Transit time broadening: a pulsed doppler ultrasound perspective
Bibliographic record
Abstract
Many studies on transit time broadening have been performed to characterize its effect on the Doppler spectrum. However, the dependence of transit time broadening on an important pulsed Doppler ultrasound parameter - the range gate used for depth localization - has not been rigorously addressed. The purpose of this paper is to provide an analysis of how the range gate may contribute to transit time broadening from a pulsed Doppler perspective. Our analysis and simulation results show that the range gate can contribute to transit time broadening at small beam-flow angles. In particular, at such angles, the spectral broadening bandwidth is dependent on the effective axial length of the sample volume. On the other hand, at higher beam-flow angles, the spectral broadening bandwidth is dependent on ultrasound beam parameters such as local length and aperture size: a finding that is consistent with previous studies. Our analysis also shows that there exists a transition beam-flow angle at which the parameters governing transit time broadening undergo a significant change.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".