Engineering Commons^™

Performance Assessment Of Deteriorated And Retrofitted Steel Hp Piles, Joshua Steelman, Steven Stauffer

Nebraska Department of Transportation: Research Reports

No abstract provided.

Using A Vnir Spectral Library To Model Soil Carbon And Total Nitrogen Content, Nuwan K. Wijewardane

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

n-situ soil sensor systems based on visible and near infrared spectroscopy is not yet been effectively used due to inadequate studies to utilize legacy spectral libraries under the field conditions. The performance of such systems is significantly affected by spectral discrepancies created by sample intactness and library differences. In this study, four objectives were devised to obtain directives to address these issues. The first objective was to calibrate and evaluate VNIR models statistically and computationally (i.e. computing resource requirement), using four modeling techniques namely: Partial least squares regression (PLS), Artificial neural networks (ANN), Random forests (RF) and Support vector regression …

Efficiency Of Chlorophyll In Gross Primary Productivity: A Proof Of Concept And Application In Crops, Anatoly A. Gitelson, Yi Peng, Andrés Viña, Timothy J. Arkebauer, James S. Schepers

Department of Agricultural and Biological Systems Engineering: Faculty Publications

One of the main factors affecting vegetation productivity is absorbed light, which is largely governed by chlorophyll. In this paper, we introduce the concept of chlorophyll efficiency, representing the amount of gross primary production per unit of canopy chlorophyll content (Chl) and incident PAR. We analyzed chlorophyll efficiency in two contrasting crops (soybean and maize). Given that they have different photosynthetic pathways (C3 vs. C4), leaf structures (dicot vs. monocot) and canopy architectures (a heliotrophic leaf angle distribution vs. a spherical leaf angle distribution), they cover a large spectrum of biophysical conditions. Our results show that chlorophyll efficiency in primary …

Carbon Nanotubes Affect The Toxicity Of Cuo Nanoparticles To Denitrification In Marine Sediments By Altering Cellular Internalization Of Nanoparticle, Xiong Zheng, Yinglong Su, Yinguang Chen, Rui Wan, Mu Li, Haining Huang, Xu Li

Department of Civil and Environmental Engineering: Faculty Publications

Denitrification is an important pathway for nitrate transformation in marine sediments, and this process has been observed to be negatively affected by engineered nanomaterials. However, previous studies only focused on the potential effect of a certain type of nanomaterial on microbial denitrification. Here we show that the toxicity of CuO nanoparticles (NPs) to denitrification in marine sediments is highly affected by the presence of carbon nanotubes (CNTs). It was found that the removal efficiency of total NO_X⁻-N (NO₃⁻-N and NO₂⁻-N) in the presence of CuO NPs was only 62.3%, but it …

Development Of A Transition Between An Energy-Absorbing Concrete Barrier And A Rigid Concrete Buttress, Tyler Schmidt

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

From 2010 to 2015, MwRSF researchers developed the RESTORE barrier, which is a restorable MASH TL-4 median barrier with a steel and concrete rail supported by elastomer posts and steel skids. The research effort reported herein describes the initial development of a transition from the RESTORE barrier to a rigid TL-4 concrete buttress.

The previously-developed RESTORE barrier LS-DYNA model was validated against three full-scale vehicle crash tests. Several design concepts were generated through a series of brainstorming efforts. The primary transition concept consisted of a pin and loop connection between the RESTORE barrier and rigid concrete buttress, which was designed …

Mash Test Nos. 3-11 And 3-10 On A Non-Proprietary Cable Median Barrier, Justine E. Kohtz, Robert W. Bielenberg, Scott K. Rosenbaugh, Ronald K. Faller, Karla A. Lechtenberg, John D. Reid

Nebraska Department of Transportation: Research Reports

The Midwest States Pooled Fund has been developing a new non-proprietary cable median barrier. This system incorporates four evenly spaced cables, Midwest Weak Posts spaced at 8 to 16 ft (2.4 to 4.9 m) intervals, and a bolted, tabbed bracket to attach the cables to each post. Full-scale crash testing was needed to evaluate the barrier’s safety performance. According to the Manual for Assessing Safety Hardware (MASH) updated/proposed testing matrix for cable barriers installed within a 6H:1V or median ditch, a series of eight full-scale tests are required to evaluate the safety performance of a system. A ninth test is …

Focal Adhesion Kinase Regulation In Stem Cell Alignment And Spreading On Nanofibers, Mohammad Nahid Andalib, Jeong Soon Lee, Ligyeom Ha, Yuris A. Dzenis, Jung Yul Lim

Department of Mechanical and Materials Engineering: Faculty Publications

While electrospun nanofibers have demonstrated the potential for novel tissue engineering scaffolds, very little is known about the molecular mechanism of how cells sense and adapt to nanofibers. Here, we revealed the role of focal adhesion kinase (FAK), one of the key molecular sensors in the focal adhesion complex, in regulating mesenchymal stem cell (MSC) shaping on nanofibers. We produced uniaxially aligned and randomly distributed nanofibers from poly(L-lactic acid) to have the same diameters (about 130 nm) and evaluated MSC behavior on these nanofibers comparing with that on flat PLLA control. C3H10T1/2 murine MSCs exhibited upregulations in FAK expression and …

The Use Of Semi-Structured Interviews For The Characterisation Of Farmer Irrigation Practices, Jimmy O’Keeffe, Wouter Buytaert, Ana Mijic, N. Brozovic, Rajiv Sinha

Daugherty Water for Food Global Institute: Faculty Publications

For the development of sustainable and realistic water security, generating information on the behaviours, characteristics, and drivers of users, as well as on the resource itself, is essential. In this paper we present a methodology for collecting qualitative and quantitative data on water use practices through semi-structured interviews. This approach facilitates the collection of detailed information on actors’ decisions in a convenient and cost-effective manner. Semi-structured interviews are organised around a topic guide, which helps lead the conversation in a standardised way while allowing sufficient opportunity for relevant issues to emerge. In addition, they can be used to obtain certain …

Pilot Study To Assess Breathing During Sight-Read Stringed Instrument Performance, Collin T. Erickson, Clark Potter, Gregory Bashford

UCARE: Research Products

For many musicians, one common occurrence during a performance is the presence of stage fright. Stage fright, though not always expressed can influence the confidence and self-esteem of a performer, and thus can affect the quality of the performance. Every day musicians are affected by stage fright, and there has been no exact solution as to how to lessen the feeling of anxiety musicians feel before performing. No data has been collected to find the correlation between the regularity of breathing and the level of stage fright that a person feels during their performance. A way to quantify regularity of …

Agricultural Field Robotics For Plant Data Acquisition, Jeremy S. Blackford, Jared Werner, Tyler A. Troyer, Ethan Nutter

UCARE: Research Products

As the demand for food increases, we are presented with the challenge of producing food more efficiently. With the help of agricultural robots it will be possible to achieve greater yields by the application of seeds, fertilizers and chemicals in the most efficient way possible. With more advanced robotic systems accurate crop data can be obtained to improve farming products and techniques.

Flex-Row is a medium sized agricultural robotic platform built for autonomously traversing through rough fields during multiple crop growing stages. This platform consisting of a flexible frame with the ability to vary both width and height will initially …

Toward Mining Massive And Multi-Dimensional Data For Extreme Hydrometeorological And Climate Event Analyses, Ling Qiu, Francisco Munoz-Arriola, Carlos M. Carrilo

UCARE: Research Products

This poster presents the research on the main patterns of spatial distribution and temporal variability of precipitation and temperature in the Missouri River Basin (MRB). MRB has 117 million acres in cropland, produces of 46%, 22%, and 34% US's wheat, corn, and cattle, respectively. Also, MRB is known for intense weather and extreme climate variability. The approach is to identify different patterns of spatial distribution and temporal variability of precipitation and temperature through the use of a Principal Component Analysis. We have found that precipitation and temperature are the ideal meteorological variable to test spatiotemporal variability of extreme events using …

Coercivity Enhancement And Gamma Phase Avoidance Of Alnico Alloys, Li Zhang

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

The promotion of social progress requires greater levels of energy efficiency, quality and productivity. However, these developments usually come at the cost of the environment. Green technologies such as electric vehicles, wind turbine and solar panels are ironically overshadowed by supply limitations and high prices of rare earth elements. Therefore, it is important to find alternative materials to replace those that contain critical elements. Alnico alloys show high magnetization, high Curie temperature (800°C) and good corrosion resistance, making it one of the best candidates to replace neodymium-based magnets used in electric vehicles.

In this thesis, methods controlling shape anisotropy and …

Interaction Of Fibrinogen With Fibronectin: Purification And Characterization Of A Room Temperature-Stable Fibrinogen-Fibronectin Complex From Normal Human Plasma, Ayman E. Ismail

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

A fibrinogen-fibronectin complex (γγ’pdFI-pdFN) was purified from normal human plasma using a sequence of cryoprecipitation, ammonium sulfate fractionation, and DEAE Sepharose chromatography. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) under reducing condition showed both a 1:1 stoichiometric ratio of fibrinogen (FI) to fibronectin (FN) as well as a stoichiometric ratio of 1:1 of γg to gγ’. The γγ’pdFI-pdFN complex was non-covalent in nature as it was disrupted by affinity adsorption to Gelatin Sepharose where pdFN bound strongly and the disrupted γγ’pdFI fell through the chromatographic column. Surprisingly, the purified γγ’pdFI-pdFN complex was more broadly thermally stable than plasma FI (pdFI) …

Growth, Characterization And Simulation Of Tungsten Selenide Thin Films For Photovoltaic Applications, Qinglei Ma

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

An excellent candidate for an earth abundant absorber material is tungsten selenide (WSe₂) which can be directly grown as a p-type semiconductor with a band gap value that matches well the solar spectrum. Although several fabrication methods were reported, further improvement is highly needed to make high quality WSe₂ films. In addition, the numerical modelling of WSe₂ solar devices is highly desired to assess the overall utility of the material. In this work, the growth and characterization of tungsten selenide thin films are investigated, as well simulations of homo- and hetero-junction devices. In the first part, …

Temporally And Spatially Resolved Quantification Of Hemodynamic Forces And Endothelial Mechanics, Lori M. Lambert

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

The endothelium is a thin layer of endothelial cells that line the interior surface of an artery. Due to their direct contact with blood flow, endothelial cells experience varying hemodynamic forces and respond to these forces by altering their morphology. When plaque and other substances accumulate in the walls of arteries, i.e., atherosclerosis, endothelial cells have abnormal responses to blood flow. Studying atherosclerosis progression is, therefore, a two-fold investigation into 1) the hemodynamic forces that cause endothelial responses, and 2) the biological and mechanical responses of endothelial cells. The ultimate goal of this study was to develop an experimental …

Design And Optimization Of Membrane-Type Acoustic Metamaterials, Matthew G. Blevins

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

One of the most common problems in noise control is the attenuation of low frequency noise. Typical solutions require barriers with high density and/or thickness. Membrane-type acoustic metamaterials are a novel type of engineered material capable of high low-frequency transmission loss despite their small thickness and light weight. These materials are ideally suited to applications with strict size and weight limitations such as aircraft, automobiles, and buildings. The transmission loss profile can be manipulated by changing the micro-level substructure, stacking multiple unit cells, or by creating multi-celled arrays. To date, analysis has focused primarily on experimental studies in plane-wave tubes …

An Evaluation Of Agricultural Tractors Hydraulic Lift Performance, Grant W. Melotz

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

The current OECD Code 2 detailing the procedures for the hydraulic lift test of agricultural tractors, section 4.3, published lift values that were sometimes unattainable. The static weight of 2WD, two wheel drive, and MFWD, mechanical front wheel drive, tractors and the amount of lifting force have increased at a greater rate than the amount of static weight on the front axle. This increase in lifting force has led to a decrease in the percent of weight as the upward support force on the front axle of a tractor. Many of the 2WD and MFWD unballasted tractors tested at the …

Tractor Measurement And Data Acquisition System For Hydraulic Power, Draft Force, And Power Take-Off Torque, James Roeber

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

Numerous advancements in machinery performance of agricultural tractors have been made in recent years. The Organisation for Economic Co-operation and Development (OECD) tests predetermined points (e.g., maximum power and torque) for drawbar, Power Take-Off (PTO), and hydraulic power as separate tests for tractor performance. Testing methods with the tractor operating at a steady state have been done for years, which were uncharacteristic of agricultural tractor operations in field conditions. As part of this thesis work, field usable data acquisition systems (DAQs) were developed to record implement energy consumption (e.g., drawbar loading, PTO torque, and hydraulic power). The system used LabVIEW …

Joint Resource Provisioning In Optical Cloud Networks, Pan Yi

School of Computing: Dissertations, Theses, and Student Research

Resource allocation is an evolving part of many Cloud computing and data center management problems. For infrastructure as a service (IaaS) in the Cloud, the Cloud service provider allocates virtual machines (VMs) to the customers with required CPU, memory and disk configurations. In addition to the computing infrastructures, the bandwidth resources would also be allocated to customers for data transmission between reserved VMs. In the near future, users may also want to reserve multiple virtual data centers (VDCs) to construct their own virtual Cloud, which could be called data center as a service (DCaaS). For these two types of services, …

Towards Building An Intelligent Integrated Multi-Mode Time Diary Survey Framework, Hariharan Arunachalam

School of Computing: Dissertations, Theses, and Student Research

Enabling true responses is an important characteristic in surveys; where the responses are free from bias and satisficing. In this thesis, we examine the current state of surveys, briefly touching upon questionnaire surveys, and then on time diary surveys (TDS). TDS are open-ended conversational surveys of a free-form nature with both, the interviewer and the respondent, playing a part in its progress and successful completion. With limited research available on how intelligent and assistive components can affect TDS respondents, we explore ways in which intelligent systems such as Computer Adaptive Testing, Intelligent Tutoring Systems, Recommender Systems, and Decision Support Systems …

Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

A large number of non-native English speakers may be found in American classrooms, both as listeners and talkers. Little is known about how this population comprehends speech in realistic adverse acoustical conditions. A study was conducted to investigate the effects of background noise level (BNL), reverberation time (RT), and talker foreign accent on native and non-native listeners' speech comprehension, while controlling for English language abilities. A total of 115 adult listeners completed comprehension tasks under 15 acoustic conditions: three BNLs (RC-30, RC-40, and RC-50) and five RTs (from 0.4 to 1.2 s). Fifty-six listeners were tested with speech from native …

Agroecosystem And Ecosystem Resiliency To Extreme Hydrometeorological And Climate Events, Katherine M. Werner

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

The purpose of this study was to understand how a large-scale representation of agroecosystems and ecosystems respond to extreme hydrometeorological and climate extreme events (EHCE) within the Platte River Basin. The ability for agroecosystems and ecosystems to adapt to a changing and variable climate is vital for global water, energy, and food security. Two model experiments were performed, the first with a time span from 2000 to 2013 in which a dynamic leaf area index (LAI) MODIS15A2 product was implemented. The second experiment ran from 1950 through 2013 used a climatological fixed seasonal cycle calculated as the average from the …

Drinking Water: Hard Water (Calcium And Magnesium), Sharon O. Skipton, Bruce I. Dvorak

Department of Civil and Environmental Engineering: Faculty Publications

Hard water isn’t a health hazard but can be a nuisance within the home. Learn how to test water, interpret the results, and choose a treatment.

Water described as “hard” contains high amounts of dissolved calcium and magnesium. Hard water is not a health risk but can be a nuisance because of mineral buildup on plumbing fixtures and poor soap and/or detergent performance.

Water is a good solvent and picks up impurities easily. As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Dissolved calcium and magnesium are the two most …

Drinking Water Treatment: Salt-Free Water “Softener” Options, Bruce I. Dvorak

Department of Civil and Environmental Engineering: Faculty Publications

New no-salt technologies may be effective in treating hard water, but consumers should carefully investigate product claims prior to buying a specific treatment device.

Hard water is not a health risk, but many Nebraska consumers find hard water to be a nuisance because of mineral buildup on plumbing fixtures, including water heaters; unsightly film on glass and crystal wares; and poor soap and/or detergent performance. Water described as “hard” contains high amounts of dissolved calcium and magnesium, which are positively charged contaminants called cations.

Water hardness often is expressed as grains of hardness per gallon of water (gpg) or milligrams …

The Influence Of Sediment Characteristics On The Fate Of Steroidogenic Compounds In Aquatic Systems And The Effects On Progesterone Bioavailability In A Target Organism, Jodi L. Sangster

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

There is growing concern about the biologic effects stemming from steroids in impacted waterways. In aquatic systems, interaction between steroids and sediment influence both contaminant fate as well as subsequent bioavailability to aquatic organisms. The focus of this dissertation research was to gain a better understanding of steroid behavior in aquatic systems based on the physiochemical properties of sediment and to use this knowledge to better understand the biological effects stemming from sediment-associated progesterone exposure. Two natural aquatic sediments, a sand and a silty loam, were selected to represent marked differences in sediments properties. Initially, sorption of 17β-estradiol, estrone, progesterone, …

Microbial Degradation Of Sulfonamide Antibiotics, Rachel Levine

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

Certain microbes can transform antibiotics in the environment. However, little is known about the identity of these microbes and their antibiotic biotransformation processes. The objectives of this study were to (1) isolate bacterial strains capable of transforming antibiotics, (2) determine the biotransformation kinetics of antibiotics, (3) characterize the effects of background carbons on the biotransformation kinetics, and (4) identify biotransformation products under various environmental conditions. Sulfadiazine (SDZ) was used as the model antibiotic in this study due to its frequent occurrence in livestock wastes. Surface soil from a cattle feedlot was collected to enrich potential SDZ degrading bacteria. A mixed …

Volume-Change Restraining Effects In Continuous Precast/Prestressed Bridge Girders, Athul Alex

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

A variety of design and construction practices are feasible when building precast concrete continuous bridges with long spans. Precast, prestressed concrete continuous bridges have been implemented by countries around the world. Although these bridges have been in service for many years, there has been limited verification of the ability of connection to provide the predicted continuity. Subsequently many states in the United States design the girders as simple spans for both dead and live loads without considering any moments developed by the connection. The effect of thermal expansion and contraction is hardly considered in the analysis, even though it is …

Performance Assessment Of Deteriorated And Retrofitted Steel Hp Piles, Steven T. Stauffer

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

Deterioration of aging bridges can be attributed to an assortment of mechanisms throughout the structure, with remediation policies also varying. This study focused on assessing the validity of the Nebraska Department of Roads’ (NDOR) reinforced concrete encasement retrofit for corroded steel HP piles. Experiments were designed and conducted to test the capacity of the NDOR retrofit and evaluate failure limit states. Two pile locations were considered: abutment and pile bent. For each location there was a non-deteriorated, deteriorated, and retrofitted case. These cases represented the pile at key stages during its life. NDOR’s concrete encasement retrofit provided the required stability …

Diffusion Modeling And Device Development For Peritoneal Membrane Oxygenation, Liana Hatoum

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

Acute respiratory distress syndrome (ARDS) is a pulmonary disease that causes hypoxemia and respiratory failure. The mortality rate for ARDS ranges between 27% and 45%. Current treatments including mechanical ventilation and extracorporeal membrane oxygenation (ECMO) are often associated with high risk complications including barotrauma, infection, thrombosis, and hemorrhage. Alternative pulmonary support techniques are needed to improve the survival rate of patients suffering from ARDS. Previous studies introducing pure O₂ gas, perfluorocarbons and red blood cells into the intraperitoneal (IP) cavity have reported no effect or only a mild increase in oxygenation. Here we report peritoneal membrane oxygenation (PMO) using …

Mild Traumatic Brain Injury: Combined In Silico And In Vitro Studies, Yi Hua

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

Mild traumatic brain injury (TBI) is a significant public health concern worldwide and has attracted significant attention due to high-impact sport as well as improvised explosive devices used in military conflicts. The earliest sign of mild TBI is associated with cognitive, behavioral and physical/somatic changes, which are commonly invisible to existing medical techniques. Thus it is essential to target mechanisms of mild TBI and its associated damage measures for earlier diagnosis/treatment and enhanced protection strategies.

In this work, the mechanism of blast-induced mild TBI was inspected through integrated in silico and in vitro models. A three-dimensional (3D) human head model …