Engineering Commons^™

Analyses, Calibration And Validation Of Evapotranspirationmodels To Predict Grass-Reference Evapotranspiration In Thesenegal River Delta, Koffi Djaman, Hossein Tabari, Alpha B. Balde, Lamine Diop, Koichi Futakuchi, Suat Irmak

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Study region: Grass-reference evapotranspiration estimation by the Penman-Monteithmethod (PM-ETo) requires a number of climate variables which are not always availableat all weather stations. Different alternative ETo equations have been developed and theirutilization for various local climate conditions requires analyses of their accuracy as com-pared to the standardized Penman-Monteith method. There is a significant lack of data andinformation on this topic in the Senegal River Delta (SRD). Study focus: The objective of this study was to evaluate, calibrate and validate six EToequations ((Trabert, Mahringer, Penman1948, Albrecht, Valiantzas1 and Valiantzas2) forthe SRD. Although all six equations showed good agreement with the PM-ETo …

A Multi-Sensor System For High Throughput Field Phenotyping In Soybean And Wheat Breeding, Geng Bai, Yufeng Ge, Waseem Hussain, P. Stephen Baenziger, George L. Graef

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Collecting plant phenotypic data with sufficient resolution (in both space and time) and accuracy represents a long standing challenge in plant science research, and has been a major limiting factor for the effective use of genomic data for crop improvement. This is particularly true in plant breeding where collecting large-scale field-based plant phenotypes can be very labor intensive and costly. In this paper we reported a multi-sensor system for high throughput phenotyping in plant breeding. The system comprised five sensor modules (ultrasonic distance sensors, thermal infrared radiometers, NDVI sensors, portable spectrometers, and RGB web cameras) to measure crop canopy traits …

Recalibration Methodology To Compensate For Changing Fluid Properties In An Individual Nozzle Direct Injection Systems, Joe D. Luck, S. A. Shearer, B. D. Luck, M. P. Sama

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Limited advancement of direct injection pesticide application systems has been made in recent years, which has hindered further commercialization of this technology. One approach to solving the lag and mixing issues typically associated with injection-based systems is high-pressure individual nozzle injection. However, accurate monitoring of the chemical concentrate flow rate can pose a challenge due to the high pressure, low flow, and changing viscosities of the fluid. A methodology was developed for recalibrating high-pressure chemical concentrate injectors to compensate for fluid property variations and evaluate the performance of this technique for operating injectors in an open-loop configuration. Specific objectives were …

A Multi-Scale Comparison Of Modeled And Observed Seasonal Methane Emissions In Northern Wetlands, Xiyan Xu, William J. Riley, Charles D. Koven, Dave P. Billesbach, Rachel Y.-W. Chang, Roisin Commane, Eugenie S. Euskirchen, Sean Hartery, Yoshinobu Harazono, Hiroki Iwata, Kyle C. Mcdonald, Charles E. Miller, Walter C. Oechel, Benjamin Poulter, Naama Raz-Yaseef, Colm Sweeny, Margaret Torn, Steven C. Wofsy, Zhen Zhang, Donatella Zona

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Wetlands are the largest global natural methane (CH₄) source, and emissions between 50 and 70° N latitude contribute 10–30% to this source. Predictive capability of land models for northern wetland CH₄ emissions is still low due to limited site measurements, strong spatial and temporal variability in emissions, and complex hydrological and biogeochemical dynamics. To explore this issue, we compare wetland CH₄ emission predictions from the Community Land Model 4.5 (CLM4.5-BGC) with siteto regional-scale observations. A comparison of the CH₄ fluxes with eddy flux data highlighted needed changes to the model’s estimate of aerenchyma area, which …

Direct And Indirect Effects Of Climatic Variations On The Interannual Variability In Net Ecosystem Exchange Across Terrestrial Ecosystems, Junjiong Shao, Xuhui Zhou, Yiqi Luo, Bo Li, Mika Aurela, David Billesbach, Peter D. Blanken, Rosvel Bracho, Jiquan Chen, Marc Fischer, Yuling Fu, Lianhong Gu, Shijie Han, Yongtao He, Thomas Kolb, Yingnian Li, Zoltan Nagy, Shuli Niu, Walter C. Oechel, Krisztina Pinter, Peili Shi, Andrew Suyker, Margaret Torn, Andrej Varlagin, Huimin Wang, Junhua Yan, Guirui Yu, Junhui Zhang

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Climatic variables not only directly affect the interannual variability (IAV) in net ecosystem exchange of CO2 (NEE) but also indirectly drive it by changing the physiological parameters. Identifying these direct and indirect paths can reveal the underlying mechanisms of carbon (C) dynamics. In this study, we applied a path analysis using flux data from 65 sites to quantify the direct and indirect climatic effects on IAV in NEE and to evaluate the potential relationships among the climatic variables and physiological parameters that represent physiology and phenology of ecosystems. We found that the maximum photosynthetic rate was the most important factor …

Cellulase Immobilization On Superparamagnetic Nanoparticles For Reuse In Cellulosic Biomass Conversion, Qing Song, Yu Mao, Mark Wilkins, Fernando Segato, Rolf Prade

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Current cellulosic biomass hydrolysis is based on the one-time use of cellulases. Cellulases immobilized on magnetic nanocarriers offer the advantages of magnetic separation and repeated use for continuous hydrolysis. Most immobilization methods focus on only one type of cellulase. Here, we report co-immobilization of two types of cellulases, β-glucosidase A (BglA) and cellobiohydrolase D (CelD), on sub-20 nm superparamagnetic nanoparticles. The nanoparticles demonstrated 100% immobilization efficiency for both BglA and CelD. The total enzyme activities of immobilized BglA and CelD were up to 67.1% and 41.5% of that of the free cellulases, respectively. The immobilized BglA and CelD each retained …

Switchgrass Storage Effects On The Recovery Of Carbohydrates After Liquid Hot Water Pretreatment And Enzymatic Hydrolysis, Noaa Frederick, Mengxing Li, Danielle Julie Carrier, Michael D. Buser, Mark R. Wilkins

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Perennial grasses that would be used for bioenergy and bioproducts production will need to be stored for various periods of time to ensure a continual feedstock supply to a bioprocessing facility. The effects of storage practices on grass composition and the response of grasses to subsequent bioprocesses such as pretreatment and enzymatic hydrolysis needs to be understood to develop the most efficient storage protocols. This study examined the effect of outdoor storage of round switchgrass bales on composition before and after liquid hot water pretreatment (LHW) and enzymatic hydrolysis. This study also examined the effect of washing LHW pretreated biomass …

Ecosystem Evapotranspiration: Challenges In Measurements, Estimates, And Modeling, D.M. Amatya, Sibel Irmak, P. Gowda, G. Sun, J.E. Nettles, K.R. Douglas-Mankin

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Evapotranspiration (ET) processes at the leaf to landscape scales in multiple land uses have important con- trols and feedbacks for local, regional, and global climate and water resource systems. Innovative methods, tools, and technologies for improved understanding and quantification of ET and crop water use are critical for adapting more effective management strategies to cope with increasing demand for freshwater resources under global climate change. This article introduces an ASABE Special Collection of 12 articles on ET monitoring and modeling research for multiple land uses and scales. The collection focuses on recent advances in four critical topical areas: (1) reference …

Critical Factors Affecting The Integration Of Biomass Gasification And Syngas Fermentation Technology, Karthikeyan D. Ramachandriya, Dimple K. Kundiyana, Ashokkumar M. Sharma, Ajay Kumar, Hasan K. Atiyeh, Raymond L. Huhnke, Mark R. Wilkins

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Gasification-fermentation is a thermochemical-biological platform for the production of fuels and chemicals. Biomass is gasified at high temperatures to make syngas, a gas composed of CO, CO2, H2, N2 and other minor components. Syngas is then fed to anaerobic microorganisms that convert CO, CO2 and H2 to alcohols by fermentation. This platform offers numerous advantages such as flexibility of feedstock and syngas composition and lower operating temperature and pressure compared to other catalytic syngas conversion processes. In comparison to hydrolysis-fermentation, gasification-fermentation has a major advantage of utilizing all organic components of biomass, including lignin, to yield higher fuel production. Furthermore, …

The Metal/Organic Interface In Cobalt/Vinylidene Fluoride Heterostructures, Keith Foreman, E Echeverria, Mark A. Koten, R. M. Lindsay, N. Hong, Jeffrey E. Shield, Shireen Adenwalla

Shireen Adenwalla Papers

Organic-based electronic devices are rapidly increasing in popularity, making it essential to understand and characterize the interface between organic materials and metallic electrodes. This work reports on the characterization of the interface between thin films of an emerging organic ferroelectric, vinylidene fluoride (VDF) oligomer, and Co, an important high Curie temperature ferromagnet. Using a wide battery of experimental techniques, it is shown that VDF oligomer thin films as thin as 15 nm can halt, or prevent, Co oxidization in atmospheric conditions, a necessary condition for device applications. Selectivity of magnetic properties, such as remanent magnetization, is enabled by the clarification …

Expedient Airfield Runway Repair Using Folded Fiberglass Mat, Christopher Y. Tuan, Willaim C. Dass

Department of Civil and Environmental Engineering: Faculty Publications

For expedient airfield runway repair, the US Air Force has developed a folded fiberglass mat to cover craters repaired with a well-compacted granular base material. The objective of this study was to evaluate the adequacy of using polymer plugs to anchor the mat to a repaired asphalt pavement for heavy aircraft operations. The effort consisted of materials testing, field experiments and analytical modeling. An 89,800-kg (198,000-pound) load cart having the footprint of a single C-5 main gear was pulled on a mat with wheels locked to simulate full braking forces. Anchor bushings were instrumented to measure anchor loads. A simplified …

Field-Scale Testing And Numerical Investigation Of Soil-Boulder Interaction Under Vehicular Impact Using Fem And Coupled Fem-Sph Formulations, Lynsey Reese, Tong Qiu, Daniel Linzell, Zoltan Rado

Department of Civil and Environmental Engineering: Faculty Publications

A computational approach that couples the Finite Element Method and the Smoothed Particle Hydrodynamics method may be advantageous for simulating the response of complex, physical systems involving large deformations. However, comparisons of this modeling technique against field-scale test data are remarkably sparse in literature. This study presents three field-scale tests involving vehicular impact into three landscape vehicular anti-ram barriers. Each barrier consisted of a single boulder embedded in compacted American Association of State Highway and Transportation Officials soil and physical testing resulted in one of the following outcomes: minimal boulder/soil movement (Test 1), moderate boulder/soil movement (Test 2), and severe …

Pch1 Integrates Circadian And Light- Signaling Pathways To Control Photoperiod-Responsive Growth In Arabidopsis, He Huang, Chan Yul Yoo, Rebecca Bindbeutel, Jessica Goldsworthy, Allison Tielking, Sophie Alvarez, Michael J. Naldrett, Bradley S. Evans, Meng Chen, Dmitri A. Nusinow

Nebraska Center for Biotechnology: Faculty and Staff Publications

Plants react to seasonal change in day length through altering physiology and development. Factors that function to harmonize growth with photoperiod are poorly understood. Here we characterize a new protein that associates with both circadian clock and photoreceptor components, named PHOTOPERIODIC CONTROL OF HYPOCOTYL1 (PCH1). pch1 seedlings have overly elongated hypocotyls specifically under short days while constitutive expression of PCH1 shortens hypocotyls independent of day length. PCH1 peaks at dusk, binds phytochrome B (phyB) in a red light-dependent manner, and co-localizes with phyB into photobodies. PCH1 is necessary and sufficient to promote the biogenesis of large photobodies to maintain an …

Heterogeneity Influences On Stream Water–Groundwater Interactions In A Gravel-Dominated Floodplain, R. B. Miller, Derek M. Heeren, Garey A. Fox, Todd Halihan, Daniel E. Storm

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Floodplains are composed of complex depositional patterns of ancient and recent stream sediments, and research is needed to address the manner in which coarse floodplain materials affect stream/groundwater exchange patterns. Efforts to understand the heterogeneity of aquifers have utilized numerous techniques typically focused on point-scale measurements; however, in highly heterogeneous settings, the ability to model heterogeneity is dependent on the data density and spatial distribution. The objective of this research was to investigate the correlation between broad-scale methodologies for detecting heterogeneity and the observed spatial variability in stream/groundwater interactions of gravel-dominated alluvial floodplains. More specifically, this study examined the correlation …

Incorporation Of Globally Available Datasets Into The Roving Cosmic-Ray Neutron Probe Method For Estimating Field-Scale Soil Water Content, William A. Avery, Catherine Finkenbiner, Trenton E. Franz, Tiejun Wang, Anthony L. Nguy-Robertson, Andrew E. Suyker, Timothy J. Arkebauer, Francisco Munoz-Arriola

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The need for accurate, real-time, reliable, and multi-scale soil water content (SWC) monitoring is critical for a multitude of scientific disciplines trying to understand and predict the Earth’s terrestrial energy, water, and nutrient cycles. One promising technique to help meet this demand is fixed and roving cosmic-ray neutron probes (CRNPs). However, the relationship between observed low-energy neutrons and SWC is affected by local soil and vegetation calibration parameters. This effect may be accounted for by a calibration equation based on local soil type and the amount of vegetation. However, determining the calibration parameters for this equation is labor- and time-intensive, …

Csce 411h: Data Modeling For Systems Development—A Peer Review Of Teaching Project Inquiry Portfolio, Hongfeng Yu

UNL Faculty Course Portfolios

A new course CSCE411H has been developed in 2015-2016. The course tackles the learning of traditional and emerging data modeling techniques in big data related areas from the system and application perspectives. The students have mixed background in Business, Engineering, and Art and Science with different levels. These have introduced a unique set of challenges in the development of this new course. In this inquiry portfolio, I investigated if the adjustment of assignments can benefit the team work of the students with a variety of background. Through the data collection and analysis, the investigation showed that the new assignment design …

Ae 2250: Construction Graphics And Design—A Peer Review Of Teaching Project Benchmark Portfolio, Asregedew Woldesenbet

UNL Faculty Course Portfolios

This course portfolio designs and documents AE 2250 (Construction Design and Graphics) course that is taught in Spring 2016 at UNL's College of Engineering under the Durham School of Architectural Engineering and Construction program. The course is intended to introduce BIM (Building Information Modeling) to architectural engineering, construction engineering, construction management and civil engineering students ranging from freshman to juniors. This course portfolio documents the challenges associated with delivering this course, tailors the course objectives, activities and tracking measures to meet the course objectives throughout the semester. This portfolio uses quantitative and qualitative measures to track student performances and learning …

Matl 260/360: Elements Of Materials Science—A Peer Review Of Teaching Project Benchmark Portfolio, Bai Cui

UNL Faculty Course Portfolios

The goal of MATL 260/360 Elements of Materials Science is to make undergraduate students understand the fundamental concepts of the microstructure-property relationship of materials. This course portfolio addresses several key questions in teaching, such as how to teach new knowledge more effectively, how to increase student engagement, how to promote students’ interests and motivations, and how to use this course to improve students’ analysis and critical thinking skills.

To address each of key questions, the course activities include: relating the new knowledge with daily-life and industry examples; giving PPT slides for after- class study; assigning homework questions after each lecture; …

Turning An Organic Semiconductor Into A Low-Resistance Material By Ion Implantation, Beatrice Fraboni, Alessandra Scidà, Piero Cosseddu, Yongqiang Wang, Michael Nastasi, Silvia Milita, Annalisa Bonfiglio

Nebraska Center for Energy Sciences Research: Publications

We report on the effects of low energy ion implantation on thin films of pentacene, carried out to investigate the efficacy of this process in the fabrication of organic electronic devices. Two different ions, Ne and N, have been implanted and compared, to assess the effects of different reactivity within the hydrocarbon matrix. Strong modification of the electrical conductivity, stable in time, is observed following ion implantation. This effect is significantly larger for N implants (up to six orders of magnitude), which are shown to introduce stable charged species within the hydrocarbon matrix, not only damage as is the case …

Ellipsometric Characterization Of Silicon And Carbon Junctions For Advanced Electronics, Alexander G. Boosalis

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

Ellipsometry has long been a valuable technique for the optical characterization of layered systems and thin films. While simple systems like epitaxial silicon dioxide are easily characterized, complex systems of silicon and carbon junctions have proven difficult to analyze. Traditional model dielectric functions for layered silicon homojunctions, a system with a similar structure to modern transistors, often have correlated parameters during ellipsometric data analysis. Similarly, epitaxial graphene as grown from thermal sublimation of silicon from silicon carbide or through chemical vapor deposition, tend to have model dielectric function parameters that correlate with the optical thickness of the graphene due to …

On Problematic Robotic Thresholds, Adam K. Taylor

School of Computing: Dissertations, Theses, and Student Research

Large configuration spaces present difficulties for developers validating large soft- ware systems and for users selecting the proper configuration to achieve the desired runtime behavior. Robot systems face the same challenges as they may have hundreds of configurable parameters. Our work focuses on co-robotic systems, those in which robots and humans work closely together to augment each other’s capabilities. We aim to leverage the user’s knowledge about a system to help determine configuration errors. To accomplish this, users mark runtime failures while observing the system in operation. A marked error indicates the robot “did something when it should not have” …

The Effect Of Manure Application Method On Nutrient And Microbial Runoff Transport And Soil Biological Health Indicators, Nicole R. Schuster

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

Two projects were completed to provide significant new information to the agricultural industry regarding the environmental implications and soil health impacts related to land application of swine manure. The first study reports on the runoff transport of nutrients and microbials as affected by manure application method and time following application. The second study provides information about the effect of application method and time following application on soil health indicators using arthropod abundance and diversity as a biological indicator. The information gained through these studies will provide beneficial information to the pork industry on the impact of manure application method and …

High Throughput Screening Of Priming Candidates For Impact On Nonviral Gene Delivery, Albert L. Nguyen

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

Priming, in the context of nonviral gene delivery, is the treatment of cells with a compound prior to gene transfer that enhances transfection efficiency and/or transgene expression. Essentially, it is the application of an adjuvant approach to gene delivery. Effective transfection strategies may require priming to compete with the efficiency of viral transduction in order to achieve clinically relevant efficiency and expression in vivo. To search for priming compounds, a high throughput screen of the NIH Clinical Collection was performed using 25kDa b-PEI, an EGFP/luciferase plasmid, and HEK293T cells. The EGFP reporter was multiplexed with Hoechst 33342 and Resazurin fluorescence …

Development Of Semi-Circular Bending (Scb) Fracture Test For Bituminous Mixtures, Gabriel Nsengiyumva

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

Granted that most distresses in asphalt (flexible) concrete (AC) pavements are directly related to fracture, it becomes clear that identifying and characterizing fracture properties of AC mixtures is a critical step towards a better pavement design. This thesis examines the testing variables of a reliable and practical semicircular bending (SCB) test for evaluating the fracture characteristics of asphalt concrete mixtures at intermediate service temperature conditions. The first part of this thesis investigates the repeatability of the SCB fracture test method by integrating a statistical-experimental approach to identify testing variables of the SCB test that result in repeatable test results. Toward …

Modeling And Simulation Of Micro Electrical Discharge Machining Process, Bai Shao

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

Micro parts and systems are playing crucial roles in the area of semiconductor, biomedical device, micro fluid devices, automotive, aerospace and so forth. Micro manufacturing is one of the most important technologies in realizing miniaturization. Compared to other micro manufacturing methods, micro-EDM is drawing lots of attention due to its ability to machine complex 3D parts regardless of the hardness of the workpiece material.

Micro-EDM is the cumulative result of numerous single discharges; therefore, it is crucial to understand the single discharge material removal process in micro-EDM. However, due to the stochastic nature and complex process mechanism, micro-EDM, including its …

Field Abundance And Performance Of Hoverflies (Diptera: Syrphidae) On Soybean Aphid, James O. Eckberg, Julie A. Peterson, Colin P. Borsh, Joe M. Kaser, Gregg A. Johnson, John C. Luhman, Donald L. Wyse, George E. Heimpel

West Central Research and Extension Center, North Platte

The management of the soybean aphid Aphis glycines Matsumara is a major challenge to soybean production in the north-central United States. The identification and characterization of the insect predator community has informed integrated pest management strategies by providing insight on predators that can suppress soybean aphid populations. Hoverflies (Diptera: Syrphidae) are known predators of A. glycines, but more information is needed on their diversity, abundance, and performance to evaluate their importance as biological control agents of A. glycines. In this study, syrphid abundance was evaluated across two growing seasons in four soybean fields in east-central Minnesota. Six methods …

Sustainability Assessment For Energy Systems And Chemical Process Industries, Michael J. Matzen

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

Sustainability has become an important factor in the chemical process and energy industries with a strong drive for process improvements towards more environmentally conscious solutions. However, there are many ways of defining sustainability and even more ways of trying to determine how sustainable a process is. This work looks into applying a conjunction of tools including; process simulation, multi-criteria decision matrices and life-cycle assessment to more quantitatively determine sustainability metrics. We have applied these tools for the production of electricity, methanol and dimethyl ether. A novel method of electricity production, in chemical looping combustion (CLC), was used that inherently involves …

Mitigating Pavement Edge Drop Off, Wayne Jensen, Niles Uerling

Nebraska Department of Transportation: Research Reports

The objective of this research was to investigate and document practices currently being used by the Nebraska Department of Roads (NDOR) districts and other State DOTs to mitigate pavement edge drop off. The NDOR has developed (or borrowed) and is currently incorporating into its standard practices several procedures that significantly decrease the incidence and magnitude of pavement edge-drop off. As these practices become more fully integrated into highway reconstruction projects, pavement edge drop off is expected to decrease dramatically. Localized areas of pavement edge drop off along paved lanes with bare or vegetated shoulders were noted as posing particular problems …

Viscoelastic, Fatigue Damage, And Permanent Deformation Characterization Of High Rap Bituminous Mixtures Using Fine Aggregate Matrix (Fam), Hesamaddin Nabizadeh

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

Performance characteristics of bituminous mixtures play the most influential role in designing flexible pavement. These asphaltic mixtures can be considered as heterogeneous mixtures which composed of two primary components: fine aggregate matrix (FAM) phase and aggregate phase. The FAM phase acts as a critical phase in evaluating the performance characteristics including viscoelastic, fatigue damage, and permanent deformation characteristics of entire asphalt mixtures. This study evaluates the viscoelastic, fatigue damage and permanent deformation characteristics of bituminous mixtures containing 65% reclaimed asphalt pavement (RAP) by performing oscillatory torsional shear tests of cylindrical bars of FAM using a dynamic mechanical analyzer. Moreover, this …

Effects Of Sediments On Bmps For Highway Runoff Control, Matthew Garder

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

Numerous studies conducted on highway stormwater runoff and its control with Best Management Practices (BMPs) indicate that sediment is the major pollutant that affects performance and longevity of BMPs. Currently, there are several knowledge gaps related to the effects of sediments on highway BMPs: a) how much sediment will be generated by a construction site by a section of highway with its surrounding watershed under different conditions; b) how sediment is intercepted by different BMPs with or without pretreatment sections; and c) what are the effects of these sediments on BMPs’ hydraulic behavior, longevity, and pollutants removal or release. The …