Engineering Commons^™

An Unmanned Aerial System For Prescribed Fires, Evan M. Beachly

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

Prescribed fires can lessen wildfire severity and control invasive species, but some terrains may be difficult, dangerous, or costly to burn with existing tools. This thesis presents the design of an unmanned aerial system that can ignite prescribed fires from the air, with less cost and risk than with aerial ignition from a manned aircraft. The prototype was evaluated in-lab and successfully used to ignite interior areas of two prescribed fires. Additionally, we introduce an approach that integrates a lightweight fire simulation to autonomously plan safe flight trajectories and suggest effective fire lines. Both components are unique in that they …

Use Of Long Term Weather Data And Spatially Delineated Field Attributes To Predict Water And Energy Conservation From Variable Rate Irrigation, Sahil Sharma

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

The declining levels of the Ogallala aquifer calls for more judicious use of water. Studies have shown that VRI has the potential for water savings. But adoption of VRI is still very low. The major reason is lack of information on the returns from the VRI systems and its feasibility in different fields. Also, a quantification of the required reduction in prices of VRI is necessary. So, an economic return analysis of VRI strategies was done to compare it to uniform irrigation management (UIM) using a water balance model based on long term weather data and field properties for a …

Generalized Ellipsometry On Complex Nanostructures And Low-Symmetry Materials, Alyssa Mock

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

In this thesis, complex anisotropic materials are investigated and characterized by generalized ellipsometry. In recent years, anisotropic materials have gained considerable interest for novel applications in electronic and optoelectronic devices, mostly due to unique properties that originate from reduced crystal symmetry. Examples include white solid-state lighting devices which have become ubiquitous just recently, and the emergence of high-power, high-voltage electronic transistors and switches in all-electric vehicles. The incorporation of single crystalline material with low crystal symmetry into novel device structures requires reconsideration of existing optical characterization approaches. Here, the generalized ellipsometry concept is extended to include applications for materials with …

Design And Implementation Of A Stand-Alone Tool For Metabolic Simulations, Milad Ghiasi Rad

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

In this thesis, we present the design and implementation of a stand-alone tool for metabolic simulations. This system is able to integrate custom-built SBML models along with external user’s input information and produces the estimation of any reactants participating in the chain of the reactions in the provided model, e.g., ATP, Glucose, Insulin, for the given duration using numerical analysis and simulations. This tool offers the food intake arguments in the calculations to consider the personalized metabolic characteristics in the simulations. The tool has also been generalized to take into consideration of temporal genomic information and be flexible for simulation …

Suitability Of River Delta Sediment As Proppant, Missouri And Niobrara Rivers, Nebraska And South Dakota, 2015, Ronald B. Zelt, Christopher M. Hobza, Bethany L. Burton, Nathaniel J. Schaepe, Nadine M. Piatak-Hackley

United States Geological Survey: Water Reports and Publications

Document abstract

Sediment management is a challenge faced by reservoir managers who have several potential options, including dredging, for mitigation of storage capacity lost to sedimentation. As sediment is removed from reservoir storage, potential use of the sediment for socioeconomic or ecological benefit could potentially defray some costs of its removal. Rivers that transport a sandy sediment load will deposit the sand load along a reservoir-headwaters reach where the current of the river slackens progressively as its bed approaches and then descends below the reservoir water level. Given a rare combination of factors, a reservoir deposit of alluvial sand has …

Physical Water Scarcity Metrics For Monitoring Progress Towards Sdg Target 6.4: An Evaluation Of Indicator 6.4.2 “Level Of Water Stress”, D. Vanhama, A. Y. Hoekstra, Y. Wada, F. Bouraoui, A. De Roo, Mesfin Mekonnen, W. J. Van De Bund, O. Batelaan, P. Pavelic, W. G.M. Bastiaanssen, M. Kummu, J. Rockström, J. Liu, B. Bisselink, P. Ronco, A. Pistocchi, G. Bidoglio

Daugherty Water for Food Global Institute: Faculty Publications

Target 6.4 of the recently adopted Sustainable Development Goals (SDGs) dealswith the reduction ofwater scarcity. To monitor progress towards this target, two indicators are used: Indicator 6.4.1 measuring water use efficiency and 6.4.2 measuring the level of water stress (WS). This paper aims to identify whether the currently proposed indicator 6.4.2 considers the different elements that need to be accounted for in a WS indicator.WS indicators compare water use with water availability.We identify seven essential elements: 1) both gross and net water abstraction (or withdrawal) provide important information to understand WS; 2) WS indicators need to incorporate environmental flow requirements …

Water Use In Irrigated Agriculture: An Approach To Water Productivity In Drip And Sprinkler Systems, Fernanda Lamede Ferreira De Jesus, Jéssica Garcia Nascimento, Rubens Duarte Coelho, Sergio Nascimento Duarte, Fernando Campos Mendonça

Daugherty Water for Food Global Institute: Faculty Publications

Irrigation plays an important role in agriculture and the increase in the irrigated area and scarce water resources have encouraged the use of irrigation systems and management systems that increase the efficiency of water use. Thus, maximize water productivity has been one of the most important challenges in agriculture. The present study aimed to relate information on water productivity for two irrigation systems, drip and sprinkler systems, with the purpose of understanding the characteristics of these systems and contributing to the advancement of studies and research carried out in the area. Technological innovations aimed at reducing consumption and increasing water …

Biofuels From Crop Residue: Soil Organic Carbon And Climate Impacts In The Us And India, Adam Liska

Adam Liska Papers

The transformation of crop residue to soil organic carbon and CO₂ is a conserved process that occurs globally. Due to the mathematics of carbon intensity calculations found in government regulations, the amount of CO₂ emitted from crop residue per unit of energy in biofuel is largely independent of the amount of residue removed and the location of its removal, as shown by results from the US and India.

Soil organic carbon (SOC) levels are at equilibria determined by carbon inputs from plant material (+I_c) and loss from oxidation to CO₂

Are the US results relevant …

Loss Of Buffer Value Due To Aquifer Depletion: The Case Of High Plains Aquifer, Mani Rouhi Rad, Timothy Foster, Nicholas Brozovic

Daugherty Water for Food Global Institute: Faculty Publications

Existing literature in economics and engineering do not realistically capture the effects of aquifer depletion on loss of profits from agricultural production. While the former literature ignores the physical characteristics of aquifer and the relationship between aquifer levels and groundwater availability, the latter strand of literature does not consider farmers' decisionmaking as a result of aquifer depletion. Misspecification of these relationships and their effect on irrigation decisions can result in misunderstanding the consequences of aquifer depletion and may provide ineffective policies. This paper provides a framework to study the effects of aquifer depletion on the profit of agricultural production. We …

Electrical Characterization Of Irradiated Semiconducting Amorphous Hydrogenated Boron Carbide, George Glen Peterson

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

Semiconducting amorphous partially dehydrogenated boron carbide has been explored as a neutron voltaic for operation in radiation harsh environments, such as on deep space satellites/probes. A neutron voltaic device could also be used as a solid state neutron radiation detector to provide immediate alerts for radiation workers/students, as opposed to the passive dosimetry badges utilized today. Understanding how the irradiation environment effects the electrical properties of semiconducting amorphous partially dehydrogenated boron carbide is important to predicting the stability of these devices in operation. p-n heterojunction diodes were formed from the synthesis of semiconducting amorphous partially dehydrogenated boron carbide on silicon …

Data Extraction From Web Tables: The Devil Is In The Details, George Nagy, Sharad C. Seth, Dongpu Jin, David W. Embley, Spencer Machado, Mukkai Krishnamoorthy

CSE Conference and Workshop Papers

We present a method based on header paths for efficient and complete extraction of labeled data from tables meant for humans. Although many table configurations yield to the proposed syntactic analysis, some require access to semantic knowledge. Clicking on one or two critical cells per table, through a simple interface, is sufficient to resolve most of these problem tables. Header paths, a purely syntactic representation of visual tables, can be transformed (“factored”) into existing representations of structured data such as category trees, relational tables, and RDF triples. From a random sample of 200 web tables from ten large statistical web …

End-To-End Conversion Of Html Tables For Populating A Relational Database, George Nagy, David W. Embley, Sharad C. Seth

CSE Conference and Workshop Papers

Automating the conversion of human-readable HTML tables into machine-readable relational tables will enable end-user query processing of the millions of data tables found on the web. Theoretically sound and experimentally successful methods for index-based segmentation, extraction of category hierarchies, and construction of a canonical table suitable for direct input to a relational database are demonstrated on 200 heterogeneous web tables. The methods are scalable: the program generates the 198 Access compatible CSV files in ~0.1s per table (two tables could not be indexed).

Nuclear Weapons In A Changing Climate: Probability, Increasing Risks, And Perception, Adam Liska, Tyler R. White, Eric Holley, Robert J. Oglesby

Adam Liska Papers

Many people tend to think that the outcome of any nuclear weapons use today will result in an escalatory situation with apocalyptic outcomes for the countries involved. Yet many factors are increasing the probability of the limited use of nuclear weapons (e.g., 1 to 20 warheads) in a range of conflict scenarios. Previous atmospheric model simulations of regional nuclear conflicts employing many relatively small bombs have been estimated to cause a global “nuclear autumn,” with great reductions in agricultural productivity, stratospheric ozone loss, and spread of hazardous radioactive fallout. The totality of these effects would result in widespread damage …

Elastic Properties Of Superconductors And Materials With Weakly Correlated Spins, Christian Binek

Christian Binek Publications

It is shown that in the ergodic regime, the temperature dependence of Young’s modulus is solely determined by the magnetic properties of a material. For the large class of materials with paramagnetic or diamagnetic response, simple functional forms of the temperature derivative of Young’s modulus are derived and compared with experimental data and empirical results. Superconducting materials in the Meissner phase are ideal diamagnets. As such, they display remarkable elastic properties. Constant diamagnetic susceptibility gives rise to a temperature independent elastic modulus for ceramic and single crystalline superconductors alike. The thermodynamic approach established in this report, paves the way to …

Querying And Visualization Of Moving Objects Using Constraint Databases, Semere M. Woldemariam

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

Good querying and visualization of moving objects and their trajectories is still an open problem. This thesis investigates three types of moving objects. First, projectiles, whose parabolic motion is difficult to represent. Second, moving objects that slide down a slope. The representation of these objects is challenging because of their accelerating motion. Third, the motion of migrating animals. The motion of migrating animals is challenging because it also involves some spatio-temporal interpolation. The thesis shows a solution to these problems using ideas from physics and an implementation in the MLPQ constraint databases system. The MLPQ implementation enables several complex spatio-temporal …

Nanomaterials As Stationary Phases And Supports In Liquid Chromatography: A Review, Sandya Beeram, Elliott Rodriguez, Suresh Doddavenkatanna, Zhao Li, Allegra Pekarek, Darin Peev, Kathryn Goerl, Gianfranco Trovato, Tino Hofmann, David S. Hage

David Hage Publications

The development of various nanomaterials over the last few decades has led to many applications for these materials in liquid chromatography (LC). This review will look at the types of nanomaterials that have been incorporated into LC systems and the applications that have been explored for such systems. A number of carbon-based nanomaterials and inorganic nanomaterials have been considered for use in LC, ranging from carbon nanotubes, fullerenes and nanodiamonds to metal nanoparticles and nanostructures based on silica, alumina, zirconia and titanium dioxide. Many ways have been described for incorporating these nanomaterials into LC systems. These methods have included covalent …

The Magnetic, Electrical And Structural Properties Of Copper-Permalloy Alloys, Makram A. Qader, A. Vishina, Lei Yu, Cougar Garcia, Rakesh K. Singh, Nicholas D. Rizzo, Mengchu Huang, Ralph Chamberlin, Kirill Belashchenko, Mark Van Schilfgaarde, N. Newman

Kirill Belashchenko Publications

Copper-permalloy [Cu_1–x(Ni₈₀Fe₂₀)_x] alloy films were deposited by co-sputtering and their chemical, structural, magnetic, and electrical properties were characterized. These films are found to have favorable weak ferromagnetic properties for low temperature magnetoelectronic applications. Our results show that by varying the composition, the saturation magnetization (M_s) can be tuned from 700 emu/cm³ to 0 and the Curie temperature (T_c), can be adjusted from 900 K to 0 K. The M_s and T_c are found to scale linearly between x = 25% and 100%. Electronic structure calculations …

Geometry-Based Mass Grading Of Mango Fruits Using Image Processing, M. A. Momin, Md Towfiqur Rahman, M. S. Sultana, C. Igathinathane, A. T. M. Ziauddin, T. E. Grift

Biological Systems Engineering: Papers and Publications

Mango (Mangifera indica) is an important, and popular fruit in Bangladesh. However, the post-harvest processing of it is still mostly performed manually, a situation far from satisfactory, in terms of accuracy and throughput. To automate the grading of mangos (geometry and shape), we developed an image acquisition and processing system to extract projected area, perimeter, and roundness features. In this system, images were acquired using a XGA format color camera of 8-bit gray levels using fluorescent lighting. An image processing algorithm based on region based global thresholding color binarization, combined with median filter and morphological analysis was developed …

Evaluating The Impacts Of Farmers’ Behaviors On A Hypothetical Agricultural Water Market Based On Double Auction, Erhu Du, Ximing Cai, Barbara Minsker

Daugherty Water for Food Global Institute: Faculty Publications

Agricultural water markets are considered effective instruments to mitigate the impacts of water scarcity and to increase crop production. However, previous studies have limited understanding of how farmers’ behaviors affect the performance of water markets. This study develops an agent-based model to explicitly incorporate farmers’ behaviors, namely irrigation behavior (represented by farmers’ sensitivity to soil water deficit k) and bidding behavior (represented by farmers’ rent seeking l and learning rate b), in a hypothetical water market based on a double auction. The model is applied to the Guadalupe River Basin in Texas to simulate a hypothetical agricultural water market under …

In Situ Electron Microscopy Of Plasmon-Mediated Nanocrystal Synthesis, Peter Sutter, Ying Li, Christos Argyropoulos, Eli A. Sutter

Department of Electrical and Computer Engineering: Faculty Publications

Chemical processes driven by nonthermal energy (e.g., visible light) are attractive for future approaches to energy conversion, synthesis, photocatalysis, and so forth. The growth of anisotropic metal nanostructures mediated by excitation of a localized surface plasmon resonance (LSPR) is a prototype example of such a reaction. Important aspects, notably the growth mechanism and a possible role of plasmonic “hot spots” within the metal nanostructures, remain poorly understood. Here, we use in situ electron microscopy to stimulate and image the plasmon-mediated growth of triangular Ag nanoprisms in solution. The quantification of the time-dependent evolution of the lateral size and thickness of …

Fabrication And Study Of The Structure And Magnetism Of Rare-Earth Free Nanoclusters, Bhaskar Das

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

No abstract provided.

Superpositioning High Power Lasers For Mid-Air Image Formations, Auston Viotto

UCARE Research Products

This research evaluates different methods to create voxels, 3-dimensional pixels, in air without the need for special glasses or reflections off of surfaces. Research on the advantages of superimposing or the culmination, focusing, of laser light will be conducted. The point of superpositioning/culmination will be evaluated by the brightness of the voxel due to the Rayleigh Scatter Effect. The voxel’s brightness is dependent on the laser output strength and inversely proportional to its wavelength. Once a superimposed/culminated voxel has been created in the lab the next step will be to manipulate the location of the voxel through 3-dimensional space. This …

Influence Of Internal Variability On Population Exposure To Hydroclimatic Changes, Justin S. Mankin, Daniel Viviroli, Mesfin Mekonnen, Arjen Y. Hoekstra, Radley M. Horton, Jason E. Smerdon, Noah S. Diffenbaugh

Daugherty Water for Food Global Institute: Faculty Publications

Future freshwater supply, human water demand, and people’s exposure to water stress are subject to multiple sources of uncertainty, including unknown future pathways of fossil fuel and water consumption, and ‘irreducible’ uncertainty arising from internal climate system variability. Such internal variability can conceal forced hydroclimatic changes on multi-decadal timescales and near-continental spatial-scales. Using three projections of population growth, a large ensemble from a single Earth system model, and assuming stationary per capita water consumption, we quantify the likelihoods of future population exposure to increased hydroclimatic deficits, which we define as the average duration and magnitude by which evapotranspiration exceeds precipitation …

Formation Of Mound-Like Multiscale Surface Structures On Titanium By Femtosecond Laser Processing, Edwin Peng, Alfred Tsubaki, Craig A. Zuhlke, Ryan Bell, Meiyu Wang, Dennis R. Alexander, George Gogos, Jeffrey E. Shield

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

Surface Functionalization Technique • Femtosecond Laser Surface Processing (FLSP) • Utilize high power, femtosecond (10-15 s) laser pulses • Produce self-organized, multiscale surface micro/nanostructures • Diverse range of applicable substrates: semiconductors, metals, polymers, & composites

Why? • What are the different types of FLSP structures on Ti? • Physical evidence needed for FLSP formation models • Optimize FLSP of Ti for biomedical & other applications

How? • Obtain evidence of mound growth processes by examining underlying microstructure • Utilize dual beam Scanning Electron Microscope-Focused Ion Beam instrument to cross section surface structures & fabricate transmission electron microscopy samples

Women In It: Be The Change, Marcia L. Dority Baker

Information Technology Services: Publications

The influence of established women in IT — specifically Florence Hudson and Melissa Woo — encouraged a librarian to apply for a position in Information Technology Services at the University of Nebraska–Lincoln.

A hands-on approach to planning the IT Leadership conference developed a strong collaborative network that also helped grow attendance.

Paying attention to the pros and cons of the 2016 conference guided the planners in modifying their approach to the upcoming October 2017 conference and its focus on diversity and inclusion.

A main goal for future IT Leadership conferences focusing on women and diversity in IT is providing attendees …

Remediating 1,4-Dioxane-Contaminated Water With Slow-Release Persulfate And Zerovalent Iron, Ann Kambhu, Megan Gren, Wei Tang, Steve D. Comfort, Clifford Harris

Nebraska Water Center: Faculty Publications

1,4-dioxane is an emerging contaminant that was used as a corrosion inhibitor with chlorinated solvents. Metal-activated persulfate can degrade dioxane but reaction kinetics have typically been characterized by a rapid decrease during the first 30 min followed by either a slower decrease or no further change (i.e., plateau). Our objective was to identify the factors responsible for this plateau and then determine if slow-release formulations of sodium persulfate and Fe⁰ could provide a more sustainable degradation treatment. We accomplished this by conducting batch experiments where Fe⁰-activated persulfate was used to treat dioxane. Treatment variables included the timing …

Effects Of Initial Aquifer Conditions On Economic Benefits From Groundwater Conservation, T. Foster, N. Brozovic, A. P. Butler

Daugherty Water for Food Global Institute: Faculty Publications

Worldwide, there is growing recognition of the need to reduce agricultural groundwater use in response to rapid rates of aquifer depletion. To date, however, few studies have evaluated how benefits of conservation vary along an aquifer’s depletion pathway. To address this question, we develop an integrated modeling framework that couples an agro-economic model of farmers’ field-level irrigation decisionmaking with a borehole-scale groundwater flow model. Unique to this framework is the explicit consideration of the dynamic reductions in well yields that occur as an aquifer is depleted, and how these changes in intraseasonal groundwater supply affect farmers’ ability to manage production …

The Irreversible Momentum Of Clean Energy, Barack Obama

US Department of Energy Publications

The release of carbon dioxide (CO₂) and other greenhouse gases (GHGs) due to human activity is increasing global average surface air temperatures, disrupting weather patterns, and acidifying the ocean. Left unchecked, the continued growth of GHG emissions could cause global average temperatures to increase by another 4°C or more by 2100 and by 1.5 to 2 times as much in many midcontinent and far northern locations. Although our understanding of the impacts of climate change is increasingly and disturbingly clear, there is still debate about the proper course for U.S. policy—a debate that is very much on display …

Intercomparison Of Modis And Viirs Fire Products In Khanty-Mansiysk Russia: Implications For Characterizing Gas Flaring From Space, Ambrish Sharma, Jun Wang, Elizabeth M. Lennartson

Department of Earth and Atmospheric Sciences: Faculty Publications

Gas flaring is commonly used by industrial plants for processing oil and natural gases in the atmosphere, and hence is an important anthropogenic source for various pollutants including CO₂, CO, and aerosols. This study evaluates the feasibility of using satellite data to characterize gas flaring from space by focusing on the Khanty-Mansiysk Autonomous Okrug in Russia, a region that is well known for its dominant gas flaring activities. Multiple satellite-based thermal anomaly data products at night are intercompared and analyzed, including MODIS (Moderate Resolution Imaging Spectroradiometer) Terra level 2 Thermal Anomalies product (MOD14), MODIS Aqua level 2 Thermal …

Band-To-Band Transitions, Selection Rules, Effective Mass, And Excitonic Contributions In Monoclinic Β-Ga2o3, Alyssa Mock, Rafal Korlacki, Chad Briley, Vanya Darakchieva, Bo Monemar, Yoshinao Kumagai, Ken Goto, Masataka Higashiwaki, Mathias Schubert

Department of Electrical and Computer Engineering: Faculty Publications

We employ an eigenpolarization model including the description of direction dependent excitonic effects for rendering critical point structures within the dielectric function tensor of monoclinic β-Ga₂O₃ yielding a comprehensive analysis of generalized ellipsometry data obtained from 0.75–9 eV. The eigenpolarization model permits complete description of the dielectric response. We obtain, for single-electron and excitonic band-to-band transitions, anisotropic critical point model parameters including their polarization vectors within the monoclinic lattice. We compare our experimental analysis with results from density functional theory calculations performed using the Gaussian-attenuation-Perdew-Burke-Ernzerhof hybrid density functional. We present and discuss the order of the …