Engineering Commons^™

Microfluidic Systems With Embedded Cell Culture Chambers For High Throughput Biological Assays, Arian Jaberi, Amir Monemian Esfahani, Fariba Aghabaglou, Jae Sung Park, Sidy Ndao, Ali Tamayol, Ruiguo Yang

Department of Mechanical and Materials Engineering: Faculty Publications

The ability to generate chemical and mechanical gradients on chips is important both for creating biomimetic designs or enabling high-throughput assays. However, there is still a significant knowledge gap in the generation of mechanical and chemical gradients in a single device. In this study, we developed gradient-generating microfluidic circuits with integrated microchambers to allow cell culture and to introduce chemical and mechanical gradients to cultured cells. A chemical gradient is generated across the microchambers, exposing cells to a uniform concentration of drugs. The embedded microchamber also produces a mechanical gradient in the form of varied shear stresses induced upon cells …

Investigating Factors Predicting Effective Learning In A Cs Professional Development Program For K–12 Teachers, Patrick Morrow

School of Computing: Dissertations, Theses, and Student Research

The demand for K-12 Computer Science (CS) education is growing and there is not an adequate number of educators to match the demand. Comprehensive research was carried out to investigate and understand the influence of a summer two-week professional development (PD) program on teachers’ CS content and pedagogical knowledge, their confidence in such knowledge, their interest in and perceived value of CS, and the factors influencing such impacts. Two courses designed to train K-12 teachers to teach CS, focusing on both concepts and pedagogy skills were taught over two separate summers to two separate cohorts of teachers. Statistical and SWOT …

A Detailed Assessment Of Groundwater Quality In The Kabul Basin, Afghanistan, And Suitability For Future Development, Hussain Ali Jawadi, Jay Sagin, Daniel D. Snow

Nebraska Water Center: Faculty Publications

Kabul is one of the most populated cities in Afghanistan and providing resources to support this population in an arid climate presents a serious environmental challenge. The current study evaluated the quality of local Kabul Basin groundwater to determine its suitability water for drinking and irrigation purposes now and into the future. This aim was aided through groundwater parameter assessment as well as determination ofWater Quality Index (WQI) developed from 15 observation points near the city. The results of our physicochemical analysis illustrate that groundwater in the majority of areas of the Kabul Basin is not generally suitable for human …

A Detailed Assessment Of Groundwater Quality In The Kabul Basin, Afghanistan, And Suitability For Future Development, Hussain Ali Jawadi, Jay Sagin, Daniel D. Snow

Nebraska Water Center: Faculty Publications

Abstract: Kabul is one of the most populated cities in Afghanistan and providing resources to support this population in an arid climate presents a serious environmental challenge. The current study evaluated the quality of local Kabul Basin groundwater to determine its suitability water for drinking and irrigation purposes now and into the future. This aim was aided through groundwater parameter assessment as well as determination ofWater Quality Index (WQI) developed from 15 observation points near the city. The results of our physicochemical analysis illustrate that groundwater in the majority of areas of the Kabul Basin is not generally suitable for …

Engaging Farmers And The Agriculture Industry Through The Testing Agricultural Performance Solutions Program, Charles A. Burr, Daran Rudnick, Matt Stockton, Robert Tigner, Krystle Rhoades

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The University of Nebraska–Lincoln Testing Agricultural Performance Solutions (TAPS) program involves use of farm management competitions to increase engagement across producers, industry, and universities.Participants make several management decisions throughout the growing season in a controlled field trial held at the university research station. Results are analyzed, and awards are presented for most profitable farm, most efficient farm, and farm with the greatest grain yield. The TAPS program involves several techniques for facilitating participatory assistance, including two-way communication and transformational learning. It has resulted in participants' questioning their past management decisions and realizing that they need to improve their marketing skills …

Introduction To Special Issue Of Irrigation Science: Improving Irrigation Management Across The Ogallala Aquifer, Usa, Allan A. Andales, Daran Rudnick, José L. Chávez

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Groundwater stored in aquifers is a major source of irrigation water for many agricultural regions that receive insufficient precipitation for crop production. In the U.S.A., the High Plains aquifer (HPA) that underlies parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming supplies irrigation water for agricultural production. The HPA underlies around 450,658 km² (174,000 mi²) of which the Ogallala aquifer is the principal geologic formation underlying 347,059 km² (134,000 mi²) (Gutentag et al. 1984). The Ogallala aquifer is primarily a water table (unconfined) aquifer with saturated thickness ranging from 0 …

Nebraska State And Federal Tax Issues: Opinions Of Rural Nebraskans, John C. Allen, Sam Cordes, Amy M. Smith, Matt Spilker, Amber Hamilton

Rural Futures Institute: Publications

Includes

Executive summary

Introduction

Methodology

Respondent profile

Findings

Nebraska Tax Issues

Federal Government Deficit Reduction

Federal Taxation Options

Federal Program Reduction Alternatives

Conclusions

Feasibility And Implementation Of Balanced Mix Design In Nebraska, Gabriel Nsengiyumva, Yong-Rak Kim, Jiong Hu

Nebraska Department of Transportation: Research Reports

Balanced mixture design is an alternative asphalt concrete design method that incorporates the performance of mixtures during the design. Balanced mixture design consists of performance test methods and performance criteria. Compared to the existing Superpave design method which mostly relies on volumetrics to design mixtures, balanced mixture design is more suited to account for performance improvements originating from reclaimed asphalt pavement and other foreign additives such as rejuvenators, warm- mix asphalt additives, polymers, and anti-stripping agents. This study investigated the feasibility of the implementation of balanced mixture design in Nebraska mixtures by exploring appropriate test methods (i.e., for fracture and …

Optimizing Membrane Distillation With Solar Thermal Collectors, Andrew Mason, Ben Shulders, Siamak Nejati

UCARE: Research Products

With rising human populations, the demand for freshwater is an ever-growing problem. One emerging technology to combat this problem is membrane distillation (MD). MD has several advantages for water desalination including 100% rejection of solute (salt, heavy metals, etc.) and mergeability with other affordable energy sources (solar heat, electric resistance, etc.) However, at the moment the specific energy consumption (SEC) of MD is very high due to low water production rates and large energy inputs to heat water. In a solar‐assisted design for MD, the high cost of solar collectors (~$200/m2) inhibits the low cost of water production in comparison …

Development And Testing Of A Bridge Rail For Low-Volume Roads, Scott K. Rosenbaugh, Jacob Delone, Ronald K. Faller, Robert W. Bielenberg

Nebraska Department of Transportation: Research Reports

A new steel bridge rail was developed for use on low-volume bridges. The railing consisted 31-in. tall, 12-gauge Wbeam guardrail mounted on S3x5.7 posts, which were supported by steel square-tube sockets attached to the side of the bridge deck. The sockets were to be attached to the steel C-channel that is typically placed along the edges of rural bridge decks in the state of Nebraska. The bridge railing was developed for use on both 7-in. thick cast in place decks and 12-in. thick prestressed concrete beam slabs.

Various welded and bolted socket-to-channel attachment designs were evaluated through dynamic bogie testing …

Colloidal Silica: Cement Enhancing Admixture Product Evaluation, Lieska Halsey, David Hansen

Nebraska Department of Transportation: Research Reports

As Class F- fly ash (F-ash) becomes scarce, PCC engineers will look to other supplemental cementitious materials (SCM) to replace F-ash and its ASR mitigating properties. Colloidal silica (CS), or nano-silica, has been shown to mitigate ASR at certain replacement levels; however, CS cannot be a full replacement of F-ash. Engineers at the Nebraska Department of Transportation (NDOT) learned of CS from a presentation given by Intelligent Concrete, Inc. at the 2019 Nebraska Concrete Professionals Association Conference and decided to investigate the potential use of CS in NDOT concrete mix designs.

Evaluation Of Mixtures And Pavement Performance For Rehabilitation Methods, Mohammad Rahmani, Gabriel Nsengiyumva, Yong-Rak Kim, Jiong Hu

Nebraska Department of Transportation: Research Reports

Pavement rehabilitation practice involves milling an asphalt surface and placing a new layer. The incorporation of reclaimed asphalt pavement (RAP) mixtures brings cost savings and preserves the environment and natural resources. However, the use of recycled materials can compromise pavement performance, in particular, RAP can contribute to cracking because the mixtures with recycled materials become more brittle. In Nebraska, pavement rehabilitation has mostly been conducted by milling old 4-in. asphalt surface and placing a new 4-in. layer. Due to the potentially increased use of RAP mixtures for pavement rehabilitation, it is necessary to look into potential applications of RAP-induced overlay …

Supporting Bridge Management With Advanced Analysis And Machine Learning, Joshua Steelman, Francisco Garcia

Nebraska Department of Transportation: Research Reports

A supplemental Artificial Neural Network (ANN)-based tool was developed to support the Nebraska Department of Transportation (NDOT) in optimizing bridge management investments when choosing between refined modeling, field testing, retrofitting, or bridge replacement. Load ratings typically increase by approximately 15% to 20% when using detailed finite element analysis (FEA) instead of AASHTO approximate analysis methods. The ANN tool is implemented in an Excel spreadsheet to accept ten input parameters readily available to NDOT engineers performing typical load ratings, and predicts FEA- equivalent critical girder distribution factors (GDFs), removing unnecessary conservativism from approximate AASHTO GDFs, potentially justifying load posting removal for …

Effect Of Motor-Assisted Elliptical Training Speed And Body Weight Support On Center Of Pressure Movement Variability, Farahnaz Fallahtafti, Chase M. Pfeifer, Thad W. Buster, Judith M. Burnfield

Department of Mechanical and Materials Engineering: Faculty Publications

Background: A motor-assisted elliptical trainer is being used clinically to help individuals with physical disabilities regain and/or retain walking ability and cardiorespiratory fitness. Unknown is how the device’s training parameters can be used to optimize movement variability and regularity. This study examined the effect of motor-assisted elliptical training speed as well as body weight support (BWS) on center of pressure (CoP) movement variability and regularity during training. Methods: CoP was recorded using in-shoe pressure insoles as participants motor-assisted elliptical trained at three speeds (20, 40, and 60 cycles per minute) each performed at four BWS levels (0%, 20%, 40%, and …

Cross-Domain Identification For Thermal-To-Visible Face Recognition, Cedric Nimpa Fondje, Shuowen Hu, Nathaniel J. Short, Benjamin S. Riggan

Department of Electrical and Computer Engineering: Faculty Publications

Recent advances in domain adaptation, especially those applied to heterogeneous facial recognition, typically rely upon restrictive Euclidean loss functions (e.g., L2 norm) which perform best when images from two different domains (e.g., visible and thermal) are co-registered and temporally synchronized. This paper proposes a novel domain adaptation framework that combines a new feature mapping sub-network with existing deep feature models, which are based on modified network architectures (e.g., VGG16 or Resnet50). This framework is optimized by introducing new cross-domain identity and domain invariance loss functions for thermal-to-visible face recognition, which alleviates the requirement for precisely co-registered and synchronized imagery. We …

Routing Optimization In Heterogeneous Wireless Networks For Space And Mission-Driven Internet Of Things (Iot) Environments, Sara El Alaoui

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

As technological advances have made it possible to build cheap devices with more processing power and storage, and that are capable of continuously generating large amounts of data, the network has to undergo significant changes as well. The rising number of vendors and variety in platforms and wireless communication technologies have introduced heterogeneity to networks compromising the efficiency of existing routing algorithms. Furthermore, most of the existing solutions assume and require connection to the backbone network and involve changes to the infrastructures, which are not always possible -- a 2018 report by the Federal Communications Commission shows that over 31% …

Development And Performance Assessment Of An Integrated Vermifiltration Based Treatment System For The Treatment Of Feedlot Runoff, Rajneesh Singh, Matteo D'Alessio, Yulie Meneses, Shannon L. Bartelt-Hunt, Brian Woodbury, Chittaranjan Ray

Nebraska Water Center: Faculty Publications

The objective of this study was to treat feedlot runoff by developing an ecologically sustainable, affordable, and resilient treatment system having a relatively long life span. Three horizontal flow soil biofilters were utilized in this study: 1) without earthworms and plants (Biofilter (BF)), 2) with earthworms only (Vermifilter (VF)), and 3) with earthworms and plants (Macrophyte Assisted Vermifilter (MAVF)). The experiments were conducted with a hydraulic retention time of four days using Lumbricus terestrris earthworms and Carex frankii wetland plants. The average COD removal from the BF, VF, and MAVF were 23.2–30.4%, 61.4–69.1%, and 68.3–78.1%, respectively. Average TN removal efficiencies …

Functional Characterization Of Petiolule-Like Pulvinus (Plp) Gene In Abscission Zone Development In Medicago Truncatula And Its Application To Genetic Improvement Of Alfalfa, Juan Du, Shaoyun Lu, Maofeng Chai, Chuanen Zhou, Liang Sun, Yuhong Tang, Jin Nakashima, Jaydeep Kolape, Zhaozhu Wen, Marjan Behzadirad, Tianxiu Zhong, Juan Sun, Yunwei Zhang, Zeng-Yu Wang

Nebraska Center for Biotechnology: Faculty and Staff Publications

Alfalfa (Medicago sativa L.) is one of the most important forage crops throughout the world. Maximizing leaf retention during the haymaking process is critical for achieving superior hay quality and maintaining biomass yield. Leaf abscission process affects leaf retention. Previous studies have largely focused on the molecular mechanisms of floral organ, pedicel and seed abscission but scarcely touched on leaf and petiole abscission. This study focuses on leaf and petiole abscission in the model legume Medicago truncatula and its closely related commercial species alfalfa. By analysing the petiolule-like pulvinus (plp) mutant in M. truncatula at phenotypic level …

Differences In Soil Water Changes And Canopy Temperature Under Varying Water × Nitrogen Sufficiency For Maize, Tsz Him Lo, Daran Rudnick, Kendall C. Dejonge, Geng Bai, Hope Njuki Nakabuye, Abia Katimbo, Yufeng Ge, Trenton E. Franz, Xin Qiao, Derek M. Heeren

West Central Research and Extension Center, North Platte

Crop nitrogen (N) status is known to affect crop water status and crop water use. To investigate further the N effects on soil water changes and on canopy temperature, three water levels × four N levels were imposed on two growing seasons of maize in west central Nebraska, USA. Soil water changes were measured using a neutron probe, whereas canopy temperature was measured using infrared thermometers on a ground-based mobile platform. At all water levels, soil water losses over monthlong intervals were generally greater as N levels increased. Given equal water levels, early afternoon canopy temperatures were usually lower with …

Resilience In Nonmetropolitan Nebraska: Capacity To Overcome Disasters And Hardships, 2020 Nebraska Rural Poll Results, Rebecca Vogt, Cheryl Burkhart-Kriesel, Brad Lubben, L.J. Mcelravy, Timothy Meyer, Steve Schulz, Jason L. Weigle

Rural Futures Institute: Publications

The definition of resilience is the capacity to recover quickly from difficulties. Synonyms include toughness, perseverance and grit. Last spring’s severe weather events and this year’s ongoing COVID-19 pandemic are likely testing the resilience of rural Nebraskans. Given that, how do rural Nebraskans rate their communities on dimensions that measure their resiliency? How confident are they that the federal government or local emergency management authorities can contain infectious disease outbreaks? How do they rate their ability to help their community handle adversities? How prepared are rural Nebraskans to deal with financial emergencies? This paper provides a detailed analysis of these …

Quantitative Assessment Of Alkali-Silica Reaction In Small And Large-Scale Concrete Specimens Utilizing Nonlinear Acoustic Techniques, Clayton Malone

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

Nonlinear resonance techniques have been shown to be sensitive to microcracking in materials, including alkali-silica reaction (ASR) damage in concrete. However, application of nonlinear resonance tests have been limited due to the difficulty of application to large-scale field structures and the inability to quantitatively relate material nonlinearity with damage development. In this study, the development of ASR in concrete prisms and large concrete beam specimens of varying aggregate types and specimen sizes was monitored using linear and nonlinear resonance techniques.

For the concrete prisms, although the linear resonance frequency test could detect initiation and development of ASR damage in specimens …

Free Charge Carrier Properties In Two-Dimensional Materials And Monoclinic Oxides Studied By Optical Hall Effect, Sean Knight

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

In this dissertation, optical Hall effect (OHE) measurements are used to determine the free charge carrier properties of important two-dimensional materials and monoclinic oxides. Two-dimensional material systems have proven useful in high-frequency electronic devices due to their unique properties, such as high mobility, which arise from their two-dimensional nature. Monoclinic oxides exhibit many desirable characteristics, for example low-crystal symmetry which could lead to anisotropic carrier properties. Here, single-crystal monoclinic gallium oxide, an AlInN/GaN-based high-electron-mobility transistor (HEMT) structure, and epitaxial graphene are studied as examples. To characterize these material systems, the OHE measurement technique is employed. The OHE is a physical …

Enhanced Control Algorithms In Permanent Magnet Synchronous Machines, Haibo Li

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

Permanent magnet synchronous machines (PMSMs) are gaining increasing popularity in various applications due to their advantages, such as high efficiency, high power density, and superior control performance. A well-designed machine control algorithm is indispensable for a PMSM system to secure its good performance.

In this work, enhanced control algorithms in PMSMs are developed. Online machine current trajectory tracking, source power management, hardware overcurrent regulation, and machine current sensor fault detection and isolation (FDI) are included in the developed algorithms. The online machine current trajectory tracking ensures the maximum torque per ampere (MTPA) or maximum torque per voltage (MTPV) control in …

An End-To-End Trainable Method For Generating And Detecting Fiducial Markers, J. Brennan Peace

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

Existing fiducial markers are designed for efficient detection and decoding. The methods are computationally efficient and capable of demonstrating impressive results, however, the markers are not explicitly designed to stand out in natural environments and their robustness is difficult to infer from relatively limited analysis. Worsening performance in challenging image capture scenarios - such as poorly exposed images, motion blur, and off-axis viewing - sheds light on their limitations. The method introduced in this work is an end-to-end trainable method for designing fiducial markers and a complimentary detector. By introducing back-propagatable marker augmentation and superimposition into training, the method learns …

Life Cycle Assessment Of The Us Beef Processing Through Integrated Hybrid Approach, Shaobin Li, Yuwei Qin, Jeyamkondan Subbiah, Bruce Dvorak

Department of Civil and Environmental Engineering: Faculty Publications

Hybrid life cycle assessment (LCA) incorporating process-based and economic input-output (EIO)–based inventory data has been applied in various industries (e.g., wind energy, biofuel). Few hybrid LCA studies have been found in the food industry. This work analyzes the life cycle environmental impacts of the US beef processing industry using process-based and integrated hybrid LCA. The process-based inventory includes all resource inputs and waste outputs associated with a beef processing plant. The EIO-based inventory includes key activities missing in the process-based inventory, such as technical and management service, wood and paper, and industrial equipment. Ten environmental impact categories from TRACI v2.1 …

Development Of Novel Catalysts For Hydrogen Gas Production From Biomass Compounds, Boanerges Bamaca

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

Hydrothermal biomass gasification technologies (sub- and supercritical water gasification and aqueous-phase reforming) have considerable economic, environmental, and technical advantages over other energy-extensive technologies (e.g. natural gas reforming) for hydrogen gas production. However, lack of economically feasible and highly active catalysts is a main challenge that impedes upscaling of these technologies for hydrogen gas production.

The goal of this study was to develop innovative, economically feasible and active heterogeneous supported metal catalysts for hydrothermal processes for producing hydrogen gas from biomass-derived compounds. Because of its stable structure and chemical inertness, graphene was used as catalyst support. Graphene supported metal catalysts were …

Brillouin Zone Center Phonon Modes In Znga2O4, Megan Stokey, Rafal Korlacki, Sean Knight, Matthew J. Hilfiker, Zbigniew Galazka, Klaus Irmscher, Vanya Darakchieva, Mathias Schubert

Department of Electrical and Computer Engineering: Faculty Publications

Infrared-active lattice mode properties of melt-grown high-quality single bulk crystals of ZnGa₂O₄ are investigated by combined spectroscopic ellipsometry and density functional theory computation analysis. The normal spinel structure crystals are measured by spectroscopic ellipsometry at room temperature in the range of 100 cm^–1–1200 cm^–1. The complex-valued dielectric function is determined from a wavenumber-by-wavenumber approach, which is then analyzed by the four-parameter semi-quantum model dielectric function approach augmented by impurity mode contributions. We determine four infrared-active transverse and longitudinal optical mode pairs, five localized impurity mode pairs, and the high frequency dielectric constant. All …

Climate Change And Market-Based Insurance Feedbacks, Eric R. Holley, Adam Liska, Cory Walters, Geoffrey C. Friesen, Michael Hayes, Max J. Rudolph, Donald A. Wilhite

Adam Liska Papers

Climatic events have accounted for 91% of $1.05 trillion in insured costs for global catastrophic events from 1980 to 2016. Costs are driven by socio-economic development and increased frequency and severity of climatic disasters driven by climate change. Government policies to reduce systemic risk (e.g., cap-and-trade, carbon tax) have been a predominant approach for mitigation and adaptation. Alternatively, market-based incentives for climate change adaptation and mitigation already operate via the insurance industry to lessen impacts on society. Insurance feedbacks include changes in 1) premiums and insurance policies, 2) non-coverage, and 3) policy making and litigation. Alongside government policies, insurance feedbacks …

Pesticide Occurrence And Persistence Entering Recreational Lakes Residing In Watersheds Of Various Land Uses, Jessica Satiroff

Department of Environmental Engineering: Theses and Other Student Research

Common Use Pesticides (CUPs) are important for agricultural producers to sustain food production. As a result, regions with high rates of agricultural production, such as the Midwest, often have ubiquitous occurrences of pesticides in surface and groundwater ¹. Once pesticides are introduced into an ecosystem, pesticides have the potential for creating unwanted effects on non-target species and downstream environments ^2,3. However, pesticides do not come strictly from agricultural practices. Therefore, the research presented in this thesis focuses on the neonicotinoid and fungicide concentrations detected in recreational lakes as well as their persistence in these aquatic environments during the …

Biofiltration Of Volatile Organic Compounds Emitted At Ethanol Plants, Mitham Al-Faliti

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

Ethanol is a major biofuel source of energy in the U.S. Ethanol production produces several harmful emissions from both fermentation tanks and dryers. CO₂ scrubbers control the emissions from the fermentation tanks, while the emissions from the dryers are controller by regenerative thermal oxidizers. These methods are expensive to operate. A potential alternative is bio-trickling filters. Bio-trickling filters are an inexpensive and environmentally friendly alternative. For this study, two parallel bio-trickling filters were operated one at 25°C called the mesophilic bio-trickling filter and one at 60°C called the thermophilic bio-trickling filter. The mesophilic bio-trickling filter simulates emissions from fermentation …