Bibliographic record
Abstract
Sand bars having spacing equal to half the surface wavelength may be formed by the action of partially standing waves on an erodible bed. Here the stages of development of a patch of bars has been investigated in a wave tank, using rapid, accurate, ultra-sonic detection systems to monitor both the changing bed profile and the evolving surface wavefield. Initially, small-scale ripples formed on a (flattened) bed surface. These ripples varied in size according to position in the wave envelope, and had asymmetrical profiles due to asymmetry in the near-bed oscillatory motion. Vortex shedding from the ripples gave rise to regions of net sediment accumulation (bar crests) and erosion (troughs) linked to position in the wave envelope. The bars formed with wavelength satisfying the Bragg condition and with bar crests positioned downwave of the antinodes of elevation. As expected, this produced an increase in the overall reflection coefficient of the bar patch as the bars grew in height. The presence of the small-scale ripples had only a minor effect on the reflection coefficient, the flow being essentially inviscid away from the boundaries of the motion and the ripple wavelength being far smaller than the surface wavelength. However, the ripples played an important role in dissipating wave energy in the tank, wave dissipation factors being 3 or 4 times larger than equivalent values for laminar flow above a smooth bed. The present observations of the resonant interaction between surface waves and an erodible bed are believed to be the most detailed and accurate to have been reported to date.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.004 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.004 | 0.003 |
| Science and technology studies | 0.003 | 0.004 |
| Scholarly communication | 0.006 | 0.007 |
| Open science | 0.005 | 0.005 |
| Research integrity | 0.009 | 0.003 |
| Insufficient payload (model declined to judge) | 0.990 | 0.993 |
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; the direct Gemma label and the distilled Codex classifier agree on what is shown here.
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".