Engineering Commons^™

Patterning Synthesis Of Lead Halide Perovskites Toward Photonic Application, S. M. Nayeem Arefin

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Lead halide perovskites (LHPs) are a fascinating class of photonic materials with the potential to revolutionize various optoelectronic applications. Their diverse crystal structures, ranging from 0D to 3D configurations, offer a unique combination of properties, including high tunability and ease of synthesis. However, their inherent instability and the difficulty of patterning them into sophisticated photonic structures using conventional methods present a significant hurdle to their widespread applications. This thesis addresses these challenges by proposing a novel synthesis method that combines soft lithography and self-assembly. By utilizing a patterned template with controlled wettability, precise manipulation of LHP crystal formation is achieved, …

Ultrashort Pulsed Laser Treatment Is Effective At Sterilizing Metal Surfaces For Planetary Protection, Kaleb Mcquillan

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

To prevent forward contamination from microbes aboard spacecraft intended for exploration of solar system bodies there is a need for effective sterilization methods. However, current techniques are both time-consuming and expensive. For example, dry heat sterilization requires removal from the assembly site and several days of treatment. Furthermore, some components such as optics and electronics are not compatible with current sterilization techniques. In this thesis, a novel femtosecond laser surface processing technique for the rapid sterilization of spacecraft hardware is reported. Femtosecond lasers produce extremely high photon fluxes (10²⁹ photons/s*cm², ~0.03 J/cm²) in extremely short …

Fabrication And Characterization Of Lignin–Pva Hydrogels With Tunable Network Structures, Keturah Bethel

All Dissertations

The ability to directly tune the crosslinked network structure of hydrogels is crucial for their functional applications in various fields, such as water filtration, protein separation, and tissue engineering. By controlling the crosslink density of the hydrogel, one can directly alter the mesh size – i.e., the end-to-end distance between crosslink junctions – and, subsequently, directly alter the hydrogel performance. This work discusses the fabrication and characterization of soft composites containing the biopolymer, lignin, are discussed. Precisely, physically-crosslinked composite lignin–Poly(vinyl alcohol) (PVA) hydrogels were fabricated via the freeze-thaw (F/T) pathway, whereby solutions containing specified amounts of PVA and lignin were …

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 …

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, …

Impacts Of High-Frequency Operation On Magnetics And Performance On Isolated Power Electronic Converter Design, David Arturo Porras Fernandez

Graduate Theses and Dissertations

The pursuit of high-power density and high switching frequency is a central theme in the advancement of power electronic converters. While these parameters offer significant benefits in terms of compactness and performance, they also introduce challenges related to efficiency and thermal management. This doctoral dissertation aims to provides a design framework to analyze the implications of high-frequency operation (> 100 kHz) on magnetics design and performance in power electronic converters, particularly when integrating silicon carbide (SiC) power modules. It examines the advantages and disadvantages of high-frequency operation and delves into its effects on the performance of the converter, focusing on …

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 …

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 …

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 …

Comparing Gas Composition From Fast Pyrolysis Of Live Foliage Measured In Bench-Scale And Fire-Scale Experiments, David R. Weise, Thomas H. Fletcher, Timothy J. Johnson, Wei Min Hao, Mark Dietenberger, Marko Princevac, Bret W. Butler, Sara S. Mcallister, Joseph J. O'Brien, E Louise Loudermilk, Roger D. Ottmar, Andrew T. Hudak, Akira Kato, Babak Shotorban, Shankar Mahalingham, Tanya L. Myers, Javier Palarea-Albaladejo, Stephen P. Baker

Faculty Publications

Background. Fire models have used pyrolysis data from oxidising and non-oxidising environments for flaming combustion. In wildland fires pyrolysis, flaming and smouldering combustion typically occur in an oxidising environment (the atmosphere). Aims. Using compositional data analysis methods, determine if the composition of pyrolysis gases measured in non-oxidising and ambient (oxidising) atmospheric conditions were similar. Methods. Permanent gases and tars were measured in a fuel-rich (non-oxidising) environment in a flat flame burner (FFB). Permanent and light hydrocarbon gases were measured for the same fuels heated by a fire flame in ambient atmospheric conditions (oxidising environment). Log-ratio balances of the measured gases …

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 …

Bioaffinity Analysis Of Aptamer-Target Interactions, Pooja Karunanithi

Honors Theses

This study explores the bioaffinity of aptamer-target interactions through a comprehensive analysis. Aptamers, oligonucleotides that can bind to target molecules, have emerged as powerful tools in various fields, including diagnostics and therapeutics. The primary objective of this research was to assess the binding affinity and specificity of selected aptamers to their respective targets using a combination of experimental techniques and computational models. The binding affinity of 10 different complexes were measured through surface plasmon resonance (SPR) followed by molecular simulations. The results showed that the 6th complex had the best binding affinity. The data suggest that these aptamers could be …

Integrating Building Information Modelling And Extended Reality In The Transportation Infrastructure Industry, Yosra El Maghraby, Shady Salem, Ahmed Alhady, Yasser Khodeir

Civil Engineering

No abstract provided.

Denoising And Super-Resolution Of In-Vitro 4e Flow Mri In A Stenotic Phantom Model Using Physics-Informed Neural Networks., Shrouk M. Wally

Electronic Theses and Dissertations

In recent years, the use of 4D flow MRI has revolutionized cardiovascular imag- ing by providing comprehensive data on blood flow dynamics over time. However, the limited spatial and temporal resolution of this imaging modality can hinder the accurate assessment of complex hemodynamic phenomena. This thesis explores the application of Physics-Informed Neural Networks (PINNs) to enhance the resolution of 4D flow MRI data, thereby improving its clinical utility. PINNs are a class of neural networks that integrate physical laws into their training process. By embedding these physics equations, PINNs can discover the underlying physics of fluid dynamics to produce more …

Novel Sensors, Algorithms And Metrics For Human-Robot Interaction., Henry Lee Reynolds

Electronic Theses and Dissertations

The increased presence and deployment of robotics in sectors such as the medical field results in the demand for robots to, directly and indirectly, interface with people and their environment, making human-robot interaction (HRI) a vital thrust of robotics research. Assistive robots, for example, aid humans in accomplishing tasks or by providing support in the workforce. As the demand for nurses and the aging population increases, the assistive robots deployed will be deeply rooted in environments that require constant interaction with humans. This work contributed to improving aspects of HRI through 1) Expanding accessibility of the methods used for interfacing …

Natural Language Processing For Automated Sysml Diagram Generation, Joshua Andre Ontiveros

Theses and Dissertations

This thesis explores the applications of natural language processing (NLP) techniques in model-based system engineering (MBSE) to help generate System Modeling Language (SysML) diagrams. MBSE is a method that aids in enhancing traditional engineering practices by modeling to help improve understanding and communication in systems development. SysML, one of the modeling languages for MBSE, helps represent a system's architecture, behavior, and information flow. Translating systems requirements and specifications into SysML models can be time-consuming and can lead to errors when created manually. Automating the creation of SysML diagrams from textual descriptions with the help of NLP techniques can aid in …

On The Right Track? Energy Use, Carbon Emissions, And Intensities Of World Rail Transportation, 1840–2020, Bernardo Tostes, Sofia T. Henriques, Paul E. Brockway, Matthew Kuperus Heun, Tiago Domingos, Tânia Sousa

University Faculty Publications and Creative Works

The history of rail transport can offer valuable insights for future energy transitions due to its importance in promoting clean mobility. There is a complex interplay between the evolution of the railway network, fuel consumption, efficiency, energy service, and CO2 emissions that requires further exploration. We developed a dataset that covers energy use in all stages of rail transportation, as well as the length of track, energy service, and CO2 emissions at the world scale. To deal with missing data we utilized machine learning techniques for the first time in a historical energy reconstruction study. Our analysis reveals that …

Modeling Study Of Si3N4 Waveguides On A Sapphire Platform For Photonic Integration Applications, Diandian Zhang, Shui-Qing Yu, Gregory J. Salamo, Richard A. Soref, Wei Du

Electrical Engineering and Computer Science Faculty Publications and Presentations

Sapphire has various applications in photonics due to its broadband transparency, high-contrast index, and chemical and physical stability. Photonics integration on the sapphire platform has been proposed, along with potentially high-performance lasers made of group III–V materials. In parallel with developing active devices for photonics integration applications, in this work, silicon nitride optical waveguides on a sapphire substrate were analyzed using the commercial software Comsol Multiphysics in a spectral window of 800~2400 nm, covering the operating wavelengths of III–V lasers, which could be monolithically or hybridly integrated on the same substrate. A high confinement factor of ~90% near the single-mode …

Engineered Nucleic-Acid Binding Intrinsically Disordered Proteins For Biomedical Applications, Telmo Diez Perez

Biomedical Engineering ETDs

This dissertation explores the use of intrinsically disorder proteins (IDPs) in biomedical applications related to the detection and biosensing of nucleic-acid species. We engineer several low critical solution temperature (LCST) nucleic-acid binding elastin-like polypeptides (ELPs) as model IDPs and study their potential in biomedical application via interactions with short single-stranded (ss) DNA, tRNA and viral RNAs. First, we engineer a simple polycationic ELP capable of recruiting DNA on demand in a DNA-protein-rich condensate via LLPS. Moreover, we develop a modified Flory-Huggins theory to quantify the partitioning of DNA and protein upon coacervate formation with and without salts. We then design …

Enhancing Thermal Stability Of Perovskite Solar Cells Through Thermal Transition And Thin Film Crystallization Engineering Of Polymeric Hole Transport Layers, Sanggyun Kim, Sina Sabury, Carlo A. R. Perini, Tareq Hossain, Augustine O. Yusuf, Xiangyu Xiao, Ruipeng Li, Kenneth R. Graham, John R. Reynolds, Juan-Pablo Correa-Baena

Chemical and Materials Engineering Faculty Publications

Organic hole transport layers (HTLs) have been known to be susceptible to thermal stress, leading to poor long- term stability in perovskite solar cells (PSCs). We synthesized three 2,5-dialkoxy-substituted, 1,4-bis(2-thienyl)phenylene (TPT)-based conjugated polymers (CPs) linked with thiophene-based (thiophene (T) and thienothiophene (TT)) comonomers and evaluated them as HTLs in n-i-p PSCs. TPT-T (MB/C6), which has branched 2- methylbutyl and linear hexyl (MB/C6) side chains, emerged as a promising HTL candidate, enabling power conversion efficiencies (PCEs) greater than 15%. In addition, PSCs with this HTL showed an improvement in long-term stability at elevated temperatures of 65 °C when compared to those …

Data Files For Optical Imaging Provides Flowcytometry-Like Single Cell Level Analysis Of Hif-1Α Mediated Metabolic Changes In Radio-Resistant Head And Neck Squamous Carcinoma Cells, Jing Yan, Carlos Frederico Lima Goncalves, Pranto Soumik Saha, Cristina M. Furdui, Caigang Zhu

Biomedical Engineering Faculty Publications

No abstract provided.

Simulation Modeling Of An Earth Entry System And Solar Radiation Pressure Module Development, Michael Sean Manwell

Mechanical & Aerospace Doctoral and Master's Level Projects and Papers

Several trajectory simulation tools are used to model different phases of the Approach, Entry, Descent and Landing (AEDL) phase of NASA’s Mars Sample Return Campaign. Working towards a single simulation tool that models all AEDL phases, this project utilizes Program to Optimize Simulated Trajectories II to simulate the 72-hour exoatmospheric phase of AEDL up till the point of Earth atmospheric entry. This involves developing a new feature for POST2 that captures the forces and moments caused by solar radiation pressure (SRP). Generalizing the vehicle geometry as a combination of primitive shapes, a generalized SRP module was created and implemented into …

Determination Of Binary Co2/H2 Adsorption Isotherms And Kinetics Over Porous Organic Cage Cc3 Via Zero-Length Column Technique, Jimmy D.L. Moreno, Kyle Newport, Ali A. Rownaghi, Fateme Rezaei

Chemical and Biochemical Engineering Faculty Research & Creative Works

Understanding the dynamics of mixed-gas adsorption is essential for industrial-scale adsorptive separations. Also, obtaining binary adsorption isotherms is essential to gain a better understanding of adsorbate-adsorbent interactions in multicomponent gas mixtures. Porous organic cages (POCs) are highly porous, crystalline materials, with a small average pore window that make them promising candidates for separation applications. In this work, we utilized zero-length column (ZLC) technique to not only determine the kinetics of CO₂/H₂ separation over CC3 but also obtain the binary adsorption isotherms. The ultra crystalline diffusivities of 1.49 x 10^–4 and 8.31 x 10^–5 cm^{2 …}

Carbon Capture And Renewable Energy Policies: Could Policy Harmonization Be A Puzzle Piece To Solve The Electricity Crisis?, Mahelet G. Fikru, Fateh Belaïd, Hongyan Ma

Economics Faculty Research & Creative Works

The electricity market crisis, driven by factors such as increased energy demand, rising fuel prices, aging infrastructure, and greenhouse gas emissions, requires a multifaceted approach including the strategic implementation of Carbon Capture and Storage (CCS) technologies, which despite high costs and potential adverse impact on renewable investments, can allow the use of fossil fuels to maintain grid stability, and simultaneously lower carbon footprint. Across the world, several nations are designing financial incentives and improving regulatory frameworks to reduce barriers to the deployment of CCS. However, it is not clearly understood whether and to what extent such policy support would affect …

Synthesis Of Selenium Nanostructures: Rods, Wires, And Fibers By Pulsed Laser Ablation In Liquids, Atikur Rahman

Theses and Dissertations

Selenium is a semiconductor that has a bulk energy bandgap of 1.74 eV, is mainly used in sensors, rectifiers, and advanced photovoltaic solar cells. Selenium is very important for the energy applications and was declared as Energy Critical Element (ECE) by the American Physical Society (APS) and the Materials Research Society (MRS). The goal of this dissertation was to control the growth of selenium when being irradiated by a pulsed laser within a liquid environment. The method called “Pulsed Laser Ablation in Liquids” is a green synthesis technique that allows for ligand-free nanoparticles to be created. Laser repetition rates were …

Development Of An Egg-Specific Mass Spectrometry Targeted Method For Processed Food Matrices, Liyun Zhang

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

Egg is a major food allergen in the United States, causing symptoms from mild reactions to severe anaphylaxis. An egg-free diet remains the only management approach for egg allergy. Therefore, individuals and families living with egg allergies rely heavily on allergen statements on packaged food products for informed food choices. Currently, no labeling regulations exist for unintentionally introduced allergens, posing risks to consumers with egg allergies. Therefore, it is critical to have an accurate and reliable detection method in allergen control and management to determine the concentration of total protein from allergenic food sources. Traditional enzyme-linked immunosorbent assays are routinely …

Development Of Feature Extraction Models To Improve Image Analysis Applications In Cancer, Yu Shi

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

Cancer poses a significant global health challenge. With an estimated 20 million new cases diagnosed worldwide in 2022 and 9.7 million fatalities attributable to the disease, the economic burden of cancer is immense. It impacts healthcare systems and imposes substantial costs for its care on patients and their families. Despite advancements in early detection, prevention, and treatment that have reduced overall cancer mortality rates, the growing prevalence of cancer, particularly among younger individuals, remains a pressing issue.

Recent advancements in medical imaging technology have progressed significantly with the help of emerging computer vision and artificial intelligence (AI) technology. Despite these …

Investigation Of Faults In Air-Conditioning Systems In Commercial Buildings: Occurrence, Diagnostic Validation, And Energy Impacts, Yuxuan Chen

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

In commercial buildings, fault detection and diagnosis (FDD) tools have been developed for detecting and diagnosing faults in building systems, which can provide useful information regarding fault locations and potential causes of faults, so that building operators and facility staff can be notified in time and quickly respond as problems arise. Nowadays, there are many commercial FDD tools available in the market, and these tools have been widely adopted in large- and medium-scale commercial buildings in the United States. Several studies have demonstrated the energy saving potential with the use of FDD in commercial HVAC systems, and one critical aspect …

Long Term Ultrasonic Monitoring And Machine Learning Investigation Of Micro-Crack Damaged Concrete, Yalei Tang

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

The thermal modulation method is a recently developed nonlinear ultrasonic technique for evaluating material damage. This method utilizes thermal strain changes resulting from temperature variations to excite the nonlinear behavior of materials and modulate high-frequency ultrasonic waves within them. Its working principle suggests significant potential for application in large-scale concrete structures and in-situ monitoring of real structures. Despite numerous laboratory demonstrations of its effectiveness, several gaps remain before it can be applied to in-service large concrete structures.

This study investigates the potential of the thermal modulation technique for evaluating concrete structures in ambient conditions, addressing key uncertainties for practical implementation. …