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Skog, Johan
Publications (10 of 16) Show all publications
Olofsson, L., Broman, O., Skog, J., Fredriksson, M. & Sandberg, D. (2019). Multivariate product adapted grading of Scots pine sawn timber for an industrial customer, part 1: Method development. Wood Material Science & Engineering, 14(6), 428-436
Open this publication in new window or tab >>Multivariate product adapted grading of Scots pine sawn timber for an industrial customer, part 1: Method development
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2019 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 14, no 6, p. 428-436Article in journal (Refereed) Published
Abstract [en]

Rule-based automatic grading (RBAG) of sawn timber is a common type of sorting system used in sawmills, which is intricate to customise for specific customers. This study further develops an automatic grading method to grade sawn timber according to a customer’s resulting product quality. A sawmill’s automatic sorting system used cameras to scan the 308 planks included in the study. Each plank was split at a planing mill into three boards, each planed, milled, and manually graded as desirable or not. The plank grade was correlated by multivariate partial least squares regression to aggregated variables, created from the sorting system’s measurements at the sawmill. Grading models were trained and tested independently using 5-fold cross-validation to evaluate the grading accuracy of the holistic-subjective automatic grading (HSAG), and compared with a resubstitution test. Results showed that using the HSAG method at the sawmill graded on average 74% of planks correctly, while 83% of desirable planks were correctly identified. Results implied that a sawmill sorting station could grade planks according to a customer’s product quality grade with similar accuracy to HSAG conforming with manual grading of standardised sorting classes, even when the customer is processing the planks further.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Sawn timber, visual grading, customer adoption, discriminant analysis
National Category
Wood Science Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-73967 (URN)10.1080/17480272.2019.1617779 (DOI)
Funder
Vinnova, 2018-02749
Note

Validerad;2019;Nivå 2;2019-10-10 (johcin)

Available from: 2019-05-16 Created: 2019-05-16 Last updated: 2019-10-16Bibliographically approved
Olofsson, L., Broman, O., Skog, J., Fredriksson, M. & Sandberg, D. (2019). Multivariate Product Adapted Grading of Scots Pine Sawn Timber for an Industrial Customer, Part 2: Robustness to Disturbances. Wood Material Science & Engineering, 14(6), 420-427
Open this publication in new window or tab >>Multivariate Product Adapted Grading of Scots Pine Sawn Timber for an Industrial Customer, Part 2: Robustness to Disturbances
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2019 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 14, no 6, p. 420-427Article in journal (Refereed) Published
Abstract [en]

Holistic-subjective automatic grading (HSAG) of sawn timber by an industrial customer's product outcome is possible through the use of multivariate partial least squares discriminant analysis (PLS-DA), shown by part one of this two-part study. This second part of the study aimed at testing the robustness to disturbances of such an HSAG system when grading Scots Pine sawn timber partially covered in dust. The set of 308 clean planks from part one of this study, and a set of 310 dusty planks, that by being stored inside a sawmill accumulated a layer of dust, were used. Cameras scanned each plank in a sawmill's automatic sorting system that detected selected feature variables. The planks were then split and processed at a planing mill, and the product grade was correlated to the measured feature variables by partial least squares regression. Prediction models were tested using 5-fold cross-validation in four tests and compared to the reference result of part one of this study. The tests showed that the product adapted HSAG could grade dusty planks with similar or lower grading accuracy compared to grading clean planks. In tests grading dusty planks, the disturbing effect of the dust was difficult to capture through training.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Sawn timber, visual grading, customer adoption, discriminant analysis
National Category
Wood Science Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-73854 (URN)10.1080/17480272.2019.1612944 (DOI)000469741800001 ()2-s2.0-85065546163 (Scopus ID)
Funder
Vinnova, 2018-02749
Note

Validerad;2019;Nivå 2;2019-10-16 (johcin)

Available from: 2019-05-06 Created: 2019-05-06 Last updated: 2019-10-16Bibliographically approved
Johansson, E., Berglund, A. & Skog, J. (2016). Comparing predictability of board strength between computed tomography, discrete x-ray, and 3D scanning of Norway spruce logs (ed.). Wood Material Science & Engineering, 11(2), 116-125
Open this publication in new window or tab >>Comparing predictability of board strength between computed tomography, discrete x-ray, and 3D scanning of Norway spruce logs
2016 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 11, no 2, p. 116-125Article in journal (Refereed) Published
Abstract [en]

Strength graded boards of Norway spruce (Picea abies (L.) Karst.) are important products for many Scandinavian sawmills. If the bending strength of the produced boards can be predicted before sawing the logs, the raw material can be used more efficiently. In previous studies it is shown that the bending strength can be predicted to some extent using discrete X-ray scanning of logs. In this study, we have evaluated if it is possible to predict bending strength of Norway spruce boards with higher accuracy using computed tomography (CT) scanning of logs compared to a combination of discrete X-ray and 3D scanning. The method was to construct multivariate models of bending strength for three different board dimensions. Our results showed that CT scanning of logs produces better models of bending strength compared to a combination of discrete X-ray and 3D scanning. The main reason for this difference was the benefit of knowing the position of where the boards were cut from the logs and therefore detailed knot information could be used in the prediction models. Due to the small number of observations in this study, care should be taken when comparing the resulting prediction models to results from other studies

National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-11954 (URN)10.1080/17480272.2015.1022875 (DOI)000370663900005 ()2-s2.0-84925425630 (Scopus ID)b00e80f2-0258-4caf-81d1-58b938afafb0 (Local ID)b00e80f2-0258-4caf-81d1-58b938afafb0 (Archive number)b00e80f2-0258-4caf-81d1-58b938afafb0 (OAI)
Note

Validerad; 2016; Nivå 2; 20140926 (erikjo)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Berglund, A., Johansson, E. & Skog, J. (2014). Value optimized log rotation for strength graded boards using computed tomography (ed.). Paper presented at . European Journal of Wood and Wood Products, 72(5), 635-642
Open this publication in new window or tab >>Value optimized log rotation for strength graded boards using computed tomography
2014 (English)In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 72, no 5, p. 635-642Article in journal (Refereed) Published
Abstract [en]

A possible application for an industrial computed tomography scanner in a sawmill is finding an optimal rotational position of logs with respect to knots and outer shape. Since a computed tomography scanner is a great investment, it is important to investigate potential profitability of such an investment for different production strategies. The objective of this study was to investigate the potential value increase of the sawn timber of Norway spruce (Picea abies (L.) Karst.) by rotating logs to their optimum position prior to sawing compared with sawing all logs in horns down position. The production strategy evaluated by log breakdown simulation in this case study was to produce strength graded timber of the center boards, while the side boards were appearance graded. This case study showed an average value increase with respect to the value of center boards, side boards and chips of 11 %.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-2494 (URN)10.1007/s00107-014-0822-8 (DOI)000340497800009 ()2-s2.0-84906502712 (Scopus ID)01cce25a-4f3c-49c1-b299-c2cb110e4514 (Local ID)01cce25a-4f3c-49c1-b299-c2cb110e4514 (Archive number)01cce25a-4f3c-49c1-b299-c2cb110e4514 (OAI)
Note
Validerad; 2014; 20130730 (bendar)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Johansson, E., Johansson, D., Skog, J. & Fredriksson, M. (2013). Automated knot detection for high speed computed tomography on Pinus sylvestris L. and Picea abies (L.) Karst. using ellipse fitting in concentric surfaces (ed.). Paper presented at . Computers and Electronics in Agriculture, 96, 238-245
Open this publication in new window or tab >>Automated knot detection for high speed computed tomography on Pinus sylvestris L. and Picea abies (L.) Karst. using ellipse fitting in concentric surfaces
2013 (English)In: Computers and Electronics in Agriculture, ISSN 0168-1699, E-ISSN 1872-7107, Vol. 96, p. 238-245Article in journal (Refereed) Published
Abstract [en]

High speed industrial computed tomography (CT) scanning of sawlogs is new to the sawmill industry and therefore there are no properly evaluated algorithms for detecting knots in such images. This article presents an algorithm that detects knots in CT images of logs by segmenting the knots with variable thresholds on cylindrical shells of the CT images. The knots are fitted to ellipses and matched between several cylindrical shells. Parameterized knots are constructed using regression models from the matched knot ellipses. The algorithm was tested on a variety of Scandinavian Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) with a knot detection rate of 88–94% and generating about 1% falsely detected knots.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-8418 (URN)10.1016/j.compag.2013.06.003 (DOI)000323795700022 ()2-s2.0-84880384633 (Scopus ID)6ee1639c-6afa-4b91-8c86-8608b761e1eb (Local ID)6ee1639c-6afa-4b91-8c86-8608b761e1eb (Archive number)6ee1639c-6afa-4b91-8c86-8608b761e1eb (OAI)
Note
Validerad; 2013; 20130702 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Skog, J. (2013). Characterization of sawlogs using industrial X-ray and 3D scanning (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Characterization of sawlogs using industrial X-ray and 3D scanning
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the Nordic countries, sawlogs are typically sorted upon arrival at the sawmill based on species and dimension. By processing batches of logs with similar size, the sawing process becomes more efficient; the need to change sawing pattern between individual logs is reduced, and the handling of sawn goods is simplified, since the number of different dimensions produced simultaneously decreases. However, since wood is a biological material with great heterogeneity, there will be a large variation in the properties also of boards sawn from logs of similar size. This means that a significant amount of the boards may be carrying unwanted combinations of dimension and grade, so called off-grade products. The problem with off-grade products may be addressed before sawing by the selection of suitable sawing patterns for each log, i.e., using the right logs for the right products. This requires knowledge of the internal quality of the log before sawing. Some information can be obtained from the outer shape measured by an optical three-dimensional (3D) scanner and more detailed information can be obtained using an X-ray log scanner. Today, the use of X-ray log scanners is becoming increasingly common, and most sawmills installing an X-ray scanner already have a 3D scanner present. This raises the question of possible benefits from combining the X-ray and 3D scanning techniques. In this thesis, a method is presented whereby the outer shape of the log measured by a 3D scanner is utilized to estimate the X-ray path lengths through the wood. This converts the X-ray images into green density images of the log, which may in turn be used to calculate quality variables such as heartwood diameter, dry density, moisture content and presence of top rupture. The methods have been tested on Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) sawlogs using X-ray scanners with one or two measurement directions. The developed methods show a great improvement in precision compared to calculations based on uncompensated X-ray images, and most of the algorithms presented in the thesis have now been implemented in industrial scanner software and are ready for use at the sawmills. This will give the sawmill industry new possibilities to control the production of special products where heartwood diameter and density are important and will lead to less waste and improved profitability for the sawmills.The thesis also describes a method where X-ray scanning is utilized to automatically perform parts of the log grading for payment. This method can improve productivity in the sawmills by remedying a severe bottleneck in the production chain. An authorization of this method for semiautomatic log grading for payment is expected to further increase the industry’s interest in X-ray scanning.

Abstract [sv]

I Norden sorteras sågtimmer vanligtvis vid ankomst till sågverket, baserat på träslag och dimension. Genom att i följd såga ett stort antal stockar av liknande storlek kan sågningen effektiviseras eftersom behovet att byta postning mellan varje stock minskar och färre dimensioner av sågad vara behöver hanteras samtidigt. Eftersom trä är ett biologiskt material med stor olikformighet kommer dock även bräder sågade från stockar av liknande storlek att uppvisa stor spridning i egenskaper. Detta innebär att en stor andel av de bräder som sågas kommer bära oönskade kombinationer av dimension och kvalitet. Problemet kan åtgärdas före sågning genom att välja rätt sågmönster för varje stock, det vill säga genom att styra varje stock mot den bäst lämpade slutprodukten. Detta kräver kännedom om stockens inre egenskaper före sågning. Viss sådan kvalitetsinformation kan erhållas från den yttre formen, mätt med en optisk 3D-mätram och mer detaljerad information kan fås med hjälp av en röntgenmätram.Idag har användandet av röntgenmätramar blivit allt vanligare, och de flesta sågverk som väljer att investera i ett röntgensystem har redan en 3D-mätram i sin timmersortering. Detta väcker frågan om vilka fördelar som kan nås genom att kombinera röntgen- och 3D-mätteknikerna. I den här avhandlingen presenteras en metod där stockens yttre form används för att uppskatta röntgenstrålningens gångväg genom stocken. Genom att kompensera för gångvägen är det möjligt att beräkna en rådensitetsbild för stocken, vilken i sin tur kan användas för att beräkna viktiga kvalitetsvariabler såsom kärnvedsdiameter, torrdensitet, fuktkvot och förekomst av toppbrott. Metoden har testats på sågtimmer av tall (Pinus sylvestris L.) och gran (Picea abies (L.) Karst.) och röntgenmätramar med en och två mätriktningar har använts.De nyutvecklade beräkningsmetoderna uppvisar mycket högre precision än beräkningar baserade på okompenserade röntgenbilder. Flertalet av de algoritmer som presenteras i avhandlingen har nu implementerats i industriell röntgenprogramvara och är redo för användning på sågverken. Detta kommer att ge sågverksindustrin nya möjligheter att styra tillverkningen av specialprodukter med krav på exempelvis kärnvedsdiameter och densitet och kommer att leda till mindre spill och förbättrad lönsamhet för sågverken.Avhandlingen beskriver också en metod där röntgenskanning nyttjas för att automatisera delar av den prisgrundande vederlagsmätningen av sågtimmer. Eftersom vederlags-mätningen är en flaskhals vid många sågverk kan detta att leda till en kraftig förbättring av produktiviteten. Ett metodgodkännande för semiautomatisk vederlagsmätning förväntas därför ytterligare höja industrins intresse för röntgenmätteknik.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2013. p. 54
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-26152 (URN)ce4a6ede-cb42-4cab-903a-21fe84341cc3 (Local ID)978-91-7439-616-4 (ISBN)978-91-7439-617-1 (ISBN)ce4a6ede-cb42-4cab-903a-21fe84341cc3 (Archive number)ce4a6ede-cb42-4cab-903a-21fe84341cc3 (OAI)
Note
Godkänd; 2013; 20130409 (johsko); Tillkännagivande disputation 2013-05-08 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Johan Skog Ämne: Träteknik/Wood Technology Avhandling: Characterization of Sawlogs Using Industrial X-ray and 3D Scanning Opponent: Professor Olav Höjbö, Institutt för Naturförvaltning, Universitetet för Miljö- och Biovetenskap, Ås, Norge, Ordförande: Professor Anders Grönlund, Avd för träteknologi, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Fredag den 31 maj 2013, kl 10.00 Plats: Hörsal A, campus Skellefteå, Luleå tekniska universitetAvailable from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-24Bibliographically approved
Fredriksson, M. & Skog, J. (2012). Reconstruction of knots from simulated discrete x-ray images of Pinus Sylvestris logs (ed.). Paper presented at IUFRO Conference : Division 5 Forest Products 08/07/2012 - 13/07/2012. Paper presented at IUFRO Conference : Division 5 Forest Products 08/07/2012 - 13/07/2012.
Open this publication in new window or tab >>Reconstruction of knots from simulated discrete x-ray images of Pinus Sylvestris logs
2012 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

For many years it has been of interest to be able to predict the properties of sawn wood products from tree features. X-ray technology has made it possible to measure internal as well as external features of saw logs, and to use these features for predicting log quality. However, data available for simulation of the sawing process and prediction of sawn timber quality has, until now, been limited to logs scanned using computed tomography.The objective of this study is to develop a method for reconstruction of parametrically described whorls and knots from industrial scanning of Scots pine (Pinus sylvestris L.) logs, using discrete Xray images. The method is designed using the logs in the Swedish pine stem bank (SPSB) as data basis, and is based on a few predictor features extracted from these logs, namely whorl volume, distance between whorls, and distance between pith and surface. These features are measured in simulated discrete X-ray images of the logs in the SPSB, and virtual models of the whorls and knots are created, using a feature- and knowledge based model. Virtual logs are then composed using the reconstructed knots within the original shape of the logs. Simulated test sawing of the virtual logs shows that the reconstruction method results in a representative model of the knot structure in the log, when considering the grade distribution of the sawn timber produced by the simulation program. The results of this study can for instance be used for improved online quality predictions at sawmills. One step in this direction is to use industrial X-ray data to enlarge the amount of log data available for sawing simulation research. Future work should focus on developing practical applications of the results presented here.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-40236 (URN)f49155f4-9ca7-4de6-99af-a02b085d941e (Local ID)f49155f4-9ca7-4de6-99af-a02b085d941e (Archive number)f49155f4-9ca7-4de6-99af-a02b085d941e (OAI)
Conference
IUFRO Conference : Division 5 Forest Products 08/07/2012 - 13/07/2012
Note
Godkänd; 2012; 20120925 (magfre)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Grönlund, A. & Skog, J. (2012). Use of x-ray for detection of internal log features (ed.). Paper presented at IUFRO Conference : Division 5 Forest Products 08/07/2012 - 13/07/2012. Paper presented at IUFRO Conference : Division 5 Forest Products 08/07/2012 - 13/07/2012.
Open this publication in new window or tab >>Use of x-ray for detection of internal log features
2012 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

To have knowledge about internal features in saw logs have always been a very important wish among people working in the sawmill industry. The reason for that wish is that with this knowledge it is possible to disintegrate logs in an optimal way.X-ray linear attenuation depends mainly on density and size of the object that is hit by the X-ray beam. This makes X-ray technology suitable for detection of different features in saw logs as there is a density difference between clear wood and many important internal features such as different kind of knots.Medical computer tomography (CT) utilise X-ray to detect internal features in human bodies but is also a very good tool for detection of features in saw logs. However, medical CT-scanners are only used for research purposes in the wood sector as they are far to slow for use in the industry.In order to be able to detect internal log features in industrial speed Log-Scanners with one to four fixed X-ray sources have been developed. With these scanners, that now are used at many sawmills, it is possible to detect and measure features such as: diameter under bark, log type, species, knot parameters, annual ring width, density, heartwood, strength etc. These scanners with fixed sources have a much lower information density than medical CT-scanners but are much faster. The time for scanning a log has been reduced from about two hours to 1.5 seconds. The big draw-back with the scanners with fixed sources is that they give very little information about how defects are located in the rotational direction. However, in order to overcome this drawback, an industrial CT-scanner is now under development. This scanner will operate in industrial speed and will at the same time have an information density that is comparable with a medical CT-scanner.The aim of this presentation is to summarize the current knowledge on X-ray scanning of wood and to propose some suitable applications and strategies for using a fast CT scanner in the wood industry.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-40126 (URN)f1f386a9-0d4e-4ddd-a016-8bd2725c558f (Local ID)f1f386a9-0d4e-4ddd-a016-8bd2725c558f (Archive number)f1f386a9-0d4e-4ddd-a016-8bd2725c558f (OAI)
Conference
IUFRO Conference : Division 5 Forest Products 08/07/2012 - 13/07/2012
Note
Godkänd; 2012; 20120926 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Skog, J. & Oja, J. (2010). Density measurements in Pinus sylvestris sawlogs combining X-rayand three-dimensional scanning (ed.). Paper presented at . Scandinavian Journal of Forest Research, 25(5), 470-481
Open this publication in new window or tab >>Density measurements in Pinus sylvestris sawlogs combining X-rayand three-dimensional scanning
2010 (English)In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 25, no 5, p. 470-481Article in journal (Refereed) Published
Abstract [en]

Wood density is an important quality variable, closely related to the mechanical properties of the wood. Precise wood density measurements in the log sorting would enable density sorting of logs for products such as strength-graded wood and fingerjointed wood. Density sorting of logs would also give more homogeneous drying properties and thus improve the quality of the final products. By compensating the radiographs from an X-ray log scanner for the varying path lengths using outer shape data from a three-dimensional (3D) scanner, it is possible to make precise estimates of both green and dry density. Measurements on simulated industrial data were compared with densities measured in computed tomographic (CT) images for 560 Scots pine (Pinus sylvestris L.) logs. It was found that green sapwood density could be measured with predictability R2 = 0.65 and root mean square error (RMSE) of 25 kg m-3. Green and dry heartwood densities were measured with similar precision: R2 = 0.79 and RMSE = 32 kg m-3 for green density and R2 = 0.83 and RMSE = 32 kg m-3 for dry density.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-13057 (URN)10.1080/02827581.2010.509326 (DOI)000282594700009 ()2-s2.0-77955258875 (Scopus ID)c3738820-dcee-11df-8b36-000ea68e967b (Local ID)c3738820-dcee-11df-8b36-000ea68e967b (Archive number)c3738820-dcee-11df-8b36-000ea68e967b (OAI)
Note
Validerad; 2010; 20101021 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Skog, J., Vikberg, T. & Oja, J. (2010). Sapwood moisture content measurements in Scots Pine sawlogs combining X-ray and 3D scanning (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. 357-362). Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Sapwood moisture content measurements in Scots Pine sawlogs combining X-ray and 3D scanning
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. 357-362Conference paper, Published paper (Refereed)
Abstract [en]

Wood industry of today deals with large volumes in an almost automatic process, which is not fully adapted tothe variability of the raw material. Consequently, it is crucial to sort the wood according to material properties inorder to process the wood efficiently and to obtain high quality end products. One material property which could beused for sorting is the moisture content of the sapwood, an important parameter for both the processing and the endproducts.Most large Swedish sawmills are using 3D scanners for quality sorting of Scots pine (Pinus sylvestris L.)sawlogs based on outer shape. Recently, some sawmills have also invested in X-ray log scanners in order to sort thesawlogs based on inner properties. It has previously been shown that, by combining raw data from industrial 3D andX-ray log scanners using path length compensation, green sapwood density and dry heartwood density can beestimated.In this study, the dry heartwood density was used to find an estimate of the dry sapwood density, thus allowingthe calculation of the sapwood moisture content. The log scanner data used in this study was simulated from 560Scots pine sawlogs which had previously been scanned in a computed tomography (CT) scanner. The estimatedsapwood moisture contents were then compared to reference values calculated by drying samples to 9% moisturecontent.It was found that the moisture content estimate could be used to separate the logs into two groups with high andlow moisture content, correctly identifying all logs with very low moisture content as dry logs. Out of all logs, 70%were correctly classified. The moisture content estimate could also be compared to the dry density dependentmaximum moisture content and used to identify logs that have actually started to dry.

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-28117 (URN)1cd480d0-25f8-11df-be83-000ea68e967b (Local ID)1cd480d0-25f8-11df-be83-000ea68e967b (Archive number)1cd480d0-25f8-11df-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
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