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When a radial strip is cut from an increment core it can potentially be cut with two orientations: parallel to longitudinal tracheids, i.e., a radial-longitudinal (RL) strip (the orientation of SilviScan samples), or at an orientation of 908 to the tracheids, i.e., a radial-transverse (RT) strip. Both strips could be used for near-infrared (NIR) analysis, but it is unknown how calibrations based on RT-face NIR spectra compare with those based on RL-face NIR spectra. A total of 20 Pinus taeda L. (loblolly pine) RL strips were characterized in terms of air-dry density, microfibril angle (MFA), stiffness and several tracheid morphological characteristics. NIR spectra were collected in 10-mm increments from the RL and RT faces of matching strips and used to develop calibrations for each property. In general, RL-face NIR spectra gave calibrations that provided stronger relationships. Differences between the two sets of calibrations were small, indicating that either face could be used for NIR analysis.

A range of important wood properties can be predicted using calibrations obtained using SilviScan data and diffuse reflectance near infrared (NIR) spectra collected from wooden strips cut from increment cores. The ease of NIR measurements and the rapid provision of SilviScan data provides the opportunity to establish extremely large data sets, causing calibration problems. An option is to reduce the number of data points representing an individual NIR spectrum. NIR spectra were collected in 10 mm increments from the radial longitudinal face of 89 Pinus taeda L. (loblolly pine) breast height (1.30 m) wooden strips using a Foss NIRSystems 5000 [wavelength range 1100-2498 nm, spectral sampling interval (SSI) 2 nm]. Air-dry density, microfibril angle (MFA) and stiffness calibrations were obtained using SSIs ranging from 2 to 64 nm. Calibrations developed using NIR spectra having SSIs of 4 or 8 nm performed as well as those obtained at 2 nm. As resolution was decreased (SSI increased), the quality of the calibrations associated with the various wood properties was affected to different degrees. The MFA calibration was the most affected and air-dry density the least.

Abstract. This paper contains a report on a selection of recent research projects carried out at the Institute for Mechanics of Materials and Structures of Vienna University of Technology. The aim of this report is to demonstrate that Computational Mechanics of Materials and Structures is a scientific field with many characteristics of an electronic golem.