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| | Abstract | | Ultrasonic wave-transmission measurements on an ice-brine coexisting system were conducted to examine the influence of unfrozen brine in the pore microstructure on ultrasonic S-waves. We try to improve a method that derives a more accurate measurement of ultrasonic attenuation by using sweep-type signals. We obtained spectral amplitude of the sweep signal in frequency-time domain using the continuous wavelet transform and estimated attenuation in the time-frequency domain using the spectral-ratio method. Finally we calculated the attenuation of the S-wave in the ultrasonic frequency range --200 to 400 kHz-- using sweep signals through a liquid system to a solid-liquid coexistence system, changing its temperature from -3C to -15C. We concluded that further improvement to acquire higher S/N data is needed. |
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