The naturally grown material wood exhibits, in addition to its orthotropic material structure, several types of inhomogeneities, where most of them can be allocated to knots and the resulting local fiber deviations. Since they generally lead to a reduction in strength properties, wooden boards must be subjected to a grading process before they can be used as load-bearing elements. Within this process so-called indicating properties are recorded and used to assess the wooden board strength. Common indicating properties are almost exclusively based on surface information of wooden boards while the 3D position and orientation of knots within a board is hardly considered. Thus, algorithms for the 3D reconstruction of wooden boards based on already available surface scans, laser scanning, X-ray or computer tomography data are assessed first within this work. This new knot information allows then the development of novel indicating properties, which consider the knots, the resulting fiber deviation regions and, for bending conditions, the knot location information using height-dependent weighting functions. The statistical evaluation of combinations of the new indicating properties, separately for tensile and bending load conditions, shows that the correlations to experimentally obtained strength properties could be improved significantly with such an approach
The transition metal dichalcogenides are about 60 in number. Two-thirds of these assume layer structures. Crystals of such materials can be cleaved down to less than 1000 Å and are then transparent in the region of direct band-to-band transitions. The transmission spectra of the family have been correlated group by group with the wide range of electrical and structural data available to yield useful working band models that are in accord with a molecular orbital approach. Several special topics have arisen; these include exciton screening, d-band formation, and the metal/insulator transition; also magnetism and superconductivity in such compounds. High pressure work seems to offer the possibility for testing the recent theory of excitonic insulators.
In 2014, this journal published the paper “Characterization of hygrothermal properties of wood-based products – Impact of moisture content and temperature”, presenting among others the vapour permeability of wood-fibre insulation. This discussion demonstrates that the measurement, the calculation and the presentation of this vapour permeability has suffered from various errors, invalidating the obtained intrinsic vapour permeabilities of wood-fibre insulation. This discussion moreover demonstrates that several subsequent authors have furthermore misinterpreted their air-gap-corrected vapour permeabilities as intrinsic vapour permeabilities, which in turn invalidates, at least in part, these authors’ challenges to the state-of-the-art on the measurement and simulation of hygroscopic moisture transport in porous material.