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Theses and Dissertations

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Full-Text Articles in Engineering

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 …


The Extraction Of Cytochrome C And Dsred2 Into Reverse Micelles, Michelle Baker Sep 2009

The Extraction Of Cytochrome C And Dsred2 Into Reverse Micelles, Michelle Baker

Theses and Dissertations

Cytochrome c and DsRed2 were successfully extracted into reverse micelles by the contacting of an aqueous protein-containing phase with an organic phase. Two important properties that differentiate the extraction profiles of these proteins are pI and size. Cytochrome c is a relatively small, monomeric protein with a pI of 10.6. It was easily extracted into reverse micelles with the anionic surfactant AOT. DsRed2, however, is a large tetramer with a p1 of 6.3. It could not be extracted into AOT, but was extracted with the cationic surfactant CTAB, and with a wider error range than cytochrome c. CD data indicate …


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 …


Precision Navigation Using Pre-Georegistered Map Data, Frederick C. Webber Sep 2009

Precision Navigation Using Pre-Georegistered Map Data, Frederick C. Webber

Theses and Dissertations

Navigation performance in small unmanned aerial vehicles (UAVs) is adversely affected by limitations in current sensor technology for small, lightweight sensors. Because most UAVs are equipped with cameras for mission-related purposes, it is advantageous to utilize the camera to improve the navigation solution. This research improves navigation by matching camera images to a priori georegistered image data and combining this update with existing image-aided navigation technology. The georegistration matching is done by projecting the images into the same plane, extracting features using the techniques Scale Invariant Feature Transform (SIFT) [5] and Speeded-Up Robust Features (SURF) [3]. The features are matched …


Pulsed Film Cooling On A Turbine Blade Leading Edge, James L. Rutledge Sep 2009

Pulsed Film Cooling On A Turbine Blade Leading Edge, James L. Rutledge

Theses and Dissertations

Unsteadiness in gas turbine film cooling jets may arise due to inherent unsteadiness of the flow through an engine or may be induced as a means of flow control. The traditional technique used to evaluate the performance of a steady film cooling scheme is demonstrated to be insufficient for use with unsteady film cooling and is modified to account for the cross coupling of the time dependent adiabatic effectiveness and heat transfer coefficient. The addition of a single term to the traditional steady form of the net heat flux reduction equation with time averaged quantities accounts for the unsteady effects. …


F-16 Ventral Fin Buffet Alleviation Using Piezoelectric Actuators, Joseph S. Browning Sep 2009

F-16 Ventral Fin Buffet Alleviation Using Piezoelectric Actuators, Joseph S. Browning

Theses and Dissertations

Buffet-induced vibrations can have a disastrous impact on aircraft structures. Early attempts at combating buffet vibrations included passive methods such as structural enhancements and leading edge fences. Active methods have shown greater promise, including active airflow control, control surface modulation, and active structural control using piezoelectric actuators. Surface mounted piezoelectric actuators impart directional strain reducing the negative effects associated with harmful vibration. The Block-15 F-16 ventral fin represents an aircraft structure prone to failure when subjected to the buffet field from the wake of a LANTIRN pod. This research takes advantage of the susceptibility to buffet vibration of the Block …


Alternative Methods To Standby Gain Scheduling Following Air Data System Failure, Matthew W. Coldsnow Sep 2009

Alternative Methods To Standby Gain Scheduling Following Air Data System Failure, Matthew W. Coldsnow

Theses and Dissertations

The United States Air Force has advanced fighter aircraft that lose the ability to operate in a large portion of their operating flight envelope when an air data system failure is experienced. These aircraft are reverted to a fixed set of standby-gains that limit their maneuverability, degrade handling qualities, and increase susceptibility to departure. The purpose of this research was to determine if three alternative methods of standby-gain-scheduling could provide robust control with minimal performance degradation despite the lack of air data. To accomplish this, three methods of standby-gain-scheduling were developed, integrated, and tested in the Infinity Cube simulator at …


Thermo-Mechanical Characterization Of Silicon Carbide-Silicon Carbide Composites At Elevated Temperatures Using A Unique Combustion Facility, Ted T. Kim Sep 2009

Thermo-Mechanical Characterization Of Silicon Carbide-Silicon Carbide Composites At Elevated Temperatures Using A Unique Combustion Facility, Ted T. Kim

Theses and Dissertations

This research investigated four different types of CMCs in a simulated gas turbine engine hot section condition that involved the simultaneous application of a combustion environment and mechanical fatigue loading using a unique burner rig facility developed for this study at AFIT. Three of the materials were woven Melt-Infiltrated (MI) BN/SiC reinforced by Hi-Nicalon Type S (Hi-Nic-S), Sylramic (Syl) and Sylramic with insitu BN coating (Syl-iBN) fibers, respectively. They were made by the slurry cast method. The other CMC was MI Hi-Nic-S/BN/SiC made using the prepreg MI processing. Prepreg MI CMC and Sylramic-iBN fiber reinforced CMC showed better resistance to …


Least-Squares, Continuous Sensitivity Analysis For Nonlinear Fluid-Structure Interaction, Douglas P. Wickert Sep 2009

Least-Squares, Continuous Sensitivity Analysis For Nonlinear Fluid-Structure Interaction, Douglas P. Wickert

Theses and Dissertations

A least-squares, continuous sensitivity analysis method is developed for transient aeroelastic gust response problems to support computationally efficient analysis and optimization of aeroelastic design problems. A key distinction between the local and total derivative forms of the sensitivity system is introduced. The continuous sensitivity equations and sensitivity boundary conditions are derived in local derivative form which is shown to be superior for several applications. The analysis and sensitivity problems are both posed in a first-order form which is amenable to a solution using the least-squares finite element method. Several example and validation problems are presented and solved, including elasticity, fluid, …


Electronic Image Stabilization For Mobile Robotic Vision Systems, Michael John Smith Sep 2009

Electronic Image Stabilization For Mobile Robotic Vision Systems, Michael John Smith

Theses and Dissertations

When a camera is affixed on a dynamic mobile robot, image stabilization is the first step towards more complex analysis on the video feed. This thesis presents a novel electronic image stabilization (EIS) algorithm for small inexpensive highly dynamic mobile robotic platforms with onboard camera systems. The algorithm combines optical flow motion parameter estimation with angular rate data provided by a strapdown inertial measurement unit (IMU). A discrete Kalman filter in feedforward configuration is used for optimal fusion of the two data sources. Performance evaluations are conducted by a simulated video truth model (capturing the effects of image translation, rotation, …


The Navigation Potential Of Ground Feature Tracking, Guner Mutlu Sep 2009

The Navigation Potential Of Ground Feature Tracking, Guner Mutlu

Theses and Dissertations

This research effort examines the reduction of error in inertial navigation aided by vision. This is part of an effort focused on navigation in a GPS denied environment. The navigation concept examined here consists of two main steps. First, extract the position of a tracked ground object using vision and geo-locate it in 3 dimensional navigation frame. In this first step multiple positions of the UAV are assumed known; think of a synthetic aperture. The only information about the tracked ground objects/features is the unit vector that points to the objects from the center of the camera. Two such vectors …


Synthesis, Interdiction, And Protection Of Layered Networks, Kevin T. Kennedy Sep 2009

Synthesis, Interdiction, And Protection Of Layered Networks, Kevin T. Kennedy

Theses and Dissertations

This research developed the foundation, theory, and framework for a set of analysis techniques to assist decision makers in analyzing questions regarding the synthesis, interdiction, and protection of infrastructure networks. This includes extension of traditional network interdiction to directly model nodal interdiction; new techniques to identify potential targets in social networks based on extensions of shortest path network interdiction; extension of traditional network interdiction to include layered network formulations; and develops models/techniques to design robust layered networks while considering trade-offs with cost. These approaches identify the maximum protection/disruption possible across layered networks with limited resources, find the most robust layered …


Changes In Structural Health Monitoring System Capability Due To Aircraft Environmental Factors, Jeffrey D. Kuhn Sep 2009

Changes In Structural Health Monitoring System Capability Due To Aircraft Environmental Factors, Jeffrey D. Kuhn

Theses and Dissertations

Structural Health Monitoring (SHM) promises to decrease the maintenance cost and increase the availability of aging aircraft fleets by fundamentally changing the way structural inspections are performed. But this promise can only be realized through the consistent and predictable performance of a SHM system throughout the entire remaining life of an aircraft. In a sensor-based SHM system, sensor signal changes are analyzed and interpreted to identify structural flaws. But aircraft environmental factors such as temperature fluctuations, cyclic strain and exposure to various aircraft fluids also have the potential to change SHM sensor signals, raising questions about long term SHM system …


Analysis And Modeling Of Motor Vehicle Crashes Involving Air Force Military Personnel, Antonios Markopoulos Sep 2009

Analysis And Modeling Of Motor Vehicle Crashes Involving Air Force Military Personnel, Antonios Markopoulos

Theses and Dissertations

The primary purpose of this thesis was to improve the data analysis of Motor Vehicle Crashes (MVCs). This thesis employed the Air Force Safety Center (AFSC) data, collected over 20 years, of MVCs in which US Air Force (USAF) military personnel are involved when off duty and off base. Categorical Data Analysis and Analysis of Variance (ANOVA) were applied to identify risk factors related to MVCs and influence the severity of injuries and those factors associated with the alcohol consumption before driving, and affect the number of lost workdays resulting from MVCs. Categorical Data Analysis showed that male USAF members …


Formation Flight Of Earth Satellites On Kam Tori, Christopher T. Craft Aug 2009

Formation Flight Of Earth Satellites On Kam Tori, Christopher T. Craft

Theses and Dissertations

Kolmogorov, Arnold and Moser (KAM) theory provides that orbits of satellites whose dynamics are representable by an integrable Hamiltonian plus a small, real perturbation lie on tori in phase space and remain on the KAM tori for all time, unless acted upon by a non-conservative force. A refined technique for constructing KAM tori for Earth-orbiting satellites is developed and implemented using numerically integrated orbital data for hypothetical satellites and involving methods of Fourier analysis and spectral decomposition. Definition of satellite formations on the KAM tori is performed and analyses conducted to investigate both constellations with large separations and clusters with …


Design And Optimization Of Peristaltic Micropumps Using Evolutionary Algorithms, Ravi Bhadauria Aug 2009

Design And Optimization Of Peristaltic Micropumps Using Evolutionary Algorithms, Ravi Bhadauria

Theses and Dissertations

A design optimization based on coupled solid–fluid analysis is investigated in this work to achieve specific flow rate through a peristaltic micropump. A micropump consisting of four pneumatically actuated nozzle/diffuser shaped moving actuators on the sidewalls is considered for numerical study. These actuators are used to create pressure difference in the four pump chambers, which in turn drives the fluid through the pump in one direction. Genetic algorithms along with artificial neural networks are used for optimizing the pump geometry and the actuation frequency. A simple example with moving walls is considered for validation by developing an exact analytical solution …


Preparation And Characterization Of An Electrospun Gelatin/Dendrimer Hybrid Nanofiber Dressing, Alicia P. Smith-Freshwater Aug 2009

Preparation And Characterization Of An Electrospun Gelatin/Dendrimer Hybrid Nanofiber Dressing, Alicia P. Smith-Freshwater

Theses and Dissertations

A novel dendritic wound dressing was designed and characterized for its potential to treat chronic wounds. Comprised of gelatin, dendrimer, synthetic polymer and antibiotics, the dressing was electrospun to mimic the natural extracellular matrix (ECM). Gelatin is biocompatible, biodegradable, non-toxic, and easily available. The antibiotic, doxycycline, has the ability to inhibit matrix metalloproteinases. Matrix metalloproteinases, which occur in excess in chronic wounds, degrade the reconstituted ECM. Starburst™ polyamidoamine (PAMAM) dendrimer G3.5, which provides a versatile and structurally controlled architecture to construct nanomedicine, was covalently bonded to the gelatin backbone and electrospun into nanofibers with gelatin, doxycycline and stabilizing polymers. The …


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 …


Controlled Release Of Fluoride From Poly(Ethylene-Co-Vinyl Acetate) Films, Shadeed Khan Aug 2009

Controlled Release Of Fluoride From Poly(Ethylene-Co-Vinyl Acetate) Films, Shadeed Khan

Theses and Dissertations

The development of aesthetically unattractive white spots is a concern for patients undergoing fixed orthodontic treatment. Due to poor oral hygiene during treatment, accumulation of plaque around orthodontic brackets causes bacterial fermentation reactions producing acids that dissolve the mineral enamel. Such dissolution results in white spot formation, an early sign of dental caries. In principal, to inhibit the appearance of these spots during treatment, fluoridated elastomeric o-rings might be employed. Once placed around brackets, these o-rings should release fluoride therapeutically for at least 30 days, after which the orthodontist may replace them. At the present time, such fluoride-releasing o-rings are …


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. …


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 …


Functional Near-Infrared Spectroscopy For Hb And Hbo₂ Detection Using Remote Sensing, Rane M. Pierson Aug 2009

Functional Near-Infrared Spectroscopy For Hb And Hbo₂ Detection Using Remote Sensing, Rane M. Pierson

Theses and Dissertations

The goal of the work presented in this thesis is to develop a wireless, near-infrared (NIR) imaging system to provide flexibility and functionality to clinicians and researchers who require monitoring of blood profusion to tissue, muscles, or the brain. The prototype device uses a single stimulus/detection unit composed of an Epitex NIR LED with three wavelength options: 730, 805, and 850 nm, and an OPT101 photodiode detector. The device can be used to detect changes in the levels of oxygenated and deoxygenated hemoglobin in the body by measuring the amounts of absorbed and backscattered light at the wavelength associated with …


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.


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) …


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, …


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 …


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 …


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 …


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 …


The Use Of A Tri-Axial Accelerometer To Measure Changes In Lower Extremity Fatigue During Functional Activity, Kristin Morgan Aug 2009

The Use Of A Tri-Axial Accelerometer To Measure Changes In Lower Extremity Fatigue During Functional Activity, Kristin Morgan

Theses and Dissertations

In 2004, the National Collegiate Athletic Association reported ankle sprain as the most frequent injury in soccer, basketball, and volleyball players. Further research found an increased likelihood with fatigue. Measuring fatigue during functional activities has been a longstanding problem. In this study, changes in ankle biomechanics were measured using a tri-axial accelerometer embedded in the shoe as subjects (n=12) performed a fatiguing activity. Data were collected from the accelerometer and from established devices that are considered the industry gold standard. Several kinetic and kinematic accelerometer derived variables were highly correlated with these standards (r2>0.90) and were associated with changes …