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Articles 3151 - 3180 of 4850

Full-Text Articles in Engineering

Arrow-Based On-Chip Alkali Vapor-Cell Development, John Frederick Hulbert May 2013

Arrow-Based On-Chip Alkali Vapor-Cell Development, John Frederick Hulbert

Theses and Dissertations

The author presents the successful development of an on-chip, monolithic, integrated rubidium vapor-cell. These vapor-cells integrate ridge waveguide techniques with hollow-core waveguiding technology known as Anti-Resonant Reflecting Optical Waveguides (ARROWs). These devices are manufactured on-site in BYU's Integrated Microelectronic Laboratory (IML) using common silicon wafer microfabrication techniques. The ARROW platform fabrication is outlined, but the bulk of the dissertation focuses on novel packaging techniques that allow for the successful introduction and sealing of rubidium vapor into these micro-sized vapor-cells. The unique geometries and materials utilized in the ARROW platform render common vapor-cell sealing techniques unusable. The development of three generations …

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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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Extension Of Dna In A Nanochannel As A Rod-To-Coil Transition, Douglas R. Tree, Yanwei Wang, Kevin D. Dorfman May 2013

Extension Of Dna In A Nanochannel As A Rod-To-Coil Transition, Douglas R. Tree, Yanwei Wang, Kevin D. Dorfman

Faculty Publications

DNA confinement in nanochannels is emerging as an important tool for genomics and an excellent platform for testing the theories of confined wormlike polymers. Using cutting-edge, large scale Monte Carlo simulations of asymptotically long wormlike chains, we show that, in analogy to the rod-to-coil transition for free wormlike polymers, there exists a universal, Gauss–de Gennes regime that connects the classic Odijk and de Gennes regimes of channel-confined chains. For DNA in a nanochannel, this Gauss–de Gennes regime spans practically the entire experimentally relevant range of channel sizes, including the nanochannels used in an incipient genome mapping technology.

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Techniques For Li-Bdn Synthesis For Hybrid Microarchitectural Simulation, Tyler S. Harris May 2013

Techniques For Li-Bdn Synthesis For Hybrid Microarchitectural Simulation, Tyler S. Harris

Theses and Dissertations

Computer designers rely upon near-cycle-accurate microarchitectural simulation to explore the design space of new systems. Unfortunately, such simulators are becoming increasingly slow as systems become more complex. Hybrid simulators which offload some of the simulation work onto FPGAs can increase the speed; however, such simulators must be automatically synthesized or the time to design them becomes prohibitive. Furthermore, FPGA implementations of simulators may require multiple FPGA clock cycles to implement behavior that takes place within one simulated clock cycle, making correct arbitrary composition of simulator components impossible and limiting the amount of hardware concurrency which can be achieved. Latency-Insensitive Bounded …

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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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Comfort And Compatibility Of Silicone Hydrogel Contact Lenses, Ngai Keung Tam May 2013

Comfort And Compatibility Of Silicone Hydrogel Contact Lenses, Ngai Keung Tam

Theses and Dissertations

Silicone Hydrogel (SiHy) contact lenses are highly successful compared to previous soft lenses; they were developed to provide superior oxygen permeability. However, the hydrophobic natures of the silicone segments enhance lipid sorption which may diminish the lens surface wettability, clarity and comfort. While lens and lens care product are designed to remove lipid deposition, there is lack of experimental evidence to evaluate the actual performances with respect to lipid removal. An in vitro model using an artificial tear fluid containing radiolabeled lipids was employed in this thesis research to evaluate the efficacy of different multi-purpose lens care solutions in removing …

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A Polarizable Reactive Force Field For Water To Enable Molecular Dynamics Simulations Of Proton Transport, Abhishek Asthana, Dean R. Wheeler May 2013

A Polarizable Reactive Force Field For Water To Enable Molecular Dynamics Simulations Of Proton Transport, Abhishek Asthana, Dean R. Wheeler

Faculty Publications

A new polarizable water model is developed for molecular dynamics (MD) simulations of the proton transport process. The interatomic potential model has three important submodels corresponding to electrostatic interactions, making and breaking of covalent bonds, and treatment of electron exchange and correlation through a van der Waals potential. A polarizable diffuse charge density function was used to describe Coulombic interactions between atoms. Most of the model parameters were obtained from ab initio data for a lone water molecule. Molecules respond realistically to their electrochemical environment by the use of coupled fluctuating charge and fluctuating dipole dynamics, which controlled the charge …

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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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Modeling, Parameter Estimation, And Navigation Of Indoor Quadrotor Robots, Stephen C. Quebe Apr 2013

Modeling, Parameter Estimation, And Navigation Of Indoor Quadrotor Robots, Stephen C. Quebe

Theses and Dissertations

This thesis discusses topics relevant to indoor unmanned quadrotor navigation and control. These topics include: quadrotor modeling, sensor modeling, quadrotor parameter estimation, sensor calibration, quadrotor state estimation using onboard sensors, and cooperative GPS navigation. Modeling the quadrotor, sensor modeling, and parameter estimation are essential components for quadrotor navigation and control. This thesis investigates prior work and organizes a wide variety of models and calibration methods that enable indoor unmanned quadrotor flight. Quadrotor parameter estimation using a particle filter is a contribution that extends current research in the area. This contribution is novel in that it applies the particle filter specifically …

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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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A Methodology For The Extraction Of Design Principles For Unfamiliar Markets, Robert D. Campbell Apr 2013

A Methodology For The Extraction Of Design Principles For Unfamiliar Markets, Robert D. Campbell

Theses and Dissertations

Successful product design focuses on design principles that are relevant to a target market. Consequently, the better these principles are understood and used, the higher the likelihood that resulting products will be well-received in that market. This thesis presents a method for extracting market-specific design principles for any market. The method employs user/designer-described characteristics of products within a market to extract the design principles specific to that market. The method generalizes the product characteristics, seeks to discover design decisions that could have resulted in those characteristics, and then extracts the underlying design principles. To demonstrate the ability of the method …

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Fully Compliant Mechanisms For Bearing Subtraction In Robotics And Space Applications, Ezekiel G. Merriam Apr 2013

Fully Compliant Mechanisms For Bearing Subtraction In Robotics And Space Applications, Ezekiel G. Merriam

Theses and Dissertations

Robotics and space applications represent areas where compliant mechanisms can continue to make a significant impact by reducing costs and weight while improving performance. Because of the nature of these applications, a common need is for bearing replacement mechanisms, or mechanisms that perform the function of a bearing without the complexity and failure modes associated with bearings. Static balancing is a design strategy that attempts to reduce the actuation effort of a mechanism, and has been applied to compliant mechanisms in some applications. Monolithic construction, especially by means of 3D printing technology, is a strategy whereby the mechanism links and …

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Revisiting Blob Theory For Dna Diffusivity In Slitlike Confinement, Liang Dai, Douglas R. Tree, Johan R. C. Van Der Maarel, Kevin D. Dorfman, Patrick S. Doyle Apr 2013

Revisiting Blob Theory For Dna Diffusivity In Slitlike Confinement, Liang Dai, Douglas R. Tree, Johan R. C. Van Der Maarel, Kevin D. Dorfman, Patrick S. Doyle

Faculty Publications

Blob theory has been widely applied to describe polymer conformations and dynamics in nanoconfinement. In slit confinement, blob theory predicts a scaling exponent of 2/3 for polymer diffusivity as a function of slit height, yet a large body of experimental studies using DNA produce a scaling exponent significantly less than 2/3. In this work, we develop a theory that predicts that this discrepancy occurs because the segment correlation function for a semiflexible chain such as DNA does not follow the Flory exponent for length scales smaller than the persistence length. We show that these short length scale effects contribute significantly …

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Influence Of Tissue Stiffness Asymmetry On Human Vocal Fold Vibration, Kimberly Stevens, Dr. Scott Thomson Apr 2013

Influence Of Tissue Stiffness Asymmetry On Human Vocal Fold Vibration, Kimberly Stevens, Dr. Scott Thomson

Journal of Undergraduate Research

The flow-induced vibration of the human vocal folds produces the sound for voiced speech and singing. The vocal folds consist of two folds of tissue, one on each side of the larynx, that are nominally symmetric in terms of shape, composition, and stiffness. However, several voice disorders, including vocal fold scarring and inflammation, cause severe asymmetry in vocal fold tissue properties. The asymmetry can lead to irregular vocal fold vibration and subsequent decrease in voice quality. A more accurate understanding of the effect of vocal fold asymmetry can aid in the development of improved clinical care of the human voice. …

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Measurement Of Wing Loads During Flapping Flight, Ryan Anderson, Dr. Mark Colton Apr 2013

Measurement Of Wing Loads During Flapping Flight, Ryan Anderson, Dr. Mark Colton

Journal of Undergraduate Research

Ongoing research at BYU with the Flapping Flight Research Group (FFRG) is aimed at uncovering the physics behind flapping flight. Discoveries in this field could produce new aircraft designs and technolo- gies, as well as broaden our understanding of natural phenomena. One ambition of the FFRG is to quanti- fy (as determined by lift and thrust) wing trajectories followed during flight. To achieve this quantifica- tion, a precise sensor is necessary to record the lift and thrust produced during each flap.

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Assessing The Impact Of The Approximations Used In The Development Of The Pulsed Laser Method For Measuring Thermal Diffusivity, Trevor Terrill, Dr. Matthew Jones Apr 2013

Assessing The Impact Of The Approximations Used In The Development Of The Pulsed Laser Method For Measuring Thermal Diffusivity, Trevor Terrill, Dr. Matthew Jones

Journal of Undergraduate Research

The purpose of this project was to conduct a rigorous investigation of each of the approximations made in the development of the pulsed laser method for measuring the thermal diffusivity. Thermal conductivity is an important engineering parameter, but measuring it directly is difficult. In common engineering practice, the thermal diffusivity, specific heat, and density are measured, and the thermal conductivity is calculated from these properties. The pulsed laser or flash method is commonly employed to measure the thermal diffusivity, but it contains many restrictive approximations that are difficult to satisfy in practice. This project investigated the significance of each of …

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Investigation And Development Of Of Pyrometer Coating, Weston Baxter, Dr. Dale Tree Apr 2013

Investigation And Development Of Of Pyrometer Coating, Weston Baxter, Dr. Dale Tree

Journal of Undergraduate Research

This project aimed to produce and test an opaque surface on an optical fiber tip that will survive temperatures up to 3000 K. The optical fiber is to be used to measure flame temperature in oxy-coal and other combustion processes.

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Enhancing In Vitro Production Of Exotic Proteins Utilizing Linear Dna Templates, Savannah Herdegen, Dr. Brad Bundy Apr 2013

Enhancing In Vitro Production Of Exotic Proteins Utilizing Linear Dna Templates, Savannah Herdegen, Dr. Brad Bundy

Journal of Undergraduate Research

[Final report posting is embargoed pending publication.]

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New Capabilities In Large-Scale Models In Computational Biology, Casey Abbott, Dr. John Hedengren Apr 2013

New Capabilities In Large-Scale Models In Computational Biology, Casey Abbott, Dr. John Hedengren

Journal of Undergraduate Research

Advances in biomedical research have lead to an increase of experimental data to be interpreted in the context of reaction pathways, molecular transport, and population dynamics. Kinetic modeling is one way employed to interpret this data and is used in the pharmaceutical industry in developing clinical trials for new medications [1]. One collection of kinetic models is built on the System Biology Markup Language (SBML). Many of these models have detailed reaction metabolic pathways that describe biological systems, including cause and effect relationships in the human body. While simulations of these biological systems have been successfully applied for many years, …

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An Alternative Method To Prepare Cobalt Catalysts Using Salt Precursors, Trevor Seegmiller, Dr. Calvin Bartholomew Apr 2013

An Alternative Method To Prepare Cobalt Catalysts Using Salt Precursors, Trevor Seegmiller, Dr. Calvin Bartholomew

Journal of Undergraduate Research

Fischer-Tropsch synthesis (FTS) is the process for converting syngas (carbon monoxide and hydrogen) into liquid fuels such as gasoline and diesel. A cobalt or iron catalyst is required for the process. Cobalt catalysts have the highest effectiveness and stability in FTS; however, they are more expensive due to higher materials cost as well as the time-consuming and complex processes generally associated with manufacture.

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Instrumentation And Monitoring Of Concrete Bridge Decks: Moisture, Temperature, And Electrical Conductivity, Tenli Waters, Dr. Spencer Guthrie Apr 2013

Instrumentation And Monitoring Of Concrete Bridge Decks: Moisture, Temperature, And Electrical Conductivity, Tenli Waters, Dr. Spencer Guthrie

Journal of Undergraduate Research

The purpose of this report is to give the results of research conducted to measure the extent of internal curing occurring in the field in concrete bridge decks constructed using lightweight concrete compared to conventional concrete. With permission from bridge engineers at the Utah Department of Transportation and in cooperation with personnel at Provo River Constructors and Raba Kistner Infrastructure, Inc., we used sensors donated by Decagon Devices to monitor moisture content, temperature, and electrical conductivity in four bridge decks located in Utah County along the I-15 corridor: 400 South, 400 North, 800 North, and Geneva Road. The bridge decks …

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Scos Calibration And Filtering For Hpm Field Measurement, Bradley Whitaker, Dr. Stephen Schultz Apr 2013

Scos Calibration And Filtering For Hpm Field Measurement, Bradley Whitaker, Dr. Stephen Schultz

Journal of Undergraduate Research

High power microwave (HPM) weapons create large electric and magnetic fields with the purpose of disrupting electronic equipment. In order to protect electronics, the interaction between the equipment and the electromagnetic fields must be characterized. This requires a noninvasive sensor that can detect large electromagnetic fields and the sensing area needs to be in close proximity to the target electronics. However, to serve as a reliable measurement tool, the sensor must neither cause electromagnetic interference of its own nor disrupt the electric field it measures. Finally, the sensor must not be sensitive to electric and magnetic field interference outside the …

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Power Harvesting System For More Efficient, Cleaner Burning Cookstoves, Suman Pokharel, Dr. Matthew Jones Apr 2013

Power Harvesting System For More Efficient, Cleaner Burning Cookstoves, Suman Pokharel, Dr. Matthew Jones

Journal of Undergraduate Research

Each day more than 2 billion people cook using open fires or fires in primitive cook stoves that are fueled with biomass (wood, straw, crop waste, dung, etc…). These fires pollute homes and the environment, leading to serious health problems and contributing to global climate change. Additionally, fuel must be purchased at relatively high prices, or many hours are required to gather sufficient fuel each day. High fuel costs add in the limited financial resources, and collecting for fuel limits time available for education or other economically productive activities.

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Development Of A Fuel-Efficient Stove To Reduce Particulate Emissions, Geoffrey Lemon, Dr. Randy Lewis Apr 2013

Development Of A Fuel-Efficient Stove To Reduce Particulate Emissions, Geoffrey Lemon, Dr. Randy Lewis

Journal of Undergraduate Research

According to the World Health Organization, one of the leading causes of death in developing countries is respiratory disease, caused by inhalation of particulates from cooking stoves.1 With this challenge in mind, our team of interdisciplinary engineering students worked for over two semesters on designing and implementing a more effective stove for the people in Matinga, Peru. With the help and feedback of faculty members and other teams within our Global Engineering Outreach class, we chose to design a modified “rocket stove.” This design was chosen to more completely combust the fuel, producing a much cleaner burning fire.

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Silver Flash: A Mems Memory Device, John Stout, Dr. Aaron Hawkins Apr 2013

Silver Flash: A Mems Memory Device, John Stout, Dr. Aaron Hawkins

Journal of Undergraduate Research

The silver flash project is an effort to create a reliable, MEMs based memory device. As a joint electrical and mechanical structure these devices offer several advantages over the traditional NAND flash memory currently found in phones, mp3 players, and USB memory drives. The silver flash project uses standard silicon-processing materials and processes to build a device that should have a long lifespan and continue to function under extreme conditions.

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Incorporating Cyberbullying Prevention Curriculum In Technology Classrooms, Andrew Jackson, Dr. Geoff Wright Apr 2013

Incorporating Cyberbullying Prevention Curriculum In Technology Classrooms, Andrew Jackson, Dr. Geoff Wright

Journal of Undergraduate Research

With the advancement of communication technology and the increasing influence it has in our lives, the prevalence of a new intimidation tactic, cyberbullying, is multiplying. Recent studies cite that between 25% and 46% of adolescents are victims of cyberbullying or online harassment (Li, 2006; Palfrey et al., 2010). At present there is limited access to a cyberbullying prevention curriculum for educators; cyberbullying prevention resources have not been synthesized into useable curriculum.

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