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Lundgren, Nils
Publications (10 of 16) Show all publications
Lundgren, N., Ekevad, M. & Flodin, J. (2011). Choosing green sawing dimensions for Norway spruce from stochastic simulations (ed.). Paper presented at . Journal of Wood Science, 57(2), 94-99
Open this publication in new window or tab >>Choosing green sawing dimensions for Norway spruce from stochastic simulations
2011 (English)In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 57, no 2, p. 94-99Article in journal (Refereed) Published
Abstract [en]

The high accuracy of log positioning and the stability of saw blades in breakdown machinery in modern sawmills have reduced the need to add margins for sawing variations. Oversize green sawing dimensions are still needed, but mainly to allow for drying shrinkage. This has put a new focus on better adapting green sawing dimensions to the shrinkage behavior of wood. In this study, a method for optimization of green sawing dimensions using stochastic simulation is presented. Normal distributions were generated for planed dry dimensions, kerf width, and target moisture content. The minimum share of boards exceeding the specified dry dimensions was decided, and deformations in boards from all positions in the cross section in a number of logs were simulated. The simulated shrinkage allowance from stochastic simulations was compared to experimental results from an industry test and to finite element results based on material data for Norway spruce. The results showed that the green width of the sawn boards should increase when the number of boards in the center yield increases. The green thickness of boards should be thinner for center boards and outer boards than for inner boards

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-9009 (URN)10.1007/s10086-010-1142-1 (DOI)000289736400002 ()2-s2.0-79955078449 (Scopus ID)791645a0-bca6-11df-a707-000ea68e967b (Local ID)791645a0-bca6-11df-a707-000ea68e967b (Archive number)791645a0-bca6-11df-a707-000ea68e967b (OAI)
Note
Validerad; 2011; 20100910 (nillun)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ekevad, M., Lundgren, N. & Flodin, J. (2011). Drying shrinkage of sawn timber of Norway spruce (Picea abies): industrial measurements and finite element simulations (ed.). Paper presented at . Wood Material Science & Engineering, 6(1-2), 41-48
Open this publication in new window or tab >>Drying shrinkage of sawn timber of Norway spruce (Picea abies): industrial measurements and finite element simulations
2011 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 6, no 1-2, p. 41-48Article in journal (Refereed) Published
Abstract [en]

Industrial measurements of green and dry cross-section dimensions were performed for 189 Norway spruce (Picea abies) centre-yield boards with dry dimensions 51 times 149 mm. Two, three or four boards were sawn from each log, depending on log size. Different approaches were used for simulations of cross-section shrinkage during drying. An analytical model, an elastic, an elastic- mechanosorptive and an elastic- plastic finite element simulation model were tested. Thickness and width shrinkage and deformation were simulated. Shrinkage results were compared with each other and with the experimental results. All simulation models gave roughly the same degree of agreement with experimental results except for the centre board from the three-board sawing pattern. For the other boards, the analytical model was not generally better or worse than the results from the finite element models. Shrinkage deformations in finite element models that included mechanosorption or plasticity were nearly the same as for the elastic finite element model except for the centre board of the three-board sawing pattern. The mechanosorptive model was the best model for the shrinkage of the centre board of this sawing pattern except for mid-thickness shrinkage. Comparison between the different finite element simulation models of stresses in the centre board revealed large differences.

Keywords
Materials science - Construction materials, Teknisk materialvetenskap - Konstruktionsmaterial
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-15958 (URN)10.1080/17480272.2010.523121 (DOI)2-s2.0-79953033534 (Scopus ID)f8a308a0-d1ee-11df-a707-000ea68e967b (Local ID)f8a308a0-d1ee-11df-a707-000ea68e967b (Archive number)f8a308a0-d1ee-11df-a707-000ea68e967b (OAI)
Note
Validerad; 2011; 20101007 (matse)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ekevad, M., Lundgren, N. & Flodin, J. (2010). Choosing green sawing dimensions for best value yield of Norway spruce: industrial measurements and physical modelling (ed.). In: (Ed.), Tom Morén; Lena Antti; Margot Sehlstedt-Persson (Ed.), Proceedings, 11th International IUFRO Wood Drying Conference: [... in Skellefteå, Sweden, January 18 - 22, 2010 ... the theme of the conference was "Recent Advances in the Field of Wood Drying"]. Paper presented at International IUFRO Wood Drying Conference : 18/01/2010 - 22/01/2010 (pp. 168-174). Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Choosing green sawing dimensions for best value yield of Norway spruce: industrial measurements and physical modelling
2010 (English)In: Proceedings, 11th International IUFRO Wood Drying Conference: [... in Skellefteå, Sweden, January 18 - 22, 2010 ... the theme of the conference was "Recent Advances in the Field of Wood Drying"] / [ed] Tom Morén; Lena Antti; Margot Sehlstedt-Persson, Luleå: Luleå tekniska universitet, 2010, p. 168-174Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2010
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-27627 (URN)121479a0-0764-11df-bae5-000ea68e967b (Local ID)121479a0-0764-11df-bae5-000ea68e967b (Archive number)121479a0-0764-11df-bae5-000ea68e967b (OAI)
Conference
International IUFRO Wood Drying Conference : 18/01/2010 - 22/01/2010
Note
Godkänd; 2010; 20100122 (matse)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
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
Show others...
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
Lundgren, N., Gerasimov, V., Kozlova, T. & Zorin, E. (2007). An online microwave scanner for sawn wood (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>An online microwave scanner for sawn wood
2007 (English)Report (Other academic)
Abstract [en]

This article presents the results from preliminary tests of a microwave scanner. The ability to measure variations in density and moisture content (MC) has been related to results from previous measurements using the same type of sensor. Density variations gave a response that was similar to the response from the old sensor. Variations in moisture content were too small in each piece to be separated from measurement noise. The results show that the main benefit with the new sensor is increased scanning speed.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2007. p. 7
Series
Technical report / Luleå University of Technology, ISSN 1402-1536 ; 2007:04
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-22916 (URN)4cee3a50-d3d4-11db-b6e3-000ea68e967b (Local ID)4cee3a50-d3d4-11db-b6e3-000ea68e967b (Archive number)4cee3a50-d3d4-11db-b6e3-000ea68e967b (OAI)
Note
Godkänd; 2007; 20070316 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Lundgren, N. (2007). Microwave sensors for scanning of sawn timber (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Microwave sensors for scanning of sawn timber
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A microwave imaging sensor that measures the signal transmitted through a board was investigated with respect to the ability to predict the distribution of moisture and density in sawn lumber. Furthermore, the response from the sensor was related to strength properties of the boards. Multivariate statistics was used to relate the measured variables to various properties. A finite element model based on X-ray computed tomography images was developed to describe the interactions between microwaves and wood. The model made it possible to simulate the response from the sensor under varying conditions. The results show that microwaves can be used for prediction of density and moisture content. They can also be used for prediction of strength properties, mainly from the correlation to density, but also from the influence on microwaves of structural variations in the wood. The finite element model is useful in the evaluation of microwave sensors for wood, drying equipment or other applications where electromagnetic waves interact with wood.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2007. p. 40
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544 ; 2007:09
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-17598 (URN)43b33b80-e1ed-11db-b0f8-000ea68e967b (Local ID)43b33b80-e1ed-11db-b0f8-000ea68e967b (Archive number)43b33b80-e1ed-11db-b0f8-000ea68e967b (OAI)
Note
Godkänd; 2007; 20070403 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Lundgren, N. & Hansson, L. (2007). PLS models for predicting wood properties from microwave measurements based on three dimensional FEM simulations (ed.). In: (Ed.), Helena Johnsson (Ed.), Proceedings from the Nordic Workshop in Wood Engineering: . Paper presented at Nordic Workshop in Wood Engineering : 21/02/2007 - 21/02/2007. Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>PLS models for predicting wood properties from microwave measurements based on three dimensional FEM simulations
2007 (English)In: Proceedings from the Nordic Workshop in Wood Engineering / [ed] Helena Johnsson, Luleå: Luleå tekniska universitet, 2007Conference paper, Published paper (Other academic)
Abstract [en]

When electromagnetic waves propagate through wood they will be affected by variations in the dielectric properties. These variations are related to different properties within the wood. Dielectric properties of wood depend on moisture content, density, temperature, grain angle and frequency of the electromagnetic wave. The aim with this study was to use threedimensional finite element modelling (FEM) in combination with multivariate statistics and projection to latent structures (PLS) to develop a prediction model for moisture content and dry basis density in wood. An X-ray computed tomography (CT) scanner was used to detect density and, with that, moisture content in wood. Dielectric properties were calculated within a wood volume and used in the simulation. Different frequencies and directions of the electric field were simulated. Previous studies have shown that this method gives a good description of the interactions between wood and microwaves in two dimensions. The results show that 3D finite element modelling can be used to generate a prediction model for moisture content from microwave scanning. Other properties of wood such as density and grain angle have less influence on the microwaves but might be predicted by further processing of the signal.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2007
Series
Research report / Luleå University of Technology, ISSN 1402-1528 ; 2007:06
National Category
Other Mechanical Engineering Bio Materials
Research subject
Wood Technology; Wood Physics
Identifiers
urn:nbn:se:ltu:diva-32796 (URN)765b7e80-d3c4-11db-b6e3-000ea68e967b (Local ID)765b7e80-d3c4-11db-b6e3-000ea68e967b (Archive number)765b7e80-d3c4-11db-b6e3-000ea68e967b (OAI)
Conference
Nordic Workshop in Wood Engineering : 21/02/2007 - 21/02/2007
Note
Godkänd; 2007; 20070316 (ysko)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Lundgren, N., Brännström, M., Hagman, O. & Oja, J. (2007). Predicting the strength of Norway spruce by microwave scanning: a comparison with other scanning techniques (ed.). Paper presented at . Wood and Fiber Science, 39(1), 167-172
Open this publication in new window or tab >>Predicting the strength of Norway spruce by microwave scanning: a comparison with other scanning techniques
2007 (English)In: Wood and Fiber Science, ISSN 0735-6161, Vol. 39, no 1, p. 167-172Article in journal (Refereed) Published
Abstract [en]

In this study, 90 boards of Norway spruce (Picea abies (L.) Karst.) sized 48 x 148 mm in cross-section, have been examined using different scanning and measurement techniques. All of the boards originated from a sawmill located in southern Finland. Planar X-ray scanning, microwave scanning, and grain-angle measurement have been performed. In addition, strength and elastic properties were assessed for eachpiece by four point bending. The purpose of the study was to relate the potential of microwave scanning compared to other, industrially available techniques and to explain the physiological background of the microwave responses. The results show that the microwave signal, after transmission through wood, contains information about the bending strength and the modulus of elasticity. The correlation to densityis a key factor. Annual ring width was also found to be correlated both to microwave measurements and strength properties.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-9596 (URN)83ed8810-0388-11dc-8b31-000ea68e967b (Local ID)83ed8810-0388-11dc-8b31-000ea68e967b (Archive number)83ed8810-0388-11dc-8b31-000ea68e967b (OAI)
Note
Validerad; 2007; 20070516 (nillun)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Lundgren, N., Hansson, L., Hagman, O. & Antti, L. (2006). FEM simulation of interactions between microwaves and wood during thawing (ed.). In: (Ed.), Börje Nilsson; Louis Fishman (Ed.), Mathematical modeling of wave phenomena: conference on mathematical modeling of wave phenomea, Växjö, Sweden, 14 - 19 August 2005. Paper presented at Conference on Mathematical Modeling of Wave Phenomena : 14/08/2005 - 19/08/2005 (pp. 260-267). Melville, NY: American Institute of Physics (AIP)
Open this publication in new window or tab >>FEM simulation of interactions between microwaves and wood during thawing
2006 (English)In: Mathematical modeling of wave phenomena: conference on mathematical modeling of wave phenomea, Växjö, Sweden, 14 - 19 August 2005 / [ed] Börje Nilsson; Louis Fishman, Melville, NY: American Institute of Physics (AIP), 2006, p. 260-267Conference paper, Published paper (Refereed)
Abstract [en]

Dipole polarization of water molecules is an important factor when microwaves interact with moist wood. Hence there will be a considerable change in dielectric properties when the wood changes from frozen to nonfrozen condition. The aim of this study was to develop a model that simulates measurements with a microwave scanner based on a sensor working at 9.4 GHz. Two-dimensional finite element modelling (FEM) was implemented to analyze interactions between microwaves and green wood during thawing of frozen wood at room temperature. A medical computed tomography scanner was used to measure the internal structure of density in a piece of wood in green and dry condition. From these density images the distribution of dry weight moisture content was calculated for a cross section of the piece and used in the model. Images describing the distribution of the electric field and phase shift at different temperatures where obtained from the FEM simulation. The results show that simulated values correspond well to measured values. This confirms that the model presented in this study is a useful tool to describe the interaction between microwaves and wood during microwave scanning at varying conditions.

Place, publisher, year, edition, pages
Melville, NY: American Institute of Physics (AIP), 2006
Series
A I P Conference Proceedings Series, ISSN 0094-243X ; 834
National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-27355 (URN)10.1063/1.2205809 (DOI)33845595253 (Scopus ID)0c78bb20-8d3a-11db-8975-000ea68e967b (Local ID)0-7354-0325-2 (ISBN)0c78bb20-8d3a-11db-8975-000ea68e967b (Archive number)0c78bb20-8d3a-11db-8975-000ea68e967b (OAI)
Conference
Conference on Mathematical Modeling of Wave Phenomena : 14/08/2005 - 19/08/2005
Note
Validerad; 2006; 20061215 (ysko)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Hansson, L., Antti, L., Lundgren, N. & Hagman, O. (2006). Finite element modeling (FEM) simulation of interactions between wood and microwaves (ed.). Paper presented at . Journal of Wood Science, 52(5), 406-410
Open this publication in new window or tab >>Finite element modeling (FEM) simulation of interactions between wood and microwaves
2006 (English)In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 52, no 5, p. 406-410Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to use finite element modeling (FEM) as a tool to analyze microwave scattering in wood and to verify the model by measurements with a microwave scanner. A medical computed tomography scanner was used to measure distribution of density and moisture content in a piece of Scots pine (Pinus sylvestris). Dielectric properties were calculated from measured values for cross sections from the piece and used in the model. Images describing the distribution of the electric field and phase shift were obtained from the FEM simulation. The model was verified by measurements with a scanner based on a microwave sensor. The results show that simulated values correspond well to measured values. Furthermore, discontinuities in the material caused scattering in both the measured and the simulated values. The greater the discontinuity in the material, the greater was the need for computational power in the simulation.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-16146 (URN)10.1007/s10086-005-0794-8 (DOI)000241010600006 ()2-s2.0-33749443195 (Scopus ID)fbcca700-bb51-11db-b560-000ea68e967b (Local ID)fbcca700-bb51-11db-b560-000ea68e967b (Archive number)fbcca700-bb51-11db-b560-000ea68e967b (OAI)
Note
Validerad; 2006; 20061017 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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