Adaptive Subband Decomposition with Envelope Spectrum Consistency Voting for Cross-Domain Bearing Fault Feature Certification

Abstract Subband decomposition (SBD) provides a computationally efficient framework for bearing fault diagnosis, but existing implementations assume uniform spectral partitioning that does not account for dataset-specific resonance distributions. This work proposes an adaptive SBD variant in which filter bank edges are determined by a consistency voting procedure over envelope spectrum peaks, selecting the K frequency bands that appear most persistently across signal windows. The method couples adaptive decomposition with a feature certification protocol based on mutual information and Jensen-Shannon divergence bootstrap confidence intervals. Certification is evaluated across six transfer pairs spanning three heterogeneous bearing datasets — MFPT, Paderborn, and Fraunhofer LBF — with distinct fault mechanisms, sensor configurations, and operating conditions. Adaptive SBD with K=8 subbands and RMS inter-domain normalisation yields three certified-invariant features (kurtosis, shape factor, and clearance factor) against one for uniform SBD, with a 49% reduction in mean bootstrap confidence interval width. Analysis of per-pair certification scores reveals a structural asymmetry between distributional stability and discriminative transferability: the pair MFPT→LBF suffers a catastrophic accuracy drop (0.875→0.077) attributable to filter bank boundary mismatch when the source dataset uses narrow adaptive subbands (≈162 Hz) and the target requires a uniform fallback (1600 Hz), a condition detectable from the band-edge log prior to deployment. The per-window voting mechanism defines a narrow stability basin around its default hyperparameters; small deviations cause reversion to uniform fallback, motivating explicit diagnostic validation for new datasets. Distributional certification is a necessary condition for safe cross-domain deployment but is not sufficient to guarantee discriminative accuracy: a partition compatibility gate, formalised as Stage 0 of the certification pipeline, automatically detects the structural failure mode in which nominally identical subbands cover incompatible frequency ranges.