Time and frequency analysis of air bubbles injected underwater
Bibliographic record
Abstract
The acoustic signal generated by vibrating air bubbles injected in water allows for the passive detection of underwater sources such as divers and gas leaking from pipes. In this paper, an experimental analysis of the time and frequency characteristics of these signals is presented. The decaying acoustic signal of a single bubble created by nozzles of different diameters is described and extended to a train of bubbles from an array of nozzles. The oscillatory motion of the bubble surface generates an acoustic signal that has a damped sinusoidal characteristic. The spectrum of this waveform has a fundamental frequency and several harmonics. Therefore, the effect of ambient noise can be suppressed using a suitable band pass filter with a center frequency equal to the bubble fundamental frequency. It is shown that the acoustic signal generated by these bubbles can be utilized for passive detection and remote sensing (including depth estimation). Experimental data from a Saanich inlet experiment is analyzed to obtain realistic results. These results are compared with the theoretical analysis.
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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 | 0.000 | 0.000 |
| 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".