scholarly journals Oscillation Mode Variability in Evolved Compact Pulsators from Kepler Photometry. II. Comparison of Modulation Patterns between Raw and Corrected Flux

2021 ◽  
Vol 921 (1) ◽  
pp. 37
Author(s):  
Weikai Zong ◽  
Stéphane Charpinet ◽  
Gérard Vauclair
Keyword(s):  
Oscillation Mode

Bouncing on thin air: how squeeze forces in the air film during non-wetting droplet bouncing lead to momentum transfer and dissipation

2015 ◽  
Vol 776 ◽  
pp. 531-567 ◽  
Author(s):  
Jolet de Ruiter ◽  
Rudy Lagraauw ◽  
Frieder Mugele ◽  
Dirk van den Ende
Keyword(s):  
Oscillation Mode ◽  
Interference Microscopy ◽  
Droplet Motion ◽  
Solid Substrates ◽  
Long Time ◽  
Lift Off ◽  
Continuous Presence ◽  
Air Film ◽  
Single Oscillation

Millimetre-sized droplets are able to bounce multiple times on flat solid substrates irrespective of their wettability, provided that a micrometre-thick air layer is sustained below the droplet, limiting $\mathit{We}$ to ${\lesssim}4$. We study the energy conversion during a bounce series by analysing the droplet motion and its shape (decomposed into eigenmodes). Internal modes are excited during the bounce, yet the viscous dissipation associated with the in-flight oscillations accounts for less than 20 % of the total energy loss. This suggests a significant contribution from the bouncing process itself, despite the continuous presence of a lubricating air film below the droplet. To study the role of this air film we visualize it using reflection interference microscopy. We quantify its thickness (typically a few micrometres) with sub-millisecond time resolution and ${\sim}30~\text{nm}$ height resolution. Our measurements reveal strong asymmetry in the air film shape between the spreading and receding phases of the bouncing process. This asymmetry is crucial for effective momentum reversal of the droplet: lubrication theory shows that the dissipative force is repulsive throughout each bounce, even near lift-off, which leads to a high restitution coefficient. After multiple bounces the droplet eventually hovers on the air film, while continuously experiencing a lift force to sustain its weight. Only after a long time does the droplet finally wet the substrate. The observed bounce mechanism can be described with a single oscillation mode model that successfully captures the asymmetry of the air film evolution.

scholarly journals Oscillation mode linewidths and heights of 23 main-sequence stars observed byKepler

2014 ◽  
Vol 566 ◽  
pp. A20 ◽  
Author(s):  
T. Appourchaux ◽  
H. M. Antia ◽  
O. Benomar ◽  
T. L. Campante ◽  
G. R. Davies ◽  
...  
Keyword(s):  
Main Sequence ◽  
Oscillation Mode ◽  
Main Sequence Stars

scholarly journals Mold Nonsinusoidal Oscillation Mode and Its Effect on Slag Infiltration for Lubrication and Initial Shell Growth during Steel Continuous Casting

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 418 ◽  
Author(s):  
Xiaobo Yan ◽  
Boran Jia ◽  
Qiangqiang Wang ◽  
Shengping He ◽  
Qian Wang
Keyword(s):  
Liquid Film ◽  
Molten Steel ◽  
Liquid Slag ◽  
Shell Growth ◽  
Oscillation Mode ◽  
Quantitative Prediction ◽  
Multiphase Model ◽  
Obvious Effect ◽  
Mold Slag ◽  
Mold Oscillation

The effect of nonsinusoidal oscillation at different modification ratios (α) on slag lubrication was investigated during mold oscillation. A validated and reliable multiphase model was employed, which involved flow and solidification of the molten steel and mold slag. The main results revealed that a large amount of liquid slag at the entrance of the mold–strand channel reflowed into the slag pool at the middle of the negative strip period. The phenomenon was more distinct, with an increase in the modification ratio. The modification ratio had no obvious effect on the average thickness of the liquid film at different depths below the meniscus. A modification ratio of 0.5 caused less fluctuation of the transient liquid film. Quantitative prediction of slag consumption indicated that as the modification ratio increased from 0.2 to 0.5 to 0.8, the average values were 0.278, 0.286, and 0.279 kg/m2, respectively. Shell solidification and growth near the meniscus mainly occurred when the mold was descending, which not only depended on the heat flux, but also on the liquid slag flow, the pressure driven by slag rim, and the mold oscillation. Optimization of the modification ratio of nonsinusoidal oscillation could be an alternative to delay growth of the initial shell towards the molten steel. A modification ratio of 0.5 had the least robust shell tip at the meniscus, thereby reducing entrapment of inclusions and bubbles by the shell tip.

scholarly journals Asteroseismology of 36 Kepler subgiants – I. Oscillation frequencies, linewidths, and amplitudes

2020 ◽  
Vol 495 (2) ◽  
pp. 2363-2386 ◽  
Author(s):  
Yaguang Li ◽  
Timothy R Bedding ◽  
Tanda Li ◽  
Shaolan Bi ◽  
Dennis Stello ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Oscillation Mode ◽  
Monte Carlo Algorithm ◽  
Scaling Relations ◽  
Mass Dependence ◽  
Seismic Parameters ◽  
Theoretical Predictions ◽  
Mixed Modes ◽  
Oscillation Frequencies ◽  
Spectrum Model

ABSTRACT The presence of mixed modes makes subgiants excellent targets for asteroseismology, providing a probe for the internal structure of stars. Here we study 36 Kepler subgiants with solar-like oscillations and report their oscillation mode parameters. We performed a so-called peakbagging exercise, i.e. estimating oscillation mode frequencies, linewidths, and amplitudes with a power spectrum model, fitted in the Bayesian framework and sampled with a Markov chain Monte Carlo algorithm. The uncertainties of the mode frequencies have a median value of 0.180 μHz. We obtained seismic parameters from the peakbagging, analysed their correlation with stellar parameters, and examined against scaling relations. The behaviour of seismic parameters (e.g. Δν, νmax, ϵp) is in general consistent with theoretical predictions. We presented the observational p–g diagrams, namely γ1–Δν for early subgiants and ΔΠ1–Δν for late subgiants, and demonstrate their capability to estimate stellar mass. We also found a log g dependence on the linewidths and a mass dependence on the oscillation amplitudes and the widths of oscillation excess. This sample will be valuable constraints for modelling stars and studying mode physics such as excitation and damping.

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