Engineering Commons^™

Pump Controller Design For Variable Primary Flow Configuration Systems, Yifan Shi

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

Pump systems are utilized widely in Heating, Ventilation and Air-Conditioning (HVAC) systems. There are mainly three configuration types: (1) the constant primary-only flow configuration, (2) the constant primary/variable secondary flow configuration, and (3) the variable primary-only flow configuration. This thesis focuses on finding the optimal control strategy for it and programming a controller for easy in-field usage.

In this thesis, the pump brake horse power (BHP) of the three pump configurations is simulated and compared using varying control methods. The best pump efficiency staging and DP reset control methods are implemented into the pump controller. A one month field experiment …

Life-Cycle Assessment Of Nebraska Bridges, George Morcous

Nebraska Department of Transportation: Research Reports

No abstract provided.

Cost-Effective Treatment Of Existing Guardrail Systems, Mitchell J. Wiebelhaus, Karla A. Lechtenberg, Dean L. Sicking, Ronald K. Faller, Scott K. Rosenbaugh

Nebraska Department of Transportation: Research Reports

No abstract provided.

Biomass Gasification: An Alternative Solution To Animal Waste Management, Hanjing Wu

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

The overall goal of this research was to evaluate gasification of animal waste as an alternative manure management strategy, from the standpoints of syngas production and biochar application.

To meet the overall objective, the thermogravimetric characteristics of dairy manure, as a thermochemical conversion feedstock, were studied firstly. Then, gasification technology was applied to dairy manure and feedlot manure using a fluidized-bed laboratory-scale gasifier. In addition, biochar derived from the feedlot manure was examined for its effects on nutrient leaching as a soil amendment. Finally, a life cycle assessment was conducted to evaluate greenhouse gas emissions of two feedlot manure management …

Soil Organic Carbon Dynamics In Agriculture: Model Development And Application From Daily To Decadal Timescales, Matthew P. Pelton

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

Soil carbon (C) is the largest terrestrial C pool globally, containing more C than the atmosphere and biosphere. Soil organic carbon (SOC) is a source and sink of CO₂ emissions to and from the atmosphere, thus influencing future climate change. Understanding SOC dynamics is also important for maintaining C stocks to sustain and improve crop yields. An existing model to estimate changes in SOC due to respiration was modified to operate in three computational platforms: MS Excel, MS Excel with Visual Basic for Applications, and supercomputing. This model was validated against CO₂ flux data from a 9-year field …

Predicting Groundwater Trading Participation In The Upper Republican River Natural Resource District, Elizabeth M. Juchems

Department of Agricultural Economics: Dissertations, Theses, and Student Research

The goal of this thesis is to predict participation in groundwater trading and the directions of trades among participants. Specifically, the paper considers both formal and informal trading of groundwater used for crop irrigation purposes and attempts to identify those characteristics that predict the probability of trade participation and whether an individual is a buyer or seller of groundwater rights. While the public benefits from efficient use of groundwater include adequate stream flow in hydrologically connected areas and future use of groundwater supplies, there are significant private benefits to landowners especially in water-short areas. Groundwater trading can help move water …

Hydraulic Conditions Required To Not Move Unconsolidated Surface Material Located Within Feedlots, John E. Gilley, Gregory D. Boone, David B. Marx

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Beef cattle feedlots contain unconsolidated surface material that accumulates within feedlot pens during a feeding cycle. Runoff from feedlot surfaces is diverted into settling basins. The storage capacity of the settling basins will be substantially reduced if large quantities of solid material are transported in runoff from the feedlot surfaces. The objective of this study was to identify the hydraulic conditions that will not move unconsolidated surface material located within feedlots in order to minimize sediment transport. Selected sizes and a composite sample of unconsolidated surface material were placed within 0.75 m wide by 4.0 m long metal frames. Flow …

Two-Dimensional Blood Flow Velocity Estimation Using Ultrasound Speckle Pattern Dependence On Scan Direction And A-Line Acquisition Velocity, Tiantian Xu, Gregory R. Bashford

Department of Agricultural and Biological Systems Engineering: Faculty Publications

We have previously investigated the change of apparent lateral speckle size caused by the direction and spatial rate of scanner A-line acquisition (scan velocity). An algorithm which measures the lateral component of blood flow velocity was developed based on the increase in speckle size resulting from relative motion between moving scatterers and the scan velocity. In this paper, the change of the apparent dominant angle of the speckle pattern in a straight vessel was investigated and a new method of two-dimensional blood flow velocity estimation is introduced. Different scan velocities were used for data acquisition from blood flow traveling at …

Improving Virtual Collaboration: Modeling For Recommendation Systems In A Classroom Wiki Environment, Derrick A. Lam

School of Computing: Dissertations, Theses, and Student Research

Collaboration is of increased importance in today’s society, with increased emphasis placed on working jointly with others, whether it is in the classroom, in the lab, in the workplace, or virtually across the world. The wiki is one particular virtual collaboration tool that is gaining particular prominence in recent years, enabling people – either in small project groups or as part of the wiki’s entire user base – to socially construct knowledge asynchronously on a wide variety of topics. However, there are few intelligent support tools for wikis available, particularly those providing recommendation-based support to users.

This thesis investigates the …

Design Of Experimental Methods To Test The Performance Of Pads And Helmets Under Blast Loading Conditions, Kurtis Palu

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

Improvised explosive devices (IEDs) have become a primary weapon in conflicts against US and allied forces. Improvements in body armor and medicine have increased the survivability of such events. These factors have caused an increase in traumatic brain injury (TBI) and mild traumatic brain injury (mTBI) induced by primary blast waves. Injury mechanisms caused from primary blast waves are not clearly understood or defined. How primary blast waves interact with materials or between narrow gaps found between helmet pads is not known. Two novel test fixtures were developed to provide a basic understanding of these two issues.

The first fixture …

Precast Concrete Insulated Wall Panel Corbels Without Thermal Bridging, Mohamed Elkady

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

The common practice in corbel design is to block out the insulation in order to provide a solid concrete area at the corbel location. This connection practice results in thermal bridging, which significantly reduces the energy performance of the panel. For example, the PCI Design Handbook indicates that the reduction in thermal resistance caused by a solid part with an area equal to 9% of the total panel surface area is as high as 42%. This paper presents a discussion of a new concept for corbel design of insulated wall panels with the thermal break totally preserved. Two different designs …

Vsfs: A Versatile Searchable File System For Hpc Analytics, Lei Xu, Ziling Huang, Hong Jiang, Lei Tian, David Swanson

School of Computing: Technical Reports

Big-data/HPC analytics applications have urgent needs for file-search services to drastically reduce the scale of the input data to accelerate analytics. Unfortunately, the existing solutions either are poorly scalable for large-scale systems, or lack well-integrated interface to allow applications to easily use them. We propose a distributed searchable file system, VSFS, which provide a novel and flexible POSIX-compatible searchable file system namespace that can be seamlessly integrate with any legacy code without modification. Additionally, to provide real-time indexing and searching performance, VSFS uses DRAM-based distributed consistent hashing ring to manages all file-index. The results of our evaluation show that VSFS …

Fastlane: Flow-Based Channel Assignment In Dense Wireless Networks, Dane N. Seaberg

School of Computing: Dissertations, Theses, and Student Research

Wireless communication in dense networks is becoming more apparent and presents challenges in achieving reliable and near real-time communication. While some works have begun to address dense wireless networks, few address both reliability and latency. In this work we introduce FastLane, a method of ow-based channel assignment for dense wireless networks, which works to achieve reliable, near real-time communication in a dense environment with single-radio devices. FastLane uses an assignment mechanism that assigns channels at a ow-level granularity, rather than a tree-level or link-level granularity. Our scheme also takes into account channel quality and can adapt as the quality changes …

Design And Implementation Of A Hybrid Technology Networking System, Sushanta Mohan Rakshit

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

The safety of rail transport has always been the top priority for the Federal
Railroad Administration (FRA). Legacy technology, like wayside monitoring, is still
in place and is largely relied upon for detection of faults. Modern technology like
Radio Frequency Identification (RFID) has been introduced recently. However, this
is largely used to detect a particular railcar rather than to monitor it for problems.
Wireless Sensor Network (WSN) technology is being evaluated by the railroads for real-time or near real-time monitoring of the status of railcars for timely response to problems and also for trend analysis.

ZigBee has been the networking …

Distributed Multi-Object Tracking With Multi-Camera Systems Composed Of Overlapping And Non-Overlapping Cameras, Youlu Wang

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

Multiple cameras have been used to improve the coverage and accuracy of visual surveillance systems. Nowadays, there are estimated 30 million surveillance cameras deployed in the United States. The large amount of video data generated by cameras necessitate automatic activity analysis, and automatic object detection and tracking are essential steps before any activity/event analysis.

Most work on automatic tracking of objects across multiple camera views has considered systems that rely on a back-end server to process video inputs from multiple cameras. In this dissertation, we propose distributed camera systems in peer-to-peer communication. Each camera in the proposed systems performs object …

Flow And Geometry Measurements At An Active Knickpoint, Clark W. Kephart

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

Channel degradation is an area of growing concern in areas of the Midwestern United States where there are large deposits of loess soils. Channel degradation occurs as a result of disturbances to the sediment load, bed soil configuration, and hydraulic characteristics of the stream (i.e. discharge, channel slope and geometry). These changes may occur suddenly or slowly over time. A given disturbance may be due to a large rain event, channel adjustments (i.e. dredging and straightening), and changes in land use around the stream (Chen et al. 1999).

A knickpoint is an abrupt drop in stream bed elevation over which …

Multi-Objective Time-Cost Optimization Using Cobb-Douglas Production Function And Hybrid Genetic Algorithm, Zhigang Shen, Ashkan Hassani, Qian Shi

Durham School of Architectural Engineering and Construction: Faculty Publications

Existing research on construction time-cost tradeoff issues rarely explore the origin of the crashing cost. Crashing cost function was either assumed without much justification, or came from historical data of some real projects. As a result the conclusions of the papers can hardly be used to guide allocations of labor and equipment resources respectively. The authors believe Cobb-Douglas function provides a much-needed piece to modeling the cost functions in the construction time-cost tradeoff problem during the crashing process. We believe this new perspective fills a gap of existing time-cost tradeoff research by considering project duration, labor and equipment cost as …

Design Of Cable-To-Post Attachments For Use In A Non-Proprietary, High-Tension, Cable Median Barrier, Ryan Joseph Bateman

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

Cable median barriers are widely used across the country to prevent cross-median crashes. Several years ago, the Midwest States Pooled Fund Program contracted with the Midwest Roadside Safety Facility (MwRSF) to develop a new, non-proprietary, high-tension, 4-cable median barrier. In the Fall of 2011 and following two failed full-scale vehicle crash tests on prototype barrier systems, it was determined that design modifications were necessary to improve barrier performance. In addition, members of the Midwest States Pooled Fund Program desired to redirect the development effort.

Both of the barrier system failures which prompted the re-design effort could be partially attributed to …

Formation Of Multiscale Surface Structures On Nickel Via Above Surface Growth And Below Surface Growth Mechanisms Using Femtosecond Laser Pulses, Craig A. Zuhlke, Troy P. Anderson, Dennis R. Alexander

Department of Electrical and Computer Engineering: Faculty Publications

The formation of self-organized micro- and nano-structured surfaces on nickel via both above surface growth (ASG) and below surface growth (BSG) mechanisms using femtosecond laser pulse illumination is reported. Detailed stepped growth experiments demonstrate that conical mound-shaped surface structure development is characterized by a balance of growth mechanisms including scattering from surface structures and geometric effects causing preferential ablation of the valleys, flow of the surface melt, and redeposition of ablated material; all of which are influenced by the laser fluence and the number of laser shots on the sample. BSG-mound formation is dominated by scattering, while ASG-mound formation is …

High-Resolution Correlation Spectroscopy Of 13c Spins Near A Nitrogen-Vacancy Centre In Diamond, Abdelghani Laraoui, Florian Dolde, Christian Burk, Friedemann Reinhard, Jorg Wrachtrup, Carlos A. Meriles

Department of Mechanical and Materials Engineering: Faculty Publications

Spin complexes comprising the nitrogen-vacancy centre and neighbouring spins are being considered as a building block for a new generation of spintronic and quantum information processing devices. As assembling identical spin clusters is difficult, new strategies are being developed to determine individual node structures with the highest precision. Here we use a pulse protocol to monitor the time evolution of the 13C ensemble in the vicinity of a nitrogenvacancy centre. We observe long-lived time correlations in the nuclear spin dynamics, limited by nitrogen-vacancy spin–lattice relaxation. We use the host 14N spin as a quantum register and demonstrate that hyperfine-shifted resonances …

Acuta Enews April 2013 Vol. 42, No. 4

ACUTA Newsletters

In this issue,,,

1 ACUTA Face-to-Face Events

2 ACUTA Alert: FCC Accessibility Rule Certification Requirements

3 News You Can Use- on the Website

4 Sunday Workshops at the Conference

5 Info Links

6 Ten SIP Trunk Equipment License Issues that Can Ruin Your Day (or Month)

8 Board Report

9 Welcome New Members

9 Check It Out

Department Of Biological Systems Engineering Newsletter, Volume 7, Number 2, April 2013

BSE Department Magazine

No abstract provided.

Analysis Of The Feasibility Of Utilizing Wakeup Radios To Optimize Energy And Latency Performance Of Wireless Sensor Networks, Benjamin D. Parks

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

Wireless sensor networks (WSNs) have the potential to radically improve our lives by pervasive environmental monitoring in many applications. However, there are many applications that would be ideal for WSNs, but where reportable events occur with long (days, weeks) or unpredictable durations between occurrences. These uses are hampered by the high energy and latency costs of always-on and periodic wakeup networks, which waste energy on node synchronization and idle monitoring of the RF channel, and exhibit unacceptably high latency for urgent events, e.g., alarms. This thesis proposes, designs, assembles and tests, in a multi-hop WSN test bed, a wakeup receiver …

Energy-Efficient Failure Recovery In Hadoop Cluster, Weiyue Xu

School of Computing: Dissertations, Theses, and Student Research

Based on U.S. Environmental Protection Agency’s estimation, only in U.S., billions of dollars are spent on the electricity cost of data centers each year, and the cost is continually increasing very quickly. Energy efficiency is now used as an important metric for evaluating a computing system. However, saving energy is a big challenge due to many constraints. For example, in one of the most popular distributed processing frameworks, Hadoop, three replicas of each data block are randomly distributed in order to improve performance and fault tolerance, but such a mechanism limits the largest number of machine that can be turned …

Building Upon Common-Pool Resource Theory To Explore Success In Transitioning Water Management Institutions, Christina M. Hoffman

School of Natural Resources: Dissertations, Theses, and Student Research

Nebraska, like many regions around the world, is faced with the challenge of adapting to a new era in water management. Increasing demands for water resources, mounting concerns over threatened and endangered species, and obligations to abide by interstate water allocation agreements have motivated Nebraska to revisit traditional water management approaches. However, although Nebraska’s water management institutions have undergone much change, little research exists on the influence these changes have had on the ability of water institutions to successfully manage water allocations. This research (1) qualitatively explores the perspectives and experiences of stakeholders in the overappropriated region of the Platte …

Thickness-Shear Vibration Of A Rectangular Quartz Plate With Partial Electrodes, Huijing He, Jiashi Yang, John A. Kosinski, Ji Wang

Department of Mechanical and Materials Engineering: Faculty Publications

We study free vibration of a thickness-shear mode crystal resonator of AT-cut quartz. The resonator is a rectangular plate partially and symmetrically electroded at the center with rectangular electrodes. A single-mode, three-dimensional equation governing the thickness-shear displacement is used. A Fourier series solution is obtained. Numerical results calculated from the series show that there exist trapped thickness-shear modes whose vibration is mainly under the electrodes and decays rapidly outside the electrodes. The effects of the electrode size and thickness on the trapped modes are examined.

Mechanics Of Blast Loading On Post-Mortem Human And Surrogate Heads In The Study Of Traumatic Brain Injury (Tbi) Using Experimental And Computational Approaches, Shailesh Govind Ganpule

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

Blast induced neurotrauma (BINT) has been designated as the “signature injury” to warfighters in the recent military conflicts. The occurrence of traumatic brain injury (TBI) in blasts is controversial in the medical and scientific communities because the manifesting symptoms occur without visible injuries. Whether the primary blast waves alone can cause mechanical insult that is comparable to existing traumatic brain injury thresholds is still an open question, and this work is aimed to address this issue.

In the first part of this dissertation, mechanics of primary blast loading on Realistic Explosive Dummy (RED) head with and without helmets is studied …

Distributed Fiber-Optic Laser-Ultrasound Generation Based On Ghost-Mode Of Tilted Fiber Bragg Gratings, Jiajun Tian, Qi Zhang, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

Active ultrasonic testing is widely used for medical diagnosis, material characterization and structural health monitoring. Ultrasonic transducer is a key component in active ultrasonic testing. Due to their many advantages such as small size, light weight, and immunity to electromagnetic interference, fiber-optic ultrasonic transducers are particularly attractive for permanent, embedded applications in active ultrasonic testing for structural health monitoring. However, current fiberoptic transducers only allow effective ultrasound generation at a single location of the fiber end. Here we demonstrate a fiber-optic device that can effectively generate ultrasound at multiple, selected locations along a fiber in a controllable manner based on …

Microfluidic Refractive Index Sensor Based On An All-Silica In-Line Fabry–Perot Interferometer Fabricated With Microstructured Fibers, Jiajun Tian, Yujie Lu, Qi Zhang, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

We report a microfluidic fiber-optic refractive index (RI) sensor based on an in-line Fabry-Perot (FP) interferometer, which is formed by a silica tube sandwiched by two microstructured fibers (MFs). The sensor reported here can be fabricated at low cost, possess a robust structure, and has microfluidic capability. The micro-sized holes in the MFs naturally function as microfluidic channels through which liquid samples can be efficiently and conveniently delivered into and out of the FP cavity by a pressure/vacuum pump system for high-performance RI measurement. Due to the microfluidic capability enabled by the MFs, only sub microliter sample is required. We …

Segmented Nanowires Displaying Locally Controllable Properties, Eli Anguelova Sutter, Peter Werner Sutter

Department of Electrical and Computer Engineering: Faculty Publications

Vapor-liquid-solid growth of nanowires is tailored to achieve complex one-dimensional material geometries using phase diagrams determined for nanoscale materials. Segmented one-dimensional nanowires having constant composition dis play locally variable electronic band structures that are deter mined by the diameter of the nanowires. The unique electrical and optical properties of the segmented nanowires are exploited to form electronic and optoelectronic devices. Using gold-germanium as a model system, in situ transmis sion electron microscopy establishes, for nanometer-sized Au Ge alloy drops at the tips of Ge nanowires (NWs), the parts of the phase diagram that determine their temperature dependent equilibrium composition. The …