Blar i Brage IMR på tidsskrift "The Journal of the Acoustical Society of America"
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Calibrating parametric sonars for backscattering applications
(Others, 2006) -
Calibrating split beam transducers at depth
(Journal article; Peer reviewed, 2006) -
Calibration sphere for low-frequency parametric sonars
(Journal article; Peer reviewed, 2007)The problem of calibrating parametric sonar systems at low difference frequencies used in backscattering applications is addressed. A particular parametric sonar is considered: the Simrad TOPAS PS18 Parametric Sub-bottom ... -
Calibration trials with multibeam sonars
(Others, 2003) -
Coincidence echo statistics
(Journal article; Peer reviewed, 1996)Two scatterers at similar range give an echo which may appear to be due to a single scatterer. Methods for determining target strength that depend on resolving single scatterers may fail in this instance. Statistics ... -
Comment on ''Some frequencies of underwater noise produced by fishing boats affecting albacore catch'' [J. Acoust. Soc. Am. 66, 296–299 (1979)]
(Others, 1980)An alternative explanation for the observations analyzed by Erickson is offered. Differences in catch-related success of boats participating in the West Coast Albacore fishery are attributed to the low-frequency content ... -
Comments on "A generalized target strength model for euphausiids, with applications to other zooplankton" [J. Acoust. Soc. Am. 95, 2452–2466 (1994)]
(Journal article; Peer reviewed, 1995)A major premise upon which this paper by Macaulay was written is flawed as is the formulation (both conceptually and mathematically) of the scattering models. The formulation is actually an assemblage and adaptation of ... -
Comparing Kirchhoff-approximation and boundary-element models for computing gadoid target strengths
(Journal article; Peer reviewed, 2002)To establish the validity of the boundary-element method (BEM) for modeling scattering by swimbladder-bearing fish, the BEM is exercised in several ways. In a computation of backscattering by a 50-mm-diam spherical void ... -
Comparison of copper and tungsten carbide calibration spheres
(Journal article; Peer reviewed, 1984)The properties of calibration spheres made from electrical-grade copper, denoted Cu, and tungsten carbide with 6% cobalt binder, denoted WC, are examined theoretically. Effects of variations in material, medium, and equipment ... -
Comparison of walleye pollock target strength estimates determined from in situ measurements and calculations based on swimbladder form
(Journal article; Peer reviewed, 1988)The target strength of walleye pollock (Theragra chalcogramma) at 38 kHz has been determined in each of two ways: (1) in situ measurement with dual-beam and split-beam echo sounders, and (2) theoretical calculation based ... -
Correcting acoustic measurements of scatterer density for extinction
(Journal article; Peer reviewed, 1990)Extinction is sometimes a major problem in acoustic surveys of fish stocks, as it often occurs when the fish are concentrated and easiest to survey. The same may be true of certain macrozooplankton, such as krill in swarms. ... -
Depth-dependent target strengths of gadoids by the boundary-element method
(Journal article; Peer reviewed, 2003)The depth dependence of fish target strength has mostly eluded experimental investigation because of the need to distinguish it from depth-dependent behavioral effects, which may change the orientation distribution. The ... -
Detecting Atlantic herring by parametric sonar
(Journal article; Peer reviewed, 2010-03-17)The difference-frequency band of the Kongsberg TOPAS PS18 parametric sub-bottom profiling sonar, nominally 1–6 kHz, is being used to observe Atlantic herring. Representative TOPAS echograms of herring layers and schools ... -
Determining the extinction cross section of aggregating fish
(Journal article; Peer reviewed, 1992)When fish are aggregated over a flat bottom, and fish and bottom echoes can be distinguished, it is possible to determine the fish extinction cross section by a simple application of the echo integration method. The theory ...