Extracting elastic target information from acoustic scattering data of underwater munitions

2016 ◽  
Vol 140 (4) ◽  
pp. 3450-3450
Author(s):  
David E. Malphurs
Keyword(s):  
Acoustic Scattering ◽  
Scattering Data ◽  
Target Information

scholarly journals Inference of biological and physical parameters in an internal wave using multiple-frequency, acoustic-scattering data

2003 ◽  
Vol 60 (5) ◽  
pp. 1033-1046 ◽  
Author(s):  
Joseph D. Warren ◽  
Timothy K. Stanton ◽  
Peter H. Wiebe ◽  
Harvey E. Seim
Keyword(s):  
Internal Wave ◽  
Field Experiments ◽  
Gulf Of Maine ◽  
Acoustic Scattering ◽  
Primary Source ◽  
Theoretical Work ◽  
Scattering Data ◽  
Physical Parameters ◽  
Multiple Frequency ◽  
Scattering Spectra

Abstract High-frequency sound (>10 kHz) is scattered in the ocean by many different processes. In the water column, marine organisms are often assumed to be the primary source of acoustic backscatter. Recent field experiments and theoretical work suggest that the temperature and salinity microstructure in some oceanic regions could cause acoustic scattering at levels comparable to that caused by marine life. Theoretical acoustic-scattering models predict that the scattering spectra for microstructure and organisms are distinguishable from each other over certain frequency ranges. A method that uses multiple-frequency acoustic data to exploit these differences has been developed, making it possible to discriminate between biological and physical sources of scattering under some conditions. This method has been applied to data collected in an internal wave in the Gulf of Maine. For regions of the internal wave in which the dominant source of scattering is either biological or physical in origin, it is possible to combine the acoustic-scattering data and temperature and salinity profiles with acoustic-scattering models to perform a least-squares inversion. Using this approach, it is possible to estimate the dissipation rate of turbulent kinetic energy for some regions of the internal wave, and the length and numerical abundance of the dominant biological scatterer, euphausiids, in others.

A Novel Classification Method of Fish Based on Multi-Feature Fusion

2015 ◽  
Vol 713-715 ◽  
pp. 1513-1519 ◽  
Author(s):  
Wei Dong Du ◽  
Bao Wei Chen ◽  
Hai Sen Li ◽  
Chao Xu
Keyword(s):  
Discrete Cosine Transform ◽  
Feature Fusion ◽  
Acoustic Scattering ◽  
Scattering Data ◽  
Support Vector ◽  
Svm Classifier ◽  
Correct Identification ◽  
Classification Problems ◽  
Cosine Transform ◽  
Identification Rate

In order to solve fish classification problems based on acoustic scattering data, temporal centroid (TC) features and discrete cosine transform (DCT) coefficients features used to analyze acoustic scattering characteristics of fish from different aspects are extracted. The extracted features of fish are reduced in dimension and fused, and support vector machine (SVM) classifier is used to classify and identify the fishes. Three kinds of different fishes are selected as research objects in this paper, the correct identification rates are given based on temporal centroid features and discrete cosine transform coefficients features and fused features. The processing results of actual experimental data show that multi-feature fusion method can improve the identification rate at about 5% effectively.

Characterization of a cylindrical rod by inversion of acoustic scattering data

Ultrasonics ◽  
2014 ◽  
Vol 54 (6) ◽  
pp. 1559-1567 ◽  
Author(s):  
Mohammadreza Kari ◽  
Farhang Honarvar
Keyword(s):  
Acoustic Scattering ◽  
Scattering Data

Seabed target discrimination using multistatic acoustic scattering data

2016 ◽  
Vol 140 (4) ◽  
pp. 3170-3170
Author(s):  
Erin M. Fischell ◽  
Henrik Schmidt
Keyword(s):  
Acoustic Scattering ◽  
Scattering Data ◽  
Target Discrimination

Size Determination of Immersed and Embedded Cylindrical Rods by Inversion of Acoustic Scattering Data

2015 ◽  
Vol 798 ◽  
pp. 314-318
Author(s):  
Kari Mohammadreza ◽  
Masoumeh Sadraei
Keyword(s):  
Short Pulse ◽  
Acoustic Scattering ◽  
Scattering Data ◽  
Size Determination ◽  
Good Convergence ◽  
Inversion Technique ◽  
Expansion Technique ◽  
Resonance Frequencies ◽  
Scattered Fields

In this paper, a new approach is proposed for nondestructive size determination of immersed and embedded cylindrical rods by inversion of acoustic scattering data. The normal mode expansion technique is used for modelling the scattered field. Also, the experimental backscattered field is measured using short pulse MIIR technique. The Genetic algorithm is the inversion technique used for measuring the diameters of the rods. The inversion technique matches the modelled and experimental scattered fields at resonance points, so the diameters of the rods can be estimated. The numerical results indicate that proper selection of resonance frequencies leads to accurate measurement of diameter. The proposed approach showed very good convergence and the results obtained were found to agree very well with available data.

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.

THE USE OF THE HERGLOTZ FUNCTION METHOD TO RECONSTRUCT OBSTACLES FROM REAL AND FROM SYNTHETIC SCATTERING DATA

2001 ◽  
Vol 09 (02) ◽  
pp. 655-670 ◽  
Author(s):  
PIERLUIGI MAPONI ◽  
FRANCESCO ZIRILLI
Keyword(s):  
Electromagnetic Scattering ◽  
Acoustic Waves ◽  
Function Method ◽  
Scattering Problem ◽  
Acoustic Scattering ◽  
Inverse Scattering Problem ◽  
Scattering Data ◽  
Scattering Problems ◽  
Herglotz Function ◽  
Incident Waves

We consider the problem of the reconstruction of the shape of an obstacle from some knowledge of the scattered waves generated from the interaction of the obstacle with known incident waves. More precisely we study this inverse scattering problem considering acoustic waves or electromagnetic waves. In both cases the waves are assumed harmonic in time. The obstacle is assumed cylindrically symmetric and some special incident waves are considered. This allows us to formulate the two scattering problems, i.e. the acoustic scattering problem and the electromagnetic scattering problem, as a boundary value problem for the scalar Helmholtz equation in two independent variables. The numerical algorithms proposed are based on the Herglotz Function Method, which has been introduced by Colton and Monk.1 We report the results obtained with these algorithms in the reconstruction of simple obstacles with Lipschitz boundary using experimental electromagnetic scattering data, that is the Ipswich Data2,3 and in the reconstruction of "multiscale obstacles" using synthetic acoustic scattering data.

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