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| Titel |
Frequency analysis and data correlation for beam displacement measurements based on the ISTIMES campaign in Montagnole |
| VerfasserIn |
S. Nordebo, M. Gustafsson, J. Dumoulin, A. Perrone, S. Pignatti, F. Soldovieri |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061527
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| Zusammenfassung |
| Time-frequency analysis is an interdisciplinary subject, which originates from mathematics,
signal analysis and physics (Grochenig, 2001). From a signal theoretical and mathematical
point of view the primary purpose has been to understand how signals, operators and other
mathematical objects can be understood simultaneously in the time and frequency variables,
which correspond to the phase space variables in physics (Grochenig, 2001; Claasen, 1980).
Perhaps the most popular time-frequency representations are the short-time Fourier
transform (STFT) and the Wigner distribution (Grochenig, 2001). Their common feature
is to localize a function before taking the Fourier transform, thereby obtaining a
time-frequency representation. Here, we employ the classical Kaiser window (Kaiser
and Schafer, 1980) which is well known in spectrum analysis, since it provides
a flexible approach to control the frequency resolution as well as the amplitude
dynamics (sidelobe rejection) for a given measurement interval (or resolution) in
time.
In this contribution, we employ frequency analysis and data correlation for
beam displacement measurements based on the ISTIMES campaign (Proto et al.,
2010) conducted at the rock fall test center in Montagnole, France, on October
14, 2010. Several test cases are considered based on direct and indirect impact
from a steel sphere dropped on a reinforced concrete beam. Several measurement
technologies were used to measure the deformation of the beam based on IRT (InfraRed
Thermography), GBSAR (Ground Based Synthetic Aperture Radar), and ODM (Optical
Diode Measurements).
A time-frequency analysis was used to analyze the evolution of the resonance frequencies
of the beam. A short-time cross-correlation followed by Fourier transformation was used to
integrate data based on two different signal sources (sensor technologies). The results were
compared to a frequency analysis based on video data and image processing to yield a
high-accuracy reference measurement.
Even though the time-frequency analysis and data correlation techniques are able to
indicate a certain time-dependent behavior of the beam resonances, these results are difficult
to interpret due to several uncertainties that are detected in the measurement data. On the
other hand, all measurement techniques were consistent and agreed with the reference
measurement on a slight decrease in the beam resonant frequency for consecutive drops with
the steel sphere.
Acknowledgement
The research leading to these results has received funding from the European Community’s
Seventh Framework Programme (FP7/2007-2013) under Grant Agreement no 225663.
References
[1]   K. H. Grochenig. Foundations of time-frequency analysis. Birkhauser, 2001.
[2]   T. A. C. M. Claasen and W. F. G. Mecklenbräuker. The wigner distribution
– a tool for time-frequency signal analysis i–iii. Philips J. Research,
35:217–250,276–300,372–389, 1980.
[3]   J. F. Kaiser and R. W. Schafer. On the use of the Io-sinh window for spectrum
analysis. IEEE Trans. Acoust., Speech, and Signal Processing, 28(1):105–107,
1980.
[4]   M. Proto, M. Bavusi, R. Bernini, L. Bigagli, M. Bost, F. Bourquin, L.M.
Cottineau, V. Cuomo, P. Della Vecchia, M. Dolce, J. Dumoulin, L. Eppelbaum,
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S. Nordebo, F. Pacini, A. Palombo, S. Pascucci, A. Perrone, S. Pignatti, F.C.
Ponzo, E. Rizzo, F. Soldovieri, and F. Taillade. Transport infrastructure
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Sensors, 10:10620–10639, 2010. |
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