| Budget Amount *help |
¥3,410,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
1: The first result presents an autonomous directivity microphone system based on the newly proposed spatio-temporal blind source separation. The blind source separation principally uses no a priori knowledge about parameters of convolution, filtering and mixing. In the simplest case of the blind source separation problems, observed mixed signals are linear combinations of unknown mutually statistically independent, zero-mean source signals. The blind signal separation algorithm utilizes the linearity among the four signals: (1) the sound pressure, (2) x, (3) y, and (4) z-directional particle velocities, all of which are governed by the wave equation and the equation of motion. The proposed method, therefore, has an ability to simplify the convolution blind source separation problems into the instantaneous blind source separation over the spatiotemporal gradient space. 2. The second result presents an opt-acoustical measurement of non-invasive measurement over the acoustic wave-field.
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In this study, a novel method for grading vector measurement of the sound pressure-field is proposed. The proposed method has an ability to capture the projection of the gradient vector of acoustic wave-field through the eccentricity of the 0th-order Fraunhofer diffraction. In this study, the theoretical analysis of the process of the above projection is discussed and their physical meanings are investigated through numerical experiments and acousto-optical experiments. 3. The third result presents the eigenvalue imaging method to be independent of frequency and phase velocity and to characterize the wave field where incident and scattered waves overlap each other. For detecting the defects, spatio-temporal gradient analysis based on the linear dependency among the vertical displacement, the vertical particle velocity, and a pair of shear strains is used. The following conclusions and remarks are conducted: (1) Eigenvalue Imaging based on the spatio-temporal gradient analysis is proposed as a novel NDE method. (2) The third eigenvalue detects a wave scattered by defects. (3) The fourth eigenvalue has an ability to localize defects. Less
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