Engineering Commons^™

Development And Recommendation For A Non-Proprietary, High-Tension, Cable End Terminal System, Ryan J. Terpsma, Ronald K. Faller, Dean L. Sicking, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

Test Matrices For Evaluating Cable Median Barriers Placed In V-Ditches, Ronald K. Faller, Scott K. Rosenbaugh, Mario Mongiardini, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

Corrosion Assessment Of Cast Aluminum Parts In Ethanol Fuel Blends, P. Wirot, J. Troset, W. Khonraeng, S. Mahabunphachai, E. Viyanit

Journal of Metals, Materials and Minerals

Nowadays, the use of ethanol fuel blends in automobiles has become more and more worldwide since the ethanol mixture would enhance the performance of the engine and fuel economy ($/mile), while reducing the hazardous exhaust released to the environment. However, the use of ethanol fuel blends may induce some material compatibility issues on some automotive parts that were not designed to be used in contact with ethanol. In other words, the humidity in the ethanol would cause corrosion problem on these parts. The goal of this study is to assess the corrosion value of two cast aluminum parts in a …

Incorporating Memory And Learning Mechanisms Into Meta-Raps, Arif Arin

Engineering Management & Systems Engineering Theses & Dissertations

Due to the rapid increase of dimensions and complexity of real life problems, it has become more difficult to find optimal solutions using only exact mathematical methods. The need to find near-optimal solutions in an acceptable amount of time is a challenge when developing more sophisticated approaches. A proper answer to this challenge can be through the implementation of metaheuristic approaches. However, a more powerful answer might be reached by incorporating intelligence into metaheuristics.

Meta-RaPS (Metaheuristic for Randomized Priority Search) is a metaheuristic that creates high quality solutions for discrete optimization problems. It is proposed that incorporating memory and learning …

Modeling, Identification, Validation And Control Of A Hybrid Maglev Ball System, Ahmed Elhussein E. Mekky

Mechanical & Aerospace Engineering Theses & Dissertations

In this thesis, the electrodynamics of a single axis hybrid electromagnetic suspension Maglev system was modeled and validated by applying it to a single axis hybrid maglev ball experiment. By exploring its linearized model, it was shown that the single axis hybrid Maglev ball has inherently unstable dynamics. Three control scenarios were explored based on the linearized model; (1) Proportional, Deferential (PD) control, (2) Proportional, Deferential, Integral (PID) and (3) PID controller with pre-filtering. This thesis has shown that a PID controller with a pre-filtering technique can stabilize such a system and provide a well-controlled response.

A parametric system identification …

Response Surface Optimization Of Electron Beam Freeform Fabrication Depositions Using Design Of Experiments, Patricia A. Quigley

Engineering Management & Systems Engineering Theses & Dissertations

The Electron Beam Freeform Fabrication (EBF³ ) System is a material depositing, layer additive technique that produces three dimensional (3D) parts out of a wide range of metals in high vacuum, using an electron beam and wire feedstock. Screening deposition trials on a titanium alloy, Ti-6Al-4V, at the National Aeronautics Space Administration (NASA) revealed selective vaporization of the aluminum content of linear prototypes when subjected to chemical analysis. In this study, the aluminum content, bead height and bead width output responses were analyzed from a systematic study of the effects that the interactions of the EBF³ processing parameters …

Synthesis Of A Superlattice Structure Of Alternating Layers Of Antimony Telluride And Bismuth Telluride By Atomic Layer Deposition For Thermoelectric Applications, David Nminibapiel

Electrical & Computer Engineering Theses & Dissertations

Alloys composed of bismuth, antimony and telluride compounds exhibit very high figure of merit ZT values at relatively low temperatures, making them exceptional thermoelectric materials. Advancement in thermoelectric devices and applications hinges on increasing ZT, which is a ratio of the thermoelectric power factor to the thermal conductivity. One of the proposed avenues to achieving this goal is the use of low dimensional structures such as quantum wells, quantum dots, superlattices (SL) and nanolaminates to affect heat transport. SL structures can effectively confine charge carriers as well as scatter phonons which contribute significantly to thermal conductivity. In this thesis, the …

Numerical Analysis And Design Optimization Of Organic Bulk Hetero-Junction Solar Cells Using The Mixed Finite Element And Arc-Length Methods, James L. Dean

Mechanical & Aerospace Engineering Theses & Dissertations

Due to the high coupling and non-linear nature of the semiconductor equations, numerical stability becomes a major problem when using a purely Newtonian numerical method in solving these equations. Presented is a robust mixed finite element formulation with application for organic solar cell devices that incorporates the arc-length predictor-corrector method to bypass such stability issues. The simulated device represents a multilayered solar cell using organic bulk hetero-junction materials including donor materials Poly[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4- b']dithiophene-2,6-diyl]] (PCPDTBT) and poly 3-hexylthiophene (P3HT) with acceptor fullerene materials [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) or [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) as the photoactive …

Dynamic Model Of Sailors Descending A Navy Ship Ladder, Jonathan Coulter

Mechanical & Aerospace Engineering Theses & Dissertations

Knee moments are greater in individuals who climb Navy ship ladders than in people climbing stairs. Because it is known that people who climb stairs frequently are at greater risk for osteoarthritis and that people in the Navy report higher incidences of knee pain, it was hypothesized that the internal joint reaction forces during the sailor's descent of a ship ladder would be greater than internal joint reaction forces of gait and stair climbing. Dimensions of a commonly used Navy ship ladder were collected and a replica was constructed. The replica was instrumented to collect 3D kinematics and kinetics during …

Development And Validation Methodology Of The Nuss Procedure Surgical Planner, Krzysztof J. Rechowicz

Computational Modeling & Simulation Engineering Theses & Dissertations

Pectus excavatum (PE) is a congenital chest wall deformity which is characterized, in most cases, by a deep depression of the sternum. A minimally invasive technique for the repair of PE (MIRPE), often referred to as the Nuss procedure, has been proven to be more advantageous than many other PE treatment techniques. The Nuss procedure consists of placement of a metal bar(s) underneath the sternum, thereby forcibly changing the geometry of the ribcage. Because of the prevalence of PE and the popularity of the Nuss procedure, the demand to perform this surgery is greater than ever. Therefore, a Nuss procedure …

Towards Managing And Understanding The Risk Of Underwater Terrorism, Richard J. Gay

Engineering Management & Systems Engineering Theses & Dissertations

This dissertation proposes a methodology to manage and understand the risk of underwater terrorism to critical infrastructures utilizing the parameters of the risk equation. Current methods frequently rely on statistical methods, which suffer from a lack of appropriate historical data to produce distributions and do not integrate epistemic uncertainty. Other methods rely on locating subject matter experts who can provide judgment and then undertaking an associated validation of these judgments.

Using experimentation, data from unclassified successful, or near successful, underwater attacks are analyzed and instantiated as a network graph with the key characteristics of the risk of terrorism represented as …

Establishing Relationships Between Risk Management And Knowledge Transfer, Garrett S. Haltiwanger

Engineering Management & Systems Engineering Theses & Dissertations

Risk management (RM) and Knowledge management (KM) have mostly been treated as separate management philosophies. Risk management is a widely taught topic in academia and is practiced in industry. Knowledge management is being taught at increasingly more colleges and many companies are discovering a need for managing knowledge. This dissertation shows that some research has been conducted to apply the principles of knowledge management in establishing risk management plans. To a lesser extent there has been research conducted to apply the philosophies of risk management to identifying knowledge gaps and maintaining corporate knowledge. Both risk management and knowledge management are …

Diamond This Film Patterning Technique Using Selective Nucleation Growth, Characterization And Application, Weican Xiao

Electrical & Computer Engineering Theses & Dissertations

Diamond is the hardest bulk material with the highest thermal conductivity. It is also an excellent wide band gap material; hence, diamond is suitable for electronic, mechanical and biological applications. Unfortunately, natural diamond is prohibitively expensive for most technological applications. Polycrystalline diamond, with properties close to those of natural diamond, has been synthesized since the 1950s. Among many methods employed for diamond thin film synthesis, chemical vapor deposition (CVD) using microwave plasma (MW) is quite popular for several reasons. Well-confined plasma that does not touch the reaction chamber walls can be produced directly on the substrate. Hence, contamination in the …

Application Of Chebyshev Formalism To Identify Nonlinear Magnetic Field Components In Beam Transport System, Michael Spata

Physics Theses & Dissertations

An experiment was conducted at Jefferson Lab's Continuous Electron Beam Accelerator Facility to develop a beam-based technique for characterizing the extent of the nonlinearity of the magnetic fields of a beam transport system. Horizontally and vertically oriented pairs of air-core kicker magnets were simultaneously driven at two different frequencies to provide a time-dependent transverse modulation of the beam orbit relative to the unperturbed reference orbit. Fourier decomposition of the position data at eight different points along the beamline was then used to measure the amplitude of these frequencies. For a purely linear transport system one expects to find solely the …

Demand Responsive Signal Control Strategy (Drsc) Incorporating Queue Length Information In Real-Time Signal Control, Rahul Rajbhara

Civil & Environmental Engineering Theses & Dissertations

Most of the existing vehicle detection systems, namely inductive loops, video cameras etc. are incapable of measuring the queue lengths at signalized intersections. However, with the advent of modern technology, newer detection methods such as probe vehicles equipped with wireless communications (Connected Vehicles), particularly under the Vehicle Infrastructure Integration [52), and radar detection currently provide this capability [53). This thesis presents a Demand Responsive Signal Control Strategy (termed as DRSC) for an isolated signalized intersection. The control strategy incorporates real-time queue length information (obtained from probe vehicles) into the signal control logic. Demand based maximum green time for each upcoming/new …

Multidentate Resorcinarene Surfactants For The Phase Transfer Of Metal Nanoparticles And Nanodiamonds: Applications In Catalysis And Diamond Film Growth, Vara Prasad Sheela

Chemistry & Biochemistry Theses & Dissertations

One main objective of the present work is to functionalize cuboctahedral platinum nanoparticles with various multidentate resorcinarene surfactants and study their influence in determining their catalytic activity. We hypothesized that catalytically active and recyclable catalysts can be achieved by incomplete yet strong passivation of the nanoparticle surfaces by using multidentate resorcinarene surfactants. We have developed phase transfer protocols for functionalizing cuboctahedral platinum nanoparticles with resorcinarene thiol or amine. Fluorescence assay confirmed that both these nanoparticles contained almost comparable unpassivated metal area. The activity of such phase transferred nanoparticles was tested in the catalytic hydrogenation of allyl alcohol. The conversion of …

Using Decision-Making Techniques In Support Of Simulation Training Transfer Selections, Jane Taylor Bachman

Computational Modeling & Simulation Engineering Theses & Dissertations

A general methodological approach for determining the selection of military training simulations with respect to military training requirements has not been developed. This thesis undertakes a literature review, which indicated that there was a need for a multi-criteria decision making model to assist acquisition and/or training planners in making training selection decisions. The Analytical Hierarchy Process (AHP) Model was selected from a multi-criteria decision-making model candidate list for evaluation of its efficacy in selecting military training simulations based upon the military training requirements. Four separate trainee populations, Alpha, Beta, Charlie, and Delta, were evaluated. Results from the Alpha study case …

Using Modeling And Simulation To Examine The Benefits Of A Network Tasking Order, Matthew D. Compton, Kenneth M. Hopkinson, Gilbert L. Peterson, James T. Moore

Faculty Publications

The Global Information Grid (GIG) is the military’s computer and communications network which supports the myriad of military missions. Military missions are highly planned, passing through many hands in the strategy-to-task methodology to ensure completeness, accuracy, coordination, cohesion, and appropriateness. A benefit of this planning is the possibility to collect knowledge of future conditions that could be of use to network designers whose goals include optimizing and protecting the GIG. This advanced knowledge includes which networked military equipment will be involved, what their capabilities are, where they will be, when they will be there, and particulars on the required data …

Clearing Paths For Emergency Vehicles Using Shock Wave Theory And Vehicle-To-Vehicle Communication, Craig Austin Jordan

Computational Modeling & Simulation Engineering Theses & Dissertations

A new strategy to enable an EV to navigate through congestion at signalized intersections more efficiently has been developed and is presented in this thesis. The proposed strategy involves communicating control messages to vehicles to change their driving behavior and to traffic signals to change their timing plans so that EV s can proceed through congested intersections as quickly as possible. To achieve this, specific vehicles are instructed to hold their positions to create a split in the vehicle queue at a critical location in one lane. The split allows the EV to change lanes and proceed unimpeded at its …

A Multi-Paradigm Modeling Framework For Modeling And Simulating Problem Situations, Christopher James Lynch

Computational Modeling & Simulation Engineering Theses & Dissertations

Problem situations are problems whose specifications are not universally agreed upon making them a challenge to be modeled and simulated. Models of problem situations depart from the premise of well-defined problems, problems where stakeholders disagree, but also modelers' interpretations play a role in their design and computer implementation.

This thesis proposes a multi-paradigm modeling framework for modeling and simulating problem situations in order to explore the problem space of the problem situations and answer specific modeling questions.

The proposed framework implements the Modeling and Simulation (M&S) System Development Framework (MS-SDF), which is a methodology for modeling a problem situation while …

A Design Of Experiments Approach To Visor Drag Reduction On Heavy Vehicles Using Wind Tunnel Testing, Adam Golembeski

Mechanical & Aerospace Engineering Theses & Dissertations

Drag reduction on a scale wind tunnel model of a tractor and partial trailer was used as a case study to investigate the use of Designed Experiments. Specifically, the drag reduction benefits of replacing a tractor sunvisor with an airfoil shaped sunvisor were investigated. The airfoil-shaped sunvisor was theorized to generate thrust in the direction of travel thus reducing the net drag force. The drag force was measured using a load cell integrated into the tractor-trailer model. The experimental factors were the angle of attack, the horizontal position relative to the surface of the tractor body, the yaw angle and …

A Multi-Objective Differential Evolution Algorithm For Engineering Design Optimization, Shantanu S. Muluk

Mechanical & Aerospace Engineering Theses & Dissertations

The current research investigation focuses on the development of a multi-objective global optimizer based on the differential evolution algorithm. A rotationally invariant version of the original differential evolution algorithm is adopted as the core component of the optimization procedure. The optimizer is applied to a number of multi-objective problems: constrained problems, problems of high dimensionality, and problems with non-convex Pareto fronts.

The effectiveness of the proposed optimization framework in real engineering design problems is demonstrated by carrying out an aerodynamic shape optimization of wind turbine airfoils. The investigation focuses on both thin and thick airfoils. The produced Pareto-optimal airfoil shapes …

Dynamics Of Non-Thermal Plasma Jets Under Variable Pressure, Mehmet Arda Akman

Electrical & Computer Engineering Theses & Dissertations

Non-thermal plasma (NTP) jets driven by short DC pulses have attracted the attention of researchers within the past decade due to their promising bio-medical applications in the fields of wound healing, cancer treatment and sterilization. The ability to operate at atmospheric pressure, room temperature and simple device configuration has greatly contributed to their appeal and adoption in the plasma science community. However, the mechanisms that sustain the plasma generation and propagation in ambient air are currently a topic of debate. For instance, what appears as a continuous stream of a plasma plume extending outwards from a plasma device into the …

Kinematic Analysis Of Gesture In Aphasia, Haroon Osmanzada

Mechanical & Aerospace Engineering Theses & Dissertations

Individuals who have experienced a left hemispheric stroke often develop aphasia, which results in a loss of effective verbal communication and reliance on gesturing to communicate. In this study we combined these two aspects of aphasic word retrieval difficulties and gesturing with three-dimensional kinematics. The purposes of this study were: 1) to develop a preliminary database of upper extremity movements for two common gestures used in gestural facilitation of naming (GES) training, slicing and hammering, in participants who experienced a left-hemisphere stroke and compare them to age-matched healthy controls, and 2) to perform a case study consisting of a single …

Using System Dynamics To Contribute To Ecological Economics, Takuro Uehara, Yoko Nagase, Wayne Wakeland

Complex Systems Faculty Publications and Presentations

This paper demonstrates the usefulness of the system dynamics approach to the development of ecological economics, the study of the interactions between economic systems and ecological systems. We build and analyze an ecological economic model: an extension of a population–resource dynamics model developed by Brander and Taylor and published in American Economic Review in 1998. The focus of the present paper is on the model building and analysis to contribute to theory building rather than eliciting policy implications from the model. Hence, this is an example of model-based theory building using system dynamics. Our analysis sheds light on several problems …

Relating Methanogen Community Structure And Function In Anaerobic Digesters, Benjamin T.W. Bocher

Dissertations (1934 -)

A deeper understanding of how microbial community structure relates to process function would help improve anaerobic digester design. This dissertation describes both qualitative and quantitative relationships between anaerobic digester function and microbial community structure. Community structure was characterized using banding pattern intensities from denaturing gradient gel electrophoresis (DGGE) for the mcrA gene of methanogenic Archaea. The first project compared a single-stage continuously mixed stirred tank reactor (CSTR) and staging with an acidogenic CSTR followed by a methanogenic CSTR. After seeding with the same biomass, these unique process configurations exhibited different function and qualitatively different methanogen communities. Compared to a single-stage …

Constrained Control And Optimization Of Tubular Solid Oxide Fuel Cells For Extending Cell Lifetime, Ben Spivey, John Hedengren, Thomas F. Edgar

Faculty Publications

Extending fuel cell lifetime is a necessary objective for reducing fuel cell power generation cost of electricity. Capital costs comprise the most significant fraction of the cost of electricity. Reducing the frequency of fuel cell replacement can be achieved by implementing a control strategy that prevents excursions into operating regions causing failure. In this paper we implement a constrained MIMO model predictive controller (MPC) to avoid the failure modes relevant for a high-temperature tubular solid oxide fuel cell (SOFC) system while performing load-following. The primary causes of failure are catalyst poisoning, fuel or air starvation, carbon deposition, and microcracking. Prior …

Life Cycle Boundaries And Greenhouse Gas Emissions From Beef Cattle, Quentin M. Dudley

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

Beef cattle are estimated to directly contribute 26% of U.S. agricultural greenhouse gas (GHG) emissions, and future climate change policy may target reducing these emissions. Life cycle assessment (LCA) of GHG emissions from U.S. feedlot beef cattle was conducted to compare methods of the U.S. Environmental Protection Agency (EPA) with a more complete evaluation of emissions. The inclusion of emissions from crop production for feed, associated land use change, and other minor factors nearly doubled GHG emissions associated with beef feedlots from the EPA Annual Inventory estimate of 1611 kgCO₂e hd^-1 yr^-1 to 3182 ± 167 …

Design, Analysis, And Construction Of An Equal Split Wilkinson Power Divider, Logan J. Berens

Master's Theses (2009 -)

The Wilkinson power divider is a well known device in the RF/microwave community used for splitting or combining signals. It is composed of simple transmission lines and a resistor, and takes advantage of the properties of quarter-wavelength transmission line sections to provide ideal power divider characteristics. Three different equal split Wilkinson power dividers are designed to operate near 1800 MHz and constructed using typical microstrip fabrication techniques. The three power dividers each feature a unique design to help determine how the microstrip layout can impact isolation and return loss. A circuit analysis of the general Wilkinson power divider schematic is …

Ergonomic Design Of An Aerial Bucket For Ingress And Egress, Bianca M. Bain

Master's Theses (2009 -)

Electric utility companies across the US have been using aerial bucket trucks for line work and troubleshooting for decades. The use of these trucks eliminates the need for workers to climb utility poles in order to repair or maintain lines. Poor ingress and egress design can lead to acute injuries (slips and falls) as well as cumulative injury (musculoskeletal disorders (MSDs)). Utility companies want to know the best combination of steps and handlebars for aerial bucket ingress and egress that would minimize the risk of injury. American National Standards Institute (ANSI) standard – ANSI/SIA A92.2-2009, sets design requirements for aerial …