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Articles 3571 - 3600 of 4850

Full-Text Articles in Engineering

Quantitative And Qualitative Results From Droplet Impingement Experiments On Superhydrophobic Surfaces With Micro-Ribs For Three Liquid Types, John T. Pearson Aug 2010

Quantitative And Qualitative Results From Droplet Impingement Experiments On Superhydrophobic Surfaces With Micro-Ribs For Three Liquid Types, John T. Pearson

Theses and Dissertations

Experiments were performed in which liquid droplets were videographically recorded impacting horizontal superhydrophobic surfaces. The superhydrophobic surfaces were micropatterned with alternating ribs and cavities and coated with a hydrophobic coating. The following surface types were also tested for comparison: smooth uncoated, micropatterned uncoated, and smooth coated surfaces. Three liquid types were used: pure water, ethanol, and a 50/50 water/glycerine mixture. Acquired data demonstrated that the maximum droplet spread diameter exhibited a greater Weber number dependence than that previously reported in the literature. The time delays between impact and maximum spread and between impact and ejection of a vertical jet were …


Thin Film Microfluidic And Nanofluidic Devices, Mark Noble Hamblin Aug 2010

Thin Film Microfluidic And Nanofluidic Devices, Mark Noble Hamblin

Theses and Dissertations

Lab-on-a-chip devices, also known as micro total analysis systems (μTAS), are implementations of chemical analysis systems on microchips. These systems can be fabricated using standard thin film processing techniques. Microfluidic and nanofluidic channels are fabricated in this work through sacrificial etching. Microchannels are fabricated utilizing cores made from AZ3330 and SU8 photoresist. Multi-channel electroosmotic (EO) pumps are evaluated and the accompanying channel zeta potentials are calculated. Capillary flow is studied as an effective filling mechanism for nanochannels. Experimental departure from the Washburn model is considered, where capillary flow rates lie within 10% to 70% of theoretical values. Nanochannels are fabricated …


An Adaptive Grid-Based All Hexahedral Meshing Algorithm Based On 2-Refinement, Jared D. Edgel Aug 2010

An Adaptive Grid-Based All Hexahedral Meshing Algorithm Based On 2-Refinement, Jared D. Edgel

Theses and Dissertations

Adaptive all-hexahedral meshing algorithms have many desirable features. These algorithms provide a mesh that is efficient for analysis by providing a high element density in specific locations, such as areas of high stress gradient or high curvature and reduced mesh density in other areas of less importance. In addition, inside-out hexahedral grid based schemes, using Cartesian structured grids for the base mesh, have shown great promise in accommodating automatic all-hexahedral algorithms. In these algorithms mesh refinement is generally used to capture geometric features. Unfortunately, most adaptive mesh generation algorithms employ a 3-refinement method. This method, although easy to employ, provides …


Energy Harvesting And Mission Effectiveness For Small Unmanned Air Vehicles, Mark J. Cutler, Timothy W. Mclain, Randal W. Beard, Brian Capozzi Aug 2010

Energy Harvesting And Mission Effectiveness For Small Unmanned Air Vehicles, Mark J. Cutler, Timothy W. Mclain, Randal W. Beard, Brian Capozzi

Faculty Publications

This paper explores the feasibility of improving unmanned air vehicle (UAV) mission effectiveness by extracting energy from the atmosphere. Specifically, we consider an aerial surveillance mission in the vicinity of a geographic ridge. Cross winds owing over the ridge produce regions of lift on the windward side that can be exploited to increase mission duration. Mission effectiveness is quantified using the seeability metric. Simulation results are presented for several observation target placements. Results indicate that seeability and imaging persistence can be improved by exploiting ridge lift. Simulations demonstrated that targets at ranges less than four times the ridge height were …


Using Design Of Experiments And Electron Backscatter Diffraction To Model Extended Plasticity Mechanisms In Friction Stir Welded Aisi 304l Stainless Steel, Benjamin D. Nelson Jul 2010

Using Design Of Experiments And Electron Backscatter Diffraction To Model Extended Plasticity Mechanisms In Friction Stir Welded Aisi 304l Stainless Steel, Benjamin D. Nelson

Theses and Dissertations

Extended plasticity mechanisms (EPM) allow a metal to undergo extended plastic deformation without failure. These mechanisms are responsible for the extended plastic deformation characteristic of hot working processes. In this thesis it is shown that electron backscatter diffraction (EBSD) is capable of detecting EPM artifacts in the final microstructure of AISI 304L stainless steel (304L). Results also indicate that dislocation cells form in hot worked AISI 304L stainless steel. Additionally, in this study EBSD data collection and analysis is used with a design of experiments approach to model the presence of EPM artifacts in the final microstructure of friction stir …


Numerical Simulation Of Atmospheric Internal Waves With Time-Dependent Critical Levels And Turning Points, Brian Patrick Casaday Jul 2010

Numerical Simulation Of Atmospheric Internal Waves With Time-Dependent Critical Levels And Turning Points, Brian Patrick Casaday

Theses and Dissertations

Just as water surface waves are found everywhere on the ocean's surface, internal waves are ubiquitous throughout the atmosphere. These waves constantly propagate and interact with other flows, but these interactions are difficult to observe due to inadequate current technology. Numerical simulations are often utilized in the study of internal waves. In this work, ray theory is used to numerically simulate the interaction of atmospheric internal waves with time-dependent and time-independent background flows, specifically the interaction of small-scale internal waves and large-scale inertial waves. Parameters such as initial wavenumbers and amplitudes of both small internal waves and inertial waves are …


An Experimental Investigation Of Friction Bit Joining In Az31 Magnesium And Advanced High-Strength Automotive Sheet Steel, Rebecca Gardner Jul 2010

An Experimental Investigation Of Friction Bit Joining In Az31 Magnesium And Advanced High-Strength Automotive Sheet Steel, Rebecca Gardner

Theses and Dissertations

Friction Bit Joining (FBJ) is a recently developed spot joining technology capable of joining dissimilar metals. A consumable bit cuts through the upper layer of metal to be joined, then friction welds to the lower layer. The bit then snaps off, leaving a flange. This research focuses on FBJ using DP980 or DP590 steel as the lower layer, AZ31 magnesium alloy as the top layer, and 4140 or 4130 steel as the bit material. In order to determine optimal settings for the magnesium/steel joints, experimentation was performed using a purpose-built computer controlled welding machine, varying factors such as rotational speeds, …


Analyzing The Effectiveness Of Safety Measures Using Bayesian Methods, Daniel J. Thurgood Jul 2010

Analyzing The Effectiveness Of Safety Measures Using Bayesian Methods, Daniel J. Thurgood

Theses and Dissertations

Recent research has shown that traditional safety evaluation methods have been inadequate in accurately determining the effectiveness of roadway safety measures. In recent years, advanced statistical methods have been utilized in traffic safety studies to more accurately determine the effectiveness of roadway safety measures. These methods, particularly hierarchical Bayesian statistical techniques, have the capabilities to account for the shortcomings of traditional methods. Hierarchical Bayesian modeling is a powerful tool for expressing rich statistical models that more fully reflect a given problem than a simpler model could. This paper uses a hierarchical Bayesian model to analyze the effectiveness of two types …


Impedance Imaging And Measurements By Micro Probes In Aqueous Environments, Tao Shang Jul 2010

Impedance Imaging And Measurements By Micro Probes In Aqueous Environments, Tao Shang

Theses and Dissertations

The dissertation presented here describes two research projects that may, at first glance, seem unrelated. Their unifying principle is the measurement of electrical impedance for the detection and analysis of biological materials. Impedance measurements have long been employed and studied in scientific fields, and the dissertation begins with a summary of historical methodology, applications, and terminology. Utilizing impedance measurements for microscopic imaging is the driving motivation for Scanning Impedance Imaging (SII). This technique manifests the distribution of electrical impedance inside biological tissues and is described after the dissertation's introduction. SII can provide micron-scale imaging resolution by scanning a shielded microprobe …


Influence Of Material And Geometric Parameters On The Flow-Induced Vibration Of Vocal Folds Models, Brian A. Pickup Jul 2010

Influence Of Material And Geometric Parameters On The Flow-Induced Vibration Of Vocal Folds Models, Brian A. Pickup

Theses and Dissertations

The vocal folds are an essential component of human speech production and communication. Advancements in voice research allow for improved voice disorder treatments. Since in vivo analysis of vocal fold function is limited, models have been developed to simulate vocal fold motion. In this research, synthetic and computational vocal fold models were used to investigate various aspects of vocal fold vibratory characteristics. A series of tests were performed to quantify the effect of varying material and geometric parameters on the models' flow-induced responses. First, the influence of asymmetric vocal fold stiffness on voice production was evaluated using life-sized, self-oscillating vocal …


Wireless Sensor Network Approach To Aeronautical Telemetry, Oluwasegun Babatunde Tinubi Jul 2010

Wireless Sensor Network Approach To Aeronautical Telemetry, Oluwasegun Babatunde Tinubi

Theses and Dissertations

Wireless sensor networks have become a rapidly growing research field in recent years. They are envisioned to have a wide range of applications in military, environmental and many other fields. We examine the performance of wireless sensor network applications to aeronautical telemetry. To date, test ranges have relied on a single telemetry ground station for the reception of packets from all air borne transmitters. We researched an alternate means of achieving this same goal with fewer resources. It is a well known fact that communication power and bandwidth are the most expensive commodities in wireless communications. The telemetry world is …


A New Eulerian-Based Double Continuity Model For Predicting The Evolution Of Pair Correlation Statistics Under Large Plastic Deformations, Sadegh Ahmadi Jul 2010

A New Eulerian-Based Double Continuity Model For Predicting The Evolution Of Pair Correlation Statistics Under Large Plastic Deformations, Sadegh Ahmadi

Theses and Dissertations

A new model using a double-continuity relation for predicting the evolution of pair-correlation functions (PCFs) is presented. The proposed model was developed using statistical continuum theory and is employed to predict the viscoplastic behavior of polycrystalline materials. This model was built based upon the continuity relations and a double divergence law that guarantees the conservation of both orientation and mass; and also satisfies the field equations (equilibrium, constitutive, and compatibility) at every point of the polycrystalline material throughout the deformation process. In the presented model, motion of particles in the real space and rotation of crystallographic orientations in the Euler …


Modeling, Design, And Testing Of Contact-Aided Compliant Mechanisms In Spinal Arthroplasty, Peter Andrew Halverson Jul 2010

Modeling, Design, And Testing Of Contact-Aided Compliant Mechanisms In Spinal Arthroplasty, Peter Andrew Halverson

Theses and Dissertations

Injury, instrumentation, or surgery may change the functional biomechanics of the spine. Spinal fusion, the current surgical treatment of choice, stabilizes the spine by rigid fixation, reducing spinal mobility at the cost of increased stress at adjacent levels. Recently, alternatives to spinal fusion have been investigated. One such alternative is total disc replacements. The current generation of total disc replacements (TDRs) focuses on restoring the quantity of motion. Recent studies indicate that the moment-rotation response and axis of rotation, or quality of motion (QOM), may have important implications in the health of adjacent segments as well as the health of …


A Computational Fluid Dynamics Feature Extraction Method Using Subjective Logic, Clifton H. Mortensen Jul 2010

A Computational Fluid Dynamics Feature Extraction Method Using Subjective Logic, Clifton H. Mortensen

Theses and Dissertations

Computational fluid dynamics simulations are advancing to correctly simulate highly complex fluid flow problems that can require weeks of computation on expensive high performance clusters. These simulations can generate terabytes of data and pose a severe challenge to a researcher analyzing the data. Presented in this document is a general method to extract computational fluid dynamics flow features concurrent with a simulation and as a post-processing step to drastically reduce researcher post-processing time. This general method uses software agents governed by subjective logic to make decisions about extracted features in converging and converged data sets. The software agents are designed …


An Examination Of Distributed Hydrologic Modeling Methods As Compared With Traditional Lumped Parameter Approaches, Murari Paudel Jul 2010

An Examination Of Distributed Hydrologic Modeling Methods As Compared With Traditional Lumped Parameter Approaches, Murari Paudel

Theses and Dissertations

Empirically based lumped hydrologic models have an extensive track record of use where as physically based, multi-dimensional distributed models are evolving for various engineering applications. Despite the availability of high resolution data, better computational resources and robust numerical methods, the usage of distributed models is still limited. The purpose of this research is to establish the credibility and usability of distributed hydrologic modeling tools of the United States Army Corps of Engineers (USACE) in order to promote the extended use of distributed models. Two of the USACE models were used as the modeling tools for the study, with Gridded Surface …


A Computationally-Assisted Methodology For Rapid Exploration Of Design Possibilities In Conceptual Design, Garrett J. Barnum Jul 2010

A Computationally-Assisted Methodology For Rapid Exploration Of Design Possibilities In Conceptual Design, Garrett J. Barnum

Theses and Dissertations

One of the most important decisions in the product development process is the selection of a promising design concept because of the large influence it has on the final product. A thorough search for the best design is a significant challenge to designers, who are trying to balance the objective and subjective performance of the designs they create. In this thesis, a computationally-assisted design methodology is developed and used in the early stages of design to more thoroughly search for designs that perform well according to objective physics-based models and subjective designer-specific preference-based models. The method presented herein uses an …


Corrosion-Related Gas Measurements And Analysis For A Suite Of Coals In Staged Pulverized Coal Combustion, Todd A. Reeder Jun 2010

Corrosion-Related Gas Measurements And Analysis For A Suite Of Coals In Staged Pulverized Coal Combustion, Todd A. Reeder

Theses and Dissertations

Eleven gas species, including CO, CO2, H2, H2O, H2S, HCl, NOX, O2, SO2, COS and SO3, were measured in a 150 kWth, staged, pulverized coal, down-fired combustor using a Fourier transform infrared (FTIR) spectrometer, gas chromatograph (GC), and a Horiba PG-250 5-gas analyzer. Additional gases such as HCN, NH3, CH4, and other hydrocarbons were also measured. Seven coals of varying rank and composition were investigated. Measurements were obtained in reducing (S.R. = 0.85) and oxidizing (S.R. = 1.15) conditions. In particular, sulfur- and chlorine-containing species including H2S, SO2, COS, SO3, and HCl are discussed. In the reducing zone, all four …


Best Practices For Dealing With Price Volatility In Utah's Residential Construction Market, James Packer Smith Jun 2010

Best Practices For Dealing With Price Volatility In Utah's Residential Construction Market, James Packer Smith

Theses and Dissertations

Price volatility is a consistent problem that affects all of the parties involved in the residential construction industry. The myriad factors that can have an impact on construction costs are such that it is extremely hard to anticipate upcoming changes in a timely and accurate way. When prices fluctuate during the course of a project, estimates become erroneous and completion of projects within expected budgets becomes difficult. Increasing prices typically leave contractors with the majority of the risk burden due to the enforceability of contracts that are likely to have been executed months prior. The risk associated with the owner's …


The Structure And Stability Of Alpha-Helical, Orthogonal-Bundle Proteins On Surfaces, Shuai Wei Jun 2010

The Structure And Stability Of Alpha-Helical, Orthogonal-Bundle Proteins On Surfaces, Shuai Wei

Theses and Dissertations

The interaction of proteins with surfaces is a major problem involved in protein microarrays. Understanding protein/surface interactions is key to improving the performance of protein microarrays, but current understanding of the behavior of proteins on surfaces is lacking. Prevailing theories on the subject, which suggest that proteins should be stabilized when tethered to surfaces, do not explain the experimentally observed fact that proteins are often denatured on surfaces. In an attempt to develop some predictive capabilities with respect to protein/surface interactions, it was asked in previous works if the stabilization/destabilization of proteins on surfaces could be correlated to secondary structure …


Best Practices For Dealing With Price Volatility In Utah Commercial Construction, Justin Earl Weidman Jun 2010

Best Practices For Dealing With Price Volatility In Utah Commercial Construction, Justin Earl Weidman

Theses and Dissertations

In the commercial construction industry, the problem of price volatility as it pertains to materials and labor is a consistent problem. The changing instability of market conditions presents a challenge for construction companies to accurately estimate and complete projects within budget. This volatility can lead to higher costs and more risk to suppliers, contractors, and owners which can cause financial distress for all parties involved in the construction process. As lump sum contracts are typically being used on many projects, the owners seem to have the upper hand and are forcing contractors to honor lump sum contracts even when prices …


Flammability Limits, Flash Points, And Their Consanguinity: Critical Analysis, Experimental Exploration, And Prediction, Jeffrey R. Rowley Jun 2010

Flammability Limits, Flash Points, And Their Consanguinity: Critical Analysis, Experimental Exploration, And Prediction, Jeffrey R. Rowley

Theses and Dissertations

Accurate flash point and flammability limit data are needed to design safe chemical processes. Unfortunately, improper data storage and reporting policies that disregard the temperature dependence of the flammability limit and the fundamental relationship between the flash point and the lower flammability limit have resulted in compilations filled with erroneous values. To establish a database of consistent flammability data, critical analysis of reported data, experimental investigation of the temperature dependence of the lower flammability limit, and theoretical and empirical exploration of the relationship between flash points and temperature limits are undertaken. Lower flammability limit measurements in a 12-L ASHRAE style …


Piezoresistive Nano-Composites: Characterization And Applications, Thomas B. Hyatt Jun 2010

Piezoresistive Nano-Composites: Characterization And Applications, Thomas B. Hyatt

Theses and Dissertations

Innovative multifunctional materials are essential to many new sensor applications. Piezoresistive nano-composites make up a promising class of such materials that have the potential to provide a measurable response to strain over a much wider range than typical strain gages. Commercial strain gages are currently dominated by metallic sensors with a useable range of a few percent strain at most. There are, however, many applications that would benefit from a reliable wide-range sensor. These might include the study of explosive behavior, instrumentation of flexible components, motion detection for compliant mechanisms and hinges, human-technology interfaces, and a wide variety of bio-mechanical …


Results And Analysis Of A Required Senior Exam To Assess Learning Of Course Competencies, Randy Lewis, Thomas Knotts, W Vincent Wilding, William Pitt, Morris Argyle Jun 2010

Results And Analysis Of A Required Senior Exam To Assess Learning Of Course Competencies, Randy Lewis, Thomas Knotts, W Vincent Wilding, William Pitt, Morris Argyle

Faculty Publications

As part of the ABET Accreditation Criterion, Program Outcomes refer to the outcomes that chemical engineering students should possess when they leave the university and enter the workforce. In 1999, as a response to ABET’s EC2000 criterion, a list of specific competencies was defined in the Chemical Engineering Program at Brigham Young University that, when taken together, constituted each Program Outcome. When the competencies were first developed, it became clear that the level of mastery expected from students varied from competency to competency. Exposure to the material was all that was required for some competencies. For others, it was our …


Results And Analysis Of A Required Senior Exam To Assess Learning Of Course Competencies, Randy Lewis, Thomas Knotts, W. Vincent Wilding, William G. Pitt, Morris D. Argyle Jun 2010

Results And Analysis Of A Required Senior Exam To Assess Learning Of Course Competencies, Randy Lewis, Thomas Knotts, W. Vincent Wilding, William G. Pitt, Morris D. Argyle

Faculty Publications

As part of the ABET Accreditation Criterion, Program Outcomes refer to the outcomes that chemical engineering students should possess when they leave the university and enter the workforce. In 1999, as a response to ABET’s EC2000 criterion, a list of specific competencies was defined in the Chemical Engineering Program at Brigham Young University that, when taken together, constituted each Program Outcome. When the competencies were first developed, it became clear that the level of mastery expected from students varied from competency to competency. Exposure to the material was all that was required for some competencies. For others, it was our …


Natural Fibers And Fiberglass: A Technical And Economic Comparison, Justin Andrew Zsiros Jun 2010

Natural Fibers And Fiberglass: A Technical And Economic Comparison, Justin Andrew Zsiros

Theses and Dissertations

Natural fibers have received attention in recent years because of their minimal environmental impact, reasonably good properties, and low cost. There is a wide variety of natural fibers suitable for composite applications, the most common of which is flax. Flax has advantages in tensile strength, light weight, and low cost over other natural fibers. As with other natural and synthetic fibers, flax is used to reinforce both thermoset and thermoplastic matrices. When flax is used in thermoplastic matrices, polypropylene and polyethylene are the main resins used. Although at first glance flax may seem to be a cheaper alternative to fiberglass, …


Numerical Analysis Of The Effectiveness Of Limited Width Gravel Backfills In Increasing Lateral Passive Resistance, Mo'oud Nasr Jun 2010

Numerical Analysis Of The Effectiveness Of Limited Width Gravel Backfills In Increasing Lateral Passive Resistance, Mo'oud Nasr

Theses and Dissertations

Two series of static full-scale lateral pile cap tests were conducted on pile caps with different aspect ratios, with full width (homogeneous) and limited width backfill conditions involving loose sand and dense gravel. The limited width backfills were constructed by placing a relatively narrow zone (3 to 6 ft (0.91 to 1.83 m)) of higher density gravel material adjacent to the cap with loose sand beyond the gravel zone. Test results indicated that large increases in lateral passive resistance could be expected for limited width backfills. The main focus of this study is to assess the contribution of plane strain …


Testing Guidelines For New Product Development, Derek W. Egbert Jun 2010

Testing Guidelines For New Product Development, Derek W. Egbert

Theses and Dissertations

While many literary sources outline the product development process, few make mention of the prototyping and testing stage. This thesis suggests that because of its importance in the product development process, "Testing" should be documented as a major step and not just listed as a side note. As part of the testing step, it is suggested that standardized, in-use, and market tests be used to properly evaluate a product. While many rely solely on standardized tests to validate their products, effective in-use tests can be another vital tool that can prove the performance of the product in more specific and …


Scatterometer Image Reconstruction Tuning And Aperture Function Estimation For Advanced Microwave Scanning Radiometer On The Earth Observing System, Brian Adam Gunn May 2010

Scatterometer Image Reconstruction Tuning And Aperture Function Estimation For Advanced Microwave Scanning Radiometer On The Earth Observing System, Brian Adam Gunn

Theses and Dissertations

AMSR-E is a space-borne radiometer which measures Earth microwave emissions or brightness temperatures (Tb) over a wide swath. AMSR-E data and images are useful in mapping valuable Earth-surface and atmospheric phenomena. A modified version of the Scatterometer Image Reconstruction (SIR) algorithm creates Tb images from the collected data. SIR is an iterative algorithm with tuning parameters to optimize the reconstruction for the instrument and channel. It requires an approximate aperture function for each channel to be effective. This thesis presents a simulator-based optimization of SIR iteration and aperture function threshold parameters for each AMSR-E channel. A comparison of actual Tb …


Optimization And Correlation Of The Penn State Model Of Friction Stir Welding To Experimental Welds In 304l Stainless Steel, Devin Donaldson Furse May 2010

Optimization And Correlation Of The Penn State Model Of Friction Stir Welding To Experimental Welds In 304l Stainless Steel, Devin Donaldson Furse

Theses and Dissertations

A numerical model of friction stir welding developed by T. DebRoy, R. Nandan, and others has been optimized to fit experimental data of eleven welds of 304L stainless steel at various weld feed rates and spindle speeds. Optimization was used to determine the values of five difficult-to-measure model parameters. The optimal parameter values were then correlated to the weld machine inputs. The mechanical efficiency and the coefficient of friction were not correlated with feed rate, spindle speed, or axial pressure. Tool slip was positively correlated with feed rate, negatively correlated with spindle speed, and not correlated with axial pressure. The …


High Temperature Water Gas Shift Catalysts With Alumina, Morris D. Argyle, Tiberiu Popa, Guoqing Xu, Thomas F. Barton May 2010

High Temperature Water Gas Shift Catalysts With Alumina, Morris D. Argyle, Tiberiu Popa, Guoqing Xu, Thomas F. Barton

Faculty Publications

Alumina (Al2O3) was added as a component of conventional iron oxide based high temperature water gas shift (WGS) catalysts. The catalysts contained Fe-Al-Cr-Cu-O and were synthesized by coprecipitation. A series of catalysts were prepared with 5 to 50 wt% Al2O3, 8 wt% Cr2O3, 4 wt% CuO, and the balance Fe2O3. One catalyst was prepared in which the chromia was replaced by alumina. All of the catalysts were compared to a reference WGS catalyst (88 wt% FeOX, 8 wt% Cr2O3, and 4 wt% CuO) with no alumina. The catalysts were characterized using temperature programmed reduction (TPR), surface area analysis using nitrogen …