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Nishida, Akemi; Suzuki, Yoshio; Hayashi, Sachiko; Kunitomo, Takahiro*; Kumazawa, Mineo*; Hasada, Yoko*
Dai-58-Kai Riron Oyo Rikigaku Koenkai Koen Rombunshu (CD-ROM), 2 Pages, 2009/06
ACROSS (Accurately Controlled, Routinely Operated, Signal System) is such a precise metrology of frequency response characteristics that the accurately controlled sinusoidal waves (acoustic comb) is used as an input to the linear dynamic system, and induced vibration as an output is measured by the accelerometers synchronized accurately to input. This technology has been developed to be used on a routine basis for the subsurface structural analysis and state-monitoring of the geological targets. We discuss the theoretical background and the related subjects of applying this method to the artificial structures. Further we report the preliminary test experiments and results on the steel beam structure installed at TGC, JAEA.
Nishida, Akemi; Suzuki, Yoshio; Hayashi, Sachiko; Kunitomo, Takahiro*; Kumazawa, Mineo*; Hasada, Yoko*
Dai-58-Kai Riron Oyo Rikigaku Koenkai Koen Rombunshu (CD-ROM), 2 Pages, 2009/06
The transfer function data in frequency domain acquired by ACROSS is analyzed by SOMPI method, which is based essentially on AR model as a discrete equivalent of linear dynamic system. The analysis is made in two steps, time domain analysis and space-wave number domain both in a consistent way as a linear dynamic system. We have derived an accurate set of vibration characteristics including attenuation and also the local characteristics such as wave propagation within the structural units and their interactions. Detection of small change in the structure is demonstrated by introduction of very precise measurement by ACROSS combined with the data analysis by SOMPI method.
Nishida, Akemi; Suzuki, Yoshio; Hayashi, Sachiko; Kunitomo, Takahiro*; Kumazawa, Mineo*; Hasada, Yoko*
Dai-58-Kai Riron Oyo Rikigaku Koenkai Koen Rombunshu (CD-ROM), 2 Pages, 2009/06
Reliable and strict evaluation is demanded to guarantee the safety of nuclear facilities against earthquake vibrations, in particular. Usually the necessary data have been acquired by determining the natural frequency and attenuation characteristics by utilizing microseisms as an excitation agent of the vibration. The presence of measurement errors and estimation bias has been inherent and problematic in this approach. Here we try to make a break through by introducing ACROSS technology, which have been providing very accurate and reliable data on subsurface, i.e., geologic targets. In this paper, we report the relevant strategy, general concept of this approach. The technical subjects on measurement system and also a potential method of analyzing data are reported in the subsequent two papers.