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  • 1.
    Nilsson, Daniel
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Nilsson, Bengt
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Bergh, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Amount of nutrients extracted and left behind at a clear-felled area using the fresh-stacked and dried-stacked methods of logging residue extraction2018Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 33, nr 5, s. 437-445Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nutrient removal has been one of the key issues since the harvesting of logging residues started in Sweden. This study examined the actual removal of nutrients by measuring the amounts of biomass removed (from a forest products perspective) combined with their respective nutrient concentrations (N, P, Ca, K and Mg), from a clear-felled area when using the dried-stacked and fresh-stacked methods. The most important finding is that the two methods were very similar regarding nutrients remaining at the clear-felled area. Of the nutrients remaining there, most were found to be well distributed between the harvester heaps. Both methods fulfilled the requirements of the Swedish Forest Agency. A sensitivity analysis showed that even if the dried-stacked method left more needles, or the fresh-stacked method extracted more logging residues, there would only be a small impact on the levels of nutrients removed. The sensitivity analysis also showed that the amount of logging residues remaining between the harvester heaps seems to be much more important for nutrients left behind, regardless of extraction method. With this in mind, it is highly probable that improvements to the extraction of logging residues, without increasing nutrient removal, can be made.

  • 2.
    Lundmark, Tomas
    et al.
    Swedish University of Agricultural Sciences.
    Poudel, Bishnu Chandra
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Gustav, Stål
    Swedish University of Agricultural Sciences.
    Nordin, Annika
    Swedish University of Agricultural Sciences.
    Sonesson, Johan
    Skogforsk.
    Carbon balance in production forestry in relation to rotation length2018Ingår i: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Canadian Journal of Forest Research, ISSN 0045-5067, Vol. 48, nr 6, s. 672-678Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The choice of a rotation length is an integral part of even-aged forest management regimes. In this study, we have simulated stand development and carbon pools in four even-aged stands representing the two most common tree species in Fennoscandia, Norway spruce (Picea abies) and Scots pine (Pinus sylvestris), growing on high and low productive sites. We hypothesized that increased rotation lengths (+10, +20 and +30 years) in comparison with today’s practice would increase forests’ average carbon stock during a rotation cycle, but decrease the average yield. The results showed that for spruce a moderate increase in rotation length (+10 years) increased both average standing carbon stock and average yield. For the longer alternatives (+20 and +30 years) for spruce and for all pine alternatives prolonging rotation lengths resulted in increased average standing carbon stocks but decreased average yield resulting in decreased carbon storage in forest products and decreased substitution effects. Decreasing the rotation lengths (-10 years) always resulted in both decreased average standing carbon stocks and decreased yields. We conclude that a moderate increase of rotation lengths may slightly increase forests’ climate benefits for spruce sites but for all other alternatives there was a trade-off between the temporary gain of increasing carbon stocks and the permanent loss in productivity and consequently substitution potential.

  • 3.
    Trischler, Johann
    et al.
    Luleå University of Technology.
    Sandberg, Dick
    Luleå University of Technology.
    Dorn, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Effect of temperature during vital gluten adhesive preparation and application on shear-bond strength2018Ingår i: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 32, nr 4, s. 448-455Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    If protein-based adhesives are to become a competitive bio-based alternative to synthetic adhesives, the preparation and application methods have to be considerable improved to reduce process time and thereby improve the economy of the adhesive system. The purpose of this study was to investigate the impact of the temperature during preparation and application on the shear-bond strength of an adhesive based on vital gluten for use in wood applications. Vital gluten was used in its natural form and mixed with water of different temperatures (preparation temperature 0 °C or 20 °C), and applied on beech veneer at different temperature (application temperature –10, 20, 60 and 100 °C). Tensile shear-bond strength samples were prepared and tested according to EN 205. The results showed that an increase in veneer temperature during application of the adhesive led to a decrease in the shear-bond strength, but that the preparation temperature of the adhesive had no influence on the strength.

    Publikationen är tillgänglig i fulltext från 2018-08-08 23:59
  • 4.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Georg-August-University, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Mai, Carsten
    Georg-August-University, Germany.
    Effects of acid pre-treatments on the swelling and vapor sorption of thermally modified Scots pine (Pinus sylvestris L.) wood2018Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, nr 1, s. 331-345Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scots pine sapwood samples were pre-treated with a Lewis acid (AlCl3) and a combination of Lewis and protonic acids (AlCl3 and H2SO4), and were subsequently exposed to respective temperatures of 180 °C and 120 °C for establishing a comparable mass loss with those impregnated with demineralized water and solely thermally modified at 220 °C. Water impregnated samples dried at 120 °C also served as controls. The swelling behavior of all wood samples was examined with respect to maximum swelling in water, anti-swelling efficiency (ASE), shrinkage, and dynamic water vapor sorption at relative humidity ranges of 0% to 95%. The thermal modification at 220 °C diminished swelling and moisture adsorption, and also reduced moisture increment and decrement compared with the unmodified control. However, it was less obvious than both acid pre-treated samples. Excess surface work and Hailwood-Horrobin results calculated from water vapor sorption studies demonstrated that, at comparable mass loss, the available sorption sites were reduced to a greater extent by Lewis acid and combination of Lewis and protonic acids pre-treatment than the sole thermal treatment. This was attributed to more pronounced degradation of polysaccharides, mainly hemicelluloses and amorphous parts of cellulose, and to cross-linking of cell wall polymers due to the acid pre-treatments.

  • 5.
    Hu, Min
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Briggert, Andreas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Olsson, Anders
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Johansson, Marie
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Oscarsson, Jan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Säll, Harald
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Growth layer and fibre orientation around knots in Norway spruce: a laboratory investigation2018Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, nr 1, s. 7-27Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The strength of structural timber largely depends on the occurrence of knots and on the local material directions in the surroundings of such knots. There is, however, a lack of methods for establishing a full dataset of the local material directions. The present research aims at the development and application of a laboratory method to assess the geometry of growth layers and the orientation of fibres in a high-resolution 3D grid within wood specimens containing knots. The laboratory method was based on optical flatbed scanning and laser scanning, the former resulting in surface images and the latter, utilizing the tracheid effect, resulting in in-plane fibre angles determined in high-resolution grids on scanned surfaces. A rectangular solid wood specimen containing a single knot was cut from a tree in such a way that it could be assumed that a plane of symmetry existed in the specimen. By splitting the specimen through this plane through the centre line of the knot, two new specimens with assumed identical but mirrored properties were achieved. On one of the new specimens, the longitudinal-radial plane was subsequently scanned, and the longitudinal–tangential plane was scanned on the other. Then, by repeatedly planing off material on both specimens followed by scanning of the new surfaces that gradually appeared, 3D coordinate positions along different growth layers and 3D orientation of fibres in a 3D grid were obtained. Comparisons between detected fibre orientation and growth layer geometry were used for the assessment of the accuracy obtained regarding 3D fibre orientation. It was shown that the suggested method is well suited to capture growth layer surfaces and that it provides reliable information on 3D fibre orientation close to knots. Such knowledge is of great importance for understanding the properties of timber including knots. The quantitative data obtained are also useful for calibration of model parameters of general models on fibre orientation close to knots.

  • 6.
    Hultkrantz, Lars
    et al.
    Örebro University.
    Mantalos, Panagiotis
    Hedging with trees: Tail-hedge discounting of long-term forestry returns2018Ingår i: Journal of Forest Economics, ISSN 1104-6899, E-ISSN 1618-1530, Vol. 30, s. 52-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tail-hedge discounting is based on decomposition of returns from long-term investments in a fraction (gamma) that is correlated with consumption and another that is not. The first part is discounted at a discount rate that includes a risk premium, the other with the risk-free rate. We estimate gamma for forestry on Swedish data for stumpage prices and GDP per capita 1909-2012. We demonstrate that the result considerably changes the expected present value of medium-term and long-term forest investments. (C) 2018 Department of Forest Economics, Swedish University of Agricultural Sciences, Umea. Published by Elsevier GmbH. All rights reserved.

  • 7.
    Schweigler, Michael
    Vienna University of Technology.
    Nonlinear modeling of reinforced dowel joints in timber structures: a combined experimental-numerical study2018Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Steel dowels are indispensable elements for the design of joints in modern timber structures. Dowels are broadly used because of their flexibility in design and easy assembling on-site, as well as due to their advantageous mechanical behavior. Recent developments in reinforcement techniques allow for designing ductile dowel joints, which exhibit nonlinear slip behavior. However, currently applied limit state approaches for calculation of connection strength are not able to fully exploit the potential of dowel joints. This calls for development of more advanced calculation methods, which was aimed for in this thesis.

    For thorough understanding of the complex mechanical behavior of dowel connections, application of a so-called multiscale approach is advantageous. Thereby, nonlinear loaddeformation behavior of dowel connections is studied on different length scales, from the scale of connection components, up to the joint level. The aim of this thesis was to exploit knowledge from lower scales in models that finally allow for nonlinear analysis of timber structures. In the work at hand, this was achieved by a combined experimental-numerical analysis.

    Experimental studies on the nonlinear embedment slip of ductile dowel connections, and its relation to the orthotropic material behavior of wood, was one of the objectives of this work. Breaking new ground by testing up to large dowel displacements, at various angles to the grain, for unconstrained and constrained lateral displacement conditions, required development of new testing procedures and test setups. Test results gave access to nonlinear embedment slip curves and showed their dependence on loading direction and lateral displacement conditions.

    In the next step, embedment slip data were exploited in modeling of single-dowel connections. Beam-on-nonlinear foundation modeling was applied for this purpose. Validation of connection tests and a parameter study not only highlighted suitability of the calculation method, but allowed for gaining insight into limit states. Thus, beam-on-foundation modeling was found to be an attractive alternative to advanced 3D FEM models for engineering design.

    Parameterized equations for regression analysis of nonlinear slip curves, and interaction curves describing the grain angle dependence of mechanical parameters, were summarized in a literature review. With these equations at hand, a multi-dimensional parameterization method for the nonlinear slip as a function of the load-to-grain angle was developed. This method was applied to experimental data derived in embedment and single-dowel connection tests as well as in simulations. Analytical equations for connection slip are expected to facilitate engineering modeling at the single-dowel connection and joint level, respectively.

    Joint modeling aimed at establishing a calculation method suitable for engineering design with an attractive trade-off between modeling effort, calculation time and accuracy. This was tackled by a semi-analytical model based on nonlinear elastic springs for the dowel slip and rigid connection members. Thereby, global joint slip, and thus stiffness and strength of joints, as well as local load distribution within joints can be predicted. This model proved to be suitable for single-dowel-based and joint-based design concepts. Calculation examples showed pronounced influence of loading direction dependence and nonlinearity of dowel slip on local load distribution, as well as on global joint slip. Influence of interaction between internal forces on the joint stiffness became obvious from structural analysis with nonlinear joint slip.

    This work covers a combined experimental-numerical analysis of the slip behavior of ductile dowel joints, from the wood embedment and steel dowel bending behavior, the single-dowel slip, to the joint behavior, with final application in nonlinear structural analysis. Presented models predicted nonlinear slip with suitable accuracy and efficiency. Application of nonlinear joint slip in structural analysis showed the potential of ductile dowel joints, which could be exploited in engineering design by the herein presented multiscale modeling strategy.

  • 8.
    Hallingbäck, Henrik
    et al.
    Swedish University of Agricultural Sciences.
    Högberg, Karl-Axel
    The Forestry Research Institute of Sweden.
    Säll, Harald
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Lindeberg, Johan
    Johansson, Marie
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Gunnar, Jansson
    The Forestry Research Institute of Sweden.
    Optimal timing of early genetic selection for sawn timber traits in Picea abies2018Ingår i: ISSN 1612-4669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In breeding Norway spruce, selection for improved growth and survival is performed at age 10–15 years in order to optimize genetic gain per year. We investigated whether a selection based on wood traits such as density and grain angle, measured under bark in the field at the same age would be informative enough with respect to structural quality traits of sawn boards. To achieve this objective, a sawing study was conducted on the butt logs of 401 trees from a 34-year-old Norway spruce progeny trial situated in southern Sweden. Stem discs were excised from the top of the logs and radial profile data of grain angle, and wood density was recorded for specific annual rings. The sawn and dried boards were assessed for structural traits such as twist, board density, bending stiffness (static modulus of elasticity, sMoE) and bending strength (modulus of rupture, MoR). Additive genetic correlations (ra) between single annual ring density measurements and board density, sMoE and MoR were consistently strong (ra> 0.7) for annual rings 5–13. Genetic correlations of similar magnitude between grain angle and board twist were estimated for all investigated annual rings (from 2 to around 26 under bark). Consequently, it was found that indirect selection for wood density and grain angle at the tree age 10–16 years would result in more genetic gain per year than selection at later ages. This makes it feasible to perform simultaneous selection of progeny in the field for both growth and wood traits at similar ages.

  • 9.
    Schweigler, Michael
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Hochreiner, Georg
    Vienna University of Technology, Austria.
    Lemaître, Romain
    University of Lorraine, France.
    Parameterization equations for the nonlinear connection slip applied to the anisotropic embedment behavior of wood2018Ingår i: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 142, s. 142-158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nonlinear numerical models for the engineering design of mechanical connections in anisotropic materials require nonlinear material behavior of their components, which are essentially determined by material or structural testing. Herein, a multi-step approach for the parameterization of the nonlinear and anisotropic connection slip behavior is presented and applied to the ductile embedment behavior of steel dowels in wood. For this purpose, previously proposed regression functions for the slip behavior are reviewed, and further possible equations are discussed. Their suitability in the description of typical shapes of slip curves observed in connection testing is assessed before certain combinations are applied to an experimental dataset of embedment tests of steel dowels embedded in Laminated Veneer Lumber. The dependence of the regression parameters on the displacement range in the experimental dataset and the benefit of using parameters with a physical interpretation for being able to exploit connection test data reported in literature is highlighted.

  • 10.
    Bader, Thomas K.
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Vessby, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Enquist, Bertil
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Path dependence in OSB sheathing-to-framing nailed connection revealed by biaxial testing2018Ingår i: Journal of Structural Engineering, ISSN 0733-9445, E-ISSN 1943-541XArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    OSB sheathing-to-wood framing connection, as typically used in light-frame shear walls, was experimentally examined in a novel biaxial test setup with respect to possible path dependence of the load-displacement relation. The connection with an annular-ringed shank nail was loaded under displacement control following nine different displacement paths within the sheathing plane, which coincided at a number of points. In intersection points, resultant connection force, its orientation and work performed on the connection system to reach the specific point were calculated and compared. Evaluation of experiments revealed significant path dependence with respect to orientation of force resultants at path intersection points. However, magnitude of the forces and the work carried out showed relatively small dependence of the displacement path undertaken. Comparison of uniaxial connection tests with the European yield model demonstrated strong contribution of withdrawal resistance of the ringed shank nail to its lateral strength. Results of this type are a valuable basis to build better models when simulating such connections in wood structures.

  • 11.
    Nilsson, Jonaz
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Requirements for wood-based lightweight panels intended for furniture and interior use2018Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Introduction: Throughout many parts of the world, forests exist in one form or another. And for the timber from these forests to be used, it must be processed by, for example, sawing into planks and dried. Studies have shown that profits for the forest owners increase from beneficial processing of these raw materials. An efficient use of this raw material is to process it into lightweight panels. Some general incentives for using lightweight constructions are: economical, technical and environmental. Some general weaknesses with sandwich constructions are more sensitive to impact and bumps, risk for delamination, harder to make fastenings, and more sensitive to the concentration of point loads. This work aims to increase the knowledge of properties and design of wood based lightweight panels used for interiors and furniture. The intention with this knowledge is that it can contribute to the development of lightweight panels.

    Material and method: A lightweight panel of cross glued sandwich type and a cross-glued multi-layered panel with densified face sheets have been used as an example to investigate and understand which parameters are crucial for a lightweight panel, made of wood. The lightweight panel of sandwich construction has been studied to consider the changes of shape brought about by moisture, as well as which mechanical properties this panel has, with a focus on creep deformation. Two methods for reducing the moisture-generated shape changes so as to increase the shape stability of the panel have also been studied. The methods are crossgluing and thermal treatment of the wood material. In the investigations of the panels, primarily quantitative methods in the form of empirical tests have been used. Some numerical simulations describing the moisture-generated shape changes and stresses that arise in the investigated lightweight panels were also made.

    Results and discussion: Cross-gluing of a multi-layered panel and also for the lightweight panel used in this study is a way to reduce the movement in the panel, generated by moisture. The drawbacks with this method are that stresses occur in the panels when the moisture change, and this can lead to a decrease in the shape stability of the panel. Thermal treatment can also be used to decrease the moisture-generated movement in wood, and in this way increase the shape stability of the product. In those cases where the empirical experiments were combined with numerical simulations, there was good agreement between the experimental and the numerical results. With the lightweight panels a weight reduction was achieved from 307 to 540 kg/m3 compared with a solid beech wood panel. The creep deformation of the lightweight panel was better or comparable for 6 of the 8 studied groups, compared to solid beech wood panel. The study also show that is possible to adapt the mechanical properties through its design of this lightweight panel.

  • 12.
    Hu, Min
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Studies of the fibre direction and local bending stiffness of Norway spruce timber: for application on machine strength grading2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Machine strength grading is a production process in the sawmill industry used to grade sawn timber boards into different strength classes with specific characteristic values of the bending strength, modulus of elasticity (MOE) and density. These properties are called grade determining properties. Each of these is predicted on the basis of a statistical relationship between the property and a so-called indicating property (IP), which is based on non-destructively assessed board properties. In most cases, the prediction of strength is crucial for the grading. The majority of commercial grading machines rely on a statistical relationship of strength to an IP, which is either a global dynamic MOE or an averaged flatwise bending MOE measured over a board length of about one meter. The problem of today’s machine strength grading is that the accuracy of the strength prediction is rather poor with a coefficient of determination of about R2 ≈ 0.5 − 0.6. One consequence of this is that much of the strength potential of timber is unused.

    The intention of this research is to contribute to a long-term goal, which is development of a method for prediction of bending strength that is more accurate than the methods available today. The research relies on three hypotheses. First, accurate prediction of bending strength can be achieved using an IP that is a localized MOE value (determined over a short length) that represents the lowest local bending stiffness of a board. Second, knowledge of the local bending stiffness with high resolution along a board’s longitudinal direction can be established on the basis of fibre direction within the board in combination with dynamic MOE. Third, fibre directions in the interior of a board can be determined by application of fibre angle models utilizing data of fibre directions on the board’s surfaces obtained from tracheid effect scanning. Following these hypotheses, this work has included laboratory investigations of local material directions, and development of models for fibre directions of the interior of boards. The work also included application of one-dimensional (1D) analytical models and three-dimensional (3D) finite element models of individual boards for the mechanical behaviour, analysis of mechanical response of boards based on experiments and based on the suggested models. Lastly, the suggested models were evaluated by comparisons of calculated and experimentally determined local bending stiffness along boards, and of predicted and experimentally determined bending strength.

    The research contributes with in-depth knowledge on local fibre directions close to knots, and detailed information on variation of the local bending stiffness in boards. Moreover, fibre angle models for fibre directions in the interior of boards are presented. By application of the fibre angle models in the 3D model of the whole board, the local bending stiffness along timber boards can be determined over a very short length (l < 50 mm). A comparison with results determined on an experimental basis show a very close similarity implying that the applied models are sufficient to capture the variation of local bending stiffness, caused by knots and fibre distortions, with very high accuracy. Furthermore, it is found that by means of IPs derived using the suggested models, bending strength can be predicted with high accuracy. For a timber sample comprising 402 boards, such IPs results in coefficient of determination as high as R2 = 0.73. However, using IPs based on the 3D finite element model did not improve the R2 value achieved when using the IPs based on the 1D model.

  • 13.
    Kumar, Anuj
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Czech Technical University in Prague, Czech Republic.
    Richter, Jan
    Czech Technical University in Prague, Czech Republic.
    Tywoniak, Jan
    Czech Technical University in Prague, Czech Republic.
    Hajek, Petr
    Czech Technical University in Prague, Czech Republic.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Šegedin, Urban
    University of Ljublijana, Slovenia.
    Marko, Petrič
    University of Ljublijana, Slovenia.
    Surface modification of Norway spruce wood by octadecyltrichlorosilane (OTS) nanosol by dipping and water vapour diffusion properties of the OTS-modified wood2018Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, nr 1, s. 45-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present research deals with a simple dipping method to insert octadecyltrichlorosilane (OTS) into cell walls of spruce wood and to deposit OTS layers on its inner and outer surfaces. Distribution and chemical interactions of OTS with wood polymers has been investigated by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The OTS/n-hexane solution penetrated into wood via capillary forces through ray tracheids and bordered pits and was deposited as OTS organic-inorganic layers on wood cell walls. The hypothesis is supported by the results, according to which the OTS molecules are hydrolysed by the wood moisture and by free OH groups of the cell wall components. The hydrolysed OTS molecules react with the OH groups and elevate the hydrophobicity of wood.

  • 14.
    Malmqvist, Cecilia
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Wallertz, Kristina
    Swedish University of Agricultural Sciences.
    Johansson, Ulf
    Swedish University of Agricultural Sciences.
    Survival, early growth and impact of damageby late‑spring frost and winter desiccation on Douglas‑firseedlings in southern Sweden2018Ingår i: New forests, ISSN 0169-4286, E-ISSN 1573-5095, s. 1-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Introduction of non-native species, such as Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), can be a means of mitigating the effects of climate change by meeting the growing demand for biomass and high quality wood. The aim of this study was to investigate early growth, survival and damage from late-spring frost and winter desiccation. A provenance trial with four coastal and three interior provenances of Douglas-fir originating from British Columbia, Canada, was established in Southwest Sweden (56°43′N, 13°08′E). Seedling height, length of the leading shoot, and occurrence of frost damage, were measured after one, three, and six growing seasons. Timing of bud break in spring was also observed. The interior Douglas-fir were more frequently damaged by late-spring frost compared to the coastal Douglas-fir. The interior Douglas-fir still had a higher survival after six growing seasons compared to the coastal variety. All provenances were damaged by winter desiccation, but the provenances originating from the coastal area were more severely damaged. Choice of variety may reduce the risk for either late-spring frost or winter desiccation.

  • 15.
    Trischler, Johann
    et al.
    Luleå University of Technology.
    Sandberg, Dick
    Luleå University of Technology.
    Dorn, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Vital gluten for particleboard production: effect of wood-particle moisture on board properties2018Ingår i: Forest products journal, ISSN 0015-7473Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The growing environmental awareness is leading to an increased interest in the use of bio-based adhesives and proteins such as vital gluten. The purpose of this study was to investigate the influence of the wood-particle moisture content, water application and press time on the internal bond strength, thickness expansion and thickness swelling of particleboards glued with vital gluten. Green and dried wood particles with similar moisture contents were achieved through drying or water addition and were blended with vital gluten powder and pressed for 1 to 3 minutes. The results show that not only the pressing time and moisture content, but also the way of achieving the moisture content has a strong impact on the performance of the boards. At comparable moisture content, never-dried (green) particles with high moisture content in combination with a dry adhesive application produced boards which performed better than boards made of dry particles with water addition to simulate liquid adhesive application.

  • 16.
    Godinho, Pedro M.J.S.
    et al.
    Vienna University of Technology, Austria.
    Jajcinovic, Marina
    Graz University of Technology, Austria.
    Bader, Thomas K.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Fischer, Wolfgang. J.
    Graz University of Technology, Austria.
    Bauer, Wolfgang
    Graz University of Technology, Austria.
    Hellmich, Christian
    Vienna University of Technology.
    A continuum micromechanics approach to the strength of planar fiber networks: paper material applications2017Ingår i: CompWood 2017 - Computational Methods in Wood Mechanics - From Material Properties to Timber Structures: Programme & Book  of Abstract / [ed] Josef Füssl, Thomas K. Bader, Josef Eberhardsteiner, Vienna: TU verlag , 2017Konferensbidrag (Refereegranskat)
  • 17.
    Scheepers, Gerhard
    et al.
    RISE Research Institutes of Sweden.
    Wiberg, Pär
    Alent Dynamic.
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    A method to estimate wood surface moisture content during drying2017Ingår i: MADERAS: Ciencia y Tecnología, ISSN 0717-3644, E-ISSN 0718-221X, Vol. 19, nr 2, s. 133-140Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method to estimate the surface moisture content below the fibre saturation point that is a function of the surface temperature, wet- and dry bulb temperatures, equilibrium moisture content, and fibre saturation point was evaluated. The method is based on the premise that the surface temperature is solely influenced by the surface moisture content and the climate that the surface is exposed to. The prediction model contends that the surface moisture content is equal to the fibre saturation point when the surface temperature is equal to the wet bulb temperature, and equal to the equilibrium moisture content when the surface temperature is equal to the dry bulb temperature, with a linear interpolation between those two points. The model thus predicts that the average moisture content of a thin piece of veneer can be predicted with fairly good accuracy. Also, when drying boards in a fast changing climate, e.g. fan reversals in industrial kilns, the surface temperature and surface moisture content should change as abruptly as the climate does. Additionally, the surface moisture content should correlate to the known drying phases, with a consistently high surface moisture content during the capillary phase when the wet line is close to the surface, and a quickly decreasing surface moisture content when the wet line moves into the wood during the transition to the diffusion phase. The prediction model was tested in these three scenarios and the results suggest that the basic premise is reasonable, and that the method is useful for surface moisture content estimation.

  • 18.
    Cristina, Simón
    et al.
    Technical University of Madrid, Spain.
    Francisco, García Fernández
    Technical University of Madrid, Spain.
    Luis, García Esteban
    Technical University of Madrid, Spain.
    Paloma, de Palacios
    Technical University of Madrid, Spain.
    Hosseinpourpia, Reza
    University of Göttingen, Germany.
    Carsten, Mai
    University of Göttingen, Germany.
    Comparison of the saturated salt and dynamic vapor sorption methods in obtaining the sorption properties of Pinus pinea L.2017Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 75, nr 6, s. 919-926Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Several methods are available for obtaining the sorption isotherms of wood. Among these, the saturated salt and dynamic vapor sorption methods are the most frequently used  ones. For the first time, the hygroscopic response of wood obtained using these two methods is compared. This is done by determining the 35 and 50°C adsorption isotherms of juvenile and mature wood of Pinus pinea L. The hygroscopic behavior of the two types of wood is different, as the mature wood has a higher moisture content than the juvenile wood in the isotherms studied. Comparison of the static saturated salt method and dynamic vapor sorption shows few significant differences between the equilibrium moisture content obtained by each method during the adsorption process, both in a point by point comparison and in the comparison of quadratic polynomial forms of the Guggenheim Anderson-de Boer model. Moreover, in both methods the point of relative humidity from which multilayer sorption predominates over monolayer sorption is similar.

  • 19.
    Josef, Füssl
    et al.
    Technische Univerität, Austria.
    Bader, Thomas K.Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).Josef, EberhardsteinerTechnische Univerität, Austria.
    CompWood 2017 - Computational Methods in Wood Mechanics - From Material Properties to Timber Structures: Programme & Book of Abstracts2017Proceedings (redaktörskap) (Refereegranskat)
  • 20.
    Schauerte, Tobias
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Lindblad, Fredrik
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Flinkman, Matti
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Critical success factors determining economic health of firms producing wooden single-family houses2017Ingår i: Arkitektur N, ISSN 1504-7628Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Firms in the Swedish industry for wooden single-family houses operate on a highly competitive market. Products are relatively homogenous, easily substitutional and firms mainly compete by prices. Since 2005, the accumulated market share for the five largest firms decreased from 53 % to 39 %, whilst the number of firms in the industry increased by almost 60 %. In addition to these internal issues on industry structure, construction firms are generally sensitive to external impacts, like the current changes in bank loan policy for the customer. Nonetheless, the number of produced single-family houses in Sweden increased by almost 130 % since 2012. Contributing to reducing the existing housing shortage in Sweden, wooden single-family house producers play an important role.

    However, earlier studies show that around 40 % of these firms are economically distressed, or in a situation, where they need to take appropriate strategic action to avoid economic distress in the near future. Yet, what actions are appropriate?

    This study is aiming at identifying current critical success factors determining economic health of Swedish firms producing wooden single-family houses. By means of these factors, conclusions about appropriate strategic actions might be drawn to avoid economic distress. Data from the 2015 annual reports of 50 relevant firms were collected and processed by means of the Altman’s Z´-score model and regression analysis.

    The results show that two factors accumulate to 99 % explanatory power (adj. R2) of financial health: (1) the manufacturing capacity of the firms’ assets and (2) the firms’ equity ratio. These are the current critical success factors for economic health of Swedish firms producing single-family houses. (1) matches todays’ debate about automated prefabrication and (2) can be seen as the way of financing such assets. Thus, these issues should guide the strategic agenda of firms in the industry.

  • 21.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Karlsson, Olov
    Luleå university of technology.
    Kumar, Anuj
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Development of sustainable bio-adhesives for engineered wood panels – A review2017Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 61, s. 38604-38630Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Changes in both formaldehyde legislations and voluntary requirements (e.g. Germany RAL) are currently the driving factors behind research on alternatives to amino-based adhesives; moreover, consumer interest in healthy and sustainable products is increasing in bio-based adhesives. Sources of formaldehyde emissions in wood-based panels as well as different emission test methods have been discussed, and the main focus of this review is on the research conducted on sustainable bio-based adhesive systems for wood panels. Lignin, tannin, protein, and starch have been evaluated as both raw materials and adhesive alternatives to existing amino-based thermosetting adhesives. Adhesion improving modifications of these bio-based raw materials as well as the available and experimental crosslinkers have also been taken into account.

  • 22.
    Malmqvist, Cecilia
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Wallin, Elisabeth
    Dalarna University.
    Lindström, Anders
    Dalarna University.
    Säll, Harald
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Differences in bud burst timing and bud freezing tolerance among interior and coastal seed sources of Douglas fir2017Ingår i: Trees, ISSN 0931-1890, E-ISSN 1432-2285, Vol. 31, nr 6, s. 1987-1998Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The need for species that will grow well through ongoing climate change has increased the interest in Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] in Sweden. One of the most common problems seen in plantations of Douglas fir seedlings is damage caused by late spring frost, known to be highly correlated with the timing of bud burst. The objective of this study was to investigate spring-related bud development under Nordic conditions of seven Douglas fir provenances and to compare data with a local provenance of Norway spruce (Picea abies (L.) Karst). Results from a field trial and a greenhouse-based study were compared. The interior Douglas fir provenances exhibited an earlier bud burst than coastal provenances, both in the greenhouse and in the field trial. When comparing differences within the groups of interior and coastal Douglas fir provenances, no differences could be found. The local Norway spruce, only grown in the greenhouse, showed an intermediate bud development profile similar to the interior Douglas fir provenance Three Valley. We therefore suggest that Three Valley could be planted at the same locations as the investigated local provenance of Norway spruce in mid-Sweden. To avoid spring frost damage the Douglas fir seedlings need to be frozen stored and planted late in spring. Planting under shelterwood can also help protect the seedlings from spring frost damages. As similar results for bud development patterns of Douglas fir and Norway spruce provenances were obtained from the greenhouse and field trials, greenhouse tests could facilitate selection of provenances.

  • 23.
    Landscheidt, Steffen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Kans, Mirka
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Winroth, Mats
    Chalmers University of Technology.
    Differences on automation practices in wooden single-family houses manufacturing: Four case studies2017Ingår i: 23rd International Wood Machining Seminar Proceedings / [ed] Marcin Zbiec and Kazimierz Orlowski, Warsaw, Poland: Warsaw University of Life Sciences , 2017, s. 350-359Konferensbidrag (Refereegranskat)
    Abstract [en]

    In densely forested countries, forest and wood-based products are an important contributing factor to the country’s economy and also a valuable resource for house manufacturing. With rising demand for housing in Europe, wooden houses have become more of an alternative to concrete houses. Although wooden houses have always been popular in Nordic countries, higher demand puts more pressure on seemingly outdated production facilities and personnel in order to supply the market. Whereas many other industries strive to modern production concepts such as Industry 4.0 to adapt to new market conditions, industrial timber house building is still characterized by a high amount of manual labor.

    In Europe´s highly industrialized countries, labor costs influence wooden house manufacturers rather negatively and exert great pressure on them to stay competitive. Some companies have chosen outsourcing of their operations and production as means to survive. Another way, already successfully proven in other industries, is the automation and digitalization of production processes. Effective implementation of automation equipment depends on several factors, e.g. production volume, applied material, chosen application or cycle times. It is not entirely clear which factors are contributing to the successful change to a more automated production.

    Based on an Industry 4.0 readiness model, the purpose of this study is to seek out which dimensions correlate with each other in order to support improved production processes and efficiency for wooden single-house manufactures. 

    By applying a comparative case study approach, automation standards and practices in Sweden, Germany and Austria, are described and compared. Results of this case study reveal that a production strategy together with sound digital support and information sharing leads to the best production systems for single-wooden houses manufacturers.

  • 24.
    Funk, Monika
    et al.
    University of Göttingen, Germany.
    Wimmer, Rupert
    Universität für Bodenkultur Vienna, Austria.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Diotomaceous earth as an inorganic additive to reduce formaldehyde emmissions from particleboards2017Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, nr 2, s. 92-97Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The presented research is about the use of a new type of a functional inorganic additive in particleboards, for the purpose of reducing free formaldehyde releases. One-layered particleboards were prepared in the laboratory by mixing industrial wood particles and urea-formaldehyde resin. Natural, abundantly and cheaply available nano-mesoporous diatomaceous earth (DE) was used, without and in combination with urea as a scavenger. Silica quartz sand was also added as a nonporous analogy. Particleboards were pressed at two press factors (9 and 15 s/mm). Formaldehyde release was determined using the rapid 3-hour-flask method (DIN EN 717-3). As a result, DE additions insignificantly reduced bending properties of particleboards. Internal bonding was in part significantly lowered. The particleboard produced with 3% urea loaded on 5% DE prior to application almost halved (–45%) the formaldehyde release. Formaldehyde release was on the average 17% lower when pressed at 15 s/mm instead of 9 s/mm. By loading urea onto the nano-mesoporous structure of DE, an improved scavenging function of urea could be shown.

  • 25.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Nilson, Henrietta
    Linnéuniversitetet, Ekonomihögskolan (FEH), Institutionen för organisation och entreprenörskap (OE).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Landscheidt, Steffen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Downtime causes in a production cell for laminated veneer products2017Ingår i: 23rd International Wood Machining Seminar Proceedings / [ed] Marcin Zbiec and Kazimierz Orlowski, Warsaw, Poland: The Polish Chamber of Commerce of Furniture Manufacturers , 2017, s. 28-35Konferensbidrag (Refereegranskat)
    Abstract [en]

    Productivity is often used to determine how well resources are used for an operation. Most often, the ratio of what is produced to what is required to produce it determines productivity. Laminated veneer products are considered complicated products often with complex shapes, a raw material with high variation, and machining processes that create scrap materials that need to be handled. Therefore, keeping a high productivity in the industries producing such products may become challenging. This study reports productivity measurements in a production cell consisting of an adhesive, pressing and processing station. The study seeks to increase understanding of production-related problems in this industry. The research has been using productivity measurement as well as interactive discussions between researchers and workers.

    Measurement of downtime causes were made for 20 days, for a total of approximately 300 hours. The production cell had 1,299 minutes of stops. Of those, 450 minutes were one-time events. The rest were intermittent disturbances. Many of them could be explained by the dust-laden air and processing residues but were also related to veneer and adhesive. There is a need for determining material and processing parameters; however, the first priority is cleaning the factory.

    From a social perspective, some other issues must be added to the discussion of this paper. First and foremost, the business has gone through a transformation from a family business to a privately held firm. From the non-family employee’s view, this is a huge change. This has resulted in unclear roles and responsibilities within the company, which has also affected the productivity of the company.

  • 26.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). University of Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Holstein, Nonna
    University of Göttingen, Germany.
    Mai, Carsten
    University of Göttingen, Germany.
    Dynamic vapour sorption and water-related properties of thermally modified Scots pine (Pinus sylvestris L.) wood pre-treated with proton acid2017Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 138, s. 161-168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigates the effect of proton acid pre-treatment and subsequent thermal modification at relatively low temperatures (up to 180 °C) on wood with respect to dimensional stability and water vapour sorption properties. The effects are compared to those of solely thermally-modified wood at higher temperatures (up to 250 °C). Scots pine sapwood (P. sylvestris L.) was impregnated with a proton acid or demineralised water, and subsequently, thermally modified to various mass losses (ML). Acid pre-treatment and thermal modification improved the dimensional stability and reduced the equilibrium moisture content (EMC) until certain ML. Excess surface work (ESW) obtained from vapour sorption studies indicated that, at comparable ML, the acid pre-treatment reduced the available sorption sites as compared to sole thermal treatment. Samples pre-treated with acid also showed stronger decreasing courses of EMC- and ESW-ratios than sole thermally modified ones. This was attributed to degradation of amorphous wood polymers and a stiffer matrix due to cross-linking of the cell wall polymers as a consequence of acid pre-treatment. Electron spin resonance (ESR) analysis indicated that acid pre-treatment did not enhance the concentration of phenoxy radicals, whereas thermally modified wood showed a considerably higher concentration of phenoxy radicals, suggesting that high radical density cannot be used as an indicator for high matrix stiffness.

  • 27.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Georg-August-University, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Mai, Carsten
    Georg-August-University, Gemany.
    Hemmilä, Venla
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Effect of Bio-Based Additives on Physico-Mechanical Properties of Medium Density Fibreboards2017Ingår i: 28th International Conference on Wood Science and Technology (ICWST), Zagreb, Croatia, 7-8 December, 2017 / [ed] Ivica Zupcic; Vjekoslav Zivkovic; Josip Miklecic, University of Zagreb, Faculty of Forestry , 2017, s. 153-158Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dimensional stability of wood-based panels is generally improved with application of suitable additives. Most of these additives, such as paraffin wax, are petroleum-based and with relatively high cost, and therefore, it is desirable to develop low-cost and effective substitutes from renewable resources. This work studied the potential of using a renewable water-repellent additive, such as tall oil fatty acid, for lab-scale manufacturing of medium density fibreboards (MDF). Tall oil fatty acid (TOFA) was used at 1 and 3% w/w of urea formaldehyde (UF) resin. MDF panels with similar concentrations of paraffin wax (wax) and panels without adding a water-repellent agent were served as controls. It was assessed the dimensional stability of the panels in terms of thickness swelling and water uptake after 4 and 24h immersion in water, and their mechanical performance in terms of modulus of elasticity, modulus of rupture and internal bonding. Results showed no obvious differences in the strength behaviour of the panels by addition of water-repellent agents. Dimensional stability, however, considerably improved by addition of TOFA, but it was still inferior when compared to that provided by wax.   

  • 28.
    Ahmed, Sheikh Ali
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Morén, Tom
    Luleå University of Technology.
    Sehlstedt-Persson, Margot
    Luleå University of Technology.
    Blom, Åsa
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Effect of oil impregnation on water repellency, dimensional stability and mold susceptibility of thermally-modified European aspen and downy birch wood2017Ingår i: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 63, nr 1, s. 74-82Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Conventional chemical wood preservatives have been banned or restricted in some applications due to human and animal toxicity and their adverse impact on the surrounding environment. New, low-environmental-impact wood treatments that still provide effective protection systems are needed to protect wood. Thermal modification of wood could reduce hygroscopicity, improve dimensional stability and enhance resistance to mold attack. The aim of this study was to investigate if these properties enhanced in thermally modified (TM) wood through treatments with oils. In this study, TM European aspen (Populus tremula) and downy birch (Betula pubescens) wood were impregnated with three different types of oil: water-miscible commercial Elit Träskydd (Beckers oil with propiconazole and 3-iodo-2-propynyl butylcarbamate, IPBC), a pine tar formulation and 100% tung oil. The properties of oil-impregnated wood investigated were water repellency, dimensional stability and mold susceptibility. The treated wood, especially with pine tar and tung oil, showed an increase in water repellency and dimensional stability. However, Beckers oil which contains biocides like propiconazole and IPBC showed better protection against mold compared with pine tar and tung oil. To enhance the dimensional stability of the wood, pine tar and tung oil can be used, but these oil treatments did not significantly improve mold resistance rather sometimes enhanced the mold growth, whereas a significant anti-mold effect was observed on Beckers oil treated samples.

  • 29.
    Bastani, Alireza
    et al.
    University of Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Militz, Holger
    University of Göttingen, Germany.
    Effect of open assembly time and equilibrium moisture content on the penetration of polyurethane adhesive into thermally modified wood2017Ingår i: The journal of adhesion, ISSN 0021-8464, E-ISSN 1563-518X, Vol. 93, nr 7, s. 575-583Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of wood moisture content and open assembly time on penetration of polyurethane (PU) adhesive into thermally treated Scots pine (195 and 210°C) was investigated according to effective (EP) and maximum penetration (MP) measurements using fluorescence microscopy. For samples treated at 195°C, a higher EP was noted at 8.6% equilibrium moisture content (EMC) after both assembly times (15 and 30 min) while for samples treated at 210°C, increasing wood moisture content resulted in a significant decrease in EP at 12.5% EMC after 15 min assembly time. Extending open assembly time was found to increase the EP of PU adhesive only in the case of samples treated at 195°C and with 8.6% EMC. For samples treated at both treatment temperatures and after shorter open assembly time, the highest MP observed at moderate EMC levels of 8.6 and 8.2% and the lowest at the higher EMC levels of 13.2 and 12.5%.

  • 30.
    Jensen, Anna M.
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Löf, Magnus
    Swedish University of Agricultural Sciences.
    Effects of interspecific competition from surrounding vegetation on mortality, growth and stem development in young oaks (Quercus robur)2017Ingår i: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 392, s. 176-183Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Facilitation by a neighboring woody understory has been suggested as a cost-effective and sustainable way to regenerate oaks. However, concerns about reduced plant growth and quality due to competing neighboring vegetation have hindered implementation. Here we studied competitive effects from herbaceous and woody vegetation on survival, growth, canopy development and stem quality in pedunculate oak (Quercus robur) in an open-field experiment in southern Sweden. Oaks were grown for eight years in four different competition treatments: no competing vegetation, with herbaceous vegetation (mainly grasses), with woody vegetation, and with both herbaceous and woody vegetation. During the first four years, competition had little effect on oak survival. However, after eight growing seasons, survival rates decreased to about 20% for oaks surrounded by woody vegetation, in contrast to oaks grown with only herbaceous vegetation that had a survival rate of near 100%. Competition from herbaceous and woody vegetation both reduced oak stem diameter and height growth, but they affected height growth differently. During the first growing seasons, oaks in the treatment with woody vegetation were able to keep up with the height growth of the surrounding vegetation. Thereafter, height growth stagnated, and after eight growing seasons heights of oaks in the treatment with woody competitors were only 30–39% that of oaks in the treatment without competing vegetation. In contrast, competition from herbaceous vegetation only restricted oak height development marginally. Interspecific competition not only restricted growth and survival but also shifted shoot architecture, resulting in a greater frequency of oaks with straight monopodial stems. Although competition from both herbaceous- and woody vegetation positively affected stem straightness, plots with woody vegetation had a greater proportion (0.42) of oaks with a single straight monopodial stem. Our results demonstrate that the facilitative competitive effects from herbaceous and woody vegetation could be used to control allocation patterns in young oaks, promoting development of tall straight monopodial stems. Considering the observed trade-off between high stem quality and survival, we recommend long-term assessment of this trade-off prior to application in practical forestry.

  • 31.
    Taghiyari, Hamid Reza
    et al.
    Shahid Rajaee University, Iran.
    Hosseinpourpia, Reza
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Jahangiri, Asghar
    Rabie, Davood
    Effects of Nano-Wollastonite Impregnation on Fire Properties of Some Thermally-Treated Solid Wood Species2017Ingår i: Proceedings IRG Annual Meeting, IRG/WP 17-40771, International research group on wood protection , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    The effects of nano-wollastonite (NW) suspension impregnation on the fire-retarding properties of heat-treated solid wood of three species (beech, poplar, fir) were studied. Heat treatment was performed at two temperatures of 180 °C and 200 °C. Impregnation was carried out at a pressure of 3 bars for 30 min. The fire properties included ignition time, glowing time, back-darkening, back-splitting, back-firing, and length and width of the burnt area. Both impregnation with NW and heat-treatment generally improved all fire-retarding properties, although not always to a significant level. As a mineral material, NW acted like a physical shield against fire penetration into the texture of wood specimens, thus improving fire properties. Moreover, the high thermal conductivity coefficient of wollastonite increased the thermal conductivity of wood, therefore preventing the accumulation of heat at the point nearest to a piloted flame and contributing to the improvement of fire properties. The chemical degradation of wood cell components caused by heat-treatment further improved the fire properties. Cluster analysis indicated the significant effect of species on fire properties. Significant R-square values were found amongst fire properties related to the spread of fire on the surface of specimens. The combination of thermal modification and impregnation with NW provides suitable fire properties for solid wood.

  • 32.
    Ormarsson, Sigurdur
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Johansson, Marie
    SP.
    FE-modell av en volymmodul - spännings- och stabilitetsanalys : Förstudie2017Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Trä är ett mycket användbart, prisvärt och förnyelsebart material som rätt utnyttjat har en extremt hög industriell potential inom området byggnadskonstruktion. Det finns ett stort intresse i Sverige att utforska nya sätt att utnyttja trä som huvudlastbärande material i olika typer av flervåningshus. Detta är en stor utmaning för träbyggnadsindustrin, forskare och konstruktörer eftersom det inte finns någon traditionell beräknings- och designprocedur för dessa typer av byggnader.

    I denna förstudie har en parametrisk FE-modell framtagits för att studera strukturmekaniska egenskaper (deformationer och styvhet) hos en typisk volymmodul som används för byggande av flerbostadshus i trä. Modellen är uppbyggd av olika typer av strukturelement (fjädrar, balk- och skalelement) för att den skall vara så snabb och flexibel som möjligt. Modellen inkluderar ett stort antal konnektor- och kopplingselement för att på ett optimalt sätt kunna simulera alla spik-, skruv- och bultförband i modulen. Modellen är också ganska flexibel eftersom den är parameterstyrd via ett antal geometriska parametrar. Modellen har använts för att studera globala deformationer och styvhetsegenskaper hos olika vägg- och volymelement när de belastas med olika mekaniska laster. Att få en uppfattning om hur styvhetsegenskaper hos de mekaniska förbanden (svaga delar i konstruktionen) påverkar det globala deformationsbeteendet hos olika vägg- och volymelement har varit en viktig del i denna förstudie.

    Modellen visar ett deformationsbeteende hos vägg- och volymelementen verkar rimliga men en experimentell verifiering återstår. Ett exempel på resultat är att väggelement som belastas i planskjuvning har en tydlig tendens att böja ut ur planet eftersom det finns gipsskiva enbart på insidan av regelstommen. Studien visar också att för volymmoduler med en gles skruvförbindning mellan vägg- och bjälklagselementen uppkommer stora gliddeformationer mellan elementen. En av de viktigaste slutsatser från denna förstudie är att det gick att skapa en snabb och effektiv strukturmekanisk tredimensionell FE-modell för den här typen av konstruktion. Beräkningstiden för en volymmodul var endast 5.5 minuter på en vanlig laptop computer. Dessa resultat visar därför att det finns goda förutsättningar för att kunna simulera och analysera hela flerbostadshus inom rimliga beräkningstider.

  • 33.
    Kumar, Anuj
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Vlach, Tomáš
    Czech Technical University in Prague, Czech Republic.
    Ryparovà, Pavla
    Czech Technical University in Prague, Czech Republic.
    Sever Škapin, Andrijana
    Slovenian National Building and Civil Engineering Institute, Slovenia.
    Kovač, Janez
    Jožef Stefan Institute, Slovenia.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Hajek, Petr
    Czech Technical University in Prague, Czech Republic.
    Petrič, Marko
    University of Ljubljana, Slovenia.
    Influence of liquefied wood polyol on the physical-mechanical and thermal properties of epoxy based polymer2017Ingår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 64, s. 207-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Epoxy resins are mostly produced from petroleum-based bisphenol A and epicholorhydrin. Bisphenol A is synthesized from non-renewable petroleum-based phenol and acetone. Biomass derived epoxy-based polymers (EBPs) are becoming the most promising alternative for petroleum-based counterparts, but still these biomass-based EBPs have inferior properties. In the present work, two types of epoxy resins were prepared with different weight percentages of resin (bisphenol A) and hardener. They were then modified with different weight percentages of liquefied wood from spruce sawdust. The derived EBPs were analysed in terms of tensile strength and tensile modulus, fractured surface morphology, thermal stability, long-term water adsorption and resistance to brown-rot fungus decay. The results revealed that the percentages of hardener and liquefied wood significantly influenced the overall properties of the EBPs.

  • 34.
    Norby, Richard J.
    et al.
    Oak Ridge National Laboratory, USA.
    Gu, Lianhong
    Oak Ridge National Laboratory, USA.
    Haworth, Ivan C.
    Oak Ridge National Laboratory, USA.
    Jensen, Anna M.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Oak Ridge National Laboratory, USA.
    Turner, Benjamin L.
    Smithsonian Tropical Research Institute, Panama.
    Walker, Anthony P.
    Oak Ridge National Laboratory, USA.
    Warren, Jeffrey M.
    Oak Ridge National Laboratory, USA.
    Weston, David J.
    Oak Ridge National Laboratory, USA.
    Xu, Chonggang
    Los Alamos National Laboratory, USA.
    Winter, Klaus
    Smithsonian Tropical Research Institute, Panama.
    Informing models through empirical relationships between foliar phosphorus, nitrogen and photosynthesis across diverse woody species in tropical forests of Panama2017Ingår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 215, nr 4, s. 1425-1437Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Our objective was to analyze and summarize data describing photosynthetic parameters and foliar nutrient concentrations from tropical forests in Panama to inform model representation of phosphorus (P) limitation of tropical forest productivity.

    Gas exchange and nutrient content data were collected from 144 observations of upper canopy leaves from at least 65 species at two forest sites in Panama, differing in species composition, rainfall and soil fertility. Photosynthetic parameters were derived from analysis of assimilation rate vs internal CO2 concentration curves (A/Ci), and relationships with foliar nitrogen (N) and P content were developed.

    The relationships between area-based photosynthetic parameters and nutrients were of similar strength for N and P and robust across diverse species and site conditions. The strongest relationship expressed maximum electron transport rate (Jmax) as a multivariate function of both N and P, and this relationship was improved with the inclusion of independent data on wood density.

    Models that estimate photosynthesis from foliar N would be improved only modestly by including additional data on foliar P, but doing so may increase the capability of models to predict future conditions in P-limited tropical forests, especially when combined with data on edaphic conditions and other environmental drivers.

  • 35.
    Bader, Thomas K.
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Schweigler, Michael
    Technische Universität Wien, Austria.
    Hochreiner, Georg
    Technische Universität Wien, Austria.
    Eberhardsteiner, Josef
    Technische Universität Wien, Austria.
    Ingenieurmodelle für die Strukturmodellierung und Nachweisführung von stiftförmigen Verbindungen im Holzbau: (Engineering models for the structural design and verification of dowel-type connections in timber structures)2017Ingår i: Österreichische Ingenieur- und Architekten-Zeitschrift, ISSN 0721-9415, Vol. 162, nr 1-12, s. 1-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Connections of elements in timber structures play an important role, not only due to their pronounced effect on the mechanical behavior of structures, but also due to the fact they can be decisive for the economic success of timber structures. Herein, approaches for a calculation of the ductile load-displacement behavior of dowel-type connections, of multi-dowel joints and of stresses in their timber matrix, by means of numerical methods, are presented. With these methods, kinematically compatible relative deformations of joints under arbitrary plane loading conditions and their effect on the mechanical behavior of timber structures can be reasonably predicted. The combination of the presented models and their integration in the structural analysis and the verification of timber structures lead to a more realistic prediction of their behavior (internal forces, stresses and deformations), as well as to a more economic design of timber structures. 

  • 36.
    Bader, Thomas K.
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Vessby, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Modeling displacement path dependence in nailed sheathing-to-framing connections2017Ingår i: CompWood 2017 - Computational Methods in Wood Mechanics - from Material Properties to Timber Structures: Programme & Books of Abstracs / [ed] Josef Füssl, Thomas K. Bader, Josef Eberhardsteiner, Vienna: TU verlag , 2017Konferensbidrag (Refereegranskat)
  • 37.
    Nilsson, Jonaz
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Moisture-related distortion and damage of lightweight wood panels: experimental and numerical study2017Ingår i: Journal of the Indian Academy of Wood Science, ISSN 0972-172X, Vol. 14, nr 2, s. 00-109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study was conducted to increase the knowledge of moisture-related distortion and damage in the field of wood-based lightweight panels. By increasing the possibilities of predicting moisture-related distortion and damage, the possibilities of using lightweight wood materials could increase. The study was performed through experiments and modelling work on a wooden panel product with numerous struts and two thin outer-face sheets of beech-wood glued tightly onto the struts, as well as reference panels of solid wood. During the testing period the results showed the density of the studied lightweight panels to vary from 170 to 290 kg/m3. These panels shrunk and swelled less than the solid wood panels and reacted faster to changes of surrounding humidity and temperature. Moisture related distortions such as twist and bow were not inferior compared to the solid wood panels. Shrinkage or swelling produced moisture related stresses. This may mean that the panel will have a risk of serious damage in the form of cracks or glue release between the outer face sheet and the struts when it is exposed to intense drying. The experimental tests also followed how various damages arose in the panels. Until the damage occurred, the deformation results showed a strong agreement between the experimental and the model findings. Better knowledge of how this type of panel reacts to climate variations is important for the further design and development of this type of product.

  • 38.
    Bader, Thomas K.
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Bocquet, Jean-Francois
    University of Lorraine, France.
    Schweigler, Michael
    Vienna University of Technology, Austria.
    Lemaitre, Romain
    University of Lorraine, France.
    Numerical modeling of the load distribution in multiple fastener joints2017Ingår i: International Conference on Connections in Timber Engineering – From Research to Standards: Proceedings of the Conference of COST Action FP1402 at Graz University of Technology / [ed] Reinhard Brandner, Andreas Ringhofer & Philipp Dietsch, Graz: Verlag der Technischen Universität Graz , 2017, s. 136-152Konferensbidrag (Refereegranskat)
    Abstract [en]

    Numerical modeling approaches, for the determination of load distribution in laterally loaded joints, as well as for the assignment of stiffness properties of joints for the structural analysis, are summarized in this contribution. The effect of the nonlinearity and the load-to-grain orientation dependence of connection slip, of elastic deformation in the surrounding wood matrix, and of the deviation between load and displacement direction are discussed. Comparison of various models demonstrates the pronounced effect of the load-to-grain orientation dependence and the nonlinearity in connection slip on the load distribution, particularly in case of moment loading. The effect of elastic deformation in the wood matrix on the load distribution increases with increased size of joints, even more pronounced when joints are loaded by a shear force perpendicular to the grain. In case of normal force loading, the non-uniform load distribution due to elastic deformation in the wood matrix reduces rapidly with increased relative joint displacement. Pros and cons of the modeling approaches as well as necessary input data are discussed in relation to the design process and European standardization.

  • 39.
    Ormarsson, Sigurdur
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Johansson, M.
    Numerical simulations of structural behaviour of volume modules used for construction of multifamily timber houses2017Ingår i: CompWood 2017 : Computational Methods in Wood Mechanics – from Material Properties to Timber: Programme & Book of abstract, 2017Konferensbidrag (Refereegranskat)
  • 40.
    Landscheidt, Steffen
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Kans, Mirka
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Winroth, Mats
    Chalmers University of Technology.
    Opportunities for robotic automation in wood product industries: The supplier and system integrators' perspective2017Ingår i: 27th International Conference on Flexible Automation and Intelligent Manufacturing, FAIM2017 / [ed] Pellicciari, M; Peruzzini, M, Elsevier, 2017, s. 233-240Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study, the opportunities for automation in the poorly automated wood product industry are highlighted. This isaccomplished by conducting a qualitative interview study of suppliers and system integrators for industrial robots active in thisparticular industry sector. Five case companies are chosen in order to explore the unique dimensions responsible for successfulautomation implantation in wood product companies. Results show that a low understanding of automation opportunities, unclearrequirements specifications, and small production volumes are the main problems for suitable automation solutions. Althoughwood is a fragile and changeable material, existing technology allows its manipulation with industrial robots.

  • 41.
    Hedwall, Per-Ola
    et al.
    Swedish University of Agricultural Science.
    Bergh, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Brunet, Jorg
    Swedish University of Agricultural Science.
    Phosphorus and nitrogen co-limitation of forest ground vegetation under elevated anthropogenic nitrogen deposition2017Ingår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 185, nr 2, s. 317-326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plant growth in northern forest ecosystems is considered to be primarily nitrogen limited. Nitrogen deposition is predicted to change this towards co-limitation/limitation by other nutrients (e.g., phosphorus), although evidence of such stoichiometric effects is scarce. We utilized two forest fertilization experiments in southern Sweden to analyze single and combined effects of nitrogen and phosphorus on the productivity, composition, and diversity of the ground vegetation. Our results indicate that the productivity of forest ground vegetation in southern Sweden is co-limited by nitrogen and phosphorus. Additionally, the combined effect of nitrogen and phosphorus on the productivity was larger than when applied solely. No effects on species richness of any of these two nutrients were observed when applied separately, while applied in combination, they increased species richness and changed species composition, mainly by promoting more mesotrophic species. All these effects, however, occurred only for the vascular plants and not for bryophytes. The tree layer in a forest has a profound impact on the productivity and diversity of the ground vegetation by competing for both light and nutrients. This was confirmed in our study where a combination of nitrogen and high tree basal area reduced cover of the ground vegetation compared to all the other treatments where basal area was lower after stand thinning. During the past decades, nitrogen deposition may have further increased this competition from the trees for phosphorus and gradually reduced ground vegetation diversity. Phosphorus limitation induced by nitrogen deposition may, thus, contribute to ongoing changes in forest ground vegetation.

  • 42.
    Malmqvist, Cecilia
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Planting and survivability of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) in Sweden: Questions of seedling storability, site preparation, bud burst timing and freezing tolerance2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The non-native Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) has been grown to a limited extent in the southern part of Sweden since the early 1900s. A more extensive use has probably been curtailed by its known susceptibility to damage by frost, pine weevil and other pests. Limited access to vital seedlings of suitable provenances has also restricted its more widespread growth. The need for valuable species that will grow well through ongoing climate change has increased the interest for Douglas fir in Sweden.

    This thesis addresses a number of important questions relating to the planting of Douglas fir in Sweden: seedling storability, freezing tolerance, timing of bud burst, frost damage and seedling response to site preparation. Seven Douglas fir provenances originating from British Columbia, Canada were used in the experiments and where applicable, compared with a local provenance of Norway spruce (Picea abies (L.) Karst.). The early bud burst of interior Douglas fir provenances, observed both in greenhouse tests and in the field, results in a high risk of damage by late spring frost. This type of damage does not seem, however, to be fatal and does not obviously retard the early growth of seedlings. The difference in growth between coastal and interior provenances was insignificant, but survival was greater for interior than for coastal provenances. All the provenances of Douglas fir studied showed a later development of freezing tolerance of shoots and roots in the autumn than Norway spruce, with the coastal provenances developing such tolerance even later than interior provenances. This could be a contributory cause for the severe damage by winter desiccation observed on seedlings of coastal origin. A thorough site preparation proved to be an effective way to increase survival and root growth. Interior provenances of Douglas fir became ready for storage earlier in autumn than coastal provenances. When freezing tolerance of shoots had increased sufficiently, Douglas fir seedlings could safely be kept in frozen storage using the same procedures used for Norway spruce. The results emphasise the need to gain further knowledge about how the remaining obstacles to establishment of Douglas fir could be reduced with different silviculture methods.

  • 43.
    Popovic, Djordje
    et al.
    Jönköping university.
    Schauerte, Tobias
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Prefabrication of single-family timber houses: problem areas and wastes2017Ingår i: Proceedings of the 25th Annual Conference of the International Group for Lean Construction (IGLC) / [ed] Walsh, K., Sacks, R., Brilakis, I., Heraklion, Greece: International Group for Lean Construction (IGLC) , 2017, Vol. 2, s. 837-844Konferensbidrag (Refereegranskat)
    Abstract [en]

    Industrialization of house building has shifted the activities traditionally done at building site to the off-site assembly. The design, manufacturing processes and on-site assembly in industrialized house building are defined and documented to form a process platform, but these must be evaluated and improved to constantly develop better and more efficient practice. Lean production and philosophy are still not well understood concepts at the shop floor and wasteful activities that decrease production efficiency are often overseen. Current waste categorizations and descriptions seem not to be addressing problem areas and occurrence of waste in prefabrication of single family timber houses. The research aim is to define problem areas that occur during the prefabrication of wall modules, associate them to eight types of waste and identify key problem areas for possible development and improvement. The study was based on secondary data from five case studies that primarily focused on identifying and proposing possibilities for development of productivity. Four problem areas were identified and the future improvement efforts for the prefabrication of single family houses can be placed on developing the processes of the assembly system problem area. The possible future study can aim at quantifying these problem areas.

  • 44.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Landscheidt, Steffen
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Nilson, Henrietta
    Linnéuniversitetet, Ekonomihögskolan (FEH), Institutionen för organisation och entreprenörskap (OE).
    Resource utilization in a production cell for laminated veneer products2017Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, nr 4, s. 142-147Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The concept of productivity is often used to determine how well resources are used in an operation, and it is usually determined as the ratio of what is consumed in the production. Laminated veneer products are considered complicated products often taking complex shapes, using a raw material with high variation, and requiring machining processes that create scrap material that needs to be handled. Therefore, maintaining high productivity in industries producing such products may become challenging. This study reports on productivity measurements in a production cell consisting of an adhesive, pressing and a processing station. The study seeks to increase the understanding of production-related problems in this industry. This research has been based on productivity measurement as well as on interactive discussions between researchers and workers. Measurement of cycle times indicated bottlenecks in the processing cell. The discussion led via cycle times, processing residues and chatter marks to an examination of the foundation and rigidity of the CNC-machine in the processing cell. The study indicated that the performance of the CNC machine did not correspond to expectations. The machine was too weak to handle the required output in an efficient manner. Thus, there is a need to determine the performance expected before a machine or machine group is purchased. An update of the existing purchasing literature and its dissemination will support the crystallization of the purchasing process as a way forward to support the industry.

  • 45.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Shear stiffness and its relation to the microstructure of 10 European and tropical hardwood species2017Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, nr 2, s. 82-91Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, shear stiffness properties of 10 different hardwood species and their relation to the corresponding species-specific microstructure are investigated. For this purpose, shear stiffness of 10 different hardwood species is experimentally measured by means of ultrasonic testing. In addition, a micromechanical model for hardwood is applied in order to illustrate the influence of certain microstructural characteristics such as mass density and volume fractions of vessels and ray cells on the shear stiffness. Comprehensive microstructural and mechanical data from previous investigations of the same hardwood material support the interpretation of the microstructure–shear stiffness relationships. Mass density was confirmed to be the dominant microstructural characteristic for shear stiffness. Also, ultrasound shear wave propagation velocity increases with density, particularly in the radial-tangential (RT) plane. In addition to density, comparably higher shear stiffness GLR can be explained by comparably higher ray content and lower vessel content. As for GLT, a ring porous structure seems to lead to higher shear stiffness as compared to a diffuse porous structure. For this shear stiffness, vessel and ray content were found to have a less impact. Also, the rolling shear stiffness GRT was found to be higher for a diffuse porous structure than for a ring porous one. Moreover, the data supports that ray cells act as reinforcements in the RT plane and lead to higher GRT

  • 46.
    Bastani, Alireza
    et al.
    University of Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Militz, Holger
    University of Göttingen, Germany.
    Shear strength of furfurylated, N-methylol melamine and thermally modified wood bonded with three conventional adhesives2017Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, nr 4, s. 236-241Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The shear strength of furfurylated, N-methylol melamine (NMM) and thermally modified wood bonded with emulsion polymer isocyanate, polyvinyl acetate (PVAc), and polyurethane (PU) adhesives was examined. Furfurylation and NMM modification of Scots pine had a significant negative effect on the bonding strength with all adhesives irrespective of the treatment intensity. The obtained low-shear strength values were related to the brittle nature of the wood after modifications rather to the failure of the bondline. PVAc showed a better bonding performance with both furfurylated and NMM modified wood while the combination of furfurylated wood and PU gave the highest reduction in bonding strength (47–51%). Shear strength also decreased significantly after thermal modification in both Scots pine (36–56%) and beech (34–48%) with all adhesives. With the exception of thermally modified beech samples bonded with PU, bondline was found to be the weakest link in thermally modified wood as it was revealed by the wood failure surfaces. Bondline thickness and effective penetration of adhesives did not relate to the shear strength of all modified wood materials. The lower shear strength of modified wood could be attributed to other factors, such as the reduced chemical bonding or mechanical interlocking of adhesives, and the reduced strength of brittle modified wood substrate.

  • 47.
    Malmqvist, Cecilia
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Wallertz, Kristina
    Swedish University of Agricultural Sciences.
    Lindström, Anders
    Dalarna University ; Swedish University of Agricultural Sciences.
    Storability and freezing tolerance of Douglas fir and Norway spruce seedlings grown in mid-Sweden2017Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 32, nr 1, s. 30-38Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate change provides new challenges to Nordic forestry. Use of non-native species, such as Douglas fir, can be a means of mitigating the effects of climate change and meeting the growing demand for biomass. When Douglas fir is grown in Sweden, it is several degrees of latitude north of its normal range, which can affect timing of growth cessation, hardening of seedlings, and seedling storability. The objective of this study was to investigate tolerance to freezing and sub-zero storability of seven Douglas fir provenances and make comparisons with the native Norway spruce. Freezing tolerance and storability were evaluated by measuring the electrolytic leakage of shoots and roots after freezing, complemented with a three-week cultivation test after storage. All provenances of Douglas fir used in this study were able to tolerate frozen storage at −4°C for about four months. Norway spruce and the interior Douglas fir provenance, Three Valley, could be stored earlier in the autumn than the southern coastal Douglas fir provenances. Consequently, it should be possible to store Douglas fir seedlings with the same routines as for Norway spruce.

  • 48.
    Hochreiner, Georg
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Schweigler, Michael
    Vienna University of Technology, Austria.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Structural behaviour and design of dowel groups: experimental and numerical identification of stress states and failure mechanisms of the surrounding timber matrix2017Ingår i: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 131, s. 421-437Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dowel-type fasteners in combination with steel plates are widely used in engineered timber structures. Since dowel groups are designed as semi-rigid connections subjected to an arbitrary set of internal forces, the corresponding structural behaviour of the surrounding timber matrix must be considered in the design process accordingly, including the effect of reinforcements. Corresponding stress states and failure mechanisms in the timber matrix of dowel groups are discussed herein. Surface strain fields from tests of dowel groups under complex loading situations were used to identify the sequence of cracking, as well as to assign the related failure modes. First cracking events were caused by stress peaks at the most loaded dowels and by a combination of shear stresses and stresses perpendicular to the grain, while later crack- ing events were associated with a predominant action of individual stress components. Thus, the non- linear global moment-relative rotation behaviour of dowel groups could be related to failure mechanisms in the surrounding timber matrix. The corresponding strain state was qualitatively as well as quantita- tively reproduced by means of a numerical model, which gave access to stresses in the timber matrix and has potential to be implemented as a sub-model in engineering design software. The numerical model supported the feasibility of a decomposition of the stress state due to the global bending moment into stresses caused by a couple of equal forces parallel and perpendicular to the grain, which could be used in the design process. Based on experimental and numerical findings, essential aspects for a design procedure for the timber matrix in dowel groups loaded by a combination of internal forces are proposed. 

  • 49.
    Griffiths, Natalie A.
    et al.
    Oak Ridge Natl Lab, USA.
    Hanson, Paul J.
    Oak Ridge Natl Lab, USA.
    Ricciuto, Daniel M.
    Oak Ridge Natl Lab, USA.
    Iversen, Colleen M.
    Oak Ridge Natl Lab, USA.
    Jensen, Anna M.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Oak Ridge Natl Lab, USA.
    Malhotra, Avni
    Oak Ridge Natl Lab, USA.
    McFarlane, Karis J.
    Lawrence Livermore Natl Lab, USA.
    Norby, Richard J.
    Oak Ridge Natl Lab, USA.
    Sargsyan, Khachik
    Sandia Natl Labs, USA.
    Sebestyen, Stephen D.
    USDA Forest Serv, USA.
    Shi, Xiaoying
    Oak Ridge Natl Lab, USA.
    Walker, Anthony P.
    Oak Ridge Natl Lab, USA.
    Ward, Eric J.
    Oak Ridge Natl Lab, USA.
    Warren, Jeffrey M.
    Oak Ridge Natl Lab, USA.
    Weston, David J.
    Oak Ridge Natl Lab, USA.
    Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment2017Ingår i: Soil Science Society of America Journal, ISSN 0361-5995, E-ISSN 1435-0661, Vol. 81, nr 6, s. 1668-1688Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We are conducting a large-scale, long-term climate change response experiment in an ombrotrophic peat bog in Minnesota to evaluate the effects of warming and elevated CO2 on ecosystem processes using empirical and modeling approaches. To better frame future assessments of peatland responses to climate change, we characterized and compared spatial vs. temporal variation in measured C cycle processes and their environmental drivers. We also conducted a sensitivity analysis of a peatland C model to identify how variation in ecosystem parameters contributes to model prediction uncertainty. High spatial variability in C cycle processes resulted in the inability to determine if the bog was a C source or sink, as the 95% confidence interval ranged from a source of 50 g C m(-2) yr(-1) to a sink of 67 g C m(-2) yr(-1). Model sensitivity analysis also identified that spatial variation in tree and shrub photosynthesis, allocation characteristics, and maintenance respiration all contributed to large variations in the pretreatment estimates of net C balance. Variation in ecosystem processes can be more thoroughly characterized if more measurements are collected for parameters that are highly variable over space and time, and especially if those measurements encompass environmental gradients that may be driving the spatial and temporal variation (e.g., hummock vs. hollow microtopographies, and wet vs. dry years). Together, the coupled modeling and empirical approaches indicate that variability in C cycle processes and their drivers must be taken into account when interpreting the significance of experimental warming and elevated CO2 treatments.

  • 50.
    Cintas, Olivia
    et al.
    Chalmers University of Technology.
    Berndes, Göran
    Chalmers University of Technology.
    Hansson, Julia
    Chalmers University of Technology ; IVL Swedish Environmental Research Institute.
    Poudel, Bishnu Chandra
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Bergh, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Börjesson, Pål
    Lund University.
    Egnell, Gustaf
    Swedish University of Agricultural Sciences.
    Lundmark, Tomas
    Swedish University of Agricultural Sciences.
    Nordin, Annika
    Swedish University of Agricultural Sciences.
    The potential role of forest management in Swedish scenarios towards climate neutrality by mid century2017Ingår i: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 383, nr Special Issue, s. 73-84Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Swedish climate policy targets net zero greenhouse gases (GHG) by mid-century, with road transport independent of fossil fuels by 2030, requiring far-reaching changes in the way energy is used. Forest management is expected to support carbon sequestration and provide biomass for various uses, including energy. In this paper, we combine two energy scenarios with four forest scenarios and quantify GHG balances associated with energy-use for heat, electricity, and road transport, and with forest management and production, use, and end-of-life management of various forest products, including products for export. The aggregated GHG balances are evaluated in relation to the 2-degree target and an allocated Swedish CO2 budget. The production of biofuels in the agriculture sector is considered but not analyzed in detail.

    The results suggest that Swedish forestry can make an important contribution by supplying forest fuels and other products while maintaining or enhancing carbon storage in vegetation, soils, and forest products. The GHG neutrality goal is not met in any of the scenarios without factoring in carbon sequestration. Measures to enhance forest productivity can increase output of forest products (including biofuels for export) and also enhance carbon sequestration. The Swedish forest sector can let Sweden reach net negative emissions, and avoid “using up” its allocated CO2 budget, thereby increasing the associated emissions space for the rest of the world.

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