Low- To Mid-Frequency Scattering From Elastic Objects on a Sand Sea Floor: Simulation of Frequency and Aspect Dependent Structural Echoes

Zampolli, Mario; Espana, Aubrey L.; Williams, Kevin L.; Kargl, Steven G.; Thorsos, Eric I.; Lopes, Joseph L.; Kennedy, Jermaine L.; Marston, Philip L.

doi:10.1142/s0218396x12400073

Cited by 23 publications

(9 citation statements)

References 6 publications

(9 reference statements)

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“…The model takes advantage of the cylindrical symmetry of the problem through an angular decomposition of the full 3-D problem into a series of independent, 2-D Fourier modal subproblems. 3 The decomposition is in terms of the angle around the azimuth, or equivalently the circumference, of the shell. In order to avoid confusion with the azimuthal angle / defined for the global experimental geometry discussed in Secs.…”

Section: A Model Formulationmentioning

confidence: 99%

Acoustic scattering from a water-filled cylindrical shell: Measurements, modeling, and interpretation

Espana

Williams

Plotnick

et al. 2014

The Journal of the Acoustical Society of America

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Understanding the physics governing the interaction of sound with targets in an underwater environment is essential to improving existing target detection and classification algorithms. To illustrate techniques for identifying the key physics, an examination is made of the acoustic scattering from a water-filled cylindrical shell. Experiments were conducted that measured the acoustic scattering from a water-filled cylindrical shell in the free field, as well as proud on a sand-water interface. Two modeling techniques are employed to examine these acoustic scattering measurements. The first is a hybrid 2-D/3-D finite element (FE) model, whereby the scattering in close proximity to the target is handled via a 2-D axisymmetric FE model, and the subsequent 3-D propagation to the far field is determined via a Helmholtz integral. This model is characterized by the decomposition of the fluid pressure and its derivative in a series of azimuthal Fourier modes. The second is an analytical solution for an infinitely long cylindrical shell, coupled with a simple approximation that converts the results to an analogous finite length form function. Examining these model results on a mode-by-mode basis offers easy visualization of the mode dynamics and helps distinguish the different physics driving the target response.

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Section: A Model Formulationmentioning

confidence: 99%

Acoustic scattering from a water-filled cylindrical shell: Measurements, modeling, and interpretation

Espana

Williams

Plotnick

et al. 2014

The Journal of the Acoustical Society of America

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“…In (2), we use a free-field scattering amplitude derived from a hybrid 2D/3D model. The hybrid 2D/3D model implemented a 2D finite-element model (FEM) prediction of the target response on a surface near the target, and then propagates the target response to some specified range using a discrete form of the 3D Helmholtz integral with a freefield Green function [7][8][9]. The hybrid 2D/3D model can be applied to targets with a cylindrical symmetry.…”

Section: Application Of the Model To Circular Sasmentioning

confidence: 99%

Generation of Synthetic SAS Data for Targets Near the Seafloor: Propagation Component

Kargl¹

2013

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Award Number: N00014-10-1-0114 http://www.apl.washington.edu/projects/projects.php/ Overview:This report contains three parts. First, a list of archival journal publications, conference proceedings, and abstracts for oral presentations are listed. It is noted that the research reported in these papers and presentations was performed in conjunction with "Generation of Synthetic SAS Data for Targets near the Seafloor: Propagation Component," (ONR Award N00014-07-G-0557/0023). Second, the fast ray model for target scattering in a homogeneous waveguide has yet to be published in an archival journal, but an overview has been given in the conference proceedings for the First International Conference and Exhibition on Underwater Acoustics, Corfu, Greece. As this proceedings paper is currently only available from the conference website and its availability may not be ensured, the paper is included in this final report. Finally, recent benchmark model comparisons of the fast ray model and a wave propagation model, based on the trapped modes in propagation in a homogeneous Pekeris waveguide, revealed an significant deficiency in the implementation of fast ray model. The details of the deficiency and the correction to the implementation of the fast ray model are given in a section that follows the proceedings paper.

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“…Detecting an object on a seafloor composed of sand and mud in the shallow water is a significant technology in the military detection field [1][2][3]. In this problem, the reflections coming from the clutter surrounding a target and the ambient noise are the main hurdles.…”

Section: Introductionmentioning

confidence: 99%

“…In this situation, the approach employed by the Applied Physics Lab. (APL) at the University of Washington, Seattle, WA, USA draws attention for detecting sea mines at the bottom of the seabed in the shallow sea [1,2]. This approach is based on the mathematical target and seabed models to obtain the features of the bottoming target, which are simultaneously verified with the measurements.…”

Section: Introductionmentioning

confidence: 99%

Underwater Cylindrical Object Detection Using the Spectral Features of Active Sonar Signals with Logistic Regression Models

Seo

et al. 2018

Applied Sciences

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Abstract:The issue of detecting objects bottoming on the sea floor is significant in various fields including civilian and military areas. The objective of this study is to investigate the logistic regression model to discriminate the target from the clutter and to verify the possibility of applying the model trained by the simulated data generated by the mathematical model to the real experimental data because it is not easy to obtain sufficient data in the underwater field. In the first stage of this study, when the clutter signal energy is so strong that the detection of a target is difficult, the logistic regression model is employed to distinguish the strong clutter signal and the target signal. Previous studies have found that if the clutter energy is larger, false detection occurs even for the various existing detection schemes. For this reason, the discrete Fourier transform (DFT) magnitude spectrum of acoustic signals received by active sonar is applied to train the model to distinguish whether the received signal contains a target signal or not. The goodness of fit of the model is verified in terms of receiver operation characteristic (ROC), area under ROC curve (AUC), and classification table. The detection performance of the proposed model is evaluated in terms of detection rate according to target to clutter ratio (TCR). Furthermore, the real experimental data are employed to test the proposed approach. When using the experimental data to test the model, the logistic regression model is trained by the simulated data that are generated based on the mathematical model for the backscattering of the cylindrical object. The mathematical model is developed according to the size of the cylinder used in the experiment. Since the information on the experimental environment including the sound speed, the sediment type and such is not available, once simulated data are generated under various conditions, valid simulated data are selected using 70% of the experiment cylinder data. The selected simulated data are used to train the model. Randomly selected experiment cylinder data, which are 70% of the total experimental cylinder data, and the rock measurement data are used to test the model. This process is repeatedly carried out 1000 times. The results show that the proposed method is effective under the circumstance where experimental data are not sufficient and a mathematical model is available for a target.

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Low- To Mid-Frequency Scattering From Elastic Objects on a Sand Sea Floor: Simulation of Frequency and Aspect Dependent Structural Echoes

Cited by 23 publications

References 6 publications

Acoustic scattering from a water-filled cylindrical shell: Measurements, modeling, and interpretation

Acoustic scattering from a water-filled cylindrical shell: Measurements, modeling, and interpretation

Generation of Synthetic SAS Data for Targets Near the Seafloor: Propagation Component

Underwater Cylindrical Object Detection Using the Spectral Features of Active Sonar Signals with Logistic Regression Models

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