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Predicting the strength of Norway spruce by microwave scanning: A comparison with other scanning techniques
Luleå tekniska universitet, Luleå.
2007 (English)In: Wood and Fiber Science, Vol. 39, 167-172 p.Article in journal (Refereed) Published
Abstract [en]

In this study, 90 boards of Norway spruce (Picea abies (L.) Karst.) sized 48 x 148 mm in cross-section, have been examined using different scanning and measurement techniques. All of the boards originated from a sawmill located in southern Finland. Planar X-ray scanning, microwave scanning, and grain-angle measurement have been performed. In addition, strength and elastic properties were assessed for each piece by four point bending. The purpose of the study was to relate the potential of microwave scanning compared to other, industrially available techniques and to explain the physiological background of the microwave responses. The results show that the microwave signal, after transmission through wood, contains information about the bending strength and the modulus of elasticity. The correlation to density is a key factor. Annual ring width was also found to be correlated both to microwave measurements and strength properties.

Place, publisher, year, edition, pages
2007. Vol. 39, 167-172 p.
Identifiers
URN: urn:nbn:se:umu:diva-46080OAI: oai:DiVA.org:umu-46080DiVA: diva2:436952
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.
Series
Doctoral thesis / Luleå University of Technology, 2007:9
Keyword
microwave scanning; wood; density; moisture content; strength grading; finite element
National Category
Control Engineering
Identifiers
urn:nbn:se:umu:diva-46102 (URN)1402-1544 (ISBN)
Public defence
2007-04-18, Hörsal A, Forskargatan 1, Skellefteå, 10:00 (English)
Opponent
Supervisors
Available from: 2011-08-29 Created: 2011-08-26 Last updated: 2011-08-29Bibliographically approved

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Lundgren, Nils

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