High power ultrasonic transducers are widely used for detecting objects and measuring distances, etc. In actual applications, for the air coupling ones the impedance mismatch between the transducer surface and air is large, so there is only a small amount of energy transmitted. Most of the energy loss occurs during the transformation of energy from the transducer radial cone to the air. The purpose of this study is to investigate different designs of the radial cone of the transducer and analyze their vibration in order to suggest design variations for improved vibration amplitudes. Concerning a piezoelectric ceramic transducer, we focus on two parameters of the transducer radial cone. This report presents schemes for increasing pressure levels.

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The electric field tweezers system was employed to excite the surface acoustic mode vibration on the surfaces of gelatin gel and sol. Electric field is applied by a needle electrode set just above the sample surface, which picks up the surface of the dielectric materials. The amplitude of the surface deformation gives the restoring force of surface tension and shear elasticity, while the time constant of the deformation yields by the viscosity. We determined the shear elasticity, viscosity and the surface tension uniquely by measuring the dynamic behavior of the surface changing the gap distance between the needle electrode and the surface.

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This research is focused on investigating the dispersion behaviors of guided waves (GW) propagating in Zircaloy cladding tubes. Theoretical models are used to model the dispersions of GW propagating along the circumferentail direction, and along the axial direction as well. It is found out that these two sets of dispersion are very close when the wall thickness is small, and show significant difference as the wall thickness increases. A laser ultrasound technique is used to measure the dispersions of GW propagating along the circumferential and axial directions. The theories are well supported by the measurements.

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In this research, a laser ultrasound technique (LUT) is reported for nondestructive characterization of hydride rims (HR) in Zircaloy cladding tubes. With the LUT, guided waves propagating in the Zircaloy tubes with different HR thickness are generated and detected remotely by optical means. By measuring the dispersive ultrasonic wavespeeds with the LUT, combining with the inversion technique, relations between the dispersion relations and thickness of HR are established. Good accuracy in measuring the HR thickness is demonstrated with this combined LUT with inversion algorism technique.

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This paper proposes a combined numerical and experimental investigation for the dispersion behaviors of antisymmetric flexural (ASF) modes propagating along wedges coated with film. The investigated parameters include the material properties and geometrical features of wedge, mechanical properties of the film.

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Propagation behaviors of wedge waves (WW) propagating along the apex of a piezoelectric wedges with fluid loading are investigated. WW propagating in isotropic materials is reported, however, not for the piezoelectric materials with extra effects of anisotropy and piezoelectricity. While fluid loading effects are considered, the WW problem could be more complex. A combined experimental/numerical study is used to characterize the effects of anisotropy and fluid loading effects on WWs propagating along piezoelectric wedges.

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This research is focused in the measurement and modeling for the dispersion relations of Lamb waves propagating in LiNbOS and LiTaO3 wafers. A theoretical model based on a stiffness matrix method with recursion computation algorism is used to provide numerical calculations for the dispersion relations. Also, a dry, noncontact laser ultrasound technique is used to measured dispersion multi-mode dispersion relations. For all the experiments, the measured dispersion curves show good agreement with the theoretical calculation, indicating the reliabilities in the measurement and modeling.

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From a new scientific viewpoint, research of potentiality of second order harmonic in nonlinear surface acoustic wave was done. In this context, experimental facts which were on envelope velocity, on full width at half maximum of the envelope profile, and also on envelope profile were discussed. From experiment fact on head-on clash of two second harmonics, it was just a kind of soliton.

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A multi-wavelength fiber optic tunable laser is proposed for use in a fiber Bragg grating (FBG) vibration sensor array. The laser employs a semiconductor optical amplifier (SOA) as a gain medium, and FBGs as wavelength selection components. Since the SOA is an inhomogeneous broadening gain medium, stable multi-wavelength oscillation can be realized. In this configuration, oscillation outputs respectively serve as optical sources of the wavelength-division multiplexed (WDM) FBG sensor array in which multiple vibrations applied to the sensing FBGs can be detected at the same time. In addition, by controlling strain to the respective tuning FBGs the tunable operation can be achieved for the temperature compensation of the sensor outputs. For the demonstration of the performance principle of the sensor system, we have fabricated a dual-wavelength tunable laser and arranged two FBG vibration sensors in serial. In the experiment, the thermally stabilized WDM operation of the sensor array has been successfully demonstrated.

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A novel wavelength division multiplexing fiber Bragg grating (FBG) underwater acoustic sensor array using electric feedback circuit is proposed in order to realize fast temperature response. To evaluate temporal response of thermally stabilizing system, we applied step-like temperature variation (25℃→85℃) to the sensor. The time constant of the system is measured to be 1.9 s. Because the time constant in the previous system is 13 s, the temporal-response of the sensor proves to be seven times faster than the previous one.

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In an ordinary way, the piezoelectric displacement is proportional to the external electrical field. Even with the polarization reversal, the remanant piezoelectric displacement does not change. It is correct when the piezoelectric butterfly curve is symmetric with the piezoelectric displacement axis. However, with the voltage offset, which comes from an electrical imprint, the remanant piezoelectric displacement has two stable states. In this situation, without the electrical field, the actuator can have two stable positions depending on the polarization direction. This phenomenon enables us to use this actuator as a shape memory switch that does not require electrical supply to keep on and off positions, for example. To change the polarization direction, only pulse shaped voltage is required, hence a small electrical consumption and a simple driving circuit can be realized.

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An imaginary part of complex Young's modulus of silicone rubber has been investigated experimentally and theoretically using a quartz-crystal tuning-fork tactile sensor. The impedance change (ΔR) of the tactile sensor at resonant vibration 32.48 kHz is measured when the tactile sensor is in contact with the center of the surface of rectangular silicone rubber plate in the manner that the thickness of silicone rubber is 5, 10, 15, 20, 25, and 30 mm with 60 mm length of each side of it. The measurement of ΔR against the thickness of silicone rubber using a quartz-crystal tuning-fork tactile sensor includes the information of viscoelasticity of it as the damping factor a for a longitudinal plane transmitting wave in three layers (the sensor's base, silicone rubber, neoprene rubber). We can determine an imaginary part of the complex Young's modulus of silicone rubber by use of the value of a.

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A novel measurement method of paper's surface smoothness and roughness is established by use of a quartz-crystal tuning-fork tactile sensor. When the sensor's base gets brought into contact with paper's surface placed on neoprene rubber with 2 mm thick through 10 mm square hole dug in neoprene rubber covering paper under application of a 10 g load of the sensor, the impedance increase of the quartz-crystal tuning-fork tactile sensor at resonance vibration has been found to correspond with sensory test values of the surface smoothness and roughness measured by 8 testers. This sensor functions as a paper-quality sensor capable of sensing the paper's surface roughness.

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Cellular-phone markets are moving quite aggressively towards module integration and as a result, the miniaturization of devices has been accelerated. Especially SAW filters, which are the key devices in the RF parts, are demanded to realize a small size, low profile with high reliability performance.Conventional SAW filters use a HTCC package with cavity structure and metal sealing to obtain high reliability performance This structure restricts the miniaturization of SAW filters. In order to reduce size, HTCC without cavity structure and resin sealing are commonly used. However, this structure dose not contribute to the high reliability performance.This paper describes the realization of a new miniaturized SAW filter which is a combination of HTCC without cavity structure and metal sealing by using a unique packaging technique to achieve a low profile with high reliability performance. The technique has been realized by using cluster sealing with solder. The optimization of the PKG design and sealing pressure was performed in solder sealing. In addition, by using plating in the outer coating, a high reliability performance can easily be achieved. Results of reliability testing including mechanical, electrical and moisture sensitivity will be discussed.

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Using flattened SiO_2/Cu-electrode/36〜48°LiTaO_3 structure, small size (5×5mm^2) surface acoustic wave (SAW) duplexer with a good temperature coefficient of frequency (TCP) for US-PCS was realized. However, smaller duplexer has been strongly required. Using flip-chip bonding process and flattened SiO_2/Cu-electrode/128°YX-LiNbO_3, which has larger coupling factor than above-mentioned substrate, smaller sized (3×2.5mm^2) SAW duplexer with a good TCP has been realized.

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