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Automated low energy photon absorption equipment for measuring internal moisture and density distributions of wood samples

Automatische Feuchte- und Dichtemessung durch Absorption von Gammastrahlung niedriger Energie

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Abstract

Automated equipment for measuring the moisture and density distributions of wood samples was developed. Using a narrow beam of gamma rays, the equipment scans the wood samples, which are placed on the moving belt. The moisture measurement is based on the241Am photon absorption technique (59.5 keV), where the difference of the linear absorption coefficients of the moist and dry wood is measured. The method requires no knowledge of the thickness of the specimen. The density estimation method is based on the measurement of the linear attenuation coefficient of wood. Comprehensive software including image processing was developed for treatment of the numerical values of the measurements.

Zusammenfassung

Ein automatisches Gerät zum Messen der Feuchte- und Dichteverteilung in Holzproben wurde entwickelt. Mit einem eng gebündelten Gammastrahl werden dabei die Holzproben auf einem beweglichen Probentisch abgerastert. Die Feuchtebestimmung beruht auf der Photonenabsorption der241Am-Strahlung (59,5 keV), wobei die Differenz der linearen Absorptionskoeffizienten des feuchten und trockenen Holzes gemessen wird. Die Methode benötigt keine Angaben über die Dicke der Probe. Die Dichte wird errechnet aus dem linearen Abschwächungskoeffizienten des Holzes. Eine aufwendige Software einschließlich Bildverarbeitung wurde entwickelt, um die Meßergebnisse auszuwerten.

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Authors and Affiliations

  1. Department of Applied Physics, University of Kuopio, P.O. Box 1627, 70211, Kuopio, Finland

    M. Tiitta & H. Olkkonen

  2. Forest Products Laboratory, Technical Research Centre of Finland, P.O. Box 207, 02150, Espoo, Finland

    T. Lappalainen & T. Kanko

Authors
  1. M. Tiitta
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  2. H. Olkkonen
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  3. T. Lappalainen
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  4. T. Kanko
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Tiitta, M., Olkkonen, H., Lappalainen, T. et al. Automated low energy photon absorption equipment for measuring internal moisture and density distributions of wood samples. Holz als Roh-und Werkstoff 51, 417–421 (1993). https://doi.org/10.1007/BF02628240

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  • DOI: https://doi.org/10.1007/BF02628240

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