Measurements of the changing wave velocities of sand during the formation and dissociation of disseminated methane hydrate
Bibliographic record
Abstract
Abstract The formation and dissociation of methane hydrate within sediment can lead to large changes in wave velocities, which provide valuable insights into the processes involved in hydrate formation. These are of practical importance in geophysical characterization, as well as developing strategies for the future exploitation of methane hydrates. This paper presents changes in wave velocity, measured during hydrate formation, and subsequent dissociation, using the resonant column apparatus. Hydrate was formed under “drained” and “undrained” conditions. Drained specimens had free access to methane during formation, while for undrained specimens, methane content was fixed. Hydrate formation and dissociation were induced by changing the specimen temperature under constant effective stress. In excess of 20 determinations of shear wave and flexural wave velocity were carried out over a 9 h period, both during hydrate formation and dissociation. This time was sufficient to record almost all of the changes in wave velocity within a specimen. The exothermic nature of hydrate formation was clearly seen in the form of spikes in temperature measured at the base of the specimens. For all specimens, the relationship between wave velocity and degree of hydrate saturation was nonlinear and significantly different during formation and dissociation. The patterns observed suggest that hydrate morphology not only is important in controlling the ultimate wave velocities, at the end of formation, but has a significant impact on the rates of change of wave velocities during formation and dissociation. A conceptual model is presented to explain differences in observed behavior during formation and dissociation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".