Engineering Commons^™

Development And Characterization Of A Decellularized Neuroinhibitory Scaffold Containing Matrix Bound Nanovesicles, Logan Piening

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

Chronic low back pain (LBP) is a leading cause of disability but treatments for LBP are limited. Degeneration of the intervertebral disc leads to loss of neuroinhibitory sulfated glycosaminoglycans (sGAGs) which allows nerves from dorsal root ganglia (DRG) to grow into the core of the disc, leading to pain. Current treatments for LBP involve drugs that do not target the source of the pain and lack long term efficacy or use invasive surgeries with high complication rates. Treatment with a decellularized tissue scaffold that contains neuroinhibitory components may inhibit nerve growth and prevent disc-associated LBP. Here, a decellularized nucleus pulposus …

Low-Noise, Low-Power Analog Front End For Dual Detector, Event-Driven Radioactive Isotope Identification, Joseph Medinger

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

An analog front end (AFE) design for a low-noise, low-power, event-driven radioactive spectroscopy system is implemented in a 65 nm CMOS technology. The AFE is optimized for use with two scintillation based detectors, CsI(Na) and LaBr3(Ce), that utilize photo-multiplier tubes for charge amplification. The amplification within the AFE is accomplished through charge sensitive amplifier designs that are tailored to each detector type. The AFE includes adjustable bias generation circuits to allow amplifier tuning for process, voltage, and temperature variations. The presented AFE is implemented along with analog to digital acquisition circuits and a microcontroller to provide a single-chip radioactive spectroscopy …

Semantically Meaningful Sentence Embeddings, Rojina Deuja

School of Computing: Dissertations, Theses, and Student Research

Text embedding is an approach used in Natural Language Processing (NLP) to represent words, phrases, sentences, and documents. It is the process of obtaining numeric representations of text to feed into machine learning models as vectors (arrays of numbers). One of the biggest challenges in text embedding is representing longer text segments like sentences. These representations should capture the meaning of the segment and the semantic relationship between its constituents. Such representations are known as semantically meaningful embeddings. In this thesis, we seek to improve upon the quality of sentence embeddings that capture semantic information.

The current state-of-the-art models are …

Complete Modeling Of The Chondrogenic Environment Under Continuous Low-Intensity Ultrasound, Heather Newell

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Articular cartilage is an avascular tissue that requires therapeutic intervention methods. This work answers the following: determine transducer operation to optimize the bioeffects; calculate the magnitude of pressure exerted on chondrocytes at an injury site; and confirm the theoretical findings by an animal model.

Earlier work has shown that cellular response to US is maximized at the resonance frequency of the cells. Resonance frequencies were calculated for chondrocytes in various layers. The latter configuration closest resembles in vivo conditions and the resonance occurred at 3.8±0.3 ������. The 3D model of US propagation in a rabbit knee was constructed from MRIs …

Genome Annotation Using Average Mutual Information, Garin P. Newcomb

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

Advancements in high-throughput DNA sequencing technologies and ambitious goals for their use are resulting in the generation of a deluge of unannotated sequenced genomes. This makes computational tools that can aid in annotation increasingly valuable.

Here, we provide a detailed exploration of the utility as well as the limitations of average mutual information (AMI) in several steps of genome annotation. For a genomic sequence, AMI is a measure of the information a base contains about the base separated by a fixed lag. A profile is constructed by calculating AMI at multiple lags. In addition to traditional AMI, we employ two …

Risk-Based Machine Learning Approaches For Probabilistic Transient Stability, Umair Shahzad

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

Power systems are getting more complex than ever and are consequently operating close to their limit of stability. Moreover, with the increasing demand of renewable wind generation, and the requirement to maintain a secure power system, the importance of transient stability cannot be overestimated. Considering its significance in power system security, it is important to propose a different approach for enhancing the transient stability, considering uncertainties. Current deterministic industry practices of transient stability assessment ignore the probabilistic nature of variables (fault type, fault location, fault clearing time, etc.). These approaches typically provide a conservative criterion and can result in expensive …

Detecting And Evaluating Cracks On Aging Concrete Members With Deep Convolutional Neural Networks, Brendan Barnes

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

Cracks in concrete structures are evaluated through a timely and subjective manual inspection. The location of cracks is often recorded in an inspection report where some cracks are measured. Although measurements or locations may not be necessary for all cracks observed in concrete members, if quantitative data can be gathered in an autonomous way, allowing measurement data to be used in tracking changes in spatial and temporal scales, this quantitative data can provide useful information not yet captured in the manual inspection process. This thesis aims to construct an image-based crack detection and evaluation pipeline that can assist health monitoring …

Comparative Analysis Of Kmer Counting And Estimation Tools, Ankitha Vejandla

School of Computing: Dissertations, Theses, and Student Research

The rapid development of next-generation sequencing (NGS) technologies for determining the sequence of DNA has revolutionized genome research in recent years. De novo assemblers are the most commonly used tools to perform genome assembly. Most of the assemblers use de Bruijn graphs that break the sequenced reads into smaller sequences (sub-strings), called kmers, where k denotes the length of the sub-strings. The kmer counting and analysis of kmer frequency distribution are important in genome assembly. The main goal of this research is to provide a detailed analysis of the performance of different kmer counting and estimation tools that are currently …

Measuring Foundation Course Modulus Using Falling Weight Deflectometer, Light Weight Deflectometer, And Dynamic Cone Penetration, Bruce Barrett, Kellie Troxel, Brady Dresselhaus, David Hansen

Nebraska Department of Transportation: Research Reports

Phase I results showed that FWD, LWD, and DCP provided valid results and trended with each other at the stations all three tests were run. This gives confidence that any test method is reliable when used on an exposed bituminous foundation course.

The results of Phase I and Phase II indicate that using FWD testing after concrete is built does not provide an accurate modulus of the foundation course. As demonstrated through the statistical analysis, foundation course moduli cannot be reliably calculated by using FWD on top of doweled concrete pavements and back-calculated using Darwin software or ME Design. Additionally, …

Formation Of B Horizons In Engineered Putting Green Soils, Glen R. Obear

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Engineered turfgrass putting green soils are designed to drain quickly, while maintaining adequate water- and nutrient-holding capacity to sustain plant growth. These soils are designed to meet specific performance characteristics when they are constructed, but the process of soil formation changes these characteristics over time. Chapter 1 of this dissertation is a literature review of soil formation in engineered putting green soils. Pedogenesis of putting greens is such that A horizons form as organic matter accumulates near the surface, and B horizons form as particles and solutes are translocated to textural or pH boundaries in soil profiles. In the engineered …

Measuring Foundation Course Modulus Using Falling Weight Deflectometer, Light Weight Deflectometer, And Dynamic Cone Penetration, Bruce Barrett, Kellie Troxel, Brady Dresselhaus, David Hansen

Nebraska Department of Transportation: Research Reports

The purpose of this investigation was to determine the feasibility of measuring bituminous foundation course modulus under concrete roadways by comparing testing results derived before and after paving using FWD, Light Weight Deflectometer (LWD), and Dynamic Cone Penetrometer (DCP). The foundation course modulus was determined using FWD data and Darwin design software (‘93 AASHTO). Results from Phase I data collection, which occurred prior to pavement placement, provided a baseline for comparison. The maximum modulus was 398,000 PSI and the minimum was 85,000 PSI, yielding a range of 315,000 PSI and an average modulus of 123,000 PSI over the length of …

Evaluation Of A Novel Approach For Assessing Biological Activity In Agricultural Soils, Karla Melgar

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

Soil health is a key factor impacting soil resilience and fertility in crop production systems. Favorable soil physical and biological conditions facilitate plant nutrient absorption and nutrient cycling. Demonstrating to farmers the impacts and changes in soil biological activity under different soil management practices has been a challenge due to the limited availability of inexpensive tools for quantifying this component of soil health. The primary goal of this study was to present a simple and readily accessible tool for evaluating soil biological activity to promote the use of organic amendments in crop fields. Research plots were established in two studies …

High-Frequency Unmanned Aircraft Flights For Crop Canopy Imaging During Diurnal Moisture Stress, Suresh Pradhyun Kashyap

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

Previous research has used unmanned aerial vehicle (UAV) technology for calculating CWSI (Crop Water Stress Index) values in the context of irrigation scheduling. Typically, these estimations were taken at one time of day, usually near shortly after solar noon. A significant limitation with these CWSI values is that the UAV thermal imagery captured at this point in time can be affected by various factors like atmospheric air temperature, solar radiation, wind speed, relative humidity, and other micrometeorological disturbances in the air. In order to address these temporal effects, high-frequency UAV flights were conducted over different daylight hours to analyze and …

Preferential Flow In Riparian Buffers: Current Research And Future Needs., Derek M. Heeren, Lucie Guertault, Kyle Mankin

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Preferential flow in riparian buffers can substantially compromise their effectiveness in reducing contaminants from overland runoff. The objective of this article is to introduce a collection of five articles on current research into subsurface preferential flow measurement, visualization, modeling, and impacts on contaminant fate and transport at scales ranging from the subsurface pore scale to the plot scale to the watershed scale. This collection presents selected works from a broader invited session on “Preferential flow and piping in riparian buffers” at the 2020 ASABE Annual International Meeting. Major findings include: new methodologies, such as light transmission and geophysics, to characterize …

Sprinkler Irrigation System Field Checklist, Charles C. Hillyer, R. Troy Peters, Xin Qiao, Derek M. Heeren, Jake Larue, Clarence Prestwich, Sandeep Bhatti

Department of Agricultural and Biological Systems Engineering: Faculty Publications

This recommendation came out of a noted need by the ASABE NRES-241 sprinkler irrigation committee in 2019 committee meeting for a simple checklist to quickly educate new center pivot operators on what to look for to determine if a center pivot is operating at designed performance. This checklist is meant to be simple and user friendly. Simple and clear language was incorporated purposefully. It is intended as a quick guide to new irrigators, or as a reminder to more experienced irrigators as to what to check to ensure efficient and effective center pivot and linear move irrigation system operation for …

Corn Fiber As A Biomass Feedstock For Production Of Succinic Acid, Lisbeth Vallecilla-Yepez, Divya Ramchandran, Dianna Long, Rajib Saha, Mark R. Wilkins

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The selection of an economical carbon source is a fundamental parameter to establish a successful industrial succinic acid (SA) bioprocess. In this work, corn fiber (CF), a renewable and an inexpensive source of carbohydrates, was successfully used for bioproduction of SA. Optimized liquid hot water (LHW) pretreatment followed by enzymatic hydrolysis were used to obtain corn fiber hydrolysate (CFH). Results in batch fermentation with Actinobacillus succinogenes showed that a control solution mimicking CFH produced 28.7 g/L of SA with a yield of 0.67 g SA/g sugars, while fermentation of CFH produced 27.8 g/L of SA with a yield of 0.61 …

Application Of Biochar As Beneficial Additive In Concrete, Temirlan Barissov

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

Biochar is a high-carbon solid material produced via thermal decomposition of organic biomass in a low-oxygen environment. Characterized with high water retention properties and high alkalinity, biochar is generally used for soil amendment and fertilization purposes. This study is intended to explore the feasibility of using biochar as a beneficial additive of the most used manmade material, concrete. Literature review revealed several studies where biochar was successfully implemented as an additive in concrete. The beneficial influence of biochar on the mechanical characteristics of concrete is based on nucleation and densification effects. However, the internal microstructure, porosity and chemical composition of …

Modeling Watershed Sensitivity To Climate Change In Systems Affected By Discharge Of Mine Tailings, Johnette C. Shockley

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

For more than a century, a large volume of gold-mining tailings was deposited in Whitewood Creek and the Belle Fourche River, tributaries to the Cheyenne River in western South Dakota. Much of it still remains, and field and historical evidence indicates continued remobilization of tailings-containing alluvium in these bedrock-dominated channels. Both long-term, natural fluctuations in climate and anthropogenically driven changes can impact regional precipitation, temperature, hydrologic patterns, and ecosystem functions. Such changes have the potential to affect both the transport and distribution of arsenic-laden sediments and mechanical erosion that can undermine the stability of channel-bed and overbank material.

This study …

Novel Peridynamic Models For Material Degradation And Mass Transport, Jiangming Zhao

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

Fracture and corrosion are two major causes of structure failure. They can interact with each other, leading to faster material degradation. They are also under the influence of environmental conditions. The corrosion rate highly depends on the transportation rate of involving substances, while the fracture can be accelerated significantly due to fluid flow. These complex mechanisms involved in structure failure have troubled classical models for decades. The peridynamic (PD) theory introduced in 2000 has shown great potential in modeling such problems. In this work, we develop novel PD models for fracture, corrosion, mass transport, and viscous flow, which are building …

Design And Evaluation Of Unmanned Aerial System-Based Wireless Sensor Network For Irrigation Management, Jasreman Singh

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

Increasing pressure on food production, both in terms of quantity and quality, has called for intensification and modernization of the agricultural sector. The “Internet of Things” (IoT) is a highly promising technology capable of advancing agricultural operations. The IoT-based real-time monitoring of soil water status and crop canopy temperature in maize and soybean could potentially improve irrigation efficiency, leading to the profitability of field crop production and conservation of natural resources. The overall goal of the work presented here is to design, develop, and evaluate the unmanned aerial system-based wireless sensor system (UWSN) for the purpose of irrigation management by …

Multilayer Lateral Heterostructures Of Van Der Waals Crystals With Sharp, Carrier–Transparent Interfaces, Eli A. Sutter, Raymond R. Unocic, Juan-Carlos Idrobo, Peter Sutter

Department of Electrical and Computer Engineering: Faculty Publications

Research on engineered materials that integrate different 2D crystals has largely focused on two prototypical heterostructures: Vertical van der Waals stacks and lateral heterostructures of covalently stitched monolayers. Extending lateral integration to few layer or even multilayer van der Waals crystals could enable architectures that combine the superior light absorption and photonic properties of thicker crystals with close proximity to interfaces and efficient carrier separation within the layers, potentially benefiting applications such as photovoltaics. Here, the realization of multilayer heterstructures of the van der Waals semiconductors SnS and GeS with lateral interfaces spanning up to several hundred individual layers is …

Quick - Release End Effector Tool Interface, Shane Farritor, Thomas Frederick

Department of Mechanical and Materials Engineering: Faculty Publications

The various embodiments herein relate to a coupling apparatus for a medical device having a coupler body, a cavity defined in the coupler body, a rotatable drive component disposed within the cavity and having at least two pin receiving openings, and an actuable locking ring disposed around the cavity.

Cybert: Cybersecurity Claim Classification By Fine-Tuning The Bert Language Model, Kimia Ameri, Michael Hempel, Hamid Sharif, Juan Lopez Jr., Kalyan Perumalla

Department of Electrical and Computer Engineering: Faculty Publications

We introduce CyBERT, a cybersecurity feature claims classifier based on bidirectional encoder representations from transformers and a key component in our semi-automated cybersecurity vetting for industrial control systems (ICS). To train CyBERT, we created a corpus of labeled sequences from ICS device documentation collected across a wide range of vendors and devices. This corpus provides the foundation for fine-tuning BERT’s language model, including a prediction-guided relabeling process. We propose an approach to obtain optimal hyperparameters, including the learning rate, the number of dense layers, and their configuration, to increase the accuracy of our classifier. Fine-tuning all hyperparameters of the resulting …

Higher Sound Levels In K-12 Classrooms Correlate To Lower Math Achievement Scores, Laura Caroline Brill, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Sound levels from occupied classrooms have been gathered from 220 classrooms across four grade levels (3, 5, 8 and 11) over six school days each and processed with k-means clustering into speech and non-speech clusters. Three metrics describing the classroom acoustics, including the average daily A-weighted equivalent level for non-speech, the average daily difference between the A-weighted equivalent levels for speech and nonspeech (a signal to noise ratio), and the mid-frequency averaged reverberation time, were analyzed against classroom-aggregated standardized reading and math achievement test scores, while controlling for classroom demographics including socioeconomic status. Interactions between the metrics and demographics were …

Investigation Of The Prevalence Of Faults In The Heating, Ventilation, And Air-Conditioning Systems Of Commercial Buildings, Amir Ebrahimifakhar

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

This dissertation describes a large-scale investigation of heating, ventilation, and air-conditioning (HVAC) fault prevalence in commercial buildings in the United States. A multi-year dataset with 36,556 pieces of HVAC equipment including air handling units (AHUs), air terminal units (ATUs), and packaged rooftop units (RTUs) was analyzed to determine values for several HVAC fault prevalence metrics. The primary source of data for this study comes from three commercial fault detection and diagnostics (FDD) providers. Since each FDD provider uses different terms to refer to the same fault in an HVAC system, a mapping function was created for each FDD provider’s dataset, …

Phenolic, Carotenoid And Saccharide Compositions Of Vietnamese Camellia Sinensis Teas And Herbal Teas, Danh C. Vu, Sophie Alvarez

Nebraska Center for Biotechnology: Faculty and Staff Publications

Tea (Camellia sinensis) and herbal tea have been recognized as rich sources of bioactive constituents with the ability to exert antioxidant actions. The aims of this study were to analyze phenolic, carotenoid and saccharide contents in a set of Vietnamese tea and herbal tea and compare the results with those of green and black teas marketed in the U.S. In total, 27 phenolics, six carotenoids and chlorophylls, and three saccharides were quantitatively identified. Catechins, quercetin glycosides and chlorogenic acid were the predominating phenolics in the teas, with the concentrations following the order: jasmine/green teas > oolong tea > black tea. …

Expedited Pcr With Stirring, Hendrik J. Viljoen

Department of Chemical and Biomolecular Engineering: Faculty Publications

Disclosed are an apparatus and methods for rapid amplifi cation of nucleic acids . More particularly , the present dis closure relates to an apparatus for mixing a reaction solution during amplification of nucleic acids and to methods for amplifying nucleic acids . Also disclosed are methods for lysing cells in a sample and amplifying nucleic acids .

Expedited Pcr With Stirring, Hendrik Viljoen

Department of Chemical and Biomolecular Engineering: Faculty Publications

Disclosed are an apparatus and methods for rapid amplification of nucleic acids. More particularly, the present dis closure relates to an apparatus for mixing a reaction solution during amplification of nucleic acids and to methods for amplifying nucleic acids. Also disclosed are methods for lysing cells in a sample and amplifying nucleic acids.

The Effects Of The Visual Environment On K-12 Student Achievement, Michael Kuhlenengel, Iason Konstantzos, Clarence E. Waters

Durham School of Architectural Engineering and Construction: Faculty Publications

The varying indoor environments among educational buildings can have an impact on students’ ability to learn. This study looks at field data from 220 classrooms in the Midwest, United States, over a two-year period, to analyze the effects of the visual environment on student achievement. The visual environmental metrics considered within this scope include the three new view metrics introduced within the EN 17037 “Daylight of Buildings” standard (Horizontal Sight Angle, Outside Distance of View, and Number of View Layers), as well as standard daylight and electric lighting metrics, focusing on light availability and glare. To capture student achievement, math …

In Situ Characterization Of Tensile Behavior Of Laser Rapid Solidified Al–Si Heterogeneous Microstructures, Bingqiang Wei, Wenqian Wu, Dongyue Xie, Huai-Hsun Lien, Metin Kayitmazbatir, Amit Misra, Jian Wang

Department of Mechanical and Materials Engineering: Faculty Publications

Heterogeneous Al–Si microstructure comprising of sub-micron-scale Al dendrites and nanoscale Al–Si fibrous eutectic was fabricated by processing as-cast Al-20wt.%Si alloy using laser rapid solidification. In situ tension tests explored high tensile strength ( ∼ 600 MPa) and ductility ( ∼ 10%) and high strain hardening rate ( ∼ 7 GPa). Microstructural characterization revealed the plastic co[1]deformation mechanisms between soft Al dendrites and hard nanoscale Al–Si eutectic. The progression of plasticity in nanoscale Al–Si eutectic with increasing applied strain is accommodated by dislocation plasticity in the nano-Al channels and cracking Si nanofibers. The propagation of nano-cracks is suppressed by surrounding Al, …