Real Time Pulsed Eddy Current Detection of Cracks in F/A-18 Inner Wing Spar Using Discriminant Separation of Modified Principal Components Analysis Scores
Bibliographic record
Abstract
The aluminum inner wing spars of F/A-18 Hornet aircraft may undergo stress corrosion cracking along the spar between the fasteners that secure carbon-fiber/epoxy composite skin to the wing. Inspection of the spar through the wing skin is required to avoid wing disassembly. The thickness of the skin varies between 9 and 21 mm (0.36-0.83 in) and fasteners may be either titanium or ferrous. Pulsed eddy currents (PECs), generated by a probe centered over the fastener, demonstrate the capability of detecting simulated cracks within spars with the wing skin present. Comparison of signals from separate pick-up coils, mounted to either side of the excitation coil, is used to detect differences in induced eddy current fields, which arise in the presence of cracks. To overcome variability in PEC signal response due to variation in: 1) skin thickness; 2) fastener material and size; and 3) centering over fasteners, a large calibration data set is acquired. Multidimensional scores from a modified principal components analysis (PCA) of the data are reduced to 1-D using a discriminant analysis method. Under inspection conditions, calibration PCA scores combined with discriminant analysis permit rapid real time go/no-go PEC detection of cracks in F/A-18 inner wing spar.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.000 | 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".