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Oprisan, Ana; Garrabos, Yves; Lecoutre-Chabot, Carole; Beysens, Daniel

doi:10.1016/j.physa.2020.125293

Cited by 3 publications

(14 citation statements)

References 74 publications

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“…For image analysis, we cropped the most extensive possible rectangular area without including data markers. In this paper, we only discuss image processing results based on the last 300 µK thermal quench that stepped through the critical temperature [39,56,60]. The system was prepared at the critical density with the order parameter M = (ρ − ρ c )/ρ = 0.0 ± 0.02%.…”

Section: Methodsmentioning

confidence: 99%

“…The system was prepared at the critical density with the order parameter M = (ρ − ρ c )/ρ = 0.0 ± 0.02%. The 300 µK temperature quench through T c started the phase separation of the fluid (see [39,56,60] for a detailed description of the experimental procedure). Since the phase separation has begun during the last 300 µK thermal quench, we concluded that T c was somewhere between the upper (UP, i.e., T > T c ) and lower (DOWN, i.e., T < T c ) plateaus.…”

Section: Methodsmentioning

confidence: 99%

“…The density fluctuations were visualized through light transmission normal to the sapphire windows using a He-Ne laser with 632.8 nm wavelength and about 100 µW maximum power (see also [60] for a detailed description). Laser stability after 1 h was estimated to be better than 0.3 %.…”

Section: Methodsmentioning

confidence: 99%

“…All images for the DOWN region were recorded with the focal plane at the center of the cell. The full description of the experiment is presented elsewhere [55,56,60].…”

Section: Methodsmentioning

confidence: 99%

“…We use a new data-driven method for multi-scale analysis of critical fluctuations. The method (IMF) and one residual quantity [60]. We probe the fractal nature of critical fluctuations by separating spatial scales with the BEMD method followed by (1) morphological analysis and…”

Section: Bidimensional Empiric Mode Decomposition (Bemd)mentioning

confidence: 99%

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Density fluctuation analysis very near above and below critical point using morphological and spatiotemporal information

Oprisan

Garrabos

et al. 2021

Eur. Phys. J. Plus

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We investigate the fractal nature of critical fluctuations in sulfur hexafluoride (SF 6 ) under microgravity conditions. For this purpose, we use the Bidimensional Empiric Mode Decomposition (BEMD) approach to separate the spatial scales of fluctuations in orthogonal Independent Mode Functions (IMFs). Statistical analysis of three morphology measures (area, eccentricity, and orientation of convex objects in recorded images) across different IMFs shows that critical fluctuations obey power-laws across multiple spatial scales.We also perform a spatiotemporal analysis of fluctuations by extracting one line of pixels from each image and creating a temporal stack from successive images, or "waterfalls."The spatiotemporal section analysis along the spatial direction reveals multiple spatial scales present in the original fluctuating image. The analysis of the "waterfalls" along the temporal direction identifies a common power-law temporal behavior across all spatial scales. Our results show that critical fluctuations very near critical temperature (T c ) have a fractal structure captured by power-laws with multiple critical exponents. The morphology analysis shows that very near T c , the fluctuating domains are mostly spherical with some anisotropy.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…All images for the DOWN region were recorded with the focal plane at the center of the cell. The full description of the experiment is presented elsewhere [55,56,60].…”

Section: Methodsmentioning

confidence: 99%

Section: Bidimensional Empiric Mode Decomposition (Bemd)mentioning

confidence: 99%

See 3 more Smart Citations

Density fluctuation analysis very near above and below critical point using morphological and spatiotemporal information

Oprisan

Garrabos

et al. 2021

Eur. Phys. J. Plus

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Isobaric heat capacity of carbon dioxide at critical pressure: Singular thermodynamic functions as multiply broken power laws

Tomaschitz¹

2023

Physica A: Statistical Mechanics and its Applications

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Transport Properties of Critical Sulfur Hexafluoride From Multiscale Analysis of Density Fluctuations

Oprisan

Morgado²,

Dorf³

et al. 2022

Front. Space Technol.

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Density fluctuations near critical points have a wide range of sizes limited only by the boundaries of the enclosing container. How would a fluctuating image near the critical point look if we could break it into disjoint spatial scales, like decomposing white light into narrow-band, monochromatic waves? What are the scaling laws governing each spatial scale? How are the relaxation times of fluctuations at each spatial scale related to the dynamics of fluctuations in the original image? Fluctuations near the critical point of pure fluids lead to different patterns of phase separation, which has a significant influence on the materials’ properties. Due to the diverging compressibility of pure fluids near the critical temperature, the critical phase collapses under its weight on Earth. It limits both the spatial extent of fluctuations and their duration. In microgravity, the buoyancy and convection are suppressed, and the critical state can be observed much closer to the critical point for a more extended period. Local density fluctuations induce light intensity fluctuations (the so-called “critical opalescence”), which we recorded for a sulfur hexafluoride (SF6) sample near the critical point in microgravity using the ALI (Alice Like Instrumentation insert) of the DECLIC (Dispositif pour l’Etude de la Croissance et des Liquides Critiques) facility on the International Space Station (ISS). From the very short (approximately 173 s total recording) data set very near, within 200 μK, the critical temperature, we determined the effective diffusion coefficient for fluctuations of different sizes. For transient and non-stationary data recorded very near the critical point immediately after a thermal quench that steps through critical temperature, we separated fluctuations of various sizes from the original images using the Bidimensional Empirical Mode Decomposition (BEMD) technique. Orthogonal and stationary Intrinsic Mode Function (IMF) images were analyzed using the Fourier-based Dynamic Differential Microscopy (DDM) method to extract the correlation time of fluctuations. We found that a single power-law exponent represented each IMF’s structure factor. Additionally, each Intermediate Scattering Function (ISF) was determined by fluctuations’ unique relaxation time constant. We found that the correlation time of fluctuations increases with IMF’s order, which shows that small size fluctuations have the shortest correlation time. Estimating thermophysical properties from short data sets affected by transient phenomena is possible within the BEMD framework

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Multiscale empirical mode decomposition of density fluctuation images very near above and below the critical point of SF6

Cited by 3 publications

References 74 publications

Density fluctuation analysis very near above and below critical point using morphological and spatiotemporal information

Density fluctuation analysis very near above and below critical point using morphological and spatiotemporal information

Isobaric heat capacity of carbon dioxide at critical pressure: Singular thermodynamic functions as multiply broken power laws

Transport Properties of Critical Sulfur Hexafluoride From Multiscale Analysis of Density Fluctuations

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