Engineering Commons^™

Vibrating Flexoelectric Micro-Beams As Angular Rate Sensors, Yilin Qu, Feng Jin, Jiashi S. Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We studied flexoelectrically excited/detected bending vibrations in perpendicular directions of a micro-beam spinning about its axis. A set of one-dimensional equations was derived and used in a theoretical analysis. It is shown that the Coriolis effect associated with the spin produces an electrical output proportional to the angular rate of the spin when it is small. Thus, the beam can be used as a gyroscope for angular rate sensing. Compared to conventional piezoelectric beam gyroscopes, the flexoelectric beam proposed and analyzed has a simpler structure.

Vibrating Flexoelectric Micro-Beams As Angular Rate Sensors, Yilin Qu, Feng Jin, Jiashi S. Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We studied flexoelectrically excited/detected bending vibrations in perpendicular directions of a micro-beam spinning about its axis. A set of one-dimensional equations was derived and used in a theoretical analysis. It is shown that the Coriolis effect associated with the spin produces an electrical output proportional to the angular rate of the spin when it is small. Thus, the beam can be used as a gyroscope for angular rate sensing. Compared to conventional piezoelectric beam gyroscopes, the flexoelectric beam proposed and analyzed has a simpler structure.

Geometric Analysis Of Insect Wing Vein Network, Jacob White, Ying Hu, Sangjin Ryu, Seunghee Kim, Haipeng Zhang

Department of Mechanical and Materials Engineering: Faculty Publications

An insect wing consists of a thin membrane supported by a system of veins, and flow of blood through the system of veins is critical for maintaining healthy insect wings. Better understanding of the insect wing vein circulation requires to know how the efficiency of blood flow in an insect wing relates to the geometric shape of the vein. Our investigation of the wing vein network of a dragonfly Anax junius follows the idea of Murray’s law, which is established in the study of efficiency of the vein network and the geometric shape of the vein. Instead of using the …

Femtosecond Laser Surface Processing To Create Self-Organized Micro- And Nano-Scale Features On Composite And Ceramic Materials, Nate Koeppe

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

Femtosecond laser surface processing (FLSP) is applied to a range of materials in this thesis. The materials studied were a carbon fiber reinforced polymer (CFRP), a thermosetting polymer, silicon nitride (Si₃N₄), and ceramic alumina. The CFRP is a composite material consisting of a thermosetting polymer and carbon fibers. The CFRP are referred to as a composite and the thermosetting polymer is referred to as a resin in this thesis. Alumina can exist in many different forms. The alumina used is 0.5 mm thick nonporous alumina sheets purchased from McMaster-Carr, and will be referred to as alumina …

A Novel Testbed For Evaluation Of Operational Technology Communications Protocols And Their On-Device Implementations, Matthew Boeding

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

Operational Technology (OT) and Infrastructure Technology (IT) systems are converging with the rapid addition of centralized remote management in OT systems. Previously air-gapped systems are now interconnected through the internet with application-specific protocols. This has led to systems that had limited access points being remotely accessible. In different OT sectors, legacy protocols previously transmitted over serial communication were updated to allow internet communication with legacy devices. New protocols such as IEC-61850 were also introduced for monitoring of different OT resources. The IEC-61850 standard’s Generic Object Oriented Substation Event (GOOSE) protocol outlines the representation and communication of a variety of different …

Production Of Polyhydroxybutyrate From Corn Fiber Using Paraburkholderia Sacchari, Twissa Mitra

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Poly(3-hydroxybutyrate) (PHB) is one of the most broadly studied members of the polyhydroxyalkanoates (PHA) family. It is a fully biodegradable thermoplastic produced by microbial fermentation having properties similar to polypropylene. PHB has a market price that is three times higher than the cost of synthetic plastics. Substrate cost makes up 50 to 60 % of that cost; hence, researchers have been exploring various cheap natural resources with high carbohydrate content to be used as a substrate for PHB production.

In this study, corn fiber, a lignocellulosic biomass has been studied as an option for a substrate to produce PHB. This …

Pesticide Application Management Toolset For Worker Protection Standards, Nathan W. Thorson

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

The application of Pesticides has become a widely adopted practice within modern agriculture, however this practice poses a significant health risk to farm workers and crop advisors when pesticide exposures occur. Current safety standards require documentation of each application to help mitigate human exposure, yet these standards rely heavily on antiquated data collection formats and complex communication systems putting little emphasis on notification timeliness. Our objective was to reduce the risk of pesticide exposure for all farm workers and crop advisors by utilizing technological automation processes to reduce the number of links within the communication system. This proved successful though …

Cybersecurity Of Agricultural Machinery: Exploring Cybersecurity Risks And Solutions For Secure Agricultural Machines, Mark Freyhof

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Modern agriculture is reliant on agricultural machinery for the production of food, fuel, and other agricultural products. The need for producing large quantities of quality agricultural products while sustainably stewarding environmental resources has led to the integration of numerous digital technologies into modern agricultural machinery, such as the CAN bus and telematic control units (Liu et al., 2021). An unintended drawback of these integrated digital technologies is the opportunity for these components to become cyberattack vectors. Cyberattack instances have increasingly targeted critical infrastructures, with numerous reports from agencies such as the Federal Bureau of Investigation (FBI) and Department of Homeland …

Study And Comparison Of The Performance Of Steel Frames With Brb And Sma Bracing, Mohsen Jalalvandi, Ahmad Soraghi, Seyed Mohammadreza Farooghi Mehr, Abbas Haghollahi, Ali Abasi

Department of Civil and Environmental Engineering: Faculty Publications

Designing steel structures with Concentric Braced Frame (CBF) lateral systems has been common in recent decades. This type of bracing has a quite unstable and complicated behavior in relatively intense earthquakes. This study tries to improve the seismic behavior of steel frames with CBF braces equipped with Shape Memory Alloy (SMA) and Buckling Restrained Braces (BRBs). In this manner, a multi-story building with inverted V chevron bracing was considered. Nonlinear time-history analyses have been performed using OpenSEES software. The dynamic responses of frames with SMA and BRB braces were compared. The results showed that the SMA and BRB braces provide …

Feature Analysis Of Indus Valley And Dravidian Language Scripts With Similarity Matrices, Sarat Sasank Barla, Sai Surya Sanjay Alamuru, Peter Revesz

School of Computing: Conference and Workshop Papers

This paper investigates the similarity between the Indus Valley script and the Kannada, Malayalam, Tamil, and Telugu scripts that are used to write Dravidian languages. The closeness of these scripts is determined by applying a feature analysis of each sign of these scripts and creating similarity matrices that describe the similarity of any pair of signs from two different scripts. The feature list that we use for the analysis of these Dravidian language-related scripts includes six new features beyond the thirteen features that were used for the study of Minoan Linear A and related scripts by Revesz. These new features …

Manufacturing And Characterization Of Continuous Nanofiber-Reinforced Composites, Lucas Barry

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

Fiber-reinforced composite laminates are some of the most advanced structural materials available. However, delamination remains a critical challenge due to its prevalence in structures and ability to cause catastrophic failure. Recently, high-temperature composites are at the forefront of polymer-matrix composites research, but they are prone to microcracking followed by delamination. Nanoreinforcement of interfaces by continuous nanofibers has been proposed earlier at UNL and produced increased interlaminar fracture resistance in conventional advanced composites. However, no studies have yet been conducted on emerging high-temperature composites. Also, there is insufficient information on the translatability of observed modes I and II interlaminar fracture toughness …

Studies On Air Injection In A Wastewater-Fed Subsurface Drip Irrigation System, Henry A. Gonzalez Hernandez

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

In 2020, the Ogallala High Plains Aquifer supplied irrigation water for approximately 3.6 million hectares in Nebraska, making it the most irrigated state in the United States. Although Nebraska is highly dependent in groundwater, locations included in the Gering-Fort Laramie Irrigation District (border of Nebraska and Wyoming) rely on surface water resources. In addition to these conventional water sources, using non-conventional alternatives for crop production can be just as important during water shortage times such as the one that e occurred in 2019 with the collapse of the Goshen/Gering-Fort Laramie Canal. Feedlot runoff presents a great opportunity in Nebraska, but …

Development Of A Decellularized Hydrogel Composite And Its Application In A Novel Model Of Disc-Associated Low Back Pain In Female Sprague Dawley Rats, David Lillyman

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Chronic low back pain is a global socioeconomic crisis compounded by an absence of reliable, curative treatments. The predominant pathology associated with chronic low back pain is degeneration of intervertebral discs in the lumbar spine. During degeneration, nerves can sprout into the intervertebral disc tissue and be chronically subjected to inflammatory and mechanical stimuli, resulting in pain. Pain arising from the intervertebral disc, or disc-associated pain, is a complex, multi-faceted disorder which necessitates valid animal models to screen therapeutics and study pathomechanisms of pain.

While many research teams have created animal models of disc degeneration, the translation of these platforms …

Efficiency Of Bank Filtration In The Removal Of Cyanotoxins Under Different Levels Of Nutrients, Luke Walkenhorst

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

Harmful Algal Blooms (HABs) are an increasing concern not only in Nebraska, but across the world. Increasing global temperatures in conjunction with overuse of synthetic fertilizers are leading causes to the increasing frequency and concern of HABs. In the present work, the effectiveness of simulated bank filtration (BF), as an economical water treatment option, to remove cyanotoxins under different levels of nutrients (nitrates and phosphates) was investigated. Vertical flow-through columns pre-acclimated with two levels of nutrients (e.g., nitrate and phosphate—10 vs. 50 mg/L) were exposed to two different levels of cyanotoxins (10 vs. 75 μg/L). Results from the study confirmed …

Simulating Sub-Threshold Communication Channels Through Neurons, Richard Maina

School of Computing: Dissertations, Theses, and Student Research

Molecular Communication is an emerging paradigm with the potential to revolutionize the technology behind wearable and implantable devices and the broad range of functions they support, from tracking physical activity to medical diagnostics. This can be achieved through intra-body communication networks that take advantage of natural biological processes as a means of transmitting, propagating and receiving information. In this thesis we focus particularly on using the neuron as a means to facilitate information transfer for interconnected wearable or implantable devices through a technique known as sub-threshold electrical stimulation. We develop upon a prior work by introducing a linear model of …

Understanding The Role Of Antioxidant Nanoparticles In Improving The Outcome Of Secondary Injury In Traumatic Brain Injury, Aria W. Tarudji

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Following traumatic brain injury (TBI), excess reactive oxygen species (ROS) and other free radicals are released, inducing the cascade of secondary injury that exacerbate the outcomes of TBI. Antioxidant nanoparticles (ANPs) have shown promising outcomes in reducing the progression of TBI, which may be due to the higher accumulation and retention of ANPs in the injured brain. However, there is limited knowledge of: 1) antioxidant activities needed in TBI treatment, 2) correlation between longer retention, bioavailability, and target engagement with antioxidant treatments, and 3) sexual dimorphism to ANP treatments.

This dissertation assesses multiple ANPs with various scavenging activities and durations …

Construction And Operation Of A Pilot-Scale Odor Control Device, Brendan Bunker

Department of Environmental Engineering: Theses and Other Student Research

Hydrogen sulfide (H₂S) is a naturally occurring by-product of anaerobic digestion and causes an odor that can be a nuisance and a public health risk at higher concentrations. This compound can be treated through various means, but one of particular interest is a biotrickling filter (BTF). Such devices have excellent H₂S treatment efficiencies, but start-up costs can be steep. The primary goal of this study is to explain the design and operation of a low-cost odor control device for improving environmental air quality in Nebraska using a BTF. This device has the potential for application as …

Development An Edge-Computing Sensing Unit For Continuous Measurement Of Canopy Cover Percentage Of Dry Edible Beans, Wei-Zhen Liang, Joseph Oboamah, Xin Qiao, Yufeng Ge, Robert M. Harveson, Daran R. Rudnick, Jun Wang, Haishun Yang, Angie Gradiz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Canopy cover (CC) is an important indicator for crop development. Currently, CC can be estimated indirectly by measuring leaf area index (LAI), using commercially available hand-held meters. However, it does not capture the dynamics of CC. Continuous CC monitoring is essential for dry edible beans production since it can affect crop water use, weed, and disease control. It also helps growers to closely monitor “yellowness”, or senescence of dry beans to decide proper irrigation cutoff to allow the crop to dry down for harvest. The goal of this study was to develop a device – CanopyCAM, containing software and hardware …

Effect Of Bromoform And Linseed Oil On Greenhouse Gas Emissions From Stored Beef Manure, Andrew Ortiz Balsero, Mara Zelt, Amy Millmier Schmidt, Miguel Fudolig, Daniel N. Miller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Emissions of carbon dioxide, methane, and nitrous oxide – potent greenhouse gases - from stored beef feedlot manure are a significant concern relative to climate change. Research on methane reduction strategies for enteric emissions has identified the application of organic additives, such as bromoform and linseed oil, to ruminant diets as potential solutions for reducing enteric emissions and pathogenic bacteria in excreted manure. The objective of this study was to determine the effect of bromoform and linseed oil on greenhouse gas emissions from beef feedlot manure, and on E. coli concentration in beef cattle manure, during a 5-week storage period. …

Combining Solution Reuse And Bound Tightening For Efficient Analysis Of Evolving Systems, Clay Stevens, Hamid Bagheri

School of Computing: Conference and Workshop Papers

Software engineers have long employed formal verification to ensure the safety and validity of their system designs. As the system changes—often via predictable, domain-specific operations—their models must also change, requiring system designers to repeatedly execute the same formal verification on similar system models. State-of-the-art formal verification techniques can be expensive at scale, the cost of which is multiplied by repeated analysis. This paper presents a novel analysis technique—implemented in a tool called SoRBoT—which can automatically determine domain-specific optimizations that can dramatically reduce the cost of repeatedly analyzing evolving systems. Different from all prior approaches, which focus on either tightening the …

Chemical Toxicants In Water: A Geohealth Perspective In The Context Of Climate Change, Naveen Joseph, Tate Libunao, Elizabeth Herrmann, Shannon L. Bartelt-Hunt, Catherine R. Propper, Jesse E. Bell, Alan S. Kolok

Department of Civil and Environmental Engineering: Faculty Publications

The editorial focuses on four major themes contextualized in a virtual GeoHealth workshop that occurred from June 14 to 16, 2021. Topics in that workshop included drinking water and chronic chemical exposure, environmental injustice, public health and drinking water policy, and the fate, transport, and human impact of aqueous contaminants in the context of climate change. The intent of the workshop was to further define the field of GeoHealth. This workshop emphasized on chemical toxicants that drive human health. The major calls for action emerged from the workshop include enhancing community engagement, advocating for equity and justice, and training …

Applications Of Stretching Technique And Time Window Effects On Ultrasonic Velocity Monitoring In Concrete, Bibo Zhong, Jinying Zhu

Department of Civil and Environmental Engineering: Faculty Publications

Coda wave interferometry (CWI) has been used to measure the relative wave-velocity change (dV/V) caused by small changes in materials. This study uses the stretching processing technique which has been used for CWI analysis to investigate velocity changes of direct longitudinal (P) wave, direct shear (S) wave, and coda wave in concrete by choosing different time windows of ultrasonic signals. It is found that the obtained wave-velocity change depends on the time window position, because the relative contribution of P wave and S wave is different in each signal window. This paper presents three experimental scenarios of velocity …

Octopus-Inspired Adhesive Skins For Intelligent And Rapidly Switchable Underwater Adhesion, Sean T. Frey, A. B. M. Tahidul Haque, Ravi Tutika, Elizabeth V. Krotz, Chanhong Lee, Cole B. Haverkamp, Eric J. Markvicka, Michael D. Bartlett

Department of Mechanical and Materials Engineering: Faculty Publications

The octopus couples controllable adhesives with intricately embedded sensing, processing, and control to manipulate underwater objects. Current synthetic adhesive–based manipulators are typically manually operated without sensing or control and can be slow to activate and release adhesion, which limits system-level manipulation. Here, we couple switchable, octopus-inspired adhesives with embedded sensing, processing, and control for robust underwater manipulation. Adhesion strength is switched over 450× from the ON to OFF state in <50 ms over many cycles with an actively controlled membrane. Systematic design of adhesive geometry enables adherence to nonideal surfaces with low preload and independent control of adhesive strength and adhesive toughness for strong and reliable attachment and easy release. Our bio-inspired nervous system detects objects and autonomously triggers the switchable adhesives. This is implemented into a wearable glove where an array of adhesives and sensors creates a biomimetic adhesive skin to manipulate diverse underwater objects.

Revealing Driver Psychophysiological Response To Emergency Braking In Distracted Driving Based On Field Experiments, Ying Li, Li Zhao, Kun Gao, Yisheng An, Jelena Andric

Department of Civil and Environmental Engineering: Faculty Publications

Purpose – The purpose of this paper is to characterize distracted driving by quantifying the response time and response intensity to an emergency stop using the driver’s physiological states.

Design/methodology/approach – Field tests with 17 participants were conducted in the connected and automated vehicle test field. All participants were required to prioritize their primary driving tasks while a secondary nondriving task was asked to be executed. Demographic data, vehicle trajectory data and various physiological data were recorded through a biosignalsplux signal data acquisition toolkit, such as electrocardiograph for heart rate, electromyography for muscle strength, electrodermal activity for skin conductance and …

A Pilot Study On The Nanoscale Properties Of Bone Tissue Near Lacunae In Fracturing Women, Wen Qian, Roman Schmidt, Joseph A. Turner, Sue P. Bare, Joan M. Lappe, Robert R. Recker, Mohammed P. Akhter

Department of Mechanical and Materials Engineering: Faculty Publications

The goal of this study is to investigate the causes of osteoporosis-related skeletal fragility in postmenopausal women. We hypothesize that bone fragility in these individuals is largely due to mineral, and/or intrinsic material properties in the osteocyte lacunar/peri-lacunar regions of bone tissue. Innovative measurements with nanoscale resolution, including scanning electron microscope (SEM), an atomic force microscope that is integrated with infrared spectroscopy (AFM-IR), and nanoindentation, were used to characterize osteocyte lacunar and peri-lacunar properties in bone biopsies from fracturing (Cases) and matched (Age, BMD), non-fracturing (Controls) postmenopausal healthy women. In the peri-lacunar space, the nanoindentation results show that the modulus …

Influence Of Aluminum Addition On The Laser Powder Bed Fusion Of Copper-Aluminum Mixtures, Nada Kraiem, Loic Constantin, A. Mao, Fei Wang, Bai Cui, Jean-François Silvain, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

The high optical reflectivity of copper (Cu) in the near infrared (NIR) domain and its elevated heat dissipation make Cu a challenging metal for laser powder bed fusion (LPBF), even with high energy densities (EDs). In this study, we demonstrated that adding aluminum (Al) powder by as little as 0.75, 1.5, and 3 wt.% substantially enhances Cu processability, leading to denser (up to 98%) and smoother (Ra = 3.3 𝜇m) Cu-Al parts as compared to 95% and 18 𝜇m, respectively, for the parts printed using pure Cu. In addition, this method reduces the ED required by a factor of two …

Microfluidic Device For Localized Electroporation, Justin Brooks, Arian Jaberi, Ruiguo Yang

Department of Mechanical and Materials Engineering: Faculty Publications

Electroporation is a common method of transfection due to its relatively low risk and high transfection efficiency. The most common method of electroporation is bulk electroporation which is easily performed on large quantities of cells yet results in variable levels of viability and transfection efficiency across the population. Localized electroporation is an alternative that can be administered on a similar scale but results in much more consistent with higher quality transfection and higher cell viability. This paper discusses the creation and use of a simple and cost-effective device using porous membrane for performing localized electroporation.

Phase Space Analysis Of Nonlinear Wave Propagation In A Bistable Mechanical Metamaterial With A Defect, Mohammed A. Mohammed, Piyush Grover

Department of Mechanical and Materials Engineering: Faculty Publications

We study the dynamics of solitary waves traveling in a one-dimensional chain of bistable elements in the presence of a local inhomogeneity (`defect'). Numerical simulations reveal that depending upon its initial speed, an incoming solitary wave can get transmitted, captured or reflected upon interaction with the defect. The dynamics are dominated by energy exchange between the wave and a breather mode localized at the defect. We derive a reduced-order two degree of freedom Hamiltonian model for wave-breather interaction, and analyze it using dynamical systems techniques. Lobe dynamics analysis reveals the fine structure of phase space that leads to the complicated …

Consemblex: A Consensus-Based Transcriptome Assembly Approach That Extends Consemble And Improves Transcriptome Assembly, Richard Mwaba

School of Computing: Dissertations, Theses, and Student Research

An accurate transcriptome is essential to understanding biological systems enabling omics analyses such as gene expression, gene discovery, and gene-regulatory network construction. However, assembling an accurate transcriptome is challenging, especially for organisms without adequate reference genomes or transcriptomes. While several methods for transcriptome assembly with different approaches exist, it is still difficult to establish the most accurate methods. This thesis explores the different transcriptome assembly methods and compares their performances using simulated benchmark transcriptomes with varying complexity. We also introduce ConSemblEX to improve a consensus-based ensemble transcriptome assembler, ConSemble, in three main areas: we provide the ability to use any …

Asymmetric Control Of Light At The Nanoscale, Christos Argyropoulos

Department of Electrical and Computer Engineering: Faculty Publications

Breaking reciprocity at the nanoscale can produce directional formation of images due to the asymmetric nonlinear optical response of subwavelength anisotropic resonators. The self-induced passive non-reciprocity has advantages compared to magnet or time modulation approaches and may impact both classical and quantum photonics.