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DWBA

Source: vignettes/dwba/index.Rmd
index.Rmd

Overview

Benchmarked Validated
Theory Implementation

These pages follow the weak-scattering elongated-body formulation and later applied fisheries-acoustics usage of the distorted-wave Born approximation (Morse and Ingard 1968; Chu, Foote, and Stanton 1993; Stanton, Chu, and Wiebe 1998).

The distorted wave Born approximation (DWBA) is the package’s main weak-scattering fluid-body model for elongated targets that are no longer well represented by a single canonical sphere, cylinder, or spheroid.

Core idea

Treat the target as a weak perturbation of the surrounding fluid, retain the two-way phase accumulation along the body, and integrate the local cross-sectional response over a segmented centerline.

Best for

  • Weakly scattering fluid-like elongated bodies
  • Zooplankton-like or swimbladder-less flesh-body calculations where density and sound-speed contrasts remain modest
  • Arbitrary profiles that do not fit a single canonical exact geometry

Supports

  • FLS objects with canonical or arbitrary shapes
  • Material contrasts expressed naturally as g_{21} and h_{21} relative to seawater
  • Segmented body-axis integrations in the monostatic backscatter setting

Main assumptions

  • Small density and sound-speed contrasts
  • First-order Born linearization
  • Single scattering with no strong internal reverberation
  • Fluid-like, non-elastic interior response

Validation status

  • Benchmarked against the canonical weakly scattering targets summarized by Jech et al. (2015).
  • Validated against the published McGehee MATLAB workflow and an independent DWBA implementation.

Family pages

  • Implementation: object workflows, spectra, and validation tables
  • Theory: Born linearization, contrast term, and centerline integral

References

Chu, Dezhang, Kenneth G. Foote, and Timothy K. Stanton. 1993. “Further Analysis of Target Strength Measurements of Antarctic Krill at 38 and 120 kHz: Comparison with Deformed Cylinder Model and Inference of Orientation Distribution.” The Journal of the Acoustical Society of America 93 (5): 2985–88. https://doi.org/10.1121/1.405818.
Morse, Philip M., and K. Uno Ingard. 1968. Theoretical Acoustics. New York, NY: McGraw-Hill.
Stanton, Timothy K., Dezhang Chu, and Peter H. Wiebe. 1998. “Sound Scattering by Several Zooplankton Groups. II. Scattering Models.” The Journal of the Acoustical Society of America 103 (1): 236–53. https://doi.org/10.1121/1.421110.