Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

University of Nebraska - Lincoln

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 871 - 900 of 11222

Full-Text Articles in Engineering

Evaluation Of Selected Computer Software For Concussion Recovery And Diagnosis, J.P. Jensen May 2022

Evaluation Of Selected Computer Software For Concussion Recovery And Diagnosis, J.P. Jensen

Honors Program: Senior Projects (Public)

Acquired traumatic brain injuries, such as concussions, impact many athletes participating in sports, particularly at the high school, collegiate, and professional levels. The risks posed by concussions – particularly when an athlete suffers repeated injuries – demands that protocols and tools be developed to maximize athlete health and safety. Computer technology can perform critical roles in the analysis and management of concussions. While specialized devices in the areas of imaging and impact sensing, are most associated with concussion management, researchers within the last two decades have increasingly explored the incorporation of various consumer technologies into the identification and treatment of …


Data Management In Web Applications To Balance Performance And Security, Caleb Marcoux May 2022

Data Management In Web Applications To Balance Performance And Security, Caleb Marcoux

Honors Program: Senior Projects (Public)

As web applications become increasingly popular, many are running several calculations and data processing on the client machine, it is important to consider data management practices on the front-end of these web applications. Typically, some data from the server is stored in the client's memory or hard disk. How much data should be stored for how long, as well as many other considerations, influence the time and space performance of the web application, as well as its security. In this thesis, we explore several challenges, solutions, and design patterns in web application data management through the lens of a senior …


Design Of Hardware To Aid Smartphone-Based Oscilloscope App, Riddock Moran May 2022

Design Of Hardware To Aid Smartphone-Based Oscilloscope App, Riddock Moran

Honors Program: Senior Projects (Public)

A smartphone-based oscilloscope improves on traditional lab oscilloscopes in accessibility and portability but faces several performance limitations compared to traditional oscilloscopes. Among these, an oscilloscope app that uses the phone’s audio to read voltage signals will have a sampling rate and voltage bottlenecked by the capabilities of the audio codec, which will rarely exceed a rate of 48 kHz and 1 volt, respectively. Additionally, smartphones lack the ability to read line-in audio, allowing only one channel input through the microphone. Direct connections to an audio source may not be possible due to requiring an audio jack connection, and different poles …


Designing A Digital Electronics Lab, Ben Buckwalter May 2022

Designing A Digital Electronics Lab, Ben Buckwalter

Honors Program: Senior Projects (Public)

Hardware electronics tools can be more expensive than a new learner is willing to invest resulting in a barrier to entry. Furthermore, it can be difficult for a new learner to know where to start when learning electronics. To resolve this issue, we first explore current mobile app solutions that provide free electronics tooling. Then, we propose a design for a new mobile app that contains basic function generator and oscilloscope functionality as well as the learning resources necessary in order to guide new learners in the basics of digital electronics.


A Physical Model Of Deadmans Run, Quinn Brandt May 2022

A Physical Model Of Deadmans Run, Quinn Brandt

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

A physical model of Deadmans Run and a pair of railroad bridges was constructed to assess the impacts of the bridges on flood flows. Lower Platte South Natural Resources District is planning a series of improvements to Deadmans Run to improve flood conveyance capacity and remove approximately 500 homes and businesses from the floodplain. The rail bridges are located less than a mile from the confluence of Deadmans Run and Salt Creek, meaning the bridges present a significant bottleneck to the planned improvements. The physical model was used to characterize the drag effects caused by the bridges, which was used …


Rheological Behavior Of Dspc-, Dbpc-, And Dppc-Oxygen Microbubbles And Their Effectiveness In Improving Survival In A Rat Model Of Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome, Riaz Ur Rehman Mohammed May 2022

Rheological Behavior Of Dspc-, Dbpc-, And Dppc-Oxygen Microbubbles And Their Effectiveness In Improving Survival In A Rat Model Of Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome, Riaz Ur Rehman Mohammed

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

Acute respiratory distress syndrome (ARDS) causes 75,000 deaths in the U.S., annually. It is characterized by hypoxemia and damage to the lung alveoli. ARDS Management strategies involve extracorporeal membrane oxygenation (ECMO) and mechanical ventilation, but none of these methods improve the mortality rates. Oxygen microbubbles (OMBs) consist of a lipid shell with an oxygen core and have potential to augment oxygenation to manage ARDS. Previous studies demonstrated significant improvements in systemic oxygenation and mortality upon administering OMBs.

We replicated an ARDS rat model by intratracheal administration of lipopolysaccharide at a 24 mg/kg dose. After inducing the disease in rats, the …


An Investigation Of Water Obstructions And Related Weather Conditions For Nebraska Roadways, Mark R. Anderson, Logan R. Bundy May 2022

An Investigation Of Water Obstructions And Related Weather Conditions For Nebraska Roadways, Mark R. Anderson, Logan R. Bundy

Nebraska Department of Transportation: Research Reports

Roadway resilience across the 10,000 miles of road and 3,500 bridges in Nebraska is critical to the economic success of productionand logistics. In a state where historical flooding scenarios, such as the one in March 2019 that caused $150 million in damage,could potentially be increasing, it has become essential to understand the spatial and temporal distribution of high-frequency waterobstruction areas on roadways. Therefore, in order to further investigate these areas, the main objectives of this research were toperform statistical and spatial analyses to quantify the relationship between water obstructions and their associated meteorologicalconditions, and identify the potential linkages between water …


Estimating System And Traveler Costs Due To Lane Closures During Construction And Maintenance Operations, Ernest Tufuor, Li Zhao, Mm Haque, Laurence Rilett Ph.D., John Anderson, Eric Thompson May 2022

Estimating System And Traveler Costs Due To Lane Closures During Construction And Maintenance Operations, Ernest Tufuor, Li Zhao, Mm Haque, Laurence Rilett Ph.D., John Anderson, Eric Thompson

Nebraska Department of Transportation: Research Reports

Lane closures are used to facilitate activities related to road construction and maintenance or operations. However, there are economic costs associated with lane closures and these may accrue to both the traveling public as well as to traffic agencies. The Nebraska Governor’s office has identified maximizing the effectiveness of lane closures as a priority for the Nebraska Department of Transportation (NDOT). The goal of this project is to assist NDOT in effectively managing the operations of work zones to maximize the effectiveness of lane closures under Nebraska conditions. This report summarizes the findings of the current state of the practice …


Estimating System And Traveler Costs Due To Lane Closures During Construction And Maintenance Operations, Ernest Tufuor, Lianlin Zhao, Mm Shakiul Haque, Laurence Rilett, John Anderson, Eric Thompson May 2022

Estimating System And Traveler Costs Due To Lane Closures During Construction And Maintenance Operations, Ernest Tufuor, Lianlin Zhao, Mm Shakiul Haque, Laurence Rilett, John Anderson, Eric Thompson

Nebraska Department of Transportation: Research Reports

Lane closures are used to facilitate activities related to road construction and maintenance or operations. However, there are economic costs associated with lane closures and these may accrue to both the traveling public as well as to traffic agencies. The Nebraska Governor’s office has identified maximizing the effectiveness of lane closures as a priority for the Nebraska Department of Transportation (NDOT). The goal of this project is to assist NDOT in effectively managing the operations of work zones to maximize the effectiveness of lane closures under Nebraska conditions. This report summarizes the findings of the current state of the practice …


Symbolic Ns-3 For Efficient Exhaustive Testing, Jianfei Shao May 2022

Symbolic Ns-3 For Efficient Exhaustive Testing, Jianfei Shao

School of Computing: Dissertations, Theses, and Student Research

Exhaustive testing is an important type of simulation, where a user exhaustively simulates a protocol for all possible cases with respect to some uncertain factors, such as all possible packet delays or packet headers. It is useful for completely evaluating the protocol performance, finding the worst-case performance, and detecting possible design or implementation bugs of a protocol. It is, however, time consuming to use the brute force method with current NS-3, a widely used network simulator, for exhaustive testing. In this paper, we present our work on Sym-NS-3 for more efficient exhaustive testing, which leverages a powerful program analysis technique …


Repair And Strengthening Of Concrete Bridges Using Ultra-High-Performance Concrete (Uhpc), Antony Kodsy May 2022

Repair And Strengthening Of Concrete Bridges Using Ultra-High-Performance Concrete (Uhpc), Antony Kodsy

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Reinforced/Prestressed concrete bridges are subjected to environmental effects that cause premature deterioration and require structural repair and strengthening during their service life. Currently 42% of bridges in the United States are at least 50 years old, and 7.5% of them are structurally deficient and need to be repaired/strengthened. Recently, new repair and strengthening techniques using Ultra-High-Performance concrete (UHPC) have shown a great potential with respect to performance, economy, and speed. UHPC is a new class of concrete that has mechanical and durability properties that are far superior to those of conventional concrete (CC). In addition, UHPC offers several advantages compared …


Inactivation Of Salmonella In Black Peppercorn By Fluidization With Hydrogen Peroxide Vapor, Edel Summers May 2022

Inactivation Of Salmonella In Black Peppercorn By Fluidization With Hydrogen Peroxide Vapor, Edel Summers

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

The purpose of the present study was to assess the effectiveness of hydrogen peroxide vapor (HPV) at inactivating Salmonella inoculated in whole black pepper when used as fluidizing gas media. HPV treatment was conducted at two different temperatures (45°C and 60°C) and two dwell times (30 min and 60 min). Microbial reduction and residual hydrogen peroxide were measured at three storage times: 0 h (immediately after treatment), 24 h and 48 h post-treatment. The effect of HPV on the quality of whole black peppercorn was evaluated 48 h post-treatment based on changes in piperine content, total phenolics, antioxidant activity, total …


Intelligibility Of Medically Related Sentences In Quiet, Speech-Shaped Noise, And Hospital Noise, Tessa Bent, Melissa Baese-Berk, Erica E. Ryherd, Sidney Perry May 2022

Intelligibility Of Medically Related Sentences In Quiet, Speech-Shaped Noise, And Hospital Noise, Tessa Bent, Melissa Baese-Berk, Erica E. Ryherd, Sidney Perry

Durham School of Architectural Engineering and Construction: Faculty Publications

Noise in healthcare settings, such as hospitals, often exceeds levels recommended by health organizations. Although researchers and medical professionals have raised concerns about the effect of these noise levels on spoken communication, objective measures of behavioral intelligibility in hospital noise are lacking. Further, no studies of intelligibility in hospital noise used medically relevant terminology, which may differentially impact intelligibility compared to standard terminology in speech perception research and is essential for ensuring ecological validity. Here, intelligibility was measured using online testing for 69 young adult listeners in three listening conditions (i.e., quiet, speech-shaped noise, and hospital noise: 23 listeners per …


Development Of A Next-Generation Non-Proprietary Portable Concrete Barrier, Riley Ruskamp May 2022

Development Of A Next-Generation Non-Proprietary Portable Concrete Barrier, Riley Ruskamp

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

Portable concrete barriers (PCBs) are segmented barriers made of precast concrete units that are connected by various load-bearing hardware. PCBs are typically used to shield work zones by redirecting errant vehicles upon impact with the barrier system. Most commonly-available PCBs have demonstrated performance issues arising from the sloped face of the barrier, which encourages vehicles to pitch and roll during impact, potentially resulting in vehicle rollover. Concerns also exist regarding the large dynamic deflections exhibited by these systems that can encroach upon the protected work zone or require anchoring to prevent large displacements. In addition to these concerns, the American …


Risk Assessment Of Hazardous Material Transportation For Small And Tribal Communities, Harrison Redepenning May 2022

Risk Assessment Of Hazardous Material Transportation For Small And Tribal Communities, Harrison Redepenning

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

By and large transportation of hazardous materials (HazMat) across the US is increasing, with truck transportation as the most common method of transport. Smaller communities (population <5,000) and Native American communities often lack the economic and political influence to quantify the dangers that HazMat incidents present to the immediate and surrounding areas. Lack of such information is an impediment to adequate preparedness in cases of HazMat incidents. This research focuses on assessing the vulnerability of small and tribal communities in Nebraska to the impacts of highway HazMat incidents. This was done by estimating the expected number and type of HazMat incidents per population in each community. Additionally, statistical analysis was conducted on actual HazMat incidents to determine if small and Native American communities experience a higher rate of incidents per population and per HazMat VMT than large and other small communities respectively. For per population, it was found small versus large is statistically significant while Native American versus other small communities was not significant. For per HazMat VMT, neither comparison was found to be statistically significant. In estimated HazMat incidents, actual HazMat incidents per population, and actual HazMat incidents per HazMat VMT, small communities had higher mean values than their large counterparts. Communities on Native American reservation land experienced a higher estimated and lower actual HazMat incident rate per population than other small communities. For actual HazMat incidents per VMT, Native American communities had a higher rate than other small communities.

Advisor: Aemal Khattak


Experimental And Numerical Analysis Of Soil-Geosynthetic Composite For A Geosynthetic-Reinforced Roadway System, Daniel Robertson May 2022

Experimental And Numerical Analysis Of Soil-Geosynthetic Composite For A Geosynthetic-Reinforced Roadway System, Daniel Robertson

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

The present research conducted tests to evaluate the reinforcing performance of geosynthetics including three geogrids (GG1, GG2, and GG3) and one geotextile (GT) for three different soil types – sand, clay, and red shale. All geosynthetics showed great improvement under the lowest confining pressure. The report concluded that between the Large-Scale Direct Shear test, the Large-Scale Pullout Box, and the FLAC simulation, the three geogrids showed the greatest improvement when conducted with sand. The sand could withstand a much greater normal pressure than either clay or red shale. The biaxial geogrids, GG1 and GG3, had ideal results for lower stress …


Design Of Path Correction For Improved Gait Rehabilitation, Zvonimir Pusnik May 2022

Design Of Path Correction For Improved Gait Rehabilitation, Zvonimir Pusnik

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

Following a serious neurological injury or disease, such as a spinal cord injury or multiple sclerosis, many patients develop impaired gait (the ability to walk). There are many different pieces of equipment to help rehabilitate people with impaired gait, ranging from over ground walking with exoskeletons to treadmills with partial bodyweight support. Since the 1990s and 2000s, elliptical trainers have entered the rehabilitative field as a machine with low impact forces and gait-like motion. This led researchers at Madonna Rehabilitation Hospitals to collaborate with the University of Nebraska-Lincoln to create the Intelligently Controlled Assistive Rehabilitation Elliptical (ICARE).

While the ICARE …


Identification Of Orthologous Gene Groups Using Machine Learning, Dillon Burgess Apr 2022

Identification Of Orthologous Gene Groups Using Machine Learning, Dillon Burgess

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

Identification of genes that show similarity between different organisms, a.k.a orthologous genes, is an open problem in computational biology. The purpose of this thesis is to create an algorithm to group orthologous genes using machine learning. Following an optimization step to find the best characterization based on training data, we represented sequences of genes or proteins with kmer vectors. These kmer vectors were then clustered into orthologous groups using hierarchical clustering. We optimized the clustering phase with the same training data for the method and parameter selection. Our results indicated that use of protein sequences with k=2 and scaling the …


Machine Learning-Based Device Type Classification For Iot Device Re- And Continuous Authentication, Kaustubh Gupta Apr 2022

Machine Learning-Based Device Type Classification For Iot Device Re- And Continuous Authentication, Kaustubh Gupta

School of Computing: Dissertations, Theses, and Student Research

Today, the use of Internet of Things (IoT) devices is higher than ever and it is growing rapidly. Many IoT devices are usually manufactured by home appliance manufacturers where security and privacy are not the foremost concern. When an IoT device is connected to a network, currently there does not exist a strict authentication method that verifies the identity of the device, allowing any rogue IoT device to authenticate to an access point. This thesis addresses the issue by introducing methods for continuous and re-authentication of static and dynamic IoT devices, respectively. We introduce mechanisms and protocols for authenticating a …


Assessment Of Manure Treatment Technology Adoption And Feedlot Runoff Monitoring Opportunities, Juan Carlos Ramos Tanchez Apr 2022

Assessment Of Manure Treatment Technology Adoption And Feedlot Runoff Monitoring Opportunities, Juan Carlos Ramos Tanchez

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

Livestock products contain valuable nutrients that enhance human health, and their production generates positive local and national economic impacts. The livestock sector also deals with large quantities of environmentally important nutrients in manure. The purpose of this thesis is to further the aims of researchers and educators working at the intersection of livestock production and the environment to identify and promote best practices for livestock production and manure management that are economically and environmentally sustainable.

The second chapter explored options to evaluate nutrient flows in feedlot runoff at the pen scale. Pen scale monitoring is an important consideration for research …


Using Cost Simulation And Computer Vision To Inform Probabilistic Cost Estimates, Shu Jing Ding Apr 2022

Using Cost Simulation And Computer Vision To Inform Probabilistic Cost Estimates, Shu Jing Ding

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Cost estimating is a critical task in the construction process. Building cost estimates using historical data from previously performed projects have long been recognized as one of the better methods to generate precise construction bids. However, the cost and productivity data are typically gathered at the summary level for cost-control purposes. The possible ranges of production rates and costs associated with the construction activities lack accuracy and comprehensiveness. In turn, the robustness of cost estimates is minimal. Thus, this study proposes exploring a range of cost and productivity data to better inform potential outcomes of cost estimates by using probabilistic …


Performance Of Concrete With Different Cement Finenesses And Nano-Activators, Brandon Faltin Apr 2022

Performance Of Concrete With Different Cement Finenesses And Nano-Activators, Brandon Faltin

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

The excessive shrinkage in modern concrete is the result of the construction industry in its quest to complete the job as soon as possible. In order to accomplish this, the fineness of cement was increased significantly in recent decades for a faster rate of strength gain. To combat the cement fineness and reverse the trend of shrinkage, the usage of coarse cements and nanoparticles should be strongly considered. The coarse cement is used to reduce the shrinkage of concrete, while the nanoparticle increases the early strength, alleviating the original concerns of reduced early strength when using coarse cement.

Work in …


Neuromorphic Computing Using Electrostatic Mems Devices, Fadi Alsaleem Apr 2022

Neuromorphic Computing Using Electrostatic Mems Devices, Fadi Alsaleem

Durham School of Architectural Engineering and Construction: Faculty Publications

A continuous - time recurrent neural network ( CTRNN ) is described that exploits the nonlinear dynamics of micro electro - mechanical system ( MEMS ) devices to model a neuron in accordance with a neuron rate model that is the basis for dynamic field theory . Each MEMS device in the CTRNN is configured to simulate a neuron population by exploiting the characteristics of bi - stability and hysteresis inherent in certain MEMS device structures . In an embodiment , the MEMS device is a microbeam or cantilevered microbeam device that is excited with an alternating current ( AC …


Characterizing And Predicting Human Visual Perception Of Unmanned Aerial Vehicle Gestures, Paul Fletcher Apr 2022

Characterizing And Predicting Human Visual Perception Of Unmanned Aerial Vehicle Gestures, Paul Fletcher

School of Computing: Dissertations, Theses, and Student Research

Unmanned Aerial Vehicles (UAVs) are being used in public domains and hazardous environments where effective communication strategies are critical. UAV gesture techniques have been shown to communicate meaning to human observers and may be ideal in contexts that require lightweight systems such as unmanned aerial flight, however, this work may be limited to an idealized range of viewer perspectives. As gesture is a visual communication technique it is necessary to consider how the perception of a robot gesture may suffer from obfuscation or self-occlusion from some viewpoints. This thesis presents the results of three online user-studies that examine participants’ ability …


Estimation Of Methane Emissions From Beef Cattle Manure In Nebraska, Noe Hernandez Apr 2022

Estimation Of Methane Emissions From Beef Cattle Manure In Nebraska, Noe Hernandez

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

The emission of methane from livestock production contributes to climate change. Cattle manure accounts for one-third of the total methane emission over the lifecycle of beef and dairy production and represents an opportunity to lower the environmental footprint of the beef industry. While models have been developed to estimate methane emissions from manure under certain types of manure storage methods, there is a lack of a user-friendly interface that agricultural or environmental engineers can use to estimate the methane emission from manure for specific regions. Therefore, the goal of this study was to build an interface to estimate methane emissions …


Program And Proceedings: Nebraska Academy Of Sciences 1880–2022, 142nd Anniversary Year, One Hundred-Thirty-Second Annual Meeting, April 22, 2022 Apr 2022

Program And Proceedings: Nebraska Academy Of Sciences 1880–2022, 142nd Anniversary Year, One Hundred-Thirty-Second Annual Meeting, April 22, 2022

Nebraska Academy of Sciences: Programs and Proceedings

Program

Aeronautics and Space Science

Anthropology

Applied Science and Technology

Biological Sciences

Biomedical Sciences

Chemistry

Earth Sciences

Environmental Sciences

Physics

2022 Maiben Lecture: Dan Sitzman

2022 Friend of Science Award: Julie Sigmon and Chris Schaben


Europium-Doped Cerium Oxide Nanoparticles For Microglial Aβ Clearance And Homeostasis, Jatin Machhi, Pravin Yeapuri, Milica Markovic, Milankumar Patel, Wenhui Yan, Yaman Lu, Jacob D. Cohen, Mahmudul Hasan, Mai Mohamed Abdelmoaty, You Zhou, Huangui Xiong, Xinglong Wang, R. Lee Mosley, Howard E. Gendelman, Bhavesh D. Kevadiya Apr 2022

Europium-Doped Cerium Oxide Nanoparticles For Microglial Aβ Clearance And Homeostasis, Jatin Machhi, Pravin Yeapuri, Milica Markovic, Milankumar Patel, Wenhui Yan, Yaman Lu, Jacob D. Cohen, Mahmudul Hasan, Mai Mohamed Abdelmoaty, You Zhou, Huangui Xiong, Xinglong Wang, R. Lee Mosley, Howard E. Gendelman, Bhavesh D. Kevadiya

Nebraska Center for Biotechnology: Faculty and Staff Publications

Alzheimer’s disease (AD) is the most common neurodegenerative disorder. Pathologically, it is characterized by the deposition of amyloid beta (Aβ) plaques and presence of neurofibrillary tangles. These drive microglia neuroinflammation and consequent neurodegeneration. While the means to affect Aβ plaque accumulation was achieved how it affects disease outcomes remains uncertain. Cerium oxide (CeO2) reduces Aβ plaques, oxidative stress, inflammation, and Alzheimer’s disease (AD) signs and symptoms. Specifically, CeO2 nanoparticles (CeO2NPs) induces free radical scavenging and cell protective intracellular signaling. This can ameliorate the pathobiology of an AD-affected brain. In order to investigate, CeO2NPs …


Surface Urban Energy And Water Balance Scheme (V2020a) In Vegetated Areas: Parameter Derivation And Performance Evaluation Using Fluxnet2015 Dataset, Hamidreza Omidvar, Ting Sun, Sue Grimmond, Dave Bilesbach, Andrew Black, Jiquan Chen, Zexia Duan, Zhiqiu Gao, Hiroki Iwata, Joseph P. Mcfadden Apr 2022

Surface Urban Energy And Water Balance Scheme (V2020a) In Vegetated Areas: Parameter Derivation And Performance Evaluation Using Fluxnet2015 Dataset, Hamidreza Omidvar, Ting Sun, Sue Grimmond, Dave Bilesbach, Andrew Black, Jiquan Chen, Zexia Duan, Zhiqiu Gao, Hiroki Iwata, Joseph P. Mcfadden

Department of Agricultural and Biological Systems Engineering: Faculty Publications

To compare the impact of surface–atmosphere exchanges from rural and urban areas, fully vegetated areas (e.g. deciduous trees, evergreen trees and grass) commonly found adjacent to cities need to be modelled. Here we provide a general workflow to derive parameters for SUEWS (Surface Urban Energy and Water Balance Scheme), including those associated with vegetation phenology (via leaf area index, LAI), heat storage and surface conductance. As expected, attribution analysis of bias in SUEWS-modelled QE finds that surface conductance (gs) plays the dominant role; hence there is a need for more estimates of surface conductance parameters. The workflow …


Reducing Early-Age Shrinkage Cracks Of Bridge Decks And Rails, Soumitra Das, George Morcous, Jiong Hu Apr 2022

Reducing Early-Age Shrinkage Cracks Of Bridge Decks And Rails, Soumitra Das, George Morcous, Jiong Hu

UNL Student Research Days Posters, Graduate

Early-age shrinkage cracking of concrete bridge decks and rails accelerates the penetration of water and chemicals which leads to reinforcement corrosion, delamination, and eventually spalling. All this results in shorter service life, road closure, and costly repair. Development of Low-cement concrete(LCC) mix to reduce early age shrinkage crack through aggregate grading optimization was done in this research work. This approach also reduces concrete cost ($15-$20/cyd) (15–25%) and its carbon footprint (≈15%).


Understanding The Nonlinear Dynamics Governing Vertical-Lift Vehicles With Variable-Speed, Fixed Rotors, Stephanie Vavra, Micah Busboom, Aleea Stanford, Keegan Moore Apr 2022

Understanding The Nonlinear Dynamics Governing Vertical-Lift Vehicles With Variable-Speed, Fixed Rotors, Stephanie Vavra, Micah Busboom, Aleea Stanford, Keegan Moore

UNL Student Research Days Posters, Undergraduate

Problem: Traffic significantly limits travel in urban areas. • The NASA Urban Air Mobility Project is developing an air taxi as an alternative mean of transportation (Fig. 1).

Challenge: Operating rotors at different frequencies may cause the cabin to vibrate at high amplitudes. Such effects are currently unknown.

Objective: Understand the effect of variable speed rotors on passenger comfort.

From the reduced-order modeling simulations, it can be assumed that counteracting the rotor speed in-balances can reduce the displacement and vibrations experienced at the center of the wing. In other words, should a rotor not maintain its optimal operation speed, reducing …