Engineering Commons^™

Generic Strategies To Implement Material Grading In Finite Element Methods For Isotropic And Anisotropic Materials, Ke Yu

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

We look at generic strategies to transfer material grading into finite element methods. Three strategies are proposed to transfer material grading into the finite element analysis. These strategies are node-centered, element-centered, and the definition of material grading through external functions. The process to achieve each strategy is stated, and examples are used to illustrate each strategy, and to compare them. The strategies are implemented in finite-deformation nonlinear elastic analysis.

Several examples are used to illustrate the implementation of each strategy for graded isotropic materials. For these examples, the results obtained from finite element models are compared with those obtained from …

Development Of Self-Stressing System For Bridge Application With Emphasis On Precast Panel Deck System, Marcelo Ferreira Da Silva

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

Steel girder bridges often utilize continuity over the pier to reduce interior forces on the spans. In continuous structures with composite concrete decks, the location of maximum negative bending moment is over the interior supports. This moment produces tensile stresses in the concrete deck and compressive stress in the bottom flanges of the girders. The tensile stress in the deck leads to cracking which allow intrusion of moisture and road salt, causing corrosion of the reinforcement and supporting girders. Continued maintenance is required to forestall the deterioration; however, replacement of the deck is eventually required.

To overcome this problem, a …

Determining A Community Retrofit Strategy For The Aging Housing Stock Using Utility And Assessor Data, Nathan A. Barry

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

Residential buildings account for about 21.5% of the nation’s primary energy consumption and carbon emissions, and about 38% of electricity use. The housing stock in the United States consists of over 128 million residences with over 60% being constructed prior to 1979 when building codes and regulations began standardizing building practices. Seeking an opportunity to understand and reduce consumption, the scientific community developed a number of model-driven auditing software. While these computer models have been successful in predicting usage patterns in newer residential structures, they have been inaccurate in predicting and analyzing energy use in aging housing stock, predominantly homes …

Ann Based Load Identification And Forecasting System For The Built Environment, Hosen Hasna

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

"Phantom Loads" cause energy waste in homes and the built environment as a whole. Consumers spend more than $3 billion a year on "Phantom Load" in the United States alone. The goal of this work is to conserve energy by increasing consumer awareness on their energy usage and appropriate tools which in turn will be reducing and /or eliminating phantom loads and mismanagement of the load in the built environment. A further goal is to improve upon existing power distribution systems in the built environment with limited hardware additions to increase energy conservation. This work investigates remote identification of load …

An Rf Cmos Implementation Of An Adaptive Filter For Narrow-Band Interferer Suppression In Uwb Systems, Markus Both

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

Ultra-wideband (UWB) technology is a new type of technology for wireless communication that is based on the transmission of low power sub-nanosecond pulses. UWB communication utilizes a large bandwidth that overlaps and is coexistent with other wireless communication standards that can be also considered as narrow-band interferers. Because UWB systems are highly susceptible to narrow-band interferers, there is a demand for interferer suppression. An adaptive filter consisting of a two-element diversity receiver that performs minimum mean square error combining (MMSE) by the LMS algorithm is proposed. Thereby the elements of the LMS algorithm as well as the receiver LNA were …

A Study Of Correlations Between The Definition And Application Of The Gene Ontology, Yuji Mo

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

When using the Gene Ontology (GO), nucleotide and amino acid sequences are annotated by terms in a structured and controlled vocabulary organized into relational graphs. The usage of the vocabulary (GO terms) in the annotation of these sequences may diverge from the relations defined in the ontology. We measure the consistency of the use of GO terms by comparing GO's defined structure to the terms' application. To do this, we first use synthetic data with different characteristics to understand how these characteristics influence the correlation values determined by various similarity measures. Using these results as a baseline, we found that …

Virtual Microstructure Generation Of Asphaltic Mixtures, Mohammad Haft-Javaherian

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

This thesis describes the development and application of a virtual microstructure generator incorporated with post-processing image analysis methods that can be used to fabricate a virtual, two-dimensional microstructure of asphaltic mixtures. In the generator, geometrical characteristics such as aggregate gradation, aggregate area fraction, angularity, orientation, and elongation were used to transform data from a three-dimensional (3D) mixture into its two-dimensional (2D) microstructure. The 2D virtual microstructures were generated from real 3D mixture information of asphaltic composites. Resulting virtual microstructures were then compared to real cross-sectional microstructure images obtained from actual samples for validation. Comparison presented a good agreement between the …

Highly Efficient Maximum Power Point Tracking Using A Quasi-Double-Boost Dc/Dc Converter For Photovoltaic Systems, Christopher J. Lohmeier

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

Solar photovoltaic (PV) panels are a great source of renewable energy generation. The biggest problem with solar systems is relatively low efficiency and high cost. This work hopes to alleviate this problem by using novel power electronic converter and control designs. An electronic DC/DC converter, called “Quasi-Double-Boost DC/DC Converter,” is designed for a Solar PV system. A Maximum Power Point Tracking (MTTP) algorithm is implemented through this converter. This algorithm allows the PV system to work at its highest efficiency. Different current sensing and sensorless technologies used with the converter for the MPPT algorithm are offered and tested. Design aspects …

Effect Of Extracellular Matrix (Ecm) Protein Micropatterns On The Behavior Of Human Neuroblastoma Cells, Ishwari Poudel

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

Recent advances in patterning techniques and emerging surface microtechnologies have allowed cell micropatterning to control spatial location of the cells on a surface as well as cell shape, attachment area, and number of contacting neighbor cells. These parameters play important roles in cell cellular behaviors. Cell micropatterning has thus become one of the most important strategies for biomedical applications, such as, tissue engineering, diagnostic immunoassays, lab-on-chip devices, bio-sensing, etc., and cell biology studies as well. For neuronal cells, there have been attempts to distribute neuronal cells on specific patterns to control cell-to-cell interaction. However, there have been very limited understanding …

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Studies On Power Hop Using A Nonlinear Model Of An Agricultural Tractor, Adam B. Flaugh

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

Power hop is an unstable dynamic phenomenon that is observed on agricultural tractors operating at field working speeds under typical draft loads. This dynamic instability can be identified as a bounce motion preceded by an increasing oscillation in either the pitch or bounce modes. A definite and comprehensive correction or prevention strategy for the control of power hop does not exist. In this work a linear and a nonlinear model of an agricultural tractor were developed. The method of multiple time scales has been employed in the analysis of the nonlinear model. Numerical results have been obtained using Mathematica to …

Evaluating The Cost-Effectiveness Of Roadside Culvert Treatments, Francisco Daniel B. De Albuquerque, Dean L. Sicking, Ronald K. Faller, Karla A. Lechtenberg

Department of Civil and Environmental Engineering: Faculty Publications

Roadside cross-drainage culverts have been found to affect vehicle accident injury levels. As a result, highway designers have commonly used three safety treatments to protect errant motorists from striking culvert openings. These safety treatments have included: culvert extension, guardrail installation, and the application of safety grating. However, the identification of the most appropriate safety treatment for roadside culverts may be challenging; accident costs may dramatically change under different road and traffic characteristics. The purpose of this study was to estimate accident costs for a wide range of road and traffic scenarios and then define the safest treatment (i.e., treatment with …

A General Attack Method For Steganography Removal Using Pseudo-Cfa Re-Interpolation, Pradhumna Shrestha, Michael Hempel, Tao Ma, Dongming Peng, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Watermarking and steganography are two of the most researched topics in multimedia forensics. However, easy availability of tools and technology has made their misuse a serious concern. To counteract this development some effective tools are necessary to remove malicious steganography. In this work, we introduce a novel watermark attack method which can destroy hidden information embedded in images based on the principle of re-interpolation of Color Filter Array (CFA) artifacts. In digital cameras and scanners, CFA filters are used to acquire low-resolution physical color channel information and produce a high-quality image by subsequent interpolation. We propose to emulate a similar …

Evaluation Of The In-Service Safety Performance Of Safety-Shape And Vertical Concrete Barriers, Francisco Daniel Benicio De Albuquerque, Dean L. Sicking

Nebraska Department of Transportation: Research Reports

No abstract provided.

Water Quality Models For Stormwater Runoff In Two Lincoln, Nebraska Urban Watersheds, Jake Fisher

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

Water quality monitoring was conducted in two urban watersheds (Colonial Hills and Taylor Park) located in southeast Lincoln, NE over a three year period spanning from October 2008 through September 2011. In-line probes continuously measured for turbidity, conductivity, dissolved oxygen, and water temperature while other water quality constituents were analyzed for discrete water samples collected using grab and automatic sampling techniques. The water quality data was used to calculate event mean concentrations (EMCs) for sixteen storm events sampled over the duration of the project period. Three types of stormwater quality multiple linear regression models were developed for the estimation of …

Evaluation Of Ndor's Actuated Advance Warning Systems, Justice Appiah, Laurence Rilett, Zifeng Wu

Nebraska Department of Transportation: Research Reports

No abstract provided.

Phase I Development Of A Non-Proprietary, Four-Cable, High Tension Median Barrier, Mitchell J. Wiebelhaus, Dean L. Sicking, Ronald K. Faller, Karla A. Lechtenberg, John R. Rohde, Robert W. Bielenberg, Scott Rosenbaugh, Erin A. Johnson, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

The Effects Of Pedestrian Countdown Timers On Safety And Efficiency Of Operations At Signalized Inersections, Anuj Sharma, Jacob Schmitz

Nebraska Department of Transportation: Research Reports

No abstract provided.

Development Of A State Of The Art Traffic Microsimulation Model For Nebraska, Justice Appiah, Bhaven Naik, Laurence Rilett, Yifeng Chen, Seung-Jun Kim

Nebraska Department of Transportation: Research Reports

No abstract provided.

The Economics And Logistics Of The Dual Harvest Of Grain And Biomass In A Single-Pass, Matthew T. Wold

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

Significant interest has developed in using cellulosic resources, especially crop residues, to create biofuels. Collecting these residues in a single-pass of the harvester across the field has the potential to be a low cost option. Two models have been developed; the first characterizes the in-field logistics of single-pass crop residue collection, the second the economics. These models allow the user to easily examine a wide variety of both grain-only and single-pass residue collection harvest cases. A variety of possible residue collection cases have been examined, and their effects both on harvester field capacity and harvest cost compared to grain-only harvest …

Feasibility Analysis And Concept Development Of A Crash Cushion Diaphragm Structure For High-Speed Race Tracks, Curt Lee Meyer

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

A new diaphragm and dual guide rail system was designed for use in a crash cushion for high-speed race tracks. These structural components were designed to provide sufficient lateral support to redirect impacting vehicles and compress the energy-absorbing elements of the crash cushion. The primary design criteria stated that the diaphragm/guide rail system should be capable of withstanding a 100-kip lateral impact load. The guide rail was to be configured in order to not require replacement after a design impact event. Initial design and modeling resulted in two candidates for guide rail sections which were evaluated during physical testing. The …

A Novel Telecommunications-Based Approach To Mathematical Modeling Of Hiv Infection, Aaron T. Sharp

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

It is well known that biological systems utilize communication in some form, one prolific example of this is the propagation of HIV (Human Immunodeficiency Virus) in the human body. By modeling HIV infection as a communication system, we hope to gain a unique insight into HIV and biological communication systems in general. Such a model would provide researchers a platform for experimenting and simulating various biological communication systems. We have previously developed a layered communication protocol for interpreting biological communication systems using telecommunications paradigms and will apply said model to HIV proliferation. We will also demonstrate the effectiveness of the …

Expanding The Length Of Jointless Bridges By Providing Rotational Capacity Over The Pile Head, Ardalan Sherafati

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

Jointless bridges have been in service for more than 50 years. Since no expansion joint is utilized in these structures, they have longer service life, reduced maintenance and construction costs, improved riding quality, and added redundancy. Because of integrity of the superstructure with the substructure, the thermal movements as well as other longitudinal movements are transferred to substructure. These lateral movements can induce relatively large forces and moments in the substructure elements including the abutment and the piles. Typically, flexible foundations which include single row of piles are preferred in jointless bridges to reduce the stiffness of the system against …

Ethnic Difference In Healthcare Delivery, Benny Mathew Varghese

Department of Industrial and Management Systems Engineering: Dissertations, Theses, and Student Research

Quality in healthcare is a very important aspect; this is obtained when there is proper care provided to the patients without any discrimination. The healthcare system in the US can be improved in the fields of patient’s care, the amount of money spent and proper advice, if proper responsibilities are taken. Quality has been improving over the years, but the median by which there is an increase is too small. The other main factor is access to the healthcare system, which has over the year, has not progressed. Studies in healthcare quality should be conducted on a regular base, so …

Location Cheating: A Security Challenge To Location-Based Social Network Services, Mai Ren

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

Location-based mobile social network services such as Foursquare and Gowalla have grown exponentially over the past several years. These location-based services utilize the geographical position to enrich user experiences in a variety of contexts, including location-based searching and location-based mobile advertising. To attract more users, the location-based mobile social network services provide real-world rewards to the user, when a user checks in at a certain venue or location. This gives incentives for users to cheat on their locations.

In this thesis, we investigate the threat of location cheating attacks, find the root cause of the vulnerability, and outline the possible …

Water Quality Monitoring Of An Urban Stream For Total Maximum Daily Load Assessment, Jeffrey K. Mihulka

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

The purpose of this research project was to assess the water quality of an urban stream for total maximum daily load assessment in Omaha, Nebraska. This was accomplished by sampling the water quality at four different sites. These sites included sampling upstream, within, and downstream of the city. These samples were conducted throughout 2010 and 2011.

The results showed that concentrations of Escherichia coli (E. coli) are routinely above established criteria for the state of Nebraska. Concentrations of E. coli that exist in the Papillion Creek Watershed upstream of the City of Omaha have also been shown to be above …

Nanoparticle Necklace Network Arrays Exhibiting Room Temperature Single-Electron Switching, Jennifer L. Kane

Department of Chemical and Biomolecular Engineering: Theses and Student Research

A single nanoparticle is one of the most sensitive electronic devices for sensing chemicals in a gas or liquid. The conductivity of a single Au nanoparticle is significantly modulated by the binding of a molecule that alters charge by just one electron. However, the single-electron sensitivity requires cryogenic temperatures and interconnection is not easy. A patterned two-dimensional network of one-dimensional nanoparticle necklaces made up of 10 nm Au particles are fabricated and shown to exhibit similar single-electron effect at room temperature. Furthermore, the long range conductivity of over 10’s of microns makes the structure easy to self-assemble onto conventional microelectronics …

Relational Neighborhood Inverse Consistency For Constraint Satisfaction: A Structure-Based Approach For Adjusting Consistency & Managing Propagation, Robert J. Woodward

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

Freuder and Elfe [1996] introduced Neighborhood Inverse Consistency (NIC) as a local consistency property defined on the values in the variables' domains of a Constraint Satisfaction Problem (CSP). Debruyne and Bessiere [2011] showed that enforcing NIC on binary CSPs is ineffective on sparse graph and too costly on dense graphs. In this thesis, we propose Relational Neighborhood Inverse Consistency (RNIC), an extension of NIC defined as a local consistency property on the tuples of the relations of a CSP. We characterize RNIC for both binary and non-binary CSPs, and propose an algorithm for enforcing it whose complexity is bounded by …

Sensitivity Analysis On Mapping Evapotranspiration At High Resolution Using Internal Calibration (Metric), Venkata Naga Ravi Kumar Choragudi

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

Mapping EvapoTranspiration at high Resolution using Internal Calibration (METRIC) is most widely used to quantify evapotranspiration (ET) spatially and temporally. It is essential to inspect the model’s response to errors in various parameters used in the model. Landsat 5 images from May 30 2009, July 1 2009 and a Landsat 7 image from September 27 2009 are used in this study. Fourteen different fields composed of Corn, Soybeans, Alfalfa are randomly chosen for each crop type.

Two kinds of errors are addressed in this study. One, with the errors that are transferred and potentially compensated by calibration (Global error) and …

Development Of A Design Procedure For Concrete Traffic Barrier Attachments To Bridge Decks Utilizing Epoxy Concrete Anchors, Benjamin J. Dickey

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

A guide for the design of epoxy anchors for the use in concrete traffic barriers was developed in this study. A series of dynamic bogie tests and static tests was conducted on single and double anchors. The dynamic increase factor for the noted anchors was determined to be 1.06. Protective epoxy coatings for the anchors was observed to contribute to a 9 percent decrease in anchorage strength. The effects of anchors located in close proximity to each other was also investigated. Calibration factors were developed to apply recommended changes to the ACI code for use in bridge rail anchorages.

A …