Engineering Commons^™

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 …

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 …

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 …

On Problematic Robotic Thresholds, Adam K. Taylor

Department of Computer Science and Engineering: 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” …

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 …

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 …

On Reliability Of Smart Grid Neighborhood Area Networks, Shengjie Xu, Yi Qian, Rose Qingyang Hu

Department of Electrical and Computer Engineering: Faculty Publications

With the integration of the advanced computing and communication technologies, smart grid system is dedicated to enhance the efficiency and the reliability of future power systems greatly through renewable energy resources, as well as distributed communication intelligence and demand response. Along with advanced features of smart grid, the reliability of smart grid communication system emerges to be a critical issue, since millions of smart devices are interconnected through communication networks throughout critical power facilities, which has an immediate and direct impact on the reliability of the entire power infrastructure. In this paper, we present a comprehensive survey of reliability issues …

Fuel Consumption Models For Tractors With Partial Drawbar Loads, Bryan Jeffrey Smith

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

Three models for predicting fuel consumption for agricultural tractors with partial drawbar loads were compared. Data were collected from eight John Deere tractors, JD 7230R (e23), 7250R (e23), 7270R (e23), 7290R (e23), 7290R (IVT), 8320R (16 speed), 8345RT (IVT), 8370R (IVT). The tractors were tested with 7 load levels per speed at four different travel speeds as close as possible to 4, 7.5, 10, and 13 km·h^-1. The IVT tractors were operated in Auto mode and the geared tractors were shifted up three gears and throttled back to the same travel speeds as the IVT tractors. The 7 …

Background Differences In Baseline And Stimulated Mmp Levels Influence Abdominal Aortic Aneurysm Susceptibility, Matthew A. Dale, Melissa K. Suh, Shijia Zhao, Trevor Meisinger, Linxia Gu, Vicki J. Swier, Devendra K. Agrawal, Timothy Greiner, Jeffrey S. Carson, B. Timothy Baxter, Wanfen Xiong

Department of Mechanical and Materials Engineering: Faculty Publications

Objective: Evidence has demonstrated profound influence of genetic background on cardiovascular phenotypes. Murine models in Marfan syndrome (MFS) have shown that genetic background-related variations affect thoracic aortic aneurysm formation, rupture, and lifespan of mice. MFS mice with C57Bl/6 genetic background are less susceptible to aneurysm formation compared to the 129/SvEv genetic background. In this study, we hypothesize that susceptibility to abdominal aortic aneurysm (AAA) will be increased in 129/SvEv mice versus C57Bl/6 mice. We tested this hypothesis by assessing differences in aneurysm size, tissue properties, immune response, and MMP expression.

Methods: Mice of C57Bl/6 or 129/SvEv background underwent AAA induction …

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 …

Development Of A Semicircular Bend (Scb) Test Method For Performance Testing Of Nebraska Asphalt Mixtures, Gabriel Nsengiyumva, Yong-Rak Kim, Taesun You

Nebraska Department of Transportation: Research Reports

No abstract provided.

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 …

Feasibility Of Using Raman-Based Techniques For Breast Cancer Detection, Sara Mollamohammada

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

Breast cancer is one of the common types of cancer among women all over the world. Early diagnosis is an effective way that improve the treatment process and gives the patients a better chance of survival. Many of the patients infected by breast cancer choose breast conservation surgery (BCS). However, some of those will be subjected to mastectomy, and many will have tumor recurrence as there is no precise technique to show the tumor margins. Raman-based methods are powerful techniques with potential to rapidly differentiate normal from tumor tissues and provides a solution to detect tumor margin. This is because …

Nebraska Data Collection, Keyvan Zare Rami, Yong-Rak Kim

Nebraska Department of Transportation: Research Reports

Automated pavement performance data collection is a method that uses advanced technology to collect detailed road surface distress information at traffic speed. Agencies are driven to use automated survey techniques to enhance or replace their current manual distress survey because of the advantages of objective measurements, safety benefits, and reduced measurement time. As agencies move toward the transition to fully automated data collection methods, there are common concerns regarding how the output of the new method will match the current manual survey ratings and how they will be adopted into the existing Pavement Management System (PMS). This study evaluates the …

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 …

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

Department of Chemical and Biomolecular Engineering: 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 …

Microstructure Alone Induced Wetting Transition From Hydrophilic To Hydrophobic On Silicon And Graphene, Henry L. Ems

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

In the present work, transition from hydrophilic to hydrophobic wetting states for an intrinsically hydrophilic surface (contact angle less than 45 degrees) using only surface microstructuring is presented. The surface microstructures are re-entrant microcavities (inverted trapezoidal microstructures) which promote air entrapment below the water droplet causing a Cassie wetting state as opposed to a Wenzel state where the surface is completely wetted. The microstructures were fabricated on a Silicon-On-Insulator (SOI) wafer through steps of deposition, photolithography, etching, and bonding. Contact angle measurements demonstrated the ability of the microfabricated surfaces to sustain large contact angles above 100°, in comparison to a …

Experimental Investigation And Thermal Modeling On Electro Discharge Drilling Of Pcd, Farnaz Nourbakhsh

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

This study presents an experimental investigation and finite element simulation of Electro Discharge Drilling (ED-Drilling) of Polycrystalline Diamond (PCD). PCD has many outstanding properties including uniformly high hardness, high wear resistance and strong corrosion which are the main causes of widely using PCD. While PCD has many advantages and an important role in industrial applications, its high level of hardness and wear resistance cause this material to be difficult to form and machine by using traditional machining methods. EDM as a nontraditional machining process is an effective method among other non-traditional methods for PCDs due to its low cost and …

Subjective Perception Of Varying Reflection Densities In Room Impulse Responses, Hyun Hong

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

Reverberation time (RT) is a metric commonly used to describe room acoustic conditions, but different rooms which have the same reverberation time can have different reflection densities. Much less is known about how humans perceive different reflection densities and how sensitive humans are to changes in reflection density. Previous investigations in the existing literature have studied the upper limit of distinguishable reflection density using artificial impulse responses, but not with more realistic impulse responses simulated in room acoustic software or measured from real rooms. The aim of this dissertation is to investigate methods for quantifying reflection density from measured impulse …

Methodology For Selecting The Column Configuration With Lowest Media Replacement Cost For Small Adsorption Systems, Artem Bausk

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

The relative performance of three column configurations often used for adsorption systems serving small communities was evaluated in terms of which results in the lowest overall replacement cost. Replacement cost is the cost of fresh media and the transportation, labor, and material costs to replace the media. Both the adsorption capacity and the media replacement costs were modeled. The pore and surface diffusion model was utilized to simulate the fixed-bed adsorption and obtain the breakthrough curves, which were then normalized using the target effluent to influent concentration ratio (C/C_o) and the mass transfer zone fraction (%MTZ_BT). …

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 …

Phase I Evaluation Of Selected Concrete Material Models In Ls-Dyna, Bradley J. Winkelbauer

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

Numerous roadside safety systems are configured with reinforced concrete materials, such as bridge railings, median barriers, and roadside parapets. These protective barrier systems are intended to safely contain and redirect errant vehicles as well as prevent impacts into hazardous fixed objects or other geometric features. The analysis and design of these structures may involve impact simulation with finite element software, like LS-DYNA, which includes multiple concrete material models. For such investigations, limited guidance is available for selecting preferred concrete material models and determining appropriate values for specific parameters. This Phase I study investigated the viability and performance of existing concrete …

Transforming C Openmp Programs For Verification In Civl, Michael Rogers

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

There are numerous way to express parallelism which can make it challenging for developers to verify these programs. Many tools only target a single dialect but the Concurrency Intermediate Verification Language (CIVL) targets MPI, Pthreads, and CUDA. CIVL provides a general concurrency model that can represent pro- grams in a variety of concurrency dialects. CIVL includes a front-end that support all of the dialects mentioned above. The back-end is a verifier that uses model checking and symbolic execution to check standard properties.

In this thesis, we have designed and implemented a transformer that will take C OpenMP programs and transform …

Bandwidth Estimation For Virtual Networks, Ertong Zhang

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

Cloud computing is transforming a large part of IT industry, as evidenced by the increasing popularity of public cloud computingservices, such as Amazon Web Service, Google Cloud Platform, Microsoft Windows Azure, and Rackspace Public Cloud. Manycloud computing applications are bandwidth-intensive, and thus the network bandwidth information of clouds is important for theirusers to manage and troubleshoot the application performance.

The current bandwidth estimation methods originally developed for the traditional Internet, however, face great challenges in clouds dueto virtualization that is the main enabling technique of cloud computing. First, virtual machine scheduling, which is an importantcomponent of computer virtualization for processor …

Using Software-Defined Networking To Improve Campus, Transport And Future Internet Architectures, Adrian Lara

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

Software-defined Networking (SDN) promises to redefine the future of networking. Indeed, SDN-based networks have unique capabilities such as centralized control, flow abstraction, dynamic updating of forwarding rules and software-based traffic analysis. SDN-based networks decouple the data plane from the control plane, migrating the latter to a software controller. By adding a software layer between network devices and applications, features such as network virtualization and automated management are simpler to achieve.

In this dissertation, we show how SDN-based deployments simplify network management at multiple scales such as campus and transport networks, as well as future Internet architectures. First, we propose OpenSec, …

Information Seeking Behaviour Of Petroleum Engineers In Niger Delta Region Of Nigeria: A Survey, Edonkumoh Victor Ebiye (Mlis), Ngwuchukwu M. N (Phd), Emmanuel Agyo (Mlis)

Library Philosophy and Practice (e-journal)

The success of the petroleum industry at all levels depend largely on petroleum engineers’ awareness and access to relevant information for making sound Exploration and Production decisions. This study investigated the information seeking behaviour of Petroleum Engineers in selected companies in the Niger Delta Region of Nigeria. A survey design was adopted using questionnaire as the instrument for collecting primary data from 250 petroleum engineers randomly selected from four oil companies. Data gathered were analysed using frequencies, simple percentages and mean score count. Results showed that petroleum engineers spent time seeking health and safety information, oil and gas E&P information, …

Imaging Thermal Conductivity With Nanoscale Resolution Using A Scanning Spin Probe, Abdelghani Laraoui, Halley Aycock-Rizzo, Yang Gao, Xi Lu, Elisa Riedo, Carlos A. Meriles

Department of Mechanical and Materials Engineering: Faculty Publications

The ability to probe nanoscale heat flow in a material is often limited by lack of spatial resolution. Here, we use a diamond-nanocrystal-hosted nitrogen-vacancy centre attached to the apex of a silicon thermal tip as a local temperature sensor. We apply an electrical current to heat up the tip and rely on the nitrogen vacancy to monitor the thermal changes the tip experiences as it is brought into contact with surfaces of varying thermal conductivity. By combining atomic force and confocal microscopy, we image phantom microstructures with nanoscale resolution, and attain excellent agreement between the thermal conductivity and topographic maps. …

Volatile Condensible Material Deposition In Leo Simulated Environment, Jinya Pu

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

Room Temperature Vulcanized (RTV) silicone and compounds are widely used in outer-space for bonding or potting spacecraft components. In geosynchronous equatorial orbit (GEO), the silicone may outgas species which can condense on optically sensitive surfaces and degrade their performance, therefore shortening the lifetime of spacecraft. In low-earth-orbit (LEO), the silicone rubber is subject to an energetic and corrosive environment. Atomic oxygen (AO) and ultraviolet radiation can cause abrasion and degradation of the silicone rubber, cause changes in existing condensed VCM films and affect the properties of VCM films condensing in this atmosphere. Experiments were performed to simulate GEO conditions. In …

Spatial Domain Management And Massive Mimo Coordination In 5g Sdn, Songlin Sun, Bo Rong, Rose Qingyang Hu, Yi Qian

Department of Electrical and Computer Engineering: Faculty Publications

In 5G mobile communication systems, massive multiple-input multiple-output (MIMO) and heterogeneous networks (HetNets) play crucial roles to achieve expected coverage and capacity across venues. This paper correspondingly addresses software-defined network (SDN) as the central controller of radio resource management in massive MIMO HetNets. In particular, we identify the huge spatial domain information management and complicated MIMO coordination as the grand challenges in 5G systems. Our work accordingly distinguishes itself by considering more network MIMO aspects, including flexibility and complexity of spatial coordination. In our proposed scheme, SDN controller first collects the user channel state information in an effective way, and …