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Nyström, Jan
Publications (10 of 21) Show all publications
Grönlund, A., Flodin, J., Vikberg, T., Nyström, J. & Lundgren, N. (2009). Monitoring lumber size, shape and mismatch in double-arbour saws-Development and validation of scanning equipment (ed.). In: (Ed.), Handong Zhou; Nanfeng Zhu; Tao Ding (Ed.), Proceedings of the 19th International Wood Machining Seminar: . Paper presented at International Wood Machining Seminar : 23/10/2009 - 23/10/2009 (pp. 222-227). Nanjing: Nanjing Forestry University
Open this publication in new window or tab >>Monitoring lumber size, shape and mismatch in double-arbour saws-Development and validation of scanning equipment
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2009 (English)In: Proceedings of the 19th International Wood Machining Seminar / [ed] Handong Zhou; Nanfeng Zhu; Tao Ding, Nanjing: Nanjing Forestry University , 2009, p. 222-227Conference paper, Published paper (Refereed)
Abstract [en]

The costs for raw material amount to about 70% of the total costs for most sawmills. Consequently, it is very important to improve the saw yield for the economy and competitiveness of sawmills. The aim of an ongoing project in Sweden is to build knowledge and develop methods and techniques that enable an increase of the sawing yield. The idea is that the yield increase will be achieved through thinner kerfs, adapted shrinkage allowance and lower sawing allowance. One key parameter in the sawing process is sawing accuracy. We have as a part of the ongoing project developed scanning equipment with which we can measure the size and geometry of the produced lumber. The equipment is an off line research apparatus based on two laser triangulation devices.The industrial partners on the project have especially pointed out that a method is needed for measurement and evaluation of the mismatch on sawn surfaces produced by double arbour saw machines. The equipment has a measurement resolution that is better than 0.1 mm in the thickness direction and can measure thickness and width with a repeatability of 0.1 mm and bow, crook, twist and cup with a repeatability of < 1 mm. As there is no standard for measurement and evaluation of mismatch, a special algorithm for this parameter has been developed and correlated against subjective judgements of skilled personnel from the sawmill industry. The correlation between manually judged mismatch and mismatch measured by the scanner was 0.76.

Place, publisher, year, edition, pages
Nanjing: Nanjing Forestry University, 2009
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-32237 (URN)6a99cad0-a917-11df-a707-000ea68e967b (Local ID)978-7-5023-6224-9 (ISBN)6a99cad0-a917-11df-a707-000ea68e967b (Archive number)6a99cad0-a917-11df-a707-000ea68e967b (OAI)
Conference
International Wood Machining Seminar : 23/10/2009 - 23/10/2009
Note
Godkänd; 2009; 20100816 (andbra)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Nyström, J., Oja, J. & Broman, O. (2008). Modelling the connection between industrially measured raw material properties and end user preferences: Part 1. The simulation tool (ed.). In: (Ed.), H. Peltola (Ed.), Connection between Forest Resources and Wood Quality: Modelling Approaches and Simulation Software. IUFRO Working Party 5.01.04 Wood Quality Modelling, June 8. - 14, Koli, Finland. Paper presented at IUFRO Workshop on 'Connection between Forest Resources and Wood Quality : Modelling Approaches and Simulation Software 08/06/2008 - 14/06/2008.
Open this publication in new window or tab >>Modelling the connection between industrially measured raw material properties and end user preferences: Part 1. The simulation tool
2008 (English)In: Connection between Forest Resources and Wood Quality: Modelling Approaches and Simulation Software. IUFRO Working Party 5.01.04 Wood Quality Modelling, June 8. - 14, Koli, Finland / [ed] H. Peltola, 2008Conference paper, Published paper (Other academic)
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-31017 (URN)50e280f0-e316-11dd-981b-000ea68e967b (Local ID)50e280f0-e316-11dd-981b-000ea68e967b (Archive number)50e280f0-e316-11dd-981b-000ea68e967b (OAI)
Conference
IUFRO Workshop on 'Connection between Forest Resources and Wood Quality : Modelling Approaches and Simulation Software 08/06/2008 - 14/06/2008
Note
Godkänd; 2008; 20090115 (ysko)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Broman, O., Nyström, J. & Oja, J. (2008). Modelling the connection between industrially measured raw material properties and end user preferences: Part 2. Results from preference studies (ed.). In: (Ed.), H. Peltola (Ed.), Connection between Forest Resources and Wood Quality: Modelling Approaches and Simulation Software. IUFRO Working Party 5.01.04 Wood Quality Modelling, June 8. - 14, Koli, Finland. Paper presented at IUFRO Workshop on 'Connection between Forest Resources and Wood Quality : Modelling Approaches and Simulation Software 08/06/2008 - 14/06/2008.
Open this publication in new window or tab >>Modelling the connection between industrially measured raw material properties and end user preferences: Part 2. Results from preference studies
2008 (English)In: Connection between Forest Resources and Wood Quality: Modelling Approaches and Simulation Software. IUFRO Working Party 5.01.04 Wood Quality Modelling, June 8. - 14, Koli, Finland / [ed] H. Peltola, 2008Conference paper, Published paper (Other academic)
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-40049 (URN)f05c1630-e318-11dd-981b-000ea68e967b (Local ID)f05c1630-e318-11dd-981b-000ea68e967b (Archive number)f05c1630-e318-11dd-981b-000ea68e967b (OAI)
Conference
IUFRO Workshop on 'Connection between Forest Resources and Wood Quality : Modelling Approaches and Simulation Software 08/06/2008 - 14/06/2008
Note
Godkänd; 2008; 20090115 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Oja, J., Broman, O. & Nyström, J. (2008). Modelling the connection between industrially measured raw material properties and end user preferences: Part 3. Optimizing the industrial production (ed.). In: (Ed.), H. Peltola (Ed.), Connection between Forest Resources and Wood Quality: Modelling Approaches and Simulation Software. IUFRO Working Party 5.01.04 Wood Quality Modelling, June 8. - 14, Koli, Finland. Paper presented at IUFRO Workshop on 'Connection between Forest Resources and Wood Quality : Modelling Approaches and Simulation Software 08/06/2008 - 14/06/2008.
Open this publication in new window or tab >>Modelling the connection between industrially measured raw material properties and end user preferences: Part 3. Optimizing the industrial production
2008 (English)In: Connection between Forest Resources and Wood Quality: Modelling Approaches and Simulation Software. IUFRO Working Party 5.01.04 Wood Quality Modelling, June 8. - 14, Koli, Finland / [ed] H. Peltola, 2008Conference paper, Published paper (Other academic)
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-32031 (URN)6648fd90-e319-11dd-981b-000ea68e967b (Local ID)6648fd90-e319-11dd-981b-000ea68e967b (Archive number)6648fd90-e319-11dd-981b-000ea68e967b (OAI)
Conference
IUFRO Workshop on 'Connection between Forest Resources and Wood Quality : Modelling Approaches and Simulation Software 08/06/2008 - 14/06/2008
Note
Godkänd; 2008; 20090115 (ysko)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Broman, O., Nyström, J. & Oja, J. (2007). Effektiv produktion av golvprodukter med krav på estetiska egenskaper (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Effektiv produktion av golvprodukter med krav på estetiska egenskaper
2007 (Swedish)Report (Other academic)
Alternative title[en]
Efficient production of Solid wood flooring with consumer demands on aesthetic features
Abstract [sv]

Trä används i många tillämpningar där träet är synligt och där råvarans estetiska egenskaper därför är mycket. Exempel på sådana tillämpningar är produkter är golv och paneler. I detta projekt har produktionsprocessen för solida furugolv studerats, det vill säga hela kedjan från sortering av stockar till slutkonsumenters preferenser. Samarbetspartners i detta FoU- projekt har varit SCA -Bollsta sågverk, Norrlands Trä AB, SP Trätek och LTU - Träteknologi, Skellefteå. Syftet med projektet har varit att demonstrera hur man med hjälp av modern marknadsanalys, modern, industriellt implementerad mätteknik och avancerade sorteringsalgoritmer kan effektivisera produktionen av kundanpassade produkter med krav på estetiska egenskaper. Ett delmål var att undersöka alternativa utseendekvaliteter till dagens produktion av golvträ. Den genomgående metoden har varit att mäta och dokumentera råvarans egenskaper genom hela processen från stock till färdig produkt. En lättanvänd interaktiv databas har utvecklats inom ramen för projektet och använts för simulering av alternativa sorteringar av råvara avsedd för golvproduktion. Kopplat till databasen har även ett visualiseringsverktyg utvecklats. Detta gör det möjligt att direkt kunna se resultatet av simuleringarna i form av digitala golvytor. Utöver resultat i form av utvecklad databasgränssnitt, visualiseringsverktyg och verktyg för konsumentudersökningar så har projektet visat på intressanta resultat vad gäller både produktions och marknad. Resultatet av databassimuleringarna visar att man genom att förändra sorteringsstrategin och sortera stockarna baserat på information från en röntgenmätram helt kan undvika utsortering i råsorteringen, minska utsorteringen i justerverket med 25% (från tolv till nio procentenheter) och ändå producera en golvråvara med samma estetiska egenskaper som tidigare. Som ett alternativ till den ursprungliga golvråvaran har även en ny golvråvara definierats. Preferensstudier i både Sverige och Norge visade att konsumenternas tyckte bättre om den nya kvaliteten än den utsprungliga. Samtidigt gjorde denna nya golvråvara det möjligt att helt undvika utsortering i både råsortering och justerverk och samtidigt öka den tillgängliga golvråvaran med 27% (från 30 till 38 procentenheter).

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2007. p. 65
Series
Technical report / Luleå University of Technology, ISSN 1402-1536 ; 2007:09
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-22133 (URN)1a98d0f0-5148-11dc-959a-000ea68e967b (Local ID)1a98d0f0-5148-11dc-959a-000ea68e967b (Archive number)1a98d0f0-5148-11dc-959a-000ea68e967b (OAI)
Note
Godkänd; 2007; 20070823 (olof)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Nyström, J. & Grundberg, S. (2007). Industrial measurement of spiral grain on debarked sawlogs and prediction of twist on centre planks after drying (ed.). In: (Ed.), Joris Van Acker; Arto Usenius (Ed.), Modelling the Wood Chain: Forestry - Wood Industry - Wood Products Markets. Paper presented at Modelling the Wood Chain : 17/09/2007 - 19/09/2007 (pp. 87-93). Ghent: Ghent University
Open this publication in new window or tab >>Industrial measurement of spiral grain on debarked sawlogs and prediction of twist on centre planks after drying
2007 (English)In: Modelling the Wood Chain: Forestry - Wood Industry - Wood Products Markets / [ed] Joris Van Acker; Arto Usenius, Ghent: Ghent University , 2007, p. 87-93Conference paper, Published paper (Refereed)
Abstract [en]

Spiral grain occurs naturally more or less in all trees. Instead of running parallel to the pith, the grain runs spiralled around the trunk like a helix. Since wood is an orthotropic material with higher shrinkage perpendicular to than parallel with the grain, the tree will twist when dried, and so will a plank or board cut from it. The tracheid effect utilizes the light-conducting properties of the softwood tracheids to measure the direction of spiral grain. A small laser point was projected on the wood surface. The light transmitted in the wood and scattered back forms an elliptic shape extended in the direction of the fibres. The ellipse of light was registered with a CMOS camera and the orientation of the ellipse's major axis was computed by image processing in real time. A camera system for measuring spiral grain on the debarked surface of a log was installed at a sawmill. In normal production, centre planks of Norway spruce were marked with colour in six different groups according to the size and direction of spiral grain measured by the camera system. All marked planks were manually measured for twist after drying. Measurements on 843 pieces show a coefficient of determination of 0.76 between spiral grain under bark and twist after drying.

Place, publisher, year, edition, pages
Ghent: Ghent University, 2007
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-40454 (URN)f98c6050-c052-11dc-b185-000ea68e967b (Local ID)9789080656536 (ISBN)f98c6050-c052-11dc-b185-000ea68e967b (Archive number)f98c6050-c052-11dc-b185-000ea68e967b (OAI)
Conference
Modelling the Wood Chain : 17/09/2007 - 19/09/2007
Note

Godkänd; 2007; 20080111 (jannys)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-02-26Bibliographically approved
Grönlund, A., Oja, J., Grundberg, S., Nyström, J. & Ekevad, M. (2007). Process control based on measurement of spiral grain and heartwood content (ed.). In: (Ed.), (Ed.), Proceeding of 18th International Wood Machining Seminar: IWMS 18. Paper presented at International Wood Machining Seminar : 07/05/2007 - 09/05/2007.
Open this publication in new window or tab >>Process control based on measurement of spiral grain and heartwood content
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2007 (English)In: Proceeding of 18th International Wood Machining Seminar: IWMS 18, 2007Conference paper, Published paper (Refereed)
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-39048 (URN)da3dbce0-943c-11dc-b13a-000ea68e967b (Local ID)da3dbce0-943c-11dc-b13a-000ea68e967b (Archive number)da3dbce0-943c-11dc-b13a-000ea68e967b (OAI)
Conference
International Wood Machining Seminar : 07/05/2007 - 09/05/2007
Note
Godkänd; 2007; 20071116 (matse)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Ekevad, M., Salin, J.-G., Grundberg, S., Nyström, J. & Grönlund, A. (2006). Modelling of adequate pretwist for obtaining straight timber (ed.). Paper presented at . Wood Material Science & Engineering, 1(2), 76-84
Open this publication in new window or tab >>Modelling of adequate pretwist for obtaining straight timber
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2006 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 1, no 2, p. 76-84Article in journal (Refereed) Published
Abstract [en]

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic-ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-12162 (URN)10.1080/17480270600977872 (DOI)2-s2.0-77950465887 (Scopus ID)b3ef9870-8eb9-11dc-a188-000ea68e967b (Local ID)b3ef9870-8eb9-11dc-a188-000ea68e967b (Archive number)b3ef9870-8eb9-11dc-a188-000ea68e967b (OAI)
Note
Validerad; 2006; 20071109 (matse)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Grönlund, A., Grundberg, S., Oja, J. & Nyström, J. (2005). Scanning techniques as tools for integration in the wood conversion chain: some industrial applications (ed.). In: (Ed.), Alfred Teischinger (Ed.), Broad spectrum utilisation of wood: proceedings of the COST Action E 44 Conference : June 14th - 15th 2005, Vienna, Austria. Paper presented at COST Action E 44 Conference : 14/06/2005 - 15/06/2005. Wien: Institutes für Holzforschung, Universität für Bodenkultur Wien
Open this publication in new window or tab >>Scanning techniques as tools for integration in the wood conversion chain: some industrial applications
2005 (English)In: 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 , 2005Conference paper, Published paper (Refereed)
Abstract [en]

The market makes lot of different demands on sawn wood products. There are requirements regarding strength, straightness, durability, aesthetic appearance, etc. Most of these demands can be fulfilled by the inherent properties of the trees in the forest. The challenge is to utilize the wood properties to fulfil the market demands in an efficient way. The raw material has to be selected so every customer gets the right piece of wood with the required properties. In order to achieve this, the raw material has to be characterized with different scanning techniques in several steps before and during the breakdown process. In this presentation some examples and experiences from industrially implemented scanning techniques will be described. We can today, after some years of R&D efforts, see how X-ray LogScanners are implemented in the industry. So far they are used for measurement of diameter under bark, internal knot structure, annual ring width, heartwood content and commodity grades. The full potential of this technique is, however, not being fully utilized yet. Equipment for measurement of spiral grain on logs and sawn wood has also been implemented industrially. It has been proven that with the aid of this equipment boards that will twist during drying can be sorted out and treated separately, thus enabling production of straighter timber. The third type of equipment that will be presented is a heartwood scanner. With this scanner, sawmills select Scots pine planks with high heartwood content that are suitable for applications where improved durability is required. These examples show that scanning technology is a key factor for a successful integration between market and forest.

Place, publisher, year, edition, pages
Wien: Institutes für Holzforschung, Universität für Bodenkultur Wien, 2005
Series
Lignovisionen ; 9
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-38165 (URN)c7ad4110-0646-11dc-b09b-000ea68e967b (Local ID)c7ad4110-0646-11dc-b09b-000ea68e967b (Archive number)c7ad4110-0646-11dc-b09b-000ea68e967b (OAI)
Conference
COST Action E 44 Conference : 14/06/2005 - 15/06/2005
Note
Godkänd; 2005; 20070519 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Nyström, J. (2003). Automatic measurement of fiber orientation in softwoods by using the tracheid effect (ed.). Paper presented at . Computers and Electronics in Agriculture, 41(1-3), 91-99
Open this publication in new window or tab >>Automatic measurement of fiber orientation in softwoods by using the tracheid effect
2003 (English)In: Computers and Electronics in Agriculture, ISSN 0168-1699, E-ISSN 1872-7107, Vol. 41, no 1-3, p. 91-99Article in journal (Refereed) Published
Abstract [en]

Spiraled grain commonly occurs in softwood trees. Instead of running parallel to the pith, the grain runs spirally around the trunk like a helix. Since wood is an orthotropic material with higher shrinkage perpendicular to than parallel to the fibers, the log will twist when dried, and so will a plank or board cut from it. Several investigations have shown that the magnitude of twist in sawn wood is highly correlated to the fiber orientation, so by measuring the fiber orientation on green lumber, the risk of warp after drying can be indicated. Fiber orientation is also interesting for other purposes, for example stress grading and research applications. We concern the tracheid effect, which utilizes the light conducting properties of the softwood tracheids to measure fiber orientation. A small circular laser beam was projected onto the wood surface. The light was transmitted in the wood and scattered back to form an elliptical shape extended in the direction of the fibers. The ellipse of light was registered with a CMOS camera, and the orientation of the ellipse's major axis was calculated. This method has a correlation coefficient of 0.99996 to manually aligned fiber orientation, and repeated measurements show a standard deviation of 0.2°. Calculation time for one 64×64 pixel image was 67 μs, which must be regarded as useful for industrial applications

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-14087 (URN)10.1016/S0168-1699(03)00045-0 (DOI)000186588800008 ()2-s2.0-0142035289 (Scopus ID)d68001e0-bb51-11db-b560-000ea68e967b (Local ID)d68001e0-bb51-11db-b560-000ea68e967b (Archive number)d68001e0-bb51-11db-b560-000ea68e967b (OAI)
Note
Validerad; 2003; 20061025 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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