Engineering Commons^™

Acoustic Attenuation Coefficients For Polycrystalline Materials Containing Crystallites Of Any Symmetry Class, Christopher M. Kube, Joesph A. Turner

Department of Mechanical and Materials Engineering: Faculty Publications

This letter provides a theoretical extension to the elastic properties of polycrystals in order to describe elastic wave scattering from grain boundaries. The extension allows the longitudinal and shear attenuation coefficients for scattering to be derived and is valid for polycrystals containing crystallites of any symmetry class. Attenuation curves are given for polycrystalline SiO₂, ZrO₂, and SnF₂, which contain monoclinic crystallites. This work will allow ultrasonic techniques to be applied to new classes of materials containing nontrivial microstructures.

Air Change Rate Vs Airflow Pathway: Bioaerosol Containment And Removal In Patient Rooms, Kevin R. Grosskopf

Durham School of Architectural Engineering and Construction: Faculty Publications

Recent studies have shown that higher air change rates may have the unintended consequence of creating turbulent airflows that entrain high concentrations of infectious particles within the breathing zone, and possibly, breakdown pressure relationships necessary to contain the spread of infectious particles to other clinical spaces.

Test 2126a: New Holland T8.435, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Attachment Of A Combination Bridge Rail To Concrete Parapet Utilizing Epoxy Adhesive Anchors, Robert W. Bielenberg, John D. Reid, Scott K. Rosenbaugh, Austin J. Haase, Ronald K. Faller

Mid-America Transportation Center: Final Reports and Technical Briefs

The Iowa Department of Transportation (IaDOT) was interested in investigating the use of epoxy adhesive anchorages

for the attachment of posts used in the BR27C combination bridge rail system. Alternative anchorage concepts were developed using a modified version of the ACI 318-11 procedures for embedded anchor design. Four design concepts were developed for review by IaDOT, including: (1) a four-bolt square anchorage, (2) a four-bolt spread anchorage, (3) a two- bolt centered anchorage, and (4) a two-bolt offset anchorage. IaDOT representatives selected the four-bolt spread anchorage and the two-bolt offset anchorage as the preferred designs for evaluation. In addition to …

Nebraska Summary: S992a Massey Ferguson 8735, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Nebraska Summary: S1018a Massey Ferguson 7724, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

The Myth And The Meaning Of Science As A Vocation, Adam Liska

Adam Liska Papers

Many natural scientists of the past and the present have imagined that they pursued their activity according to its own inherent rules in a realm distinctly separate from the business world, or at least in a realm where business tended to interfere with science from time to time, but was not ultimately an essential component, ‘because one thought that in science one possessed and loved something unselfish, harmless, self-sufficient, and truly innocent, in which man’s evil impulses had no part whatever’, as Nietzsche once commented (Nietzsche 1974, p.106). With the extreme technological changes that have occurred in the last fifty …

A Discrete-Time Direct-Torque Control For Direct-Drive Pmsg-Based Wind Energy Conversion Systems, Zhe Zhang, Yue Zhao, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a novel flux space vector-based direct-torque control (DTC) scheme for permanent magnet synchronous generators (PMSGs) used in variable-speed direct drive wind energy conversion systems (WECSs). The discrete time control law, which is derived from the perspective of flux space vectors and load angle, predicts the desired stator flux vector for the next time-step with the torque and stator flux information only. The space-vector modulation (SVM) is then employed to generate the reference voltage vector, leading to a fixed switching frequency as well as lower flux and torque ripples when compared to the conventional DTC. Compared with other …

Femtosecond Laser Induced Tunable Surface Transformations On (111) Si Aided By Square Grids Diffraction, Weina Han, Lan Jiang, Xiaowei Li, Yang Liu, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

We report an extra freedom to modulate the femtosecond laser energy distribution to control the surface ablated structures through a copper-grid mask. Due to the reduced deposited pulse energy by changing the scanning speed or the pulse fluence, a sequential evolution of three distinctly different surface patterns with periodic distributions is formed, namely, striped ripple lines, ripple microdots, and surface modification. By changing the scanning speed, the number of the multiple dots in a lattice can be modulated. Moreover, by exploring the ablation process through the copper grid mask, it shows an abnormal enhanced ablation effect with strong dependence of …

Leveraging Nanocavity Harmonics For Control Of Optical Processes In 2d Semiconductors, Gleb M. Akselrod, Tian Ming, Christos Argyropoulos, Thang B. Hoang, Yuxuan Lin, Xi Ling, David R. Smith, Jing Kong, Maiken H. Mikkelsen

Department of Electrical and Computer Engineering: Faculty Publications

Optical cavities with multiple tunable resonances have the potential to provide unique electromagnetic environments at two or more distinct wavelengthscritical for control of optical processes such as nonlinear generation, entangled photon generation, or photoluminescence (PL) enhancement. Here, we show a plasmonic nanocavity based on a nanopatch antenna design that has two tunable resonant modes in the visible spectrum separated by 350 nm and with line widths of ∼60 nm. The importance of utilizing two resonances simultaneously is demonstrated by integrating monolayer MoS2, a two-dimensional semiconductor, into the colloidally synthesized nanocavities. We observe a 2000-fold enhancement in the PL intensity of …

Skin Effect Mitigation In Laser Processed Multi-Walled Carbon Nanotube/Copper Conductors, K. Keramatnejad, Y. S. Zhou, Y. Gao, H. Rabiee Golgir, M. Wang, L. Jiang, J.F. Silvain, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

In this study, laser-processed multi-walled carbon nanotube (MWCNT)/Cu conductors are introduced as potential passive components to mitigate the skin effect of Cu at high frequencies (0–10 MHz). Suppressed skin effect is observed in the MWCNT/Cu conductors compared to primitive Cu. At an AC frequency of 10 MHz, a maximum AC resistance reduction of 94% was observed in a MWCNT/Cu conductor after being irradiated at a laser power density of 189 W/cm2. The reduced skin effect in the MWCNT/Cu conductors is ascribed to the presence of MWCNT channels which are insensitive to AC frequencies. The laser irradiation process is observed to …

Sustainability And Economic Analysis Of Propylene Carbonate And Polypropylene Carbonate Production Processes Using Co2 And Propylene Oxide, Yaşar Demirel

Yaşar Demirel Publications

Currently, the industrially important polycarbonates are synthesized from bisphenol A and diphenyl carbonate, which are highly toxic and hence other feasible alternatives are preferable. Following the considerable advances on the catalyst for the synthesis of carbonates from CO₂ and propylene oxide (PO), industrial scale processes for the productions of propylene carbonate (PC) and polypropylene carbonate (PPC) have been designed and simulated with sustainability and economic analyses. The CO₂ is supplied by a nearby bioethanol plant, while the PO from a petrochemical process. The first part of the study is for the production of 200 million lb/year cyclic PC …

Theoretical And Experimental Investigation Of An Intensity-Demodulated Fiber-Ring-Laser Ultrasonic Sensor System, G. Liu, Elliott Sandfort, Lingling Hu, Tongqing Liu, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

We theoretically and experimentally investigate the performance of an ultrasound detection system based on a fiber ring laser (FRL) whose cavity includes a pair of fiber Bragg gratings. The ultrasonic detection is achieved by the FRL power variations in response to the ultrasound-induced cold-cavity loss modulation of the FRL. The effects of key FRL parameters, including pump power, laser cold-cavity loss, and laser cavity length, on the system signal-to-noise ratio (SNR) performance have been investigated. It is found that the maximum SNR is achieved when the frequency of the ultrasound is the same as that of the FRL relaxation oscillation …

Fiber-Optic Refractometer Based On A Phase-Shifted Fiber Bragg Grating On A Side-Hole Fiber, Qi Zhang, Lingling Hu, Yuefeng Qi, G. Liu, Natale J. Ianno, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

A fiber-optic refractive index (RI) sensor based on a π-phaseshifted fiber-Bragg-grating (πFBG) inscribed on a side-hole fiber is presented. The reflection spectrum of the πFBG features two narrow notches associated with the two polarization modes and the spectral spacing of the notches is used for high-sensitivity RI sensing with little temperature cross-sensitivity. The side-hole fiber maintains its outer diameter and mechanical strength. The side-hole fiber is also naturally integrated into a microfluidic system for convenient sample delivery and reduced sample amount. A novel demodulation method based on laser frequency modulation to enhance the sensor dynamic range is proposed and demonstrated.

Nebraska Water Center Annual Report 2015, Nebraska Water Center

Nebraska Water Center: Administrative Materials

Contents

Foreword 4

The Nebraska Water Center: Leadership in Research, Education and Communication 6

Director’s Letter 8

For More Than 50 years: The Nebraska Water Center 10

Helping Build the Future 11

Nebraska Water Center Advisory Board 14

Water Resources Advisory Panel: A key to success 15

Information for Our Clients and the Public 16

Primary Goals 18

USGS 104b Projects 20

Dvorak, Ray Aim at Improving Water Quality for Small Communities 20

October Retreat at UNK 24

Public Water Lectures 25

2015 Special Seminars 26

2015 Water Symposium and Water Law Conference 28

Water Tour Visits Republican River Basin …

2015 Acuta/Nacubo/Acuho-1 Report

ACUTA: Other Publications

In This Issue

Introduction

Methodology

Executive Summary

Findings

Bandwidth Management

Wireless Coverage and Capacity

ResNet Service and Support

Planning and Measurement

Funding and Technology Costs

Outsourcing

Greenhouse Gas Emissions Inventory Of The Centalized Renewable Energy System (Cres) At Nebraska Innovation Campus, Matan Gill, Adam Liska

Adam Liska Papers

The Centralized Renewable Energy System (CRES) at Nebraska Innovation Campus (NIC) is a heat-exchanger system that utilizes reclaimed, non-drinkable water from the nearby water treatment plant to heat and cool a projected 1.675 million square feet of office and lab space. A greenhouse gas emissions inventory was estimated for the CRES operating at full build-out of the campus in 2035, compared to conventional office space, being a control system with standard chiller and boiler configuration. The control system is estimated to emit 30,787 metric tons of carbon dioxide-equivalent per year (Mg CO₂e yr-1), whereas heating and cooling Nebraska …

Higher Education: Opinions And Participation Among Nonmetropolitan Nebraskans: 2015 Nebraska Rural Poll Results, Rebecca J. Vogt, Cheryl A. Burkhart-Kriesel, Randolph L. Cantrell, Bradley Lubben, L. J. Mcelravy

Rural Futures Institute: Publications

Includes

Executive Summary

Introduction

Education or Training Taken

Participation in Education or Training Activities during Past Two Years

Types of Education or Training Taken in Past Two Years

Satisfaction with Types of Education or Training

Satisfaction with Types of Education or Training

Opinions about Education

Flow, Spray Pattern, And Droplet Spectra Characteristics Of An Electronically Actuated Variable-Orifice Nozzle, Joe D. Luck, Santosh Pitla, M. P. Sama, S. A. Shearer

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The purpose of this study was to develop and evaluate the flow rate, spray pattern, and droplet spectra characteristics of an actively controlled variable-orifice nozzle at constant carrier pressures. A commercially available variable- orifice nozzle (VariTarget) was modified to allow for direct electromechanical control of the metering stem. The modified system was tested at five carrier pressures ranging from 138 to 414 kPa and five metering stem (and thus orifice) positions. The metering stem position range was chosen because it provided a linear response in flow rate at each carrier pressure. Flow rate testing indicated a turndown ratio of 2.4:1 …

Accounting For The Short Term Substitution Effects Of Walking And Cycling In Sustainable Transportation, Daniel P. Piatkowski, Kevin J. Krizek, Susan L. Handy

Community and Regional Planning Program: Faculty Scholarly and Creative Activity

The environmental benefits of bicycling and walking depend on the degree to which their use substitutes for car driving. Assuming that every walking and bicycling trip replaces a driving trip is likely to produce overestimates of the potential for such modes to reduce vehicle travel and city-scale greenhouse gas emissions. Measuring this ‘‘substitution effect’’ is not straightforward. There are many dimensions of the substitution effect, including trip type, substituting mode, extent, time horizon, and activity patterns. Previously used approaches to measure substitution include indirect inference and direct questioning. This study piloted an intercept survey using the direct questioning approach at …

Control System Development And Response Analysis Of An Electronically Actuated Variable-Orifice Nozzle For Agricultural Pesticide Applications, Joe D. Luck, S. A. Shearer, M. P. Sama, Santosh Pitla

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The goal of this research project was to further the development of an electromechanically controlled variable-orifice nozzle by creating an electronic control system and then evaluating that system based on step and ramp inputs. The control system was developed in a programming environment that combined an electronic data acquisition system and actuator with pressure and flow sensors. A proportional, variable-gain (based on system pressure) control system was developed to adjust nozzle flow rates to meet target application rates. The constraints were to achieve settling time of less than 1.0 s, overshoot of less than 10% of maximum flow (or minimum …

Ventilation Rates And Airflow Pathways In Patient Rooms: A Case Study Of Bioaerosol Containment And Removal, Ehsan S. Mousavi, Kevin R. Grosskopf

Durham School of Architectural Engineering and Construction: Faculty Publications

Most studies on the transmission of infectious airborne disease have focused on patient room air changes per hour (ACH) and how ACH provides pathogen dilution and removal. The logical but mostly unproven premise is that greater air change rates reduce the concentration of infectious particles and thus, the probability of airborne disease transmission. Recently, a growing body of research suggests pathways between pathogenic source (patient) and control (exhaust) may be the dominant environmental factor. While increases in airborne disease transmission have been associated with ventilation rates below 2 ACH, comparatively less data are available to quantify the benefits of higher …

Adaptive Predictive Functional Controller, Fadi Alsaleem, Arvind Rao

Durham School of Architectural Engineering and Construction: Faculty Publications

A controller device and a method for controlling a system that utilizes an adaptive mechanism to self-learn the system char acteristics and incorporates this adaptive self-learning ability to predict a control parameter correctly to provide precise control of a system component.

An Adaptive Photovoltaic Topology To Overcome Shading Effect In Pv Systems, Mohamed Amer Chaaban, Lana El Chaar, Mahmoud Alahmad

Durham School of Architectural Engineering and Construction: Faculty Publications

Shading in photovoltaic systems can cause many undesired effects.When shading occurs, the power generated from the PV system is much less than nominal power, increasing the electrical mismatching losses between PV system components. Active research to address this power loss focuses on static and adaptive systems.This paper addresses an adaptive system solution and proposes a new method to adaptively overcome losses due to shading during low radiation conditions. In addition, a statistical analysis for choosing the most feasible and efficient configuration for the system size is presented. The proposed system has been validated under shade conditions in a simulation and …

Building Envelope And Interior Grading Systems And Methods, Fadi Mohammad Alsaleem

Durham School of Architectural Engineering and Construction: Faculty Publications

A difference module determines differences between an out door ambient temperature and an indoor temperature, deter mines a first average of the differences, and determines a second average of the differences. A storing module stores a first data point, the first data point including the first average and a first total run time of a heating, ventilation, and/or air conditioning (HVAC) system, and stores a second data point, the second data point including the second average and a second total run time of the HVAC system. A fitting module fits a line to the first and second data points. An …

Relevance Of Blood Vessel Networks In Blast-Induced Traumatic Brain Injury, Yi Hua, Shengmao Lin, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Cerebral vasculature is a complex network that circulates blood through the brain. However, the role of this networking effect in brain dynamics has seldom been inspected. This work is to study the effects of blood vessel networks on dynamic responses of the brain under blast loading. Voronoi tessellations were implemented to represent the network of blood vessels in the brain. The brain dynamics in terms of maximumprincipal strain (MPS), shear strain (SS), and intracranial pressure (ICP) weremonitored and compared. Results show that blood vessel networks significantly affected brain responses.The increased MPS and SS were observed within the brain embedded with …

In Situ Longitudinal Pre-Stretch In The Human Femoropopliteal Artery, Alexey Kamenskiy, Andreas Seas, Grant Bowen, Paul Deegan, Anastasia Desyatova, Nick Bohlim, William Poulson, Jason N. Mactaggart

Department of Mechanical and Materials Engineering: Faculty Publications

In situ longitudinal (axial) pre-stretch (LPS) plays a fundamental role in the mechanics of the femoropopliteal artery (FPA). It conserves energy during pulsation and prevents buckling of the artery during limb movement. We investigated how LPS is affected by demographics and risk factors, and how these patient characteristics associate with the structural and physiologic features of the FPA. LPS was measured in n=148 fresh human FPAs (14–80 years old). Mechanical properties were characterized with biaxial extension and histopathological characteristics were quantified with Verhoeff-Van Gieson Staining. Constitutive modeling was used to calculate physiological stresses and stretches which were then analyzed …

Asphalt Composition, David Allen, Flavio Souza, Yong-Rak Kim, Roberto Soares

Department of Mechanical and Materials Engineering: Faculty Publications

A computational method is provided for predicting roadway failure due to degradation of the roadway over time as a function of the input loads, the roadway geometry, the material properties of the constituents in the asphaltic pavement, the shape, distribution, orientation and volume fractions of the constituents, and environmental conditions. The unique and new feature of the method is that it employs several physically based predictive methodologies simultaneously.

Phase Transformation And Magnetic Properties Of Rapidly Solidified Mn-Al-C Alloys Modified With Zr, Yunlong Geng, Micheal J. Lucis, Pamela Rasmussen, Jeffrey E. Shield

Department of Mechanical and Materials Engineering: Faculty Publications

Mn_54-xAl₄₃C₃Zr_x (x=1, 3) alloys were prepared by rapid solidification followed by heat treatment to produce the ferromagnetic s phase. The substitution of Zr for Mn in the structure resulted in an increase of the saturation magnetization (Ms) compared to that of Mn_54-xAl₄₃C₃. While the highest Ms (12861 emu/g) was obtained in Mn_54-xAl₄₃C₃Zr₁, the coercivity was also improved to 1.62 kOe, compared to 1.25 kOe for Mn_54-xAl₄₃C₃. To further improve the coercivity through grain …

Extracting Continuum-Like Deformation And Stress From Molecular Dynamics Simulations, Lili Zhang, John Jasa, George Gazonas, Antoine Jerusalem, Mehrdad Negahban

Department of Mechanical and Materials Engineering: Faculty Publications

We present methods that use results from molecular dynamics (MD) simulations to construct continuum parameters, such as deformation gradient and Cauchy stress, from all or any part of an MD system. These parameters are based on the idea of minimizing the difference between MD measures for deformation and traction and their continuum counterparts. The procedures should be applicable to non-equilibrium and inhomogeneous systems, and to any part of a system, such as a polymer chain. The resulting procedures provide methods to obtain first and higher order deformation gradients associated with any subset of the MD system, and associated expressions for …