM software and the development of high-precision metrology, comes the opportunity to integrate robots into a wider variety of manufacturing processes through the use of feedback control. One such machining operation that is being explored is precision grinding of metal parts. Most other work in this area has focused on force regulation to improve grind …

A Feedforward Kinematic Error Controller With An Angular Positioning Deviations Model For Backlash Compensation Of Industrial Robots, Mitchell R. Woodside, Tian Hao Cui, John Emelko, Soichi Ibaraki, Robert G. Landers, Douglas A. Bristow

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The accuracy of industrial robots, typically on the order of several millimeters, has inhibited their adoption in advanced aerospace manufacturing applications, such as robotic machining. For this reason, extensive investigations have been conducted to develop solutions to improve their accuracy. These solutions can be categorized into offline and online compensation strategies, both of which have advantages and limitations. Offline compensation has been shown to improve the accuracy of industrial robots by two to three orders of magnitude; however, the sensitivity of these solutions to environmental changes and external disturbances can degrade their performance. In contrast, online compensation, which utilizes real-time …

Wind Shear Induced Tornados With Full Thermodynamic Effects, Kakkattukuzhy M. Isaac

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Wind shear-induced Tornado behavior under full thermodynamic formulation using the ideal gas equation is investigated. The computational fluid dynamics model that includes the energy equation is used to obtain solutions of a natural-scale tornado under pressure and temperature boundary conditions that account for their variations vs. altitude in the atmosphere. The present results show significant differences from previous isothermal simulations and those using the Boussinesq model for buoyancy under small temperature differences. Results show that the downdraft observed in tornados originating from supercells, often accompanied by rain and hail can be captured using the present model that simulates the genesis, …

Performance Of Project Delivery Methods For Us Airport Projects: A Holistic Quantitative Risk-Based Assessment Through Perceptions Of Associated Industry Experts, Ramy Khalef, Islam H. El-Adaway

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The aviation sector received an underperforming D+ score, indicating its deteriorating qualities in comparison with the overall US infrastructure. In response, US governmental bodies issued investment bills that target the improvement of the nation's airport system. Airport projects are still being implemented through design-bid-build (DBB), which is notorious for its ineffective risk shift, low contractor input, and poor cost and schedule performance. Studies show that design-build (DB) possesses prospective cost and schedule benefits. Despite this, there is still reluctance toward DB's usage in airport projects. Moreover, current studies lack in offering frameworks that assist airport practitioners in guiding stakeholders toward …

Kinetic Modeling Of Dust Grain Dynamics In Electrostatic Sieving, Aaron Berkhoff, Easton Ingram, Fateme Rezaei, Jeffrey Smith, David Bayless, William Schonberg, Daoru Han

Chemical and Biochemical Engineering Faculty Research & Creative Works

A new kinetic particle modeling framework was developed to investigate electrostatic transport of lunar regolith dust particles with applications to the concept of electrostatic sieving. the new approach is based on kinetic particle dynamics and includes major modules of sampling the particle size distribution, solving electric fields, and tracking motion of charged dust grains. a case study for a concept of electrostatic sieving was chosen to validate the new model. the simulation achieved similar performance of particle size classification as reported in the literature. the new model is computationally efficient (takes a few minutes on a PC-type laptop computer) so …

Carboxymethyl Cellulose-Based Preformed Particle Gels For Water Management In Oil And Gas Reservoirs, Ahmed Ben Ali, Ahmed Hamza, Abdulaziz A. Almakimi, Mohammed Saad, Ibnelwaleed A. Hussein, Baojun Bai

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Carboxymethyl cellulose (CMC) based materials have been proposed as preformed particle gels (PPGs) for reducing excessive water production in oil and gas reservoirs. Multi-sized dry particles ranging between 100 and 1180 μm have been synthesized using microwave-assisted grafting copolymerization of CMC and acrylamide (AM)/n,n''-methylene-bisacrylamide (MBA). FTIR and SEM confirmed CMC crosslinked polyacrylamide's chemical structure and morphology (CMC/CPAM). Thermo-gravimetric analysis has demonstrated the thermal stability of dry PPGs up to 309 °C. CMC/CPAM showed slightly high absorbency in brine 2 (TDS = 67.3 g/L) compared to brine 1 (TDS = 33.65 g/L), 1% NaCl, and deionized water, with swelling ratios (SR) …