Measuring the acoustic scattering response of small groups of live fish in a laboratory tank

2015 ◽  
Vol 137 (4) ◽  
pp. 2362-2362
Author(s):  
Maria P. Raveau ◽  
Christopher Feuillade ◽  
Gabriel Venegas ◽  
Preston S. Wilson
Keyword(s):  
Small Groups ◽  
Acoustic Scattering ◽  
Live Fish ◽  
Scattering Response ◽  
Laboratory Tank

scholarly journals Measuring the acoustic scattering response of small groups of live fish in a laboratory tank

2015 ◽  
Author(s):  
Maria P. Raveau ◽  
Christopher Feuillade ◽  
Gabriel Venegas ◽  
Preston Scott Wilson
Keyword(s):  
Small Groups ◽  
Acoustic Scattering ◽  
Live Fish ◽  
Scattering Response ◽  
Laboratory Tank

Predictions of the acoustic scattering response of free‐methane bubbles in muddy sediments

1996 ◽  
Vol 99 (1) ◽  
pp. 163-172 ◽  
Author(s):  
Anthony P. Lyons ◽  
Michael E. Duncan ◽  
Aubrey L. Anderson ◽  
James A. Hawkins
Keyword(s):  
Acoustic Scattering ◽  
Scattering Response ◽  
Muddy Sediments

scholarly journals Measurements of acoustic-scattering spectra from the whole and parts of Atlantic mackerel

2009 ◽  
Vol 66 (6) ◽  
pp. 1169-1175 ◽  
Author(s):  
Tonje Lexau Nesse ◽  
Halvor Hobæk ◽  
Rolf J. Korneliussen
Keyword(s):  
Frequency Response ◽  
Acoustic Scattering ◽  
Ex Situ ◽  
Target Strength ◽  
Model Parameters ◽  
Acoustic Frequency ◽  
Atlantic Mackerel ◽  
Scattering Spectra ◽  
Laboratory Tank

Abstract Nesse, T. L., Hobæk, H., and Korneliussen, R. J. 2009. Measurements of acoustic-scattering spectra from the whole and parts of Atlantic mackerel. – ICES Journal of Marine Science, 66: 1169–1175. Atlantic mackerel (Scomber scombrus) are weak sound scatterers compared with fish that have swimbladders. Accurate acoustic estimates of mackerel abundance require estimates of target strength. Different parts of mackerel may dominate the backscattering spectra. Mackerel schools are acoustically recognized mainly by backscatter four times stronger at 200 kHz than at 38 kHz. Simulations have established that backscatter from only the flesh and the backbone could explain this frequency response, although there are uncertainties in the model parameters and simplifications. In this paper, experiments conducted in a laboratory tank to investigate the complexity of mackerel backscatter are discussed. Acoustic backscatter was measured over the frequency range 65–470 kHz from individual dead mackerel, and their backbones, heads, and skulls. Backscatter from the backbones was measured at several angles of incidence. Grating lobes (Bragg scattering) appeared at different angles, depending on the acoustic frequency and the spacing of the vertebrae. These lobes were evident in backbone backscatter after propagating through the flesh and can be used, in principle, to determine mackerel size acoustically. The frequency response of individual, ex situ Atlantic mackerel estimated from these measurements did not match that from the measurements of in situ mackerel schools. Further investigation is warranted.

The echo of a fault or fracture

Geophysics ◽  
2000 ◽  
Vol 65 (1) ◽  
pp. 176-189 ◽  
Author(s):  
Geir U. Haugen ◽  
Michael A. Schoenberg
Keyword(s):  
Acoustic Scattering ◽  
Seismic Energy ◽  
Scattering Data ◽  
Isotropic Case ◽  
Fracture Characterization ◽  
Isotropic Media ◽  
Single Well ◽  
Analytical Formulae ◽  
Scattering Response ◽  
Physical Features

The seismic response of single faults, joints, or fractures of large planar extent is analyzed. These are modeled as nonwelded interfaces. In spite of the large range of scale, all are assumed to behave according to linear slip theory. Such a model has been considered theoretically and experimentally before. The aim of this paper is to give a physical interpretation to such a linear slip interface; to provide simple analytical formulae for the scattering response, even when the fracture is embedded in an anisotropic background medium; and to relate the properties of this scattering response, in the isotropic case, to the physical features of the fracture. The analysis shows that the reflectivity and transmissivity of the fracture depend on slowness along the fracture and on frequency. The frequency dependence arises from the fact that, even though the fracture is assumed to be an interface of zero thickness, it still has at least two characteristic widths that provide the length scales necessary for scattering dependence on wavelength. For isotropic media, the PP and SS reflections generally decrease in amplitude with increasing slowness along the fracture. At certain slowness values, they reach minima before starting to increase for still larger slownesses. The slowness value of these minima reveals the fracture compliances, from which inferences about the physical properties of the fracture may be drawn. Both forward modeling of the acoustic response of a fracture and the estimation of fracture properties from acoustic scattering data can benefit from the type of analysis presented here. The range of such problems extends from the scattering of earthquake‐generated seismic energy by major faults in the earth, through reservoir fracture characterization from single‐well sonic imaging, to the characterization of flaws or poorly bonded surfaces in ultrasonic nondestructive testing.

scholarly journals The Autoregressive Moving Average with Exogenous Excitation Model for Acoustic Scattering from Underwater Objects

2020 ◽  
Vol 18 (02) ◽  
pp. 157-162
Author(s):  
Lubna Farhi ◽  
Farhan Ur Rehman ◽  
Agha Yasir Ali
Keyword(s):  
Time Domain ◽  
Moving Average ◽  
Acoustic Scattering ◽  
Autoregressive Moving Average ◽  
Mean Square ◽  
Exogenous Variables ◽  
Scattering Response ◽  
Mean Square Error Criterion ◽  
Excitation Model ◽  
Initial Results

This study aims to identify and predict objects underwater using the autoregressive moving average with exogenous excitation (ARMX) model in such a way that the outcome of the model is similar to actual measurements. It is used for parameter estimation. This model is validated by comparing results in actual model with ARMX model, autoregressive with an exogenous variables, and Box Jenkins (BJ) model. The results are analyzed in frequency and time domain by using mean square error criterion. Initial results show that ARMX predicts the acoustic scattering response with an accuracy of 96%, while ARX provides an accuracy of 78%, and BJ model poorly estimates the signal with an accuracy of 35%. ARMX also provides higher accuracy of detection by 7-8% as compared to the existing techniques.

Small Groups From a Communication Perspective

1998 ◽  
Vol 43 (2) ◽  
pp. 107-108
Author(s):  
Judith A. Kolb ◽  
Jennifer Jones Corley
Keyword(s):  
Small Groups

Pint-Sized Democracy? Small Groups and Civic Life

PsycCRITIQUES ◽  
2013 ◽  
Vol 58 (8) ◽  
Author(s):  
Etienne Pelaprat
Keyword(s):  
Small Groups ◽  
Civic Life
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