音波を用いたパイプの不連続部検出

概要

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There are many kinds of life infrastructure such as gas and water pipes, communication and power cables, are buried in the floor or wall of buildings. The layout information of these structures is very important in maintenance and repairing constructions. It is expected that by launching an acoustic wave directly into a pipe, the position of the discontinuities of the pipe can be estimated from the reflective waves precisely. In this paper, detection of the discontinuities of gas pipe is studied experimentally with an acoustic chirp signal. In order to distinguish L-junction and T-branch, the propagations of an acoustic wave are computed and studied by FDTD analysis. A differential method is proposed to reduce the directive wave. The experimental results show that the method improved distinctness of the reflective signals. It is also confirmed experimentally that the sidelobes of the compressed pulse are decreased by multiplying a Hamming window function to the output chirp signal. The proposed system is able to detect the discontinuities in 36m long gas pipe, and distinguish the L-junction and T-branch according to their reflection characteristics.
2006-11-01