Engineering Commons^™

The Effect Of Projectile Nose Shape On The Formation Of The Water Entry Cavity, Jeremy Conrad Ellis

Theses and Dissertations

This research focuses on the effect of several convex and concave nose shapes on cavity formation for both hydrophilic and hydrophobic projectiles. It specifically investigates the effect of convex shape on the threshold velocity for cavity formation as well as the effect of concave shapes on cavity formation in terms of impact velocity, geometry of the concave shape and wettability of the projectile. For the convex cases, the streamlined axisymmetric shape significantly increases the threshold velocity when cavities form and is most pronounced for the ogive and cone. The study demonstrates that measuring the wetting angle and impact velocity is …

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 …

Computing Research In Academia: Classifications, Keywords, Perceptions, And Connections, Sung Han Kim

Theses and Dissertations

The Association for Computing Machinery (ACM) recognizes five computing disciplines: Computer Science (CS), Computer Engineering (CE), Information Technology (IT), Information Systems (IS), and Software Engineering (SE). Founded in 1947 the ACM is the world's largest society for computing educators, researchers, and professionals. While Computer Science has been a degree program since 1962, the other four are relatively new. This research focuses on understanding the graduate research in four of the five ACM disciplines (CS, CE, IT, and IS) using a large body of thesis and dissertation metadata. SE is not found in the metadata and graduate work in SE is …

Error Propagation Dynamics Of Piv-Based Pressure Field Calculation, Zhao Pan

Theses and Dissertations

Particle Image Velocimetry (PIV) based pressure field calculation is becoming increasingly popular in experimental fluid dynamics due to its non-intrusive nature. Errors propagated from PIV results to pressure field calculations are unavoidable, and in most cases, non-negligible. However, the specific dynamics of this error propagation process have not been unveiled. This dissertation examines both why and how errors in the experimental data are propagated to the pressure field by direct analysis of the pressure Poisson equation. Error in the pressure calculations are bounded with the error level of the experimental data. The error bounds quantitatively explain why and how many …

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 …

Automatic Dependent Surveillance-Broadcast For Detect And Avoid On Small Unmanned Aircraft, Matthew Owen Duffield

Theses and Dissertations

Small unmanned aircraft systems (UAS) are rapidly gaining popularity. As the excitement surrounding small UAS has grown, the Federal Aviation Administration (FAA) has repeatedly stated that UAS must be capable of detecting and avoiding manned and unmanned aircraft. In developing detect-and-avoid (DAA) technology, one of the key challenges is identifying a suitable sensor. Automatic Dependent Surveillance-Broadcast (ADS-B) has gained much attention in both the research and consumer sectors as a promising solution. While ADS-B has many positive characteristics, further analysis is necessary to determine if it is suitable as a DAA sensor in environments with high-density small UAS operations. To …

Assessing User Expectations Of Undo In A Multi-User Cad Environment, Jeffrey Eric Nuss

Theses and Dissertations

Undo is a command that users rely on in most software applications. Its importance in multi-user CAD is no different. However, due to its unique nature, users may have different expectations regarding how undo should behave. This research seeks to better understand users' expectations regarding undo in multi-user CAD by having users participate in collaborative design exercises and then asking them how they would expect undo to behave. In addition, users participated in a survey in which they watched 8 videos showing users interacting within multi-user CAD and were then asked about how they would want undo to behave. Based …

Stiffness Reduction Strategies For Additively Manufactured Compliant Mechanisms, Ezekiel G. Merriam

Theses and Dissertations

This work develops and examines design strategies for reducing the stiffness of 3D-printed compliant mechanisms. The three aspects of a flexure that determine its stiffness are well known: material, boundary conditions, and geometry. In a highly constrained design space however, flexure stiffness may remain unacceptably high even while arriving at the limits of design constraints. In this work, changes to geometry and boundary conditions are examined that lead to drastically reduced stiffness behavior without changing flexure thickness, width, or length. Changes to geometry can result in very complex mechanisms. However, 3D printing enables almost arbitrarily complex geometries. This dissertation presents …

Droplet Impingement On Superhydrophobic Surfaces, Cristian Esteban Clavijo Angeles

Theses and Dissertations

This dissertation explores the physics of droplet impingement on superhydrophobic surfaces. The research is divided in three categories. First, the effect of a slip boundary condition on droplet spreading/retracting is considered. A model is developed based on energy conservation to evaluate spreading rates on surfaces exhibiting isotropic and anisotropic slip. The results show that larger slip causes the droplet to spread out farther owing to reduced friction at the interface for both slip scenarios. Furthermore, effects of slip become magnified for large Weber numbers due to the larger solid-liquid contact area during the process. On surfaces with anisotropic slip, droplets …

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. …

Mentored Environment For Isogeometric Analysis, Kevin Tew, Michael Scott

Journal of Undergraduate Research

The mentored environment for isogeometric analysis (IGA) has trained engineering and computer science students to develop isogeometric numerical methods and accompanying software to solve challenging problems in science and engineering. The mentoring environment consisted of:

1. Weekly group meetings where research concepts were discussed, scientific literature was reviewed, and progress was monitored.
2. Pairing of students with a faculty members to develop IGA design-through-analysis methodologies.
3. Preparation of results for peer-reviewed publications.

Conjugate Heat Transfer And Average Versus Variable Heat Transfer Coefficients, Tyler James Macbeth

Theses and Dissertations

An average heat transfer coefficient, h_bar, is often used to solve heat transfer problems. It should be understood that this is an approximation and may provide inaccurate results, especially when the temperature field is of interest. The proper method to solve heat transfer problems is with a conjugate approach. However, there seems to be a lack of clear explanations of conjugate heat transfer in literature. The objective of this work is to provide a clear explanation of conjugate heat transfer and to determine the discrepancy in the temperature field when the interface boundary condition is approximated using h_bar compared to …

In Vitro Molecular Modification Of Human Cultured And Primary Cells Using Lance Array Nanoinjection, John W. Sessions

Theses and Dissertations

Fundamentally altering cellular function at a genetic level is a major area of interest in the biologic sciences and the medical community. By engineering transfectable constructs that can be inserted to dysfunctional cellular systems, scientists can mitigate aberrant genetic behavior to produce proper molecular function. While viral vectors have been a mainstay in the past, there are many limitations, particularly related to safety, that have changed the focus of genome editing to incorporate alternative methods for gene delivery. Lance Array Nanoinjection (LAN), a second-generation microfabricated transfection biotechnology, is one of these alternative technologies. LAN works by utilizing both simultaneous electrostatic …

An Automated Method For Optimizing Compressor Blade Tuning, Kurt Berlin Hinkle

Theses and Dissertations

Because blades in jet engine compressors are subject to dynamic loads based on the engine's speed, it is essential that the blades are properly "tuned" to avoid resonance at those frequencies to ensure safe operation of the engine. The tuning process can be time consuming for designers because there are many parameters controlling the geometry of the blade and, therefore, its resonance frequencies. Humans cannot easily optimize design spaces consisting of multiple variables, but optimization algorithms can effectively optimize a design space with any number of design variables. Automated blade tuning can reduce design time while increasing the fidelity and …

Analysis Of High Fidelity Turbomachinery Cfd Using Proper Orthogonal Decomposition, Ronald Alex Spencer

Theses and Dissertations

Assessing the impact of inlet flow distortion in turbomachinery is desired early in the design cycle. This thesis introduces and validates the use of methods based on the Proper Orthogonal Decomposition (POD) to analyze clean and 1/rev static pressure distortion simulation results at design and near stall operating condition. The value of POD comes in its ability to efficiently extract both quantitative and qualitative information about dominant spatial flow structures as well as information about temporal fluctuations in flow properties. Observation of the modes allowed qualitative identification of shock waves as well as quantification of their location and range of …

Understanding And Addressing Collaboration Challenges For The Effective Use Of Multi-User Cad, David James French

Theses and Dissertations

Multi-user computer-aided design (CAD) is an emerging technology that promises to facilitate collaboration, enhance product quality, and reduce product development lead times by allowing multiple engineers to work on the same design at the same time. The BYU site of the NSF Center for e-Design has developed advanced multi-user CAD prototypes that have demonstrated the feasibility and value of this technology. Despite the possibilities that this software opens up for enhanced collaboration, there are now a new variety of challenges and opportunities to understand and address. For multi-user CAD to be used effectively in a modern engineering environment, it is …

Decomposition Of Manufacturing Processes For Multi-User Tool Path Planning, Andrew Scherbel Priddis

Theses and Dissertations

Engineering activities by nature are collaborative endeavors. Single-user applications like CAD, CAE, and CAM force a strictly serial design process, which ultimately lengthens time to market. New multi-user applications such as NXConnect address the issue during the design stage of the product development process by enabling users to work in parallel. Multi-user collaborative tool path planning software addresses the same serial limitations in tool path planning, thereby decreasing cost and increasing the quality of manufacturing processes. As part complexity increases, lead times are magnified by serial workflows. Multi-user tool path planning can shorten the process planning time. But, to be …

Neutral Parametric Database, Server, Logic Layers, And Clients To Facilitate Multi-Engineersynchronous Heterogeneous Cad, Kelly Eric Bowman

Theses and Dissertations

Engineering companies are sociotechnical systems in which engineers, designers, analysts, etc. use an array of software tools to follow prescribed product-development processes. The purpose of these amalgamated systems is to develop new products as quickly as possible while maintaining quality and meeting customer and market demands. Researchers at Brigham Young University have shortened engineering design cycle times through the development and use of multiengineer synchronous (MES) CAD tools. Other research teams have shortened design cycle-times by extending seamless interoperability across heterogeneous design tools and domains. Seamless multi-engineer synchronous heterogeneous (MESH) CAD environments is the focus of this dissertation. An architecture …

An Analysis Of The Effectiveness Of A Multi-Disciplinary Decision Support System On System-Level Decision Making, Troy Mario Seletos

Theses and Dissertations

Decisions Support Systems (DSSs) are used to enhance decision maker speed and effectiveness. However, without a view of an entire system, any decision may have unanticipated effects such as sub-optimal outcomes. The purpose of this research is to show that with a system-level analysis, more informed decisions can be made that take into account a larger system or greater number of dimensions or objectives. This research also explores the benefits of using a DSS over analysis of unprocessed data and the effectiveness of integrating a product design generator (PDG) with a business DSS, creating a system DSS, where system-level effects …

Dynamic Control Of Radiative Surface Properties With Origami-Inspired Design, Rydge B. Mulford, Matthew R. Jones, Brian D. Iverson

Faculty Publications

Thermal management systems for space equipment commonly use static solutions that do not adapt to environmental changes. Dynamic control of radiative surface properties is one way to respond to environmental changes and to increase the capabilities of spacecraft thermal management systems. This paper documents an investigation of the extent to which origami-inspired surfaces may be used to control the apparent absorptivity of a reflective material. Models relating the apparent absorptivity of a radiation shield to time-dependent surface temperatures are presented. Results show that the apparent absorptivity increases with increasing fold density and indicate that origami-inspired designs may be used to …

Associative Cad References In The Neutral Parametric Canonical Form, Daniel Robert Staves

Theses and Dissertations

Due to the multiplicity of computer-aided engineering applications present in industry today, interoperability between programs has become increasingly important. A survey conducted among top engineering companies found that 82% of respondents reported using 3 or more CAD formats during the design process. A 1999 study by the National Institute for Standards and Technology (NIST) estimated that inadequate interoperability between the OEM and its suppliers cost the US automotive industry over $1 billion per year, with the majority spent fixing data after translations. The Neutral Parametric Canonical Form (NPCF) prototype standard developed by the NSF Center for e-Design, BYU Site offers …

Maximizing Virtual Mucax Engineering Design Team Performance, Brett Randall Stone

Theses and Dissertations

Teams of design engineers are increasingly working as members of virtual teams, or teams whose members are distributed geographically and communicate mostly through electronic means. In addition, emerging multi-user (MU) applications engage complementary teams in synchronous design activities. These new MU tools are changing the way engineers work together. Together, these factors have created a new and interesting environment in which engineering design teams must function. The work presented here lays out two major themes that teams and their managers can effectively apply to organizing and managing MU teams: 1) teams can maximize their potential productivity by determining the optimal …

The Bambow: A Bamboo-Cored Carbon-Fiber Composite Bow, Ezekiel G. Merriam

Student Works

Archery is a sport that has benefited from thousands of years of development. Starting with primitive stick-bows, ancient people found they could propel projectiles larger distances and with more effectiveness than by hand or with other mechanical aids. Over the centuries different cultures adopted and advanced different aspects of the technology, including materials, geometry, and manufacturing methods. In the Mechanical Engineering Department at BYU, Nephi's Steel Bow Competition is held annually to challenge engineering students to test their knowledge of mechanics and materials. As a past participant in this competition, I felt building an advanced composite bow would be an …

Wind Plant System Engineering Through Optimization Of Layout And Yaw Control, Paul Fleming, Andrew Ning, Pieter Gebraad, Katherine Dykes

Faculty Publications

Recent research has demonstrated exciting potential for wind plant control systems to improve the cost of energy of wind plants. Wind plant controls seek to improve global wind plant performance over control systems in which each turbine optimizes only its individual performance by accounting for the way wind turbines interact through their wakes. Although these technologies can be applied to existing wind plants, it is probable that the maximum benefit would be derived by designing wind plants with these capabilities in mind. In this paper, we use system engineering approaches to perform coupled wind plant controls and position layout optimizations …

Inversion Characteristics Of A Buoyant Cylindrical Puck During Oblique Water Impact, Zachary Crawford Smith

Theses and Dissertations

The Apollo Command Module had a tendency to flip over upon impact with the ocean surface after returning from space (9/19 times). In an effort to better characterize the inversion process for future water landing vehicles, experimental results for a simplified buoyant cylindrical puck impacting the water surface are presented. This study focuses on the dependence of inversion upon vertical velocity, horizontal velocity, and the pitch angle of the puck relative to the free surface. High-speed images reveal an asymmetric cavity that forms upon water impact. The asymmetric cavity then collapses, applying a moment, which can be sufficient to invert …

Aerodynamic Performance Characterization Of Leading Edge Protrusions On Small Propellers, Kevin Moore, Andrew Ning

Faculty Publications

The relatively large tubercles or protruding bumps on the leading edge of the humpback whale fin create counter-rotating chordwise vortices. At high Reynolds numbers, these vortices have been shown to delay stall with minimal effect on drag. The range of Reynolds numbers that these types of vortices form is unknown, and so an investigation of the potential for an increased envelope of operation for small aircraft propellers was done. For the cases tested in this report no benefits were observed. The addition of leading edge protrusions decreased propeller performance in both efficiency and thrust. Because of the inherent restrictions on …

Parameterized Vertical-Axis Wind Turbine Wake Model Using Cfd Vorticity Data, Andrew Ning, Eric Tingey

Faculty Publications

In order to analyze or optimize a wind farm layout, reduced-order wake models are often used to estimate the interactions between turbines. While many such models exist for horizontal-axis wind turbines, for vertical-axis wind turbines (VAWTs) a simple parametric wake model does not exist. Using computational fluid dynamic (CFD) simulations we computed vorticity in a VAWT wake, and parameterized the data based on normalized downstream positions, tip-speed ratio, and solidity to predict a normalized wake velocity deficit. When compared to CFD, which takes about a day to run one simulation, the reduced-order model predicts the velocity deficit at any location …

Optimization-Based Path Planning For Separation Assurance On Small Unmanned Aircraft, Matthew Duffield, Andrew Ning, Timothy Mclain

Faculty Publications

This paper presents a time-based path planning optimizer for separation assurance for unmanned aircraft systems (UAS). Given Automatic Dependent Surveillance-Broadcast (ADS-B) as a sensor, intruder information such as position, velocity, and identification information is available at ranges on the order of 50 nautical miles. Such long-range intruder detection facilitates path planning for separation assurance, but also poses computational challenges. The time-based path optimizer presented in this paper provides a path-planning method that takes advantage of long-range ADS-B information and addresses the associated challenges. It is capable of long-range path planning and, due to the convex formulation, is computationally efficient enough …

Landing Zone Determination For Autonomous Rotorcraft In Surveillance Applications, Timothy Mclain, Gary J. Ellingson, Justin Mackay

Faculty Publications

This paper presents an approach for finding possible landing sites for a rotorcraft from an inertially referenced point-cloud model of the environment. To identify potential landing sites that are suitably flat and level, a grid-based random sample consensus algorithm separates the terrain map into discrete areas for plane-fitting analysis. Landing sites are selected that satisfy constraints on flatness and levelness while optimizing the surveillance target’s visibility. Flight test results are presented from a small multirotor aircraft flying over a scale-model cityscape. Results from real-time landing-site experiments are presented and discussed.