Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2008
Sammendrag
No abstract has been registered
Forfattere
Toril Eklo Trond HofsvangSammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Forfattere
Erik LarnøySammendrag
To evaluate the decay resistance of wood, treated or untreated, for hazard classes 3, 4 and 5, the mass loss due to fungal exposure needs to be calculated. The standards for calculating mass loss in wooden test samples (i.e EN 113 and ENV 807) require that the samples used in the test are pre-dried to 0 % moisture content, m0, for determination of the initial dry mass. The standards describe that the samples should be dried at 103±2°C for 18 hours. When drying wood samples to 103 °C the samples are altered. Literature describes that extractives are influenced at temperatures as low as 60 °C, and redistribution and/or evaporation of these, will change the characteristics of the wood samples...
Sammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Forfattere
Peder GjerdrumSammendrag
Moisture content, volatile in nature, is an important trait for any timber customer. Commercial board samples were observed to yield formulas for EMC reduction by kiln temperature, for hysteresis by board length, and for MC sorption dynamics by temperature. Industrial kiln practice lowers the EMC to approximately 95% of tabulated values. In this work, hysteresis was verified, and the most significant impact in natural ambient is that moisture migration to the board center appears to catch up with surface adsorption, reducing the influence of temperature and surface resistance. A concluding procedure for estimating MC dynamics for timber boards on stickers is outlined.
Forfattere
Peder Gjerdrum Olav Albert HøibøSammendrag
A huge effort has been put into modelling wood quality the last few decades. Predicting knot size has been the centre of interest, either for timber quality, for tree growth models, or related purposes. The main objective of this paper is to analyse the stochastic features connected to knot distribution inside the three-dimensional volume of a tree\"s trunk. Four large Alpine spruce trees were sampled; age 150 years, DBH 30 to 70 cm, total volume 14.5 m3. To open a possibly large part of the stems, they were cross-cut to 31 logs and sawn to 193 unedged boards. On each unique board surface all perceptible knots were observed and localised in polar coordinates; origin in the stem base, along the pith and in the north direction. A total of 6200 knot intersections were observed in the 283 m2 sawn surfaces; however, most knots were observed several times in consecutive sawn surfaces. In order to obtain stationary variable, knot size was transformed by dividing by the square root of radial distance, and radial distance was transformed by dividing by log radius at the given location. Relative size, knot quality and spatial distribution were largely random and not correlated to each other in a tree. Thus, knots demonstrate a double nature, one part obeying the physiological laws, and another part stochastic.