| Co-Investigator(Kenkyū-buntansha) |
ADACHI Kazunari University of Yamagata. Department of Engineering. Associate Professor, 工学部, 助教授 (00212514)
TAMURA Yasutaka University of Yamagata. Department of Engineering. Associate Professor, 工学部, 助教授 (40171904)
HACHIYA Hiroyuki University of Chiba. Department of Engineering. Associate Professor, 工学部, 助教授 (90156349)
MOTOOKA Seiichi Chiba Institute of Technology. Department of Engineering. Professor, 工学部, 教授 (60083862)
SUGIMOTO Tsuneyoshi Toin University of Yokohama. Department of Engineering. Lecturer, 工学部, 講師 (80257427)
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| Research Abstract |
This research group comprises two sub-groups. the one is organized for the research on the method for investigating buried cultural assets, namely remains in tumuli and ruins of ancient residences and kilns, with the aid of sound ranging thchniques. The other is that for the development of the non-invasive technique for large wooden or stone structures with archeological interest such as 'torii' or gates of Shinto shrines using ultrasonic computed tomography (CT). The members of the former sub-group are Okujima, Sugimoto, Motooka and Hachiya, and those of the latter one Adachi and Tamura.
[Development of acoutical underground investigation method]
From the experiments conducted until the last fiscal year, we have already found that use of shearwaves allow us to visualize objects buried in the shallow ground. A source for transmitting shearwaves and a geophone for receiving reflective waves from underground and its setting on the ground surface were also studied. In the fiscal year, the p
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riority of research has been given to improvement of the visualization method used in our underground investigation system. For this purpose, we have studied the method in the following aspects :
(1) Opimum arrangement of the soundsource-geophone array for a apecific detection range.
(2) Signal processing for imaging of wide depth range.
(3) Image processing for good human recognition of objects.
The field works have been done at several sites of ruins. Clear underground images which can be used for practical archeological prospection have been reconstructed from the data obtained in those field works and experiments by means of the image processing method developed in this research.
[Development of ultrasonic time-of-flight CT for archeological inspection]
From the experiments conducted until the last fiscal year, we have already confirmed that ultrasonic time-of-flight CT can be the effective technique for imaging of the inner construction of wooden structures by using the prototype equipment. Major points of progress concerning the development of ultrasonic CT used for archeological inspection in the fiscal year are as follows :
(1) A Multi-channel receiving system with high sensitivity and high perpormance for receiving minute ultrasonic pulse signals has been developed.
(2) Ultrasonic signal receivers made of PVDF film have also been developed.
(3) We have devised a method for processing the CT image with reasonable treatment of ultrasonic transmission paths for which the time-of-flight data cannot taken. With the use of this method, artifacts due to the large TOF data arbitrarity substituted for that of such paths can be eliminated from the image. Less
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