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  • 1.
    Ah Shenga, Pedro António
    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.
    External Log Scanning for Optimizing Primary Breakdown of Tropical Hardwood Species2015Conference paper (Other academic)
    Abstract [en]

    The sawing of tropical hardwood species is a big challenge for sawmills in developing countries. In order to investigate sawing strategies and volume recovery of tropical hardwood species, a log shape database was created using a portable 3D laser scanner. The data were collected in Mozambique, where twelve Jambirre (Millettia stuhlmannii Taub.) and five Umbila (Pterocarpus angolensis DC) logs were scanned. The logs were selected among the most commercialized species and the crook was the main selection parameter. In addition, straight logs were incorporated as reference. A saw simulation Matlab algorithm that combines skew and rotation was developed. The results show that point cloud data from the 3D scanner provide detailed models of the external log geometry and accurately describe the log shapes and volumes. Preliminary results from breakdown simulation revealed that the through-and-through sawing pattern yields more than the cant saw pattern and that the increase in yield was almost the same for both species.

  • 2.
    Ah Shenga, Pedro António
    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.
    Simulated Breakdown of Two Tropical Hardwood Species2015In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, no 4, p. 450-456Article in journal (Refereed)
    Abstract [en]

    A simulation study has been performed on a small log database of tropical hardwoods consisting of 10 Jambirre (Millettia stuhlmannii Taub.) and 5 Umbila (Pterocarpus angolensis D.C.) logs. The outer log shape was acquired by a 3D laser scanner before sawing and the heartwood content was estimated by measurement on images of the centre slabs after through-and-through sawing. Yield and value recovery using different sawing techniques and different sawing patterns, together with rotational and skew positioning errors, are presented. The results show that through-and-through sawing in the best rotation and skew positions tested improves the yield of Umbila logs by an average of 4.5 percentage points and Jambirre logs by 3.6 percentage points compared to cant sawing. It can be concluded that positioning and sawing patterns have a great influence on the yield and value recovery of these species and that log grade and species have an impact on the sawing pattern that should be used.

  • 3.
    Ah Shenga, Pedro António
    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.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Simulation of Tropical Hardwood Processing: Sawing Methods, Log Positioning, and Outer Shape2015In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, no 4, p. 7640-7652Article in journal (Refereed)
    Abstract [en]

    To increase understanding of breakdown strategies for Mozambican timber, simulations were carried out using different sawing patterns that can be alternatives to the low degree of refinement performed for export today. For the simulations, 3D models of 10 Jambirre and 5 Umbila logs were used. The log shape was described as a point cloud and was acquired by 3D-laser scanning of real logs. Three sawing patterns (cant-sawing, through-and-through sawing, and square-sawing) were studied in combination with the log positioning variables skew and rotation. The results showed that both positioning and choice of sawing pattern had a great influence on the volume yield. The results also showed that the log grade had an impact on the sawing pattern that should be used for a high volume yield. The volume yield could be increased by 3 percentage points by choosing alternative sawing patterns for fairly straight logs and by 6 percentage points for crooked logs, compared to the worst choice of sawing pattern.

  • 4.
    Ah Shenga, Pedro
    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.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    3D Phase-shift Laser Scanning of Log Shape2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 4, p. 7593-7605Article in journal (Refereed)
    Abstract [en]

    In this paper, a portable scanner to determine the 3D shape of logs was evaluated and compared with the measurement result of a computer tomography scanner. Focus was on the accuracy of the shape geometry representation. The objective is to find a feasible method to use for future data collection in Mozambique in order to build up a database of logs of tropical species for sawing simulations. The method chosen here was a 3D phase-shift laser scanner. Two logs, a birch log with bark and a Scots pine log without bark, were scanned, resulting in 450 cross sectional “images” of the pine log and 300 of the birch log. The areas of each point cloud cross section were calculated and compared to that of the corresponding computer tomography cross section. The average area difference between the two methods was 2.23% and 3.73%, with standard deviations of 1.54 and 0.91, for the Scots pine and birch logs, respectively. The differences in results between the two logs are discussed and had mainly to do with presence of bark and mantle surface evenness. Results show that the shape measurements derived from these methods were well correlated, which indicates the applicability of a 3D phase-shift laser scanning technology for gathering log data.

  • 5.
    Ah Shenga, Pedro
    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.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Log sawing positioning optimization and log bucking of tropical hardwood species to increase the volume yield2017In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, no 4, p. 257-262Article in journal (Refereed)
    Abstract [en]

    The sawmill industry is a very important link in the Mozambique forest products value chain, but the industry is characterized by undeveloped processing technology and high-volume export of almost unrefined logs. The low volume yield of sawn timber has been identified as a critical gap in the technological development of the industry. To improve the profitability of the industry, there is thus a need to develop methods and techniques that improve the yield. In this paper, different positioning of logs prior to sawing and the possibility of increasing the volume yield of crooked logs by bucking the logs before sawing have been studied. A computer simulation was used to study the cant-sawing and through-and-through sawing of the logs to determine the volume yield of sawn timber from the jambirre (Millettia stuhlmannii Taub.) and umbila (Pterocarpus angolensis DC.) species. The optimal position, i.e. the position of the log before sawing that gives the highest volume yield of sawn timber for a given sawing pattern when the positioning parameters, offset, skew and rotation, are considered gave a considerable higher volume yield than the horns-down position. By bucking very crooked logs and using the horns-down positioning before sawing, the volume yield can be of the same magnitude as that obtained by optimal positioning on full-length (un-bucked) logs. The bucking reduces the crook of the logs and hence increases the volume yield of sawn timber.

  • 6.
    Ah Shenga, Pedro
    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.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    The Effect of Log Position Accuracy on the Volume Yield in Sawmilling of Tropical Hardwood2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 4, p. 9560-9571Article in journal (Refereed)
    Abstract [en]

    This study investigated the effect of the positioning of the log before sawing on the volume yield of sawn timber from tropical hardwood species. Three positioning parameters were studied, the offset, skew, and rotation, combined with two sawing patterns of cant-sawing and through-and-through sawing. A database consisting of two tropical hardwood species with very different outer shapes, jambirre (Millettia stuhllmannii Taub.) and umbila (Pterocarpus angolensis DC.), was used to simulate the sawing process. The result of the simulation revealed that, according to the combined effect of offset, skew, and rotation positioning, the positioning of the log before sawing is extremely important to achieve a high volume yield of sawn timber. The positioning parameter that has the highest effect on the volume yield is the rotation, and the variation in the volume yield associated with a deviation in the positioning can reduce the volume yield of sawn timber by between 7.7% and 12.5%.

  • 7.
    Björngrim, Niclas
    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.
    Forsman, Samuel
    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.
    Model-based production for engineered-to-order joinery products2012In: World Conference on Timber Engineering, WCTE: Final Papers / [ed] Pierre Quenneville, New Zealand Timber Design Society , 2012, p. 697-701Conference paper (Refereed)
    Abstract [sv]

    När det levereras snickeri-produkter till byggindustrin som utvecklas mot kundorder, tar tillverkaren tar ofta ansvar för hela värdeflödet från offertförfrågan till slutmontering på byggarbetsplatsen. Det finns dock luckor i informationsflödet mellan varje aktör i den interna leveranskedjan, vilket leder till osäkerheter i kvalitet och påverkar processeffektiviteten. En del av problemen kommer från avsaknaden av rutiner för dokumentation av både ändringar och tillägg till den ursprungliga planen. För att kompensera för bristen på dokumentation, hantverkare förlita sig på sina färdigheter och erfarenhet, vilket ofta leder till onödiga och tidskrävande ad hoc-lösningar. Varje aktör i kedjan tillbringar tidåterupptäcka tidigare känd information istället för att hänvisa till dokumentationen. I denna artikel föreslås ett modell-baserad angreppsätt, som utnyttjar informations-och kommunikationsteknik (IKT) för att förbättra information- och kunskapsutbytet genom värdekedjan för bättre spridningav relevant information till berörda aktörer.

  • 8.
    Bomark, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Towards better understanding of forestry-wood chain simulation through visualization and interactivity2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Simulation studies performed on the forestry-wood chain trend towards either complicated calculations on large data-sets, statistical exercises on endless production data, optimisations on specific sub domains, or a combination of the above. The studies are often presented through graphs showing how scalars such as value, profit, or yield fluctuate when parameters of the simulation model are tweaked.The simulation models are usually stringed together from a series of operations performed in various software packages, scripts, macros and purpose written code. Reusing code from past studies is common practise, either as part of the new program, or by simply running the data through an executable and parsing the results in the next operation. Since there is no framework built around the operations, changing the input data will often mean that you have to start again from the top, guiding the data through all the different steps manually. To make things worse; the simulation model, the experiment code, and the analysis code tend to be mixed together making validation and verification difficult.Keeping track of how each operation impacts the result is difficult, and understanding how different parameters interact with each other on a system-wide basis is hopeless.Despite already being complex, most studies omit important aspects of the system they are modelling. Processing time, stochastic behaviour, separation of experimental data from model data, and so on. At the same time, if the fidelity of the simulation models continue to increase, they will eventually become too unwieldy to comprehend.Despite this, simulation is one of the most important tools available when trying to improve the forestry-wood chain, and the results that have been produced through the use of simulation are awe-inspiring. With proper tools and methodology, the integrated simulation model of the forestry-wood chain is not far away.This document is an attempt at finding tools that help design understandable simulation models of the complex systems in the forestry-wood chain. The hypothesis is that visualisation and interactivity can give alternative feedback on simulation models, providing better foundations for decisions than scalar measures like profit or yield.

  • 9.
    Bomark, Peter
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Evertsen, Gunn
    Northern Research Institute.
    Brox, Ellen
    Northern Research Institute.
    Hirche, Johannes
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yliräisänen-Seppänen, Pia
    Rovaniemi University of Applied Sciences.
    A prototype social learning platform for children with diabetes type 12012In: Proceeding of the 16th International Academic MindTrek Conference 2012: Envision Future Media Environments, New York: Association for Computing Machinery, Inc. , 2012, p. 211-213Conference paper (Refereed)
    Abstract [en]

    Children diagnosed with diabetes type 1 are bombarded with information and have a hard time understanding it all. Existing information material consists mostly ofbrochures and textbooks, giving little opportunity for testing and trial-and-error without consequences. A social platform with learning games gives the children an opportunity to experiment and find peer support, which is important for coping with a life long disease.

  • 10.
    Bomark, Peter
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hirche, Johannes
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Colour visualisation of real virtual timber using image quilting2015In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 73, no 6, p. 837-839Article in journal (Refereed)
    Abstract [en]

    When presenting images of wood obtained through x-ray computed tomography to an audience inexperienced in interpreting radiological images, explaining the correspondence between mass attenuation and features of wood could be time consuming and confusing. Realistically colourised attenuation images might be a suitable option in order to facilitate understanding of the images. Mass attenuation and colour of wood does not have a simple correlation, so naive grey-scale to colour conversion does not work. This paper describes how image quilting can be used to transfer colour information from a image pair where both mass attenuation and colour is known to a target mass attenuation image. An example of this method applied on scots pine shows that it is capable of retaining the major structures of wood, such as year rings and knots. The method could allow for easier understanding of simulation studies where logs scanned using x-ray computed tomography are virtually sawn.

  • 11.
    Brox, Ellen
    et al.
    Northern Research Institute.
    Evertsen, Gunn
    Northern Research Institute.
    Bomark, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hirche, Johannes
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yliräisänen-Seppänen, Pia
    Rovaniemi University of Applied Sciences.
    User centric social diabetes game design for children2012In: Proceeding of the 16th International Academic MindTrek Conference 2012: Envision Future Media Environments, New York: Association for Computing Machinery, Inc. , 2012, p. 291-293Conference paper (Refereed)
    Abstract [en]

    Children recently diagnosed with diabetes type 1 require lots ofinformation and feel scared, alone and different. Most of theexisting educational material is on paper. Games with relevantlearning content are mainly small minigames in English. There isa need for more material with a focus on user needs, particularlylearning–by-doing material. Peer support is known to beimportant for this user group. We present a concept for a sociallearning game that is engaging and fun for diabetic children.

  • 12.
    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.

  • 13.
    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)
  • 14.
    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

  • 15. Rebstock, Florian
    et al.
    Bomark, Peter
    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.
    Makerjoint, a new concept for joining members in timber engineering: Strength test and failure analyses2015In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, no 4, p. 397-404Article in journal (Refereed)
    Abstract [en]

    The wood construction industries are becoming more focused on climate change and resourcedepletion, and individual and industrial consumption must reflect a greater degree of concern for theclimate and environmental wellbeing. This paper presents a new concept for timber engineering, thepurpose being to acquire information about the failure modes and the tensile and compressivestrengths of two types of joint, the Simple Gooseneck and Thick Gooseneck, that can be used in anew concept for joining members in timber structures. This Makerjoint concept uses laminated veneerlumber (LVL) as nodes in regions with a pronounced non-uniform stress distribution and sawn timberin regions with a more uniform stress distribution. No metal fasteners or adhesives are used in thejoint between timber and LVL. The concept is intended for joints using 3-axis CNC machinery and tobe a system for on-site- and pre-fabrication of e.g. small houses, emergency shelters and exhibitionstands. The joints have a higher compressive than tensile strength. The joints exhibited brittle failure intension (beam and/or node failure) and buckling occurred in compression around the thinnest crosssection of the beams. Suggestions are made for how the mechanical properties of the joints can beimproved.

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