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Full-Text Articles in Mechanical Engineering

Thermoelectric Module-Variable Conductance Heat Pipe Assemblies For Reduced Power Temperature Control, Corey Melnick, Marc Hodes, Gennady Ziskind, Martin Cleary, Vincent Manno Aug 2012

Thermoelectric Module-Variable Conductance Heat Pipe Assemblies For Reduced Power Temperature Control, Corey Melnick, Marc Hodes, Gennady Ziskind, Martin Cleary, Vincent Manno

Vincent P. Manno

Thermoelectric modules (TEMs) are used to precisely maintain the setpoint temperature of photonic components generating variable heat loads under varying ambient conditions. The non-component side of TEMs is mounted onto conventional heat sinks (CHSs). At any combination of setpoint temperature, heat load and ambient temperature, there is a unique thermal resistance between the non-component side of a TEM and the ambient corresponding to minimal TEM power consumption. Indeed, a zero thermal resistance heat sink minimizes power consumption when a TEM operates in refrigeration mode, but when it operates in heating mode a relatively high thermal resistance one is optimal. This ...


Simulated Effects Of Measurement Noise On Contact Measurements Between Rough And Smooth Surfaces, Caprice Gray, Robert White, Vincent Manno, Chris Rogers Aug 2012

Simulated Effects Of Measurement Noise On Contact Measurements Between Rough And Smooth Surfaces, Caprice Gray, Robert White, Vincent Manno, Chris Rogers

Vincent P. Manno

To test the accuracy of optically measuring contact, we examined the height distribution histogram of a simulated rough surface contacting a smooth surface. We qualified the technique sensitivity as a function of the inverse signal-to-noise ratio having values ranging from 0 to 0.3. An explanation of how the analysis technique can be applied to Dual Emission Laser-Induced Fluorescence (DELIF) measurements is provided.


Modeling Of Dual Emission Laser Induced Fluorescence For Slurry Thickness Measurements In Chemical Mechanical Polishing, Caprice Gray, Chris Rogers, Vincent Manno, Robert White Aug 2012

Modeling Of Dual Emission Laser Induced Fluorescence For Slurry Thickness Measurements In Chemical Mechanical Polishing, Caprice Gray, Chris Rogers, Vincent Manno, Robert White

Vincent P. Manno

Dual emission laser induced fluorescence (DELIF) is a technique for measuring the instantaneous thin fluid film thickness in dynamic systems. Two fluorophores within the system produce laser induced emissions that are filtered and captured by two cameras. The ratio of the images from these cameras is used to cancel the effect of the laser beam profile on the image intensity. The resultant intensity ratio can be calibrated to a fluid film thickness. The utilization of a 2-dye system when applied to Chemical Mechanical Polishing (CMP) is complicated by the fluorescence of the polymeric polishing pad and the light scattering particles ...


Visor Scratch Repair And Prevention, Andrew Heafitz, Benjamin Linder, Marta Luczynska, Mark Scott Aug 2012

Visor Scratch Repair And Prevention, Andrew Heafitz, Benjamin Linder, Marta Luczynska, Mark Scott

Benjamin Linder

Severe eye injuries occur in 30 percent of demining accidents. Visors are known to be effective personal protective equipment when worn properly, but deminers often lift or remove their visors because scratches, glare or fog make them hard to see through, or because they are hot, heavy and uncomfortable to wear. Addressing each of these specific design problems could increase visor use and prevent a significant number of debilitating injuries. This paper presents methods for preventing and eliminating scratches on demining visors.


Improving Endmilling Surface Finish By Workpiece Rotation And Adaptive Toolpath Spacing, Athulan Vijayaraghavan, Aaron Hoover, Jeffrey Hartnett, David Dornfeld Jul 2012

Improving Endmilling Surface Finish By Workpiece Rotation And Adaptive Toolpath Spacing, Athulan Vijayaraghavan, Aaron Hoover, Jeffrey Hartnett, David Dornfeld

Aaron M. Hoover

Free-form surfaces are being used in a growing number of engineering applications, especially in injection molding of consumer products. Decreasing the manufacturing cost and time of these molds will improve the efficiency of manufacturing injection molded consumer products. This paper is motivated by the need for simple strategies to improve the quality of and decrease the time required to machine free-form surfaces. We present two methods to improve the surface finish of parts finished with ball-nose endmilling. In the first method the surface finish is improved by finding an optimal orientation angle for the workpiece relative to the machining axis ...


Trajectory Generation In High-Speed, High-Precision Micromilling Using Subdivision Surfaces, Athulan Vijayaraghavan, Angela Sodemann, Aaron Hoover, J. Mayor, David Dornfeld Jul 2012

Trajectory Generation In High-Speed, High-Precision Micromilling Using Subdivision Surfaces, Athulan Vijayaraghavan, Angela Sodemann, Aaron Hoover, J. Mayor, David Dornfeld

Aaron M. Hoover

Motion control in high-speed micromilling processes requires fast, accurate following of a specified curvilinear path. The accuracy with which the path can be followed is determined by the speed at which individual trajectories can be generated and sent to the control system. The time required to generate the trajectory is dependent on the representations used for the curvilinear trajectory path. In this study, we introduce the use of subdivision curves as a method for generating high-speed micromilling trajectories. Subdivision curves are discretized curves which are specified as a series of recursive refinements of a coarse mesh. By applying these recursive ...


The Effect Of Streamwise Vortices On The Frost Growth Rate In Developing Laminar Channel Flows, Brian Storey, Anthony Jacobi Jul 2012

The Effect Of Streamwise Vortices On The Frost Growth Rate In Developing Laminar Channel Flows, Brian Storey, Anthony Jacobi

Brian Storey

An experimental study is presented to assess the influence of streamwise vortices on frost growth in a steady, developing, laminar channel flow. Using a simple model and scale analysis, frost growth rate (ablimation) data are normalized with respect to temperature, humidity and time. Measurements from baseline experiments in a rectangular channel are found to be accurately correlated using the proposed scaling relation. Upon introducing streamwise vortices in the channel flow, frost growth still follows the scaling relation, but local growth rates were observed to increase by more than 7% in regions where the streamwise vortices induce a surface-normal flow toward ...


Precis: A Usercentric Word-Length Optimization Tool, Mark Chang, Scott Hauck Jul 2012

Precis: A Usercentric Word-Length Optimization Tool, Mark Chang, Scott Hauck

Mark L. Chang

Translating an algorithm designed for a general-purpose processor into an algorithm optimized for custom logic requires extensive knowledge of the algorithm and the target hardware. Precis lets designers analyze the precision requirements of algorithms specified in Matlab. The design time tool combines simulation, user input, and program analysis to help designers focus their manual precision optimization efforts.


Markov Chain Monte Carlo-Based Method For Flaw Detection In Beams, Christopher Lee, Ronald Glaser, John Nitao, Tracy Hickling, William Hanley Apr 2012

Markov Chain Monte Carlo-Based Method For Flaw Detection In Beams, Christopher Lee, Ronald Glaser, John Nitao, Tracy Hickling, William Hanley

Christopher Lee

A Bayesian inference methodology using a Markov chain Monte Carlo (MCMC) sampling procedure is presented for estimating the parameters of computational structural models. This methodology combines prior information, measured data, and forward models to produce a posterior distribution for the system parameters of structural models that is most consistent with all available data. The MCMC procedure is based upon a Metropolis-Hastings algorithm that is shown to function effectively with noisy data, incomplete data sets, and mismatched computational nodes/measurement points. A series of numerical test cases based upon a cantilever beam is presented. The results demonstrate that the algorithm is ...


Nonlinear Dynamics And Loop Formation In Kirchoff Rods With Implications To The Mechanics Of Dna And Cables, Sachin Goyal, Noel Perkins, Christopher Lee Apr 2012

Nonlinear Dynamics And Loop Formation In Kirchoff Rods With Implications To The Mechanics Of Dna And Cables, Sachin Goyal, Noel Perkins, Christopher Lee

Christopher Lee

The paper contributes a general dynamical formulation and numerical solution procedure for studying nonlinear and three-dimensional dynamics of Kirchhoffrods. Target applications include the dynamic formation of DNA loops and supercoils as well as loops (hockles) in marine cables. The formulation accommodates non-homogeneous and non-isotropic inextensible rods both with and without coupling of tension and torsion. The utility of this formulation is illustrated by studying the dynamics and quasi-static response of a clamped–clamped rod subject to compression and/or twist. For slow loading rates, the computed quasi-static responses converge to published equilibrium solutions for a benchmark problem. As loading rates ...


The Stiffness Of Three-Dimensional Ionic Self-Assembling Peptide Gels Affects The Extent Of Capillary-Like Network Formation, Alisha Sarang-Sieminski, A Was, G Kim, Haiyan Gong, Roger Kamm Apr 2012

The Stiffness Of Three-Dimensional Ionic Self-Assembling Peptide Gels Affects The Extent Of Capillary-Like Network Formation, Alisha Sarang-Sieminski, A Was, G Kim, Haiyan Gong, Roger Kamm

Alisha L. Sarang-Sieminski

Improving our ability to control capillary morphogenesis has implications for not only better understanding of basic biology, but also for applications in tissue engineering and in vitro testing. Numerous biomaterials have been investigated as cellular supports for these applications and the biophysical environment biomaterials provide to cells has been increasingly recognized as an important factor in directing cell function. Here, the ability of ionic self-assembling peptide gels to support capillary morphogenesis and the effect of their mechanical properties is investigated. When placed in a physiological salt solution, these oligopeptides spontaneously self-assemble into gels with an extracellular matrix (ECM)-like microarchitecture ...


Electrohydrodynamic Instabilities In Microchannels With Time Periodic Forcing, David Boy, Brian D. Storey Mar 2012

Electrohydrodynamic Instabilities In Microchannels With Time Periodic Forcing, David Boy, Brian D. Storey

Brian Storey

In microfluidic applications it has been observed that flows with spatial gradients in electrical conductivity are unstable under the application of sufficiently strong electric fields. These electrohydrodynamic instabilities can drive a nonlinear flow despite the low Reynolds number. Such flows hold promise as a simple mechanism for mixing fluids. In this work, the effect of a time periodic electric field on the instability is explored. The case where an electric field is applied across a diffuse interface of two fluids with varying electrical conductivity is considered. Frequency-dependent behavior is found only in the regime where the instability growth rates are ...


Electrokinetic Instabilities In Thin Microchannels, Brian D. Storey, Burt S. Tilley, Hao Lin, Juan G. Santiago Mar 2012

Electrokinetic Instabilities In Thin Microchannels, Brian D. Storey, Burt S. Tilley, Hao Lin, Juan G. Santiago

Brian Storey

An important class of electrokinetic, microfluidic devices aims to pump and control electrolyte working liquids that have spatial gradients in conductivity. These high-gradient flows can become unstable under the application of a sufficiently strong electric field. In many of these designs, flow channels are thin in the direction orthogonal to the main flow and the conductivity gradient. Viscous stresses due to the presence of these walls introduce a stabilizing force that plays a major role in determining the overall instability. A thin channel model for fluid flow is developed and shown to provide good agreement with a complete three-dimensional model ...


Bistability In A Simple Fluid Network Due To Viscosity Contrast, John Geddes, Brian Storey, David Gardner, Russell Carr Mar 2012

Bistability In A Simple Fluid Network Due To Viscosity Contrast, John Geddes, Brian Storey, David Gardner, Russell Carr

Brian Storey

We study the existence of multiple equilibrium states in a simple fluid network using Newtonian fluids and laminar flow. We demonstrate theoretically the presence of hysteresis and bistability, and we confirm these predictions in an experiment using two miscible fluids of different viscosity—sucrose solution and water. Possible applications include blood flow, microfluidics, and other network flows governed by similar principles.


A Depth-Averaged Electrokinetic Flow Model For Shallow Microchannels, Hao Lin, Brian D. Storey, Juan G. Santiago Mar 2012

A Depth-Averaged Electrokinetic Flow Model For Shallow Microchannels, Hao Lin, Brian D. Storey, Juan G. Santiago

Brian Storey

Electrokinetic flows with heterogeneous conductivity configuration occur widely in microfluidic applications such as sample stacking and multidimensional assays. Electromechanical coupling in these flows may lead to complex flow phenomena, such as sample dispersion due to electro-osmotic velocity mismatch, and electrokinetic instability (EKI). In this work we develop a generalized electrokinetic model suitable for the study of microchannel flows with conductivity gradients and shallow-channel geometry. An asymptotic analysis is performed with the channel depth-to-width ratio as a smallness parameter, and the three-dimensional equations are reduced to a set of depth-averaged equations governing in-plane flow dynamics. The momentum equation uses a Darcy ...


Instability Of Electro-Osmotic Channel Flow With Streamwise Conductivity Gradients, Jose Santos, Brian D. Storey Mar 2012

Instability Of Electro-Osmotic Channel Flow With Streamwise Conductivity Gradients, Jose Santos, Brian D. Storey

Brian Storey

This work considers the stability of an electro-osmotic microchannel flow with streamwise electrical conductivity gradients, a configuration common in microfluidic applications such as field amplified sample stacking. Previous work on such flows has focused on how streamwise conductivity gradients set a nonuniform electro-osmotic velocity which results in dispersion of the conductivity field. However, it has been known for many years that electric fields can couple with conductivity gradients to generate unstable flows. This work demonstrates that at high electric fields such an electrohydrodynamic instability arises in this configuration and the basic mechanisms are explored through numerical simulations. The instability is ...


Argon Rectification And The Cause Of Light Emission In Single-Bubble Sonoluminescence, Brian D. Storey, Andrew J. Szeri Mar 2012

Argon Rectification And The Cause Of Light Emission In Single-Bubble Sonoluminescence, Brian D. Storey, Andrew J. Szeri

Brian Storey

In single-bubble sonoluminescence, repeated brief flashes of light are produced in a gas bubble strongly driven by a periodic acoustic field. A startling hypothesis has been made by Lohse and co-workers [Phys. Rev. Lett. 78, 1359 (1997)] that the non-noble gases in an air bubble undergo chemical reaction into soluble products, leaving only argon. In the present work, this dissociation hypothesis is supported by simulations, although the associated temperatures of about 7000 K seem too low for bremsstrahlung, which has been proposed as the dominant light emission mechanism. This suggests that emission from water vapor and its reaction products, heretofore ...


Steric Effects On Ac Electro-Osmosis In Dilute Electrolytes, Brian D. Storey, Lee Edwards, Mustafa Sabri Kilic, Martin Z. Bazant Mar 2012

Steric Effects On Ac Electro-Osmosis In Dilute Electrolytes, Brian D. Storey, Lee Edwards, Mustafa Sabri Kilic, Martin Z. Bazant

Brian Storey

The current theory of alternating-current electro-osmosis (ACEO) is unable to explain the experimentally observed flow reversal of planar ACEO pumps at high frequency (above the peak, typically 10–100 kHz), low salt concentration (1–1000 μM), and moderate voltage (2–6 V), even taking into account Faradaic surface reactions, nonlinear double-layer capacitance, and bulk electrothermal flows. We attribute this failure to the breakdown of the classical Poisson-Boltzmann model of the diffuse double layer, which assumes a dilute solution of pointlike ions. In spite of low bulk salt concentration, the large voltage induced across the double layer leads to crowding of ...


Inertially Driven Inhomogeneities In Violently Collapsing Bubbles: The Validity Of The Rayleigh-Plesset Equation, Hao Lin, Brian D. Storey, Andrew J. Szeri Mar 2012

Inertially Driven Inhomogeneities In Violently Collapsing Bubbles: The Validity Of The Rayleigh-Plesset Equation, Hao Lin, Brian D. Storey, Andrew J. Szeri

Brian Storey

When a bubble collapses mildly the interior pressure field is spatially uniform; this is an assumption often made to close the Rayleigh-Plesset equation of bubble dynamics. The present work is a study of the self-consistency of this assumption, particularly in the case of violent collapses. To begin, an approximation is developed for a spatially non-uniform pressure field, which in a violent collapse is inertially driven. Comparisons of this approximation show good agreement with direct numerical solutions of the compressible Navier-Stokes equations with heat and mass transfer. With knowledge of the departures from pressure uniformity in strongly forced bubbles, one is ...


Rayleigh-Taylor Instability Of Violently Collapsing Bubbles, Hao Lin, Brian D. Storey, Andrew J. Szeri Mar 2012

Rayleigh-Taylor Instability Of Violently Collapsing Bubbles, Hao Lin, Brian D. Storey, Andrew J. Szeri

Brian Storey

In a classical paper Plesset has determined conditions under which a bubble changing in volume maintains a spherical shape. The stability analysis was further developed by Prosperetti to include the effects of liquid viscosity on the evolving shape modes. In the present work the theory is further modified to include the changing density of the bubble contents. The latter is found to be important in violent collapses where the densities of the gas and vapor within a bubble may approach densities of the liquid outside. This exerts a stabilizing influence on the Rayleigh–Taylor mechanism of shape instability of spherical ...


Shape Stability Of Sonoluminescence Bubbles: Comparison Of Theory To Experiments, Brian Storey Mar 2012

Shape Stability Of Sonoluminescence Bubbles: Comparison Of Theory To Experiments, Brian Storey

Brian Storey

Single bubble sonoluminescence (SBSL) is the brief flash of light emitted from a single, stable, acoustically forced bubble. In experiments, the maximum pressure amplitude with which a bubble may be forced is limited by considerations of spherical stability. The traditional linear stability analysis predicts a threshold for SBSL at a much lower pressure amplitude than experimental observations. This work shows that if one constructs an accurate model of the radial dynamics, the traditional linear stability analysis predicts a boundary that is in excellent agreement with experimental data.


Bulk Electroconvective Instability At High Péclet Numbers, Brian D. Storey, Boris Zaltzman, Isaak Rubinstein Mar 2012

Bulk Electroconvective Instability At High Péclet Numbers, Brian D. Storey, Boris Zaltzman, Isaak Rubinstein

Brian Storey

Bulk electroconvection pertains to flow induced by the action of a mean electric field upon the residual space charge in the macroscopic regions of a locally quasielectroneutral strong electrolyte. For a long time, controversy has existed in the literature as to whether quiescent electric conduction from such an electrolyte into a uniform charge-selective solid, such as a metal electrode or ion exchange membrane, is stable with respect to bulk electroconvection. While it was recently claimed that bulk electroconvective instability could not occur, this claim pertained to an aqueous, low-molecular-weight electrolyte characterized by an order-unity electroconvection Péclet number. In this paper ...


Field-Amplified Sample Stacking And Focusing In Nanofluidic Channels, Jess M. Sustarich, Brian D. Storey, Sumita Pennathur Mar 2012

Field-Amplified Sample Stacking And Focusing In Nanofluidic Channels, Jess M. Sustarich, Brian D. Storey, Sumita Pennathur

Brian Storey

Nanofluidic technology is gaining popularity for bioanalytical applications due to advances in both nanofabrication and design. One major obstacle in the widespread adoption of such technology for bioanalytical systems is efficient detection of samples due to the inherently low analyte concentrations present in such systems. This problem is exacerbated by the push for electronic detection, which requires an even higher sensor-local sample concentration than optical detection. This paper explores one of the most common preconcentration techniques, field-amplified sample stacking, in nanofluidic systems in efforts to alleviate this obstacle. Holding the ratio of background electrolyte concentrations constant, the parameters of channel ...


Modeling The Collagen Fibril Network Of Biological Tissues As A Nonlinearly Elastic Material Using A Continuous Volume Fraction Distribution Function, Reza Shirazi, Pasquale Vena, Robert L. Sah, Stephen M. Klisch Dec 2011

Modeling The Collagen Fibril Network Of Biological Tissues As A Nonlinearly Elastic Material Using A Continuous Volume Fraction Distribution Function, Reza Shirazi, Pasquale Vena, Robert L. Sah, Stephen M. Klisch

Stephen M. Klisch

Despite distinct mechanical functions, biological soft tissues have a common microstructure in which a ground matrix is reinforced by a collagen fibril network. The microstructural properties of the collagen network contribute to continuum mechanical tissue properties that are strongly anisotropic with tensile-compressive asymmetry. In this study, a novel approach based on a continuous distribution of collagen fibril volume fractions is developed to model fibril reinforced soft tissues as nonlinearly elastic and anisotropic material. Compared with other approaches that use a normalized number of fibrils for the definition of the distribution function, this representation is based on a distribution parameter (i ...


A Benchmark Study On The Thermal Conductivity Of Nanofluids, Jacopo Buongiorno, David C. Venerus, Naveen Prabhat, Thomas Mckrell, Jessica Townsend, Rebecca J. Christianson, Yuriv V. Tolmachev, Pawel Keblinski, Lin-Wen Hu, Jorge L. Alvarado, In Cheol Bang, Sandra W. Bishnoi, Marco Bonetti, Frank Botz, Anselmo Cecere, Yun Chang, Gang Chen, Haisheng Chen, Sung Jae Chung, Minking K. Chyu, Sarit K. Das, Roberto Di Paola, Yulong Ding, Frank Dubois, Grzegorz Dzido, Jacob Eapen, Werner Escher, Denis Funfschilling, Quentin Galand, Jinwei Gao, Patricia E. Gharagozloo, Kenneth E. Goodson, Jorge Gustavo Gutierrez, Haiping Hong, Mark Horton, Kyo Sik Hwang, Carlo S. Iorio, Seok Pil Jang, Andrzej B. Jarzebski, Yiran Jiang, Stephan Kabelac, Liwen Jin, Aravind Kamath, Mark A. Kedzierski, Lim Geok Kieng, Chongyoup Kim, Ji-Hyun Kim, Seokwon Kim, Seung Hyun Lee, Kai Choong Leong, Indranil Manna, Bruno Michel, Rui Ni, Hrishikesh E. Patel, John Philip, Dimos Poulikakos, Cecil Reynaud, Raffaele Savino, Pawan K. Singh, Pengxiang Song, Thirumalachari Sundararajan, Elena Timofeeva, Todd Tritcak, Aleksandr N. Turanov, Stefan Van Vaerenbergh, Dongsheng Wen, Sanjeeva Witharana, Chun Yang, Wei-Hsun Yeh, Xiao-Zheng Zhao, Sheng-Qi Zhou Dec 2011

A Benchmark Study On The Thermal Conductivity Of Nanofluids, Jacopo Buongiorno, David C. Venerus, Naveen Prabhat, Thomas Mckrell, Jessica Townsend, Rebecca J. Christianson, Yuriv V. Tolmachev, Pawel Keblinski, Lin-Wen Hu, Jorge L. Alvarado, In Cheol Bang, Sandra W. Bishnoi, Marco Bonetti, Frank Botz, Anselmo Cecere, Yun Chang, Gang Chen, Haisheng Chen, Sung Jae Chung, Minking K. Chyu, Sarit K. Das, Roberto Di Paola, Yulong Ding, Frank Dubois, Grzegorz Dzido, Jacob Eapen, Werner Escher, Denis Funfschilling, Quentin Galand, Jinwei Gao, Patricia E. Gharagozloo, Kenneth E. Goodson, Jorge Gustavo Gutierrez, Haiping Hong, Mark Horton, Kyo Sik Hwang, Carlo S. Iorio, Seok Pil Jang, Andrzej B. Jarzebski, Yiran Jiang, Stephan Kabelac, Liwen Jin, Aravind Kamath, Mark A. Kedzierski, Lim Geok Kieng, Chongyoup Kim, Ji-Hyun Kim, Seokwon Kim, Seung Hyun Lee, Kai Choong Leong, Indranil Manna, Bruno Michel, Rui Ni, Hrishikesh E. Patel, John Philip, Dimos Poulikakos, Cecil Reynaud, Raffaele Savino, Pawan K. Singh, Pengxiang Song, Thirumalachari Sundararajan, Elena Timofeeva, Todd Tritcak, Aleksandr N. Turanov, Stefan Van Vaerenbergh, Dongsheng Wen, Sanjeeva Witharana, Chun Yang, Wei-Hsun Yeh, Xiao-Zheng Zhao, Sheng-Qi Zhou

Jessica Townsend

This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (±10% or less) about ...


A Benchmark Study On The Thermal Conductivity Of Nanofluids, Jacopo Buongiorno, David Venerus, Naveen Prabhat, Thomas Mckrell, Jessica Townsend, Rebecca Christianson, Yuriv Tolmachev, Pawel Keblinski, Lin-Wen Hu, Jorge Alvarado, In Cheol Bang, Sandra Bishnoi, Marco Bonetti, Frank Botz, Anselmo Cecere, Yun Chang, Gang Chen, Haisheng Chen, Sung Jae Chung, Minking Chyu, Sarit Das, Roberto Di Paola, Yulong Ding, Frank Dubois, Grzegorz Dzido, Jacob Eapen, Werner Escher, Denis Funfschilling, Quentin Galand, Jinwei Gao, Patricia Gharagozloo, Kenneth Goodson, Jorge Gutierrez, Haiping Hong, Mark Horton, Kyo Sik Hwang, Carlo Iorio, Seok Pil Jang, Andrzej Jarzebski, Yiran Jiang, Stephan Kabelac, Liwen Jin, Aravind Kamath, Mark Kedzierski, Lim Geok Kieng, Chongyoup Kim, Ji-Hyun Kim, Seokwon Kim, Seung Hyun Lee, Kai Choong Leong, Indranil Manna, Bruno Michel, Rui Ni, Hrishikesh Patel, John Philip, Dimos Poulikakos, Cecil Reynaud, Raffaele Savino, Pawan Singh, Pengxiang Song, Thirumalachari Sundararajan, Elena Timofeeva, Todd Tritcak, Aleksandr Turanov, Stefan Van Vaerenbergh, Dongsheng Wen, Sanjeeva Witharana, Chun Yang, Wei-Hsun Yeh, Xiao-Zheng Zhao, Sheng-Qi Zhou Dec 2011

A Benchmark Study On The Thermal Conductivity Of Nanofluids, Jacopo Buongiorno, David Venerus, Naveen Prabhat, Thomas Mckrell, Jessica Townsend, Rebecca Christianson, Yuriv Tolmachev, Pawel Keblinski, Lin-Wen Hu, Jorge Alvarado, In Cheol Bang, Sandra Bishnoi, Marco Bonetti, Frank Botz, Anselmo Cecere, Yun Chang, Gang Chen, Haisheng Chen, Sung Jae Chung, Minking Chyu, Sarit Das, Roberto Di Paola, Yulong Ding, Frank Dubois, Grzegorz Dzido, Jacob Eapen, Werner Escher, Denis Funfschilling, Quentin Galand, Jinwei Gao, Patricia Gharagozloo, Kenneth Goodson, Jorge Gutierrez, Haiping Hong, Mark Horton, Kyo Sik Hwang, Carlo Iorio, Seok Pil Jang, Andrzej Jarzebski, Yiran Jiang, Stephan Kabelac, Liwen Jin, Aravind Kamath, Mark Kedzierski, Lim Geok Kieng, Chongyoup Kim, Ji-Hyun Kim, Seokwon Kim, Seung Hyun Lee, Kai Choong Leong, Indranil Manna, Bruno Michel, Rui Ni, Hrishikesh Patel, John Philip, Dimos Poulikakos, Cecil Reynaud, Raffaele Savino, Pawan Singh, Pengxiang Song, Thirumalachari Sundararajan, Elena Timofeeva, Todd Tritcak, Aleksandr Turanov, Stefan Van Vaerenbergh, Dongsheng Wen, Sanjeeva Witharana, Chun Yang, Wei-Hsun Yeh, Xiao-Zheng Zhao, Sheng-Qi Zhou

Rebecca J. Christianson

This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (±10% or less) about ...


Effect Of Gold Content On The Microstructural Evolution Of Sac305 Solder Joints Under Isothermal Aging, Mike Powers, Jianbiao Pan, Julie Silk, Patrick Hyland Nov 2011

Effect Of Gold Content On The Microstructural Evolution Of Sac305 Solder Joints Under Isothermal Aging, Mike Powers, Jianbiao Pan, Julie Silk, Patrick Hyland

Jianbiao Pan

Au over Ni on Cu is a widely used printed circuit board (PCB) surface finish, under bump metallization (UBM), and component lead metallization. It is generally accepted that less than 3 wt.% Au in Sn-Pb solder joints inhibits formation of detrimental intermetallic compounds (IMC). However, the critical limit for Au content in Pb-free solder joints is not well established. Three surface-mount package platforms, one with a matte Sn surface finish and the others with Ni/Au finish, were soldered to Ni/Au-finished PCB using Sn-3.0Ag- 0.5Cu (SAC305) solder, in a realistic manufacturing setting. The assembled boards were divided ...


Persistence, Engagement, And Migration In Engineering Programs, Matthew Ohland, Sheri Sheppard, Gary Lichtenstein, Ozgur Eris, Debbie Chachra, Richard Layton Jun 2011

Persistence, Engagement, And Migration In Engineering Programs, Matthew Ohland, Sheri Sheppard, Gary Lichtenstein, Ozgur Eris, Debbie Chachra, Richard Layton

Debbie Chachra

Records from the Multiple-Institution Database forInvestigating Engineering Longitudinal Development indicatethat engineering students are typical of students in other majorswith respect to: persistence in major; persistence by gender andethnicity; racial/ethnic distribution; and grade distribution. Datafrom the National Survey of Student Engagement show that thissimilarity extends to engagement outcomes including course challenge,faculty interaction, satisfaction with institution, and overallsatisfaction. Engineering differs from other majors most notablyby a dearth of female students and a low rate of migration into themajor. Noting the similarity of students of engineering and othermajors with respect to persistence and engagement, we proposethat engagement is a precursor to ...


Instability Of Electrokinetic Microchannel Flows With Conductivity Gradients, Hao Lin, Brian D. Storey, Michael H. Oddy, Chuan-Hua Chen, Juan G. Santiago Mar 2011

Instability Of Electrokinetic Microchannel Flows With Conductivity Gradients, Hao Lin, Brian D. Storey, Michael H. Oddy, Chuan-Hua Chen, Juan G. Santiago

Brian Storey

Electrokinetic flow is leveraged in a variety of applications, and is a key enabler of on-chip electrophoresis systems. An important sub-class of electrokinetic devices aim to pump and control electrolyte working liquids with spatial gradients in conductivity. These high-gradient flows can become unstable under the application of a sufficiently strong electric field. In this work the instability physics is explored using theoretical and numerical analyses, as well as experimental observations. The flow in a long, rectangular-cross-section channel is considered. A conductivity gradient is assumed to be orthogonal to the main flow direction, and an electric field is applied in the ...


Radial Response Of Individual Bubbles Subjected To Shock Wave Lithotripsy Pulses In Vitro, Thomas J. Matula, Paul R. Hilmo, Brian D. Storey, Andrew J. Szeri Mar 2011

Radial Response Of Individual Bubbles Subjected To Shock Wave Lithotripsy Pulses In Vitro, Thomas J. Matula, Paul R. Hilmo, Brian D. Storey, Andrew J. Szeri

Brian Storey

Direct measurements of individual bubble oscillations in lithotripsy fields have been performed using light-scattering techniques. Studies were performed with bubble clouds in gassy water as well as single levitated bubbles in degassed water. There is direct evidence that the bubble survives the inertial collapse, rebounding several times before breaking up. Bubble dynamics calculations agree well with the observations, provided that vapor trapping (a reduction in condensation during bubble collapse) is included. Furthermore, the afterbounces are dominated by vapor diffusion, not gas diffusion. Vapor trapping is important in limiting the collapse strength of bubbles, and in sonochemical activity. © 2010 American Institute ...