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Antti, Lena
Publications (10 of 28) Show all publications
Vikberg, T., Oja, J. & Antti, L. (2012). Moisture content measurement in Scots pine by microwave and X-rays (ed.). Paper presented at . Wood and Fiber Science, 44(3), 280-285
Open this publication in new window or tab >>Moisture content measurement in Scots pine by microwave and X-rays
2012 (English)In: Wood and Fiber Science, ISSN 0735-6161, Vol. 44, no 3, p. 280-285Article in journal (Refereed) Published
Abstract [en]

There is demand in the Swedish sawmill industry to improve the accuracy of moisture content measurements, both to obtain a better tool to run production and to ensure that the products meet customer expectations. In this study, 240 well-conditioned pieces of Scots pine (Pinus sylvestris), sorted into five different groups by visual inspection, were measured using microwaves and X-rays. Models to predict moisture content of wood were made by measurements of an additional 45 pieces of wood. Using only measured quantities from the microwave system, ie attenuation and phase shift, the root mean square error (RMSE) of the estimated moisture content was 1.00%. By adding total density from the X-ray measurements, RMSE of the estimated moisture content was lowered to 0.89%. Mean errors of the different wood groups varied from -0.65 to 0.18%.

National Category
Bio Materials Other Mechanical Engineering
Research subject
Wood Physics; Wood Technology
Identifiers
urn:nbn:se:ltu:diva-12168 (URN)b41861f7-d32d-495d-9142-d55296fb2d9a (Local ID)b41861f7-d32d-495d-9142-d55296fb2d9a (Archive number)b41861f7-d32d-495d-9142-d55296fb2d9a (OAI)
Note
Validerad; 2012; 20120315 (tomvik)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Antti, L., Finell, M., Arshadi, M. & Lestander, T. A. (2011). Effects of microwave drying on biomass fatty acid composition and fuel pellet quality (ed.). Paper presented at . Wood Material Science & Engineering, 6(1-2), 34-40
Open this publication in new window or tab >>Effects of microwave drying on biomass fatty acid composition and fuel pellet quality
2011 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 6, no 1-2, p. 34-40Article in journal (Refereed) Published
National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-14463 (URN)10.1080/17480272.2010.516369 (DOI)2-s2.0-79953063327 (Scopus ID)dd2dbc20-e731-11df-8b36-000ea68e967b (Local ID)dd2dbc20-e731-11df-8b36-000ea68e967b (Archive number)dd2dbc20-e731-11df-8b36-000ea68e967b (OAI)
Note
Validerad; 2011; 20101103 (lenant)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Antti, L. & Hansson, L. (2010). Equalization of moisture in pre-dried pinewood using microwave power (ed.). Paper presented at . Pro Ligno, 6(2), 53-59
Open this publication in new window or tab >>Equalization of moisture in pre-dried pinewood using microwave power
2010 (English)In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 6, no 2, p. 53-59Article in journal (Refereed) Published
Abstract [en]

Commonly, during air-circulation kiln drying moisture gradients within wood cross-sections are developed, i.e. the surfaces become drier than the interior. To minimize these gradients a conditioning step subsequent to the drying is needed. The aim with this study was to investigate the possibility to use microwave power for equalization of moisture within pinewood boards after air-circulation kiln drying to the average moisture content 0,14. Two dimensions of pinewood were tested; thickness 50 and 63 mm, in two different plants, generating 5 and 12 kW microwave power respectively. Results show that microwave energy give rise to a fast and advantageous moisture equalization within the wood. The higher microwave power density the faster heating and moisture redistribution in these wood dimensions. Required time for heating and redistribution of moisture was found to be as short as 3 minutes at the power density 500 kW/m3. In addition, split-tests indicate decreased or elimination of gap after microwave treatment in the investigated specimens.

Keywords
Forestry, agricultural sciences and landscape planning - Wood fibre and forest products, Skogs- och jordbruksvetenskap samt landskapsplanering - Träfiber- och virkeslära
National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-14916 (URN)e5ac9950-e72e-11df-8b36-000ea68e967b (Local ID)e5ac9950-e72e-11df-8b36-000ea68e967b (Archive number)e5ac9950-e72e-11df-8b36-000ea68e967b (OAI)
Note
Validerad; 2010; 20101103 (lenant)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Antti, L., Finell, M., Arshadi, M. & Lestander, T. (2010). Microwave drying of sawdust: effect on biofuel pellet (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. 313-319). Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Microwave drying of sawdust: effect on biofuel pellet
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. 313-319Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2010
National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-34173 (URN)84a98520-25fd-11df-be83-000ea68e967b (Local ID)84a98520-25fd-11df-be83-000ea68e967b (Archive number)84a98520-25fd-11df-be83-000ea68e967b (OAI)
Conference
International IUFRO Wood Drying Conference : 18/01/2010 - 22/01/2010
Note
Godkänd; 2010; 20100302 (ysko)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Antti, L. & Hansson, L. (2010). Redistribution of moisture in pre-dried pinewood using microwave power: a preliminary study (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. 234-238). Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Redistribution of moisture in pre-dried pinewood using microwave power: a preliminary study
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. 234-238Conference paper, Published paper (Refereed)
Abstract [en]

Commonly, during air-circulation kiln drying moisture gradients within wood cross-sections are developed, i.e. thesurfaces become drier than the interior. To minimize these gradients a conditioning step subsequent to the drying isneeded. The aim with this study was to investigate the possibility to use microwave power for redistribution ofmoisture within pinewood planks after air-circulation kiln drying to the average moisture content 0,14. Twodimensions of pinewood were tested; thickness 50 and 63 mm, in two different plants, generating 5 and 12 kWmicrowave power respectively. Results show that microwave energy give rise to a fast and advantageous moistureredistribution i.e. equalization of moisture content within the wood. The higher microwave power density the fasterheating and moisture equalization in these wood dimensions. Required time for heating and redistribution ofmoisture was found to be as short as 3 minutes at the power density 500 kW/m3. In addition, split-tests indicatedecreased or almost no gap in the investigated specimens.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2010
National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-39093 (URN)db535110-25f5-11df-be83-000ea68e967b (Local ID)db535110-25f5-11df-be83-000ea68e967b (Archive number)db535110-25f5-11df-be83-000ea68e967b (OAI)
Conference
International IUFRO Wood Drying Conference : 18/01/2010 - 22/01/2010
Note
Godkänd; 2010; 20100302 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Hansson, L. & Antti, L. (2008). Modeling microwave heating and moisture redistribution in wood (ed.). Paper presented at . Drying Technology, 26(5), 552-559
Open this publication in new window or tab >>Modeling microwave heating and moisture redistribution in wood
2008 (English)In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 26, no 5, p. 552-559Article in journal (Refereed) Published
Abstract [en]

A finite element model was developed to describe and explain microwave heating of wood and the following moisture redistribution in wood. Dielectric and thermal properties are of great importance, since they are continuously affected during the process by moisture content, density, grain direction, temperature, and more. Computer tomography was used to detect wood density and moisture content. Heat distribution was verified by fiber-optic temperature sensors. The tests were performed in a designed microwave dryer based on 1-kW generators, 2.45GHz. The results show that finite element modeling is a powerful tool to simulate heat and mass transfer in wood, providing the material is well described.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-13183 (URN)10.1080/07373930801944713 (DOI)000254700000007 ()2-s2.0-41949101029 (Scopus ID)c5ec89b0-0f70-11dd-ab53-000ea68e967b (Local ID)c5ec89b0-0f70-11dd-ab53-000ea68e967b (Archive number)c5ec89b0-0f70-11dd-ab53-000ea68e967b (OAI)
Note
Validerad; 2008; 20080421 (pafi)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically 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
Antti, L. & Hansson, L. (2006). Microwave treatment of resinous wood (ed.). In: (Ed.), R. Lagana; S. Kurjatko; J. Kudela (Ed.), Wood structure and properties '06: [proceedings of the 5th IUFRO Symposium Wood Structure and Properties '06 held on September 3-6, 2006 in Sliač - Sielnica, Slovakia]. Paper presented at International Symposium Wood Structure and Properties : 03/09/2006 - 06/09/2006 (pp. 435-437). Zvolen, Slovakia: Arbora Publishers
Open this publication in new window or tab >>Microwave treatment of resinous wood
2006 (English)In: Wood structure and properties '06: [proceedings of the 5th IUFRO Symposium Wood Structure and Properties '06 held on September 3-6, 2006 in Sliač - Sielnica, Slovakia] / [ed] R. Lagana; S. Kurjatko; J. Kudela, Zvolen, Slovakia: Arbora Publishers , 2006, p. 435-437Conference paper, Published paper (Refereed)
Abstract [en]

The output from conventional air-circulation drying of wood is not always satisfying; some individual wood boards often contain somewhat higher moisture content (MC) than the target MC. Higher MC in some pine wood boards after conventional drying could origin from the fact that these contain higher amounts of resin, which may delay or to some extent prevent the moisture flux. It could be the reason to problems in further wood production processes, as for example in gluing processes. The aim of this study was to determine whether or not microwave (MW) heating could be a suitable method to condition these components. Another aim was to investigate if and how migration of resin appears during MW treatment. The study includes experimental tests where determination of both MC and resin content (RC) were carried out before and after MW treatment. Results from the tests show that the RC and the MC are interacting; it means that volumes with high RC also withhold increased amount of moisture; these volumes are often found within boards that origin from the root end of logs. It is possible to dry/condition these planks to reach the target MC within minutes or hours, depending on wood thickness, using MW power. By exposing resinous wood to microwaves, migration of resin takes place from the interior towards the wood surfaces, especially longitudinally through the wood towards the butt ends. It seems to be possible to redistribute RC and MC in wood by exposing only parts of a plank to microwaves.

Place, publisher, year, edition, pages
Zvolen, Slovakia: Arbora Publishers, 2006
National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-38660 (URN)d1c6d8a0-079a-11dc-b09b-000ea68e967b (Local ID)80-968869-4-3 (ISBN)d1c6d8a0-079a-11dc-b09b-000ea68e967b (Archive number)d1c6d8a0-079a-11dc-b09b-000ea68e967b (OAI)
Conference
International Symposium Wood Structure and Properties : 03/09/2006 - 06/09/2006
Note
Godkänd; 2006; 20070521 (cira)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Hansson, L. & Antti, L. (2006). The effect of drying method and temperature level on the hardness of wood (ed.). Paper presented at . Journal of Materials Processing Technology, 171(3), 467-470
Open this publication in new window or tab >>The effect of drying method and temperature level on the hardness of wood
2006 (English)In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 171, no 3, p. 467-470Article in journal (Refereed) Published
Abstract [en]

The purpose of the present work was to investigate whether wood hardness is affected by temperature level during microwave (MW) drying and whether the response is different from that of conventionally dried wood. Matched samples of Norway spruce (Picea abies) were therefore dried from green state to different moisture content (mc) at different temperature levels, both conventionally by air circulation and by MW. The results show that specimens dried by any of the two methods at a temperature level of 100 or 60°C there is a significant difference in wood hardness parallel to the grain between the methods when drying progresses to relatively lower level of moisture content, i.e. wood hardness becomes higher during MW drying. Temperature level in the range 60-110°C during MW drying has no significant influence on wood hardness. Variables such as density and mc have a greater influence on wood hardness than does the drying method or the drying temperature. Since wood is a biological material, its strength varies within the specimens as well as between different samples. For this reason it is important to use matched samples when performing this type of comparative investigation.

National Category
Bio Materials
Research subject
Wood Physics
Identifiers
urn:nbn:se:ltu:diva-16198 (URN)10.1016/j.jmatprotec.2005.08.007 (DOI)000235228900019 ()2-s2.0-30844474006 (Scopus ID)fcbeb2b0-bb52-11db-b560-000ea68e967b (Local ID)fcbeb2b0-bb52-11db-b560-000ea68e967b (Archive number)fcbeb2b0-bb52-11db-b560-000ea68e967b (OAI)
Note
Validerad; 2006; 20061010 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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