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Articles 2761 - 2790 of 3926

Full-Text Articles in Engineering

In-Plane, All-Photonic Transduction Method For Silicon Photonic Microcantilever Array Sensors, Jong Wook Noh Nov 2009

In-Plane, All-Photonic Transduction Method For Silicon Photonic Microcantilever Array Sensors, Jong Wook Noh

Theses and Dissertations

We have invented an in-plane all-photonic transduction method for photonic microcantilever arrays that is scalable to large arrays for sensing applications in both bio- and nanotechnology. Our photonic transduction method utilizes a microcantilever forming a single mode rib waveguide and a differential splitter consisting of an asymmetric multimode waveguide and a Y-branch waveguide splitter. The differential splitter's outputs are used to form a differential signal that has a monotonic response to microcantilever deflection. A differential splitter using an amorphous silicon strip-loaded multimode rib waveguide is designed and fabricated to demonstrate the feasibility of the in-plane photonic transduction method. Our initial …

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Variability In Construction Of Cement-Treated Base Layers: Probabilistic Analysis Of Pavement Life Using Mechanistic-Empirical Approach, Tyler J. Rogers Nov 2009

Variability In Construction Of Cement-Treated Base Layers: Probabilistic Analysis Of Pavement Life Using Mechanistic-Empirical Approach, Tyler J. Rogers

Theses and Dissertations

The primary objective of this research was to quantify the improvement in service life of a flexible pavement constructed using full-depth reclamation (FDR) in conjunction with cement stabilization when specified reductions in the spatial variability of specific construction-related parameters are achieved. This study analyzed pavement data obtained through field and laboratory testing of a reconstruction project in northern Utah. Data analyses included multivariate regression, Monte Carlo simulation, and mechanistic-empirical analyses of a model pavement structure. The results of the research show a steadily increasing trend in 28-day unconfined compressive strength of the cement-treated base (CTB) layer with increasing reductions in …

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Automated Calibration Of The Gssha Watershed Model: A Look At Accuracy And Viability For Routine Hydrologic Modeling, Kayson M. Shurtz Nov 2009

Automated Calibration Of The Gssha Watershed Model: A Look At Accuracy And Viability For Routine Hydrologic Modeling, Kayson M. Shurtz

Theses and Dissertations

The goal of hydrologic models is to accurately predict a future event of a given magnitude. Historic data are often used to calibrate models to increase their ability to forecast accurately. The GSSHA model is a distributed model that uses physical parameters and physics based computations to compute water flow from cell to cell based on a 2 dimensional grid. The goal of calibration is to obtain good estimates for the actual parameters of the watershed. These parameters should then transfer to other storm events of different magnitudes more easily than an empirical model. In conducting this research three watersheds …

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An Evaluation Of Quikscat Uhr Wind Product's Effectiveness In Determining Selected Tropical Cyclone Characteristics, Faozi Said Nov 2009

An Evaluation Of Quikscat Uhr Wind Product's Effectiveness In Determining Selected Tropical Cyclone Characteristics, Faozi Said

Theses and Dissertations

While the standard wind product (L2B) available operationally in near-real time from SeaWinds on QuikSCAT is only 25 km in resolution, QuikSCAT data can be enhanced to yield a 2.5 km ultra-high resolution (UHR) product. The latter can be used to help estimate Tropical Cyclone (TC) characteristics such as TC eye center and wind radii. Two studies are conducted in this thesis, in which QuikSCAT UHR wind product's effectiveness in estimating these TC characteristics is evaluated. First, a comparison is made between the analyst's choice of eye location based on UHR images and interpolated best-track position. In this analysis, the …

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Slab-Coupled Optical Fiber Sensors For Electric Field Sensing Applications, Richard S. Gibson Nov 2009

Slab-Coupled Optical Fiber Sensors For Electric Field Sensing Applications, Richard S. Gibson

Theses and Dissertations

This dissertation presents the creation of slab coupled optical sensors (SCOS) for electric field sensing applications. SCOS devices utilize the benefits of an optical fiber system for high bandwidth and low electromagnetic interference. These sensors are fabricated by means of mode coupling between a small section of D-shaped optical fiber (D-fiber) with a multi-mode electro-optic slab waveguide. Electric field detection is accomplished by monitoring the behavior of the resonances, seen as transmission dips in the D-fiber transmission, as they shift with electric fields. The novelties of SCOS devices include their small compact nature, potential for sensor multiplexing and a dielectric …

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Improving Accuracy In Microwave Radiometry Via Probability And Inverse Problem Theory, Derek Lavell Hudson Nov 2009

Improving Accuracy In Microwave Radiometry Via Probability And Inverse Problem Theory, Derek Lavell Hudson

Theses and Dissertations

Three problems at the forefront of microwave radiometry are solved using probability theory and inverse problem formulations which are heavily based in probability theory. Probability theory is able to capture information about random phenomena, while inverse problem theory processes that information. The use of these theories results in more accurate estimates and assessments of estimate error than is possible with previous, non-probabilistic approaches. The benefits of probabilistic approaches are expounded and demonstrated. The first problem to be solved is a derivation of the error that remains after using a method which corrects radiometric measurements for polarization rotation. Yueh [1] proposed …

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Investigate Correlations Of Microstructures, Mechanical Properties And Fsw Process Variables In Friction Stir Welded High Strength Low Alloy 65 Steel, Lingyun Wei Nov 2009

Investigate Correlations Of Microstructures, Mechanical Properties And Fsw Process Variables In Friction Stir Welded High Strength Low Alloy 65 Steel, Lingyun Wei

Theses and Dissertations

The present study focuses on developing a relationship between process variables, mechanical properties and post weld microstructure in Friction Stir Welded HSLA 65 steel. Fully consolidated welds can be produced in HSLA 65 steel by PCBN Convex-Scrolled-Shoulder-Step-Spiral (CS4) tool over a wide range of parameters. Microstructures in the nugget center (NC) are dominated by lath bainite and a few polygonal/allotriomorphic grain boundary ferrites. FSW dependent variables are related to FSW independent variables by non-linear relationship. Heat input is identified to be the best parameter index to correlate with microstructures. With increasing heat input, the volume of bainite is reduced, the …

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Optimizing The Release And Methylation Of Bacterial Endospore Dipicolinic Acid, Aaron N. Nackos Nov 2009

Optimizing The Release And Methylation Of Bacterial Endospore Dipicolinic Acid, Aaron N. Nackos

Theses and Dissertations

Rapid, portable detection of biological threat agents such as Bacillus anthracis endospores (“spores”) is extremely important given the real and perceived threats of bioterrorism. Gas chromatography-mass spectrometry (GC-MS) is an excellent general means for chemical detection, although special sample preparation and specialized equipment are required to employ GC-MS for detecting biological agents such as spores in the field. A GC sample introduction probe consisting of a helical wire that can be retracted inside a syringe needle, called a coiled wire filament (CWF), was employed as a simple, passively-heated means to introduce the mixture of spores plus reagents for thermochemolysis methylation …

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In-Plane All-Photonic Transduction With Differential Splitter Using Double-Step Rib Waveguide For Photonic Microcantilever Arrays, Ryan Anderson, Seunghyun Kim, Gregory P. Nordin, Jong Wook Noh, Weisheng Hu Oct 2009

In-Plane All-Photonic Transduction With Differential Splitter Using Double-Step Rib Waveguide For Photonic Microcantilever Arrays, Ryan Anderson, Seunghyun Kim, Gregory P. Nordin, Jong Wook Noh, Weisheng Hu

Faculty Publications

We report a differential splitter consisting of an asymmetric double-step multimode rib waveguide and a Y-branch splitter for in-plane photonic transduction of photonic microcantilever deflection. Arrays of photonic microcantilevers are integrated with differential splitters and an optical waveguide network to demonstrate uniformity and sensitivity of transduction. Measurement results from multiple arrays indicate a sensitivity of 0.32 x 10-3 nm-1 and minimum detectable deflection of 141 pm for a 3.5 Hz measurement bandwidth.

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Research In Information Technology: Analysis Of Existing Graduate Research, Christopher John Cole Oct 2009

Research In Information Technology: Analysis Of Existing Graduate Research, Christopher John Cole

Theses and Dissertations

Information Technology is an academic discipline that is well recognized by the academic community. There is an increasing number of schools offering degrees in Information Technology and has there is an official curriculum published with the ACM/IEEE computing Curriculum. A concern with Information Technology as an academic discipline is that it does not have a clearly defined set of research issues which are not studied by any other discipline. One way to propose this set of issues is to perform a “bottom-up” analysis and gather research in IT that has already been published. This research can then be analyzed for …

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Automated Data Import And Revision Management In A Product Lifecycle Management Environment, Brad Walton Brooks Oct 2009

Automated Data Import And Revision Management In A Product Lifecycle Management Environment, Brad Walton Brooks

Theses and Dissertations

A method has been created that addresses the issues that prohibit the conversion of product artifacts into a secure, efficient and reliable Product Lifecycle Management (PLM) environment. These issues include automatic import of data into a PLM system and revision control of such data. A test case is shown which specifically addresses these issues as they pertain to the management of both legacy and new engineering data in a PLM system.

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Low Cost/ High Precision Flight Dynamics Estimation Using The Square-Root Unscented Kalman Filter, Trevor H. Paulsen Oct 2009

Low Cost/ High Precision Flight Dynamics Estimation Using The Square-Root Unscented Kalman Filter, Trevor H. Paulsen

Theses and Dissertations

For over a decade, Brigham Young University's Microwave Earth Remote Sensing (MERS) team has been developing SAR systems and SAR processing algorithms. In order to create the most accurate image reconstruction algorithms, detailed aircraft motion data is essential. In 2008, the MERS team purchased a costly inertial measurement unit (IMU) coupled with a high precision global positioning system (GPS) from NovAtel, Inc. In order to lower the cost of obtaining detailed motion measurements, the MERS group decided to build a system that mimics the capability the NovAtel system as closely as possible for a much lower cost. As a first …

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Haptic Collision Avoidance For A Remotely Operated Quadrotor Uav In Indoor Environments, Adam M. Brandt Sep 2009

Haptic Collision Avoidance For A Remotely Operated Quadrotor Uav In Indoor Environments, Adam M. Brandt

Theses and Dissertations

A quadrotor is an omnidirectional unmanned air vehicle that is suitable for indoor flight because of its ability to hover and maneuver in confined spaces. The remote operation of this type of vehicle is difficult due to a lack of sensory perception; typically, the view from the onboard camera is the only information transmitted to the pilot. This thesis proposes using force feedback exerted by the command input device on the hand of the pilot to assist in avoiding collisions while navigating in indoor environments. Five candidate algorithms are presented for calculating the forces to be felt by the pilot …

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New Low-Complexity Equalizers For Offset Qpsk, Qiang Lei, Michael D. Rice Sep 2009

New Low-Complexity Equalizers For Offset Qpsk, Qiang Lei, Michael D. Rice

Faculty Publications

Reduced-complexity linear and decision-feedback equalizers for use with offset QPSK are described and analyzed. The analysis and simulations show that reduced-complexity equalizers have 1/4 the complexity and achieve this at a loss that depends on the channel. As an example, the loss for the “Proakis B” channel is 2.7 dB for the linear equalizer and 0.8 dB for the decision feedback equalizer.

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Performance Flight Testing Of Small Electric Powered Unmanned Aerial Vehicles, Jon N. Ostler, W. Jerry Bowman, Deryl O. Snyder, Timothy W. Mclain Sep 2009

Performance Flight Testing Of Small Electric Powered Unmanned Aerial Vehicles, Jon N. Ostler, W. Jerry Bowman, Deryl O. Snyder, Timothy W. Mclain

Faculty Publications

Flight testing methods are developed to find the drag polar for small unmanned aerial vehicles powered by electric motors with fixed-pitch propellers. Wind tunnel testing was used to characterize the propeller-motor efficiency. The drag polar was constructed using data from flight tests. This drag polar was then used to find the following performance parameters: maximum velocity, minimum velocity, velocity for maximum range, velocity for maximum endurance, maximum rate of climb, maximum climb angle, minimum turn radius, maximum turn rate, and maximum bank angle. The developed flight testing methods are used to characterize the performance of a small UAV.

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Numerical Characterizaton Of The Inlet Flow In Eleven Radial Flow Turbomachines, Nathan O. Packard Aug 2009

Numerical Characterizaton Of The Inlet Flow In Eleven Radial Flow Turbomachines, Nathan O. Packard

Theses and Dissertations

Statistics based models have been developed previously to predict a priori the performance of new radial flow compressors and pumps and to model test data of previously designed and tested machines. Unfortunately, critical dynamics in the inlet region of the machines were neglected. Consequently, room for improvement in the previous modeling exists. Historical practice has placed a static pressure tap on the shroud just upstream of the impeller leading edge for experimental characterization. The previously developed statistics based models rely on this measured data. However, the location of the tap may be vulnerable to high gradients which would decrease the …

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Experimental Characterization Of Flow Induced Vibration In Turbulent Pipe Flow, Andrew S. Thompson Aug 2009

Experimental Characterization Of Flow Induced Vibration In Turbulent Pipe Flow, Andrew S. Thompson

Theses and Dissertations

This thesis presents results of an experimental investigation that characterizes the wall vibration of a pipe with turbulent flow passing through it. Specifically, experiments were conducted using a water flow loop to address three general phenomena. The topics of investigation were: 1) How does the pipe wall vibration depend on the average flow speed, pipe diameter, and pipe thickness for an unsupported pipe? 2) How does the behavior change if the pipe is clamp supported at various clamping lengths? 3) What influence does turbulence generation caused by holed baffle plates exert on the pipe response? A single pipe material (PVC) …

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Piezoresistive Models For Polysilicon With Bending Or Torsional Loads, Gerrit T. Larsen Aug 2009

Piezoresistive Models For Polysilicon With Bending Or Torsional Loads, Gerrit T. Larsen

Theses and Dissertations

This thesis presents new models for determining piezoresistive response in long, thin polysilicon beams with either axial and bending moment inducing loads or torsional loads. Microelectromechanical (MEMS) test devices and calibration methods for finding the piezoresistive coefficients are also presented for both loading conditions. For axial and bending moment inducing loads, if the piezoresistive coefficients are known, the Improved Piezoresistive Flexure Model (IPFM) is used to find the new resistance of a beam under stress. The IPFM first discretizes the beam into small volumes represented by resistors. The stress that each of these volumes experiences is calculated, and the stress …

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Analysis Of Induced Vibrations In Fully-Developed Turbulent Pipe Flow Using A Coupled Les And Fea Approach, Thomas P. Shurtz Aug 2009

Analysis Of Induced Vibrations In Fully-Developed Turbulent Pipe Flow Using A Coupled Les And Fea Approach, Thomas P. Shurtz

Theses and Dissertations

Turbulent flow induced pipe vibration is a phenomenon that has been observed but not fully characterized. This thesis presents research involving numerical simulations that have been used to characterize pipe vibration resulting from fully developed turbulent flow. The vibration levels as indicated by: pipe surface displacement, velocity, and acceleration are characterized in terms of the parameters that exert influence. The influences of geometric and material properties of the pipe are investigated for pipe thickness in the range 1 to 8 mm at a diameter of 0.1015 m. The effects of pipe elastic modulus are explored from 3 to 200 GPa. …

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Isogeometric Finite Element Analysis Using T-Splines, Jingang Li Aug 2009

Isogeometric Finite Element Analysis Using T-Splines, Jingang Li

Theses and Dissertations

Non-uniform rational B-splines (NURBS) methodology is presented, on which the isogeometric analysis is based. T-splines are also introduced as a surface design methodology, which are a generalization of NURBS and permit local refinement. Isogeometric analysis using NURBS and T-splines are applied separately to a structural mechanics problem. The results are compared with the closed-form solution. The desirable performance of isogeometric analysis using T-splines on engineering analysis is demonstrated.

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A System Level Approach To D-Fiber Electric Field Sensing, Joshua Monroe Kvavle Aug 2009

A System Level Approach To D-Fiber Electric Field Sensing, Joshua Monroe Kvavle

Theses and Dissertations

This dissertation presents the novel creation of a hybrid D-fiber electro-optic polymer electric field sensor. The sensor is made by removing a portion of the cladding from a D-shaped optical fiber, thus exposing the core to interaction with external stimulus. Then, an electro-optic polymer is deposited, partially replacing the core of the fiber. Next, the polymer is poled to endow it with electro-optic properties. This sensor is packaged in order to restore its mechanical strength. Because D-fiber is not intrinsically compatible with standard optical equipment it is fusion spliced to standard polarization maintaining fiber. Finally the sensor is tested for …

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Deposition Of Particulate From Coal-Derived Syngas On Gas Turbine Blades Near Film Cooling Holes, Weiguo Ai Aug 2009

Deposition Of Particulate From Coal-Derived Syngas On Gas Turbine Blades Near Film Cooling Holes, Weiguo Ai

Theses and Dissertations

Synfuel from gasification of coal, biomass, and/or petroleum coke is an alternative to natural gas in land-based industrial gas turbines. However, carryover fine particulate in the syngas may lead to a considerable amount of deposition on turbine blades, which reduces component life and system performance. Deposition experiments on film-cooled turbine components were performed in an accelerated test facility to examine the nature of flyash deposits near film cooling holes. Experimental results indicate that deposition capture efficiency decreased with increased blowing ratio. Shaped holes exhibited more span-wise coverage than cylindrical holes and effectively reduced deposition. The TBC layer increased surface temperature, …

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Off-Axis Stiffness And Piezroresistive Sensing In Large-Displacement Linear-Motion Microelectromechanical Systems, David G. Smith Aug 2009

Off-Axis Stiffness And Piezroresistive Sensing In Large-Displacement Linear-Motion Microelectromechanical Systems, David G. Smith

Theses and Dissertations

Proper positioning of Microelectromechanical Systems (MEMS) components influences the functionality of the device, especially in devices where the motion is in the range of hundreds of micrometers. There are two main obstacles to positioning: off-axis displacement, and position determination. This work studies four large-displacement devices, their axial and transverse stiffness, and piezoresistive response. Methods for improving the device characteristics are described. The folded-beam suspension, small X-Bob, large X-Bob and double X-Bob were characterized using non-dimensional metrics that measure the displacement with regard to the size of the device, and transverse stiffness with regard to axial stiffness. The stiffness in each …

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Analysis Of The Sediment Transport Capabilities Of Tuflow, Cameron G. Jenkins Aug 2009

Analysis Of The Sediment Transport Capabilities Of Tuflow, Cameron G. Jenkins

Theses and Dissertations

The need to know how river morphology changes due to sedimentation is increasingly important as we attempt to predict future events. Engineers use numeric models to predict effects of changed morphology on river systems. The numerical model Two-dimensional Unsteady Flow (TUFLOW) has recently added, and is continually improving, its capability to model sediment transport in rivers and coastal systems. This paper evaluates the new tools for modeling sediment transport presently contained within TUFLOW and compares these tools with analytical and laboratory case studies. Currently TUFLOW simulates combined bed and suspended load transport of noncohesive sediments under the effect of currents …

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Liquefaction Mitigation In Silty Sands Using Stone Columns With Wick Drains, Michael James Quimby Aug 2009

Liquefaction Mitigation In Silty Sands Using Stone Columns With Wick Drains, Michael James Quimby

Theses and Dissertations

Stone column treatment is commonly used to mitigate liquefaction hazard in sandy soils. Research and experience indicate that this method is effective for clean sands but that it may not be effective for silts and sands with fines contents greater than 15-20%. An alternative to the stone column method involves supplementing stone column treatment with pre-fabricated vertical wick drains installed prior to the stone columns installation. Although this method is used in practice, there has not been a formal academic study of its effectiveness. This thesis evaluates seven different case histories where wick drains were used and one where wick …

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Active Human Power Generation: As A New Portion Of The Energy Supply, Robert J. Mccleary Ii Aug 2009

Active Human Power Generation: As A New Portion Of The Energy Supply, Robert J. Mccleary Ii

Library Research Grants

The discovery and use of energy has revolutionized society for more then two hundred years. With it we have witnessed an explosion of knowledge and technology unparallel in history. Unfortunately our main sources of energy are in limited supply. In order to continue to enjoy the progress made during these last few centuries it is necessary to know both when our supply will run out and to find alternative sources.

The question of when the fossil fuels will run out has been on the minds of many scientists for more than fifty years. In 1956 Dr. M. King Hubbert developed …

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A Methodology For Designing Product Components With Built-In Barriers To Reverse Engineering, Stephen P. Harston Jul 2009

A Methodology For Designing Product Components With Built-In Barriers To Reverse Engineering, Stephen P. Harston

Theses and Dissertations

Reverse engineering, defined as extracting information about a product from the product itself, is a common industry practice for gaining insight into innovative products. Both the original designer and those reverse engineering the original design can benefit from estimating the time and barrier to reverse engineer a product. This thesis presents a set of metrics and parameters that can be used to calculate the barrier to reverse engineer any product as well as the time required to do so. To the original designer, these numerical representations of the barrier and time can be used to strategically identify and improve product …

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Radiation And Convection Heat Transfer In Wildland Fire Environments, David J. Frankman Jul 2009

Radiation And Convection Heat Transfer In Wildland Fire Environments, David J. Frankman

Theses and Dissertations

Wildland fire research has been extensive and on going since before 1950. The motivation behind this research is to prevent loss of property and lives. In spite of this research, the heat transfer of fuel ignition and flame spread is not well understood. This dissertation seeks to fill gaps in this understanding through modeling and also by experimentation. The effect of water vapor on the transmission of thermal radiation from the flame to the fuel was investigated. The Spectral Line Weighted-sum-of-gray-gases approach was adopted for treating the spectral nature of the radiation. The study reveals that water vapor has only …

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A Method For Making In Situ Emittance Measurements Of Coal Ash Deposits, Travis J. Moore Jul 2009

A Method For Making In Situ Emittance Measurements Of Coal Ash Deposits, Travis J. Moore

Theses and Dissertations

A major problem associated with any power generation process in which coal is burned is the formation of ash and slag from the inorganic constituents of the coal. Ash deposition on heat transfer surfaces in coal-fired reactors is unavoidable and can have a significant effect on the performance and maintenance of boilers and gasifiers. A greater understanding of the thermal properties of coal ash deposits is important in reducing their negative impact. This work presents the development of an experimental method for making in situ measurements of the spectral emittance of coal ash deposits. It also provides measured emittances for …

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Characterizing Material Property Tradeoffs Of Polycrystalline Diamond For Design Evaluation And Selection, Neil David Haddock Jul 2009

Characterizing Material Property Tradeoffs Of Polycrystalline Diamond For Design Evaluation And Selection, Neil David Haddock

Theses and Dissertations

Polycrystalline diamond (PCD) is used as a cutting tool in many industries because of its superior wear resistance compared to single crystal diamond. Engineers who design new PCD materials must have an understanding of the tradeoffs between material properties in order to tailor a product for different applications. Two competing material properties that are often encountered in PCD are transverse rupture strength and thermal-resistance. Thermal-resistance is directly related to the cobalt content of PCD, and is the ability of the material to withstand thermally induced degradation. In this thesis, we characterize the tradeoff boundary between transverse rupture strength and cobalt …

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