This paper presents a framework for procedural generation of synthetic Norway spruce boards with realistic surface appearance and known internal structure. The framework is intended to support the development of data-driven methods for wood assessment tasks where real paired data are difficult to obtain. The proposed framework combines a data-driven knot sequence generator, a growth-layer model, a fiber-orientation model, and a conditional diffusion model for realistic surface-image generation. Knot sequences are generated using an LSTM model trained on knots extracted from X-ray CT scans of Norway spruce logs. Growth layers are generated using a stochastic model and are modified to account for taper, crook, and knot-induced distortions. A fiber-orientation model is then used to assign 3D fiber directions based on the generated knot and growth-layer geometry. Finally, a modified Stable Diffusion XL model translates the generated surface ring patterns and fiber-orientation maps into realistic RGB images of the board faces. The study also presents a preliminary application of this framework, in which synthetic boards were used to train a model for predicting the cross-sectional ring pattern of a timber board from images of its four longitudinal surfaces. The board generator is made openly available at https://github.com/osamaoa/board_generator.

This study investigated the influence of wane on the tensile strength of structural finger joints in Norway spruce (Picea abies) sideboards intended for use in cross-laminated timber (CLT). The aim was to evaluate whether modifications to current wane limitations in CLT standards could enable increased material utilisation while ensuring acceptable structural performance. A total of 286 finger joints were evaluated. The joints were manufactured using one-component polyurethane adhesive and categorised based on the extent of wane: no wane (NW), allowed wane (AW), and large wane (LW). Board properties, including density and dynamic modulus of elasticity, were determined. Tensile strength was calculated based on both nominal and actual cross-sectional area, and failure modes were documented. Mean strength values for LW joints were similar to those of NW and AW joints, and the reduction in strength was primarily proportional to the missing cross-sectional area. The results show that wane has a limited effect on tensile strength. These findings suggest that increased tolerance to wane may be feasible, particularly in the inner layers of CLT, where tensile stresses are low.

To increase and optimize the use of wood in structural elements, a deep understanding of its mechanical behavior is necessary. The transverse material properties of wood are particularly important for mass timber construction and for utilizing wood as a strengthening material in timber connections. This study experimentally determined the stiffness and strength of Scots pine wood under compression perpendicular to the grain and rolling shear loading, as well as their dependence on the annual ring structure. A previously established biaxial test configuration was employed for this purpose. The modulus of elasticity in the radial direction was found to be about twice that in the tangential direction (687 vs. 372 N/mm2), although the strength in the tangential direction (5.19 N/mm2) was comparatively higher than that in the radial direction (4.70 N/mm2). For rolling shear, especially for the rolling shear modulus, a large variation was found, and its relationship with annual ring structure was assessed. The obtained RS modulus ranged from 50 to 254 N/mm2, while RS strength was found to be between 2.14 and 4.61 N/mm2. The results aligned well with previous findings.

Presence of knots and associated fiber deviation are crucial for engineering properties of sawn timber. Yet, there is a notable absence of a thoroughly calibrated and verified mathematical model for fiber directions. This gap is largely due to the lack of comprehensive and detailed experimental data on growth surface geometry and 3D fiber orientation. Such data, ideally extracted at the sawn timber level, should include diverse information related to single knots, multiple knots, knot clusters, and both live and dead knots. This study presents a comprehensive laboratory examination of a full-size Norway spruce timber board. The extraction of knots, growth surfaces, and full-volume 3D fiber directions was successfully achieved, yielding highly detailed experimental data. The method developed comprises X-ray computed tomography for 3D knot and growth surface geometry, and optical scanning utilizing the tracheid effect for in-plane fiber directions. A limitation was identified when the normal vector of growth surfaces and the normal vector of the optically scanned board surface are orthogonal but a sensitivity analysis revealed that an angle error introduced to the in-plane fiber directions has limited impact on the computed 3D fiber vectors when the angle between the two normal vectors is below 60 degrees. The 3D knot, growth surface geometries, and fiber patterns observed in this study clearly align with the patterns revealed by a previous micro-CT study. The method and data obtained are valuable for the subsequent development of a more refined and rigorously calibrated fiber angle model than those currently available.

Distance to the pith is a parameter that is known to be correlated with the mechanical properties of wood, but it is not utilized in strength grading machines. This study aimed to investigate how different the mechanical properties and grading yields are for Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) boards with small and large distances to the pith, respectively, and whether the distance to the pith could be an interesting parameter to use for strength grading in combination with other predictor variables. For this purpose, 221 boards were scanned to obtain fiber orientation and local density. Their dynamic modulus of elasticity and distance to the pith were measured, and they were finally tested in bending. The boards were classified into two categories: corewood if a board’s cross-section was entirely located within a radius of 200 mm from the pith, and outerwood otherwise. The results show that corewood presents lower mechanical properties than outerwood, explained especially by the higher knottiness of corewood. Distance to the pith improves the grading yields of a machine based on fiber orientation measurements, but using the dynamic modulus of elasticity rather than the distance to the pith leads to better results. Distance to the pith can be used as a single or secondary parameter to predict timber strength if the dynamic modulus of elasticity is not used.

The strength of cross laminated timber (CLT) depends on the stiffness and strength of the lamellas and on the strength of the finger joints. A model for how stiffness and strength vary along and between lamellas is used in combination with a finite element model of CLT and Monte Carlo simulations to calculate out-of-plane bending strength of homogeneous and inhomogeneous CLT. Calculated and experimentally obtained results of characteristic bending strengths, coefficient of variation of bending strength and the proportion of finger joint failures, agree very well for both types of CLT. The characteristic out-of-plane bending strength and the mean bending stiffness were 23% and 16% higher, respectively, for inhomogeneous CLT with outer layer lamellas graded in the strength class C35, compared to homogeneous CLT with all lamellas graded in the class C24. Simulation results give basis for simple equations by which bending strength of CLT can be determined as function of the layup, the strength class of outer layer lamellas and characteristic strength of the finger joints. Furthermore, system effects are investigated. For inhomogeneous CLT, with outer layer lamellas of high strength class, the system effects turn out to be quite different from those of ordinary, homogeneous CLT.

The mechanical properties of structural timber largely depend on the occurrence of knots and on fibre deviation in their vicinities. In recent strength grading machines, lasers and cameras are used to detect surface characteristics such as the size and position of knots and local fibre orientation. Since laser dot scanning only gives reliable information about the fibre orientation in the plane of board surfaces, simple assumptions are usually made to define the inner fibre orientation to model timber boards. Those models would be improved by better insight into real fibre deviation around knots. In the present work, a laboratory method is developed to evaluate growth layers geometries and fibre orientation, solely based on the fact that the fibers are parallel to the tree rings and without any further assumptions. The method simply relies on color scans and laser dot scans of Douglas fir (Pseudotsuga menziesii) timber specimen sections revealed by successive planing. The proposed method provides data on fibre orientation in 3D with an accuracy that is relevant for the calibration of detailed models.

Cross-Laminated Timber (CLT) is an engineered wood product composed of solid layers of glued sawn timber. In this study, essential material stiffness parameters for CLT made from Norway spruce and Scots pine are evaluated. Specifically, the longitudinal modulus of elasticity (MoE) for longitudinally oriented layers and the effective rolling shear modulus for transversely oriented layers are the focus. By combining finite element (FE) analysis with four-point, out-of-plane bending tests using digital image correlation (DIC), a robust assessment of the effective rolling shear modulus of CLT layers is achieved. Additionally, eigenvalue analysis, applied to an FE model, along with resonance frequencies obtained from dynamic excitation of CLT, enables stable and simultaneous assessment of the dynamic longitudinal MoE and effective rolling shear modulus. Notably, while the dynamic MoE of longitudinal CLT layers is only 4% higher than the quasi-static local MoE, the dynamic effective rolling shear modulus of CLT layers is 40% higher than the quasi-static effective rolling shear modulus. This finding indicates a tangible viscoelastic behavior of wood concerning rolling shear.

This paper proposes a one-dimensional convolutional long short-term memory (1D-CNN-LSTM) model for estimating the pith position and average ring width in Norway spruce timber boards. The model predicts these crosssectional parameters by processing sequences of light-intensity signals derived from optical scans of the board's four surfaces. The dataset used for training the model consists of synthetic boards sawn from simulated 3D logs. The model was evaluated on a dataset consisting of 552 end cross-sections from actual Norway spruce boards. Comparisons between the automatic and manual pith and ring width estimations demonstrated a very good accuracy. The computational speed of the model was more than twice as fast as the quickest method available in the literature. A large set of boards was then used to determine the advantages of incorporating the automatically determined average ring width in formulating indicating properties for machine strength grading. This evaluation revealed that the average ring width could, in certain situations, compensate for unknown variables such as density or resonance frequency in predicting the tensile and bending strength of Norway spruce boards.

PDF fiel - 55K, Provides source for all reagents used in this study

The use of cross laminated timber (CLT) for construction has increased greatly in recent years and the large volumes of wood used for CLT means that it is important to optimize the use of the material. This requires relevant grading of lamellas and knowledge of relationships between lamella and CLT properties. In the present study, the relationship between dynamic axial modulus of elasticity (MoE) of lamellas and the quasi-static out of plane bending stiffness of CLT is investigated. By means of four-point bending test, it is shown that the effective quasi-static MoE of lamellas in CLT is only 2–6% lower than the average axial dynamic MoE of the individual lamellas. With this knowledge, producers of CLT can easily predict and control the important out of plane bending stiffness of the produced CLT. Moreover, it is shown that effective rolling shear stiffness of layers in CLT can be accurately determined by means of digital image correlation performed in connection to four-point bending of CLT, even for long test spans. For layers of lamellas of Scots pine of size 40 × 190 mm 2 the average apparent or effective rolling shear modulus was determined to be 159 MPa. The average rolling shear modulus of the same material was determined to be 56 MPa.

PDF file - 1.2MB, Supplemental Figure 1. TasQ does not inhibit total HDAC enzymatic activity in HUVEC, LNCaP, or CWR22-Rv1 cells. Supplemental Figure 2. A. HDAC4 m-RNA expression in normal vs. metastatic prostate cancer tissues. B.Cytoplasmic vs. nuclear expression of HDAC4, beta-actin, and H3-histone protein in normal (i.e., PrEC) vs. prostate cancer cell lines. Supplemental Figure 3. A. Recombinant human HDAC4 in which the C669 and H675 in the ZRD are mutated to alanine preventing formation of the active conformation retains high affinity binding for TasQ as determined by surface plasmon resonance. B. A series of specific and non-specific HDAC4 shRNA lentiviral constructs were tested for their ability to down regulate HDAC4 in LNCaP cells. C. HDAC4 shRNA2 knock-down LNCaP cells are also non-tumorigenic in mice. D. Histology 56 days post inoculation of HDAC4 shRNA2 knock-down LNCaP cells. E. Histology 56 days post inoculation of shRNA2 knock down LNCaP cells which have had restoration of HDAC4 expression (i.e., arrows denote mitotic cells). Supplemental figure 4. TasQ inhibits the LDH-A protein expression under both normoxic and hypoxic conditions. B. TasQ inhibits HIF-1 dependent transcription induced by hypoxia

Optical scanning and X-ray computed tomography (CT) scanning of sawn timber provide a large number of data points, on which data-driven numerical models can be based for simulations.These models require information about the deviations of the fibre orientations in the vicinity of knots.Optical scanning can be used to measure the in-plane fibre orientation on wood surfaces.In CT scans of sawn timber, the fibre orientation around knots can be estimated using a new fibre reconstruction algorithm based on the density gradient.The goal of this paper is to compare and synchronise optical and CT scanning data of sawn timber and then use the combined data set to evaluate fibre orientations derived from both representations.The material comprised sawn timber of Norway spruce, in which alignment holes were drilled.The timber was scanned in an industrial CT scanner and subsequently in an industrial optical scanner where scanning was repeated after successive planing of the sawn timber surface.The results show that a projective mapping in combination with a spline interpolation are required for synchronisation, and that the in-plane fibre orientations calculated from the density gradients are qualitatively similar to the orientations derived from the optical data.

In softwood species, annual ring width correlates with various timber characteristics, including the density and modulus of elasticity along with bending and tensile strengths. Knowledge of annual ring profiles may contribute to more accurate machine strength grading of sawn timber. This paper proposes a fast and accurate method for automatic estimation of ring profiles along timber boards on the basis of optical scanning. The method utilizes two 1D convolutional neural networks to determine the pith location and detect the surface annual rings at multiple cross-sections along the scanned board. The automatically extracted rings and pith information can then be used to estimate the annual ring profile at each cross-section. The proposed method was validated on a large number of board cross-sections for which the pith locations and radial ring width profiles had been determined manually. The paper also investigates the potential of using the automatically estimated average ring width as an indicating property in machine strength grading of sawn timber. The results indicated that combining the automatically estimated ring width with other prediction variables can improve the accuracy of bending and tensile strength predictions, especially when the grading is based only on information extracted from optical and laser scanning data.(C) 2022 The Author(s). Published by Elsevier Ltd.

The connection between branch and trunk in a tree must be strong enough to transfer all loads acting on the branch, and it is well known that such branch-stem connections are indeed very strong. In this paper, X-ray computer tomography is employed to investigate the local fibre orientation in the close surrounding of a knot in a Norway spruce specimen to better understand the origins of the mechanical strength of the branch-trunk connection. First, a wood specimen containing an entire knot from pith to bark was imaged with a voxel size of 52 µm. Subsequently, smaller specimens were cut from this original specimen and imaged again with increasingly higher resolution over four levels. With the highest resolution level (2.6 µm voxel size), the tracheids with smallest lumen were successfully traced. The results revealed how the direction of the fibre paths that start below the knot curve around it as the paths progress upwards to the region just above the knot, where the paths divide into two: one set of paths integrating with the knot on its top side and the other set continuing up along the trunk. Fibres that integrate with the knot at its top follow paths just before they continue into the knot, with a radius of curvature of only about 1 mm in both vertical and horizontal directions. No abrupt change of fibre pattern between latewood and earlywood is observed; rather, a continuous change of fibre direction across annual layers can be seen. The detailed characterisation of the local fibre structure around the knot provides new data that can explain the remarkable strength of the branch-trunk connection.

Efficient utilization of structural timber requires accurate methods for machine strength grading. One of the most accurate methods presented this far is based on data of local fiber orientation on board surfaces, obtained from laser scanning. In this paper, two potential improvements of this method are examined. The first one consists of replacing a model based on simple integration over cross sections of boards for calculation of local bending stiffness by a 3D solid finite element (FE) model from which local bending stiffness is derived. The second improvement concerns replacement of a simple model for the fiber orientation in the interior of board by a more advanced one taking location of pith and growth direction of knots into account. Application of the alternative models on a sample of more than 200 Douglas fir boards, size 40 mm X 100 mm X 3000 mm, cut from large logs, show that each of the evaluated model improvements contributes to improved grading accuracy. When local bending stiffness is calculated utilizing the herein suggested FE model in combination with the improved model of fiber orientation in the interior of boards, a coefficient of determination to bending strength as high as 0.76 is obtained. For comparison, a coefficient of determination of 0.71 is obtain using the simpler original models.

In sawn timber, the presence of defects, mainly knots, cause the fibres to deviate from the longitudinal direction of the board and thereby lead to a significant reduction of strength and stiffness. Hence, the aim of the present research was to develop a method and algorithm to mathematically represent the orientation of fibres at any point on a 3D growth surface in the surroundings of knots and within geometrically reconstructed timber boards. The entire procedure consisted of three automatic steps, namely 1) detection of knots on board surfaces, 2) modelling and reconstruction of knots in 3D and 3) application of a novel model for fibre orientation in the surroundings of knots. The curved geometry of knots was taken into account, and the fibre orientation, at any point within the board, was calculated solely as a function of the shape of the growth surface at that point. The proposed function for fibre orientation enabled a physically feasible definition of fibre deviation zone, which was related to the geometry of the modelled growth surface, i.e. the knot bump caused by the occurrence of a knot. Validation of the proposed method for modelling of 3D fibre direction in timber boards was performed using a total sample of 100 boards of Norway spruce. The results presented show a very good agreement between model-obtained and experimentally-obtained in-plane fibre directions.