David T. I. Francis

TL;DR: Analytical and numerical scattering models with accompanying digital representations are used increasingly to predict acoustic backscatter by fish and zooplankton in research and ecosystem monitoring applications and, in certain cases, outperformed the numerical models under conditions where the numerical model did not converge.

TL;DR: In computations of target strength as a function of tilt angle for each of 15 surface-adapted gadoids for which the swimbladders were earlier mapped, BEM results are in close agreement with Kirchhoff-approximation-model results at each of the same four frequencies.

TL;DR: In this article, a method of overcoming the problem of nonuniqueness in the discretized Helmholtz integral equation is described, based on a partial application of the gradient formulation of Burton and Miller.

TL;DR: The problem of calibrating parametric sonar systems at low difference frequencies used in backscattering applications is addressed and results are applicable to the standard-target calibration of conventional sonars operating at low-kilohertz frequencies.

TL;DR: Based on detailed morphometric data on 15 gadoid swimbladders, the boundary-element method has been exercised to determine how the orientation dependence of target strength changes with pressure under the assumption that the fish swimbladder remains constant in shape and volume.