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Articles 3091 - 3120 of 4850

Full-Text Articles in Engineering

The Effect Of Cooling Rate Of Friction Stir Welded High Strength Low Alloy Steel, Scott Anthony Rose Jul 2013

The Effect Of Cooling Rate Of Friction Stir Welded High Strength Low Alloy Steel, Scott Anthony Rose

Theses and Dissertations

The friction stir welding of steel has produced a hard zone in several different alloys. Despite its detrimental effects on weld toughness, the reasons behind neither its formation nor a method of reducing its size or effects have been explored. Recent advances in process control allow for direct heat input control, which combined with the use of backing plates of different thermal conductivity allows for an expansion of the process window. These control methods also affect the HAZ cooling rate by providing greater range (a 60% increase compared to a fixed backing plate) and control (five welds within 16 °C/s). …

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Popup Height And The Dynamics Of Rising Buoyant Spheres, Randy H. Munns Jul 2013

Popup Height And The Dynamics Of Rising Buoyant Spheres, Randy H. Munns

Theses and Dissertations

In this paper the popup height of rising buoyant spheres is studied over a range of distinct release depths along with the accompanying velocities and accelerations near the free surface. In the past, regimes of motion due to vortex induced vibrations have been classified based on trajectories below the free surface. This study focuses on the popup height, velocity and acceleration at free surface exit, and vortex shedding in order to further define regimes of motion experienced by a rising buoyant sphere. Varying the release depth below the free surface reveals varying exit angles, velocities, accelerations, and popup heights at …

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A Comparative Analysis Of Energy Modelingmethods For Commercial Buildings, Spencer Mark Salmon Jul 2013

A Comparative Analysis Of Energy Modelingmethods For Commercial Buildings, Spencer Mark Salmon

Theses and Dissertations

This thesis researched the accuracy of measured energy data in comparison to estimated hand calculation data and estimated building energy performance simulation data. In the facility management industry, there is minimal evidence that building energy performance software is being used as a benchmark against measured energy usage within a building. Research was conducted to find examples of measured energy data compared to simulated data. The study examined the accuracy of a simulation software and hand calculations to measured energy data. Data suggests that comparisons may be made between building energy performance simulated data and measured data, though comparisons are solely …

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Improvements In Diffusion Weighted Imaging Through A Composite Body And Insert Gradient Coil System, Peter Austin Jepsen Jul 2013

Improvements In Diffusion Weighted Imaging Through A Composite Body And Insert Gradient Coil System, Peter Austin Jepsen

Theses and Dissertations

Diffusion Magnetic Resonance Imaging (DMRI) is a class of Magnetic Resonance Imaging (MRI) techniques with broad medical applications ranging from characterization of tumors and brain damage to potential prediction of stroke. Gradient coil and signal-to- noise ratio (SNR) constraints limit spatial resolution, accuracy, and scan time in DMRI. Achieving high b-values (measures of a scan's sensitivity to diffusion) often require scans with long diffusion gradient pulses, leading to significant magnetic resonance (MR) signal decay before the signal can be sampled. This signal loss reduces the accuracy of diffusion parameter estimation. The ability to sample the MR signal sooner while maintaining …

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Gesture Analysis For Human-Computer Interface Using Profile-Matching Stereo Vision, Yung Ping Chang Jul 2013

Gesture Analysis For Human-Computer Interface Using Profile-Matching Stereo Vision, Yung Ping Chang

Theses and Dissertations

This thesis presents a novel profile shape matching stereo vision algorithm. This algorithm is able to obtain 3D information in real time from a pair of stereo images. This algorithm produces the 3D information by matching the profile intensity shapes on the same row of the two images from a stereo image pair. The advantage of this profile shape matching algorithm is that the detection of correspondences relies on intensity profile shape not on intensity values, which subject to lighting variations. The user can choose an interval of disparity, and then an object in a desired distance range can be …

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Variable Fidelity Optimization With Hardware-In-The-Loop For Flapping Flight, Michael Luke Duffield Jul 2013

Variable Fidelity Optimization With Hardware-In-The-Loop For Flapping Flight, Michael Luke Duffield

Theses and Dissertations

Hardware-in-the-loop (HIL) modeling is a powerful way of modeling complicated systems. However, some hardware is expensive to use in terms of time or mechanical wear. In cases like these, optimizing using the hardware can be prohibitively expensive because of the number of calls to the hardware that are needed. Variable fidelity optimization can help overcome these problems. Variable fidelity optimization uses less expensive surrogates to optimize an expensive system while calling it fewer times. The surrogates are usually created from performing a design of experiments on the expensive model and fitting a surface to the results. However, some systems are …

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Modeling And Optimization Of Space Use And Transportation For A 3d Walkable City, Bradley R. Mecham Jul 2013

Modeling And Optimization Of Space Use And Transportation For A 3d Walkable City, Bradley R. Mecham

Theses and Dissertations

This thesis presents an investigation of a new three-dimensional urban form where walking distances are less than a half-mile and congestion is minimal. The car-free urban form investigated herein is a city composed of skyscrapers massively interconnected with skybridges at multiple levels. The investigation consists of optimizing space use arrangement, skybridge presence or absence, and elevator number to simultaneously minimize total travel time, skybridge light blockage, and elevator energy usage in the city. These objectives are evaluated using three objective functions, the most significant of which involves a three-dimensional, pedestrian-only, three-step version of the traditional four-step planning model. Optimal and …

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The Sustainability Of Lean Manufacturing As A Competitive Advantage, Louis G. Jones Jul 2013

The Sustainability Of Lean Manufacturing As A Competitive Advantage, Louis G. Jones

Theses and Dissertations

Since the early 1990s lean manufacturing has been employed by companies looking to reduce costs, increase efficiencies and improve quality. Academic studies of the financial benefits of lean manufacturing are mixed in their results, where some show benefit and others do not. The objective of the current work was to confirm a financial benefit of lean manufacturing, while also establishing whether such a financial advantage was sustainable. Financial data was collected for a large number of companies in the manufacturing sector, over the period from 1990 to 2010. The data were used to show correlation between inventory turns and return …

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Large-Scale Testing Of Passive Force Behavior For Skewed Abutments With High Width-Height Ratios, Katie Noel Palmer Jul 2013

Large-Scale Testing Of Passive Force Behavior For Skewed Abutments With High Width-Height Ratios, Katie Noel Palmer

Theses and Dissertations

The effects of seismic forces and thermal expansion on bridge performance necessitate an accurate understanding of the relationship between passive force and backwall deflection. In past case studies, skewed bridges exhibited significantly more damage than non-skewed bridges. These findings prompted studies involving numerical modeling, lab-scale tests, and large-scale tests that each showed a dramatic reduction in passive force with increased skew. Using these results, a correlation was developed between peak passive force and backwall skew angle. The majority of these tests had length to height ratios of 2.0; however, for several abutments in the field, the length to height ratio …

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An Analysis Of The Provo River Decree And Its Current Application To Provo Area Water Rights, Karsten Eugene Busby Jul 2013

An Analysis Of The Provo River Decree And Its Current Application To Provo Area Water Rights, Karsten Eugene Busby

Theses and Dissertations

Water scarcity in the west has created a long history of conflict. When Utah was settled, laws were instituted (both officially and otherwise) that allowed water users to use streams and springs in efficient ways without causing harm to other users. The Provo River Decree is a physical example of local water law that has been in place for almost a hundred years. While many changes have arisen in its area of jurisdiction, it is still drawn upon to determine water rights. Ambiguity, rigidity, and overall changes to use patterns have limited the application of the decree to present situations. …

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The Water Entry Of Slender Axisymmetric Bodies: Forces, Trajectories And Acoustics, Kyle Gordon Bodily Jul 2013

The Water Entry Of Slender Axisymmetric Bodies: Forces, Trajectories And Acoustics, Kyle Gordon Bodily

Theses and Dissertations

Free surface water entry of various objects has been studied using high-speed images and image processing techniques for decades. This thesis studies the forces, velocities, and trajectories of slender axisymmetric projectiles using an embedded inertial measurement unit (IMU). Three nose shapes (cone, ogive, and flat) were used in the study. Additionally, the projectiles were tested at vertical and oblique impact angles with different surface conditions. One-half of each projectile was coated down the centerline with a hydrophobic spray, creating a half hydrophobic, half hydrophilic case. The trajectory of this half-and-half case impacting vertically was compared to the trajectory of symmetrically …

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Cryogenic Carbon Capture Using A Desublimating Spray Tower, Bradley J. Nielson Jul 2013

Cryogenic Carbon Capture Using A Desublimating Spray Tower, Bradley J. Nielson

Theses and Dissertations

Global warming is becoming ever increasing concern in our society. As such the likelihood of a carbon tax in the US is becoming increasingly likely. A carbon tax will be expensive enough that coal-based power plants will either have to install carbon capture technology or close. The two front runner technologies for carbon capture are amine scrubbing, and oxyfuel combustion. The downside is that both of these technologies increase power generation cost in a new plant by about 80% and have up to a 30% parasitic load, which reduces the cycle efficiency, that is, the power production per unit fuel …

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Aqueous Henry's Law Constants, Infinite Dilution Activity Coefficients, And Water Solubility: Critically Evaluated Database, Experimental Analysis, And Prediction Methods, Sarah Ann Brockbank Jul 2013

Aqueous Henry's Law Constants, Infinite Dilution Activity Coefficients, And Water Solubility: Critically Evaluated Database, Experimental Analysis, And Prediction Methods, Sarah Ann Brockbank

Theses and Dissertations

A database containing Henry's law constants, infinite dilution activity coefficients and solubility data of industrially important chemicals in aqueous systems has been compiled. These properties are important in predicting the fate and transport of chemicals in the environment. The structure of this database is compatible with the existing DIPPR® 801 database and DIADEM interface, and the compounds included are a subset of the compounds found in the DIPPR® 801 database. Thermodynamic relationships, chemical family trends, and predicted values were carefully considered when designating recommended values. Henry's law constants and infinite dilution activity coefficients were measured for toluene, 1-butanol, anisole, 1,2-difluorobenzene, …

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The Effect Of Carbon Additives On The Microstructure And Performance Of Alkaline Battery Cathodes, Douglas Robert Nevers Jul 2013

The Effect Of Carbon Additives On The Microstructure And Performance Of Alkaline Battery Cathodes, Douglas Robert Nevers

Theses and Dissertations

This thesis describes research to understand the relationships between materials, microstructure, transport processes, and battery performance for primary alkaline battery cathodes. Specifically, the effect of various carbon additives, with different physical properties, on electronic transport or conductivity within battery cathodes was investigated. Generally, the electronic conductivity increases with carbon additives that have higher aspect ratios, smaller particle diameters, higher surface areas, and lower bulk densities. Other favorable carbon aspects include more aggregated and elongated carbon domains which permit good particleto-particle contacts. Of the various carbon additives investigated, graphene nanopowder was the best performer. This graphene nanopowder had the smallest particle …

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Dynamics And Control Of Wrist And Forearm Movements, Allan W. Peaden Jul 2013

Dynamics And Control Of Wrist And Forearm Movements, Allan W. Peaden

Theses and Dissertations

Wrist and forearm motion is governed both by its dynamics and the control strategies employed by the neuromuscular system to execute goal oriented movement. Two experiments were conducted to increase our understanding of wrist and forearm motion. The first experiment involved 10 healthy subjects executing planned movements to targets involving all three degrees of freedom (DOF) of the wrist and forearm, namely wrist flexion-extension (FE), wrist radial-ulnar deviation, and forearm pronation-supination (PS). A model of wrist and forearm dynamics was developed, and the recorded movements were fed into the model to analyze the movement torques. This resulted in the following …

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A Study Of Action Origami As Systems Of Spherical Mechanisms, Landen A. Bowen Jul 2013

A Study Of Action Origami As Systems Of Spherical Mechanisms, Landen A. Bowen

Theses and Dissertations

Origami, the Japanese art of paper folding, has been used previously to inspire engineering solutions for compact, deployable designs. Action origami, the subset of origami dealing with models designed to move, is a previously unexplored area for engineering design solutions that are deployable and have additional motion in the deployed state. A literature review of origami in engineering is performed, resulting in seven key areas of technical origami literature from a wide variety of disciplines. Spherical mechanisms are identified as the method by which most action origami models achieve complicated motion while remaining flat-foldable. The subset of action origami whose …

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Capillary Filling Of Large Aspect Ratio Channels With Varying Wall Spacing, Dallin B. Murray Jul 2013

Capillary Filling Of Large Aspect Ratio Channels With Varying Wall Spacing, Dallin B. Murray

Theses and Dissertations

Quantification and prediction of capillary fluid flow in planar nanochannels is essential to the development of many emerging nanofluidic technologies. Planar nanochannels are typically produced using the standard nanofabrication processes of thermal bonding or sacrificial etching. Both approaches may yield nanochannels that are bowed and/or exhibit non-uniform (i.e. non-planar) wall spacing. These variations in wall spacing affect the transient dynamics of a liquid plug filling the nanochannel, causing deviations from the classical behavior in a parallel-plate channel as described by the Washburn model. Non uniform wall spacing impacts the overall frictional resistance and influences the meniscus curvature. In this thesis, …

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Numerical Simulation Of Convection In Triangular Cavities To Predict Solar Still Performance, Jeremy D. Lefevre, W. Jerry Bowman, Matthew R. Jones Jul 2013

Numerical Simulation Of Convection In Triangular Cavities To Predict Solar Still Performance, Jeremy D. Lefevre, W. Jerry Bowman, Matthew R. Jones

Faculty Publications

To improve modeling of solar still behavior, the convection correlations currently used need to be improved upon. Variations in operating parameters and cover geometries make it difficult to use a single correlation to describe the operation of all solar stills. In this work, three right triangles (representing covers at 15, 30, and 45 deg) were modeled, meshed, and solved to predict the convection heat transfer inside for a variety of operating conditions. For a correlation of the form Nu = C · Ran, it was found that C = 1.1, 0.60, and 0.71, and n = 0.19, 0.24, …

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Dynamic Optimization Of A Solar Thermal Energy Storage System Over A 24 Hour Period Using Weather Forecasts, Kody Powell, John Hedengren, Thomas F. Edgar Jul 2013

Dynamic Optimization Of A Solar Thermal Energy Storage System Over A 24 Hour Period Using Weather Forecasts, Kody Powell, John Hedengren, Thomas F. Edgar

Faculty Publications

A solar thermal power plant is used as a case study for dynamic heat integration with thermal energy storage. Findings show that thermal energy storage gives the system the ability to make the power dispatchable. Additionally, by solving a 24-hour dynamic optimization problem where the plant temperatures and power output are variable allows the system to capture and harvest a higher percentage of solar energy, with the most benefit occurring on mostly cloudy days. The solar energy captured increases 64% from 4.75 MWh to 7.80 MWh using this scheme. Hybrid plant operation and the ability to bypass the storage tanks …

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Inviscid Analysis Of Extended Formation Flight, James Kless, Michael Aftosmis, Andrew Ning, Marian Nemec Jul 2013

Inviscid Analysis Of Extended Formation Flight, James Kless, Michael Aftosmis, Andrew Ning, Marian Nemec

Faculty Publications

Flying airplanes in extended formations, with separation distances of tens of wingspans, significantly improves safety while maintaining most of the fuel savings achieved in close formations. The present study investigates the impact of roll trim and compressibility at a fixed lift coefficient on the benefits of extended formation flight. An Euler solver with adjoint-based mesh refinement combined with a wake propagation model is used to analyze a two-body echelon formation at a separation distance of 30 spans. Two geometries are examined: a simple wing and a wing-body geometry. Energy savings, quantified by both formation drag fraction and span efficiency factor, …

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Model Predictive Control With A Rigorous Model Of A Solid Oxide Fuel Cell, Lee T. Jacobsen, John Hedengren Jul 2013

Model Predictive Control With A Rigorous Model Of A Solid Oxide Fuel Cell, Lee T. Jacobsen, John Hedengren

Faculty Publications

Degradation of Solid Oxide Fuel Cells (SOFCs) can be minimized by maintaining reliability parameters during load changes. These reliability parameters are critical to maintain power generation efficiency over an extended life of the SOFC. For SOFCs to be commercially viable, the life must exceed 20,000 hours for load following applications. This is not yet achieved because transient stresses damage the fuel cell and degrade the performance over time. This study relates the development of a dynamic model for SOFC systems in order to predict optimal manipulated variable moves along a prediction horizon. The model consists of hundreds of states and …

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Boiling Heat Transfer On Superhydrophobic Surfaces, Nathan Tulett, Dr. Daniel Maynes Jun 2013

Boiling Heat Transfer On Superhydrophobic Surfaces, Nathan Tulett, Dr. Daniel Maynes

Journal of Undergraduate Research

In the last few years a great deal of attention has been given to superhydrophobic surfaces and their impact on drag reduction in fluid flow dynamics. Such surfaces are now employed as self-cleaning substrates and it is expected that their use in the coming years will greatly multiply. In the laboratory, these surfaces often consist of alternating microribs and microcavities that are etched into a silicone substrate using a deep reactive ion etching process (DRIE) as seen in Fig. 1.

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Optimizing Redundant Wrist And Forearm Rotations, Jenny Pate, Dr. Steven Charles Jun 2013

Optimizing Redundant Wrist And Forearm Rotations, Jenny Pate, Dr. Steven Charles

Journal of Undergraduate Research

Many Americans struggle with wrist injuries that severely impact their ability to work (typing, writing, etc.) and perform basic everyday functions (eating, holding, etc). These injuries often result from repeatedly forcing the wrist to move in unnatural ways. To properly combat these challenges and improve the lives of wrist patients, a better understanding of the human wrist is required. Extensive research has been conducted in arm reaching movements, but limited documentation has been presented regarding the human wrist. In particular, although it appears that humans choose certain wrist movements over others, it is unclear which paths are preferred, why they …

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Developing The Confocal And Fluorescence Microscopy Techniques To Visualize The Eliposomes Inside Of Cells To Treat Cancer, Tara Pandey, Dr. William Pitt Jun 2013

Developing The Confocal And Fluorescence Microscopy Techniques To Visualize The Eliposomes Inside Of Cells To Treat Cancer, Tara Pandey, Dr. William Pitt

Journal of Undergraduate Research

Cancer is among the leading causes of death in the world. The goal for this project was to visualize a liposome containing perfluorocarbon emulsion an eLiposome, inside of tumor cells using confocal and fluorescence microscopes. A successful study of this project would help to understand the behavior of cancer cells in the presence of drugs during targeted drug delivery for cancer.

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Corrosion Measurement Of Reinforcing Steel In Concrete Using Electrochemical Impedance Spectroscopy, Eric Sumsion, Dr. Spencer Guthrie Jun 2013

Corrosion Measurement Of Reinforcing Steel In Concrete Using Electrochemical Impedance Spectroscopy, Eric Sumsion, Dr. Spencer Guthrie

Journal of Undergraduate Research

Corrosion affects reinforced concrete structures throughout the world. Corrosion, induced by concrete carbonation and penetration of chloride ions from deicing salts and/or seawater, reduces the load-bearing area of reinforcing steel, weakens the bond between steel and concrete, and cracks the concrete surrounding the steel. As a result of these effects, corrosion can cause premature failure of reinforced concrete structures.

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Using Ebsd Images To Determine 3d Crystal Structure, Caroline Sorensen, Dr. David Fullwood Jun 2013

Using Ebsd Images To Determine 3d Crystal Structure, Caroline Sorensen, Dr. David Fullwood

Journal of Undergraduate Research

The research I have completed over the past year has been very successful. The results will soon (i.e. in the next week or two) be submitted for publication, most likely to the journal “Metallurgical and Material Transactions A.” Preliminary findings from this research were also presented earlier this year at the annual conference of The Minerals, Metals, & Materials Society in San Diego, CA. In this final report I will overview the initial goal and proposed methods, outline a few of the problems that were encountered and solved in my research, discuss the implications of the results, and suggest further …

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High Resolution Characterization Of Polycrystalline Triple Junctions, Samikshya Subedi, Dr. David Fullwood Jun 2013

High Resolution Characterization Of Polycrystalline Triple Junctions, Samikshya Subedi, Dr. David Fullwood

Journal of Undergraduate Research

The purpose of this study was to understand and predict the role of the triple junction on crack initiation in polycrystals. I intended to study dislocation density fields and local elastic strain around the triple junction area in a metal and understand how these factors facilitate crack nucleation and propagation.

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Flapping Flight, Michael Tree, Dr. Scott Thomson Jun 2013

Flapping Flight, Michael Tree, Dr. Scott Thomson

Journal of Undergraduate Research

Operation of existing micro air vehicles (small, unmanned aircraft, with a maximum size of 6 inches or less, also known as MAVs) is difficult in urban areas. Most MAVs use a fixed-wing design that is unsuitable for high maneuverability, thus limiting their potential usefulness.

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The Effect Of Lanthanum On Iron Based Water-Shift Catalysts, Trevor Slade, Dr. Morris Argyle Jun 2013

The Effect Of Lanthanum On Iron Based Water-Shift Catalysts, Trevor Slade, Dr. Morris Argyle

Journal of Undergraduate Research

The water-gas shift reaction is the reaction where carbon monoxide and water react to form carbon dioxide and hydrogen as shown in equation 1.

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Research And Testing Of Pvc Solvent Bonding Methods, David Williams, Dr. William Pitt Jun 2013

Research And Testing Of Pvc Solvent Bonding Methods, David Williams, Dr. William Pitt

Journal of Undergraduate Research

The purpose of this research project was to determine the optimal method to solvent bond polyvinyl chloride (PVC) pieces together. Understanding how to create a strong solvent bond in PVC is important to a related prosthetic leg project that has been performed at BYU. This was completed by bonding flat samples of PVC that were prepared with varying methods.

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