Engineering Commons^™

Evolutionary View Planning For Optimized Uav Terrain Modeling In A Simulated Environment, Ronald A. Martin, Ivan Rojas, Kevin W. Franke, John Hedengren

Faculty Publications

This work demonstrates the use of genetic algorithms in optimized view planning for 3D reconstruction applications using small unmanned aerial vehicles (UAVs). The quality of UAV site models is currently highly dependent on manual pilot operations or grid-based automation solutions. When applied to 3D structures, these approaches can result in gaps in the total coverage or inconsistency in final model resolution. Genetic algorithms can effectively explore the search space to locate image positions that produce high quality models in terms of coverage and accuracy. A fitness function is defined, and optimization parameters are selected through semi-exhaustive search. A novel simulation …

Integrated Design Of Downwind Land-Based Wind Turbines Using Analytic Gradients, Andrew Ning, Derek Petch

Faculty Publications

Wind turbines are complex systems where component-level changes can have significant system-level effects. Effective wind turbine optimization generally requires an integrated analysis approach with a large number of design variables. Optimizing across large variable sets is orders of magnitude more efficient with gradient-based methods as compared to gradient-free method, particularly when using exact gradients. We have developed a wind turbine analysis set of over 100 components where 90% of the models provide numerically exact gradients through symbolic differentiation, automatic differentiation, and adjoint methods. This framework is applied to a specific design study focused on downwind land-based wind turbines.

Downwind machines …

Quantum Dot Band Gap Investigations, John Ryan Peterson

Student Works

Improving solar panel efficiency has become increasingly important as the world searches for cheap renewable energy. Recent developments in the industry have focused on multi-layer cells, some of which use semiconducting dyes to absorb light in place of crystalline solids. In this paper, I characterize various dyes recently synthesized for use in solar panels. These dyes contain semiconducting nanoparticles enclosed primarily by the protein ferritin to limit particle size. The band gaps were measured using either optical absorption spectroscopy or measuring the photoluminescence spectrum, depending on the type of semiconductor. The results indicate that both manganese oxide and lead sulfide …

Material Selection Shape Factors For Compliant Arrays In Bending, David T. Fullwood, Todd G. Nelson, Jared T. Bruton, Nathan E. Rieske, M. Patrick Walton, Larry L. Howell

Faculty Publications

Similar to the general class of metamaterials, compliant arrays (CAs) are engineered from an array of subelements that combine to produce a response that is typically not available from a at panel made of a single material. As such, analysis and design of CA systems requires the integration of both the material and geometrical properties of the array. This paper proposes a convenient and efficient method of combining these essential elements using analytically derived shape factors for bending modes. The approach is validated experimentally, and used to demonstrate large regions of previously inaccessible property combinations in material selection charts that …

Vibration Monitoring Via Nano-Composite Piezoelectric Foam Bushings, David T. Fullwood, Evan T. Bird, A Jake Merrell, Brady K. Anderson, Cory N. Newton, Parker G. Rosquist, Anton E. Bowden, Matthew K. Seeley

Faculty Publications

Most mechanical systems produce vibrations as an inherent side effect of operation. Though some vibrations are acceptable in operation, others can cause damage or signal a machine’s imminent failure. These vibrations would optimally be monitored in real-time, without human supervision to prevent failure and excessive wear in machinery. This paper explores a new alternative to currently-used machine-monitoring equipment, namely a piezoelectric foam sensor system. These sensors are made of a silicone-based foam embedded with nano- and micro-scale conductive particles. Upon impact, they emit an electric response that is directly correlated with impact energy, with no electrical power input. In the …

Development And Optimization Of Voltammetry For Real Time Analysis Of Multi-Component Electrorefiner Salt, Chao Zhang, Devin Rappleye, Michael F. Simpson

Faculty Publications

Normal pulse voltammetry was performed on LiCl-KCl-UCl3- MgCl2 molten salt mixtures while varying parameters such as pulse time, relaxation potential, and interval time. Concentrations of UCl3 up to 7 wt% were tested with a fixed 1.5 wt% MgCl2 concentration. The correlation between diffusion limited partial current density to UCl3 concentration exhibited an excellent fit to a 2nd order polynomial. A similar fit was obtained for the correlation between MgCl2 concentration and the diffusion limited partial current density at a fixed UCl3 concentration of 1.0 wt%.

Polynomial Chaos For The Computation Of Annual Energy Production In Wind Farm Layout Optimization, Santiago Padrón, Andrew P.J. Stanley, Jared Thomas, Juan Alonso, Andrew Ning

Faculty Publications

Careful management of wake interference is essential to further improve Annual Energy Production (AEP) of wind farms. Wake effects can be minimized through optimization of turbine layout, wind farm control, and turbine design. Realistic wind farm optimization is challenging because it has numerous design degrees of freedom and must account for the stochastic nature of wind. In this paper we provide a framework for calculating AEP for any relevant uncertain (stochastic) variable of interest. We use Polynomial Chaos (PC) to efficiently quantify the effect of the stochastic variables—wind direction and wind speed—on the statistical outputs of interest (AEP) for wind …

Scenario Analysis For Techno-Economic Model Development Of U.S. Offshore Wind Support Structures, Rick Damiani, Andrew Ning, Ben Maples, Aaron Smith, Katherine Dykes

Faculty Publications

Challenging bathymetry and soil conditions of future U.S. offshore wind power plants might promote the use of multimember, fixed-bottom structures (or “jackets”) in place of monopiles. Support structures affect costs associated with the balance of system (BOS) and operation and maintenance. Understanding the link between these costs and the main environmental design drivers is crucial in the quest for a lower levelized cost of energy (LCOE), and it is the main rationale for this work. Actual cost and engineering data are still scarce; hence, we evaluated a simplified engineering approach to tie key site and turbine parameters (e.g., water depth, …

A New Open Source Platform For Lowering The Barrier For Environmental Web App Development, Nathan R. Swain, Scott D. Christensen, Alan D. Snow, Herman Dolder, Gonzola Espinoza-Dávalos, Erfan Goharian, Norman L. Jones, E. James Nelson, Daniel P. Ames, Steven J. Burian

Faculty Publications

The interactive nature of web applications or “web apps” makes them a well-suited medium for conveying complex scientific concepts to lay audiences and creating decision support tools that harness cutting edge modeling techniques and promote the work of environmental scientists and engineers. Despite this potential, the technical expertise required to develop web apps represents a formidable barrier—even for scientists and engineers who are skilled programmers. This paper describes four hurdles that contribute to this barrier and introduces an approach to overcoming these hurdles. We present an open source implementation of this approach, a development and hosting environment for environmental web …

Open-Loop Electrowetting Actuation With Micro-Stepping, Qi Ni, Daniel E. Capecci, Nathan B. Crane

Faculty Publications

Microfluidic-driven mechanical actuation opens new possibilities for positioning and manipulating delicate small components. However, existing microfluidic actuation methods are not well-suited to positioning with high resolution. This paper reports a method for precise, open-loop control of droplet position in finite steps by varying the duty cycle of the input signal in electrowetting actuation. When wetted to a solid object, both the droplet and the solid can be actuated. Unlike conventional electrowetting actuation methods, positioning resolution in our proposed method can be much smaller than the size of the underlying electrodes without requiring closed loop feedback control system. Using a leaky …

Performance Of Dynamically Simulated Reference Patterns For Cross Correlation Ebsd, Brian Jackson, Jordan Christensen, Saransh Singh, Marc De Graef, David T. Fullwood, Eric Richards Homer, Robert Wagoner

Faculty Publications

High-resolution (or \cross-correlation") electron backscatter diffraction analysis (HR-EBSD) utilizes cross-correlation techniques to determine relative orientation and distortion of an experimental electron backscatter diffraction pattern (EBSP) with respect to a reference pattern. The integrity of absolute strain and tetragonality measurements of a standard Si/SiGe material have previously been analyzed using reference patterns produced by kinematical simulation. While the results were promising, the noise levels were significantly higher for kinematically produced patterns, compared to real patterns taken from the Si region of the sample. This paper applies HR-EBSD techniques to analyze lattice distortion in a Si/SiGe sample, using recently developed dynamically simulated …

Application Of Voltammetry For Electroanalytical Measurement Of Concentrations In Lacl3-Mgcl2 Mixtures In Eutectic Licl-Kcl, Zhonghang Wang, Devin Rappleye, C S. Yang, Michael Simpson

Faculty Publications

For electroanalytical measurement of molten chloride salts, various voltammetry methods have been used on mixtures of MgCl₂ and LaCl₃ in eutectic LiCl-KCl. These salt mixtures are of primary interest to spent nuclear fuel electrorefining systems. MgCl₂ is used as a surrogate for PuCl₃, while LaCl₃ represents rare earth fission product salts. Cyclic voltammetry scans with these salt mixtures exhibited extra peaks, presumably due to underpotential deposition of La(III) ions onto Mg. Quantitatively, the current contribution from each peak was best determined using normal pulse voltammetry and fit to the Cottrell equation. This yielded linear …

Robust Bi-Directional Continuous Electrowetting Based On Metal-Semiconductor (M-S) Diodes, Qi Ni, Daniel E. Capecci, Millicent Schlafly, Nathan B. Crane

Faculty Publications

We demonstrate bi-directional continuous electrowetting by embedding metal-semiconductor diodes in the electrowetting substrate. Unlike conventional electrowetting on dielectric (EWOD), bi-directional continuous electrowetting uses a single electrode pair to actuate a droplet through long distances. As long as the voltage potential is maintained between two end electrodes, the droplet moves toward the electrode with the higher potential. However, previously reported material systems had limited success in repeated actuation. In this work, diodes based on Schottky barriers were fabricated by forming metal-semiconductor junctions between titanium and high resistivity n-type silicon. The performance enhancements were evaluated using current-voltage measurements of interface pairs. When …

Comparison Of Sfm Computer Vision Point Clouds Of A Landslide Derived From Multiple Small Uav Platforms And Sensors To A Tls Based Model, Samantha Ruggles, Joseph Clark, Kevin W. Franke, Derek Wolfe, Brandon Reimschiissel, Ronald Abraham Martin, Trent Okeson, John Hedengren

Faculty Publications

Structure from motion (SfM) computer vision is a remote sensing method that is gaining popularity due to its simplicity and ability to accurately characterize site geometry in three dimensions (3D). While many researchers have demonstrated the potential for SfM to be used with unmanned aerial vehicles (UAVs) to model in three dimensions various geologic features such as landslides, little is understood how the selection of the UAV platform can affect the resolution and accuracy of the model. This study evaluates the resolution and accuracy of 3D point cloud models of a large landslide that occurred in 2013 near Page, Arizona …

Insights Into Twinning In Mg Az31: A Combined Ebsd And Machine Learning Study, David T. Fullwood, Andrew Orme, Isaac Chelladurai, Travis Michael Rampton, Ali Khosravani, Michael Miles, Raj K. Mishra

Faculty Publications

To explore the driving forces behind deformation twinning in Mg AZ31, a machine learning framework is utilized to mine data obtained from electron backscatter diffraction (EBSD) scans in order to extract correlations in physical characteristics that cause twinning. The results are intended to inform physics-based models of twin nucleation and growth. A decision tree learning environment is selected to capture the relationships between microstructure and twin formation; this type of model effectively highlights the more influential characteristics of the local microstructure. Trees are assembled to analyze both twin nucleation in a given grain, and twin propagation across grain boundaries. Each …

Comparison Of Airfoil Precomputational Analysis Methods For Optimization Of Wind Turbine Blades, Ryan Barrett, Andrew Ning

Faculty Publications

The objective of this research was to develop and compare various airfoil precomputational parameterization and analysis techniques for aerostructural optimization of wind turbine blades. The airfoils along the blade were added as optimization design variables through pre-computational parameterization methods using thickness-to-chord ratios and blended airfoil family factors. The airfoils' aerodynamic performance was analyzed with three methods of increasing fidelity: a panel method (XFOIL), Navier-Stokes based computational fluid dynamics (RANS CFD), and wind tunnel data. The optimizations minimized mass over annual energy production (m/AEP) and thereby approximated the minimization of cost of energy. The results were compared to the NREL 5-MW …

Cushioned Extended-Periphery Avoidance: A Reactive Obstacle Avoidance Plugin, Timothy Mclain, James Jackson, David Wheeler

Faculty Publications

While collision avoidance and flight stability are generally a micro air vehicle’s (MAVs) highest priority, many map-based path planning algorithms focus on path optimality, often assuming a static, known environment. For many MAV applications a robust navigation solution requires responding quickly to obstacles in dynamic, tight environments with non- negligible disturbances. This article first outlines the Reactive Obstacle Avoidance Plugin framework as a method for leveraging map-based algorithms while providing low-latency, high-bandwidth response to obstacles. Further, we propose and demonstrate the effectiveness of the Cushioned Extended- Periphery Avoidance (CEPA) algorithm. By representing recent laser scans in the current body-fixed polar …

Rosflight: A Lightweight, Inexpensive Mav Research And Development Tool, Timothy Mclain, James Jackson, Gary J. Ellingson

Faculty Publications

To accelerate research and development of the autonomous capabilities of micro aerial vehicles we have developed flight control framework, ROSflight, as a research tool. ROSflight makes development of autopilot code easier and more efficient by minimizing the use of embedded systems, incorporating the Robot Operating System and using off-the-shelf and open-source hardware and software. Motivation and applications for use in the research community are discussed. Analysis of loop rate and communication bandwidth are presented as well as results from flight demonstration of two multi-rotor aircraft.

Modeling And Control Of A Tailsitter With A Ducted Fan, Matthew Elliott Argyle

Student Works

There are two traditional aircraft categories: fixed-wing which have a long endurance and a high cruise airspeed and rotorcraft which can take-off and land vertically. The tailsitter is a type of aircraft that has the strengths of both platforms, with no additional mechanical complexity, because it takes off and lands vertically on its tail and can transition the entire aircraft horizontally into high-speed flight. In this dissertation, we develop the entire control system for a tailsitter with a ducted fan. The standard method to compute the quaternion-based attitude error does not generate ideal trajectories for a hovering tailsitter for some …

An Investigation Of The Impact A Rov Competition Curriculum Has On Student Interest In Stem, Specifically Technology And Engineering, Daniel Gordon Bates

Student Works

This research investigates the impact a Remotely Operated Vehicle (ROV) program has on student interest in, and perception of, technology and engineering (sTEm). ROV programs embed areas of science, technology, engineering and math (STEM) into their curriculum; however, emphasis for this study is placed on interest and perception of the "T" and "E" of STEM. Although there are many articles detailing the benefits of ROV programs, there is little empirical data documenting the impact on student interest and perception of sTEm. This study outlines the background of a few major ROV programs in the U.S.; specifically Utah Underwater Robotics (UUR), …

Jezik: A Cognitive Translation System Employing A Single, Visible Spectrum Tracking Detector, Davor Bzik

Student Works

A link between eye movement mechanics and the mental processing associated with text reading has been established in the past. The pausing of an eye gaze on a specific word within a sentence reflects correctness or fluency of a translated text. A cognitive translation system has been built employing a single, inexpensive web camera without the use of infrared illumination. It was shown that the system translates the text, detects rarely occurring and out-of-context words from eye gaze information, and provides solutions in real time while the user is still reading. The solutions are in form of a translation, definition …

Uav Path-Planning Using Bézier Curves And A Receding Horizon Approach, Bryce Ingersoll, Kyle Ingersoll, Patrick Defranco, Andrew Ning

Faculty Publications

Unmanned aerial vehicles (UAVs) are used in an increasing number of applications. Such applications may include navigating through heavy traffic and highly congested airways, where numerous static and dynamic obstacles impinge upon a UAV's flight. It is imperative that a UAV successfully avoids these obstacles, while improving its planned flight path according to certain criteria. We have modeled UAV path planning as a single objective optimization problem that utilizes a receding horizon approach, where the path is constrained to avoid obstacle collision and to account for flight aerodynamic constraints. The proposed method is gradient based, allowing for quick and robust …

Multi-Sensor Robust Relative Estimation Framework For Gps-Denied Multirotor Aircraft, Tim Mclain, Daniel P. Koch, Kevin M. Brink

Faculty Publications

An estimation framework is presented that improves the robustness of GPS-denied state estimation to changing environmental conditions by fusing updates from multiple view-based odometry algorithms. This allows the vehicle to utilize a suite of complementary exteroceptive sensors or sensing modalities. By estimating the vehicle states relative to a local coordinate frame collocated with an odometry keyframe, observability of the relative state is maintained. A description of the general framework is given, as well as the specific equations for a multiplicative extended Kalman filter with a multirotor vehicle. Experimental results are presented that demonstrate the ability of the proposed algorithm to …

High Density 3d Printed Microfluidic Valves, Pumps, And Multiplexers, Hua Gong, Adam T. Woolley, Gregory P. Nordin

Faculty Publications

In this paper we demonstrate that 3D printing with a Digital Light Processor stereolithographic (DLP-SLA) 3D printer can be used to create high density microfluidic devices with active components such as valves and pumps. Leveraging our previous work on optical formulation of inexpensive resins (RSC Adv. 5, 106621, 2015), we demonstrate valves with only 10% of the volume of our original 3D printed valves (Biomicrofluidics 9, 016501, 2015), which were already the smallest that have been reported. Moreover, we show that inclusion of a thermal initiator in the resin formulation along with a post-print bake can dramatically improve the durability …

Relative Navigation In Gps Degraded Environments, Timothy Mclain, David Wheeler, Paul W. Nyholm, Daniel P. Koch, Gary J. Ellingson, Benjamin J. Lewis, Randall W. Beard

Faculty Publications

For unmanned aircraft systems to become fully integrated into society, safe and reliable methods for estimation and control are required even when global measurements such as GPS are degraded or unavailable. In these situations, estimating the vehicle's global state directly leads to inaccuracy and inconsistency. The relative navigation framework avoids these issues by estimating the vehicle's state with respect to a current local coordinate frame associated with a visual odometry algorithm. A globally consistent and localized pose-graph map is produced by compounding these local estimates and opportunistically incorporating additional constraints such as GPS measurements and loop closures. This architecture increases …

Microspine Gripping Mechanism For Asteroid Capture, Ezekiel G. Merriam, Andrew B. Berg, Andrew Willig, Aaron Parness, Tim Frey, Larry L. Howell

Student Works

This paper details the development and early testing of a compliant suspension for a microspine gripper device for asteroid capture or micro-gravity percussive drilling. The microspine gripper architecture is reviewed, and a proposed microspine suspension design is presented and discussed. Prototyping methods are discussed, as well as testing methods and results. A path forward is identified from the results of the testing completed thus far. Key findings include: the microspine concept has been established as a valid architecture and the compliant suspension exhibits the desired stiffness characteristics for good gripping behavior. These developments will aid in developing the capability to …

Maximization Of The Annual Energy Production Of Wind Power Plants By Optimization Of Layout And Yaw-Based Wake Control, Pieter Gebraad, Jared Thomas, Andrew Ning, Paul Fleming, Katherine Dykes

Faculty Publications

This paper presents a wind plant modeling and optimization tool that enables the maximization of wind plant annual energy production (AEP) using yaw-based wake steering control and layout changes. In order to make predictions of wind plant AEP, necessary extensions of the original wind plant wake interaction model include the coupling with a detailed rotor model and a control policy for turbine blade pitch and rotor speed. This coupling allows the prediction of power production with wake effects throughout a range of wind speeds. Results of an optimization study on a wind plant based on the Princess Amalia Wind Park …

An Overview Of Current Applications, Challenges, And Future Trends In Distributed Process-Based Models In Hydrology, Simone Fatichi, Enrique R. Vivoni, Fred L. Ogden, Valeriy Y. Ivanov, Benjamin Mirus, David Gochis, Charles W. Downer, Matteo Camporese, Jason H. Davidson, Brian Ebel, Norm Jones, Jongho Kim, Giuseppe Mascaro, Richard Niswonger, Pedro Restrepo, Riccardo Rigon, Chaopeng Shen, Mauro Sulis, David Tarboton

Faculty Publications

Process-based hydrological models have a long history dating back to the 1960s. Criticized by some as over-parameterized, overly complex, and difficult to use, a more nuanced view is that these tools are necessary in many situations and, in a certain class of problems, they are the most appropriate type of hydrological model. This is especially the case in situations where knowledge of flow paths or distributed state variables and/or preservation of physical constraints is important. Examples of this include: spatiotemporal variability of soil moisture, groundwater flow and runoff generation, sediment and contaminant transport, or when feedbacks among various Earth’s system …

A Continuous Formulation For Logical Decisions In Differential Algebraic Systems Using Mathematical Programs Of Complementarity Constraints, Kody Powell, Ammon N. Eaton, John Hedengren, Thomas F. Edgar

Faculty Publications

This work presents a methodology to represent logical decisions in differential algebraic equation simulation and constrained optimization problems using a set of continuous algebraic equations. The formulations may be used when state variables trigger a change in process dynamics, and introduces a pseudo-binary decision variable, which is continuous, but should only have valid solutions at values of either zero or one within a finite time horizon. This formulation enables dynamic optimization problems with logical disjunctions to be solved by simultaneous solution methods without using methods such as mixed integer programming. Several case studies are given to illustrate the value of …

Towards Developing Product Applications Of Thick Origami Using The Offset Panel Technique, Michael R. Morgan, Robert J. Lang, Spencer P. Magleby, Larry L. Howell

Faculty Publications

Several methods have been developed to accommodate for the use of thick materials in origami models which preserve either the model’s full range of motion or its kinematics. The offset panel technique (OPT) preserves both the range of motion and the kinematics while allowing for a great deal of flexibility in design. This work explores new possibilities for origami-based product applications presented by the OPT. Examples are included to illustrate fundamental capabilities that can be realized with thick materials such as accommodation of various materials in a design and manipulation of panel geometry resulting in an increased stiffness and strength. …