| Project/Area Number |
10650404
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Measurement engineering
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| Research Institution | The University of Electro-Communications |
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Principal Investigator |
KAMAKURA Tomoo Department of Electro-Communication, The University of Electro-Communications, Professor, 電気通信学部, 教授 (50109279)
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| Co-Investigator(Kenkyū-buntansha) |
鎌倉 友男 電気通信大学, 電気通信学部, 教授 (50109279)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | hydrophone / reciprocity calibration / nonlinear acoustics / waveform distortion / harmonics / 校正 |
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| Research Abstract |
Two different kinds of miniature PVDF hydrophones of 0.6mm and 1mm in diameter have been calibrated for their sensitivity responses using two methods. One of which is based on a conventional methodology, the reciprocity calibration, and the other is based on nonlinear propagation of sound beams. Specifically, ultrasound beams of finite amplitude generate waveform distortions due to the inherent nonlinearity of a medium, and plenty of harmonics appear significantly in the beam. The magnitudes of individual harmonic components are theoretically predicted by a model equation that we propose for precise description of nonlinear sound beams. The harmonic pressures are strongly dependent on source conditions such as driving frequency and source pressure level. The sensitivity response of output voltage to pressure at the fundamental frequency is measured by the reciprocity method. The information of the fundamental frequency source conditions uniquely determines all the pressure magnitudes of higher harmonics. By detailed comparison of harmonic pressures between experiment and theory, the calibration in the frequency range of 2.5 to 20MHz has been performed for the two different hydrophones. It has been concluded that the sensitivity responses for the hydrophones are overall in good agreement with the attached data sheets within 1.5dB differences.
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