Sound velocity and attenuation measurements of perfluorocarbon liquids using photoacoustic methods
Bibliographic record
Abstract
A method to measure the phase velocity and attenuation of liquids over a frequency range of 100-1000 MHz using a photoacoustic method is presented. A pulsed laser directed at a thin gold or ink layer was used to create a broadband ultrasonic wave and was used as the source. An ultrasound transducer (375 or 750 MHz center frequency) positioned above the source was used as the receiver. The phase and amplitude spectra of signals transmitted through a liquid between the photoacoustic source and ultrasound receiver were used to determine the phase velocity and attenuation as a function of frequency. The method was first validated using water, ethanol and castor oil. The phase velocity and attenuation were similar to published values. Water and ethanol showed no dispersion with frequency, while castor oil increased from 1508 m/s at 200 MHz to 1561 m/s at 700 MHz. Three perfluorocarbon (PFC) liquids (perfluorohexane, perfluoroheptane and FC-77) were then measured. The phase velocity was 480, 516 and 557 m/s at 200 MHz for perfluorohexane, perfluoroheptane and FC-77, respectively, and increased by approximately 1.5% at 700 MHz. The attenuation was similar for all three PFC liquids at 0.352f1.56dB/cm/MHzn.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".