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Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber II: evaluation of models generated on a pixel level
Luleå tekniska universitet. Luleå.
2006 (English)In: Journal of Wood Science, Vol. 52, 39-43 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2006. Vol. 52, 39-43 p.
URN: urn:nbn:se:umu:diva-46081OAI: diva2:436946
Available from: 2011-08-25 Created: 2011-08-25 Last updated: 2011-09-07
In thesis
1. Microwave sensors for scanning of sawn timber
Open this publication in new window or tab >>Microwave sensors for scanning of sawn timber
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A microwave imaging sensor that measures the signal transmitted through a board was investigated with respect to the ability to predict the distribution of moisture and density in sawn lumber. Furthermore, the response from the sensor was related to strength properties of the boards. Multivariate statistics was used to relate the measured variables to various properties. A finite element model based on X-ray computed tomography images was developed to describe the interactions between microwaves and wood. The model made it possible to simulate the response from the sensor under varying conditions.

The results show that microwaves can be used for prediction of density and moisture content. They can also be used for prediction of strength properties, mainly from the correlation to density, but also from the influence on microwaves of structural variations in the wood. The finite element model is useful in the evaluation of microwave sensors for wood, drying equipment or other applications where electromagnetic waves interact with wood.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2007. 40 p.
, Doctoral thesis / Luleå University of Technology, 2007:9
microwave scanning; wood; density; moisture content; strength grading; finite element
National Category
Control Engineering
urn:nbn:se:umu:diva-46102 (URN)1402-1544 (ISBN)
Public defence
2007-04-18, Hörsal A, Forskargatan 1, Skellefteå, 10:00 (English)
Available from: 2011-08-29 Created: 2011-08-26 Last updated: 2011-08-29Bibliographically approved

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