Phase determination from atomically resolved images: physics-constrained deep data analysis through an unmixing approach
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Fast Fourier Transform↗
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Surface roughness in polycrystalline copper under cyclic thermal loading: FFT-based thermomechanical modelling with experimental verification for accelerator applications [Slides]
The copper chambers contain an electromagnetic field known as radiofrequency (RF) cavities. Accelerator cavities have superior surface finish with roughness, Ra, of about 0.05 to 0.1 µm. For reference, mirror finish is 0.8 μm.
36 MATERIALS SCIENCE↗
Three New EMP Analysis Methods [Slides]
Three analysis techniques are presented. One is a new method of doing spectrograms that gives full time resolution and optimum frequency resolution. Another is a method that uses the phase of the Fourier transform of the signal rather than the magnitude of narrow band receivers. With one FFT, one can obtain 1000’s of TOA-frequency pairs to fit to that are unaffected by any magnetic field that the signal encounter during propagation. The third method dechirps the signal in a manner that identifies the STEC and VTOA that finds when the signal has both ionospheric modes equally.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
The effect of contact severity on micropitting: Simulation and experiments
In this work, a numerical contact fatigue model combining the effects of rolling contact fatigue and wear has been developed based on mixed elastohydrodynamic lubrication (EHL) theory, continuum damage mechanics (CDM) and the Archard's wear law. A series of benchtop tests were conducted using a triple-contact test rig to study the influence of surface roughness, speed and load on micropitting. The proposed surface damage model was used to simulate the rolling-sliding line contact of surfaces having different surface topography. The film thickness, contact pressure and sub-surface stress were determined by solving the generalized Reynolds equation and using the well-developed discrete convolute and fast Fourier transformation (DC-FFT) method. The jump-in-cycle was assumed to evaluate the accumulated damage based on the tested fatigue life and sub-surface stress histories. Surface topography was updated by calculating the wear height with the Archard's wear equation. Results reveal that micropitting occurs under the combined effect of wear and contact fatigue. The micropitting rate increased then turn to decreased as the lambda ratio (lambda) increased. The contact pressure significantly affected the contact fatigue life and the micropitting rate.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗