Moisture Content Measurement in Scots Pine by Microwave and X-Rays
Keywords:Wood, inline, attenuation, phase shift, knots
AbstractThere is demand in the Swedish sawmill industry to improve the accuracy of moisture content measurements, both to obtain a better tool to run production and to ensure that the products meet customer expectations. In this study, 240 well-conditioned pieces of Scots pine (Pinus sylvestris), sorted into five different groups by visual inspection, were measured using microwaves and X-rays. Models to predict moisture content of wood were made by measurements of an additional 45 pieces of wood. Using only measured quantities from the microwave system, ie attenuation and phase shift, the root mean square error (RMSE) of the estimated moisture content was 1.00%. By adding total density from the X-ray measurements, RMSE of the estimated moisture content was lowered to 0.89%. Mean errors of the different wood groups varied from -0.65 to 0.18%.
CEN (2002) EN 13183-1. Moisture content of a piece of sawn timber. Part 1: Determination by oven dry method. European Committee for Standardization, Brussels, Belgium.nDanvind J (2002) PLS prediction as a tool for modeling wood properties. Holz Roh Werkst 60(2):130-140.nDinwoodie JM (2000) Timber: Its nature and behavior. Spon Press, London, UK.nEriksson L, Johansson E, Kettaneh-Wold N, Trygg J, Wikström C, Wold S (2006) Multi and megavariate data analysis. Umetrics AB, Umeå, Sweden.nEsping B (2003) Test av kommersiella fuktkvotsmätare in-line. Trätek rapport Trätek, Stockholm, Sweden [in Swedish].nEsping B, Salin J-G, Brander P (2005) Fukt i trä för byggindustrin. Trätek, Stockholm, Sweden [in Swedish].nHansson L, Lundgren N, Antti L, Hagman O (2005) Microwave penetration in wood using imaging sensor. Measurement 38(1):15-20.nJohansson J (2001) Property predictions of wood using microwaves. Licentiate, Luleå University of Technology, Skellefteå, Sweden.nLindgren O (1992) Medical CT-scanners for non-destructive wood density and moisture content measurements. Doctoral, Luleå University of Technology, Luleå, Sweden.nLundgren N, Hansson L (2007) PLS models for predicting wood properties from microwave measurements based on three dimensional FEM simulations. Proceedings, Nordic workshop on wood engineering, Luleå University of Technology, Skellefteå, Sweden.nMontgomery DC, Runger GC, Hubele NF (2004) Engineering statistics. John Wiley & Sons, Hoboken, NJ.nNilsson M (2010) Evaluation of three in-line wood moisture content meters. MS thesis, Luleå University of Technology, Skellefteå, Sweden.nSchajer G, Orhan F (2005) Microwave non-destructive testing of wood and similar orthotropic materials. Sensing and Imaging: An International Journal 6(4): 293-313.nSchajer GS, Orhan FB (2006) Measurement of wood grain angle, moisture content and density using microwaves. Holz Roh Werkst 64(6):483-490.nSchlemm U (2004) Mass and moisture measurement by use of the microwave resonator technique. Technical bulletin, Tews Elektronik, Hamburg, Germany.nVikberg T (2010) Fuktkvotsmätare för träindustrin: En kartläggning av metoder för mätning av fuktkvoter i intervallet 7-18 fuktkvotsprocent. Technical report, Luleå University of Technology, Skellefteå, Sweden [in Swedish].n
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.