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SOEMS

Source: vignettes/calibration/index.Rmd
index.Rmd

Overview

Benchmarked Validated
Theory Implementation

These pages are grounded in the standard-target calibration literature for elastic reference spheres (Dragonette, Numrich, and Frank 1981; Foote 1990; MacLennan 1981).

SOEMS is the package’s elastic solid-sphere family for standard-target calibration work. It follows the classic solid elastic sphere literature and is intended for metal calibration spheres whose compressional and shear wave physics matter directly.

Core idea

Expand the exterior acoustic field and the interior elastic displacement field in spherical modes, enforce pressure, normal-velocity, and traction conditions at the sphere surface, and reconstruct the far-field backscatter from the resulting phase-shifted partial waves.

Best for

  • Calibration spheres made of tungsten carbide, copper, aluminum, steel, or similar elastic solids
  • Frequency-response calculations for standard-target calibration workflows
  • Benchmarking elastic spherical scattering against literature values

Supports

  • CAL objects representing homogeneous elastic spheres
  • Solid elastic interiors with both longitudinal and shear wave support
  • Medium 1 as seawater and medium 2 as the elastic solid sphere

Main assumptions

  • Perfectly spherical homogeneous solid target
  • Linear elasticity in the solid interior
  • Inviscid exterior fluid
  • No shell or internal cavity

Validation status

  • Benchmarked against published calibration-sphere targets used throughout the package documentation.
  • Validated against echoSMs, sphereTS, and the NOAA calibration applet.

Family pages

  • Implementation: calibration workflows and benchmark comparisons
  • Theory: elastic-sphere modal theory and phase-shift representation

References

Dragonette, Louis R., S. K. Numrich, and Laurence J. Frank. 1981. “Calibration Technique for Acoustic Scattering Measurements.” The Journal of the Acoustical Society of America 69 (4): 1186–89. https://doi.org/10.1121/1.385699.
Foote, K. G. 1990. “Spheres for Calibrating an Eleven-Frequency Acoustic Measurement System.” ICES Journal of Marine Science 46 (3): 284–86. https://doi.org/10.1093/icesjms/46.3.284.
MacLennan, D. N. 1981. “The Theory of Solid Spheres as Sonar Calibration Targets.” Scottish Fisheries Research Report 22. Department of Agriculture; Fisheries for Scotland.