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Sehlstedt-Persson, M., Hansson, L., Couceiro, J. & Vikberg, T. (2019). Konditionering av virke vid olika fuktkvoter: studier i tomograf. Skellefteå
Open this publication in new window or tab >>Konditionering av virke vid olika fuktkvoter: studier i tomograf
2019 (Swedish)Report (Other academic)
Abstract [sv]

Fuktförändringar i virke under pågående konditionering har aldrig tidigare studerats i tomograf.

Resultat av denna labbstudie av diffusionsbaserad, icke-kondenserande jämviktskonditionering vid olika fuktkvotsnivåer sammanfattas enligt följande: (Notera att torkningsspänningar inte utvärde­rats i denna studie utan enbart fuktförändringar.)

  • Studien styrker industriella erfarenheter att konditionering ”tar bättre” på virke nedtorkat till lägre fuktkvot jämfört än om fuktkvoterna är högre.
  • Försöken ger en god fingervisning om hur länge konditionering bör pågå för en viss önskad medel­fuktkvotshöjning i ett industriellt vanligt förekommande klimat 70 °C och psykrometer­skillnad 2° vilket motsvarar en jämviktsfuktkvot på 16,8%. Vill man ex höja medelfuktkvoten från 10 – 12% visar resultaten att 4 timmars konditionering är tillräckligt för furuvirket. Att i samma klimat höja medel­fuktkvoten 2% vid högre startfuktkvoter (mellan 14–23%) har inte i något fall varit möjligt för vare sig gran eller furu under de 8 timmar som konditionering pågick. Det är också viktigt att påpeka att konditioneringsklimatet i dessa labbförsök har uppnått börvärden mycket snabbt (figur 3) vilket inte är fallet vid stora virkeslaster i industriskala där basningskapacitet och blåsdjup påverkar tid till uppnådda börvärden.
  • Vad gäller fuktkvotsskillnad nära ytorna ses generellt en utplaning av fuktförändringar i samtliga försök efter 3–4 timmar.
  • Fuktkvotsnivån spelar roll för den inledande fuktkvotsförändringen inom tvärsnittet: ju torrare virke desto snabbare förändring.
  • När konditioneringen startar är fuktvandringen i splintved effektivare än i kärnved vilket sannolikt förklaras av splintvedens högre diffusivitet.
  • Vad gäller eventuella skillnad mellan träslag är det inte möjligt att dra några slutsatser.
  • Metodstudien visar att upplösningen i tomografen är tillräcklig för att kunna utvärdera fuktkvotsförändringar nära virkesytorna i ca 3 mm tjocka skal.
Place, publisher, year, edition, pages
Skellefteå: , 2019. p. 28
Series
TräCentrumNorr
Keywords
trä, furu, gran, tomografi, torkning, konditionering
National Category
Engineering and Technology Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-72978 (URN)
Projects
”TiiN, TräInnovation i Norr”
Funder
Swedish Agency for Economic and Regional Growth
Note

Denna studie har utförts i projektet "Utveckling av industriell virkestorkning" inom ramen för projektet ”TiiN, TräInnovation i Norr”  

Available from: 2019-02-21 Created: 2019-02-21 Last updated: 2019-02-28Bibliographically approved
Couceiro, J., Lindgren, O., Hansson, L., Söderström, O. & Sandberg, D. (2019). Real-time wood moisture-content determination using dual-energy X-ray computed tomography scanning. Wood Material Science & Engineering
Open this publication in new window or tab >>Real-time wood moisture-content determination using dual-energy X-ray computed tomography scanning
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2019 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280Article in journal (Refereed) Epub ahead of print
Abstract [en]

The estimation of the pixel-wise distribution of the moisture content (MC) in wood using X-ray computed tomography (CT) requires two scans of the same wood specimen at different MCs, one of which is known. Image-processing algorithms are needed to compensate for the anisotropic distortion that wood undergoes as it dries. An alternative technique based on dual-energy CT (DECT) to determine MC in wood has been suggested by several authors. The purpose of the present study was to evaluate the hypothesis that DECT can be used for the determination of MC in real time. A method based on the use of the quotient between the linear attenuation coefficients (μ) at different acceleration voltages (the so-called quotient method) was used. A statistical model was created to estimate the MC in solid sapwood of Scots pine, Norway spruce and brittle willow. The results show a regression model with R2 > 0.97 that can predict the MC in these species with a RMSE of prediction of 0.07, 0.04 and 0.11 (MC in decimal format) respectively and at MC levels ranging from the green to the totally dry condition. Individual measurements of MC show an uncertainty of up to ±0.4. It is concluded that under the conditions prevailing in this study, and in studies referred to in this paper, it is not possible to measure MC with DECT.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
CT-scanning, dual-energy X-ray absorptiometry, wood drying, attenuation coefficient
National Category
Wood Science Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-75497 (URN)10.1080/17480272.2019.1650828 (DOI)000480865200001 ()
Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2019-08-30
Couceiro, J., Lindgren, O., Hansson, L., Söderström, O. & Sandberg, D. (2019). Real-time wood moisture-content determination using dual-energy X-ray computed tomography scanning. Wood Material Science & Engineering, 14(6), 437-444
Open this publication in new window or tab >>Real-time wood moisture-content determination using dual-energy X-ray computed tomography scanning
Show others...
2019 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 14, no 6, p. 437-444Article in journal (Refereed) Epub ahead of print
Abstract [en]

The estimation of the pixel-wise distribution of the moisture content (MC) in wood using X-ray computed tomography (CT) requires two scans of the same wood specimen at different MCs, one of which is known. Image-processing algorithms are needed to compensate for the anisotropic distortion that wood undergoes as it dries. An alternative technique based on dual-energy CT (DECT) to determine MC in wood has been suggested by several authors. The purpose of the present study was to evaluate the hypothesis that DECT can be used for the determination of MC in real time. A method based on the use of the quotient between the linear attenuation coefficients (μ) at different acceleration voltages (the so-called quotient method) was used. A statistical model was created to estimate the MC in solid sapwood of Scots pine, Norway spruce and brittle willow. The results show a regression model with R2 > 0.97 that can predict the MC in these species with a RMSE of prediction of 0.07, 0.04 and 0.11 (MC in decimal format) respectively and at MC levels ranging from the green to the totally dry condition. Individual measurements of MC show an uncertainty of up to ±0.4. It is concluded that under the conditions prevailing in this study, and in studies referred to in this paper, it is not possible to measure MC with DECT.

Place, publisher, year, edition, pages
London: Taylor & Francis, 2019
Keywords
CT-scanning, dual-energy X-ray absorptiometry, wood drying, attenuation coefficient
National Category
Wood Science Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-76369 (URN)10.1080/17480272.2019.1650828 (DOI)
Available from: 2019-10-12 Created: 2019-10-12 Last updated: 2019-10-12
Couceiro, J. (2019). X-ray computed tomography to study moisture distribution in wood. (Doctoral dissertation). Luleå tekniska universitet
Open this publication in new window or tab >>X-ray computed tomography to study moisture distribution in wood
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

X-ray computed tomography (CT) has been used as an analysing tool for different features in wood research since the beginning of the1980s, but it can also be used to study wood-water interactions in different ways, such as by determining wood moisture content (MC). The determination of wood MC with CT requires two CT images: one at the unknown moisture distribution and a second one at a known reference MC level, usually at oven-dry condition. The two scans are then compared, and the MC is calculated based on the differences between the images. If the goal is to determine the MC in local regions within the wood volume, e.g. when studying moisture gradients in wood drying, wood shrinkage must be taken into account during the data processing of the images. The anisotropy of wood shrinkage creates an obstacle, however, since the shrinkage is not uniform throughout the wood specimen. The technique is thus limited in two ways: it cannot measure MC in local regions and it cannot do it in real time.

The objective of this thesis was to study methods to overcome these two limitations. The work explores up to three different methods to estimate local MC from CT images in real time. The first method determines shrinkage for each pixel using digital image correlation (DIC) and is embedded in a broader method to estimate the MC, which verified against a reference. It involves several steps in different pieces of software, making it time-consuming and creating many sources of possible experimental errors. The determination of shrinkage within this method is further explored to enable the implementation of all steps in a unique piece of software. It is shown that it is possible to calculate MC through this method with a root mean square error of prediction of 1.4 percentage points for MC between 6 and 25%.

The second method studied succeeds in determining the MC distribution in research applied to wood drying, but the calculation of shrinkage differs from the previous method: instead of calculating shrinkage in the radial and tangential directions, it does so by using the displacement information generated from the spatial alignment of the CT images. Results show that the algorithm can provide consistent data of internal MC distribution of wood at the pixel level that entail continuing researching wood drying processes with an improvement in the accuracy of the MC determination. It represents an improvement regarding the first method because the calculation is fast and highly automatized in a single piece of software.

The third method studied is the application of dual energy CT (DECT) to moisture. DECT would provide means for MC calculation at the pixel level and, potentially, in real time, which would mean an important breakthrough in wood drying research. Previous research shows promising results, but its implementation in medical CT, the tool used throughout this work, has shown poor predicting ability. Nevertheless, further research is encouraged.

The work done in this thesis proves that it is possible to measure local distribution of MC in wood using CT with accuracy and precision. It also shows that further research could potentially provide a means for MC estimation in real time.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2019
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Wood Science
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-73860 (URN)978-91-7790-382-6 (ISBN)978-91-7790-383-3 (ISBN)
Public defence
2019-09-12, Hörsal A (A193), Skellefteå, 09:00 (English)
Opponent
Supervisors
Available from: 2019-05-07 Created: 2019-05-07 Last updated: 2019-08-21Bibliographically approved
Couceiro, J., Hansson, L., Ahec, A. & Sandberg, D. (2018). CT-scanning of the drying process of Eucalyptus nitens.. In: Cárcel JA, Polo GC, García-Pérez JV, Mulet A, Rosselló C., (Ed.), Proceedings of 21st International Drying Symposium.: . Paper presented at 21st International Drying Symposium, Valencia, Spain, Sep 11-14, 2018 (pp. 1269-1276). Valencia: Editorial Universitat Politècnica de València
Open this publication in new window or tab >>CT-scanning of the drying process of Eucalyptus nitens.
2018 (English)In: Proceedings of 21st International Drying Symposium. / [ed] Cárcel JA, Polo GC, García-Pérez JV, Mulet A, Rosselló C.,, Valencia: Editorial Universitat Politècnica de València , 2018, p. 1269-1276Conference paper, Published paper (Refereed)
Abstract [en]

The drying of Eucalyptus nitens is a troublesome process as the species is extremely prone to drying defects. This paper reports ongoing research toimprove the understanding of surface checking and cell collapse in Chilean grown Eucalyptus nitens during drying. Computed tomography (CT) scanning was used as a powerful tool for studying the internal changes in the wood-material during the drying process. Different levels of temperatures have been tested with the same equilibrium moisture content (EMC) conditions and low air velocity. The results confirm that a low drying temperature and a low air velocity, which results in a slow rate of drying, reduce internal cell collapse and surface checking .

Place, publisher, year, edition, pages
Valencia: Editorial Universitat Politècnica de València, 2018
Keywords
Cell collapse, computed tomography, surface checks, wood drying, internal checks
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-71201 (URN)10.4995/ids2018.2018.7380 (DOI)000477977800160 ()978-84-9048-688-7 (ISBN)
Conference
21st International Drying Symposium, Valencia, Spain, Sep 11-14, 2018
Available from: 2018-10-13 Created: 2018-10-13 Last updated: 2019-09-13Bibliographically approved
Hansson, L., Couceiro, J. & Fjellner, B.-A. (2017). Estimation of shrinkage coefficients in radial and tangential directions from CT images. Wood Material Science & Engineering, 12(4), 251-256
Open this publication in new window or tab >>Estimation of shrinkage coefficients in radial and tangential directions from CT images
2017 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, no 4, p. 251-256Article in journal (Refereed) Published
Abstract [en]

The aim of the present work was to use the displacement information generated from the spatial alignment in order to compute wood shrinkage in the radial and tangential directions in computed tomography (CT) images, and to compare the results with those obtained with computer-aided design software on the same images. To estimate the shrinkage coefficients from tomography images, wood specimens in the green state, equilibrium moisture content 15% and 8% state and oven dry condition were scanned. Specimens were taken from Norway spruce and Scots pine logs. The root-mean-square-error calculations showed acceptable small differences between the two measuring methods, which means that the algorithm is a useful tool for estimating the shrinkage coefficients in radial and tangential direction from CT images. This provides an image processing tool to monitor the dimensional changes during the drying and heat treatment process. 

Place, publisher, year, edition, pages
Taylor & Francis, 2017
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-60142 (URN)10.1080/17480272.2016.1249405 (DOI)000402709800009 ()2-s2.0-84997272329 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-06-07(andbra)

Available from: 2016-11-03 Created: 2016-11-03 Last updated: 2019-05-07Bibliographically approved
Couceiro, J. & Lindgren, O. (2016). Estimation of miosture content in wood using dual x-ray energies in a medical CT-scanner. In: Process Technologies for the Forest & Biobased Products Industries: PTF BPI 2016. Paper presented at 4th International Conference on Process Technologies for the Forest and Biobased Products Industries, PTF BPI 2016, St. Simons, Georgia, USA, October 25-26 2016 (pp. 22).
Open this publication in new window or tab >>Estimation of miosture content in wood using dual x-ray energies in a medical CT-scanner
2016 (English)In: Process Technologies for the Forest & Biobased Products Industries: PTF BPI 2016, 2016, p. 22-Conference paper, Oral presentation with published abstract (Other academic)
National Category
Wood Science Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-61069 (URN)
Conference
4th International Conference on Process Technologies for the Forest and Biobased Products Industries, PTF BPI 2016, St. Simons, Georgia, USA, October 25-26 2016
Available from: 2016-12-13 Created: 2016-12-13 Last updated: 2017-11-24Bibliographically approved
Couceiro, J., Hansson, L. & Sandberg, D. (2016). In situ CT-scanning for detection of internal checking and cell collapse during drying of hardwood species. In: Teischinger A., Németh R., Rademacher P., Bak M. & Fodor F. (Eds.) (Ed.), The 7th European Conference on Hardwood, Eco-efficient resource wood with special focus on hardwoods: . Paper presented at 7th European Conference on Hardwood, Eco-efficient resource wood with special focus on hardwoods, Sopron, 8–9th September 2016 (pp. 58-59). Sopron: University of West Hungary
Open this publication in new window or tab >>In situ CT-scanning for detection of internal checking and cell collapse during drying of hardwood species
2016 (English)In: The 7th European Conference on Hardwood, Eco-efficient resource wood with special focus on hardwoods / [ed] Teischinger A., Németh R., Rademacher P., Bak M. & Fodor F. (Eds.), Sopron: University of West Hungary , 2016, p. 58-59Conference paper, Published paper (Refereed)
Abstract [en]

During the drying of sawn timber, hydrostatic tension forces within the cell may exceed the compressive strength perpendicular to the grain of the thin cell wall and the cell then collapses. This phenomenon is common in hardwoods such as Sequoia sempervirens, Thuja plicata, Tsuga heterophylla, Juglans nigraand many species of eucalyptus and oak. Usually, this leads to severe surface deformation, and both surface and internal checking(honeycombing) may occur. The quality of the final product is lowered by these cracks and deformations. The aim of this study was to investigate, by CT-scanning samples throughout the drying process, whether it is possible to detect when and how cracking and deformation occurs and develops in specimens of Eucalyptus nitens. Based on this knowledge, better drying schedules can be developed to improve the yield and ensure a higher quality of the sawn timber. Three specimens, one specimen in each drying run, of Eucalyptus nitens were used for the tests. Their cross-sectional dimensions, prior to drying, were 105x23 mm2 and their length was 70 cm. A specially designed laboratory drying kiln that fits within the gantry of a Siemens Somatom Emotion medical CT-scanner was used (Fig. 1). With this equipment, it is possible to scan the inside of the kiln without interrupting the drying process.

Place, publisher, year, edition, pages
Sopron: University of West Hungary, 2016
Keywords
CT-scanning, Eucalyptus nitens, wood drying, image processing, cell collapse
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-60264 (URN)978-963-334-291-6 (ISBN)
Conference
7th European Conference on Hardwood, Eco-efficient resource wood with special focus on hardwoods, Sopron, 8–9th September 2016
Available from: 2016-11-10 Created: 2016-11-10 Last updated: 2017-11-24Bibliographically approved
Couceiro, J., Vikberg, T., Hansson, L. & Morén, T. (2016). In Situ CT-Scanning of Checking and Collapse Behaviour of Eucalyptus nitens During Drying. In: Proceedings of the 59th International Convention of Society of Wood Science and Technology March 6-10, 2016 – Curitiba, Brazil: . Paper presented at 59th International Convention of Society of Wood Science and Technology, Curitiba, Brazil, March 6-10, 2016.
Open this publication in new window or tab >>In Situ CT-Scanning of Checking and Collapse Behaviour of Eucalyptus nitens During Drying
2016 (English)In: Proceedings of the 59th International Convention of Society of Wood Science and Technology March 6-10, 2016 – Curitiba, Brazil, 2016Conference paper, Published paper (Other academic)
Abstract [en]

Eucalyptus nitens has become a commercially important species in Chile and it isrepresenting one of the fastest growing wood-stock in the country. Today, it is widelyused for pulp and paper production, but the interest in using the solid wood has increasedin recent years. Before the sawn timber can be utilized, its moisture content must bereduced. Often during drying, hydrostatic tension forces within the cell exceed thecompressive strength of the thin cell wall of Eucalyptus nitens and the cell collapses. Thisphenomenon usually leads to severe surface deformation and both surface and internalcracks (honeycombing). Yield and quality of the final product, and thereby sawmills’profitability, are decreased by these cracks and deformations. The aim of this study wasto investigate, by CT-scanning samples throughout the drying process, if it is possible todetect when and how cracking and deformation occurs and develops in specimens ofEucalyptus nitens from Chile. Based on this knowledge, better drying schedules canhopefully be developed to improve the yield and provide a higher end-quality of the sawntimber.

Keywords
CT-scanning, Eucalyptus nitens, wood drying, image processing, cell collapse
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-61768 (URN)
Conference
59th International Convention of Society of Wood Science and Technology, Curitiba, Brazil, March 6-10, 2016
Available from: 2017-02-02 Created: 2017-02-01 Last updated: 2018-05-22Bibliographically approved
Couceiro, J., Neyses, B. & Sandberg, D. (2016). In-situ moisture content and density measurements in surface densified wood using dual X-ray absorptiometry in medical CT-scanning. In: BIOCOMP 2016: The 13th Pacific Rim Bio-Based Composites Symposium, Bio-based composites for a sustainable future.. Paper presented at 13th Pacific Rim Bio-Based Composites Symposium, Conceptión, Chile, 13-15 November 2016 (pp. 92). Concepción: University of Concepción, 2, Article ID NA01.
Open this publication in new window or tab >>In-situ moisture content and density measurements in surface densified wood using dual X-ray absorptiometry in medical CT-scanning
2016 (English)In: BIOCOMP 2016: The 13th Pacific Rim Bio-Based Composites Symposium, Bio-based composites for a sustainable future., Concepción: University of Concepción , 2016, Vol. 2, p. 92-, article id NA01Conference paper, Poster (with or without abstract) (Refereed)
Place, publisher, year, edition, pages
Concepción: University of Concepción, 2016
National Category
Wood Science Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-60703 (URN)
Conference
13th Pacific Rim Bio-Based Composites Symposium, Conceptión, Chile, 13-15 November 2016
Available from: 2016-11-27 Created: 2016-11-27 Last updated: 2017-11-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7270-1920

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