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  • 251.
    Elustondo, Diego
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Guest Editorial: R&D Needs in Wood Drying Technology2014In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 32, no 6, p. 629-630Article in journal (Other academic)
  • 252.
    Elustondo, Diego
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ahmed, Sheikh Ali
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Oliveira, Luiz
    Department of Lumber Manufacturing, FPInnovations, Vancouver.
    Drying Western Red Cedar with Superheated Steam2014In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 32, no 5, p. 550-556Article in journal (Refereed)
    Abstract [en]

    This exploratory study evaluated the possibility of drying 50-mm-thick western red cedar with superheated steam. Since there are no industrial facilities in Canada drying western red cedar with superheated steam, the study was designed to explore the potential of this technology in terms of lumber quality, moisture content distribution, and drying time. The experiments showed that the 50-mm-thick product can be dried in less than three days without jeopardizing lumber quality (in comparison with the two weeks that is currently required in conventional kilns), and the percentage of pieces that remained wet after drying was within the 10% to 15% range that is typically tolerated in industry.

  • 253.
    Elustondo, Diego
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sundqvist, Bror
    SP Technical Research Institute of Sweden.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Localized Wood Surface Modification: Part I: Method Characterization2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 1, p. 283-295Article in journal (Refereed)
    Abstract [en]

    This study assesses the potential of an open process for treatment of European Scots pine (Pinus sylvestris) with chemicals that could potentially make the surfaces stronger, more dimensionally stable, or more durable, depending on the treatment solution. The method provides an intermediate solution between full volume impregnation by pressure treatment and superficial surface treatment by dipping. Figuratively speaking, the process creates the equivalent of a layer of coating applied below the wood surfaces rather than above. Two different techniques were compared, namely, heating-and-cooling (H&C) and compression-and-expansion (C&E). Taking into account that commercial suppliers recommend 0.15 to 0.25 L/m2 of coating in sawn wood and 0.1 to 0.15 L/m2 in planed wood surfaces, then this study demonstrates that the H&C method can impregnate an equivalent amount of solution under the surfaces in less than 15 min using treatment temperatures below 150 °C.

  • 254.
    Elustondo, Diego
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sidorova, Ekaterina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Development of method for surface modification of wood.2015In: Proceedings of the Eighth European Conference on Wood Modification: ECWM8 / [ed] Mark Huges; Lauri Rautkari; Tuuli Uimonen; Holger Militz; Brigitte Junge, Helsinki: Aalto University, School of Chemical Engineering , 2015, p. 137-140Conference paper (Refereed)
  • 255.
    Elustondo, Diego
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Örberg, Håkan
    Swedish University of Agricultural Sciences.
    Xiong, Shaojun
    SLU, Umeå, Swedish University of Agricultural Sciences, Umeå.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Measuring moisture content and shrinkage during drying of biological materials through CT-scanner technology.2015In: Proceedings of the 5th European Drying Conference (EuroDrying’2015), Budapest: Szent István University, Gödöllő , 2015, p. 113-119Conference paper (Refereed)
  • 256. Eriksson, John
    et al.
    Johansson, Håkan
    Danvind, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    A mass-transport model for drying wood under isothermal conditions2005In: Proceedings: 9th International IUFRO Wood Drying Conference, Nanjing Forestry University , 2005Conference paper (Refereed)
  • 257.
    Eriksson, John
    et al.
    Chalmers University of Technology.
    Johansson, Håkan
    Danvind, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Numerical determination of diffusion coefficients in wood using data from CT-scanning2006In: Wood and Fiber Science, ISSN 0735-6161, Vol. 38, no 2, p. 334-344Article in journal (Refereed)
    Abstract [en]

    The radial moisture diffusion coefficient in Fick's law for a sample of Norway spruce (Picea abies) under isothermal drying conditions was determined in a parameterization of Arrhenius' equation type. Using X-ray CT-scanning, the wood density and moisture content distributions were obtained in the radial direction for the wood sample. An optimization scheme, based on finite element computation, was then applied to find the parameter values such that the difference between observed and computed moisture content was minimized. The combined numerical and experimental technique was developed to reduce known disadvantages of similar approaches, and a specific algorithm to determine diffusion coefficients was presented. A comparison of the calibrated diffusion coefficient with those given in the literature showed a good fit. The computed moisture content based on the obtained diffusion coefficient and the observed moisture content agreed well. Finally, the effect of measurement errors on the computed material parameter was found to be small

  • 258. Esping, Björn
    et al.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Program för svensk trätorkningsforskning 1983-19861983Report (Other academic)
  • 259. Esping, Björn
    et al.
    Morén, Tom
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Program för svensk trätorkningsforskning 1983-19861983Report (Other academic)
  • 260.
    Flodin, Jens
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    On fingerprint traceability in the forestry supply chain2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Tracing material through the forestry supply chain is a relatively untapped source for process and product improvements. Since the supply chain handles large quantities at high speeds, have a diverging flow and several different sub processes and people involved along the way, traceability rapidly becomes very complex. The papers presented in this thesis have been focused on tracing wood material by means of the fingerprint approach. The fingerprint approach rests on the foundation that each piece of wood is a unique individual with unique features and that it would be possible to identify and connect individual pieces in the supply chain in the same way that human beings can be identified by the use of their fingerprints. The results from paper I show the importance of preserving the shape of the log and handling the bark assessment at an individual level when trying to connect logs between the log sorting station and saw intake using their 3D outer shape. Paper II and paper III show very encouraging results in connecting sawn timber to the log they were sawn from by using 3D and x-ray data for the logs and surface scanning for the sawn timber. The results show that over 95 % of the sawn timber could be connected to the correct log.

  • 261. Flodin, Jens
    et al.
    Oja, Johan
    Grönlund, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Fingerprint traceability of logs using the outer shape and the tracheid effect2008In: Forest products journal, ISSN 0015-7473, Vol. 58, no 4, p. 21-27Article in journal (Refereed)
    Abstract [en]

    Traceability in the sawmilling industry is a concept that, among other benefits, could be used to more effectively control and pinpoint errors in the production process. The fingerprint approach is a traceability concept that in earlier studies has shown good potential for tracing logs between the log sorting station and the saw intake. In these studies, bark has been identified as a large source of measurement inaccuracy. This study was set out to investigate whether the fingerprint recognition rate could be improved when compensating for bark with traditional bark functions or a new automatic bark assessment based on the tracheid effect. The results show that the fingerprint recognition rate can be improved by using more sophisticated bark compensation. Compared to no bark compensation, improvements can be made by using the existing bark functions, and even further improvements can be made by using automatic bark assessment based on the tracheid effect. The results further show that the butt-end reducer between the log sorting station and the saw intake has a very negative effect on the fingerprint recognition rate, but that significant improvements in the recognition rate can be achieved by excluding the section of the log's butt end that is affected by the butt-end reduction.

  • 262. Flodin, Jens
    et al.
    Oja, Johan
    Grönlund, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Fingerprint traceability of sawn products using industrial measurement systems for x-ray log scanning and sawn timber surface scanning2008In: Forest products journal, ISSN 0015-7473, Vol. 58, no 11, p. 100-105Article in journal (Refereed)
    Abstract [en]

    Traceability in the sawmilling industry is a concept that, for example, could be used to more effectively control the production process and the utilization of raw material. The fingerprint approach is a traceability concept that rests on the principle that every piece of wood is a unique individual with unique properties and therefore can be identified and separated if a sufficient number of these properties are measured accurately enough. This study was made with the aim of making the fingerprint connection between logs and the center yield sawn from those logs using length and knot information. The material used was Scots pine logs from six different diameter groups sawn with a two-ex sawing pattern into six different dimensions of center-yield planks. The data from the logs were collected at the log sorting station by an industrial one-directional x-ray log scanner in combination with a 3-D optical scanner. The data from the sawn center yield were collected by an industrial cross-fed surface scanning system situated in the sawmill's green sorting station. The results show that over 95 percent of all planks could be matched to the right log. This gives a high potential for further development and realization of fingerprint tracing between the log sorting and the green sorting station into a practical application for process control and process improvement.

  • 263. Flodin, Jens
    et al.
    Oja, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Grönlund, Anders
    Fingerprint traceability of sawn products using x-ray logscanning and sawn timber surface scanning2007In: Quality control for wood and wood products: COST Action E 53 the first conference, October 15th/17th, 2007, Warsaw, Poland / [ed] Marek Grześkiewicz, Warsaw: Warsaw University of Life Sciences , 2007, p. 39-42Conference paper (Refereed)
    Abstract [en]

    Traceability in the sawmilling industry is a concept that could be used to more effectively control the production processand the utilization of the raw material. The fingerprint approach is a traceability concept that rests on the idea that everypiece of wood is a unique individual with unique properties and hence can be identified and separated if a sufficientnumber of these properties are measured accurately enough. This study was hosted by a sawmill in northern Sweden andwas aimed at making the fingerprint connection between logs and the center yield sawn from those logs using length andknot information. The 140 logs involved in the study were of Scots pine with top diameters spanning the range from 153 to213 millimeters. The center yield sawn from these logs was of two dimensions. The smaller logs (153-187 mm) were sawnwith a 2 ex pattern to 50 by 100 mm, and the larger logs (174-213 mm) were sawn to 50 by 125 mm with a 2 ex pattern.The data from the logs were collected at the log sorting station by an industrial one-directional x-ray log scanner incombination with a 3-D optical scanner. The data from the sawn center yield were collected by an industrial cross-fedsurface scanning system situated in the sawmill's green sorting station. Both systems are used in the sawmill's normalcontinuous production. The results show that over 90% of all planks could be matched to the right log, which bespeaksa great potential for further development and realization of fingerprint tracing as a tool for process control and processimprovement.

  • 264.
    Forsman, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Real-World Three-Dimensional Measuring of Built Environment with a Portable Wire-Based Coordinate-Measuring Machine2015In: Forest products journal, ISSN 0015-7473, Vol. 65, no 5-6, p. 247-262Article in journal (Refereed)
    Abstract [en]

    A long-term strategy within the forest products industries is to increase the products' refinement and thus their value. This strategy applies to both primary and secondary processed wood products. Further down the value stream, different kinds of knowledge are needed in order to add value and efficiency in the supplier process. In this study, the focus was on as-built three-dimensional (3-D) sensing as a means to increase the level of product prefabrication when supplying engineer-to-order joinery products to the construction industry. A 7-m ranging three-axis portable wire-based coordinate-measuring machine (PWCMM) was evaluated in terms of performing as-built site-dimensional verification in 3-D. This is a needed means for moving the fitting of joinery products into the digital domain at the design stage, thus increasing the level of prefabrication and automation possible when supplying engineer-to-order joinery products. The PWCMM has been used to replicate different construction sites to gain as-built spatial information as input into the suppliers' design, manufacturing, and on-site assembly processes. The evaluation shows that the accuracy in each coordinate position can be within a millimeter range. However, questions still remain about the capability to meet the demands on accuracy and usability for on-site dimensional verification when supplying joinery products. Issues with error leverage and low measurement resolution limit the practical possibilities in terms of level of accuracy and detail of the reproduction of the as-built environment.

  • 265.
    Forsman, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Suggestions for innovation in the supplying of joinery products through the application of Lean-thinking and 3-D sensing2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The supplying of engineer-to-order joinery products to the construction industry is a novel research area in both the wood-related and the construction-related fields. The process of supplying the construction industry with highly refined one-of-a-kind wood products is here examined in order to explore possible process innovations to identify factors contributing to inefficiency, to define areas for innovation to improve industry performance, and to evaluate 3-D sensing technologies as a way of achieving a model-based joinery production. The organizations studied use a mixture of concept-to-order and design-to-order production strategies to produce what in this thesis are called engineer-to-order joinery products.The main consumer of the engineer-to-order joinery products are theconstruction industry, an industry that has been criticized for not keeping upwith other production industries in terms of quality, cost efficiency, innovation,and production methods. The development of Lean production principles andsupply chain management are innovations commonly suggested to increase the degree of industrialization in the construction industry, and this is reflected in the research approach adopted for the work described in this thesis. The conditions for supplying engineer-to-order joinery products to theconstruction industry have been studied and areas for innovation efforts aresuggested. The primary research question has been: Can new technology and new management methods be applied to improve process efficiency and efficacy in the supplying of engineer-to-order joinery products? Lean principles and 3-D sensing are two perspectives chosen to investigate this supply process. The study has used both qualitative and quantitative research methods, with a slight overweight towards the qualitative methods, as the context for the quantitative research has always been in focus. Real-world case studies have been used for the empirical data collection.The results suggest that there is a significant potential for increasing efficiency and efficacy through: greater focus on cross-organisational innovation focusing on higher levels of industrialisation, new forms of contractual relations, supply chain cooperation, improved knowledge-transfer and information management, developing competence on 3-D sensing and “BIM”-modelling, and through organisational consolidation.

  • 266.
    Forsman, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Supplying engineer-to-order joinery products to the construction Industry2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The supplying of engineer-to-order joinery products to the construction industryis considered a novel research area in the wood-related literature as well as in theconstruction-related literature. The process of supplying the construction industrywith highly refined one-of-a-kind wood products is examined in this thesis, andmore specifically, an organization using a mixture of concept-to-order and designto-order production strategies to produce Engineer-to-order Joinery Products. Thefocus in this work is on the possibilities for innovation in the industry of supplyingengineer-to-order joinery products and on improved integration with theconstruction industry.The construction industry has been criticized for not keeping up with otherproduction industries in terms of quality, cost efficiency, innovation, andproduction methods. The development of Lean production principles and supplychain management are innovations commonly suggested as improvements inincreasing the degree of industrialization to the construction industry, and this isalso reflected in this work where waste in the process has been identified.The work is weighted towards a qualitative research approach, and real-world casestudies have been used for the empirical data collection.Results from the studied cases indicate that the process of supplying engineer-toorderjoinery products to construction has the potential for improved efficiency.Violations of Lean principles are identified, and these have effects on the process ofsupplying joinery products to construction. Much of the identified waste can findits cause in these violations. Innovation in adopting Lean principles and managinginformation, supply chain, planning, and coordination is believed to be essential forimproving total process performance in supplying engineer-to-order joineryproducts to construction.The supplying of engineer-to-order joinery products faces opportunities andchallenges similar to those in the industrialized housing industry. An increased levelof prefabrication, decreased assembly time, and increased predictability of on-sitework seem possible if confronting the root causes found in this work.

  • 267.
    Forsman, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Björngrim, Niclas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Bystedt, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Laitila, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Bomark, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Öhman, Micael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Need for innovation in supplying engineer-to-order joinery products to construction: a case study in Sweden2012In: Construction Innovation, ISSN 1471-4175, E-ISSN 1477-0857, Vol. 12, no 4, p. 464-491Article in journal (Refereed)
    Abstract [en]

    Purpose – The construction industry has been criticized for not keeping up with other production industries in terms of cost efficiency, innovation, and production methods. The purpose of this paper is to contribute to the knowledge about what hampers efficiency in supplying engineer-to-order (ETO) joinery-products to the construction process. The objective is to identify the main contributors to inefficiency and to define areas for innovation in improving this industry. Design/methodology/approach – Case studies of the supply chain of a Swedish ETO joinery-products supplier are carried out, and observations, semi-structured interviews, and documents from these cases are analysed from an efficiency improvement perspective. Findings – From a lean thinking and information modelling perspective, longer-term procurement relations and efficient communication of information are the main areas of innovation for enhancing the efficiency of supplying ETO joinery-products. It seems to be possible to make improvements in planning and coordination, assembly information, and spatial measuring through information modelling and spatial scanning technology. This is likely to result in an increased level of prefabrication, decreased assembly time, and increased predictability of on-site work. Originality/value – The role of supplying ETO joinery-products is a novel research area in construction. There is a need to develop each segment of the manufacturing industry supplying construction and this paper contributes to the collective knowledge in this area. The focus is on the possibilities for innovation in the ETO joinery-products industry and on its improved integration in the construction industry value chain in general.

  • 268.
    Forsman, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Bystedt, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Öhman, Micael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Interaction in the construction process: System effects for a joinery-products supplier2011In: Lean Construction Journal, ISSN 1555-1369, E-ISSN 1555-1369, Vol. 2011, p. 1-18Article in journal (Refereed)
    Abstract [sv]

    Denna fallstudie beskriver svagheter i den samverkan som sker i byggprocessen vid upphandling av specialsnickerier. Resultaten visar på att informationen i processen är bristfällig och att dess överföring inte är säkrad. Kompetens att förädla och modellera information behöver utökas. En stor del av tiden tillförs inget värde till produkten vilket försvårar kommunikationen i värdekedjan vilket påverkar produktens kvalité. Mycket av problemen kan undvikas genom ökad interaktion mellan leverantören, föreskrivande arkitekter, och angränsande processer. En ökad grad av standardisering för samverkan och informationsutbyte, samt att minska systemberoende buffertlager för att öka andelen tid för värdeskapande aktiviteter, är andra förbittrare av prestanda i denna process.

  • 269.
    Forsman, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Laitila, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Applicability of as-built 3-D sensing technologies for improved efficiency when supplying joinery products2016In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280Article in journal (Refereed)
    Abstract [en]

    With currently used surveying methods, the on-site assembly of joinery products often consumes half the supplier budget. Due to spatial uncertainties, the manual product-to-room fitting of components is a major consumer of time and labour resources. With reliable as-built construction site geometrical information, this fitting could be moved to the design stage early in the supplier process. In this study, the currently used manual surveying methods were compared with two different 3-D sensing surveying methods, a portable wire-bound coordinate measuring machine (CMM) and a laser-scanning machine. The comparison evaluates the applicability of the on-site surveying methods and their potential for improving the current surveying process, moving the product-to-room fitting to the design stage. Results show that currently used manual surveying methods leave uncertainties regarding the dimensions of a construction site and are insufficient for moving the product-to-room fitting to the design stage. CMM surveying has the potential to supply coordinate registrations on a par with desired accuracy requirements, but it has limitations at the practically possible detailing level. Laser scanning seems to be applicable for the surveying for a joinery products supplier, but the accurate and detailed 3-D reconstruction of the point cloud data is difficult and requires extensive processing. It can be concluded that the concept of digitized measurement of the as-built spatial dimensions of a construction site to enable product-to-room during the design stage has the potential to succeed with currently available digitizing technologies, but that some challenges remain.

  • 270.
    Forsman, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Laitila, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Three-dimensional, as-built site verification in supplying engineer-to-order joinery products to construction2015In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, no 4, p. 353-367Article in journal (Refereed)
    Abstract [en]

    With currently used surveying methods, the on-site assembly of joinery products often consumes half the supplier budget. Due to spatial uncertainties, the manual product-to-room fitting of components is a major consumer of time and labour resources. With reliable as-built construction-site geometrical information, this fitting could be moved to the design stage early in the supplier process. In this study, the currently used manual surveying methods were compared with two different three-dimensional (3-D) sensing surveying methods, a portable wire-bound coordinate measuring machine (CMM) and a laser-scanning machine. The comparison evaluates the applicability of the on-site surveying methods and their potential for improving the current surveying process, moving the product-to-room fitting to the design stage. Results show that currently used manual surveying methods leave uncertainties regarding the dimensions of a construction site and are insufficient for moving the product-to-room fitting to the design stage. CMM surveying has the potential to supply coordinate registrations on a par with desired accuracy requirements, but it has limitations at the practically possible detailing level. Laser scanning seems to be applicable for the surveying for a joinery products supplier, but the accurate and detailed 3-D reconstruction of the point-cloud data is difficult and requires extensive processing. It can be concluded that the concept of digitized measurement of the as-built spatial dimensions of a construction site to enable product-to-room during the design stage has the potential to succeed with currently available digitizing technologies, but that some challenges remain

  • 271.
    Forsman, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Laitila, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Björngrim, Niclas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    3-D measuring for an engineer-to-order secondary wood processing industry2012In: World Conference on Timber Engineering, WCTE: Final Papers - Poster presentations / [ed] Pierre Quenneville, New Zealand Timber Design Society , 2012, p. 498-504Conference paper (Refereed)
  • 272.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    A simulation tool for the finger jointing of boards2011Conference paper (Refereed)
    Abstract [en]

    Knowledge about how tree properties affect the final product is necessary to utilise each log and tree in the forestry production chain fully. So far, the Swedish Pine Stem Bank (SPSB) has been used extensively for sawing simulation, but not for simulation further down the production process. Hence, it is desirable to model the further processing of sawn timber using the SPSB. In this study, a simulation tool for cross cutting and finger jointing of boards has been developed and tested. The simulation program utilises the SPSB and the results from a sawmill simulation program to simulate a cross-cutting and finger-jointing process. The tool has been tested against an empirical material consisting of defect data from an industrial scanner, used at a producer of finger-jointed furniture products. To illustrate the potential use of the finger-jointing simulation program, two investigations have also been carried out. The first deals with comparing the recovery for finger jointing and cutting of solid boards for different products. The second investigation is an attempt to estimate the impact of process-related defects on the recovery of finger-jointed products. The results show that the simulation tool produces similar results as the real process, and the use of the SPSB provides adequate predictions of the real system’s behaviour. The first of the investigations shows that finger jointing generally has a better recovery than cutting of solid boards, but for short products, the latter might be a viable option. The second investigation suggests that process-related defects reduce recovery by up to 5% units in the finger-joint process studied. Thus, there is future potential for using the finger-jointing simulation tool to investigate production strategies and/or raw material selection in the forestry production chain.

  • 273.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Computer simulation in the forestry-wood chain2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The forestry-wood chain today involves many actors, and the decisions taken in the process of making trees into finished products are so many that the effect of each individual decision is difficult to assess, especially if the natural variation of the input material is considered.This means that a simulation approach to the forestry-wood chain is suitable, since it makes it possible to evaluate the effects of decisions in a short timeframe, while the input material can be kept constant for different production setups. The long term aim is to connect tree and log properties to the quality of a final product through simulation, depending on the various operations involved in making the product.A part of this is realized through this thesis. It is shown that a simulation model of a cross-cutting and finger-jointing process is representative of a real process. The model is used to evaluate an adaptive strategy for setting the safety zone size between finger-joints and sound knots, a strategy which improves recovery in a finger-jointing operation by 3 %.Another issue addressed in this thesis is that of simulation input data. The sawing simulation tool used to a large extent in research today, Saw2003, usesthe Swedish Pine Stem Bank as input data. This is a very well-documented datasource, and computed tomography (CT) scanning of the stem bank logs allows wood features such as knots to be represented in a realistic way in Saw2003. There are limitations to the stem bank, however, mostly due to the fact that CT scanning is a time consuming process, which means that the amount of scanned logs is relatively small. In this thesis, it is shown that it is possible to use a small amount of log features for determining the knot structure in a log, which opens up possibilities for using industrial data from two-directional X-ray scanners. This would increase the amount of logs to be used as simulation input data.A second set of data used for simulation was also collected in a study of a production process, where the wood raw material was followed from the logyard through all production operations of making finger-jointed furniture components. Each individual piece of wood was traced through the operations, thus ensuring a link between the properties of logs and those of the finished product. This second data set was collected by grey-scale camera scanning of boards prior to cross-cutting and finger-jointing, and was used in the development of cross-cutting and finger-jointing simulation. It contains information on non-clearwood features of the board surfaces such as knots, cracks, and pitch pockets.It can be concluded from this thesis that it is possible to increase bothfunctionality and the amount of input data in the simulation of the forestry-wood chain, and by doing so production strategies and decisions can be evaluated. Wood quality discussions may be simplified by being able to assess the effects on the production process of decisions being made. Future work involves adding more functionality to the simulation environment as well as evaluating the methods proposed in this thesis industrially. The long term vision is to be able to integrate the forestry-wood chain from log to finished product in one simulation model.

  • 274.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Handling positioning errors when optimizing sawing of Scots pine and Norway spruce logs using CT scanning2016In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 62, no 5, p. 400-406Article in journal (Refereed)
    Abstract [en]

    Since computed tomography (CT) X-ray scanning is becoming a reality in sawmills, different studies have been made to establish how well the sawing position of a log can be optimized using CT data. It is also known that positioning errors have an adverse effect on optimization, since the optimization methods used are rather sensitive to positioning errors. To mitigate the effect of positioning errors, a method is proposed in this article that filters results produced by sawing simulation, using a Gaussian filter of a size according to the positioning error. Using these filtered values for optimization, it is possible to retain two percent extra value of the sawn timber, when rotation and offset errors are present, compared to a regular optimization method. A method more robust to positioning errors is more useful in practice, since positioning errors of various magnitudes are always present in sawmills. The main contribution of this paper is, therefore, an optimization method that reduces the effect of positioning errors.

  • 275.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Log Positioning by Aid of Computed Tomography Data and Sawing Simulation2013Conference paper (Refereed)
  • 276.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Log Sawing Position Optimization using Computed Tomography Scanning2014In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 9, no 2, p. 110-119Article in journal (Refereed)
    Abstract [en]

    When disjoining a log, several factors affect the value of the sawn timber. There are log features, such as outer shape, knots, rot, and so on. There are also sawing parameters, such as sawing pattern, log position, and so on. If full information about log features is available, sawing parameters can be adapted in order to maximize product value in sawmills. This is soon possible, since computed tomography (CT) scanners for the sawmill industry are being realized. This study aimed at investigating how CT data can be used to choose rotational position, parallel displacement, and skew of sawlogs, to maximize the value of the sawn products. The study was made by sawing simulation of 269 CT scanned logs of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] H. Karst.). The results showed that value recovery could be improved by 13% in average, compared to a sawing position based on log outer shape, and 21% compared to sawing logs centered and horns down. It can be concluded that a CT scanner, used in a sawline to optimize sawing parameters, has a large potential for increasing value recovery and thus profit.

  • 277.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Optimizing sawing of boards for furniture production using CT scanning technique2015In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 61, no 5, p. 474-480Article in journal (Refereed)
    Abstract [en]

    The inherent variability of wood material together with sub-optimization in production processes means that a lot of potential value is lost. Computed tomography scanning together with simulation models of the production processes could remedy this, and ensure optimization of the entire production process. Therefore, the purpose of this study was to investigate if such methods can be used to optimize the sawing position of logs in a production process including further processing, in this case crosscutting to make a furniture product with strict quality requirements on dead knots. This was done on 47 Scots pine (Pinus sylvestris L.) logs. The results show a potential yield increase of more than 11 % points in the crosscutting operation and more than 4 % points when viewing the process as a whole, compared to sawing the logs horns down and centered

  • 278.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Reconstruction of Pinus Sylvestris knots using measurable log features in the Swedish Pine Stem Bank2012In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 27, no 5, p. 481-491Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to develop a method for reconstruction of parametrically described whorls and knots from data possible to extract from industrial scanning of logs, using X-ray scanners. The method was conceived using the logs in the Swedish Pine Stem Bank as a foundation, and was based on a few predictor features extracted from these logs; namely whorl volume, distance between whorls and distance between pith and surface. These features were not measured in images but calculated from existing parameterised knots. Simulated test sawing shows that the reconstruction method results in a representative model of the knot structure in the log, when considering the grade distribution of the sawn timber produced by the simulation program. The results of this study could, for instance, be used for improved online quality predictions at sawmills. One step in this direction is to use industrial X-ray data to enlarge the amount of log data available for sawing simulation research. Future work can, therefore, focus on developing a practical application of the results presented here.

  • 279.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    The Value of Wood: Production Strategies in the Forestry-Wood Chain Using X-ray Scanning and Computer Simulation2014Doctoral thesis, comprehensive summary (Other academic)
  • 280.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Using a Gaussian filter to reduce the effect of positioning errors when optimizing sawing of CT scanned Scots pine and Norway spruce logs2017In: International Wood Machining Seminar (IWMS-23), 2017Conference paper (Refereed)
    Abstract [en]

    Computed tomography (CT) scanning of logs is being introduced in sawmills, so there is reason to study how log positioning can be controlled using information from CT. However, positioning errors affect this positioning optimization in a negative way. To reduce this effect, a method was developed using sawing simulation, where logs were sawn in a large number of positions, varying rotation and centering. This resulted in three-dimensional surfaces, with the sawn timber value, rotation and centering on the axes. The surfaces were filtered with a Gaussian filter using a distribution corresponding to that of the positioning error. The filtered values were used for optimization, choosing the global maximum. This resulted in a value recovery that was about two percent higher compared to a simpler optimization without filtering, for a normally distributed rotational error of 5 – 15° standard deviation and a ditto centering error of 3.5 – 10.5 mm standard deviation. This was tested using sawing simulation, using the optimal log position for the two methods, with an added positioning error. Furthermore, the robust method has been tested on a smaller number of rotational positions, starting from horns down, to reduce the number of necessary calculations. The result of this was that at least ± 60 ° in the rotational direction should be evaluated for the robust method to result in a higher recovery than the simpler optimization. The robust method was better than sawing horns down and centered, no matter the positioning error, using only 65 evaluated positions per log.

  • 281.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Berglund, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Broman, Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Validating a crosscutting simulation program based on computed tomography scanning of logs2015In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 73, no 2, p. 143-150Article in journal (Refereed)
    Abstract [en]

    Wood scanners and software for calculating crosscutting positions have been used in the wood industry for some years now. The scanners are used to detect biological and geometrical deviations on the sawn timber, which makes it possible to remove undesired defects using crosscut saws. Yield calculations for crosscutting have not been investigated to the same extent as sawing yield calculations for primary breakdown of logs, especially if the whole chain from log to end product is considered. The objective of this study was to validate the result of a computer program developed for simulating crosscutting of boards. The crosscut simulations were performed with respect to knot characteristics on Scots pine (Pinus sylvestris L.) board surfaces. Validating a crosscutting simulation program would mean that it can be used to investigate how raw material and customization of quality rules affect the yield in a wood production chain from log to crosscut end product. The validation showed that crosscutting yield for boards could be predicted with a root mean square error of 13 percentage points, and the technique can be used to identify unsuitable logs for a certain product at an early stage of production.

  • 282.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Bomark, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Broman, Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Grönlund, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    A trapeze edging method for cross laminated timber panel production2015In: Proceedings of the 22nd International Wood Machining Seminar / [ed] Roger Hernández; Claudia Cáceres, Quebec city, Kanada: Universite Laval , 2015, p. 323-332Conference paper (Refereed)
  • 283.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Bomark, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Broman, Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Grönlund, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Using Small Diameter Logs for Cross Laminated Timber Production2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 1, p. 1477-1486Article in journal (Refereed)
    Abstract [en]

    Sawing small diameter logs results in lower yield compared to sawing large diameter logs. This is due to geometry; fitting rectangular blocks inside an approximately cylindrical shape is more difficult for small than for large diameters. If small diameter logs were sawn in a way that follows the outer shape, yield would increase. The present study considers whether this can be done by sawing flitches into trapeze shapes. These can be glued together into rectangular products. Cross laminated timber (CLT) products are suitable for this. The study was based on 4,860 softwood logs that where scanned, and the scanning data was used for sawing simulation. The log top diameters ranged from 92 to 434 mm. The volume yield of CLT production using trapeze edging was compared to cant sawing of boards. The trapeze edging and CLT production process improved yield compared to cant sawing by 17.4 percent units, for logs of a top diameter smaller than 185 mm. For all logs, the yield decreased using the trapeze edging method. To conclude, a trapeze edging method shows promise in terms of increasing volume yield for small diameter logs, if boards can be properly taken care of in a CLT production process

  • 284.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Broman, Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Factors Affecting Volume Yield in a Forestry-Wood Value Chain: A Simulation Study Based on CT Scanning2017In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, no 4, p. 540-548Article in journal (Refereed)
    Abstract [en]

    The paper presents the results of a simulation study, where log models based on CT scanned logs of Scots pine (Pinus sylvestris L.) was used as input material to a computer simulation model of a generic value chain involving sawing, drying, crosscutting and finger jointing. The aim was to investigate which factors that affect the volume yield in the value chain, be it forestal, log-, process- or quality-related factors. The results show that factors related to growth conditions and log size have a large impact on the volume yield in the studied value chain, together with quality requirements on knots. Factors such as sawing positioning and log quality had a much smaller impact. It can be concluded that it is possible to model a forestry-wood value chain, while assessing which input variables affect the result in terms of volume yield, using CT scanning of logs and subsequent computer simulation of the production processes.

  • 285.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Broman, Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Persson, Fredrik
    SP Trä.
    Axelsson, Ann
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ah Shenga, Pedro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Rotational Position of Curved Saw Logs and Warp of the Sawn Timber2014In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 9, no 1, p. 31-39Article in journal (Refereed)
    Abstract [en]

    With the development of scanning technology in sawmills, it is possible to optimise log rotational position when sawing. However, choosing a different rotational position than horns down might be detrimental for the board shape after drying, especially for curved logs. Thus, there is a need to investigate at what level of log curve it is possible to freely rotate logs without causing board warp. This study was carried out through a test sawing that was conducted at a sawmill situated in the middle of Sweden. The tests were made on 177 Norway spruce logs, with varying amount of curve. Half of the logs were sawn in the horns-down position, half were sawn rotated perpendicular to horns down. Log shape and warp of the dried boards were measured. The results indicated a relationship between board spring, log curve and choice of rotational position. Furthermore, board bow was related to log curve but not rotational position. It can be concluded that for straight logs, with a bow height of less than 15 mm, an unconventional rotational position does not cause excess spring in the boards. Bow and twist are not affected by the rotational position at all.

  • 286.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Broman, Olof
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    The Use of CT-Scanning Technology in Wood Value-Chain Research and in Wood Industry: A State of The Art2017In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, no 4, p. 533-539Article in journal (Refereed)
    Abstract [en]

    X-ray computed tomography (CT) is a powerful tool for the non-destructive  measurement  of  dynamic  processes in wood. After more than 25 years of research at Luleå University of Technology in the field of CT-scanning of wood material, the first industrial CT-scanners are now installed in sawmill production for the in-situ measurement of internal  log features to steer of the sawmill process with the help of this information.This  paper  provides  an  overview  of  the  potential  of  CT-scanning in wood-material  research  and  how  this data can be used for the modelling and simulation of the wood value chain. A database of CT-images of trees  is  used  to  create  a  log  model  including  the  outer  shape  of  the  logs  and  their  internal  knot  structure.  Simulation software is used to saw these virtual logs in different positions relative to the sawblade, and also for the crosscutting of the sawn timber to components. The output is dimensions and grades of sawn timber, volume yield as well as an economic result based on real economic conditions. A specially designed climate chamber  for  CT  studies  of  the  drying  of  sawn  timber  is  used  to  increase  the  knowledge  of  how  the  drying  affects the response from the sawn timber during seasoning.

  • 287.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Brännström, Mattias
    Technical solutions to increase competitiveness of cross-laminated timber from the Nordic countries: an overview2018Conference paper (Refereed)
  • 288.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cool, Julie
    University of British Columbia.
    Avramidis, Stavros
    University of British Columbia.
    Knot detection in computed tomography images of partially dried Jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) logs2017In: International Wood Machining Seminar (IWMS-23), 2017Conference paper (Refereed)
    Abstract [en]

    X-ray computed tomography (CT) of logs means possibilities for optimizing breakdown in sawmills. This depends on accurate detection of knots to assess internal quality. However, as logs are stored in the log yard they dry to a certain extent, and this drying affects the density variation in the log, and therefore the X-ray images. For this reason, it is hypothetically difficult to detect log features in partially dried logs using X-ray CT. The objective of this research was to investigate the effect of drying on knot detection in Jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) logs from New Brunswick, Canada. An automatic knot detection algorithm was compared to manual measurements for this purpose, and the results show that knot detection was clearly affected by partial drying. Because dried heartwood and sapwood have similar densities, the algorithm had difficulties detecting the heartwood-sapwood border. Based on how well the heartwood-sapwood border was detected, it was statistically possible to sort logs into two groups: 1) Low knot detection rate, and 2) High knot detection rate. In that way, a decision can be made whether or not to trust the knot models obtained from CT scanning. Therefore, logs that are partially dried out and fall in the low knot detection rate should be handled cautiously because the optimization results based on CT knot detection cannot be fully trusted. Sawing of these logs could be optimized using only their outer shape, ignoring internal quality. Similarly, only logs having a regular heartwood shape should be used when scanning logs for research purposes or in databases of CT scanned logs. Finally, a larger knot detection rate was obtained for Jack pine. This could have been facilitated by the fact that pine trees usually have larger but less numerous knots than spruce trees.

  • 289.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cool, Julie
    University of British Columbia, Vancouver .
    Duchesne, Isabelle
    Natural Resources Canada, Canadian Wood Fibre Centre, Québec, Canada.
    Belley, Denis
    Ministère des Forêts, de la Faune et des Parcs, Québec, Canada.
    Knot detection in computed tomography images of partially dried Jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) logs from a Nelder type plantation2017In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 47, no 7, p. 910-915Article in journal (Refereed)
    Abstract [en]

    X-ray computed tomography (CT) of logs means possibilities for optimizing breakdown in sawmills. This depends on accurate detection of knots to assess internal quality. However, as logs are stored they dry to some extent, and this drying affects the density variation in the log, and therefore the X-ray images. For this reason it is hypothetically difficult to detect log features in partially dried logs using X-ray CT. This paper investigates the effect of improper heartwood-sapwood border detection, possibly due to partial drying, on knot detection in jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) logs from New Brunswick, Canada. An automatic knot detection algorithm was compared to manual reference knot measurements, and the results showed that knot detection was affected by detected heartwood shape. It was also shown that logs can be sorted into two groups based on how well the heartwood-sapwood border is detected, to separate logs with a high knot detection rate from those with a low detection rate. In that way, a decision can be made whether or not to trust the knot models obtained from CT scanning. This can potentially aid both sawmills and researchers working with log models based on CT.

  • 290.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Grönlund, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Fingerjointing simulation: first step to complete integration2011In: F D M Asia, ISSN 0218-7663, no Oct, p. 34-37Article in journal (Other (popular science, discussion, etc.))
  • 291.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Johansson, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Berglund, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Rotating Pinus sylvestris sawlogs by projecting knots from computed tomography images onto a plane2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 1, p. 816-827Article in journal (Refereed)
  • 292.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Skog, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Reconstruction of knots from simulated discrete x-ray images of Pinus Sylvestris logs2012Conference paper (Refereed)
    Abstract [en]

    For many years it has been of interest to be able to predict the properties of sawn wood products from tree features. X-ray technology has made it possible to measure internal as well as external features of saw logs, and to use these features for predicting log quality. However, data available for simulation of the sawing process and prediction of sawn timber quality has, until now, been limited to logs scanned using computed tomography.The objective of this study is to develop a method for reconstruction of parametrically described whorls and knots from industrial scanning of Scots pine (Pinus sylvestris L.) logs, using discrete Xray images. The method is designed using the logs in the Swedish pine stem bank (SPSB) as data basis, and is based on a few predictor features extracted from these logs, namely whorl volume, distance between whorls, and distance between pith and surface. These features are measured in simulated discrete X-ray images of the logs in the SPSB, and virtual models of the whorls and knots are created, using a feature- and knowledge based model. Virtual logs are then composed using the reconstructed knots within the original shape of the logs. Simulated test sawing of the virtual logs shows that the reconstruction method results in a representative model of the knot structure in the log, when considering the grade distribution of the sawn timber produced by the simulation program. The results of this study can for instance be used for improved online quality predictions at sawmills. One step in this direction is to use industrial X-ray data to enlarge the amount of log data available for sawing simulation research. Future work should focus on developing practical applications of the results presented here.

  • 293.
    Fredriksson, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Öhman, Micael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Song, Haitong
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Determination of crosscutting safety zone for finger-jointed Pinus sylvestris furniture components2012In: Forest products journal, ISSN 0015-7473, Vol. 62, no 2, p. 107-113Article in journal (Refereed)
    Abstract [en]

    A common problem with finger-jointed wooden furniture components is chipping in the finger joints due to fiber deviations around sound knots. To avoid this, a fixed size safety zone between defects and crosscuts is used, but can lead to an excess of material cut away in the crosscutting operation. To reduce chippings in finger joints while maximizing recovery, an adaptive strategy was developed for setting the safety zone size between sound knots and finger joints in Scots pine (Pinus sylvestris L.) furniture components. The strategy was based upon modeling the risk of chipping the finger joint depending on the knot measurement. The model was used in an adaptive strategy in order to minimize the expected loss due to cutting away material around knots, compared with the cost of rejecting components in later stages due to chipped finger joints. Thus, each knot was assigned a unique safety zone. The strategy was tested using computer simulation of the finger-jointing process, and a sensitivity analysis was performed in order to quantify the effect of variations in the input data. The results show that the adaptive strategy improves recovery by at least 3 percent in the process of turning lumber into finger-jointed furniture components. It is very robust toward variations in knot size measurements (e.g., by scanning equipment), but less robust toward variations in crosscutting precision.

  • 294.
    Fredriksson, Maria
    et al.
    Division of Building Materials, Lund University.
    Lindgren, Owe
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    End grain water absorption and redistribution in slow-grown and fast-grown Norway spruce (Picea abies (L.) Karst.) heartwood and sapwood2013In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, no 4, p. 245-252Article in journal (Refereed)
    Abstract [en]

    Wood is susceptible to decay by rot fungi if it is exposed to high-moisture contents during long periods of time and it is therefore important to limit the duration of such periods. Critical points in outdoor wood structures are, for example, end grain surfaces in joints where water can get trapped after a rain. It is therefore of interest to study both absorption and redistribution of moisture in wood. This paper presents moisture content profiles during end grain water absorption and redistribution in Norway spruce (Picea abies (L.) Karst.) measured by computed tomography with the specimens in individual climate boxes. Heartwood and sapwood of two provenances (slow-grown and fast-grown wood) were included. No major differences were seen between the water uptake of the slow-grown and the fast-grown wood since the densities were similar despite of the large difference in growth ring width. However, for the sapwood specimens, the moisture content was higher further into the specimens than for the heartwood specimens in agreement with previous studies. For the slow-grown wood, the redistribution was also generally more rapid for the sapwood specimens than for the heartwood specimens.

  • 295.
    Gaff, Milan
    et al.
    Czech University of Life Sciences Prague (CULS).
    Babiak, Marián
    Czech University of Life Sciences Prague (CULS).
    Kačík, František
    Czech University of Life Sciences Prague (CULS), Technical University in Zvolen.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Turčan, Marek
    Czech University of Life Sciences Prague (CULS).
    Hanzlíka, Peter
    Czech University of Life Sciences Prague (CULS).
    Vondrová, Veronika
    Czech University of Life Sciences Prague (CULS).
    Plasticity properties of thermally modified timber in bending: the effect of chemical changes during modification of European oak and Norway spruce.2019In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 165, p. 613-625Article in journal (Refereed)
    Abstract [en]

    The plasticity of thermally modified European oak (Quercus robur L.) and f thermally modified Norway spruce (Picea abies Karst. (L.)) timber was evaluated in bending, and the plastic properties were related to the changes in chemical composition of the wood after modification. The objective was to gain new knowledge about the properties of materials in the plastic region of the force-deformation diagram in bending. A new software was developed (MATESS) and used to identify important characteristics of the material. This software eliminates shortcomings in current standards, such as simplifications in the evaluation of data when sufficiently sensitive measuring equipment is not available. The characteristics studied were: modulus of rupture (MOR), plastic potential (PP) chord modulus (CHM), the moduli of plasticity (EE), and the moduli of plasticity (EMV, EP). Extractives, lignin, cellulose, holocellulose, and hemicelluloses were analysed chemically to reveal the patterns that occur during the loading of the specimens. Thermal modification has different effects on the mechanical properties of oak and spruce, especially on CHM, EMV and EP, due to their different contents and structures of their chemical components. A strong correlation (r > 0.90) between hemicellulose content and MOR and Pp values was found for both species. The coefficients of determination indicated a very low dependence (r2 < 0.1) of MOR, PP, CHM, EE, EMV and EP, on the average density.

  • 296.
    Gaff, Milan
    et al.
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic.
    Kačík, František
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic;Department of Chemistry and Chemical Technologies, Faculty of Wood Sciences and Technology, Technical University in Zvolen, Zvolen, Slovakia.
    Gašparík, Miroslav
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic.
    Todaro, Luigi
    School of Agricultural, Forestry, Food and Environmental Sciences, University of Basilicata, Potenza, Italy.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Corleto, Roberto
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic;School of Agricultural, Forestry, Food and Environmental Sciences, University of Basilicata, Potenza, Italy.
    Makovická Osvaldová, Linda
    Department of Fire Engineering, Faculty of Security Engineering, University of Žilina, Žilina, Slovakia.
    Čekovská, Hana
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic.
    The effect of synthetic and natural fire-retardants on burning and chemical characteristics of thermally modified teak (Tectona grandis L. f.) wood2019In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 200, p. 551-558Article in journal (Refereed)
    Abstract [en]

    This article deals with the effect of various temperatures of thermal modification and fire retardants on selected burning characteristics and chemical wood components of teak (Tectona grandis L. f.) wood. The thermal modification was carried out at temperatures 160 °C, 180 °C and 210 °C. Subsequently, thermally modified wood was treated by natural (arabinogalactan) and synthetic (ammonium phosphate) fire retardants. The effect of thermal modification as well as fire retardant was detected by burning characteristics such as weight loss, burning rate, maximum burning rate, ratio of the maximum burning rate and time to reach maximum burning rate. The chemical changes caused by the influence of these factors were determined by changing the content of cellulose, hemicelluloses, holocellulose, lignin and extractives. The relationship between burning characteristics and chemical changes in the thermally modified wood was analyzed using Spearman’s correlation. The results showed that the thermal modification of teak wood had a negative effect on its ignition and burning properties. Synthetic fire retardant had the highest retardation effect in all cases. The natural fire retardant caused a better retardation effect on thermally modified wood at temperature 180 and 210 °C. The relative content of lignin, extractives and cellulose increased, while the amount of holocellulose and particularly hemicelluloses decreased.

  • 297.
    Gaff, Milan
    et al.
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague,Suchdol, Czech Republic.
    Kačík, František
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague,Suchdol, Czech Republic.Department of Chemistry and Chemical Technologies, Faculty of Wood Sciences and Technology, Technical University in Zvolen, Zvolen, Slovakia.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague,Suchdol, Czech Republic.
    Babiak, Marián
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague,Suchdol, Czech Republic.
    Turčani, Marek
    Department of Forest Protection and Entomology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Suchdol, Czech Republic.
    Niemz, Peter
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague,Suchdol, Czech Republic.
    Hanzlík, Peter
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague,Suchdol, Czech Republic.
    The effect of chemical changes during thermal modification of European oak and Norway spruce on elasticity properties2019In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 220, p. 529-538Article in journal (Refereed)
    Abstract [en]

    The elasticity in bending of European oak (Quercus robur L.) and Norway spruce (Picea abies (L.) Karst.) timber was evaluated before and after thermal modificationand related to the changes in chemical composition of the wood as a result of the modification. A new software was developed (MATESS) and used to identify characteristic points on the force-deformation diagram. The modulus of elasticity(MOE), stress at the limit of proportionality (LOP) and elastic potential (PE) were used to describe the wood properties. Extractives, lignin, cellulose, holocellulose, and hemicelluloses were analysed to reveal the patterns that occur during the loading of the specimens. Thermal modification lowers the mechanical properties (MOE, LOP and PE) of oak and spruce wood, and the reduction increases with increasing modification temperature. Changes in chemical composition of thermally modified wood show a strong relationship to the reduction in elasticity properties for bot species.

  • 298.
    Garskaite, Edita
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Stankeviciute, Zivile
    bInstitute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania.
    Aivaras, Kareiva
    bInstitute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, Vilnius LT-03225, Lithuania.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Surface hardness and flammability of Na2SiO3 andnano-TiO2 reinforced wood composites.2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, p. 27973-27986Article in journal (Refereed)
  • 299.
    Garskaite, Edita
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Stankeviciute, Zivile
    Vilnius University.
    Kareiva, Aivaras
    Vilnius University.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Surface hardness and flammability of Na2SiO3 and nano-TiO2 reinforced wood compositesIn: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to explore an effect of the combined inorganic materials on the wood hardness and flame-retardancy properties in a concept of sustainable material management. Herein, the reinforcement of Scots pine (Pinus sylvestris L.) sapwood with sodium silicate and TiO2 nanoparticles via vacuum-pressure technique is reported. Pyrolysis of modified wood was studied by TG-FTIR analysis; the results showed that maximum weight loss for the modified wood was obtained at 40-50 °C lower temperatures compared to the reference untreated wood. The Gram-Schmidt profiles and spectra extracted at maxima absorption from Gram-Schmidt plots indicated chemical changes in wood-inorganic composites. SEM/EDS analysis revealed the presence of Na-O-Si solid gel within the wood-cell lumen and showed that TiO2 was homogeneously distributed within the amorphous Na-O-Si glass-forming phase to form a thin surface coating. EDS mapping further revealed the higher diffusivity of sodium into the cell wall compared to the silicon compound. The presence of amorphous sodium silicate and nano-TiO2 was additionally confirmed by XRD analysis. FTIR spectra confirmed the chemical changes in Scots pine sapwood induced by alkalization. Brinell hardness test showed that the hardness of the modified wood increased with the highest value (44% increase in hardness) obtained for 10% Na2SiO3-nTiO2 modified wood. The results showed good correlation between TG and flammability test; limiting oxygen index (LOI) values for the wood-inorganic composites increased by 9-14% compared to the untreated wood.

  • 300. Garzon, Alirio
    et al.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Future requirement for sustainable building envelope2018Conference paper (Refereed)
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