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.
2003
Authors
Holger LangeAbstract
High resolution digital elevation maps (DEMs) offer the investigation of multifractal properties of the spatial characteristics of river basins like the width function, and the determination of the relation between average slope and basin area.There have been a number of universality claims in this respect; the range of the scaling exponent for the slope-area relation seems to be narrow, and the multifractal spectrum of the width function is characterized by a single site-specific Lipschitz-Hlder exponent alpha, the spectrum having an envelope given by that of Peanos basin.Comparing 17 river basins covering two orders of magnitude in basin area, our findings do not confirm this universal character. In particular, the Lipschitz-Hlder exponent crucially depends on the resolution of the width function extraction; we show that it is easy to produce almost identical spectra for completely different basins when varying the resolution.The problem of interior points is also encountered. We adopt Venezianos modified calculation of f(alpha) in this case. The slope-area exponent covers a wide range of values which also include the pure random case. We thus question the usability of these measures as a classification tool for river basins. http://www.cosis.net/abstracts/EAE03/05246/EAE03-J-05246.pdf
Authors
Bjørn ØklandAbstract
No abstract has been registered
Authors
Ali Temiz Morten Eikenes U.C. Yildiz Fred G. Evans Bjørn JacobsenAbstract
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Authors
Roger A. SedjoAbstract
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Authors
Peder GjerdrumAbstract
Artikkelen omhandler forsøksopplegg og reslultater av forsøk med 1) små feilfri prøver tørket ved temperaturer 30 - 60 - 90 - 120 grader og 2) prøver av varierende lengde/kvalitet av vanlig, industrielt fremstilt trelast av gran. For trelast tørket ved temperatur opp til 60-75 grader er det liten endring av likevektsfuktigheten (LVF) og i hysterese, med økende effekt for høyere tørketemperatur. LVF ble funnet å øke proporsjonalt med logaritmen av prøvens lengde, og slik at prøver med kvist mv. har 0.4 %-enh. lavere LVF enn feilfri prøver av samme lengde. Også hysteresis øket med økende lengde. Ettersom bare en begrenset del av området for faktorer som påvirker LVF og hysterese er undersøkt, bør undersøkelsene fortsette.
Authors
Per Otto Flæte Erlend Ystrøm HaartveitAbstract
For manufacturing of naturally durable products of Scots pine it is crucial to separate heartwood from the non-durable sapwood. The objectives of this study were to evaluate near infrared (NIR) spectroscopy as a non-destructive method for classifying heartwood and sapwood in Scots pine sawn wood, and to evaluate the applicability of NIR-spectroscopy in predictions of heartwood resistance to decay. Wood durability is measured by mass loss from fungal activity in a laboratory experiment.Using NIR-spectra in fully cross-validated partial least squares (PLS1) regression models, results show that it is possible to correctly classify samples of heartwood and sapwood. The results further demonstrate that resistance to decay in Scots pine heartwood and sapwood can be modelled with satisfying precision using NIR-spectroscopy. Within-tree variation in heartwood resistance to decay show the importance of building reliable models for identification of highly decay resistant heartwood, to accomplish a purposeful utilisation of naturally durable heartwood.
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Authors
Inge Stupak Møller Staffan JacobsonAbstract
No abstract has been registered