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Full-Text Articles in Engineering

Estimated Instability And Breaking Of Internal Waves Due To Time-Dependent Shear, Leonardo A. Latorre Mar 2012

Estimated Instability And Breaking Of Internal Waves Due To Time-Dependent Shear, Leonardo A. Latorre

Theses and Dissertations

The effects of propagation of a short internal gravity wave through an inertia wave on internal wave stability is analyzed and parameterized. The interactions are specifically between a short wave packet and a large inertia wave packet. The short wave packet is a wave bounded with a Gaussian envelope with high frequencies and scales in the hundreds of meters horizontally and tens of meters vertically. The inertia wave packet is also an enveloped wave but with frequencies close to the rotation of the earth and scales in the thousands of meters in the horizontal and hundreds of meters in the …

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Numerical Investigation Of Internal Wave-Vortex Dipole Interactions, Tyler D. Blackhurst Mar 2012

Numerical Investigation Of Internal Wave-Vortex Dipole Interactions, Tyler D. Blackhurst

Theses and Dissertations

Three-dimensional linear ray theory is used to investigate internal waves interacting with a Lamb-Chaplygin pancake vortex dipole. These interactions involve waves propagating in the same (co-propagating) and opposite (counter-propagating) horizontal directions as the dipole translation. Co-propagating internal waves in the vertical symmetry plane between the vortices of the dipole can approach critical levels where the wave energy is absorbed by the dipole or where the waves are overturned and possibly break. As wave breaking cannot be simulated with this linear model, changes in wave steepness are calculated to aid in estimating the onset of breaking. Counter-propagating internal waves in the …

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Buckling Failure Boundary For Cylindrical Tubes In Pure Bending, Daniel Peter Miller Mar 2012

Buckling Failure Boundary For Cylindrical Tubes In Pure Bending, Daniel Peter Miller

Theses and Dissertations

Bending of thin-walled tubing to a prescribed bend radius is typically performed by bending it around a mandrel of the desired bend radius, corrected for spring back. By eliminating the mandrel, costly setup time would be reduced, permitting multiple change of radius during a production run, and even intermixing different products on the same line. The principal challenge is to avoid buckling, as the mandrel and shoe are generally shaped to enclose the tube while bending. Without the shaped mandrel, buckling will likely occur sooner, that is, at larger bend radii. A test apparatus has been built for arborless bending. …

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Application Of High Resolution Electron Backscatter Diffraction(Hr-Ebsd) Techniques To Twinning Deformation Mechanism In Az31 Magnesium Alloy, Ali Khosravani Mar 2012

Application Of High Resolution Electron Backscatter Diffraction(Hr-Ebsd) Techniques To Twinning Deformation Mechanism In Az31 Magnesium Alloy, Ali Khosravani

Theses and Dissertations

The application of high resolution electron backscatter diffraction (HR-EBSD) techniques has been used in order to study the evolution of geometrically necessary dislocation (GND). The tested materials were taken from AZ31 magnesium sheet which had strong basal texture. Because of low symmetry of the magnesium crystal lattice, the von Mises criteria cannot be satisfied by the three independent, easily activated, basal slips. The strain along the c-axis of the crystal must be accommodated by either twinning and/or slip systems. HR-EBSD data was taken in order to investigate these phenomena. The HR-EBSD results were post processed in order to resolve total …

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Failure Mechanisms And Texture Evolution Of Wrought Az31b Magnesium At Temperatures Ranging From 25 C To 125 C, Jonathan Michael Scott Mar 2012

Failure Mechanisms And Texture Evolution Of Wrought Az31b Magnesium At Temperatures Ranging From 25 C To 125 C, Jonathan Michael Scott

Theses and Dissertations

Failure mechanisms were studied in wrought AZ31B magnesium alloy under different strain paths and various temperatures. Optical micrographs were used to observe the formation of shear bands and regions of high twin density in samples strained under uniaxial, biaxial and plane strain conditions. Interrupted testing at 4% effective strain increments until failure was used to observe the evolution of the microstructure. Results showed that shear bands with a high percentage of twinned grains appeared early in the samples strained under biaxial or plane strain tension. These bands are similar to the failure region in uniaxial tension specimens. A forming limit …

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Damage Tolerance Of Unidirectional Carbon And Fiberglass Composites With Aramid Sleeves, Charles Andrew Sika Mar 2012

Damage Tolerance Of Unidirectional Carbon And Fiberglass Composites With Aramid Sleeves, Charles Andrew Sika

Theses and Dissertations

Unidirectional carbon fiber and fiberglass epoxy composite elements consolidated with aramid sleeves were radially impacted at 5 J (3.7 ft-lbs) and 10 J (7.4 ft-lbs), tested under compression, and compared to undamaged control specimens. These structural elements represent local members of open three-dimensional composite lattice structures (e.g., based on isogrid or IsoTruss® technologies). Advanced three-dimensional braiding techniques were used to continuously fabricate these specimens. The unidirectional core specimens, 8 mm (5/16 in) in diameter, were manufactured with various sleeve patterns. Bi-directional braided sleeves and unidirectional spiral sleeves ranged from a nominal full to half coverage. These specimens were tested for …

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Evaluating Climate Change Effects In Two Contrasting Reservoirs Using Two-Dimensional Water Quality And Hydrodynamic Models, Oliver Obregon Mar 2012

Evaluating Climate Change Effects In Two Contrasting Reservoirs Using Two-Dimensional Water Quality And Hydrodynamic Models, Oliver Obregon

Theses and Dissertations

I analyzed and compared impacts from global climate change (GCC) and land use change to Deer Creek (United States) a temperate reservoir and Aguamilpa (Mexico), a tropical reservoir by using calibrated CE-QUAL-W2 (W2) water quality and hydrodynamic models based on field data over an extended time period. I evaluated and compared the sensitivity to predicted GCC and land use changes. I individually evaluated changes to air temperature (TAIR), inflow rates (Q), and nutrient loads (PO4-P and NO3-NO2-N) followed by analysis of worst case scenarios. I developed analysis methods using indexes to represent the total …

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A Methodology For Strategically Designing Physical Products That Are Naturally Resistant To Reverse Engineering, Stephen P. Harston Mar 2012

A Methodology For Strategically Designing Physical Products That Are Naturally Resistant To Reverse Engineering, Stephen P. Harston

Theses and Dissertations

Reverse engineering - defined as extracting information about a product from the product itself - is a design tactic commonly used in industry from competitive benchmarking to product imitation. While reverse engineering is a legitimate practice - as long as the product was legally obtained - innovative products are often reverse engineered at the expense of the pioneering company. However, by designing products with built-in barriers to reverse engineering, competitors are no longer able to effectively extract critical information from the product of interest. Enabling the quantification of barriers to reverse engineering, this dissertation presents a set of metrics and …

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Study Of Water Quality Of Utah Lake Tributaries And The Jordan River Outlet For The Calibration Of The Utah Lake Water Salinity Model (Lksim), Gordon Killarney Liljenquist Mar 2012

Study Of Water Quality Of Utah Lake Tributaries And The Jordan River Outlet For The Calibration Of The Utah Lake Water Salinity Model (Lksim), Gordon Killarney Liljenquist

Theses and Dissertations

The water quality of Utah Lake is of great importance to agriculture, recreation, and wildlife. The Utah Lake Simulation Model (LKSIM) was created to accurately predict changes in water quality parameters. However, a potential limitation of LKSIM is the age of the underlying data which was gathered from 1930 to 1980. New sample data were collected from March 2009 through May 2011. Samples were taken from 13 tributaries, the Jordan River Outlet, and various wastewater treatment plants (WWTP). Upon dividing the collected data points into seasons and plotting them in Microsoft Excel, trendline equations were produced. These equations correlated TDS …

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Smart Phone-Based Indoor Guidance System For The Visually Impaired, Brandon Lee Taylor Mar 2012

Smart Phone-Based Indoor Guidance System For The Visually Impaired, Brandon Lee Taylor

Theses and Dissertations

A smart phone camera based indoor guidance system to aid the visually impaired is presented. Most proposed systems for aiding the visually impaired with indoor navigation are not feasible for widespread use due to cost, usability, or portability. We use a smart phone vision based system to create an indoor guidance system that is simple, accessible, inexpensive, and discrete to aid the visually impaired to navigate unfamiliar environments such as public buildings. The system consists of a smart phone and a server. The smart phone transmits pictures of the user's location to the server. The server processes the images and …

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High Speed Friction Stir Spot Welding On Dp 980 Steel:Joint Properties And Tool Wear, Nathan David Saunders Mar 2012

High Speed Friction Stir Spot Welding On Dp 980 Steel:Joint Properties And Tool Wear, Nathan David Saunders

Theses and Dissertations

With the desire to improve passenger safety and fuel efficiency, Ultra High Strength Steels (UHSS) have been developed for use in the automotive industry. UHSS are high strength steels with high ductility and strength. DP 980 is one of these UHSS being applied in automobile manufacturing. DP 980 is difficult to join with Resistance Spot Welding (RSW) because of the high carbon content and alloying in this material. The weld becomes brittle when it solidifies during the welding process. With the desire and motivation of widely using UHSS, new welding processes are needed to be developed in order to effectively …

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The Effects Of Micro- And Macro-Scale Geometric Parameters On Performance Of The Pleated Aerosol Filters, Shahryar Fotovati Mar 2012

The Effects Of Micro- And Macro-Scale Geometric Parameters On Performance Of The Pleated Aerosol Filters, Shahryar Fotovati

Theses and Dissertations

While most filters are made of pleated fibrous media, almost all existing theories of aerosol filtration are developed for flat media placed perpendicular to the air flow. Expressions developed for flat sheet media do not provide accurate information directly useful for designing a pleated filter, and therefore, most progress made in developing pleated filters is based on empiricism. This study is aimed at establishing an enabling knowledge that allows for a better design and optimization of pleated aerosol filters. This study is focused on developing a predictive simulation method that accounts for the influence of a filter’s micro-scale geometric parameters, …

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Mitigation Of Sea Ice Contamination In Quikscat Wind Retrieval, Weston Jay Hullinger Mar 2012

Mitigation Of Sea Ice Contamination In Quikscat Wind Retrieval, Weston Jay Hullinger

Theses and Dissertations

Satellite borne radar scatterometers provide frequent estimates of near surface wind vectors over the Earth's oceans. However in the polar oceans, the presence of sea ice in or near the measurement footprint can adversely a ect scatterometer measurements resulting in inaccurate wind estimates. Currently, such ice contamination is mitigated by discarding measurements within 50 km of detected sea ice. This approach is imperfect and causes loss of coverage. This thesis presents a new algorithm which detects ice-contaminated measurements based on a metric called the Ice Contribution Ratio (ICR) which measures the spatial ice contribution for each measurement. The ICR calculation …

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The Effect Of The Engineering Design Process On The Critical Thinking Skills Of High School Students, Heather Ure Mar 2012

The Effect Of The Engineering Design Process On The Critical Thinking Skills Of High School Students, Heather Ure

Theses and Dissertations

The purpose of the research reported here was to determine the impact learning the engineering design process (EDP) would have on the critical thinking skills of high school physics students. An EDP unit was conducted with 5 classes of high school physics students in grades 10-12 over 1 month. The EDP unit's curriculum allowed for the gradual release of responsibility as students became more familiar with the EDP and more consistent in using it. The six steps used in this EDP unit were Ask, Imagine, Plan, Create, Test, and Improve. The Watson-Glaser Critical Thinking Appraisal was given as a pre- …

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Maintenance Operations Degradation Of Airfield Pavement Markings, John C. Jaszkowiak Mar 2012

Maintenance Operations Degradation Of Airfield Pavement Markings, John C. Jaszkowiak

Theses and Dissertations

Pavement markings are an essential element in the navigational aids subsystem for any airfield. Most airfields still use waterborne paint as the primary marking material, although there are other materials in use on roadways that airfield managers could use to save time and money. An airfield experiences a host of maintenance operations that cause degradation of the pavement markings. Of particular concern are rubber removal operations, sweeping operations, and snowplowing operations. This research focuses on chemical rubber removal operations and sweeping operations. The study evaluates waterborne paint markings and thermoplastic marking strips to determine if these marking materials perform differently …

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Plume Characterization Of Busek 600w Hall Thruster, Duc Minh Bui Mar 2012

Plume Characterization Of Busek 600w Hall Thruster, Duc Minh Bui

Theses and Dissertations

The BHT-600W thruster has a high potential to place on various commercial and military satellites as a main propulsion system for orbit maintenance and orbit maneuvering. Therefore, the thruster's performance characteristics and parameters were evaluated for various operating conditions. These parameters include thrust, power consumption, mass flow rate, and efficiencies. Various plume properties were measured and characterized for the thruster to include exhaust beam profile and ion species distribution. The faraday probe was used to examine the thruster plume current density while the ion species fractions were determined by the ExB probe. The inverted pendulum thrust stand was also utilized …

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Application Of Subjective Logic To Vortex Core Line Extraction And Tracking From Unsteady Computational Fluid Dynamics Simulations, Ryan Phillip Shaw Mar 2012

Application Of Subjective Logic To Vortex Core Line Extraction And Tracking From Unsteady Computational Fluid Dynamics Simulations, Ryan Phillip Shaw

Theses and Dissertations

Presented here is a novel tool to extract and track believable vortex core lines from unsteady Computational Fluid Dynamics data sets using multiple feature extraction algorithms. Existing work explored the possibility of extracting features concurrent with a running simulation using intelligent software agents, combining multiple algorithms' capabilities using subjective logic. This work modifies the steady-state approach to work with unsteady fluid dynamics and is designed to work within the Concurrent Agent-enabled Feature Extraction concept. Each agent's belief tuple is quantified using a predefined set of information. The information and functions necessary to set each component in each agent's belief tuple …

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Mathematical Framework For Early System Design Validation Using Multidisciplinary System Models, Bradley Jared Larson Mar 2012

Mathematical Framework For Early System Design Validation Using Multidisciplinary System Models, Bradley Jared Larson

Theses and Dissertations

A significant challenge in the design of multidisciplinary systems (e.g., airplanes, robots, cell phones) is to predict the effects of design decisions at the time these decisions are being made early in the design process. These predictions are used to choose among design options and to validate design decisions. System behavioral models, which predict a system's response to stimulus, provide an analytical method for evaluating a system's behavior. Because multidisciplinary systems contain many different types of components that have diverse interactions, system behavioral models are difficult to develop early in system design and are challenging to maintain as designs are …

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Hardware And Software Fault-Tolerance Of Softcore Processors Implemented In Sram-Based Fpgas, Nathaniel Hatley Rollins Mar 2012

Hardware And Software Fault-Tolerance Of Softcore Processors Implemented In Sram-Based Fpgas, Nathaniel Hatley Rollins

Theses and Dissertations

Softcore processors are an attractive alternative to using expensive radiation-hardened processors for space-based applications. Since they can be implemented in the latest SRAM-based FPGA technologies, they are fast, flexible and significantly less expensive. However, unlike ASIC-based processors, the logic and routing of a softcore processor are vulnerable to the effects of single-event upsets (SEUs). To protect softcore processors from SEUs, this dissertation explores the processor design-space for the LEON3 softcore processor implemented in a commercial SRAM-based FPGA. The traditional mitigation techniques of triple modular redundancy (TMR) and duplication with compare (DWC) and checkpointing provide reliability to a softcore processor at …

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Investigation And Implementation Of A Robust Temperature Control Algorithm For Friction Stir Welding, Kenneth A. Ross Mar 2012

Investigation And Implementation Of A Robust Temperature Control Algorithm For Friction Stir Welding, Kenneth A. Ross

Theses and Dissertations

In friction stir welding, the temperature of the process zone affects the properties of the resulting weld and has a dramatic effect on tool life in PCBN (polycrystalline cubic boron nitride) tools. Therefore an active control system that changes process parameters to control weld temperature is desirable. Mayfield and Sorensen proposed a two-stage control model that contains an inner loop that controls the spindle speed to keep power constant and an outer loop for setting the desired power based on weld temperature. This work contains the analysis and implementation of a temperature control method based on their work. This research …

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Low-Photoluminescence Hollow Waveguide Platforms For High-Sensitivity Integrated Optical Sensors, Yue Zhao Mar 2012

Low-Photoluminescence Hollow Waveguide Platforms For High-Sensitivity Integrated Optical Sensors, Yue Zhao

Theses and Dissertations

This dissertation presents research on the fabrication of optofluidic sensor platforms, which consist of integrated hollow waveguides and solid waveguides. Antiresonant reflecting optical waveguides (ARROWs) filled with liquids or gases, can be used for high-sensitivity sensing in applications of biotechnology, chemical synthesis, and analytical chemistry. The fabrication method developed for integrated ARROW sensing platforms utilizes standard microfabrication processes and materials. Dielectric cladding layers are deposited on a silicon wafer using plasma-enhanced chemical vapor deposition (PECVD) or sputtering. A sacrificial material is then patterned over the bottom cladding layers by photolithography. Additional dielectric layers are deposited around the core, forming the …

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Feature Construction Using Evolution-Constructed Features For General Object Recognition, Kirt D. Lillywhite Mar 2012

Feature Construction Using Evolution-Constructed Features For General Object Recognition, Kirt D. Lillywhite

Theses and Dissertations

Object recognition is a well studied but extremely challenging field. Human detection is an especially important part of object recognition as it has played a role in machine and human interaction, biometrics, unmanned vehicles, as well as tracking and surveillance. We first present a hardware implementation of the successful Histograms of Oriented Gradients (HOG) method for human detection. The implementation significantly speeds up the method achieving 38 frames a second on VGA video while testing 11,160 sliding windows per frame. The accuracy remains comparable to the CPU implementation. Analysis of the HOG method and other popular object recognition methods led …

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A Programmable Liquid Collimator For Both Coded Aperture Adaptive Imaging And Multiplexed Compton Scatter Tomography, Jack G. M. Fitzgerald Mar 2012

A Programmable Liquid Collimator For Both Coded Aperture Adaptive Imaging And Multiplexed Compton Scatter Tomography, Jack G. M. Fitzgerald

Theses and Dissertations

A novel, fully reconfigurable collimator device for gamma-ray and X-ray imaging was built and tested as a coded aperture. The device consisted of 10x10, 5x5x5 mm3 chambers. Each chamber either was filled with an attenuating liquid, stopping photons, or evacuated of the attenuating liquid, allowing the photons to pass through. As the pattern of on and off chambers was manipulated, different, semi-independent views of the gamma-ray source were found. Noise in reconstructed images decreased in all tests. Image reconstruction was performed with correlation methods and Maximum Likelihood Expectation Maximization (ML-EM). Using 10 mask patterns, the signal-to-noise ratio (SNR) in …

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Real-Time Stereo Vision For Resource Limited Systems, Beau J. Tippetts Mar 2012

Real-Time Stereo Vision For Resource Limited Systems, Beau J. Tippetts

Theses and Dissertations

A significant amount of research in the field of stereo vision has been published in the past decade. Considerable progress has been made in improving accuracy of results as well as achieving real-time performance in obtaining those results. Although much of the literature does not address it, many applications are sensitive to the tradeoff between accuracy and speed that exists among stereo vision algorithms. Overall, this work aims to organize existing efforts and encourage new ones in the development of stereo vision algorithms for resource limited systems. It does this through a review of the status quo as well as …

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Agent Based Modeling And Simulation Framework For Supply Chain Risk Management, Tiffany J. Harper Feb 2012

Agent Based Modeling And Simulation Framework For Supply Chain Risk Management, Tiffany J. Harper

Theses and Dissertations

This research develops a flexible agent-based modeling and simulation (ABMS) framework for supply chain risk management with significant enhancements to standard ABMS methods and supply chain risk modeling. Our framework starts with the use of software agents to gather and process input data for use in our simulation model. For our simulation model, we extend an existing mathematical framework for discrete event simulation (DES) to ABMS and then implement the concepts of variable resolution modeling from the DES domain to ABMS and provide further guidelines for aggregation and disaggregation of supply chain models. Existing supply chain risk management research focuses …

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Integration Of Massive Multiplayer Online Role-Playing Games Client-Server Architectures With Collaborative Multi-User Engineering Cax Tools, Joshua D. Winn Feb 2012

Integration Of Massive Multiplayer Online Role-Playing Games Client-Server Architectures With Collaborative Multi-User Engineering Cax Tools, Joshua D. Winn

Theses and Dissertations

This research presents a new method for integrating client server architectures that are used for the development of Massive Online Role Playing Games (MMORPG) into multi-user engineering software tools. The new method creates a new architecture named CAx Connect by changing the client-pull-server communication pipeline to a server-push-client communication pipeline, effectively reducing the amount of bandwidth consumed and allowing these tools to utilize multiple server processors for complex calculations. This method was used on the new NX Connect multi-user CAx prototype developed at BYU. The new method provides a road map to further implement this architecture and its services into …

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Modeling Small Unmanned Aerial System Mishaps Using Logistics Regression And Artificial Neural Networks, Sean E. Wolf Feb 2012

Modeling Small Unmanned Aerial System Mishaps Using Logistics Regression And Artificial Neural Networks, Sean E. Wolf

Theses and Dissertations

A dataset of 854 small unmanned aerial system (SUAS) flight experiments from 2005-2009 is analyzed to determine significant factors that contribute to mishaps. The data from 29 airframes of different designs and technology readiness levels were aggregated. 20 measured parameters from each flight experiment are investigated, including wind speed, pilot experience, number of prior flights, pilot currency, etc. Outcomes of failures (loss of flight data) and damage (injury to airframe) are classified by logistic regression modeling and artificial neural network analysis. From the analysis, it can be concluded that SUAS damage is a random event that cannot be predicted with …

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Determination Of Effective Training Methods To Learn A Laparoscopic Camera Navigation Task Under Stressful Environments, Devnath Vasudevan Feb 2012

Determination Of Effective Training Methods To Learn A Laparoscopic Camera Navigation Task Under Stressful Environments, Devnath Vasudevan

Theses and Dissertations

Stress in surgical environment is generally very high and can result in performance degradation increasing patient risk .Current Training systems for learning minimally invasive surgical skills do not consider the component of stress in their training model. In this study the focus was on developing alternative training models that would allow the learner to effectively perform minimally invasive skill under stress. Two alternate training methods: 1) Training under stress until high performance levels and 2) training until high performance and low cognitive load are achieved were considered for this study. The control group consisted of training under no stress and …

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Traumatic Brain Injury Assessment Using The Integration Of Pattern Recognition Methods And Finite Element Analysis, Aghazadeh Babak Seyed Feb 2012

Traumatic Brain Injury Assessment Using The Integration Of Pattern Recognition Methods And Finite Element Analysis, Aghazadeh Babak Seyed

Theses and Dissertations

The overall goal of this research is to develop methods and algorithms to investigate the severity of Traumatic brain injury (TBI) and to estimate the intracranial pressure (ICP) level non-invasively. Brain x-ray computed tomography (CT) images and artificial intelligence methods are employed to estimate the level of ICP. Fully anisotropic complex wavelet transform features are proposed to extract directional textural features from brain images. Different feature selection and classification methods are tested to find the optimal feature vector and estimate the ICP using support vector regression. By using systematic feature extraction, selection and classification, promising results on ICP estimation are …

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Nanostructured Catalyst Materials For Next Generation Polymer Electrolyte Membrane (Pem) Fuel Cells, Wisam J. Khudhayer Feb 2012

Nanostructured Catalyst Materials For Next Generation Polymer Electrolyte Membrane (Pem) Fuel Cells, Wisam J. Khudhayer

Theses and Dissertations

Polymer electrolyte membrane (PEM) fuel cells are electrochemical energy conversion devices which have demonstrated great promise as future energy sources for electric vehicles, as they convert chemical energy to electrical energy with a significantly higher efficiency and lower environmental impact than in standard combustion processes. However, the commercialization of PEM fuel cells for transportation applications has been hindered by several factors such as high cost of Pt, low Pt utilization, poor long-term durability of the conventional PEM fuel cell catalyst (Pt nanoparticels supported on carbon black, Pt/C), and poor thermal and chemical stability of the electrocatalyst supports (carbon black). The …

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