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2011

Iowa State University

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Full-Text Articles in Mechanical Engineering

Aptamer Functionalized Microcantilever Sensors For Cocaine Detection, Kyungho Kang, Ashish Sachan, Marit Nilsen-Hamilton, Pranav Shrotriya Dec 2011

Aptamer Functionalized Microcantilever Sensors For Cocaine Detection, Kyungho Kang, Ashish Sachan, Marit Nilsen-Hamilton, Pranav Shrotriya

Mechanical Engineering Publications

A cocaine-specific aptamer was used as a receptor molecule in a microcantilever-based surface stress sensor for detection of cocaine molecules. An interferometric technique that relies on measuring differential displacement between two microcantilevers (a sensing/reference pair) was utilized to measure the cocaine/aptamer binding induced surface stress changes. Sensing experiments were performed for different concentrations of cocaine from 25 to 500 μM in order to determine the sensor response as a function of cocaine concentration. In the lower concentration range from 25 to 100 μM, surface stress values increased proportionally to coverage of aptamer/cocaine complexes from 11 to 26 ...


Three-Dimensional Profilometry With Nearly Focused Binary Phase-Shifting Algorithms, Laura D. Ekstrand, Song Zhang Dec 2011

Three-Dimensional Profilometry With Nearly Focused Binary Phase-Shifting Algorithms, Laura D. Ekstrand, Song Zhang

Mechanical Engineering Publications

This Letter investigates the effects of different phase-shifting algorithms on the quality of high-resolution three-dimensional (3-D) profilometry produced with nearly focused binary patterns. From theoretical analyses, simulations, and experiments, we found that the nine-step phase-shifting algorithm produces accurate 3-D measurements at high speed without the limited depth range and calibration difficulties that typically plague binary defocusing methods. We also found that the use of more fringe patterns does not necessarily enhance measurement quality.


Experimental Study Of High-Frequency Vibration Assisted Micro/Mesoscale Forming Of Metallic Materials, Zhehe Yao, Gap-Yong Kim, Leann E. Faidley, Qingze Zou, Deqing Mei, Zichen Chen Dec 2011

Experimental Study Of High-Frequency Vibration Assisted Micro/Mesoscale Forming Of Metallic Materials, Zhehe Yao, Gap-Yong Kim, Leann E. Faidley, Qingze Zou, Deqing Mei, Zichen Chen

Mechanical Engineering Publications

Micro/mesoscale forming is a promising technology for mass production of miniature metallic parts. However, fabrication of micro/mesoscale features leads to challenges due to the friction increase at the interface and tool wear from highly localized stress. In this study, the use of high-frequency vibration for potential application in micro/mesoscale forming has been investigated. A versatile experimental setup based on a magnetostrictive (Terfenol-D) actuator was built. Vibration assisted micro/mesoscale upsetting, pin extrusion and cup extrusion were conducted to understand the effects of workpiece size, excitation frequency, and the contact condition. Results showed a change in load reduction ...


Autoexposure For Three-Dimensional Shape Measurement Using A Digital-Light-Processing Projector, Laura Ekstrand, Song Zhang Nov 2011

Autoexposure For Three-Dimensional Shape Measurement Using A Digital-Light-Processing Projector, Laura Ekstrand, Song Zhang

Mechanical Engineering Publications

Automatically adapting the camera exposure time is crucial for industrial applications where minimum human intervention is usually desirable. However, it is very challenging to realize such a capability for a conventional fringe projection system where only a finite increment of the exposure time is allowed due to its digital fringe generation nature. We study the generation of sinusoidal fringe patterns by properly defocusing binary ones, which permits the use of an arbitrary exposure time. This provides the potential to adapt the exposure time automatically. We present the principle of an automatic exposure technique and show some experimental results.


Thermal Comparison Between Ceiling Diffusers And Fabric Ductwork Diffusers For Green Buildings, Anthony Fontanini, Michael Olsen, Baskar Ganapathysubramanian Nov 2011

Thermal Comparison Between Ceiling Diffusers And Fabric Ductwork Diffusers For Green Buildings, Anthony Fontanini, Michael Olsen, Baskar Ganapathysubramanian

Mechanical Engineering Publications

Continuously increasing energy standards have driven the need for increasing the efficiency of buildings. Most enhancements to building efficiency have been a result of changes to the heating/cooling systems, improvements in construction materials, or building design code improvements. These approaches neglect the way in which air is dispersed into individual rooms or in a building – i.e., the ducting system. This opens up the possibility of significant energy savings by making ductwork systems lighter and better insulating while ensuring cost effectiveness.

The current study explores this idea by comparing the performance of conventional ductwork with recent advancements in fabric-based ...


Effects Of Mixing Using Side Port Air Injection On A Biomass Fluidized Bed, M. Deza, Theodore J. Heindel, F. Battaglia Oct 2011

Effects Of Mixing Using Side Port Air Injection On A Biomass Fluidized Bed, M. Deza, Theodore J. Heindel, F. Battaglia

Mechanical Engineering Publications

Fluidized beds are being used in practice to gasify biomass to create producer gas, a flammable gas that can be used for process heating. However, recent literature has identified the need to better understand and characterize biomass fluidization hydrodynamics, and has motivated the combined experimental-numerical effort in this work. A cylindrical reactor is considered and a side port is introduced to inject air and promote mixing within the bed. Comparisons between the computational fluid dynamics (CFD) simulations with experiments indicate that three-dimensional simulations are necessary to capture the fluidization behavior of the more complex geometry. This paper considers the effects ...


Coherent Solid/Liquid Interface With Stress Relaxation In A Phase-Field Approach To The Melting/Solidification Transition, Valery I. Levitas, Kamran Samani Oct 2011

Coherent Solid/Liquid Interface With Stress Relaxation In A Phase-Field Approach To The Melting/Solidification Transition, Valery I. Levitas, Kamran Samani

Aerospace Engineering Publications

An advanced Ginzburg-Landau (GL) approach to melting and solidification coupled with mechanics is developed. It is based on the concept of a coherent solid-liquid interface with a transformation strain tensor, the deviatoric part of which is described by a thermodynamically consistent kinetic equation. Due to the relaxation of the elastic energy, a promoting contribution to the driving force for phase transformation in the GL equation appears, both for melting and solidification. Good agreement with known experiments is obtained for Al nanoparticles for the size-dependent melting temperature and temperature-dependent thickness of the surface molten layer. All types of interface stress distributions ...


Surface-Induced Phase Transformations: Multiple Scale And Mechanics Effects And Morphological Transitions, Valery I. Levitas, Mahdi Javanbakht Oct 2011

Surface-Induced Phase Transformations: Multiple Scale And Mechanics Effects And Morphological Transitions, Valery I. Levitas, Mahdi Javanbakht

Aerospace Engineering Publications

Strong, surprising, and multifaceted effects of the width of the external surface layer Δξ and internal stresses on surface-induced pretransformation and phase transformations (PTs) are revealed. Using our further developed phase-field approach, we found that above some critical Δξ*, a morphological transition from fully transformed layer to lack of surface pretransformation occurs for any transformation strain εt. It corresponds to a sharp transition to the universal (independent of εt), strongly increasing the master relationship of the critical thermodynamic driving force for PT Xc on Δξ. For large εt, with increasing Δξ, X ...


3d Simulation Of Wind Turbine Rotors At Full Scale. Part Ii: Fluid–Structure Interaction Modeling With Composite Blades, Y. Bazilevs, Ming-Chen Hsu, J. Kiendel, R. Wuchner, K. U. Bletzigner Oct 2011

3d Simulation Of Wind Turbine Rotors At Full Scale. Part Ii: Fluid–Structure Interaction Modeling With Composite Blades, Y. Bazilevs, Ming-Chen Hsu, J. Kiendel, R. Wuchner, K. U. Bletzigner

Ming-Chen Hsu

In this two-part paper, we present a collection of numerical methods combined into a single framework, which has the potential for a successful application to wind turbine rotor modeling and simulation. In Part 1 of this paper we focus on: 1. The basics of geometry modeling and analysis-suitable geometry construction for wind turbine rotors; 2. The fluid mechanics formulation and its suitability and accuracy for rotating turbulent flows; 3. The coupling of air flow and a rotating rigid body. In Part 2, we focus on the structural discretization for wind turbine blades and the details of the fluid–structure interaction ...


High-Performance Computing Of Wind Turbine Aerodynamics Using Isogeometric Analysis, Ming-Chen Hsu, Ido Akkerman, Yuri Bazilevs Oct 2011

High-Performance Computing Of Wind Turbine Aerodynamics Using Isogeometric Analysis, Ming-Chen Hsu, Ido Akkerman, Yuri Bazilevs

Ming-Chen Hsu

In this article we present a high-performance computing framework for advanced flow simulation and its application to wind energy based on the residual-based variational multiscale (RBVMS) method and isogeometric analysis. The RBVMS formulation and its suitability and accuracy for turbulent flow in a moving domain are presented. Particular emphasis is placed on the parallel implementation of the methodology and its scalability. Two challenging flow cases were considered: the turbulent Taylor–Couette flow and the NREL 5 MW offshore baseline wind turbine rotor at full scale. In both cases, flow quantities of interest from the simulation results compare favorably with the ...


Dimensions Fall 2011, Iowa State University Department Of Mechanical Engineering Oct 2011

Dimensions Fall 2011, Iowa State University Department Of Mechanical Engineering

Dimensions

No abstract provided.


Ultrasonic Attenuation And Backscatter Coefficient Estimates Of Rodent-Tumor-Mimicking Structures: Comparison Of Results Among Clinical Scanners, Kibo Nam, Ivan A. Rosado-Mendez, Lauren A. Wirtzfeld, Alexander D. Pawlicki, Viksit Kumar, Ernest L. Madsen, Goutam Ghoshai, Roberto J. Lavarello, Michael L. Oelze, Timothy A. Bigelow, James A. Zagzebski, William D. O'Brien Jr., Timothy J. Hall Oct 2011

Ultrasonic Attenuation And Backscatter Coefficient Estimates Of Rodent-Tumor-Mimicking Structures: Comparison Of Results Among Clinical Scanners, Kibo Nam, Ivan A. Rosado-Mendez, Lauren A. Wirtzfeld, Alexander D. Pawlicki, Viksit Kumar, Ernest L. Madsen, Goutam Ghoshai, Roberto J. Lavarello, Michael L. Oelze, Timothy A. Bigelow, James A. Zagzebski, William D. O'Brien Jr., Timothy J. Hall

Mechanical Engineering Publications

In vivo estimations of the frequency-dependent acoustic attenuation (α) and backscatter (η) coefficients using radiofrequency (rf) echoes acquired with clinical ultrasound systems must be independent of the data acquisition setup and the estimation procedures. In a recent in vivo assessment of these parameters in rodent mammary tumors, overall agreement was observed among α and η estimates using data from four clinical imaging systems. In some cases, particularly in highly-attenuating heterogeneous tumors, multisystem variability was observed. This paper compares α and η estimates of a well-characterized rodent-tumor-mimicking homogeneous phantom scanned using seven transducers with the same four clinical imaging systems: a ...


High-Speed Ch Planar Laser-Induced Fluorescence Imaging Using A Multimode-Pumped Optical Parametric Oscillator, Joseph D. Miller, Sascha R. Engel, Terrence R. Meyer, Thomas Seeger, Alfred Leipertz Oct 2011

High-Speed Ch Planar Laser-Induced Fluorescence Imaging Using A Multimode-Pumped Optical Parametric Oscillator, Joseph D. Miller, Sascha R. Engel, Terrence R. Meyer, Thomas Seeger, Alfred Leipertz

Mechanical Engineering Publications

We report on high-speed CH planar laser-induced fluorescence (PLIF) imaging in turbulent diffusion flames using a multimode-pumped optical parametric oscillator (OPO). The OPO is pumped by the third-harmonic output of a multimode Nd:YAG cluster for direct signal excitation in the A-X (0,0) band of the CH radical. The lasing threshold, conversion efficiency, and linewidth are shown to depend on the number of pump passes in the ring cavity of the OPO. Single-shot CH PLIF images are acquired at 10 kHz with excitation energy up to 6 mJ=pulse at 431:1nm. Signalto- noise ratios of ∼25–35 are ...


Apparatus For Focused Electric-Field Imprinting For Micron And Sub-Micron Patterns On Wavy Or Planar Surfaces, Abhijit Chandra, Ashraf F. Bastawros, Ambar K. Mitra, Charles A. Lemaire Aug 2011

Apparatus For Focused Electric-Field Imprinting For Micron And Sub-Micron Patterns On Wavy Or Planar Surfaces, Abhijit Chandra, Ashraf F. Bastawros, Ambar K. Mitra, Charles A. Lemaire

Aerospace Engineering Patents

A Focused Electric Field Imprinting (FEFI) process and apparatus provides a focused electric field to guide an unplating operation and/or a plating operation to form very fine-pitched metal patterns on a substrate. The process is a variation of the electrochemical unplating process, wherein the process is modified for imprinting range of patterns of around 2000 microns to 20 microns or less in width, and from about 0.1 microns or less to 10 microns or more in depth. Some embodiments curve a proton-exchange membrane whose shape is varied using suction on a backing fluid through a support mask. Other ...


Phase-Field Modeling Of Fracture In Liquid, Valery I. Levitas, Alexander V. Idesman, Ameeth K. Palakala Aug 2011

Phase-Field Modeling Of Fracture In Liquid, Valery I. Levitas, Alexander V. Idesman, Ameeth K. Palakala

Aerospace Engineering Publications

Phase-field theory for the description of the overdriven fracture in liquid (cavitation) in tensile pressure wave is developed. Various results from solid mechanics are transferred into mechanics of fluids. Thermodynamic potential is formulated that describes the desired tensile pressure–volumetric strain curve and for which the infinitesimal damage produces infinitesimal change in the equilibrium bulk modulus. It is shown that the gradient of the order parameter should not be included in the energy, in contrast to all known phase-field approaches for any material instability. Analytical analysis of the equations is performed. Problems relevant to the melt-dispersion mechanism of the reaction ...


Uniaxial Three-Dimensional Shape Measurement With Projector Defocusing, Ying Xu, Laura Ekstrand, Song Zhang Aug 2011

Uniaxial Three-Dimensional Shape Measurement With Projector Defocusing, Ying Xu, Laura Ekstrand, Song Zhang

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Our recent study showed that the phase error caused by improperly defocused binary structured patterns has a unique relationship with the depth z. Based on this finding, the depth information can be extracted without the need of triangulation. Because the measurement can be performed from the same viewing angle, this uniaxial measurement technique can overcome some limitations of a triangulation-based technique, such as measuring a deep hole. This paper will present the principle of the proposed technique and show some simulation and preliminary experimental results to verify its viability.


U.S. Billion-Ton Update: Biomass Supply For A Bioenergy And Bioproducts Industry, United States Department Of Energy, Robert D. Perlack, Laurence M. Eaton, Anthony F. Turhollow Jr., Matt H. Langholtz, Craig C. Brandt, Mark E. Downing, Robin L. Graham, Lynn L. Wright, Jacob M. Kavkewitz, Anna M. Shamey, Richard G. Nelson, Bryce J. Stokes, William L. Rooney, David J. Muth Jr., J. Richard Hess, Jared M. Abodeely, Chad Hellwinckel, Danial De La Torre Ugarte, Daniel C. Yoder, James P. Lyon, Timothy G. Rials, Timothy A. Volk, Thomas S. Buchholz, Lawrence P. Abrahamson, Robert P. Anex, Thomas B. Voigt, William Berguson, Don E. Riemenschneider, Douglas Karlen, Jane M. F. Johnson, Robert B. Mitchell, Kenneth P. Vogel, Edward P. Richard Jr., John Tatarko, Larry E. Wagner, Kenneth E. Skog, Patricia K. Lebow, Dennis P. Dykstra, Marilyn A. Buford, Patrick D. Miles, D. Andrew Scott, James H. Perdue, Robert B. Rummer, Jamie Barbour, John A. Stanturf, David B. Mckeever, Ronald S. Zalesny Jr., Edmund A. Gee, P. Daniel Cassidy, David Lightle Aug 2011

U.S. Billion-Ton Update: Biomass Supply For A Bioenergy And Bioproducts Industry, United States Department Of Energy, Robert D. Perlack, Laurence M. Eaton, Anthony F. Turhollow Jr., Matt H. Langholtz, Craig C. Brandt, Mark E. Downing, Robin L. Graham, Lynn L. Wright, Jacob M. Kavkewitz, Anna M. Shamey, Richard G. Nelson, Bryce J. Stokes, William L. Rooney, David J. Muth Jr., J. Richard Hess, Jared M. Abodeely, Chad Hellwinckel, Danial De La Torre Ugarte, Daniel C. Yoder, James P. Lyon, Timothy G. Rials, Timothy A. Volk, Thomas S. Buchholz, Lawrence P. Abrahamson, Robert P. Anex, Thomas B. Voigt, William Berguson, Don E. Riemenschneider, Douglas Karlen, Jane M. F. Johnson, Robert B. Mitchell, Kenneth P. Vogel, Edward P. Richard Jr., John Tatarko, Larry E. Wagner, Kenneth E. Skog, Patricia K. Lebow, Dennis P. Dykstra, Marilyn A. Buford, Patrick D. Miles, D. Andrew Scott, James H. Perdue, Robert B. Rummer, Jamie Barbour, John A. Stanturf, David B. Mckeever, Ronald S. Zalesny Jr., Edmund A. Gee, P. Daniel Cassidy, David Lightle

Agricultural and Biosystems Engineering Technical Reports and White Papers

The Report, Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply (generally referred to as the Billion-Ton Study or 2005 BTS), was an estimate of “potential” biomass within the contiguous United States based on numerous assumptions about current and future inventory and production capacity, availability, and technology. In the 2005 BTS, a strategic analysis was undertaken to determine if U.S. agriculture and forest resources have the capability to potentially produce at least one billion dry tons of biomass annually, in a sustainable manner—enough to displace approximately 30% of the country ...


“Auto-Exposure For 3d Shape Measurement With A Digital Fringe Projection Technique, Laura Ekstrand, Song Zhang Aug 2011

“Auto-Exposure For 3d Shape Measurement With A Digital Fringe Projection Technique, Laura Ekstrand, Song Zhang

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Automatically adapting the camera exposure time is crucial for industrial applications where minimum human intervention is usually desirable. However, it is very challenging to realize such a capability for a conventional fringe projection system where only a finite increment of the exposure time is allowed due to its digital fringe generation nature. Our recent study on generating sinusoidal fringe patterns by properly defocusing binary ones permits the use of an arbitrary exposure time. This provides the potential to adapt the exposure time automatically. This paper will present the principle of an automatic exposure technique and show some experimental results.


Single-Shot Gas-Phase Thermometry Using Purerotational Hybrid Femtosecond/Picosecond Coherent Anti-Stokes Raman Scattering, Joseph D. Miller, Sukesh Roy, Mikhail N. Slipchenko, James R. Gord, Terrence R. Meyer Aug 2011

Single-Shot Gas-Phase Thermometry Using Purerotational Hybrid Femtosecond/Picosecond Coherent Anti-Stokes Raman Scattering, Joseph D. Miller, Sukesh Roy, Mikhail N. Slipchenko, James R. Gord, Terrence R. Meyer

Mechanical Engineering Publications

High-repetition-rate, single-laser-shot measurements are important for the investigation of unsteady flows where temperature and species concentrations can vary significantly. Here, we demonstrate singleshot, pure-rotational, hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) thermometry based on a kHz-rate fs laser source. Interferences that can affect nanosecond (ns) and ps CARS, such as nonresonant background and collisional dephasing, are eliminated by selecting an appropriate time delay between the 100-fs pump/Stokes pulses and the pulse-shaped 8.4-ps probe. A time- and frequency-domain theoretical model is introduced to account for rotational-level dependent collisional dephasing and indicates that the optimal probe-pulse time ...


Phase Transition And Structure Of Silver Azide At High Pressure, Dongbin Hou, Fuxiang Zhang, Cheng Ji, Trevor Hannon, Hongyang Zhu, Jianzhe Wu, Valery I. Levitas, Yanzhang Ma Jul 2011

Phase Transition And Structure Of Silver Azide At High Pressure, Dongbin Hou, Fuxiang Zhang, Cheng Ji, Trevor Hannon, Hongyang Zhu, Jianzhe Wu, Valery I. Levitas, Yanzhang Ma

Aerospace Engineering Publications

ilver azide (AgN 3) was compressed up to 51.3 GPa. The results reveal a reversible second-order orthorhombic-to-tetragonal phase transformation starting from ambient pressure and completing at 2.7 GPa. The phase transition is accompanied by a proximity of cell parameters aand b, a 3° rotation of azide anions, and a change of coordination number from 4-4 (four short, four long) to eight fold. The crystal structure of the high pressure phase is determined to be inI4/mcm space group, with Ag at 4a, N1 at 4d, and N2 at 8h Wyckoff positions. Both of ...


Thermal Conductivity Reduction Through Isotope Substitution In Nanomaterials: Predictions From An Analytical Classical Model And Nonequilibrium Molecular Dynamics Simulations, Ganesh Balasubramanian, Ishwar K. Puri, Michael C. Bohm, Frederic Leroy Jul 2011

Thermal Conductivity Reduction Through Isotope Substitution In Nanomaterials: Predictions From An Analytical Classical Model And Nonequilibrium Molecular Dynamics Simulations, Ganesh Balasubramanian, Ishwar K. Puri, Michael C. Bohm, Frederic Leroy

Ganesh Balasubramanian

We introduce an analytical model to rapidly determine the thermal conductivity reduction due to mass disorder in nanomaterials. Although this simplified classical model depends only on the masses of the different atoms, it adequately describes the changes in thermal transport as the concentrations of these atoms vary. Its predictions compare satisfactorily with nonequilibrium molecular dynamics simulations of the thermal conductivity of 14C–12C carbon nanotubes as well as with previous simulations of other materials. We present it as a simple tool to quantitatively estimate the thermal conductivity decrease that is induced by isotope substitution in various materials.


A Review Of X-Ray Flow Visualization With Applications To Multiphase Flows, Theodore J. Heindel Jul 2011

A Review Of X-Ray Flow Visualization With Applications To Multiphase Flows, Theodore J. Heindel

Mechanical Engineering Publications

Flow visualization and characterization of multiphase flows have been the quest of many fluid mechanicians. The process is fairly straight forward only when there is good optical access (i.e., the vessel is not opaque or there are appropriate viewing ports) and the flow is transparent, implying a very low volume fraction of the dispersed phase; however, when optical access is not good or the fluid is opaque, alternative methods must be developed. Several different noninvasive visualization tools have been developed to provide high-quality qualitative and quantitative data of various multiphase flow characteristics, and overviews of these methods have appeared ...


Abstracts, Review Of Progress In Quantitative Nondestructive Evaluation (Burlington, Vermont, July 17-22, 2011), Center For Nondestructive Evaluation, Iowa State University Jul 2011

Abstracts, Review Of Progress In Quantitative Nondestructive Evaluation (Burlington, Vermont, July 17-22, 2011), Center For Nondestructive Evaluation, Iowa State University

Review of Progress in Quantitative Nondestructive Evaluation

Abstracts of papers presented at the 2011 Review of Progress in Quantitative Nondestructive Evaluation (QNDE) conference held in Burlington, Vermont from July 17–22, 2011.


Heat Conduction Across A Solid-Solid Interface: Understanding Nanoscale Interfacial Effects On Thermal Resistance, Ganesh Balasubramanian, Ishwar K. Puri Jul 2011

Heat Conduction Across A Solid-Solid Interface: Understanding Nanoscale Interfacial Effects On Thermal Resistance, Ganesh Balasubramanian, Ishwar K. Puri

Ganesh Balasubramanian

Phonons scatter and travel ballistically in systems smaller than the phonon mean free path. At larger lengths, the transport is instead predominantly diffusive. We employ molecular dynamics simulations to describe the length dependence of the thermal conductivity. The simulations show that the interfacial thermal resistance Rk for a Si-Ge superlattice is inversely proportional to its length, but reaches a constant value as the system dimension becomes larger than the phonon mean free path. This nanoscale effect is incorporated into an accurate continuum model by treating the interface as a distinct material with an effective thermal resistance equal to Rk .


Developing Tracer Particles For X-Ray Particle Tracking Velocimetry, Joshua B. Drake, Andrea L. Kenney, Timothy B. Morgan, Theodore J. Heindel Jul 2011

Developing Tracer Particles For X-Ray Particle Tracking Velocimetry, Joshua B. Drake, Andrea L. Kenney, Timothy B. Morgan, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

X-ray imaging, as a noninvasive flow visualization technique, has been shown to be a useful method for observing and characterizing multiphase flows. One type of X-ray flow visualization technique, called X-ray Particle Tracking Velocimetry (XPTV), tracks an X-ray attenuating particle in an opaque fluid flow. A significant challenge with XPTV is identifying tracer particles with the desired fluid flow characteristics (e.g., small and neutrally buoyant) but yet differentially attenuate X-rays, which is based primarily on density differences. This paper describes the manufacturing of XPTV tracer particles that satisfy specific particle characteristics including high X-ray attenuation, uniform shape, specified effective ...


Cavitation From A Butterfly Valve: Comparing 3d Simulations To 3d X-Ray Computed Tomography Flow Visualization, Graham Brett, Marc Riveland, Terrence C. Jensen, Theodore J. Heindel Jul 2011

Cavitation From A Butterfly Valve: Comparing 3d Simulations To 3d X-Ray Computed Tomography Flow Visualization, Graham Brett, Marc Riveland, Terrence C. Jensen, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Flow control valves may experience localized cavitation when the local static pressure drops to the liquid vapor pressure. Localized damage to the valve and surrounding area can occur when the vapor cavity collapses. Valve designs that reduce cavitation are based on empirical evidence and accumulated experience, but there are still considerable cavitation problems in industry. Valve designers may use computational fluid dynamics (CFD) to simulate cavitation in flow control valves, but model validation is challenging because there are limited data of local cavitation from the valve surface. Typically, the intensity of cavitation in a control valve is inferred from measurements ...


Virtual Reality Integrated Welder Training, Richard T. Stone, Kristopher Patrick Watts, Peihan Zhong Jul 2011

Virtual Reality Integrated Welder Training, Richard T. Stone, Kristopher Patrick Watts, Peihan Zhong

Industrial and Manufacturing Systems Engineering Publications

Training in the welding industry is a critical and often costly endeavor; this study examines the training potential, team learning, material consumption, and cost implications of using integrated virtual reality technology as a major part of welder training. In this study, 22 participants were trained using one of two separate methods (traditional training (TT) and virtual reality integrated training (VRI)). The results demonstrated that students trained using 50% virtual reality had training outcomes that surpassed those of traditionally trained students across four distinctive weld qualifications (2F, 1G, 3F, 3G). In addition, the VRI group demonstrated significantly higher levels of team ...


Probe-Pulse Optimization For Nonresonant Suppression In Hybrid Fs/Ps Coherent Anti-Stokes Raman Scattering At High Temperature, Joseph D. Miller, Mikhail N. Slipchenko, Terrence R. Meyer Jul 2011

Probe-Pulse Optimization For Nonresonant Suppression In Hybrid Fs/Ps Coherent Anti-Stokes Raman Scattering At High Temperature, Joseph D. Miller, Mikhail N. Slipchenko, Terrence R. Meyer

Mechanical Engineering Publications

Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) offers accurate thermometry at kHz rates for combustion diagnostics. In high-temperature flames, selection of probe-pulse characteristics is key to simultaneously optimizing signal-to-nonresonant-background ratio, signal strength, and spectral resolution. We demonstrate a simple method for enhancing signal-to-nonresonant-background ratio by using a narrowband Lorentzian filter to generate a time-asymmetric probe pulse with full-width-half-maximum (FWHM) pulse width of only 240 fs. This allows detection within just 310 fs after the Raman excitation for eliminating nonresonant background while retaining 45% of the resonant signal at 2000 K. The narrow linewidth is comparable to that ...


Computationally Efficient Solution To The Cahn–Hilliard Equation: Adaptive Implicit Time Schemes, Mesh Sensitivity Analysis And The 3d Isoperimetric Problem, Olga Wodo, Baskar Ganapathysubramanian Jul 2011

Computationally Efficient Solution To The Cahn–Hilliard Equation: Adaptive Implicit Time Schemes, Mesh Sensitivity Analysis And The 3d Isoperimetric Problem, Olga Wodo, Baskar Ganapathysubramanian

Mechanical Engineering Publications

We present an efficient numerical framework for analyzing spinodal decomposition described by the Cahn–Hilliard equation. We focus on the analysis of various implicit time schemes for two and three dimensional problems. We demonstrate that significant computational gains can be obtained by applying embedded, higher order Runge–Kutta methods in a time adaptive setting. This allows accessing time-scales that vary by five orders of magnitude. In addition, we also formulate a set of test problems that isolate each of the sub-processes involved in spinodal decomposition: interface creation and bulky phase coarsening. We analyze the error fluctuations using these test problems ...


Model-Assisted Development Of A Laminography Inspection System, Robert J. Grandin, Joseph N. Gray Jul 2011

Model-Assisted Development Of A Laminography Inspection System, Robert J. Grandin, Joseph N. Gray

Center for Nondestructive Evaluation Conference Papers, Posters and Presentations

Traditional computed tomography (CT) is an effective method of determining the internal structure of an object through non-destructive means; however, inspection of certain objects, such as those with planar geometrics or with limited access, requires an alternate approach. An alternative is laminography and has been the focus of a number of researchers in the past decade for both medical and industrial inspections. Many research efforts rely on geometrically-simple analytical models, such as the Shepp-Logan phantom, for the development of their algorithms. Recent work at the Center for Non-Destructive Evaluation makes extensive use of a forward model, XRSIM, to study artifacts ...