Ultrasonic wave dispersion and attenuation in a periodically two-layered medium
Bibliographic record
Abstract
In this work, we use numerical method to simulate wavefield propagation through a stratified cancellous bone model. A broadband Berlage pulse with a dominant frequency of 0.9 MHz was used to simulate an ultrasonic signal traveling through the model. Based on our preliminary work of elastic cases, the simulated signal displayed strong reverberation after the main transmitted arrival, demonstrating strong scattering within the stratification. The frequency spectrum shows "periodic" passing and stopping-bands. Within the primary passing band, the phase velocity decreases with frequency and the attenuation increases mildly with frequency. Within the stopping bands, the medium supports a constant phase velocity, with maximum attenuation but wave transmission is prohibited. The first cutoff frequency increases apparently with the decrease of the thickness of the two-layered period. It is interesting that these results could be quite accurately predicted using the approximation theory, which does not consider any multiple scattering within the stratification.
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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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".