Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Compliant mechanisms (3)
- CFD (2)
- Kalman filter (2)
- Motor control (2)
- Origami (2)
-
- Origami-inspired design (2)
- Particle image velocimetry (2)
- Tailsitter (2)
- Turbomachinery (2)
- Unmanned aircraft (2)
- 3D reconstruction (1)
- Aerodynamics (1)
- Alloying elements (1)
- Amorphous (1)
- Assistive robotics (1)
- Asymmetry (1)
- Attitude control (1)
- Autism (1)
- Automated landing (1)
- Automated nanoinjection system (1)
- BYU (1)
- Biogas (1)
- Biomass (1)
- Bistable mechanism (1)
- Blade Loading (1)
- Carbon nanotube (1)
- Channel (1)
- Classification (1)
- Co-firing (1)
- Coherent structures (1)
Articles 1 - 30 of 34
Full-Text Articles in Mechanical Engineering
A Variable-Stiffness Compliant Mechanism For Stiffness-Controlled Haptic Interfaces, Jeffrey C. Hawks
A Variable-Stiffness Compliant Mechanism For Stiffness-Controlled Haptic Interfaces, Jeffrey C. Hawks
Theses and Dissertations
In this research a variable-stiffness compliant mechanism was developed to generate variable force-displacement profiles at the mechanisms coupler point. The mechanism is based on a compliant Roberts straight-line mechanism, and the stiffness is varied by changing the effective length of the compliant links with an actuated slider. The variable-stiffness mechanism was used in a one-degree-of-freedom haptic interface to demonstrate the effectiveness of varying the stiffness of a compliant mechanism. Unlike traditional haptic interfaces, in which the force is controlled using motors and rigid links, the haptic interface developed in this work displays haptic stiffness via the variable-stiffness compliant mechanism. The …
A Hybrid Method For Sensitivity Optimization With Application To Radio-Frequency Product Design, Abraham Lee
A Hybrid Method For Sensitivity Optimization With Application To Radio-Frequency Product Design, Abraham Lee
Theses and Dissertations
A method for performing robust optimal design that combines the efficiency of experimental designs and the accuracy of nonlinear programming (NLP) has been developed, called Search-and-Zoom. Two case studies from the RF and communications industry, a high-frequency micro-strip band-pass filter (BPF) and a rectangular, directional patch antenna, were used to show that sensitivity optimization could be effectively performed in this industry and to compare the computational efficiency of traditional NLP methods (using fmincon solver in MATLAB R2013a) and they hybrid method Search-and-Zoom. The sensitivity of the BPF's S11 response was reduced from 0.06666 at the (non-robust) nominal optimum to 0.01862 …
Characterization Of Smoothness In Wrist Rotations, Layne Hancock Salmond
Characterization Of Smoothness In Wrist Rotations, Layne Hancock Salmond
Theses and Dissertations
Smoothness is a hallmark of healthy movement and has the potential to be used as a marker of recovery in rehabilitation settings. While much past research has focused on shoulder and elbow movements (reaching), little is known about movements of the wrist despite its importance in everyday life and its impairment in many neurological and biomechanical disorders. Our current lack of knowledge regarding wrist movement prevents us from improving current models, diagnosis, and treatment of wrist disorders. In particular, while movement smoothness is a well-known characteristic of reaching movements and may potentially be used to diagnose and monitor recovery from …
Modeling And Testing Of Bistable Waterbomb Base Configurations, Brandon Holbrook Hanna
Modeling And Testing Of Bistable Waterbomb Base Configurations, Brandon Holbrook Hanna
Theses and Dissertations
Origami is making an impact in engineering as solutions to problems are being found by applying origami principles (eg. flat-foldability) and using specific crease patterns as inspiration. This thesis presents an in-depth analysis of a particular origami fold -- the waterbomb base -- to facilitate its use in future engineering problems. The watebomb base is of interest due to its familiarity to the origami community, simple topology (can be made by folding a single sheet of paper four times), scalability, generalizability, and interesting kinetic behavior. It can behave as a nonlinear spring as well as a one- or two-way bistable …
Investigating The Relationship Between High Temperature Flow Stress And Friction Stir Weldability In Hsla Steels, David Jordan Walser
Investigating The Relationship Between High Temperature Flow Stress And Friction Stir Weldability In Hsla Steels, David Jordan Walser
Theses and Dissertations
The feed rate at which a defect free friction stir weld can be run (friction stir weldability) on an HSLA steel plate can vary widely between heats that meet the same specified physical properties. Consequently, every time a new heat of HSLA steel is obtained, exploratory welds must be run to determine the proper feed rate for that plate. Previous research suggests that the varying levels of alloying elements related to high temperature physical properties between the different heats causes the observed change in friction stir weldability. Because of this, it was hypothesized that the high temperature physical properties of …
Light Field Imaging Applied To Reacting And Microscopic Flows, Jonathon Remy Pendlebury
Light Field Imaging Applied To Reacting And Microscopic Flows, Jonathon Remy Pendlebury
Theses and Dissertations
Light field imaging, specifically synthetic aperture (SA) refocusing is a method used to combine images from an array of cameras to generate a single image with a narrow depth of field that can be positioned arbitrarily throughout the volume under investigation. Creating a stack of narrow depth of field images at varying locations generates a focal stack that can be used to find the location of objects in three dimensions. SA refocusing is particularly useful when reconstructing particle fields that are then used to determine the movement of the fluid they are entrained in, and it can also be used …
Fault Detection For Unmanned Aerial Vehicles With Non-Redundant Sensors, Brandon Jeffrey Cannon
Fault Detection For Unmanned Aerial Vehicles With Non-Redundant Sensors, Brandon Jeffrey Cannon
Theses and Dissertations
To operate, autonomous systems of necessity employ a variety of sensors to perceive their environment. Many small unmanned aerial vehicles (UAV) are unable to carry redundant sensors due to size, weight, and power (SWaP) constraints. Faults in these sensors can cause undesired behavior, including system instability. Thus, detection of faults in these non-redundant sensors is of paramount importance.The problem of detecting sensor faults in non-redundant sensors on board autonomous aircraft is non-trivial. Factors that make development of a solution difficult include both an inability to perfectly characterize systems and sensors as well as the SWaP constraints inherent with small UAV. …
Compliant Mechanisms For Deployable Space Systems, Shannon Alisa Zirbel
Compliant Mechanisms For Deployable Space Systems, Shannon Alisa Zirbel
Theses and Dissertations
The purpose of this research is to develop fundamentals of compliant mechanisms in deployable space systems. The scope was limited to creating methods for thick origami, developing compliant deployable solar arrays, and developing methods for stowing and deploying the arrays. The research on actuation methods was focused on a one-time deployment of the array. Concepts for both passive and active actuation were considered. The primary objective of this work was to develop approaches to accommodate thickness in origami-based deployable arrays with a high ratio of deployed-to-stowed diameter. The HanaFlex design was derived from the origami flasher model and is developed …
Design Considerations In The Development And Actuation Of Origami-Based Mechanisms, Eric W. Wilcox
Design Considerations In The Development And Actuation Of Origami-Based Mechanisms, Eric W. Wilcox
Theses and Dissertations
Origami-based mechanisms have unique characteristics that make them attractive for engineering applications. However, origami-based design is still a developing area of design. Continued work to increase general understanding of key design parameters specific to origami-based mechanisms will increase the ability of designers to capture the potential benefits of origami-based mechanisms. This thesis presents a fundamental study of origami to assist designers in gaining a stronger understanding of the key parameters and capabilities of origami-based mechanisms. As a starting point a study of fundamental motions in action origami models (those that exhibit motions in their folded state) is presented to explore …
Design And Analysis Of Robotically-Controlled Minimally Invasive Surgical Instruments, Jordan D. Tanner
Design And Analysis Of Robotically-Controlled Minimally Invasive Surgical Instruments, Jordan D. Tanner
Theses and Dissertations
Robot-assisted minimally invasive surgery is used to perform intricate surgical tasks through small incisions using long, slender instruments. The miniaturization of these instruments is advantageous to both surgeon and patient because smaller instruments reduce trauma to surrounding tissue, decrease patient recovery times, and can be used in confined spaces otherwise inaccessible using larger instruments. However, miniaturization of existing designs is limited by friction between moving parts, the volume occupied by the end effector, and manufacturing and assembly constraints. The objective of this work is to develop and analyze concepts that can be used in robot-assisted needlescopic surgery. The concepts are …
Application Of Variation Of Parameters To Solve Nonlinear Multimode Heat Transfer Problems, Travis J. Moore
Application Of Variation Of Parameters To Solve Nonlinear Multimode Heat Transfer Problems, Travis J. Moore
Theses and Dissertations
The objective of this work is to apply the method of variation of parameters to various direct and inverse nonlinear, multimode heat transfer problems. An overview of the general method of variation of parameters is presented and applied to a simple example problem. The method is then used to obtain solutions to three specific extended surface heat transfer problems: 1. a radiating annular fin, 2. convective and radiative exchange between the surface of a continuously moving strip and its surroundings, and 3. convection from a fin with temperature-dependent thermal conductivity and variable cross-sectional area. The results for each of these …
Characterization Of Postural Tremor In Essential Tremor Using A Seven-Degree-Of-Freedom Model, Daniel William Geiger
Characterization Of Postural Tremor In Essential Tremor Using A Seven-Degree-Of-Freedom Model, Daniel William Geiger
Theses and Dissertations
Essential Tremor (ET), a condition characterized by postural and kinetic tremor in the upper limbs, is one of the most prevalent movement disorders. While pharmaceutical and surgical treatment options exist, they are not ideal. Assistive devices have the potential to provide relief to patients but are largely unexplored for ET. Furthermore, prior characterizations of essential tremor have focused on endpoint tremor and provide insufficient detail for designing such a device. We propose and demonstrate a novel method for characterizing essential tremor in the 7 proximal degrees of freedom (DOF) of the upper limb in various postures. In addition, we provide …
Co-Firing Biomass With Biogas In Cookstoves With A Fan, Manil Poudyal
Co-Firing Biomass With Biogas In Cookstoves With A Fan, Manil Poudyal
Theses and Dissertations
Co-firing is a combustion process in which more than one type of fuel is used. In many cases, co-firing reduces fuel costs and/or reduces the environmental impact. The objective of this research was to test the hypothesis that adding biogas to be co-fired with biomass in a traditional cookstove reduces indoor air pollution and increases the combustion efficiency. The impact of co-firing on indoor air pollution is assessed by comparing the concentrations of carbon monoxide and particulate matter in the exhaust stream of a co-fired cookstove to a cookstove fueled with biomass alone. The concentrations of each of these pollutants …
Piv Measurements Of Turbulent Flow In A Rectangular Channel Over Superhydrophobic Surfaces With Riblets, Richard Mark Perkins
Piv Measurements Of Turbulent Flow In A Rectangular Channel Over Superhydrophobic Surfaces With Riblets, Richard Mark Perkins
Theses and Dissertations
In this thesis I investigate characteristics of turbulent flow in a channel where one of the walls has riblets, superhydrophobic microribs, or a hybrid surface with traditional riblets built on a superhydrophobic microrib surface. PIV measurements are used to find the velocity profile, the turbulent statistics, and shear stress profile in the rectangular channel with one wall having a structured test surface. Both riblets and superhydrophobic surfaces can each provide a reduction in the wall shear stress in a turbulent channel flow. Characterizing the features of the flow using particle image velocimetry (PIV) is the focus of this research. Superhydrophobicity …
Compliant Joints Suitable For Use As Surrogate Folds, Isaac L. Delimont
Compliant Joints Suitable For Use As Surrogate Folds, Isaac L. Delimont
Theses and Dissertations
Origami-inspired design is an emerging field capable of producing compact and efficient designs. The object of a surrogate fold is to provide a fold-like motion in a non-paper material without undergoing yielding. Compliant mechanisms provide a means to achieve these objectives as large deflections are achieved. The purpose of this thesis is to present a summary of existing compliant joints suitable for use as surrogate folds. In doing so, motions are characterized which no existing compliant joint provides. A series of compliant joints is proposed which provides many of these motions. The possibility of patterning compliant joints to form an …
System Identification Of An Unmanned Tailsitter Aircraft, Nathan W. Edwards
System Identification Of An Unmanned Tailsitter Aircraft, Nathan W. Edwards
Theses and Dissertations
The motivation for this research is the need to improve performance of the autonomous flight of a tailsitter UAV. Tailsitter aircraft combine the hovering and vertical take-off and landing capability of a rotorcraft with the long endurance flight capability of a fixed-wing aircraft. The particular aircraft used in this research is the V-Bat, a tailsitter UAV with a conventional wing and the propeller and control surfaces located within a ducted-fan tail assembly. This research focuses on identifying the models and parameters of the V-Bat in hover and level flight as a basis for the design of the control systems for …
Conflict Management And Model Consistency In Multi-User Cad, Ammon Ikaika Hepworth
Conflict Management And Model Consistency In Multi-User Cad, Ammon Ikaika Hepworth
Theses and Dissertations
The NSF Center for e-Design, Brigham Young University (BYU) site has re-architected Computer Aided Design (CAD) tools, enabling multiple users to concurrently create, modify and view the same CAD part or assembly. This technology allows engineers, designers and manufacturing personnel to simultaneously contribute to the design of a part or assembly in real time,enabling parallel work environments within the CAD system. Multi-user systems are only as robust and efficient as their methods for managing conflicts and preserving model consistency. Conflicts occur in multi-user CAD when multiple users interoperate with the same or dependent geometry. Some conflicts can lead to model …
Refinement And Characterization Of Synthetic Vocal Fold Models, Shelby Charisse Ward
Refinement And Characterization Of Synthetic Vocal Fold Models, Shelby Charisse Ward
Theses and Dissertations
Understanding vocal fold mechanics is an integral part of voice research and synthetic vocal fold models are an essential tool in characterizing vocal fold mechanics. These models contain multiple layers with varying stiffness, much like human vocal folds. The purpose of this thesis is to improve the current models and modeling techniques, as well as investigate the impact of asymmetry on model vibration. A new design for an MRI-based model is detailed. This model has a more realistic geometry than the simplified models and mimics some of the vibratory characteristics observed in human vocal folds. The MRI-based model was used …
Elastic Energy Absorption Via Compliant Corrugations, Sean S. Tolman
Elastic Energy Absorption Via Compliant Corrugations, Sean S. Tolman
Theses and Dissertations
Elastic absorption of kinetic energy and distribution of impact forces are required in many applications. This may be achieved through the use of compliant corrugations. An innovative padding concept is investigated for such applications. Also, recent attention given to the potential for using origami in engineering applications may provide new corrugation configurations that are advantageous for energy absorption and force distribution. This work explores three areas related to these concepts.First, the parameters of a compliant, corrugated padding concept are investigated using Finite Element Analyses (FEA) and physical testing. The shape of the corrugation cross section is explored as well as …
Development Of A Complex Synthetic Larynx Model And Characterization Of The Supraglottal Jet, Jayrin Ella Seegmiller
Development Of A Complex Synthetic Larynx Model And Characterization Of The Supraglottal Jet, Jayrin Ella Seegmiller
Theses and Dissertations
Voice is an important tool for communication. Consequently, voice disorders tend to severely diminish quality of life. Voice research seeks to understand the physics that govern voice production to improve treatment of voice disorders. This thesis develops a method for creating complex synthetic laryngeal models and obtaining flow data within these complex models. The method uses Computed Tomography (CT) scan data to create silicone models of the larynx. Index of refraction matching allows flow field data to be collected within a synthetic complex larynx, which had previously been impossible. A short proof-of-concept of the method is set forth. Details on …
Automated Landing Site Determination For Unmanned Rotocraft Surveillance Applications, Justin Keith Mackay
Automated Landing Site Determination For Unmanned Rotocraft Surveillance Applications, Justin Keith Mackay
Theses and Dissertations
Unmanned air vehicles have been increasing in their autonomous capabilities. This research furthers these capabilities by focusing on the automation of landing site determination for rotorcraft in urban environments. Automated landing saves energy and allows the aircraft to choose areas that are safe for people and the aircraft. Two methods are used to gather information about the terrain of potential landing sites. One method is 3D reconstruction from multiple camera images. The other method uses a range sensor to reconstruct the terrain. Both of these methods create an inertial terrain map of the environment in the form of a point …
Articulated Spine For A Robot To Assist Children With Autism, Brandon M. Norton
Articulated Spine For A Robot To Assist Children With Autism, Brandon M. Norton
Theses and Dissertations
Autism spectrum disorder (ASD) affects about 1.5 million individuals in the US alone. The consequences of ASD affect families, caregivers, and social structures. This thesis adds to a growing group of people performing research on mitigating the effects of autism through robotics. Children with ASD tend to interact with robots more easily than with other humans. The goal of robotic therapy is not to help children interact with robots, but to generalize the behavior to humans. An articulated spine is a key to human emotional expression through shaping, weight shifting, and flow. Despite this importance, this feature is all but …
A Computational Hybrid Method For Self-Intersection Free Offsetting Of Cad Geometry, Garrett Clark Bodily
A Computational Hybrid Method For Self-Intersection Free Offsetting Of Cad Geometry, Garrett Clark Bodily
Theses and Dissertations
Surface offsetting is a valuable tool used in Computer Aided Design (CAD). An offset surface is a collection of points that are at a constant distance from another surface. An offset surface is created in CAD by selecting a surface and then specifying the distance that the surface is to be offset. If a surface is selected and a distance of D is specified, then the resulting offset surface should always be distance D from the original surface. The surface offset tool can be used for many applications. Modeling of composites or other layered manufacturing processes rely heavily on offset …
Analysis And Compression Of Large Cfd Data Sets Using Proper Orthogonal Decomposition, Trevor Jon Blanc
Analysis And Compression Of Large Cfd Data Sets Using Proper Orthogonal Decomposition, Trevor Jon Blanc
Theses and Dissertations
Efficient analysis and storage of data is an integral but often challenging task when working with computation fluid dynamics mainly due to the amount of data it can output. Methods centered around the proper orthogonal decomposition were used to analyze, compress, and model various simulation cases. Two different high-fidelity, time-accurate turbomachinery simulations were investigated to show various applications of the analysis techniques. The first turbomachinery example was used to illustrate the extraction of turbulent coherent structures such as traversing shocks, vortex shedding, and wake variation from deswirler and rotor blade passages. Using only the most dominant modes, flow fields were …
Characterization And Optimization Of Thermal Protective Fabrics Designed To Protect Against Splash Hazards, Jeremy Osguthorpe
Characterization And Optimization Of Thermal Protective Fabrics Designed To Protect Against Splash Hazards, Jeremy Osguthorpe
Theses and Dissertations
Thermal textiles used in Personal Protective Equipment (PPE) are used to protect individuals from the hazards of thermal energy. An analytical model of the diffusion of thermal energy within the fabric was developed to simulate the transfer of thermal energy due to a hot liquid splash. Based on the model results, it was determined that that the use of an orthotropic material in which the thermal conductivities in the radial and axial directions are different can be used to decrease the amount of heat transferred through the fabric and thereby increase amount of protection in PPE. An orthotropic material particularly …
Microstructural Factors Of Strain Delocalization In Model Metallic Glass Matrix Composites, Thomas James Hardin
Microstructural Factors Of Strain Delocalization In Model Metallic Glass Matrix Composites, Thomas James Hardin
Theses and Dissertations
Metallic glass matrix composites have enormous potential stemming from the interplay between crystalline and amorphous phases. This work models such a composite using shear transformation zone dynamics (a modified kinetic Monte Carlo method) for the amorphous phase, and a local Taylor dislocation model for the crystalline phase. An N-factorial experiment using the model is presented examining the effects of crystalline volume fraction, microstructure length scale, and yield stress of the crystalline phase. Each replicate is analyzed for maximum stress, maximum strain, strain energy dissipation, strain localization, and strain partitioning between phases. Regression analysis is used to identify statistically-significant trends in …
Validation Of A Modified Version Of Overflow 2.2 For Use With Turbomachinery Under Clean And Total Pressure Distorted Conditions And A Study Of Blade Loading In Distortion, Matthew L. Marshall
Validation Of A Modified Version Of Overflow 2.2 For Use With Turbomachinery Under Clean And Total Pressure Distorted Conditions And A Study Of Blade Loading In Distortion, Matthew L. Marshall
Theses and Dissertations
Inlet distortion is an important consideration in fan performance. Distortion can be generated through flight conditions and airframe-engine interfaces. The focus of this paper is a series of high-fidelity, time-accurate Computational Fluid Dynamics (CFD) simulations of a multistage fan, investigating distortion transfer, distortion generation, and the underlying flow physics under different operating conditions. The simulations are full annulus and include 3 stages and the inlet guide vane (IGV). The code used to carry out these simulations is a modified version of Overflow2.2 that was developed as part of the Computational Research and Engineering Acquisition Tools and Environment (CREATE) program. The …
High Fidelity Time Accurate Cfd Analysis Of A Multi-Stage Turbofan At Various Operating Points In Distorted Inflow, David Bruce Weston
High Fidelity Time Accurate Cfd Analysis Of A Multi-Stage Turbofan At Various Operating Points In Distorted Inflow, David Bruce Weston
Theses and Dissertations
Inlet distortion is an important consideration in fan performance. Distortion can be caused through flight conditions and airframe-engine interfaces. The focus of this paper is a series of high-fidelity time accurate Computational Fluid Dynamics (CFD) simulations of a multistage fan. These investigate distortion transfer and generation as well as the underlying flow physics of these phenomena under different operating conditions. The simulations are performed on the full annulus of a 3 stage fan. The code used to carry out these simulations is a modified version of OVERFLOW 2.2 developed as part of the Computational Research and Engineering Acquisition Tools and …
Aerodynamic Improvements For Auto-Carrying Railcars, Robert Arthur Condie
Aerodynamic Improvements For Auto-Carrying Railcars, Robert Arthur Condie
Theses and Dissertations
The railroad industry is responsible for the mass transport of a vast numbers of goods throughout the United States. As needs and capabilities of the railroad industry have changed, the interest in reducing the resistance of locomotives and railcars has increased. This has become paramount as fuel prices have increased in recent years. Resistant forces can result from friction in mechanical components and aerodynamic drag of the moving train. As the average traveling speeds of trains have increased, aerodynamics are contributing a larger fraction of the overall resistance. For this reason, the aerodynamic profiles of trains have become a topic …
Design And Experimental Testing Of Nanoinjection Protocols For Delivering Molecules Into Hela Cells With A Bio-Mems Device, Zachary Kendall Lindstrom
Design And Experimental Testing Of Nanoinjection Protocols For Delivering Molecules Into Hela Cells With A Bio-Mems Device, Zachary Kendall Lindstrom
Theses and Dissertations
Delivering foreign molecules into living cells is a broad and ongoing area of research. Gene therapy, or delivering nucleic acids into cells via non-viral or viral pathways, is an especially promising area for pharmaceutics. All gene therapy methods have their respective advantages and disadvantages, including limited delivery efficiency and low viability. Nanoinjection, or delivering molecules into cells using a solid lance, has proven to be highly efficient while maintaining high viability levels. In this thesis, an array of solid silicon lances was tested by nanoinjecting tens of thousands of HeLa cancer cells simultaneously. Several molecule types were injected in different …