Nonlinear behaviour of lossy acoustic black holes
Bibliographic record
Abstract
Sound absorption properties of acoustic black holes are studied for high pressure amplitudes.The absorbers consist of thin circular plates, each with a central perforation, separated by annular air cavities.Radius of the perforation of each plate depends on its position thus forming a central channel with a gradually decreasing radius.In our previous work, a linear equivalent fluid model accounting for the variations of the effective properties of air inside this channel was developed.However, the FEM simulations show that flow resistivity of the structure increases with the flow rate according to Forchheimer's law.This indicates that an extension of the model is necessary for the incident waves of high amplitude.In the current work, the measurements are performed for continuous high amplitude sound.A specially designed impedance tube is used for the experiments.The measurements and modelling show that the nonlinearity of acoustic black holes affects mostly the low frequencies.At higher frequencies, the absorption performance is weakly affected by the nonlinearity.This opens a possibility of using these structures as effective broadband absorbers of high amplitude sound.
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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 | 0.000 | 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) | 0.001 | 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".