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Full-Text Articles in Mechanical Engineering

Design And Evaluation Of A Humanoid Robot For Autism Therapy, Daniel J. Ricks Mar 2010

Design And Evaluation Of A Humanoid Robot For Autism Therapy, Daniel J. Ricks

Theses and Dissertations

Recent evidence has shown that children with autism may behave more pro-socially when interacting with a robot than with a human. The objective of this research is to develop a robotic system for use in the clinical treatment of children with autism. The governing assumption behind this thesis is that using a robot in a clinic, under the guidance of a trained therapist, may lead to therapeutic benefits that may not be achieved without the presence of the robot. The robot Troy was developed to fulfill such a role in a clinical setting. The primary objective was to design a …


Bidirectional Electrowetting Actuation With Voltage Polarity Dependence, Nathan B. Crane, Alex A. Volinsky, Pradeep Mishra, Ajay Rajgadkar, Mehdi Khodayari Mar 2010

Bidirectional Electrowetting Actuation With Voltage Polarity Dependence, Nathan B. Crane, Alex A. Volinsky, Pradeep Mishra, Ajay Rajgadkar, Mehdi Khodayari

Faculty Publications

This work presents an electrowetting system in which the actuation direction depends on the polarity of the applied voltage. Since electrowetting response depends on the voltage squared, it is typically independent of voltage sign to first order. However, the introduction of an electrochemicaal diode into the equivalent electrical circuit permits polarity-dependent behavior. Electrochemical diodes were created by making holes in the dielectric. The aluminum electrodes passivate and prevent current flow in one direction, creating diode-like behavior with high breakdown voltage. The resulting actuation forces were directly measured and are of comparable magnitude for both actuation directions.


Note: Thermal Analog To Atomic Force Microscopy Force-Displacement Measurements For Nanoscale Interfacial Contact Resistance, Brian D. Iverson, John E. Blendell, Suresh V. Garimella Mar 2010

Note: Thermal Analog To Atomic Force Microscopy Force-Displacement Measurements For Nanoscale Interfacial Contact Resistance, Brian D. Iverson, John E. Blendell, Suresh V. Garimella

Faculty Publications

Thermal diffusion measurements on polymethylmethacrylate-coated Si substrates using heated atomic force microscopy tips were performed to determine the contact resistance between an organic thin film and Si. The measurement methodology presented demonstrates how the thermal contrast signal obtained during a force-displacement ramp is used to quantify the resistance to heat transfer through an internal interface. The results also delineate the interrogation thickness beyond which thermal diffusion in the organic thin film is not affected appreciably by the underlying substrate.


Multidisciplinary Considerations In The Design Of Wings And Wing Tip Devices, Andrew Ning, Ilan Kroo Mar 2010

Multidisciplinary Considerations In The Design Of Wings And Wing Tip Devices, Andrew Ning, Ilan Kroo

Faculty Publications

Conceptual wing design analysis methods are combined with numerical optimization to find minimum drag wings subject to constraints on lift, weight, pitching moment, and stall speed. Tip extensions and winglets designed for minimum drag achieve similar performance, with the optimal solution depending on the ratio of the maneuver lift coecient to the cruise lift coecient. The results highlight the importance of accounting for the depth of the wing structural box in the weight model, and including constraints on stall speed. For tailless aircraft, C-wings show a slight performance advantage over wings with winglets when longitudinal trim and stability constraints are …


Characterization Of Electrowetting Processes Through Force Measurements, Nathan B. Crane, Pradeep Mishra, Alex A. Volinsky Jan 2010

Characterization Of Electrowetting Processes Through Force Measurements, Nathan B. Crane, Pradeep Mishra, Alex A. Volinsky

Faculty Publications

A new method of characterizing electrowetting is presented in which the forces applied to a modified nanoindenter tip by a test water droplet are measured. A droplet is trapped between the flat nanoindenter tip and the test substrate containing the necessary electrodes. When voltage is applied to the electrodes in the substrate, lateral and normal forces are exerted on the tip and measured by the nanoindenter transducer. Proper selection of the tip geometry permits direct prediction of the resulting in-plane lateral forces using analytical formulas derived from the Young-Lippmann equation. Experimental results show good agreement with both analytical and numerical …


Thermal Analog To Afm Force-Displacement Measurements For Nanoscale Interfacial Contact Resistance, Brian D. Iverson, John E. Blendell, Suresh V. Garimella Jan 2010

Thermal Analog To Afm Force-Displacement Measurements For Nanoscale Interfacial Contact Resistance, Brian D. Iverson, John E. Blendell, Suresh V. Garimella

Faculty Publications

Thermal diffusion measurements on PMMA-coated Si substrates using heated AFM tips were performed to determine the contact resistance between an organic thin film and Si. The measurement methodology presented demonstrates how the thermal contrast signal obtained during a force-displacement ramp is used to quantify the resistance to heat transfer through an internal interface. The results also delineate the interrogation thickness beyond which thermal diffusion in the organic thin film is not affected appreciably by the underlying substrate.


Efficient Rotation Algorithms For Texture Evolution, Mark W. Esty Dec 2009

Efficient Rotation Algorithms For Texture Evolution, Mark W. Esty

Theses and Dissertations

Texture evolution is a vital component of many computational tools that link structure, properties and processes of polycrystalline materials. By definition, this evolution process involves the manipulation, via rotation, of points in orientation space. The computational requirements of the current methods being used to rotate crystalline orientations are a significant limiting factor in the drive to merge the texture information of materials into the engineering design process. The goal of this research is to find and implement a practical rotation algorithm that can significantly decrease the computation time required to rotate macroscopic and microscopic crystallographic textures. Three possible algorithms are …


Development Of A Methodology For Numerical Simulation Of A D C Arc Discharge In A Liquid Dielectric, Christopher James Lewis Dec 2009

Development Of A Methodology For Numerical Simulation Of A D C Arc Discharge In A Liquid Dielectric, Christopher James Lewis

Theses and Dissertations

The majority of literature regarding the numerical simulation of arc discharges in gaseous environments has used a plasma physics approach. Virtually all simulations treat the discharge as an idealized gaseous plasma, which can be described by temperature, pressure, and electric field. This approach can work well if the media is a shielding gas such as Argon; however, the approach does not work well for processes such as underwater welding, EDM, and underwater discharges used to generate high purity particles. The reason these discharges do not have many extensive simulation efforts as described in the literature is because they occur in …


Energy Dissipation Caused By Asphalt Roadway Gouges For Use In Accident Reconstruction, Charles L. Crosby Dec 2009

Energy Dissipation Caused By Asphalt Roadway Gouges For Use In Accident Reconstruction, Charles L. Crosby

Theses and Dissertations

In reconstruction of on-roadway vehicle accidents, roadway surface gouges and the forces and energy attributed to the related vehicle components become important keys to resolving an accurate accident reconstruction. These roadway gouge forces vary depending upon such factors as surface temperature and the velocity and geometry of the gouging mechanism. Accounting for the forces applied to vehicle components and the energy dissipated from such forces can be helpful in accident reconstruction where supporting data exists. This research documents the force necessary to create a given roadway gouge geometry. Controlled pavement gouging tests were performed using roadway surface temperature and gouging …


Vision-Based Precision Landings Of A Tailsitter Uav, Paul Travis Millet Nov 2009

Vision-Based Precision Landings Of A Tailsitter Uav, Paul Travis Millet

Theses and Dissertations

We present a method of performing precision landings of a vertical take-off and landing (VTOL) unmanned air vehicle (UAV) with the use of an onboard vision sensor and information about the aircraft's orientation and altitude above ground level (AGL). A method for calculating the 3-dimensional location of the UAV relative to a ground target of interest is presented as well as a navigational controller to position the UAV above the target. A method is also presented to prevent the UAV from moving in a way that will cause the ground target of interest to go out of view of the …


Investigate Correlations Of Microstructures, Mechanical Properties And Fsw Process Variables In Friction Stir Welded High Strength Low Alloy 65 Steel, Lingyun Wei Nov 2009

Investigate Correlations Of Microstructures, Mechanical Properties And Fsw Process Variables In Friction Stir Welded High Strength Low Alloy 65 Steel, Lingyun Wei

Theses and Dissertations

The present study focuses on developing a relationship between process variables, mechanical properties and post weld microstructure in Friction Stir Welded HSLA 65 steel. Fully consolidated welds can be produced in HSLA 65 steel by PCBN Convex-Scrolled-Shoulder-Step-Spiral (CS4) tool over a wide range of parameters. Microstructures in the nugget center (NC) are dominated by lath bainite and a few polygonal/allotriomorphic grain boundary ferrites. FSW dependent variables are related to FSW independent variables by non-linear relationship. Heat input is identified to be the best parameter index to correlate with microstructures. With increasing heat input, the volume of bainite is reduced, the …


Automated Data Import And Revision Management In A Product Lifecycle Management Environment, Brad Walton Brooks Oct 2009

Automated Data Import And Revision Management In A Product Lifecycle Management Environment, Brad Walton Brooks

Theses and Dissertations

A method has been created that addresses the issues that prohibit the conversion of product artifacts into a secure, efficient and reliable Product Lifecycle Management (PLM) environment. These issues include automatic import of data into a PLM system and revision control of such data. A test case is shown which specifically addresses these issues as they pertain to the management of both legacy and new engineering data in a PLM system.


Haptic Collision Avoidance For A Remotely Operated Quadrotor Uav In Indoor Environments, Adam M. Brandt Sep 2009

Haptic Collision Avoidance For A Remotely Operated Quadrotor Uav In Indoor Environments, Adam M. Brandt

Theses and Dissertations

A quadrotor is an omnidirectional unmanned air vehicle that is suitable for indoor flight because of its ability to hover and maneuver in confined spaces. The remote operation of this type of vehicle is difficult due to a lack of sensory perception; typically, the view from the onboard camera is the only information transmitted to the pilot. This thesis proposes using force feedback exerted by the command input device on the hand of the pilot to assist in avoiding collisions while navigating in indoor environments. Five candidate algorithms are presented for calculating the forces to be felt by the pilot …


Performance Flight Testing Of Small Electric Powered Unmanned Aerial Vehicles, Jon N. Ostler, W. Jerry Bowman, Deryl O. Snyder, Timothy W. Mclain Sep 2009

Performance Flight Testing Of Small Electric Powered Unmanned Aerial Vehicles, Jon N. Ostler, W. Jerry Bowman, Deryl O. Snyder, Timothy W. Mclain

Faculty Publications

Flight testing methods are developed to find the drag polar for small unmanned aerial vehicles powered by electric motors with fixed-pitch propellers. Wind tunnel testing was used to characterize the propeller-motor efficiency. The drag polar was constructed using data from flight tests. This drag polar was then used to find the following performance parameters: maximum velocity, minimum velocity, velocity for maximum range, velocity for maximum endurance, maximum rate of climb, maximum climb angle, minimum turn radius, maximum turn rate, and maximum bank angle. The developed flight testing methods are used to characterize the performance of a small UAV.


Numerical Characterizaton Of The Inlet Flow In Eleven Radial Flow Turbomachines, Nathan O. Packard Aug 2009

Numerical Characterizaton Of The Inlet Flow In Eleven Radial Flow Turbomachines, Nathan O. Packard

Theses and Dissertations

Statistics based models have been developed previously to predict a priori the performance of new radial flow compressors and pumps and to model test data of previously designed and tested machines. Unfortunately, critical dynamics in the inlet region of the machines were neglected. Consequently, room for improvement in the previous modeling exists. Historical practice has placed a static pressure tap on the shroud just upstream of the impeller leading edge for experimental characterization. The previously developed statistics based models rely on this measured data. However, the location of the tap may be vulnerable to high gradients which would decrease the …


Analysis Of Induced Vibrations In Fully-Developed Turbulent Pipe Flow Using A Coupled Les And Fea Approach, Thomas P. Shurtz Aug 2009

Analysis Of Induced Vibrations In Fully-Developed Turbulent Pipe Flow Using A Coupled Les And Fea Approach, Thomas P. Shurtz

Theses and Dissertations

Turbulent flow induced pipe vibration is a phenomenon that has been observed but not fully characterized. This thesis presents research involving numerical simulations that have been used to characterize pipe vibration resulting from fully developed turbulent flow. The vibration levels as indicated by: pipe surface displacement, velocity, and acceleration are characterized in terms of the parameters that exert influence. The influences of geometric and material properties of the pipe are investigated for pipe thickness in the range 1 to 8 mm at a diameter of 0.1015 m. The effects of pipe elastic modulus are explored from 3 to 200 GPa. …


Piezoresistive Models For Polysilicon With Bending Or Torsional Loads, Gerrit T. Larsen Aug 2009

Piezoresistive Models For Polysilicon With Bending Or Torsional Loads, Gerrit T. Larsen

Theses and Dissertations

This thesis presents new models for determining piezoresistive response in long, thin polysilicon beams with either axial and bending moment inducing loads or torsional loads. Microelectromechanical (MEMS) test devices and calibration methods for finding the piezoresistive coefficients are also presented for both loading conditions. For axial and bending moment inducing loads, if the piezoresistive coefficients are known, the Improved Piezoresistive Flexure Model (IPFM) is used to find the new resistance of a beam under stress. The IPFM first discretizes the beam into small volumes represented by resistors. The stress that each of these volumes experiences is calculated, and the stress …


Experimental Characterization Of Flow Induced Vibration In Turbulent Pipe Flow, Andrew S. Thompson Aug 2009

Experimental Characterization Of Flow Induced Vibration In Turbulent Pipe Flow, Andrew S. Thompson

Theses and Dissertations

This thesis presents results of an experimental investigation that characterizes the wall vibration of a pipe with turbulent flow passing through it. Specifically, experiments were conducted using a water flow loop to address three general phenomena. The topics of investigation were: 1) How does the pipe wall vibration depend on the average flow speed, pipe diameter, and pipe thickness for an unsupported pipe? 2) How does the behavior change if the pipe is clamp supported at various clamping lengths? 3) What influence does turbulence generation caused by holed baffle plates exert on the pipe response? A single pipe material (PVC) …


Off-Axis Stiffness And Piezroresistive Sensing In Large-Displacement Linear-Motion Microelectromechanical Systems, David G. Smith Aug 2009

Off-Axis Stiffness And Piezroresistive Sensing In Large-Displacement Linear-Motion Microelectromechanical Systems, David G. Smith

Theses and Dissertations

Proper positioning of Microelectromechanical Systems (MEMS) components influences the functionality of the device, especially in devices where the motion is in the range of hundreds of micrometers. There are two main obstacles to positioning: off-axis displacement, and position determination. This work studies four large-displacement devices, their axial and transverse stiffness, and piezoresistive response. Methods for improving the device characteristics are described. The folded-beam suspension, small X-Bob, large X-Bob and double X-Bob were characterized using non-dimensional metrics that measure the displacement with regard to the size of the device, and transverse stiffness with regard to axial stiffness. The stiffness in each …


Radiation And Convection Heat Transfer In Wildland Fire Environments, David J. Frankman Jul 2009

Radiation And Convection Heat Transfer In Wildland Fire Environments, David J. Frankman

Theses and Dissertations

Wildland fire research has been extensive and on going since before 1950. The motivation behind this research is to prevent loss of property and lives. In spite of this research, the heat transfer of fuel ignition and flame spread is not well understood. This dissertation seeks to fill gaps in this understanding through modeling and also by experimentation. The effect of water vapor on the transmission of thermal radiation from the flame to the fuel was investigated. The Spectral Line Weighted-sum-of-gray-gases approach was adopted for treating the spectral nature of the radiation. The study reveals that water vapor has only …


A Methodology For Designing Product Components With Built-In Barriers To Reverse Engineering, Stephen P. Harston Jul 2009

A Methodology For Designing Product Components With Built-In Barriers To Reverse Engineering, Stephen P. Harston

Theses and Dissertations

Reverse engineering, defined as extracting information about a product from the product itself, is a common industry practice for gaining insight into innovative products. Both the original designer and those reverse engineering the original design can benefit from estimating the time and barrier to reverse engineer a product. This thesis presents a set of metrics and parameters that can be used to calculate the barrier to reverse engineer any product as well as the time required to do so. To the original designer, these numerical representations of the barrier and time can be used to strategically identify and improve product …


A Method For Making In Situ Emittance Measurements Of Coal Ash Deposits, Travis J. Moore Jul 2009

A Method For Making In Situ Emittance Measurements Of Coal Ash Deposits, Travis J. Moore

Theses and Dissertations

A major problem associated with any power generation process in which coal is burned is the formation of ash and slag from the inorganic constituents of the coal. Ash deposition on heat transfer surfaces in coal-fired reactors is unavoidable and can have a significant effect on the performance and maintenance of boilers and gasifiers. A greater understanding of the thermal properties of coal ash deposits is important in reducing their negative impact. This work presents the development of an experimental method for making in situ measurements of the spectral emittance of coal ash deposits. It also provides measured emittances for …


Characterizing Material Property Tradeoffs Of Polycrystalline Diamond For Design Evaluation And Selection, Neil David Haddock Jul 2009

Characterizing Material Property Tradeoffs Of Polycrystalline Diamond For Design Evaluation And Selection, Neil David Haddock

Theses and Dissertations

Polycrystalline diamond (PCD) is used as a cutting tool in many industries because of its superior wear resistance compared to single crystal diamond. Engineers who design new PCD materials must have an understanding of the tradeoffs between material properties in order to tailor a product for different applications. Two competing material properties that are often encountered in PCD are transverse rupture strength and thermal-resistance. Thermal-resistance is directly related to the cobalt content of PCD, and is the ability of the material to withstand thermally induced degradation. In this thesis, we characterize the tradeoff boundary between transverse rupture strength and cobalt …


Lamina Emergent Torsion (Let) Joint, Joseph O. Jacobsen, Guimin Chen, Larry L. Howell, Spencer P. Magleby Jul 2009

Lamina Emergent Torsion (Let) Joint, Joseph O. Jacobsen, Guimin Chen, Larry L. Howell, Spencer P. Magleby

Faculty Publications

Part of the challenge in designing compliant mechanisms is finding suitable joints that provide the needed motion and force-deflection characteristics. The Lamina Emergent Torsional (LET) Joint is presented as a compliant joint suited for applications where large angular rotation is desired, but high off-axis stiffness is not as critical. The joint is introduced and the equations necessary for determining the force-deflection characteristics are presented. Since the LET Joint can be fabricated from a single planar layer, it is well suited for macro and micro applications. Illustrative examples are provided with devices fabricated from materials as diverse as steel, polypropylene, and …


Development Of Methods To Propagate Energy Density And Predict Farfield Directivity Using Nearfield Acoustic Holography, Scott Richard Woolston Jul 2009

Development Of Methods To Propagate Energy Density And Predict Farfield Directivity Using Nearfield Acoustic Holography, Scott Richard Woolston

Theses and Dissertations

Acoustical-based imaging systems have found merit in determining the behavior of vibrating structures. This thesis focuses on the continued development of the nearfield acoustic holography (NAH) approach. Conventional NAH consists of first measuring the pressure field on a two-dimensional conformal surface and then propagating this data back to the vibrating structure to obtain information about the source, such as the normal velocity distribution. Recent work has been done which incorporates particle velocity information into the traditional NAH measurements to reduce the number of measurements required. This advancement has made NAH a more affordable tool for acoustical imaging and sound field …


Cross-Correlation-Based Texture Analysis Using Kinematically Simulated Ebsd Patterns, Joshua Peter Kacher Jul 2009

Cross-Correlation-Based Texture Analysis Using Kinematically Simulated Ebsd Patterns, Joshua Peter Kacher

Theses and Dissertations

The development and example applications of a new EBSD-based texture analysis system are presented. This new system uses the cross-correlation function to compare two EBSD patterns at a number of corresponding regions in each pattern to calculate the deformation gradient tensor. Bragg's Law-based simulated EBSD patterns are used as reference patterns in the cross-correlation method to enable the measurements of absolute elastic strain and lattice orientation at discrete points in a crystalline sample. The resolution limits of this new method are explored using a variety of computational and physical experiments. The simulated pattern method is estimated to be able to …


Applications Of Variation Analysis Methods To Automotive Mechanisms, Robert C. Leishman Jun 2009

Applications Of Variation Analysis Methods To Automotive Mechanisms, Robert C. Leishman

Theses and Dissertations

Variation analysis, or tolerance analysis as it is sometimes called, is typically used to predict variation in critical dimensions in assemblies by calculating the stack-up of the contributing component variations. It is routinely used in manufacturing and assembly environments with great success. Design engineers are able to account for the small changes in dimensions that naturally occur in manufacturing processes, in equipment, and due to operators and still ensure that the assemblies will meet the design specifications and required assembly performance parameters. Furthermore, geometric variation not only affects critical fits and clearances in static assemblies, it can also cause variation …


Evaluation Of The Benefits Of Oxy-Combustion On Emissions From A Compression Ignition Engine, Thomas A. Salt Jun 2009

Evaluation Of The Benefits Of Oxy-Combustion On Emissions From A Compression Ignition Engine, Thomas A. Salt

Theses and Dissertations

In this research the benefits of applying oxy-combustion in a diesel engine to reduce NOx and particulate emissions were evaluated. The addition of oxygen to the intake in conjunction with exhaust gas recirculation (EGR) was shown to reduce NOx without an increase in particulate. Indicated specific NOx and particulate emissions for oxygen-enhanced EGR (O-EGR) and EGR without oxygen addition (normal or N-EGR) were compared at three engine loads. NOx emissions correlated with flame temperature for both N-EGR and O-EGR but were slightly lower at a given flame temperature for O-EGR. Flame temperature reduction for N-EGR was primarily through dilution of …


Dynamics And Control Of Cable-Drogue System In Aerial Recovery Of Micro Air Vehicles Based On Gauss's Principle, Liang Sun, Randal W. Beard, Mark B. Colton, Timothy W. Mclain Jun 2009

Dynamics And Control Of Cable-Drogue System In Aerial Recovery Of Micro Air Vehicles Based On Gauss's Principle, Liang Sun, Randal W. Beard, Mark B. Colton, Timothy W. Mclain

Faculty Publications

This paper presents a new concept for aerial recovery of Micro Air Vehicles (ARMAVs) using a large mothership and a recovery drogue. The mothership drags a drogue attached to a cable and the drogue is controlled to match the flight patten of the MAV. This paper uses Gauss’s Principle to derive the dynamic model of the cable-drogue systems. A controllable drogue plays a key role in recovering MAVs in windy conditions. We develop a control approach for the drogue using its drag coefficient. Simulation results based on multilink cable-drogue systems present the feasibility of the aerial recovery concept and the …


Frequency Response Of The Skin On The Head And Neck During Production Of Selected Speech Sounds, Jacob B. Munger May 2009

Frequency Response Of The Skin On The Head And Neck During Production Of Selected Speech Sounds, Jacob B. Munger

Theses and Dissertations

Vibration within the vocal tract during speech is transmitted through body tissue to the skin surface and can be used to transmit speech. Achieving quality speech signals using skin vibration is desirable but problematic, primarily due to the different sources of sound during speech. The objective of this study was to characterize the frequency content of speech signals at various locations on the head and neck. Signals were recorded using accelerometers attached to 15 locations on the heads and necks of 14 males and 10 females as well as a microphone to record audible speech. The subjects produced several isolated …