Experimental Validation of the Length Correction Factor for Folded Quarter-Wavelength Resonators
Bibliographic record
Abstract
Quarter-wavelength acoustic metamaterials consist of multiple quarter wavelength resonators that are tuned to different resonance frequencies to create broadband sound absorption.To maintain a compact volume at low frequencies, these resonators are often folded.The impact of a fold on the resonance frequency of a quarterwavelength resonator has been investigated numerically in a previous study [1] and a length correction factor to account for these effects was also proposed.In this paper, the validity of this correction factor is assessed experimentally.To this end, several test samples are 3D printed using an FDM printer.Each sample consists of quarter-wavelength resonators with a single 90° bend and a resonance frequency between 1000 Hz and 2000 Hz.The absorption coefficient of each sample is measured in an impedance tube according to the ISO 10534-2 standard.The experimental results are then compared to the model.It is found that the analytical and experimental results show good agreement, which implies that the use of the proposed correction factor is justified.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.002 |
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".