Abstract
The purpose of this study was to use images from a microwave sensor on a pixel level for simultaneous prediction of moisture content and density of wood. The microwave sensor functions as a line-scan camera with a pixel size of 8mm. Boards of Scots pine (Pinus sylvestris), 25 and 50mm thick, were scanned at three different moisture contents. Dry density and moisture content for each pixel were calculated from measurements with a computed tomography scanner. It was possible to create models for prediction of density on a pixel level. Models for prediction of moisture content had to be based on average values over homogeneous regions. Accuracy will be improved if it is possible to make a classification of knots, heartwood, sapwood, etc., and calibrate different models for different types of wood. The limitations of the sensor used are high noise in amplitude measurements and the restriction to one period for phase measurements.
Article PDF
Similar content being viewed by others
References
Kraszewski A (1980) Microwave aquametry — a review. J Microwave Power 15:209–220
Zhang Y, Okamura S (1999) New density-independent moisture measurement using microwave phase shifts at two frequencies. IEEE Trans Instru Measurement 48:1208–1211
Bolomey JC, Cottard G, Lhiaubet GC, Ciccitelli J, Portala JF (1992) On-line control in wood and paper industries by means of rapid microwave linear sensor. Proceedings of 22nd European Microwave Conference, Espoo, 24–27 Aug 1992, Topic 16
Choffel D, Goy B, Martin P, Gapp D (1992) Interaction between wood and microwaves — automatic grading application. In: Lindgren O (ed) 1st International Seminar on Scanning Technology and Image Processing on Wood. Luleå University, Skellefteå, Sweden, pp 1–8
Johansson J, Hagman O, Fjellner B-A (2003) Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber. J Wood Sci 49:312–316
Von Hippel A (1954) Dielectrics and waves. Wiley, New York
King RJ (1978) Microwave electromagnetic nondestructive testing of wood. Proceedings of 4th Symposium on Nondestructive Testing of Wood. Washington State University, Pullman, pp 121–134
Torgovnikov GI (1993) Dielectric properties of wood and wood-based materials. Springer, Berlin Heidelberg New York
Lindgren LO (1991) Medical CAT-scanning: X-ray absorbtion coefficients, CT-numbers and their relation to wood density. Wood Sci Technol 25:341–349
Johansson J (2001) Property predictions of wood using microwaves. Licentiate Thesis, Luleå University of Technology, LIC 2001:35
Bolomey JC, Gardiol FE (2001) Engineering applications of the modulated scatterer technique. Artech House
Martens H, Næs T (1989) Multivariate calibration. Wiley, New York, pp 22–163
Author information
Authors and Affiliations
Corresponding author
About this article
Cite this article
Lundgren, N., Hagman, O. & Johansson, J. Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber II: evaluation of models generated on a pixel level. J Wood Sci 52, 39–43 (2006). https://doi.org/10.1007/s10086-005-0724-9
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s10086-005-0724-9