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Full-Text Articles in Mechanical Engineering

Takeoff And Performance Tradeoffs Of Retrofit Distributed Electric Propulsion For Urban Transport, Kevin Moore, Andrew Ning Aug 2019

Takeoff And Performance Tradeoffs Of Retrofit Distributed Electric Propulsion For Urban Transport, Kevin Moore, Andrew Ning

Faculty Publications

While vertical takeoff and landing aircraft have shown promise for urban air transport, distributed electric propulsion on existing aircraft may offer immediately implementable alternatives. Distributed electric propulsion could potentially decrease takeoff distances enough to enable thousands of potential inter-city runways. This conceptual study explores the effects of a retrofit of open-bladed electric propulsion units. To model and explore the design space we use blade element momentum method, vortex lattice method, linear-beam finite element analysis, classical laminate theory, composite failure, empirically-based blade noise modeling, motor and motor-controller mass models, and gradient-based optimization. With liftoff time of seconds and the safe total ...


Optimization Of Turbine Design In Wind Farms With Multiple Hub Heights, Using Exact Analytic Gradients And Structural Constraints, Andrew P.J. Stanley, Andrew Ning, Katherine Dykes Jan 2019

Optimization Of Turbine Design In Wind Farms With Multiple Hub Heights, Using Exact Analytic Gradients And Structural Constraints, Andrew P.J. Stanley, Andrew Ning, Katherine Dykes

Faculty Publications

Wind farms are generally designed with turbines of all the same hub height. If wind farms were designed with turbines of different hub heights, wake interference between turbines could be reduced, lowering the cost of energy (COE). This paper demonstrates a method to optimize onshore wind farms with two different hub heights using exact, analytic gradients. Gradient-based optimization with exact gradients scales well with large problems and is preferable in this application over gradient-free methods. Our model consisted of the following: a version of the FLOw Redirection and Induction in Steady-State wake model that accommodated three- dimensional wakes and calculated ...


Toward Building Resilient, Sustainable, And Smart Infrastructure In The 21st Century, Aly Mousaad Aly Nov 2018

Toward Building Resilient, Sustainable, And Smart Infrastructure In The 21st Century, Aly Mousaad Aly

Faculty Publications

In recent years, as a result of significant climate change, stringent windstorms are becoming more frequent than before. Given the threat that windstorms bring to people and property, wind/structural engineering research is imperative to improve the resilience of existing and new infrastructure, for community safety and assets protection. The Windstorm Impact, Science and Engineering (WISE) research program at Louisiana State University (LSU) focuses on creating new knowledge applicable to the mitigation of existing and new infrastructure, to survive and perform optimally under natural hazards. To achieve our research goals, we address two imperious challenges: (i) characterization of realistic wind ...


Visual Servoing For Multirotor Precision Landing In Varying Light Conditions, Jesse Wynn, Tim Mclain Aug 2018

Visual Servoing For Multirotor Precision Landing In Varying Light Conditions, Jesse Wynn, Tim Mclain

Faculty Publications

The problem of performing a precision landing of an autonomous multirotor UAV in various lighting conditions is studied. A vision-based approach is proposed and consists of varying degree-of-freedom image-based visual servoing (VDOF-IBVS), and a specialized landing marker. The proposed approach is validated through extensive flight testing outdoors in both lighted and dark conditions, and is done using a standard off-the-shelf autopilot system.


Electrochemical Glucose Sensors Enhanced By Methyl Viologen And Vertically Aligned Carbon Nanotube Channels, Benjamin J. Brownlee, Meisam Bahari, John H. Harb, Jonathan C. Claussen, Brian D. Iverson Aug 2018

Electrochemical Glucose Sensors Enhanced By Methyl Viologen And Vertically Aligned Carbon Nanotube Channels, Benjamin J. Brownlee, Meisam Bahari, John H. Harb, Jonathan C. Claussen, Brian D. Iverson

Faculty Publications

Free-standing, vertically aligned carbon nanotubes (VACNTs) were patterned into 16 μm diameter microchannel arrays for flow-through electrochemical glucose sensing. Non-enzymatic sensing of glucose was achieved by the chemical reaction of glucose with methyl viologen (MV) at an elevated temperature and pH (0.1 M NaOH), followed by the electrochemical reaction of reduced-MV with the VACNT surface. The MV sensor required no functionalization (including no metal) and was able to produce on average 3.4 electrons per glucose molecule. The current density of the MV sensor was linear with both flow rate and glucose concentration. Challenges with interference chemicals were mitigated ...


Total Hemispherical Apparent Radiative Properties Of The Infinite V-Groove With Diffuse Reflection, Rydge B. Mulford, Nathan S. Collins, Michael S. Farnsworth, Matthew R. Jones, Brian D. Iverson Jul 2018

Total Hemispherical Apparent Radiative Properties Of The Infinite V-Groove With Diffuse Reflection, Rydge B. Mulford, Nathan S. Collins, Michael S. Farnsworth, Matthew R. Jones, Brian D. Iverson

Faculty Publications

No abstract provided.


Bubble Nucleation In Superhydrophobic Microchannels Due To Subcritical Heating, Adam Cowley, Daniel Maynes, Julie Crockett, Brian D. Iverson Jun 2018

Bubble Nucleation In Superhydrophobic Microchannels Due To Subcritical Heating, Adam Cowley, Daniel Maynes, Julie Crockett, Brian D. Iverson

Faculty Publications

This work experimentally studies the effects of single wall heating on laminar flow in a high-aspect ratio superhydrophobic microchannel. When water that is saturated with air is used as the working liquid, the non-wetted cavities on the superhydrophobic surfaces act as nucleation sites and allow air to effervesce out of the water and onto the surface when heated. Previous works in the literature have only considered the opposite case where the water is undersaturated and absorbs air out the cavities for a microchannel setting. The microchannel considered in this work consists of a rib/cavity structured superhydrophobic surface and a ...


Universal Airfoil Parametrization Using B-Splines, Dev Rajnarayan, Andrew Ning, Judd Mehr Jun 2018

Universal Airfoil Parametrization Using B-Splines, Dev Rajnarayan, Andrew Ning, Judd Mehr

Faculty Publications

In this paper, we apply well-known techniques for parametric curves to the definition and deformation of airfoil sections. While it has already been shown that many versions of Kulfan’s Class Shape Transformation (CST) are exactly equivalent to Bézier curves, we show here that all NACA 4-digit thickness distributions and the PARSEC parametrization of Sobiezcky are also higher-order Bézier curves. As with CST, Béziers and B-Splines provide direct control over aerodynamically meaningful features such as nose radius and boat-tail angle, but also provide more a intuitive parametrization of the rest of the airfoil surface. We show the efficacy of B-Spline-based ...


Integrated Free-Form Method For Aerostructural Optimization Of Wind Turbine Blades, Ryan Barrett, Andrew Ning Apr 2018

Integrated Free-Form Method For Aerostructural Optimization Of Wind Turbine Blades, Ryan Barrett, Andrew Ning

Faculty Publications

A typical approach to optimize wind turbine blades separates the airfoil shape design from the blade planform design. This approach is sequential, where the airfoils along the blade span are pre-selected or optimized and then held constant during the blade planform optimization. In contrast, integrated blade design optimizes the airfoils and the blade planform concurrently and thereby has the potential to reduce cost of energy (COE) more than sequential design. Nevertheless, sequential design is commonly performed because of the ease of precomputation, or the ability to compute the airfoil analyses prior to the blade optimization. This research compares two integrated ...


Total Hemispherical Apparent Radiative Properties Of The Infinite V-Groove With Specular Reflection, Rydge B. Mulford, Nathan S. Collins, Michael S. Farnsworth, Matthew R. Jones, Brian D. Iverson Mar 2018

Total Hemispherical Apparent Radiative Properties Of The Infinite V-Groove With Specular Reflection, Rydge B. Mulford, Nathan S. Collins, Michael S. Farnsworth, Matthew R. Jones, Brian D. Iverson

Faculty Publications

Multiple reflections in a cavity geometry augment the emission and absorption of the cavity opening relative to a flat surface in a phenomenon known as the cavity effect. The extent of the cavity effect is quantified using apparent absorptivity and apparent emissivity. Analysis of complicated thermal systems is simplified through application of apparent radiative properities to cavity geometries. The apparent radiative properties of a specularly-reflecting, gray, isothermal V-groove have been derived analytically, but these results have not been validated experimentally or numerically. Additionally, the model for apparent absorptivity of an infinite V-groove subjected to partial illumination in the presence of ...


Symmetric Equations For Evaluating Maximum Torsion Stress Of Rectangular Beams In Compliant Mechanisms, Guimin Chen, Larry L. Howell Feb 2018

Symmetric Equations For Evaluating Maximum Torsion Stress Of Rectangular Beams In Compliant Mechanisms, Guimin Chen, Larry L. Howell

Faculty Publications

There are several design equations available for calculating the torsional compliance and the maximum torsion stress of a rectangular cross-section beam, but most depend on the relative magnitude of the two dimensions of the cross-section (i.e., the thickness and the width). After reviewing the available equations, two thickness-to-width ratio independent equations that are symmetric with respect to the two dimensions are obtained for evaluating the maximum torsion stress of rectangular cross-section beams. Based on the resulting equations, outside lamina emergent torsional joints are analyzed and some useful design insights are obtained. These equations, together with the previous work on ...


A Method For Characterizing Essential Tremor From The Shoulder To The Wrist, Daniel W. Geiger, Dennis Eggett, Steven K. Charles Feb 2018

A Method For Characterizing Essential Tremor From The Shoulder To The Wrist, Daniel W. Geiger, Dennis Eggett, Steven K. Charles

Faculty Publications

Background

Despite the pervasive and devastating effect of Essential Tremor (ET), the distribution of ET throughout the upper limb is unknown. We developed a method for characterizing the distribution of ET and performed a preliminary characterization in a small number of subjects with ET.

Methods

Using orientation sensors and inverse kinematics, we measured tremor in each of the seven major degrees of freedom (DOF) from the shoulder to the wrist while ten patients with mild ET assumed 16 different postures. We described the tremor in each DOF in terms of power spectral density measures and investigated how tremor varied between ...


Distributed Electric Propulsion Effects On Traditional Aircraft Through Multidisciplinary Optimization, Kevin Moore, Andrew Ning Jan 2018

Distributed Electric Propulsion Effects On Traditional Aircraft Through Multidisciplinary Optimization, Kevin Moore, Andrew Ning

Faculty Publications

Electric aircraft face a steep tradeoff between the demand for runway performance and range. While fuel based propulsion technologies typically increase in specific power with increasing size, electric propulsion is typically much more scalable. This system scalability enables alternative designs including distributed propulsion, optionally powered propulsion units, and vectored thrust, which can all contribute to better runway performance and range. In this paper, we explore how continuously powered distributed propulsion can reduce takeoff distance while still satisfying range constraints. We use a combination of a blade element momentum method, a vortex lattice method, experimental data, and nonlinear optimization techniques to ...


Multidisciplinary Design Optimization Of Flexible Solar-Regenerative High-Altitude Long-Endurance Aircraft, Taylor Mcdonnell, Judd Mehr, Andrew Ning Jan 2018

Multidisciplinary Design Optimization Of Flexible Solar-Regenerative High-Altitude Long-Endurance Aircraft, Taylor Mcdonnell, Judd Mehr, Andrew Ning

Faculty Publications

Solar-Regenerative High-Altitude Long-Endurance (SR-HALE) aircraft are designed to sustain year-round flight at high altitudes indefinitely. No SR-HALE aircraft has yet accomplished this task due to the complex network of environmental, solar, structural, and aerodynamic trade-offs, among which aircraft flexibility plays a key role. A comprehensive SR-HALE aircraft multidisciplinary design optimization framework is developed in which the flexible aircraft analysis tool ASWING is incorporated in order to constrain nonlinear aeroelasticity. Energy, battery, ply thickness, material failure, local buckling, aerodynamic stall, longitudinal stability, and general stability (including flutter) constraints are applied in order to reasonably constrain the optimized SR-HALE aircraft design. An ...


Benefits Of Two Turbine Rotor Diameters And Hub Heights In The Same Wind Farm, Andrew Pj Stanley, Andrew Ning, Katherine Dykes Jan 2018

Benefits Of Two Turbine Rotor Diameters And Hub Heights In The Same Wind Farm, Andrew Pj Stanley, Andrew Ning, Katherine Dykes

Faculty Publications

Significant turbine-wake interactions greatly reduce power output in a wind farm. If different turbine hub heights and rotor diameters are included in the same wind farm, the wake interference in the farm will be reduced, resulting in a lower cost of energy (COE) than a farm with identical turbines. In this paper, we present a method to model wind farm COE in farms with hub heights and rotor diameters that vary across the wind farm. We also demonstrate how to optimize these wind farms to minimize COE. The results show that COE can be greatly reduced in wind farms with ...


Large-Scale Multidisciplinary Optimization Of An Electric Aircraft For On-Demand Mobility, John Hwang, Andrew Ning Jan 2018

Large-Scale Multidisciplinary Optimization Of An Electric Aircraft For On-Demand Mobility, John Hwang, Andrew Ning

Faculty Publications

Distributed electric propulsion is a key enabling technology for on-demand electric aircraft concepts. NASA’s X-57 Maxwell X-plane is a demonstrator for this technology, and it features a row of high-lift propellers distributed along the leading edge of its wing to enable better aerodynamic efficiency at cruise and improved ride quality in addition to less noise and emissions. This study applies adjoint- based multidisciplinary design optimization to this highly coupled design problem. The propulsion, aerodynamics, and structures are modeled using blade element momentum theory, the vortex lat- tice method, and finite element analysis, respectively, and the full mission profile is ...


Trading Off Sound Pressure Level And Average Power Production For Wind Farm Layout Optimization, Eric Tingey, Andrew Ning Dec 2017

Trading Off Sound Pressure Level And Average Power Production For Wind Farm Layout Optimization, Eric Tingey, Andrew Ning

Faculty Publications

This research explores the trade-offs between a wind farm’s average power production and noise impact on nearby observers. Two specific wind farm designs were studied and optimized using the FLORIS wake model and an acoustic model based on semi-empirical turbine noise calculations. It was found in the two wind farms that the average power production could be increased, up to 8.01% in one and 3.63% in the other, ignoring sound level considerations. Including a noise restriction in the optimization had a minimal impact on the optimal average power production within about a five-decibel range. Past this range ...


Reaching In Clutter With Whole-Arm Tactile Sensing, Advait Jain, Marc D. Killpack, Aaron Edsinger, Charles Kemp Nov 2017

Reaching In Clutter With Whole-Arm Tactile Sensing, Advait Jain, Marc D. Killpack, Aaron Edsinger, Charles Kemp

Faculty Publications

Clutter creates challenges for robot manipulation, including a lack of non-contact trajectories and reduced visibility for line-of-sight sensors. We demonstrate that robots can use whole-arm tactile sensing to perceive clutter and maneuver within it, while keeping contact forces low. We first present our approach to manipulation, which emphasizes the benefits of making contact across the entire manipulator and assumes the manipulator has low-stiffness actuation and tactile sensing across its entire surface. We then present a novel controller that exploits these assumptions. The controller only requires haptic sensing, handles multiple contacts, and does not need an explicit model of the environment ...


Deep Visual Gravity Vector Detection For Unmanned Aircraft Attitude Estimation, Gary J. Ellingson, David Wingate, Tim Mclain Sep 2017

Deep Visual Gravity Vector Detection For Unmanned Aircraft Attitude Estimation, Gary J. Ellingson, David Wingate, Tim Mclain

Faculty Publications

This paper demonstrates a feasible method for using a deep neural network as a sensor to estimate the attitude of a flying vehicle using only flight video. A dataset of still images and associated gravity vectors was collected and used to perform supervised learning. The network builds on a previously trained network and was trained to be able to approximate the attitude of the camera with an average error of about 8 degrees. Flight test video was recorded and processed with a relatively simple visual odometry method. The aircraft attitude is then estimated with the visual odometry as the state ...


Relative Multiplicative Extended Kalman Filter For Observable Gps-Denied Navigation, Daniel P. Koch, David O. Wheeler, Randal Beard, Tim Mclain, Kevin M. Brink Aug 2017

Relative Multiplicative Extended Kalman Filter For Observable Gps-Denied Navigation, Daniel P. Koch, David O. Wheeler, Randal Beard, Tim Mclain, Kevin M. Brink

Faculty Publications

This work presents a multiplicative extended Kalman filter for estimating the relative state of a multirotor vehicle operating in a GPS-denied environment. The filter fuses data from an inertial measurement unit and altimeter with relative-pose updates from a keyframe-based visual odometry or laser scan-matching algorithm. Because the global position and heading states of the vehicle are unobservable in the absence of global measurements such as GPS, the filter in this paper estimates the state with respect to a local frame that is colocated with the odometry keyframe. As a result, the odometry update provides nearly-direct measurements of the relative vehicle ...


Improving The Floris Wind Plant Model For Compatibility With Gradient-Based Optimization, Jared Thomas, Pieter Gebraad, Andrew Ning Aug 2017

Improving The Floris Wind Plant Model For Compatibility With Gradient-Based Optimization, Jared Thomas, Pieter Gebraad, Andrew Ning

Faculty Publications

The FLOw Redirection and Induction in Steady-state (FLORIS) model, a parametric wind turbine wake model that predicts steady state wake characteristics based on wind turbine position and yaw angle, was developed for optimization of control settings and turbine locations. This paper provides details on the recent changes made to the FLORIS model to make the model more suitable for gradient-based optimization. Changes to the FLORIS model were made to remove discontinuities and add curvature to regions of non-physical zero gradient. Exact gradients for the FLORIS model were obtained using algorithmic differentiation. A set of three case studies demonstrate that using ...


Minimum Required Detection Range For Detect And Avoid Of Unmanned Aircraft Systems, Jared Kevin Wikle, Tim Mclain, Randal W. Beard, Laith Rasmi Sahawneh Jun 2017

Minimum Required Detection Range For Detect And Avoid Of Unmanned Aircraft Systems, Jared Kevin Wikle, Tim Mclain, Randal W. Beard, Laith Rasmi Sahawneh

Faculty Publications

For unmanned aircraft systems to gain full access to the National Airspace System, they must have the capability to detect and avoid other aircraft. To safely avoid an- other aircraft, an unmanned aircraft must detect the intruder aircraft with ample time and distance to allow the ownship to track the intruder, perform risk assessment, plan an avoidance path, and execute the maneuver. This paper describes two analytical methods for finding the minimum detection range to ensure that these detection and avoidance steps can be carried out. The first method, time-based geometric velocity vectors, includes the bank-angle dynamics of the ownship ...


Thermophysical Properties Of Thin Fibers Via Photothermal Quantum Dot Fluorescence Spectral Shape-Based Thermometry, Troy Munro, Liwang Liu, Heng Ban, Christ Glorieux Jun 2017

Thermophysical Properties Of Thin Fibers Via Photothermal Quantum Dot Fluorescence Spectral Shape-Based Thermometry, Troy Munro, Liwang Liu, Heng Ban, Christ Glorieux

Faculty Publications

To improve predictions of composite behavior under thermal loads, there is a need to measure the axial thermophysical properties of thin fibers. Current methods to accomplish this have prohibitively long lead times due to extensive sample preparation. This work details the use of quantum dots thermomarkers to measure the surface temperature of thin fibers in a non-contact manner and determine the fibers’ thermal diffusivity. Neural networks are trained on extracting the temperature of a sample from fluorescence spectra in calibrated, steady-state conditions, based on different spectral features such as peak intensity and peak wavelength. The trained neural networks are then ...


Estimating Human Intent For Physical Human-Robot Co-Manipulation, Eric Townsend, Erich Mielke, David Wingate, Marc D. Killpack May 2017

Estimating Human Intent For Physical Human-Robot Co-Manipulation, Eric Townsend, Erich Mielke, David Wingate, Marc D. Killpack

Faculty Publications

Human teams can be exceptionally efficient at adapting and collaborating during manipulation tasks using shared mental models. However, the same shared mental models that can be used by humans to perform robust low-level force and motion control during collaborative manipulation tasks are non-existent for robots. For robots to perform collaborative tasks with people naturally and efficiently, understanding and predicting human intent is necessary. However, humans are difficult to predict and model. We have completed an exploratory study recording motion and force for 20 human dyads moving an object in tandem in order to better understand how they move and how ...


Microstructure Correlation With Formability For Biaxial Stretching Of Magnesium Alloy Az31b At Mildly Elevated Temperatures, David T. Fullwood, Isaac Chelladurai, Michael P. Miles, John E. Carsley, Raj K. Mishra, Irene J. Beyerlein, Marko Knezevic May 2017

Microstructure Correlation With Formability For Biaxial Stretching Of Magnesium Alloy Az31b At Mildly Elevated Temperatures, David T. Fullwood, Isaac Chelladurai, Michael P. Miles, John E. Carsley, Raj K. Mishra, Irene J. Beyerlein, Marko Knezevic

Faculty Publications

Magnesium AZ31B sheets of 2 mm thickness were stretch formed using a 101.6 mm diameter punch at temperatures from 25°C - 150°C, in 25°C increments. Surface strains were measured using a digital image correlation (DIC) method. The punch height vs load curve was found to be the same for temperatures of 25°C and for 50°C, while at 75°C and above the load for a given punch height started to decrease, indicating a potential change in deformation mechanism. Electron Backscatter Diffraction (EBSD) was used to quantify features of the microstructure in the tested specimens. In ...


Optimization Under Uncertainty For Wake Steering Strategies, Julian Quick, Jennifer Annoni, Ryan King, Katherine Dykes, Paul Fleming, Andrew Ning May 2017

Optimization Under Uncertainty For Wake Steering Strategies, Julian Quick, Jennifer Annoni, Ryan King, Katherine Dykes, Paul Fleming, Andrew Ning

Faculty Publications

Wind turbines in a wind power plant experience significant power losses because of aerodynamic interactions between turbines. One control strategy to reduce these losses is known as 'wake steering,' in which upstream turbines are yawed to direct wakes away from downstream turbines. Previous wake steering research has assumed perfect information, however, there can be significant uncertainty in many aspects of the problem, including wind inflow and various turbine measurements. Uncertainty has significant implications for performance of wake steering strategies. Consequently, the authors formulate and solve an optimization under uncertainty (OUU) problem for finding optimal wake steering strategies in the presence ...


Thermal Characterization Of Natural And Synthetic Spider Silks By Both The 3Ω And Transient Electrothermal Methods, Troy Munro, Changhu Xing, Heng Ban, Cameron G. Copeland, Randolph V. Lewis, Colby Jensen Apr 2017

Thermal Characterization Of Natural And Synthetic Spider Silks By Both The 3Ω And Transient Electrothermal Methods, Troy Munro, Changhu Xing, Heng Ban, Cameron G. Copeland, Randolph V. Lewis, Colby Jensen

Faculty Publications

Thermal conductivity, thermal diffusivity and volumetric heat capacity of three spider silks are measured in this paper as a benchmark for further studies. These silks include the major and minor ampullate silks of the Nephila clavipes spider, and a synthetic spider silk fiber made from recombinant dragline silk proteins purified from transgenic goats’ milk. Two complementary measurement techniques are employed in the thermal characterization of these microscale single fibers for self-verification. One is the transient electrothermal technique (TET) and the other is the 3ω method. Experimental measurements indicate that thermal properties of the dragline silk are very close to those ...


Investigation Of Synthetic Spider Silk Crystallinity And Alignment Via Electrothermal, Pyroelectric, Literature Xrd, And Tensile Techniques, Troy Munro, Tristan Putzeys, Michael Wubbenhorst, Christ Glorieux, Cameron G. Copeland, Randolph V. Lewis, Changhu Xing, Heng Ban Apr 2017

Investigation Of Synthetic Spider Silk Crystallinity And Alignment Via Electrothermal, Pyroelectric, Literature Xrd, And Tensile Techniques, Troy Munro, Tristan Putzeys, Michael Wubbenhorst, Christ Glorieux, Cameron G. Copeland, Randolph V. Lewis, Changhu Xing, Heng Ban

Faculty Publications

The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the N. clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by XRD data. The results show that stretching and passage through liquid baths induce ...


Two-Phase Flow Pressure Drop In Superhydrophobic Channels, Kimberly A. Stevens, Julie Crockett, Daniel R. Maynes, Brian D. Iverson Mar 2017

Two-Phase Flow Pressure Drop In Superhydrophobic Channels, Kimberly A. Stevens, Julie Crockett, Daniel R. Maynes, Brian D. Iverson

Faculty Publications

Superhydrophobic surfaces have been shown to reduce drag in single-phase channel flow; however, little work has been done to characterize their drag-reducing ability found in two-phase flows. Adiabatic, airwater mixtures were used to explore the influence of hydrophobicity on two-phase flows and the hydrodynamics which might be present in flow condensation environments. Pressure drop measurements in a rectangular channel with one superhydrophobic wall (cross-section approximately 0.37 x 10 mm) and three transparent hydrophilic walls were obtained. Data for air/water mixtures with superficial Reynolds numbers ranging from 22–215 and 55–220, respectively, were obtained for superhydrophobic surfaces with ...


Influence Of Noise Generating Factors On Cross Correlation Ebsd Measurement Of Gnds, David T. Fullwood, Landon Hansen, Brian Jackson, Stewart I. Wright, Marc De Graef, Eric Richards Homer, Robert Wagoner Mar 2017

Influence Of Noise Generating Factors On Cross Correlation Ebsd Measurement Of Gnds, David T. Fullwood, Landon Hansen, Brian Jackson, Stewart I. Wright, Marc De Graef, Eric Richards Homer, Robert Wagoner

Faculty Publications

Studies of dislocation density evolution are fundamental to improved understanding in various areas of deformation mechanics. Recent advances in cross-correlation techniques, applied to EBSD data have particularly shed light on geometrically necessary dislocation (GND) behavior. However, the framework is relatively computationally expensive – patterns are typically saved from the EBSD scan and analyzed offline. A better understanding of the impact of EBSD pattern degradation, such as binning, compression, and various forms of noise, is vital to enable optimization of rapid and low cost GND analysis. This paper tackles the problem by setting up a set of simulated patterns that mimic real ...