We discuss the cooling effect of a loop-tube-type thermoacoustic cooling system especially emphasizing the effect of the heat pump placed in the resonance tube. The temperature decrease for the loop tube connected by the resonance tube with the heat pump placed in the resonance tube is 25 ℃, while the temperature decrease for the loop tube without the resonance tube with the heat pump placed in the loop tube is only 9 ℃. This is the effect of the heat pump placed in the resonance tube. The heat pump placed outside of the loop tube suppresses an influence of not only the viscosity effect of the heat-pump stack but also the undesirable heat flow caused by the acoustic streaming. According to this, the connection of the resonance tube contributes to an improvement. Consequently, the heat pump placed in the resonance tube connected to the loop tube improves the cooling effect of the loop tube.

View full abstract

An integration method of SSBL and INS was introduced. Simulation and experimental results were shown and it was shown that the method works well. The estimation errors due to the signal distortion caused the Doppler shift and the ISI were considered. Especially the error of SSBL estimation due to the ISI is generated because of the continuous acoustic signal that is distinguished for the proposed method. Nevertheless the proposed method is useful. In the future adaptive compensation of the system error and multiple access will be considered.

View full abstract

By using the micro-Brillouin scattering method, we successfully observe the temperature dependence of Brillouin shift and FWHM in HEWL crystals. We observe glass transition of the protein crystal and alcohol solution. The relaxation process originate from cooperative motion is clearly observed. The comparison of the relaxation processes of three kinds of HEWL crystal will be discussed.

View full abstract

A hydrogen sensor using ultrasonic was studied. Sound velocity of hydrogen is about four times larger than that of the air. Therefore, it is possible to measure hydorgen contents in the air by measuring the sound velocity. We have showed that it is possible to measure up to near 100ppm hydrogen content in the air by measuring the sound velocity at 330kHz of ultrasonic.

View full abstract

In the reflection point search using rectangular sound sources, a rectangular transducer array with small number of element was introduced, and the improvement on the search result was attempted. Results of numerical calculations show that there is the position where the search result is improved. However, the position where the search result is not improved also exists. In order to attempt the improvement on the search results, it is necessary to conduct further examinations with respect to the conditions of the reflection point and sound sources.

View full abstract