scholarly journals Suitability of the echo-time-shift method as laboratory standard for thermal ultrasound dosimetry

2017 ◽  
Author(s):  
Tina Fuhrmann ◽  
Olga Georg ◽  
Julian Haller ◽  
Klaus-Vitold Jenderka
Keyword(s):  
Time Shift ◽  
Shift Method ◽  
Echo Time

scholarly journals Effect of Solid Particles on Droplet Size Applying the Time-Shift Method for Spray Investigation

2020 ◽  
Vol 10 (21) ◽  
pp. 7615
Author(s):  
Simon Wachter ◽  
Tobias Jakobs ◽  
Thomas Kolb
Keyword(s):  
Droplet Size ◽  
High Speed ◽  
Solid Particles ◽  
Time Shift ◽  
Pure Liquid ◽  
Sauter Mean Diameter ◽  
Shift Method ◽  
Spray Formation ◽  
Primary Breakup ◽  
Shift Effect

This study investigated the influence of solid particles on primary breakup and resulting droplet size for different process parameters. Two sets of Newtonian fluids (each consisting of one pure liquid and one suspension at the same respective viscosity) were used, for isolated investigation of solid particles on spray formation independent of liquid viscosity. The spray was recorded by a high-speed camera and a SpraySpy® system based on the time-shift effect, while a commonly used Spraytec® laser diffraction analyzer was employed for validation. An external-mixing twin-fluid atomizer was operated at different gas velocities and corresponding GLR at constant liquid mass flow. For the investigated suspensions an increased Sauter mean diameter was detected, compared to the pure liquids with identical dynamic viscosity. This effect was explained by the tensile strength stabilizing the suspension droplets.

Integration of Atomistic Simulation with Experiment Using Time−Temperature Superposition for a Cross-Linked Epoxy Network

2019 ◽  
Author(s):  
Ketan Khare ◽  
Frederick R. Phelan Jr.
Keyword(s):  
Master Curve ◽  
Glassy State ◽  
Superposition Principle ◽  
Quantitative Comparison ◽  
Time Shift ◽  
Data Sets ◽  
Epoxy Network ◽  
Temperature Superposition ◽  
Time Temperature Superposition ◽  
Time Temperature Superposition Principle

<a></a><a>Quantitative comparison of atomistic simulations with experiment for glass-forming materials is made difficult by the vast mismatch between computationally and experimentally accessible timescales. Recently, we presented results for an epoxy network showing that the computation of specific volume vs. temperature as a function of cooling rate in conjunction with the time–temperature superposition principle (TTSP) enables direct quantitative comparison of simulation with experiment. Here, we follow-up and present results for the translational dynamics of the same material over a temperature range from the rubbery to the glassy state. Using TTSP, we obtain results for translational dynamics out to 10<sup>9</sup> s in TTSP reduced time – a macroscopic timescale. Further, we show that the mean squared displacement (MSD) trends of the network atoms can be collapsed onto a master curve at a reference temperature. The computational master curve is compared with the experimental master curve of the creep compliance for the same network using literature data. We find that the temporal features of the two data sets can be quantitatively compared providing an integrated view relating molecular level dynamics to the macroscopic thermophysical measurement. The time-shift factors needed for the superposition also show excellent agreement with experiment further establishing the veracity of the approach</a>.

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