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  • 1.
    Ah Shenga, Pedro
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Bomark, Peter
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Broman, Olof
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    3D Phase-shift Laser Scanning of Log Shape2014Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, nr 4, s. 7593-7605Artikel i tidskrift (Refereegranskat)
    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.

  • 2.
    Ahmed, Sheikh Ali
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Cloutier, Alain
    Wood Research Center (CRB), Department of Wood and Forest Sciences, Faculty of Forestry, Geography and Geomatics, Laval University, Quebec.
    Fang, Chang-Hua
    Wood Research Center (CRB), Department of Wood and Forest Sciences, Faculty of Forestry, Geography and Geomatics, Laval University, Quebec.
    Elustondo, Diego
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Anatomical properties and process parameters affecting blister/blow formation in densified European aspen and downy birch sapwood boards by thermo-hygro-mechanical compression2013Ingår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 48, nr 24, s. 8571-8579Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Approximately, 13.5 % of the standing volume of productive forest land in Sweden is covered by birch and aspen, which provides the vast potential to produce value-added products such as densified wood. This study shows whether it is possible to densify those species with a thermo-hygro-mechanical (THM) process using heat, steam, and pressure. In this process, transverse compression on thin European aspen (Populus tremula) and downy birch (Betula pubescens) boards was performed at 200 ºC with a maximum steam pressure of 550 kPa. To obtain a theoretical 50 % compression set, the press’s maximum hydraulic pressure ranged from 1.5 to 7.3 MPa. Preliminary tests showed that ~75 % of the birch boards produced defects (blisters/blows) while only 25 % of the aspen boards did. Mainly, radial delamination associated with internal checks in intrawall and transwall fractures caused small cracks (termed blisters) while blows are characterized by relatively larger areas of delamination visible as a bumpy surface on the panel. Anatomical investigations revealed that birch was more prone to those defects than aspen. However, those defects could be minimized by increasing the pre-treatment time during the THM processing.

  • 3.
    Björngrim, Niclas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Fjellström, Per-Anders
    Science Partner.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Factory Mounted and Retrofit Passive Resistance Sensors Adapted to Monitor Moisture Content in Timber Bridges2017Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, nr 4, s. 7218-7227Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The biggest threats to the longevity of a timber bridge are rot and decay. Wood protection by design, inspections, and monitoring of the bridge for elevated moisture content will ensure that the full service life of the structure can be achieved. Today's sensors for moisture content measurements are limited in their functionality and range. This paper presents a sensor that can be both factory installed and retrofitted, which can measure the moisture content through the cross-section of the member in a timber bridge. The sensor has been mounted on Sundbron bridge during manufacturing and retrofitted on Gislaved bridge. The ensuing measurements helped to adjust a design flaw on Gislaved bridge. Monitoring of Sundbron showed that the bridge deck dried up after the bridge had been exposed to sleet and snow during the on-site assembly of the stress laminated bridge deck

  • 4.
    Björngrim, Niclas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Fjellström, Per-Anders
    SP - Science Partner.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Long Term Evaluation of Factory Installed And Retro Fitted Moisture Content Sensor adapted for Timber Bridges2017Ingår i: Artikel i tidskrift (Refereegranskat)
  • 5.
    Björngrim, Niclas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Fjellström, Per-Anders
    SP - Science Partner.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Resistance measurements to find high moisture content inclusions adapted for large timber bridge cross-sections2017Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, nr 2, s. 3570-3582Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One challenge of monitoring and inspecting timber bridges is the difficulty of measuring the moisture content anywhere other than close to the surface. Damage or design mistakes leading to water penetration might not be detected in time, leading to costly repairs. By placing electrodes between the glulam beams, the moisture content through the bridge deck can be measured. Due to the logarithmic decrease of the resistance in wood as a function of electrode length, the model must be calibrated for measurement depth. Two models were created: one for electrode lengths of 50 mm and one for electrode lengths up to 1355 mm. The model for short electrodes differed by no more than 1 percentage points compared with the oven dry specimens. The model for long electrodes differed up to 2 percentage points for lengths up to 905 mm, and over that it could differ up to 4 percentage points.

  • 6.
    Björngrim, Niclas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Gustafsson, Anders
    SP Trätek, SP Technical Research Institute of Sweden, Skellefteå.
    Pousette, Anna
    Luleå tekniska universitet, SP Trätek.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Health monitoring of a cable-stayed timber footbridge2011Konferensbidrag (Refereegranskat)
  • 7.
    Björngrim, Niclas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Wang, Alice
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Multivariate Screening of the Weather Effect on Timber Bridge Movements2016Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 4, s. 8890-8899Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monitoring displacements and weather impact of complex structures such as a large cable stayed footbridge generates large amount of data. In order to extract, visualize and classify health-monitoring data to get a better comprehension multivariate statistical analysis is a powerful tool. This paper is a screening to evaluate if principal component analysis is useful on health monitoring data. Principal component analysis (PCA) and projections to latent structures by means of partial least squares (PLS) modeling were used to achieve a better understanding of the complex interaction between bridge dynamics and weather effects. The results show that principal component analysis (PCA) give good overview of the collected data, and PLS modeling show that winds from east and west best explain bridge movements.

  • 8.
    Björngrim, Niclas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Wang, Xiaodong (Alice)
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Moisture Content Monitoring of a Timber footbridge2016Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 2, s. 3904-3913Artikel i tidskrift (Refereegranskat)
  • 9.
    Bomark, Peter
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hirche, Johannes
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Colour visualisation of real virtual timber using image quilting2015Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 73, nr 6, s. 837-839Artikel i tidskrift (Refereegranskat)
    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.

  • 10.
    Buck, Dietrich
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Mechanics of diagonally layered cross-laminated timber2018Konferensbidrag (Refereegranskat)
  • 11.
    Buck, Dietrich
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Production and In-Plane Compression Mechanics of Alternatively Angled Layered Cross-Laminated Timber2018Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, nr 2, s. 4029-4045Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increasing awareness of sustainable building materials has led to interest in enhancing the structural performance of engineered wood products. This paper reports mechanical properties of cross-laminated timber (CLT) panels constructed with layers angled in an alternative configuration on a modified industrial CLT production line. Timber lamellae were adhesively bonded together in a single-step press procedure to form CLT panels. Transverse layers were laid at an angle of 45°, instead of the conventional 90° angle with respect to the longitudinal layers’ 0° angle. Tests were carried out on 20 five-layered CLT panels divided into two matched groups with either a 45° or a 90° configuration; an in-plane uniaxial compressive loading was applied in the principal orientation of the panels. These tests showed that the 45°-configured panels had a 30% higher compression stiffness and a 15% higher compression strength than the 90° configuration. The results also revealed that the 45°-configured CLT can be industrially produced without using more material than is required for conventional CLT 90° panels. In addition, the design possibility that the 45°-configured CLT can carry a given load while using less material also suggests that it is possible to use CLT in a wider range of structural applications.

  • 12.
    Buck, Dietrich
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Wang, Alice
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Gustafsson, Anders
    SP Technical Research Institute of Sweden, SP Sustainable Built Environment, Skellefteå.
    Further Development of Cross-Laminated Timber (CLT): Mechanical Tests on 45° Alternating Layers2016Ingår i: WCTE 2016 : Proceedings, Vienna: Vienna University of Technology, Austria , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

     

    In this paper, a series of experimental bending and compression tests were performed on cross-laminated timber (CLT) products with ±45° alternating layers, to evaluate their performance against conventional panels of 90° orientation. Engineered wood products, such as CLT with ±45° alternating layers can provide opportunities for greater use in larger and more sustainable timber constructions. A total of 40 panels, manufactured in an industrial CLT production line with either of these two configurations, were tested and compared. Panels were evaluated in bending tests n=20 and the remaining ones in compression tests. Results showed that 35% increased the strength in the four-point bending tests for panels containing ±45° alternating layers compared with the 90° alternating layers. Compression strength was increased by 15%. Stiffness increased by 15% in the four-point bending and 30% in the compression. The results indicate that CLT containing ±45° alternating layers has increased strength and stiffness compared to 90° alternating layers. These findings suggest that further developments in CLT are feasible in advanced building applications.

  • 13.
    Buck, Dietrich
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Wang, Alice
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Gustafsson, Anders
    SP Technical Research Institute of Sweden, SP Sustainable Built Environment, Skellefteå, Sweden, SP Trätek, SP Technical Research Institute of Sweden, Skellefteå.
    Bending Properties of Cross Laminated Timber (CLT) with a 45° Alternating Layer Configuration2016Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 2, s. 4633-4644Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bending tests were conducted with cross laminated timber (CLT) panels made using an alternating layer arrangement. Boards of Norway spruce were used to manufacture five-layer panels on an industrial CLT production line. In total, 20 samples were tested, consisting of two CLT configurations with 10 samples of each type: transverse layers at 45° and the conventional 90° arrangement. Sample dimensions were 95 mm × 590 mm × 2000 mm. The CLT panels were tested by four point bending in the main load-carrying direction in a flatwise panel layup. The results indicated that bending strength increased by 35% for elements assembled with 45° layers in comparison with 90° layers. Improved mechanical load bearing panel properties could lead to a larger span length with less material.

  • 14.
    Buck, Dietrich
    et al.
    Department of Engineering Sciences and Mathematics, Luleå University of Technology.
    Wang, Xiaodong (Alice)
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Gustafsson, Anders
    SP Technical Research Institute of Sweden, SP Sustainable Built Environment, Skellefteå, Sweden.
    Comparison of Different Assembling Techniques Regarding Cost, Durability, and Ecology: A Survey of Multi-layer Wooden Panel Assembly Load-Bearing Construction Elements2015Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, nr 4, s. 8378-8396Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wood is a pure, sustainable, renewable material. The increasing use of wood for construction can improve its sustainability. There are various techniques to assemble multi-layer wooden panels into prefabricated, load-bearing construction elements. However, comparative market and economy studies are still scarce. In this study, the following assembling techniques were compared: laminating, nailing, stapling, screwing, stress laminating, doweling, dovetailing, and wood welding. The production costs, durability, and ecological considerations were presented. This study was based on reviews of published works and information gathered from 27 leading wood product manufacturing companies in six European countries. The study shows that the various techniques of assembling multi-layer wooden construction panel elements are very different. Cross laminated timber (CLT) exhibited the best results in terms of cost and durability. With regard to ecological concerns, dovetailing is the best. Taking into account both durability and ecological considerations, wooden screw-doweling is the best. These alternatives give manufacturers some freedom of choice regarding the visibility of surfaces and the efficient use of lower-quality timber. CLT is the most cost-effective, is not patented, and is a well-established option on the market today.

  • 15.
    Chen, Tingjie
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Wu, Zhenzeng
    College of Material Engineering, Fujian Agricultural and Forestry University.
    Wei, Wei
    College of Material Engineering, Fujian Agricultural and Forestry Universit.
    Xie, Yongqun
    College of Material Engineering, Fujian Agricultural and Forestry Universit.
    Wei, Qihua
    College of Material Engineering, Fujian Agricultural and Forestry Universit.
    Wang, Alice
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Optimizing Refining Conditions of Pinus massoniana Cellulose Fibers for Improving the Mechanical Properties of Ultra-Low Density Plant Fiber  Composite (ULD_UFC)2017Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, nr 1, s. 8-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Response surface methodology was used to optimize the refining conditions of Pinus massoniana cellulose fiber and to improve the mechanical properties of ultra-low density plant fiber composite (ULD_PFC). The effects and interactions of the pulp consistency (X1), the number of passes (X2), and the beating gap (X3) on the internal bond strength of ULD_PFC were investigated. The results showed that the optimum internal bond strength (91.72 ± 2.28 kPa) was obtained under the conditions of 8.0% pulp consistency, two passes through the refiner, and a 30.0 μm beating gap. Analysis of the physical properties of the fibers and handsheets showed that the fibrillation of fibers with optimum refining conditions was improved. Also, the tear index of the optimal specimen was 13.9% and 24.5% higher than specimen-1 with a lowest beating degree of 24 oSR and specimen-6 with a highest beating degree of 73 oSR, respectively. Consequently, the optimal refining conditions of the fibers are valid for preparing ULD_PFCs.

  • 16.
    Chen, Tingjie
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi. tingjie.chen@ltu.se .
    Xie, Yongqun
    Department of Material Science and Engineering, Fujian Agriculture and Forestry University, Fuzhou.
    Wei, Qihua
    Department of Material Science and Engineering, Fujian Agriculture and Forestry University, Fuzhou.
    Wang, Alice
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Liu, Jinghong
    Department of Material Science and Engineering, Fujian Agriculture and Forestry University, Fuzhou.
    Effect of Refining on Physical Properties and Paper Strength of Pinus massoniana and China Fir Cellulose Fibers2016Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 3, s. 7839-7848Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To obtain a suitable refining process for Pinus massoniana cellulose fibers (PMCF) and China fir cellulose fibers (CFCF), the effects of the beating gap and the pulp consistency on the physical properties and the morphology of the two cellulose fibers were investigated. The results showed that the physical properties of the PMCF and the CFCF were well affected by the beating gap and the pulp consistency. The CFCF showed a smaller weight-average length and width than that of the PMCF. The CFCF exhibited smaller weight-average length, width, and kink index than the PMCF. It is easy to get the high beating degree, indicating it is more easily to be refined. Additionally, the tensile index and burst index of PMCFP and CFCFP increased with increasing beating degree, while the tear index decreased. Compared to the CFCF, the paper made from PMCF had superior strength properties. Consequently, the PMCF was suitable for refining with a high pulp consistency and a medium beating gap, whereas the CFCF had a medium pulp consistency and a big beating gap.

  • 17.
    Chen, Tingjie
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Xie, Yongqun
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Wei, Qihua
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Wang, Xiaodong (Alice)
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Liu, Jinghong
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Lin, Ming
    College of Material Engineering, Fujian Agriculture and Forestry University.
    Improving the Mechanical Properties of Ultra-Low Density Plant Fiber Composite (ULD_PFC) by Refining Treatment2016Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 4, s. 8558-8569Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To improve the mechanical properties of ultra-low density plant fiber composite (ULD_PFC), a suitable beating process to improve the fibrillation of cellulose fibers and maintain their length was investigated. The physical properties of cellulose fibers and papers, surface chemical bonds, and internal bond strength (IB) of ULD_PFCs were analyzed. The results showed that the beating degrees, degree of fibrillation, and fiber fines increased with the decreasing of beating gap, except for the fiber weight-average length, width, kink index, and curl index. The tensile index and burst index of paper showed an increasing trend with an increase in beating degree, while the tear index showed a decreasing trend. FTIR results showed that intermolecular and intramolecular hydrogen bonds in ULDF were broken. A suitable beating gap of 30 μm with a beating degree of 35 °SR was obtained. The corresponding IB was 50.9 kPa, which represented an increase of 73.1% over fibers with a beating degree of 13 °SR.

  • 18.
    Couceiro, José
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sehlstedt-Persson, Margot
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hansson, Lars
    Norwegian University of Science and Technology (NTNU), Department of ICT and Natural Sciences, Norway.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    CT scanning of capillary phenomena in bio-based materials2017Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, nr 4, s. 181-187Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    X-ray computed tomography (CT) is a powerful tool for the non-destructive study of dynamic moisture processes in wood and other bio-based materials. In the CT facilities at Luleå University of Technology, it is possible to study wood-moisture relations such as water absorption, drying and related material deformation under a temperature- and humidity-controlled environment.An increase in the use of bio-based materials in building construction has led to an increased interest in capillary phenomena in these materials, because of an increasing number of moisture-related damage in timber and hybrid-timber buildings. This article shows some examples of how different bio-materials used in construction interact with liquid water over time. The overall purpose has been to develop the CT technique as a powerful tool for the determination and visualization of capillary flow that can be a base for modelling and an increased understanding of moisture flow in new bio-based building materials.Early-stage observation of the behaviour of different traditional and new bio-based building materials shows that CT scanning, combined with image processing, has a high potential to be used in performing non-destructive and non-contact tests that can help to increase the knowledge of water-material interactions and develop building materials with an optimized performance.

  • 19.
    Cristescu, Carmen
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Could colour predict hardness of hot-ptressed self-laminated beech boards2015Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, nr 4, s. 150-156Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laminated self-bonded densified boards were obtained by pressing five veneers of beech(Fagus sylvatica L.) parallel-grain-oriented, without adhesive and without surface activation. Theboards were pressed according to an experimental design based on fifteen different combinations ofpressing parameters: temperature (200, 225, and 250°C), pressure (4, 5, and 6MPa), and time (240,300, and 360s). The image of the 40 board edges (radial sections) was analysed with ImageJ softwarein the red-green-blue (RGB) colour space. Brinell hardness tests were also performed. The resultsshow an almost linear relation between the brightness values (defined as the arithmetic mean of theRGB channels) and the Brinell hardness. It is suggested that brightness is a predictor of strength forself-bonded laminated boards.

  • 20. Eklund, Urban
    et al.
    Grönlund, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Hagman, Olle
    Mesurement of cant feeding disturbances during sawing1999Ingår i: IWMS 14: 14e Séminaire international sur l'usinage du bois, 12-19 septembre 1999, Paris, Épinal, Cluny, France : actes du séminaire, Montpellier: CIRAD , 1999, s. 193-202Konferensbidrag (Refereegranskat)
  • 21. Garzon, Alirio
    et al.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Future requirement for sustainable building envelope2018Konferensbidrag (Refereegranskat)
  • 22. Grundberg, Stig
    et al.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Measuring active wood fracture surfaces1993Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 51, nr 1, s. 49-54Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This report describes a measurement method, based on image processing, for calculating the proportion of active wood fractures in a sheet of particle board that has been pulled apart. This method gives an indirect measurement of the effectiveness of the glue in a particle board. The basic procedure is to separate different surfaces on both sides of the tensile fracture. The separation of the glue covered surfaces from wood surfaces has been enhanced by a development process. The separated surfaces for each side, represented in the form of a binary image, are added, and a proportion of the surface with coinciding wood surfaces represents the proportion of wood fractures. The error analysis covers the randomly obtained coinciding surfaces.

  • 23. Grundberg, Stig
    et al.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Multivariate image analysis methods to classify features on scots pine: evaluation of a multisensor approach1993Ingår i: Scan Pro: 5th International Conference on Scanning Technology & Process Control for the Wood Products Industry : Atlanta GA USA Renaissance Hotel, October 25-27, 1993 : conference proceedings / [ed] Ryszard Szymani, San Francisco: Miller Freeman , 1993Konferensbidrag (Refereegranskat)
  • 24. Grundberg, Stig
    et al.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Rese- och konferensrapport: USA 19891990Rapport (Övrigt vetenskapligt)
  • 25. Grundberg, Stig
    et al.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Utveckling av mätmetod för beräkning av andel träbrott i spånskiva1991Rapport (Övrigt vetenskapligt)
  • 26.
    Grönlund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Hagman, Olle
    Grönlund, Ulla
    Nordkalottfura1992Rapport (Övrigt vetenskapligt)
  • 27.
    Gustafsson, Anders
    et al.
    SP Technical Research Institute of Sweden, Skellefteå.
    Nasu, Hideyuki
    Nippon Institute of Technology, Department of Architecture, 4-1 Gakuendai, Miyashiro-machi, Minamisaitama-gun, Saitama Pref., 345-8501, Japan.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Introduction of a new building system in Europe: big fram, results and conclusions2012Ingår i: World Conference on Timber Engineering: Final Papers - Architecture and Engineering Case Studies / [ed] Pierre Quenneville, Auckland: New Zealand Timber Design Society , 2012, s. 140-147Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents and discusses the results and work carried out in a feasibility study, in cooperation with Swedish companies and a Japanese company to evaluate the possibility to introduce and adapt a new building system in Europe. The system is a column-beam systems developed in Japan and have been analyzed and evaluated in this project regarding to European conditions. The work carried out for about 18 months starting in June 2008 and finishing in 2010. The choice of the building system is determined by both performance and economy. The build system has a potential for various construction projects and has numerous advantages. The system flexibility should be increased to meet other types of construction and thereby increase its market potential. Each building is a unique object, so there is no pre-given solution what system is the best in each case.

  • 28.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Analys av träytors färg: sammanställning av en doktorandkurs1996Rapport (Övrigt vetenskapligt)
  • 29.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Analysis and calibration of time dependent colour changes on wood surfaces with PLS and multiplicative signal correction2005Ingår i: Proceedings: 9th International IUFRO Wood Drying Conference, Nanjing Forestry University , 2005Konferensbidrag (Refereegranskat)
  • 30.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Automatic quality grading of logs with TINA a gamma ray log scanner1993Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 8, s. 583-590Artikel i tidskrift (Refereegranskat)
  • 31.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Datoranvändning inom trämanufakturindustrin: en översikt över möjligheter att använda datorer i tekniska sammanhang1987Rapport (Övrigt vetenskapligt)
  • 32.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Detektering av kådlåpor i gran: sammanfattning av förstudie2004Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Gran har idag begränsade möjligheter att förädlas till produkter för inomhusbruk på grund av förekomsten av kådlåpor. För att kunna vidareförädla gran i moderna processer krävs automatiska eller manuella metoder att ta reda på eventuell förekomst av defekter inne i materialet som helt kan nedklassa en slutprodukt. Kådlåpor har en form som följer en årsring och har därmed en i huvudsak 2-dimesionell form som följer tangentialytan i trädet. Detta medför att kådlåpan ofta ger upphov till tillfredsställande kontrast i två riktningar men inte vid genomlysning i den tredje i riktningen mot tangentialplanet. Förhållandet mellan kådlåpans tjocklek och övrigt trämaterial blir för litet och kådan/luftfickans annorlunda egenskaper som densitet, elektriska egenskaper eller fasskillnader ger inte urskiljbar kontrast. Kådlåpans varierande innehåll av luft och/eller kåda medför att detekteringssituationen blir mer komplex än om man hade ett homogent material i defekten. Projektet avser att i en förstudie nyttja och utvärdera känd teknik för att välja den sensor eller de kombinerade sensorsystem som kan hitta ej synliga kådlåpor i sågad gran. Slutmålet är detektering i en online lösning. Följande sensorer har testats: * för skanning av ytor: RGB, RGB + Uv belysning, Trakeideffekt, IR * för skanning av medelvärde av absorption i en riktning: Planröntgen * för tredimensionell representation av provkropp: CT-skanning och simulerad Cone-beam ScanningResultaten från ytskanningsförsöken visar att en industriell applikation är möjlig Resultaten från detektion av inre egenskaper är: * att CT -skanning fungerar för automatisk detektering men är ej möjligt att genomföra i realtidsapplikation med tillgänglig teknik* Planröntgen fungerar med kådlåpor parallella med djupdimensionen men inte för kådlåpor parallella med ytan * Cone-beam ger något bättre upplösning än i planröntgenfallet men sämre än CT rekonstruktion i det simulerade fallet. Idag finns inte de 2-D röntgensensorer som krävs för att omsätta detta i en industriell applikation.

  • 33.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Kådlåpor: en förstudie för att finna metoder för detektering av kådlåpor i gran2003Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Har funnit några lösningar? Ja, men inte inom prioriterade områden.RESULTAT: * Ny metod för förbättrad klassificering av kådlåpor på ytan identifierad och överlämnad till två leverantörer av avsyningssystem för träprodukter. Metoden som går att implementera i realtidssystem nyttjar den fluorescens som uppkommer vid UV belysning av kådlåpor. Kommersiellt intressant. * Möjlig metod att hitta kådlåpor i 3-dimensionella strukturer identifierad genom simulering. Fortfarande saknas kommersiella system och sensorer som kan nyttjas för en realtidslösning. Metoden klarar inte att upplösa kådlåpor i vissa riktningar i den simulerade provbiten och i ännu mindre utsträckning i en stock. * De försök som genomförts för att identifiera kådlåpor i en industriell tomograf visar på en möjlighet att detektera dem med normala bildbehandlings-algoritmer, problemen är för låg upplösningen för mindre kådlåpor samt att den tomograf som testats inte klarar av den miljö som finns i sågverk. * Vi har inte hittat några tecken på att logskannerdata eller andra stockbaserade yttreform- eller densitetsvariationsparametrar kan användas för att prediktera förekomst av kådlåpor i gran. FÖLJANDE KOMPLETTERANDE FÖRSÖK AV ANSATSER FÖR ATT LÖSA PROBLEMET HAR INTE GENOMFÖRTS DÅ LEDNINGSGRUPPEN BESLUTADE AVSLUTA PROJEKTET MED LÄGRE BUDGET ÄN PLANERAT: Beräkning av sannolikhet för förekomst av kådlåpor baserad på frekvensen på synliga ytor i sönderdelad stock. DVS om man hittar en eller flera kådlåpor på en planka skall man då sortera ut den? Sensortest med IR laser för att utreda maxdjup där icke synlig kådlåpa kan detekteras Test av mikrovågssensor

  • 34.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Multivariate prediction of wood surface features using an imaging spectrograph1997Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 55, nr 6, s. 377-382Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Picea abies , Pinus sylvestris), is reported, showing verified 92-94% correct classification. It is shown that compression wood classification could be reduced to an uncomplicated linear model using just a few spectral components where the most important one is around the limit for visible light going to the Ultraviolet spectra. This almost univariate behaviour for the model is not the common behaviour for other wood surface features

  • 35.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    On reflections of wood: wood quality features modelled by means of multivariate image projections to latent structures in multispectral images1996Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Classifying logs and boards has an essential economic impact on the forest products industry. In a modern production chain, quality control and raw material specifications are essential to fulfill production system demands as well as end user demands. The subject of the thesis is automatic grading of wood represented by its appearance in various stages of decomposition of a tree, i.e. as logs, boards, components or individual surface objects often labelled as defects. The main method used is based on multivariate measurements and data compression by means of principal component analysis (PCA) and prediction modelling with projections to latent structures (PLS). The thesis adresses mainly feature identification and feature extraction of properties that have an impact on automatic grading of sawn softwood boards. The features are modelled by means of their appearance in the multivariate image space obtained by scanning and integrating images utilizing different imaging sensors. The main goals of this thesis are: to introduce multivariate image analysis (MIA) and multivariate image projections to latent structures (MIPLS) combined with experimental design as a research tool for wood feature description and to give a survey of its applications to identify and extract features feasible for classification of softwood surfaces to investigate the use of an imaging spectrograph combined with a smart sensor for real time grading of sawn products to present the necessity of installing human evaluation and system interaction possibilities into automatic wood inspection systems to obtain good performance This thesis contributes to the wood research field by the multivariate approach so far with a limited use in wood technology research with a few outlayers. The main contributions are: the introduction of PLS and MIPLS as soft modelling tools for calibration and prediction modelling of wood features the evaluation of the imaging spectrograph/MIPLS concept to model the spectral behaviour of the interaction between visible light, the wood surface and the sensor the integration of a multisensor, i.e. a combination of sensors such as X-rays, R-waves and CCDs, and how to insert the obtained data into a linear or non linear model utilizing sufficient information from each sensor the recognition of useful information in softwood scanning. Utilizing electromagnetic wave interaction based sensor data, revealing the latent variables and their variations with respect to quality grading.

  • 36.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Prediction of wood quality features by multivariate models based on scanning techniques1993Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 37.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Produktanpassad virkestorkning: Förbättrad fuktmätning och säkrad produktkvalitet2012Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Projektets syfte är att ta fram kunskap, utveckla metoder och teknik somresulterar i sådana anpassade produktionsprocesser som leder till att produktkvalitet kan definieras i levererade träprodukter. Målsättningen är att anpassa torkningsprocessen utifrån virkets egenskaper så att ökade kvalitetskrav vad gäller fuktinnehåll i specifika slutprodukter säkras. Delresultat av projektet har spridits vid en välbesökt workshop. I detta projekt ska tre konkreta resultat spridas till träindustrin i form av en riktade workshops som visar den simuleringsmodell som ger måluppfyllelse för önskad precision i fuktmätning samt de krav som ställs på process och mätutrustning för att nå dit i den industriella tillämpningen. Ett viktigt resultat i detta projekt är att projektet tillsammans med internationella leverantörer utvärderat existerande in-line fuktkvotsmätare och sedan tillsammans med en av leverantörerna som anslöt till projektet vidareutvecklat kalibreringsmetoder anpassade för industribruk. Det tredje resultatet är kopplat till den nationella dialog och projekt som pågår kring fuktkvot i byggnadsvirke. Ett viktigt delprojekt är att ge en doktorand möjligheten att arbeta med tillämpad FoU i projektet vald teknik. Vi har i projektet valt Mikrovågsbaserad teknik för nästa generation fuktkvotsmätare efter utvärdering. Doktorandens insats är baserat på en egenutvecklade simuleringsmodellen och genomförs med en internationell mätsystemleverantör i samverkan Tekniska Universitet i Wien som utvecklar mikrovågssensorn.

  • 38.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Técnicas de rayos-X e imágenes para la caracterizatión interna y externa de madera2000Konferensbidrag (Övrigt vetenskapligt)
  • 39.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Woodmetrics: imaging devices and processes in wood inspection at Lulea University of Technology1999Ingår i: Polarization and Color Techniques in Industrial Inspection / [ed] Elzbieta A. Marszalec; Emanuele Trucco, SPIE - International Society for Optical Engineering, 1999, s. 148-159Konferensbidrag (Refereegranskat)
    Abstract [en]

    Wood Technology research and education at Lulea University of Technology is located in Skelleftea 800 km north of Stockholm. At the campus about 25 persons are involved in education and research in Wood Technology. We are educating M.Sc. and post- graduate students in Wood Technology. The research at the campus includes the following main fields: -- Wood Machining - - Woodmetrics -- Wood Drying -- Wood Composites/Wood Material Science. Our research strategy is to obtain an individual treatment of every tree, board and piece of wood in order to get highest possible value for the forest products. This shall be accomplished by the aid of advanced scanning technology and computer technology. Woodmetrics means to measure different wood parameters in order to optimize the utilization of the raw material. Today we have the following projects in this field: Automatic wood inspection -- Color changes and moisture flow in drying processes -- Inner quality of logs and lumber - - Stem quality database -- Computer tomography -- Aesthetic properties of wood -- Market/industry/forest relations. In the Woodmetrics field we are using computer tomography, CCD cameras and other sensors in order to find and measure defects in trees and on boards. The signals are analyzed and classified with modern image analyzing techniques and advanced statistical methods.

  • 40.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Woodmetrics: Sensor and knowledge integration in smart wood production systems2003Ingår i: IWSS 5: Proceedings / Fifth international conference on image processing and scanning of wood / [ed] Alfred Rinnhofer, Joanneum research , 2003Konferensbidrag (Övrigt vetenskapligt)
  • 41.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    WQI - a New Zealandish lean, mean and hungry wood quality initiative compared to Swedish initiatives2005Ingår i: Broad spectrum utilisation of wood: proceedings of the COST Action E 44 Conference : June 14th - 15th 2005, Vienna, Austria / [ed] Alfred Teischinger, Wien: Institutes für Holzforschung, Universität für Bodenkultur Wien , 2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes a consortia initiative in New Zealand established to focus on wood quality as a way of enhancing the wood product value, create more valuable forest and get revenue from wood quality tools and IP. Four key research areas has been tailored according to the participants needs supporting solid wood application * Resource characterisation * Improved appearance properties and performance * Improved structural properties and performance * Improved stability and straightness of wood products The idea of the three year program is to * Enhance wood product value by segregation of the resource by quality parameters * Produce a future high performance forest with big and straight trees * Generate Intellectual properties, IP, that support the development of a high technology cluster based on wood quality tools. The NZ, WQI Ltd cluster strategy is compared to similar ones made in the northern part of Sweden, SkeWood, and Träcentrum Norr, TCN. TCN is newly established by the Wood industry, Luleå University of Technology and SP/Trätek institute in terms of strategy, vision and organisation. Skewood is an ongoing academic wood research program with focus areas Wood building, Wood communication and Wood metrics. WQI Ltd and Skewood are analysed after half time in aspects of learning and knowledge building.

  • 42.
    Hagman, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Björngrim, Niclas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Projekt: Smart träbro i smart stad2013Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Smart Träbro i Smart Stad är ett projekt som genom gränsöverskridande samarbete ska ta fram data, modeller och verktyg för att mäta prestanda och kvalitet på en träbrokonstruktion. Genom ett samarbete mellan Luleå Tekniska Universitet (LTU) och Skellefteå kommun skapas exklusiva förutsättningar för att mäta och analysera träkonstruktioner i syfte att stärka konkurrenskraften för trävaruindustrin.

  • 43.
    Hagman, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Broman, Olof
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Popovic, Djordje
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Optimizing the cross cutting operation using research design metod2014Konferensbidrag (Refereegranskat)
  • 44.
    Hagman, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Grundberg, S.A.
    Swedish Institute for Wood Technology Research.
    Classification of scots pine ( Pinus sylvestris ) knots in density images from CT scanned logs1995Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 53, nr 1, s. 75-81Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study was carried out to test methods for separating knots from clearwood in a digital image stack when scanning for internal defects with a medical CT-scanner. Scots pine knots, represented by its tangential surface density image extracted from a CT-image stack, have been classified by two different methods showing equal results. The knots are classified in four knot types by an Artificial Back-propagation Neural Network (ANN) and a Partial Least Squares Modelling with Latent Variables (PLS) model. The classification precision of aim of four different knot types, is between 85% and 97%. The results indicate that both methods may be useful tools in order to describe and classify knots in concentric surfaces around the pith in CT-images and thereby extract parametrical models from CT raw data image stacks. A simplified classification model has been obtained, by analysing the learning patterns in both the ANN and PLS model, that classify knots and transform density related data to segmented and classified parametrical descriptions.

  • 45.
    Hagman, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Grundberg, Stig
    Wang, Xingli
    NTI Norway.
    Sorting pulpwood by X-ray scanning1997Ingår i: 1997 International mechanical pulping conference, Swedish association of pulp and papers engineers , 1997Konferensbidrag (Övrigt vetenskapligt)
  • 46. Hagman, Olle
    et al.
    Grönlund, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Grundberg, Stig
    Accuracy of manual grading: some Swedish experiences1995Ingår i: Caring for the Forest: research in a changing world: congress report : IUFRO XX World Congress, 6-12 August 1995, Tampere, Finland / [ed] Eeva Korpilahti; Heli Mikkelä; Tommi Salonen, 1995Konferensbidrag (Refereegranskat)
  • 47.
    Hagman, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Lundahl, Carl Gustav
    Developing OEE tools for monitoring the sawmill process: A Triple Helix experience?2006Konferensbidrag (Övrigt vetenskapligt)
  • 48.
    Hagman, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Lundgren, Nils
    Predicting physical characteristics of wood by multivariate image projections to latent structures in microwave- and computer tomography images of softwood2004Ingår i: The Forestry Woodchain: Quantifying and forcasting quality from forestry to end product / [ed] Jenny Claridge; Tim Randle, Forest Research, UK , 2004, s. 66-67Konferensbidrag (Övrigt vetenskapligt)
  • 49.
    Hagman, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Nyström, Jan
    Resin pocket detection on surfaces and in 3-d volumes of Norway spruce2003Ingår i: Proceedings of the Fifth International Conference on Image Processing and Scanning of Wood / [ed] Alfred Rinnhofer, Joanneum research Forschungsgesellshaft mbH , 2003, s. 171-176Konferensbidrag (Refereegranskat)
    Abstract [en]

    Resin pockets, common in softwoods, are small lenses of resin oriented along annual rings. When using Norway spruce for making joinery products, resin pockets are considered as serious defect. CT- and RGB-scanning with various illumination were tested for contrast between resin-pockets and other wood properties. UV light in combination with the RGB-sensor showed good possibility to detect resin pockets on open wood surfaces while the other methods showed less contrast between the resin pockets and other wood properties. Segmentation of resin pockets within the 3-D volume was compared for the different sensors using 3-D graphical methods extracting segmentation from 2-D slices of the test piece. The obtained 3-D volumes can be used for investigation of the 3-D spatial representation of resin pockets in spruce.

  • 50.
    Hagman, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Pahlberg, Tobias
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Project: Holonic Integration of Cognition, Communication and Control for a Wood Patching Robot2013Övrigt (Övrig (populärvetenskap, debatt, mm))
12 1 - 50 av 91
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  • rtf