A method to obtain flow vector mapping considering convective acceleration mapping evaluated from 2-dimensional ultrasonic Doppler information is proposed. Medical ultrasonic systems for 2-dimensional Doppler flow mapping are commercially available, so 2-dimensional Doppler information on flow can be gotten in real time. A method that deduces flow vector mapping from Doppler information about fluid flow was therefore developed to evaluate cardiac function quantitatively. A numerical example was shown for the laminar flow in a tube. Generalization of this method was suggested for application to other fields.

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A new method is proposed to estimate the shape of a pile by vibration analysis. This is the first method proposed for a pile-shape estimation, which can be used to diagnose the integrity of a pile with an enlarged, subterranean base. It is demonstrated, and verified by experimentation, that pile-shape can be estimated by using an acoustic tube model. Pile shape estimation by this method was found to be quite accurate for an experimental pile laid horizontally on ties, at ground level. This method could be used for estimating the shape of an underground pile, when the soil effect is removed from the measured vibration signal.

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The influence of shape and size of a dummyhead upon the sound reaching the ear is discussed. The Thévenin acoustic impedance and Thévenin pressure, which have been adopted as acoustical parameters for evaluating the effect of individually different shapes and sizes of the human head (K. Fukudome, Proc. 10th Int. Congr. Acoust.(Sydney) 1980), are numerically examined by using two types of model heads. The shape and size of the model heads, respectively a sphere and an oblate spheroid, were changed according to head circumference and the cephalic index of the somatometry of the head. As a result, it was found that the Thévenin acoustic impedance is hardly influenced by the shape and size of the model head. The influence of head shape and size upon the maximum of absolute value of log magnitude and phase of Thévenin pressure was illustrated in terms of an equal magnitude contour and an equal phase contour. A final discussion deals with regards for an average head in shape and size as a head which is acoustically standard.

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Analysis and experiment of the response of an electromagnetic pickup excited by a string vibration are made by use of the following assumptions. First, the inharmonicity exists in the string vibration because of the influence of the negative stiffness of the electromagnetic pickup. Secondly, the displacement of a string is not, however, affected by the negative stiffness. Thirdly, the damping coefficients are approximated based upon the measured values of some low frequency partials. The magnetic circuit and the characteristic equation are built up for analysis. The simulated results are in good agreement with the experimental results. The results also show that there are distortion components in the response, but their relative levels are very small. Furthermore, beats occur in the response. Its percentage of depth of beats is about 30.1 when it is picked up at the center point of a string.

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In the dialysis experiment where an artificial kidney was used as a model, and an aqueous solution of creatinine was used instead of blood, the clearance, dialysis efficiency, was improved remarkably by ultrasonic irradiation. The clearance increased with the ultrasonic level and reached the maximum value at a certain ultrasonic level. The maximum value of clearance was about 1.5 times as high as that without ultrasonic irradiation. The dialysis in this dialyzer model was treated with a simple transfer theory on the inside of the dialyzer tube, in the tube wall, and in the outer region of the tube considering the diffusion resistance respectively. The derived relation of clearance to the volume flow was compared with the experimental results. It has been deduced that the higher values of the clearance were due to the removal of the outer concentration boundary layer by ultrasonic cavitation and microstream. Thus, the predominated resistance was considered to be mainly due to that in the tube wall in this situation, and the value of diffusion coefficient was about 7.7×10^-7 cm²/s.

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A new configuration of acoustic echo canceller for multiple microphone teleconferencing systems is proposed. It is designed for use with microphones whose gains switch or vary during teleconferencing according to the talker. This system requires memory for multiple echo paths, which enables the updating of filter coefficients when an echo path is changed due to the switching of the actuated microphone during talker alternation. In comparison to the single echo path model which uses only adaptation, this method maintains echo cancellation during abrupt changes of the echo path when the microphone alternates between talkers. Also in comparison to direct microphone output mixing, this method reduces the stationary residual echo level by the reduction of acoustic coupling.

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A plain piston model is often not sufficient to describe the entire radiation characteristics of a ultrasonic transducer. In this report a transducer model is introduced, which bases on a decomposition of the transducer surface in concentric circular areas with uniform motion. A calibration procedure allows to compute the motion of these areas from the measured soundfield in a small number of spacial positions. The transient sound field at an arbitrary position is determined using these functions of motion.

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