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Articles 661 - 690 of 1342

Full-Text Articles in Mechanical Engineering

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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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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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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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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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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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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Mathematical Dynamics Of Fluid Motion Inside Of A Spherical Boundary, Taylor Killian, Dr. Tadd Truscott Jun 2013

Mathematical Dynamics Of Fluid Motion Inside Of A Spherical Boundary, Taylor Killian, Dr. Tadd Truscott

Journal of Undergraduate Research

The purpose of the proposed research was to mathematically define and model the flow of fluid within a partially filled sphere. The goal of this modeling was to aid the study of the effects an enclosed fluid had on its boundary. We desired to demonstrate the movements of the fluid numerically. Professor Truscott’s laboratory observed that the rebound of a sphere, partially filled with fluid, is greatly reduced by the motion of the fluid inside the sphere and wanted to understand the dynamics of this event.

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Capillary Action In A Rectangular Micro-Channel, Jeffrey Hendricks, Dr. Tadd Truscott Jun 2013

Capillary Action In A Rectangular Micro-Channel, Jeffrey Hendricks, Dr. Tadd Truscott

Journal of Undergraduate Research

The study of fluid flow on a microscale has become of increasing interest in recent years. We have studied the effects of capillary action in a micro-channel with a rectangular cross-section having a large width to height ratio. In general, capillary action allows fluid to fill a horizontally oriented tube smaller than the capillary length (on the order of 2 mm in water). When the far end of such a tube is capped, typically the fluid is drawn through the tube until it meets a pressure field that is equal but opposite of the surface tension force. We have found …

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Rebound Suppression Of A Partially Filled Sphere, Robert Klaus, Dr. Tadd Truscott Jun 2013

Rebound Suppression Of A Partially Filled Sphere, Robert Klaus, Dr. Tadd Truscott

Journal of Undergraduate Research

Sloshing is a very common phenomenon that we encounter everyday. Anytime that a liquid is enclosed within a moving container there exists the potential for sloshing. In some cases, such as trucks & ships, the sloshing of the fluid can produce undesired vehicle motion and even lead to catastrophic results. On the other hand, street hockey balls use fluid sloshing to help mitigate the rebound inherent to elastic spheres. In this research, high-speed imaging has been used to capture the sloshing motion and understand its effect on the rebound of partially filled, hollow, elastic spheres.

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Spinning Objects In A Shallow Bath: Eggs In Milk, Kenneth Langley, Dr. Tadd Truscott Jun 2013

Spinning Objects In A Shallow Bath: Eggs In Milk, Kenneth Langley, Dr. Tadd Truscott

Journal of Undergraduate Research

If an egg spinning on a counter-top passes through a shallow pool of milk, a thin film of milk will be drawn up the sides of the egg and sprayed on the counter-top. This phenomenon is not limited to eggs or milk. In fact, when any axis-symmetric object is spun in a shallow bath of fluid, this phenomenon occurs in which fluid flows up the object and is then ejected at the maximum radius. This phenomenon lends itself well as a pump for moving fluids from very shallow areas to other regions and can even be used to make droplets …

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Combustion-Driven Water Heating In Huatta, Peru: A Solution For Third-World Countries, Brandon Decker, Dr. Matt Jones Jun 2013

Combustion-Driven Water Heating In Huatta, Peru: A Solution For Third-World Countries, Brandon Decker, Dr. Matt Jones

Journal of Undergraduate Research

This group aimed to construct a system that heated water to at least 38°C (100 OF) – warm enough for bathing, dish washing, and washing hands. Our goal was to create a system inexpensive and simple enough for implementation in Huatta, Peru. We also aimed to make the system sustainable and replicable.

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Forked Shaped Rebound Droplet For Impingement On Anisotropic Superhydrophobic Surfaces, David Bilodeau, Dr. Daniel Maynes Jun 2013

Forked Shaped Rebound Droplet For Impingement On Anisotropic Superhydrophobic Surfaces, David Bilodeau, Dr. Daniel Maynes

Journal of Undergraduate Research

Many metals rust when exposed to moisture and that rusting can cause the item that is made of that metal to break down. A superhydrophobic surface can repel liquids and keep metals from rusting longer. Superhydrophobic surfaces have existed in nature for a long time but are just beginning to be understood and manufactured for societal applications. They are manufactured by micro-texturing a surface that is either made from specific materials or is coated with a different material after the micro-texturing (see Figure 1). Both the material and the micro-geometry are important parameters in the surface‟s ability to repel liquids. …

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An Improved Estimation Of Passive Wrist Stiffness Using Various Techniques, Will Drake, Dr. Steven Charles Jun 2013

An Improved Estimation Of Passive Wrist Stiffness Using Various Techniques, Will Drake, Dr. Steven Charles

Journal of Undergraduate Research

The wrist plays a vital yet frequently overlooked role in positioning and supporting the hand during activities of daily living. Particularly during low-level activities (such as typing), passive joint stiffness dominates wrist dynamics and constitutes the main obstacle to motion. In spite of its importance, however, little consensus exists as to the exact range of passive wrist stiffness. Reported values vary from as little as 0.002 Nm/rad (Lehman & Calhoun, 1991) to as many as 9.0 Nm/rad (Crisco et al, 2010), a span of three orders of magnitude! The purpose of this research is to determine an approximate single-order-of-magnitude range …

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Stand-Alone Lance For Nanoinjection Of Dna, Mark Fernelius, Dr. Larry Howell Jun 2013

Stand-Alone Lance For Nanoinjection Of Dna, Mark Fernelius, Dr. Larry Howell

Journal of Undergraduate Research

Technologies for injecting DNA into egg cells have greatly facilitated genetic research. Microinjection is a current standard for this purpose. It uses a hollow glass needle to inject a solution containing DNA into cells. Although widely used, microinjection has several significant challenges. First, the DNA can be damaged when forced through the small opening of the needle. Second, the cell can die from the physical trauma caused by the microinjection needle piercing the cell membrane. Third, the cell can split open because of the increased internal pressure caused by injecting fluid into the cell. Brigham Young University has developed nanoinjection …

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An Alternative System Identification Method For Friction Stir Processing, Dustin John Marshall Jun 2013

An Alternative System Identification Method For Friction Stir Processing, Dustin John Marshall

Theses and Dissertations

Temperature control has been implemented in friction stir processing and has demonstrated the ability to give improved process control. In order to have optimal control of the process, the parameters of the system to be controlled must be accurately identified. The system parameters change with tool geometry and materials, workpiece materials, and temperature. This thesis presents the use of the relay feedback test to determine the system parameters. The relay feedback test is easy to use and promotes system stability during its use. The results from the relay feedback test can be used to determine controller gains for a PID …

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Fluid-Structure Interactions With Flexible And Rigid Bodies, David J. Daily May 2013

Fluid-Structure Interactions With Flexible And Rigid Bodies, David J. Daily

Theses and Dissertations

Fluid structure interactions occur to some extent in nearly every type of fluid flow. Understanding how structures interact with fluids and visa-versa is of vital importance in many engineering applications. The purpose of this research is to explore how fluids interact with flexible and rigid structures. A computational model was used to model the fluid structure interactions of vibrating synthetic vocal folds. The model simulated the coupling of the fluid and solid domains using a fluid-structure interface boundary condition. The fluid domain used a slightly compressible flow solver to allow for the possibility of acoustic coupling with the subglottal geometry …

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A Multiobjective Optimization Method For Collaborative Products With Application To Engineering-Based Poverty Alleviation, Nicholas Scott Wasley May 2013

A Multiobjective Optimization Method For Collaborative Products With Application To Engineering-Based Poverty Alleviation, Nicholas Scott Wasley

Theses and Dissertations

Collaborative products are created by combining components from two or more products to result in a new product that performs previously unattainable tasks. The resulting reduction in cost, weight, and size of a set of products needed to perform a set of functions makes collaborative products useful in the developing world. In this thesis, multiobjective optimization is used to design a set of products for optimal individual and collaborative performance. This is introduced through a nine step method which simultaneously optimizes multiple products both individually and collaboratively. The method searches through multiple complex design spaces while dealing with various trade-offs …

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A Mathematical Model For Quantifying System Evolvability Using Excess And Modularity, Morgan Wesley Parry Tackett May 2013

A Mathematical Model For Quantifying System Evolvability Using Excess And Modularity, Morgan Wesley Parry Tackett

Theses and Dissertations

An important factor in system longevity is service-phase evolvability, which is defined as the ability of a system to physically transform from one configuration to a more desirable configuration while in service. These transformations may or may not be known during the design process, and may or may not be reversible. A study of 210 engineered systems was performed and found that system excess and modularity allow a system to evolve while in service. Building on these observations, this thesis introduces mathematical relationships that map a system's excess and modularity to that system's ability to evolve. These relationships are derived …

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Using Topology Optimization To Numerically Improve Barriers To Reverse Engineering, Devin Donald Lebaron May 2013

Using Topology Optimization To Numerically Improve Barriers To Reverse Engineering, Devin Donald Lebaron

Theses and Dissertations

Here explored is a method by which designers can use the tool of topology optimization to numerically improve barriers to reverse engineering. Recently developed metrics, which characterize the time (T) to reverse engineer a product, enable this optimization. A key parameter use din the calculation of T is information content (K). The method presented in this thesis pursues traditional topology optimization objectives while simultaneously maximizing K, and thus T, in the resulting topology. This thesis presents new algorithms to 1) evaluate K for any topology, 2)increase K for a topology by manipulating macro-scale geometry and micro-scale crystallographic information for each …

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Floating Electrode Electrowetting On Hydrophobic Dielectric With An Sio2 Layer, Mehdi Khodayari, Benjamin Hahne, Nathan B. Crane, Alex A. Volinsky May 2013

Floating Electrode Electrowetting On Hydrophobic Dielectric With An Sio2 Layer, Mehdi Khodayari, Benjamin Hahne, Nathan B. Crane, Alex A. Volinsky

Faculty Publications

Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the Cytop surface, without electrical connection to the substrate. The effect is caused by the charge separation in the floating electrode. A highly-resistive thermally-grown SiO2 layer underneath the Cytop enables the droplet to hold charges without leakage, which is the key contribution. Electrowetting with an SiO2 layer shows a memory effect, where the wetting angle stays the same after the auxiliary electrode is removed from the droplet in both conventional and floating electrode electrowetting. Floating electrode electrowetting provides an alternative configuration for developing advanced electrowetting-based devices.

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An Exploration Of Carbon-Filled Carbon Nanotubes As A Potential Material In Coronary Stents, Kristopher Neil Jones May 2013

An Exploration Of Carbon-Filled Carbon Nanotubes As A Potential Material In Coronary Stents, Kristopher Neil Jones

Theses and Dissertations

The purpose of this research is to explore the potential of using carbon-infiltrated carbon nanotubes (CI-CNT) as a material for coronary artery stents. Stents are commonly fabricated from metal, which may not perform as well as many polymers and ceramics in biomedical applications. Pyrolytic carbon, a ceramic, is currently used in medical implant devices due to its preferrable biocompatibility properties. Micro-patterned pyrolytic carbon devices can be created by growing carbon nanotubes, and then filling the space between with amorphous carbon via chemical vapor deposition. We prepared multiple samples of two different planar stent-like flexible geometries and smaller cubic structures out …

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Relative Navigation Approach For Vision-Based Aerial Gps-Denied Navigation, Robert C. Leishman, Timothy Mclain, Randal W. Beard May 2013

Relative Navigation Approach For Vision-Based Aerial Gps-Denied Navigation, Robert C. Leishman, Timothy Mclain, Randal W. Beard

Faculty Publications

GPS-denied aerial flight is a popular research topic. The problem is challenging and requires knowledge of complex elements from many distinct disciplines. Additionally, aerial vehicles can present challenging constraints such as stringent payload limitations and fast vehicle dynamics. In this paper we propose a new architecture to simplify some of the challenges that constrain GPS-denied aerial flight. At the core, the approach combines visual graph-SLAM with a multiplicative extended Kalman filter. More importantly, for the front end we depart from the common practice of estimating global states and instead keep the position and yaw states of the MEKF relative to …

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Analysis Of An Improved Imu-Based Observer For Multirotor Helicopters, John Charles Macdonald, Robert C. Leishman, Randal W. Beard, Timothy W. Mclain May 2013

Analysis Of An Improved Imu-Based Observer For Multirotor Helicopters, John Charles Macdonald, Robert C. Leishman, Randal W. Beard, Timothy W. Mclain

Faculty Publications

Multirotor helicopters are increasingly popular platforms in the robotics community. Making them fully autonomous requires accurate state estimation. We review an improved dynamic model for multirotor helicopters and analyze the observability properties of an estimator based on this model. The model allows better use of IMU data to facilitate accurate state estimates even when updates from a sensor measuring position become less frequent and less accurate. We demonstrate that the position update rate can be cut in half versus typical approaches while maintaining the same accuracy. We also find that velocity estimates are at least twice as accurate no matter …

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A Vision-Based Relative Navigation Approach For Autonomous Multirotor Aircraft, Robert C. Leishman Apr 2013

A Vision-Based Relative Navigation Approach For Autonomous Multirotor Aircraft, Robert C. Leishman

Theses and Dissertations

Autonomous flight in unstructured, confined, and unknown GPS-denied environments is a challenging problem. Solutions could be tremendously beneficial for scenarios that require information about areas that are difficult to access and that present a great amount of risk. The goal of this research is to develop a new framework that enables improved solutions to this problem and to validate the approach with experiments using a hardware prototype. In Chapter 2 we examine the consequences and practical aspects of using an improved dynamic model for multirotor state estimation, using only IMU measurements. The improved model correctly explains the measurements available from …

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Mimicking The Mechanical Behavior Of Advancing Disc Degeneration Through Needle Injections, Jeremy S. Alsup Apr 2013

Mimicking The Mechanical Behavior Of Advancing Disc Degeneration Through Needle Injections, Jeremy S. Alsup

Theses and Dissertations

Objective - To investigate the effects of injected protease solution on the mechanical advancement of disc degeneration, and to establish test protocol for future pre-clinical validation of spinal arthroplasty devices. The hypothesis that injection of a protease into a cadaveric lumbar disc will mimic advanced degeneration mechanics was the subject of this study. Summary of Background Information - Spinal disc degeneration is a universal condition that progresses in adults due to aging, disease, or injury. Stages of disc degeneration have been categorized in cadaver specimens, with each degeneration level exhibiting characteristic changes in flexibility parameters. Spinal disc tissue can be …

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