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Stability of monitoring weak changes in multiply scattering media with ambient noise correlation: Laboratory experiments
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10.1121/1.3125345
/content/asa/journal/jasa/125/6/10.1121/1.3125345
http://aip.metastore.ingenta.com/content/asa/journal/jasa/125/6/10.1121/1.3125345

Figures

Image of FIG. 1.
FIG. 1.

Gray line: acoustic field transmitted through the 64 mm thick bubble-gel mixture (in normalized amplitude). Black broken line: 2D diffusion equation for and .

Image of FIG. 2.
FIG. 2.

Experimental setup. Left: the active experiment in the pulse-echo configuration. Right: the passive experiment in the transmission configuration before autocorrelation.

Image of FIG. 3.
FIG. 3.

Example of two records and acquired at the same position (same transducer) but at two different dates. Between the two acquisitions, the temperature has increased by , which is hardly visible in the early part of the record (inset between 10 and ) but very clear in the late coda (inset between 42 and ).

Image of FIG. 4.
FIG. 4.

Delay time evaluated for different lapse times in the coda from the doublet code. The broken line is the linear trend whose slope yields between and .

Image of FIG. 5.
FIG. 5.

The correlation coefficient is evaluated at two temperatures for and 3 in the range. The maximum, obtained for a relative velocity change of , is indicated by the vertical arrow. It corresponds to an increase in temperature of . Theory is from Eq. (5).

Image of FIG. 6.
FIG. 6.

The correlation coefficient is evaluated at two temperatures and 3 in the range, for various SNRs. Crosses indicate experimental data. The gray background indicates expected fluctuations [Eq. (11)] around the theory [Eq. (10)]. The proper velocity change is found in all cases, though a slight difference is visible for .

Image of FIG. 7.
FIG. 7.

Relative velocity changes evaluated from the stretching (left) and for the doublet (right) technique for various SNRs. The actual is satisfyingly retrieved for any with the first technique, not with the second.

Image of FIG. 8.
FIG. 8.

Comparison of the pulse-echo data obtained in the active experiment and the average autocorrelation .

Image of FIG. 9.
FIG. 9.

Relative velocity changes evaluated from the active (pulse-echo with ) and the passive (autocorrelation with ) setup.

Image of FIG. 10.
FIG. 10.

(a) The seismic noise source structure changes from one date to another. (b) Analogous laboratory experiment: Two sets of sources are chosen at two different dates.

Image of FIG. 11.
FIG. 11.

Relative error in the estimation of , versus the ratio of unchanged-to-total amount of noise sources (-axis in logarithmic scale).

Tables

Generic image for table
TABLE I.

Comparison of the physical parameters between seismology and ultrasound.

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/content/asa/journal/jasa/125/6/10.1121/1.3125345
2009-06-01
2014-04-16
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Stability of monitoring weak changes in multiply scattering media with ambient noise correlation: Laboratory experiments
http://aip.metastore.ingenta.com/content/asa/journal/jasa/125/6/10.1121/1.3125345
10.1121/1.3125345
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