Evolution of Ripple Field Architecture during Sediment Transport, as Measured by CT Scanning
Bibliographic record
Abstract
Despite the advent of ever more sophisticated technologies, the study of sediment transport remains highly relevant.Ongoing climate change adds urgency to the need to understand phenomena governing sediment transport.During sediment movement, the architecture of the sediment bed evolves (Nummedal et al., 1993;Allen and Posamentier, 1994;Van Wagoner, 1995).This chapter focuses on the fundamental processes involved in sediment transport and aims to define and characterize the evolution of the water-sediment mixture in a migrating sand ripple field under a stationary flow regime, from the flow surface to the base of the sediment bed.In an experimental sediment flume with attached computed tomography (CT)-scanner, the sediment density of a ripple field was studied at different phases of its architectural evolution using three-and four-dimensional X-ray scanning, under several flow regimes and with different grain sizes.This approach yielded a detailed understanding of the parameters involved in transport of sand-grade sediment. MethodsThis study used two hydraulic flumes.One was a vertical, closed-loop flume 3048 mm long and 1219 mm high designed by Teeter and Pankow (1989).The inner rectangular section of the flume (152 mm by 304 mm) passed through the mobile gantry of a computed tomography (CT)-scanner.The lower part of the tunnel was partly filled with a 30 mm-thick layer of C-109 Ottawa sand (0.37 mm grain size, with bulk dry density of 1.56 g•cm -³).The flow regime was adjusted by an electrical motor to 25 cm•s -1 and controlled by a Doppler flow meter (Controlotron 1010N).For more details of this apparatus, see Montreuil (2006).In this flume experiment, the volume element (voxel) chosen was 0.39 mm by 0.60 mm by 1.00 mm.Typical density profiles along the ripple bed were extracted from the CT-scanner measurement matrix of 512 x 512 x 512 voxels and a 305 x 305 x 200 mm volume.The second flume was an open acrylic flume (300 x 300 x 7000 mm) looped by a pump with 1.51 m 3 •min -1 capacity.The rectangular section of the flume (300 x 300 mm), passed through the mobile gantry of the CT-scanner (Fig. 1).The steady flow, measured by a Controlotron www.intechopen.com
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".