1997 Fiscal Year Final Research Report Summary
Research on Electrical Resistivity Prospection for Archeology
| Project/Area Number |
05205102
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Research Institution | Ibaraki University |
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Principal Investigator |
AGU Masahiro Ibaraki Univ., Dept.of Media and Telecommunications Eng., Professor, 工学部, 教授 (10016462)
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| Co-Investigator(Kenkyū-buntansha) |
AKABANE Hideo Ibaraki Univ., Dept.of Media and Telecommunications Eng., Lecturer, 工学部, 講師 (50192886)
OKAMOTO Yoshiwo Chiba Inst.of Tech., Dept.of Electric Eng., Professor, 工学部, 助教授 (20152358)
NOGUCHI Koji Waseda Univ., Dept.of Mineral Resources Engineering, Professor, 理工学部, 教授 (50147948)
TERAMACHI Yasuaki Univ.of Industrial Tech., Dept.of Computer and Information Sci., Professor, 教授
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| Project Period (FY) |
1992 – 1996
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| Keywords | prospection / resistivity / electrode / archaeology / apparent resitivity / theoretical calculation / 鏡像法 |
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| Research Abstract |
1. A new type electrical resistivity prospecting system for archeological targets
We have developed a new resistivity measuring system for archeological prospection which is composed of the dual phase lock-in amplifier, constant ac current source, electrodes selectors, and a hand held computer for automatic data acquisition. Maximum number of electrodes is 256. This system is suitable for japanese archeological sites. Displacement between electrodes is asumed to be in the range of 1 meter to several meters. Then suitable depth for prospection is less than ten meters. The lock-in amplifier is introduced to reduce noise level and measuring time.
2. Inverse problems analysis and a compensation of surface irregularities.
2-1. Delopment of efficient caluculation method.
If ground surface is flat and smooth, ground surface can be eliminated from the system by combinning a boundary element method and a method of images. In this case, it is not necessary to take into account boudary conditions for
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very far places on the ground. Then the calculation time becomes shorter and the accuracy of calculation increases.
2-1. Compensation of ground surface irreguralities.
Ooyasuba-Kofun is an keyhole tomb with quadrangular rear mound, located at Kouriyama city in Fukushima prefecture. There were many concavities about one to two meters in diameters on the mound top, even though it is almost flat. It was found that these concavities deeply affected the apparent resistivity values. Thus, it was tried to eleminate effects of concavities. Apparent resistivity values on the flat surface with a hemispheric concavity can be calculated theoretically. Then, it is easy to aliminate the effect of concavity, if we devide measured resistivity values by caluculated values. It was found that there was place whose apparent resistivity was lower than that of surounding area even after compensations. Afterword, itwas found that there was a clay coated wood coffin just at this place by the excavation of the Kouriyama city's board of education. Less
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