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 Liquid surfaces (2)
 Atomic force microscopy (2)
 Merging (2)
 Holoimage (2)
 Surface dynamics (2)

 Heat transfer (1)
 Adhesion (1)
 Calibration (1)
 Inerface structures (1)
 Molecular dynamics (1)
 Attractors (1)
 Lawrence Berkeley National Laboratory (1)
 Rheology and fluid dynamics (1)
 Liquid solid interfaces (1)
 Quasicrystals (1)
 Measurement (1)
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 Structured light (1)
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 Registration (1)
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Articles 1  10 of 10
FullText Articles in Mechanical Engineering
Unsteady Nanoscale Thermal Transport Across A SolidFluid Interface, Ganesh Balasubramanian, Soumik Banerjee, Ishwar K. Puri
Unsteady Nanoscale Thermal Transport Across A SolidFluid Interface, Ganesh Balasubramanian, Soumik Banerjee, Ishwar K. Puri
Ganesh Balasubramanian
We simulate unsteady nanoscale thermal transport at a solidfluidinterface by placing cooler liquidvapor Ar mixtures adjacent to warmer Fe walls. The equilibration of the system towards a uniform overall temperature is investigated using nonequilibrium molecular dynamics simulations from which the heat flux is also determined explicitly. The Ar–Fe intermolecular interactions induce the migration of fluid atoms into quasicrystallineinterfacial layers adjacent to the walls, creating vacancies at the migration sites. This induces temperature discontinuities between the solidlikeinterfaces and their neighboring fluid molecules. The interfacial temperature difference and thus the heat flux decrease as the system equilibrates over time. The averaged ...
Sum Frequency Generation Vibrational Spectroscopy Of Pyridine Hydrogenation On Platinum Nanoparticles, Kaitlin M. Bratlie, Kyriakos Komvopoulos, Gabor A. Somorjai
Sum Frequency Generation Vibrational Spectroscopy Of Pyridine Hydrogenation On Platinum Nanoparticles, Kaitlin M. Bratlie, Kyriakos Komvopoulos, Gabor A. Somorjai
Kaitlin M. Bratlie
Pyridine hydrogenation in the presence of a surface monolayer consisting of cubic Pt nanoparticles stabilized by tetradecyltrimethylammonium bromide (TTAB) was investigated by sum frequency generation (SFG) vibrational spectroscopy using total internal reflection (TIR) geometry. TIRSFG spectra analysis revealed that a pyridinium cation (C5H5NH+) forms during pyridine hydrogenation on the Pt nanoparticle surface, and the NH group in the C5H5NH+ cation becomes more hydrogen bound with the increase of the temperature. In addition, the surface coverage of the cation decreases with the increase of the temperature. An important contribution of this study is the in situ identification of reaction intermediates adsorbed ...
ThreeDimensional Data Merging Using Holoimage, Song Zhang, ShingTung Yau
ThreeDimensional Data Merging Using Holoimage, Song Zhang, ShingTung Yau
Song Zhang
Threedimensional data merging is vital for fullfield threedimensional (3D) shape measurement. All 3D range data patches, acquired from either different sensors or the same sensor in different viewing angles, have to be merged into a single piece to facilitate future data analysis. A novel method for 3D data merging using Holoimage is proposed. Similar to the 3D shape measurement system using a phaseshifting method, Holoimage is a phaseshifting–based computer synthesized fringe image. The 3D information is retrieved from Holoimage using a phaseshifting method. If two patches of 3D data with overlapping areas are rendered by OpenGL, the overlapping areas ...
ThreeDimensional Shape Measurement Using A Structured Light System With Dual Cameras, Song Zhang, ShingTung Yau
ThreeDimensional Shape Measurement Using A Structured Light System With Dual Cameras, Song Zhang, ShingTung Yau
Song Zhang
A structured light system for threedimensional shape measurement with single camera has the shortcoming of camera occlusion. To alleviate this problem, this paper introduces a structured light system with dual cameras for threedimensional shape measurement. We discuss (1) system description, (2) system calibration, (3) threedimensional data registration using the iterative closestpoint (ICP) algorithm, and (4) threedimensional data merging using holoimage. The principle of the system is introduced, and experiments are presented to verify its performance.
MeltDispersion Mechanism For Fast Reaction Of Aluminum Particles: Extension For Micron Scale Particles And Fluorination, Valery I. Levitas, Michelle L. Pantoya, Kyle W. Watson
MeltDispersion Mechanism For Fast Reaction Of Aluminum Particles: Extension For Micron Scale Particles And Fluorination, Valery I. Levitas, Michelle L. Pantoya, Kyle W. Watson
Valery I. Levitas
The theoretically predicted relationship for the relative flame rate versus relative particle size based on the melt dispersion mechanism (MDM), which was previously confirmed for oxidation of 40–120nm diameter aluminum particles, is found to be in agreement with experiments for 1–3μm diameter Al particles and fluorination. The main physical parameters for MDM (pressure in molten particle, cavitation threshold, and nanoclusters’ velocity) have been estimated for micron scale particles. The results suggest parameters that could be controlled during particle synthesis that would enable micron scale Al particles to react and achieve the performance of nanoscale Al particles.
Melt Dispersion Versus Diffusive Oxidation Mechanism For Aluminum Nanoparticles: Critical Experiments And Controlling Parameters, Valery I. Levitas, Michelle L. Pantoya, Birce Dikici
Melt Dispersion Versus Diffusive Oxidation Mechanism For Aluminum Nanoparticles: Critical Experiments And Controlling Parameters, Valery I. Levitas, Michelle L. Pantoya, Birce Dikici
Valery I. Levitas
Critical experiments were performed on Al and MoO3 thermites. The diameter and alumina shell thickness of the Alnanoparticles were varied, and flame propagation velocities were measured. The results strongly support the meltdispersion mechanism and contradict the diffusionoxidation mechanism. The parameters that control the oxidation rate and flame velocity are justified and directions for the synthesis of Alnanoparticles (which are opposite to the current directions based on diffusionoxidation) are suggested. An equation for the flame velocity versus Alnanoparticle geometrical parameters, thermomechanical properties, and synthesis parameters is formulated.
The Dissipated Power In Atomic Force Microscopy Due To Interactions With A Capillary Fluid Layer, Nicole N. Hashemi, M.R. Paul, H. Dankowicz, W. Jhe
The Dissipated Power In Atomic Force Microscopy Due To Interactions With A Capillary Fluid Layer, Nicole N. Hashemi, M.R. Paul, H. Dankowicz, W. Jhe
Nastaran Hashemi
We study the power dissipated by the tip of an oscillating micronscale cantilever as it interacts with a sample using a nonlinear model of the tipsurface force interactions that includes attractive, adhesive, repulsive, and capillary contributions. The force interactions of the model are entirely conservative and the dissipated power is due to the hysteretic nature of the interaction with the capillary fluid layer. Using numerical techniques tailored for nonlinear and discontinuous dynamical systems we compute the exact dissipated power over a range of experimentally relevant conditions. This is accomplished by computing precisely the fraction of oscillations that break the fluid ...
The Nonlinear Dynamics Of Tapping Mode Atomic Force Microscopy With Capillary Force Interactions, Nicole N. Hashemi, H. Dankowicz, M.R. Paul
The Nonlinear Dynamics Of Tapping Mode Atomic Force Microscopy With Capillary Force Interactions, Nicole N. Hashemi, H. Dankowicz, M.R. Paul
Nastaran Hashemi
We study the nonlinear dynamics of a tapping mode atomic force microscope with tipsurface interactions that include attractive, repulsive, and capillary force contributions using numerical techniques tailored for hybrid or discontinuous dynamical systems that include forwardtime simulation with event handling and numerical pseudoarclength continuation. We find four branches of periodic solutions that are separated by windows of complex and irregular dynamics. The branches of periodic solutions end where the cantilever comes into grazing contact with event surfaces in state space, corresponding to the onset of capillary interactions and the onset of repulsive forces associated with contact. These windows of irregular ...
Finite Element Modeling Of Dynamics Of Martensitic Phase Transitions, Alexander V. Idesman, Joon Yeoun Cho, Valery I. Levitas
Finite Element Modeling Of Dynamics Of Martensitic Phase Transitions, Alexander V. Idesman, Joon Yeoun Cho, Valery I. Levitas
Valery I. Levitas
A finite element approach is suggested for the modeling of the dynamics of multivariant martensitic phase transitions (PTs) in elasticmaterials at the nanoscale in the three dimensional (3D) case. The model consists of a coupled system of the Ginzburg–Landau equations for transformation strainrelated order parameters and dynamic elasticity equations. Thermodynamic potential [V. Levitas and D. Preston, Phys. Rev. B66, 134206 (2002)] that captures the main features of macroscopic stressstrain curves is used. The evolution of multivariant microstructure in a 3D specimen for cubic to tetragonal PT in a NiAl alloy is modeled with dynamic and static formulations. The numerical ...
Absolute PhaseAssisted ThreeDimensional Data Registration For A DualCamera Structured Light System, Song Zhang, ShingTung Yau
Absolute PhaseAssisted ThreeDimensional Data Registration For A DualCamera Structured Light System, Song Zhang, ShingTung Yau
Song Zhang
For a threedimensional shape measurement system with a single projector and multiple cameras, registering patches from different cameras is crucial. Registration usually involves a complicated and timeconsuming procedure. We propose a new method that can robustly match different patches via absolute phase without significantly increasing its cost. For y and z coordinates, the transformations from one camera to the other are approximated as thirdorder polynomial functions of the absolute phase. The x coordinates involve only translations and scalings. These functions are calibrated and only need to be determined once. Experiments demonstrated that the alignment error is within RMS 0.7 ...