1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Orientation dependence of broadband acoustic backscattering from live squid
Rent:
Rent this article for
USD
10.1121/1.3701876
/content/asa/journal/jasa/131/6/10.1121/1.3701876
http://aip.metastore.ingenta.com/content/asa/journal/jasa/131/6/10.1121/1.3701876

Figures

Image of FIG. 1.
FIG. 1.

(a) The pulse-echo system and experimental setup. The shaded box represents the NI system containing the central labview control program. (b) Tethering system used in the experiment and the definition of angle of orientation relative to incident acoustic signal. Solid lines represent monofilament lines outside of the squid body. Dashed lines represent monofilament lines running through the mantle cavity.

Image of FIG. 2.
FIG. 2.

(a) Transmit signal measured at the output of the power amplifier. (b) Received calibration signal. (c) Spectrum of the received calibration signal. (d) Envelope of the autocorrelation function of the received calibration signal, normalized to the maximum value at 0 μs.

Image of FIG. 3.
FIG. 3.

TS prediction versus angle of orientation at four frequencies (60, 70, 85, and 100 kHz) for the three-dimensional DWBA numerical model using arms-folded squid shapes with and without the fins, and the analytical DWBA prolate spheroid model. The arrow indicates the scattering contribution from the fins.

Image of FIG. 4.
FIG. 4.

TS predictions versus frequency for the three-dimensional DWBA numerical model using arms-folded squid shape and the analytical DWBA prolate spheroid model at four angles of orientation (0°, 45°, 90°, 135° from normal incidence). The usable band (gray area) in the experiment lies entirely in the geometric scattering region.

Image of FIG. 5.
FIG. 5.

Compressed pulse output envelope of the three-dimensional DWBA numerical model using two fixed squid shapes through two full rotations (720°): (a) arms-folded configuration and (b) arms-splayed configuration. The CPO envelopes are normalized to the maximum envelope value in each of the plots. The strong sinusoidal pattern in both plots corresponds to the location of the squid arms during the rotation.

Image of FIG. 6.
FIG. 6.

Temporal characteristics of the scattering at normal incidence. (a) Model predictions given by the three-dimensional DWBA numerical model with arms-folded and arms-splayed squid shapes and the analytical DWBA prolate spheroid model. (b) Experimental data from 15 individual pings overlaid at normal incidence. All CPO envelopes (model prediction and data) were normalized to the maximum value in each model prediction or each ping.

Image of FIG. 7.
FIG. 7.

Compressed pulse output envelope of (a) the experimental data and (b) the three-dimensional DWBA numerical model using a hybrid squid shape with randomized arms over two full rotations (720°). The CPO envelopes are normalized to the maximum envelope value in each of the plots. Faint vertical lines in the experimental data are due to noise not effectively eliminated by the background reverberation subtraction.

Image of FIG. 8.
FIG. 8.

Data-model comparison of TS versus angle of orientation at four frequencies (60, 70, 85, and 100 kHz). Hybrid randomized squid shapes with three fin shapes were used in the three-dimensional DWBA numerical model: (A) original asymmetric fins, (B) artificial symmetric fins, (C) no fins. The experimental data are represented by dots. The gray area indicates the range of ±1 standard deviation from the mean of the model predictions. The arrow indicates the scattering contribution of the fins. The cut-off pattern near the bottom of each plot is resulted from omitting experimental data and model predictions lower than the noise threshold.

Image of FIG. 9.
FIG. 9.

Averaged TS versus frequency for the experimental data, the analytical DWBA prolate spheroid model, and the three-dimensional DWBA numerical model using both fixed and hybrid randomized squid shapes in two planes (data only available in the lateral plane). All averages were done in the linear domain over ±2 standard deviations (σ) from the mean angle (μ) and converted to TS. (a) Averages in the dorsal-ventral plane. (b) Averages in the lateral plane.

Image of FIG. 10.
FIG. 10.

Noise addition procedure for model predictions. (a) The frequency dependent background noise profile (including reverberation) across the usable band of the experiment. (b) TS predictions with noise added (top row) and without noise added (bottom row) based on the three-dimensional DWBA numerical model. The solid line is the mean of the measured or added noise. The gray or white area between the two dashed lines indicates the range between ±1 standard deviation from the mean. The brackets indicate regions where the effect of noise addition is more prominent. Model predictions below the noise threshold were omitted.

Image of FIG. 11.
FIG. 11.

Comparison of the performance of the three-dimensional DWBA numerical model and the analytical DWBA prolate spheroid model at two frequencies. Frequency-dependent noise was added to both models to enable valid comparison with the data. Dots represent the ping-by-ping experimental data. The gray area indicates the range of ±1 standard deviation from the mean of the models. Note that the experimental data and model predictions lower than the background noise threshold (black lines) were not omitted to illustrate the difference clearly.

Tables

Generic image for table
TABLE I.

Dimensions and ranges of angle of orientation for the squid used in the acoustic backscattering measurements. All dimensional measurements were conducted when the animal was dead after the acoustic experiment was completed. The total length is the length from the tip of the mantle to the tip of the arms when the squid is placed flat on a surface. The mantle width is the width of the widest portion of the mantle on the dorsal side. The mantle length is the length between the two ends of the mantle on the dorsal side. Two numbers in the measured angle of orientation indicate that acoustic measurements were conducted twice on the same individual. The calculated weight was calculated using the published length-weight relationship for L. pealeii (Lange and Johnson, 1981).

Loading

Article metrics loading...

/content/asa/journal/jasa/131/6/10.1121/1.3701876
2012-06-14
2014-04-25
Loading

Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Orientation dependence of broadband acoustic backscattering from live squid
http://aip.metastore.ingenta.com/content/asa/journal/jasa/131/6/10.1121/1.3701876
10.1121/1.3701876
SEARCH_EXPAND_ITEM