After this chapter, you should be able to
- Check sampling, synchronisation and missing intervals.
- Build a seasonal or persistence baseline.
- Calculate and interpret a standardised anomaly score.
- Separate drift, environment and possible damage hypotheses.
- Design monitoring escalation and fallback.
Engineering context and methodSource §Lesson 06 · Engineering context and method · GOV-02 · GOV-03 · RES-01 · RES-07 · DATA-03
Sensor observations combine structural response with temperature, traffic, moisture, calibration, synchronisation and data-loss effects. Freeze acquisition metadata and quality flags before modelling. Split by time, retain later periods for testing, and compare with persistence or seasonal baselines. An alert is a triage signal; diagnosis needs engineering context, corroborating sensors and inspection evidence.
Verified worked exampleSource §Lesson 06 · Verified worked example · GOV-02 · GOV-03 · RES-01 · RES-07 · DATA-03
Standardised monitoring excursion
A reference window has mean 120 microstrain and standard deviation 4 microstrain; a new value is 134 microstrain.
- Difference
134 − 120
14 microstrain - Standardise
14 / 4
z = 3.5 - Interpret
compare quality, temperature and neighbouring sensors
review trigger
Result. z = 3.5 relative to the declared window. This is not a probability of damage or a diagnosis.
Practical lab · 5 h lesson effortSource §Lesson 06 · Practical lab · 5 h lesson effort · GOV-02 · GOV-03 · RES-01 · RES-07 · DATA-03
- Use a synthetic, checksum-frozen multichannel signal with temperature and missing intervals.
- Implement quality gates, a persistence baseline and a rolling robust anomaly score.
- Test on a later time block and inspect at least five alerts.
- Write an alert packet with context, confidence, abstention, escalation and sensor-failure fallback.
Failure modes to investigateSource §Lesson 06 · Failure modes to investigate · GOV-02 · GOV-03 · RES-01 · RES-07 · DATA-03
- Random time split.
- Clock drift or missing intervals ignored.
- Temperature effects described as damage.
- Threshold selected after viewing the final events.
- No fallback when sensors or communications fail.
Knowledge checksSource §Lesson 06 · Knowledge checks · GOV-02 · GOV-03 · RES-01 · RES-07 · DATA-03
| Question | Answer rationale |
|---|---|
| What does z = 3.5 mean? | The value is 3.5 reference-window standard deviations above that window mean. |
| Does it diagnose damage? | No; alternative environmental, operational and data-quality causes remain. |
| Why use a later test period? | It better represents forecasting or future monitoring use. |
| Why use neighbouring sensors? | Corroboration helps distinguish local sensor issues from system response. |
| Who determines an asset action? | The authorised engineering process, not the anomaly score. |
Key points
- Start from the accountable engineering decision and its consequence.
- Compare against a transparent non-AI baseline.
- Validate on a split that represents intended use and retain human authority.
Source references recorded by the supplied chapter
- ASCE Policy Statement 573 and Code of Ethics.
- Peer-reviewed structural-health-monitoring and computer-vision reviews listed as RES-07.
- NIST AI RMF 1.0.