Simultaneous detection of density, moisture content and fiber direction of wood by THz time-domain spectroscopy

Autor: Moe Kashima, Satoru Tsuchikawa, Tetsuya Inagaki
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Journal of Wood Science, Vol 66, Iss 1, Pp 1-8 (2020)
Druh dokumentu: article
ISSN: 1435-0211
1611-4663
60291788
DOI: 10.1186/s10086-020-01874-3
Popis: Abstract In the wood product-manufacturing process, the physical properties of wood must be monitored. The terahertz (THz) radiation has a high potential for sensing and imaging wood with a good spatial resolution. This study demonstrates the simultaneous prediction of the density, moisture content, and fiber direction of wood, which are important in determining the wood quality, using THz time-domain spectroscopy. We measured the spectra of 12 kinds of wood at various moisture contents while rotating the sample against the THz wave polarization. The fiber direction was predicted by observing the birefringence, which is the optical property of a material, in which the refractive index depends on the polarization direction. The density and the moisture content were predicted by multiple linear regression using the refractive indices and absorption coefficients obtained from the THz measurement. In a series of THz measurements, we successfully identified the wood fiber direction with an R 2 of 0.90 and a root mean square error (RMSE) of 16.51° (total measured range = 0–170°), the density with an R 2 of 0.97 and an RMSE of 0.022 (total measured range = 0.25–0.67 g/cm3), and the moisture content with an R 2 of 0.78 and an RMSE of 4.06 (total measured range = 0.00–30.98%).
Databáze: Directory of Open Access Journals
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