{
  "abstract": "Acoustic \"ping\" testing of bullion is empirical: it compares a coin's ringing frequency with frequencies recorded for the same coin type, so it cannot assess a specimen absent from the reference library. This work replaces the comparison with an absolute measurement, computed from the measured resonance and geometry through a physical model rather than retrieved from a library. Free-plate flexural resonance is calibrated on five machined aluminium discs ($a/t=2.58$--$10.75$), recovering an empirical finite-thickness coefficient $β=0.895\\pm0.047$ that reduces the worst-case departure from thin-plate theory from 8.9% to 0.75%. A fill factor, the ratio of a coin's displaced volume to its nominal cylinder, supplies the effective thickness that relief hides from calipers, extending the calibration to struck coins. The readout is the plate wave speed $c_{p}=\\sqrt{E/ρ(1-ν^{2})}$, a material constant, conditioned on an assumed Poisson's ratio. On six struck 0.999 copper rounds not used in the calibration it recovers a Young's modulus of $119.1\\pm6.7$ GPa, inside the accepted 110 to 128 GPa. The recovered wave speeds form distinct observed groups across the measured specimens, with the strongest independent validation provided by these copper rounds. The $(3,0)/(2,0)$ mode ratio falls below its thin-plate value in thirteen of sixteen specimens (one-sided sign test, $p=0.011$), as finite-thickness theory predicts. Weighing displaced mass to 0.1 mg rather than 0.1 g cut per-specimen volume uncertainty from 1.6% to 30% to 0.5% to 2.6% and shrank an apparent 11% design-dependent bias to a 4.7% residual on one deeply relieved silver design. The readout is now limited by tabulated elastic constants and the assumed Poisson's ratio, not by the acoustics, which are reproducible to 0.15%.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.29194",
  "author_total": 2,
  "authors": [
    {
      "name": "Sylvia Dong"
    },
    {
      "name": "Takyiu Liu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6h27crzy8qxbg.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.29194",
  "fulltext_url": null,
  "id": "6h27crzy8qxbg",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.29194",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "eess.AS"
    ],
    [
      "arxiv",
      "physics.class-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.29194",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6h27crzy8qxbg.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:19Z",
      "native_id": "2610.29194",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.29194"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.class-ph",
      "subfield": "general"
    }
  ],
  "title": "An Absolute Acoustic Readout of Plate Wave Speed for Bullion Authentication, Using a Measured Fill-Factor Correction for Struck Coins",
  "title_text": "An Absolute Acoustic Readout of Plate Wave Speed for Bullion Authentication, Using a Measured Fill-Factor Correction for Struck Coins",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:19Z",
  "url": "https://research.draconitic.com/paper/6h27crzy8qxbg",
  "venue": "arXiv",
  "versions": []
}