Bibliographic record
Abstract
Flame acceleration within a channel is facilitated by repeating obstacles that generate turbulence. As the flame accelerates to supersonic velocities, it generates compression waves that coalesce to form a strong leading shock. This shock-flame complex continues to accelerate until it reaches a maximum velocity equal to the speed of sound in the combustion products; the complex is referred to as a fast-flame. Shock reflection driven onset of detonation may occur, characterized by an instantaneous jump in velocity to the theoretical ‘Chapman-Jouguet’ velocity. A more fundamental problem is the transition from a fast-flame to detonation without the presence of obstacles. In the current study, a 7.6 cm square ‘optical section’ housing a perforated plate was used to study the transition from fast-flame to detonation. A spark- and glow- plug served as ignition sources. The optical section had windows installed on its side and end walls so that Schlieren- and direct- photography could be captured. Soot foils were also utilized to record detonation cell structure. The fast-flame was generated by the passage of a detonation wave through the perforated plate, after which the transition to detonation could be studied. Gaseous fuel-oxygen mixtures of varying degrees of detonation stability over a wide range of pressures were tested. In low-pressure tests, delayed onset of detonation was observed, and detonation initiation sites were located at the channel walls indicating that flame-generated turbulence alone is not sufficient for the transition process. As pressure was increased, onset occurred immediately after the perforated plate at various locations across the channel cross-section, not strictly at the walls. For this abrupt ignition mode, transverse shock collisions played an important role in the transition to detonation.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".