Spherical Harmonic Representation for Dynamic Sound-Field Measurements

A spiral sound wave transducer comprised of longitudinal vibrating elements has been proposed. This transducer was made from eight uniform radial distributed longitudinal vibrating elements, which could effectively generate low frequency underwater acoustic spiral waves. We discuss the production theory of spiral sound waves, which could be synthesized by two orthogonal acoustic dipoles with a phase difference of 90 degrees. The excitation voltage distribution of the transducer for emitting a spiral sound wave and the measurement method for the transducer is given. Three-dimensional finite element modeling (FEM)of the transducer was established for simulating the vibration modes and the acoustic characteristics of the transducers. Further, we fabricated a spiral sound wave transducer based on our design and simulations. It was found that the resonance frequency of the transducer was 10.8 kHz and that the transmitting voltage resonance was 140.5 dB. The underwater sound field measurements demonstrate that our designed transducer based on the longitudinal elements could successfully generate spiral sound waves.

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Constraining GRACE-derived cryosphere-attributed signal to irregularly shaped ice-covered areas

The Cryosphere ◽

10.5194/tc-7-1901-2013 ◽

2013 ◽

Vol 7 (6) ◽

pp. 1901-1914 ◽

Cited By ~ 3

Author(s):

W. Colgan ◽

S. Luthcke ◽

W. Abdalati ◽

M. Citterio

Keyword(s):

Monte Carlo ◽

Mass Loss ◽

Mass Balance ◽

Spherical Harmonic ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Caps ◽

Ice Coverage ◽

Ice Sheet Mass Balance ◽

Harmonic Representation

Abstract. We use a Monte Carlo approach to invert a spherical harmonic representation of cryosphere-attributed mass change in order to infer the most likely underlying mass changes within irregularly shaped ice-covered areas at nominal 26 km resolution. By inverting a spherical harmonic representation through the incorporation of additional fractional ice coverage information, this approach seeks to eliminate signal leakage between non-ice-covered and ice-covered areas. The spherical harmonic representation suggests a Greenland mass loss of 251 ± 25 Gt a−1 over the December 2003 to December 2010 period. The inversion suggests 218 ± 20 Gt a−1 was due to the ice sheet proper, and 34 ± 5 Gt a−1 (or ~14%) was due to Greenland peripheral glaciers and ice caps (GrPGICs). This mass loss from GrPGICs exceeds that inferred from all ice masses on both Ellesmere and Devon islands combined. This partition therefore highlights that GRACE-derived "Greenland" mass loss cannot be taken as synonymous with "Greenland ice sheet" mass loss when making comparisons with estimates of ice sheet mass balance derived from techniques that sample only the ice sheet proper.

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Cerebral asymmetry in temporal lobe epilepsy detected by weighted spherical harmonic representation

NeuroImage ◽

10.1016/s1053-8119(09)71880-4 ◽

2009 ◽

Vol 47 ◽

pp. S173

Author(s):

B. Lv ◽

H.G. He ◽

M. Li ◽

J.J. Lu ◽

W.J. Li ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Spherical Harmonic ◽

Cerebral Asymmetry ◽

Harmonic Representation

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An innovative probe microphone design for use in high‐frequency sound field measurements

The Journal of the Acoustical Society of America ◽

10.1121/1.411657 ◽

1995 ◽

Vol 97 (5) ◽

pp. 3252-3252

Author(s):

Sean M. Connelly ◽

Linda P. Franzoni

Keyword(s):

High Frequency ◽

Sound Field ◽

Field Measurements ◽

High Frequency Sound ◽

Frequency Sound

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Identification of material properties from full field measurements of a sound field interacting with a solid

EPJ Web of Conferences ◽

10.1051/epjconf/20100637004 ◽

2010 ◽

Vol 6 ◽

pp. 37004

Author(s):

S. Vanlanduit ◽

C. Vuye ◽

R. Longo ◽

P. Guillaume

Keyword(s):

Material Properties ◽

Sound Field ◽

Field Measurements ◽

Full Field

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Nozzles, turbulence, and jet noise prediction

Journal of Fluid Mechanics ◽

10.1017/jfm.2018.823 ◽

2018 ◽

Vol 860 ◽

pp. 1-4 ◽

Cited By ~ 2

Author(s):

Jonathan B. Freund

Keyword(s):

Prediction Accuracy ◽

Jet Noise ◽

Sound Field ◽

Field Measurements ◽

Detailed Comparison ◽

Large Eddy Simulations ◽

Noise Prediction ◽

Large Eddy ◽

Modelling Procedure ◽

Flow Turbulence

Jet noise prediction is notoriously challenging because only subtle features of the flow turbulence radiate sound. The article by Brès et al. (J. Fluid Mech., vol. 851, 2018, pp. 83–124) shows that a well-constructed modelling procedure for the nozzle turbulence can provide unprecedented sub-dB prediction accuracy with modest-scale large-eddy simulations, as confirmed by detailed comparison with turbulence and sound-field measurements. This both illuminates the essential mechanisms of the flow and facilitates prediction for engineering design.

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