Characterization of Surface-Breaking Tight Cracks Using Laser-Ultrasonic Shadowing
Bibliographic record
Abstract
A laser‐ultrasonic method based on the shadowing effect is used for sizing and locating surface‐breaking tight cracks in metals. The two laser spots are separated by a fixed distance to detect ultrasound propagating at oblique incidence with respect to the sample surface. The laser spots are scanned along the same line across the path of cracks on the cracking surface or opposite surface. The amplitude of the longitudinal or shear waves specularly reflected from the backwall is extracted from each signal to construct an amplitude profile. In the presence of a crack, the profile shows regions of reduced amplitude due to shadowing of the direct or reflected beam from the backwall. The sharp amplitude drop and the gentle signal recovery observed are well predicted by a model of crack tip diffraction. The crack depth can be simply determined by considering the immediate vicinity of the amplitude drop. Results are shown on a stainless steel sample having a variable depth slot as well as on a sample containing actual surface‐breaking tight cracks having widths of less than 30 μm.
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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 | 0.000 |
| 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".