Anomalous diffusion of multiply scattered ultrasound in a two-component disordered medium
Bibliographic record
Abstract
Measurements of multiply-scattered wave transport allow the characterization of heterogeneous media and may reveal anomalous wave properties. When a wave propagates through a sufficiently disordered medium, it will undergo many scattering events. This may lead to diffusive transport or even, in highly disordered media, to localized behavior in which transport comes to a halt. These two regimes can be distinguished by measuring the evolution of the transverse intensity profile when point-like ultrasonic pulse is incident on the opposite side of a slab-shaped sample. In the case of diffusive propagation, the profile width grows without limit as the square root of time, while for localized waves, the width reaches a saturation value at long times due to the trapping of the waves in the medium. In our experiment, the sample consists of aluminum beads randomly packed in silicone oil. Contrary to expectations, the width goes through a maximum as a function of time and varies slowly afterwards. This novel behavior may be due to the existence of two coupled modes of propagation: a fast component travelling through the liquid and a slower component traveling through the bead network. The resonances of the beads influence strongly the propagation inside the solid network.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".