Multi-output subspace identification of complex Bloch wavenumbers in 1D periodic structures
Bibliographic record
Abstract
The experimental characterization of complex dispersion curves is challenging in phononic crystals, composites, periodic, architected or metamaterials. Recent studies have highlighted the importance of subspace identification methods in determining wave propagation properties through complex wavenumbers and, consequently, in characterizing a complex structure experimentally. Still, such methods have not yet been adapted for 1D periodic structures with periodic sampling limitations. This work introduces a Subspace-based complex Bloch WAveNumber identification method (SWAN) which can take advantage of full-field vibration measurements (i.e., multiple data points per unit cell) to statistically reduce the negative impact of having a limited number of unit cells. The SWAN method is based on a state-space representation of the wave finite element method. A symplectic state-space model is formulated and mathematically proved to represent the original system. Eventually, the proposed method enhances complex wavenumber estimates when a small number of unit cells is available. In addition, a general-purpose, adaptive spectral mask is introduced to reject physically irrelevant identification results, enabling straightforward denoising of the identified dispersion curves. The proposed approach is validated through numerical and experimental applications. • Subspace-based identification of complex wavenumbers in 1D periodic structures. • Multi-modal & multi-output wavenumber identification. • State-space model proposed for symplectic subspace identification. • Enhanced bandgap characterization with full-field vibration measurements. • General-purpose spectral mask for wavenumber selection.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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".