| Presentation | 1999/12/21 Nonlinear phenomena in ultrasound beams Tomoo Kamakura, Kenichi Aoki, Hideyuki Nomura, |
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| PDF Download Page | PDF download Page Link |
| Abstract(in Japanese) | (See Japanese page) |
| Abstract(in English) | Sound pressure amplitudes of the first three harmonics in finite-amplitude CW ultrasound beams are measured along and across the beam axis in fresh water. The sound source is a 1.8MHz focused transducer with a circular aperture of 71mm in diameter and a focal length of 75mm. The source pressure amplitude is supposed to be distributed uniformly. The aperture half-opening angle of 28.3° exceeds the upper limit of the applicability of the parabolic or paraxial approximation, so the present authors propose a beam model equation using the oblate spheroidal coordinate system for theoretical prediction. Numerical solutions of the model equation are overall in good agreement with the experiment. Thus the supported validity of the model equation allows us to further study nonlinear propagation of ultrasonic pulses from a strongly focusing source. It has been determined numerically that the direct wave from the center of the source has a crucial effect on forming a shock-like spike in the post-focal region. |
| Keyword(in Japanese) | (See Japanese page) |
| Keyword(in English) | nonlinear acoustics / focused beam / harmonic generation |
| Paper # | US99-69 |
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| Conference Information | |
| Committee | US |
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| Conference Date | 1999/12/21(1days) |
| Place (in Japanese) | (See Japanese page) |
| Place (in English) | |
| Topics (in Japanese) | (See Japanese page) |
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| Paper Information | |
| Registration To | Ultrasonics (US) |
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| Language | JPN |
| Title (in Japanese) | (See Japanese page) |
| Sub Title (in Japanese) | (See Japanese page) |
| Title (in English) | Nonlinear phenomena in ultrasound beams |
| Sub Title (in English) | |
| Keyword(1) | nonlinear acoustics |
| Keyword(2) | focused beam |
| Keyword(3) | harmonic generation |
| 1st Author's Name | Tomoo Kamakura |
| 1st Author's Affiliation | The University of Electro-Communications() |
| 2nd Author's Name | Kenichi Aoki |
| 2nd Author's Affiliation | The University of Electro-Communications |
| 3rd Author's Name | Hideyuki Nomura |
| 3rd Author's Affiliation | The University of Electro-Communications |
| Date | 1999/12/21 |
| Paper # | US99-69 |
| Volume (vol) | vol.99 |
| Number (no) | 527 |
| Page | pp.pp.- |
| #Pages | 8 |
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