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  • 1.
    Berglund, Anders
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Broman, Olof
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Oja, Johan
    Grönlund, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Customer adapted grading of Scots pine sawn timber using a multivariate method2015Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 30, nr 1, s. 87-97Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To define new grading rules, or to customize the ones in use in a rule-based automatic grading system of boards, is a time-consuming job for a sawmill engineer. This has the effect that changes are rarely made. The objective of this study was to continue the development of a method that replaces the calibration of grading rule settings by a holistic-subjective automatic grading, using multivariate models. The objective was also to investigate if this approach can improve sawmill profitability and at the same time have a satisfied customer. For the study, 323 Scots pine (Pinus sylvestris L.) boards were manually graded according to preferences of an important customer. That is, a customer that regularly purchases significant volumes of sawn timber. This manual grading was seen as reference grading in this work. The same boards were also scanned and graded by a rule-based automatic grading system, calibrated for the same customer. Multivariate models for prediction of board grade based on aggregated knot variables, obtained from the scanning, were calibrated using partial least squares regression. The results show that prediction of board grades by the multivariate models were more correct, with respect to the manual grading, than the grading by the rule-based automatic grading system. The prediction of board grades based on multivariate models resulted in 76-87% of the boards graded correctly, according to the manual grading, while the corresponding number was 63% for the rule-based automatic grading system.

  • 2.
    Brege, Staffan
    et al.
    Industrial Marketing, Management and Engineering, Linkping University.
    Nord, Tomas
    Industrial Marketing, Management and Engineering, Linkping University.
    Sjöström, Roland
    Industrial Marketing, Management and Engineering, Linkping University.
    Stehn, Lars
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Value-added strategies and forward integration in the Swedish sawmill industry: positioning and profitability in the high-volume segment2010Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 25, nr 5, s. 482-493Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The changing market conditions for the Swedish sawmill industry place a focus on a better understanding of the pros and cons of value-added and forward integration strategies. The purpose of this article is to describe and explain recent value-added strategies in the Swedish sawmill industry. The study includes strategies from 13 of the 15 largest sawmill companies for the period between 2002 and 2005, describing a differentiation between value added in primary sawmill production and forward integration into secondary production. It also aims to relate some basic conditions, such as company size, company growth and corporate strategy, to value added and forward integration to profitability. The results show strong positive and significant correlations between forward integration, value added in primary production (somewhat weaker) and unit revenue, and profitability measured as return on investment. There were no strong or significant correlations between size and profitability, playing down the importance of economies of scale (among these already large companies). An interesting result is the much higher profitability of the buying sawmill companies compared with the forest corporations, stressing the importance of both a long-term strategy when investing in value-added activities and ultimately the priorities of ownership.

  • 3. Brännström, Mattias
    et al.
    Oja, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Grönlund, Anders
    Predicting board strength by X-ray scanning of logs: the impact of different measurement concepts2007Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 22, nr 1, s. 60-70Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this study was to compare the individual board strength predictions from an X-ray log scanner by using either two or four X-ray directions. The benefit of applying traceability between log and board was also studied. In total, 119 Norway spruce [Picea abies (L.) Karst.] sawlogs were scanned by an X-ray log scanner at the log sorting station of a sawmill and sawn into two centre pieces per log. Individual board traceability was enabled by following the rotational position of the log in the scanner and at the succeeding sawing. All boards were graded by a commercial strength grading machine before destructive testing was done. The resulting data were used to derive variables for building multivariate partial least squares strength prediction models. In the modelling a hierarchical modelling approach was used, where annual ring width, dry density and elasticity were also modelled. For all concepts studied the models' fit was similar. Only minor benefits could be found when using four directions and traceability compared with two directions and no traceability. One conclusion is that the result for traceability, from four directions in particular, is more sensitive for the interior knot reconstruction result. The strength prediction was on the same R2 level as for the strength grading machine

  • 4. Chiorescu, Sorin
    et al.
    Grönlund, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    The fingerprint method: using over-bark and under-bark log measurement data generated by three-dimensional log scanners in combination with radiofrequency identification tags to achieve traceability in the log yard at the sawmill2004Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 19, nr 4, s. 374-383Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the forestry-wood chain the concept and the technologies of traceability are in a mature development phase. Important advances in marking and reading techniques have been made in different parts along the forestry-wood chain. For Swedish sawmills the most critical information gap is located between the log sorting station and the saw intake, where the forest log batch identity disappears and the logs are mixed according to different sorting criteria. This study utilizes radiofrequency identification tags for automatic log marking/reading to develop a traceability system for logs, which is free of marking/reading, between the log sorting station and the saw intake, i.e. the fingerprint method. The originality of the fingerprint approach rests on the hypothesis that logs are separate entities with individual features. The results show that the log parameters and the search algorithm developed, combined with the negative influence of the measurement uncertainty due to bark thickness and bark damage, made it possible to achieve an individual separation for 57% of the tested logs.

  • 5.
    Fredriksson, Magnus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Reconstruction of Pinus Sylvestris knots using measurable log features in the Swedish Pine Stem Bank2012Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 27, nr 5, s. 481-491Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this study was to develop a method for reconstruction of parametrically described whorls and knots from data possible to extract from industrial scanning of logs, using X-ray scanners. The method was conceived using the logs in the Swedish Pine Stem Bank as a foundation, and was based on a few predictor features extracted from these logs; namely whorl volume, distance between whorls and distance between pith and surface. These features were not measured in images but calculated from existing parameterised knots. Simulated test sawing 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 could, 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 can, therefore, focus on developing a practical application of the results presented here.

  • 6. Grundberg, Stig
    et al.
    Grönlund, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Simulated grading of logs with an X-ray Log Scanner: Grading accuracy compared with manual grading1997Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 12, nr 1, s. 70-76Artikel i tidskrift (Refereegranskat)
  • 7.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Automatic quality grading of logs with TINA a gamma ray log scanner1993Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 8, s. 583-590Artikel i tidskrift (Refereegranskat)
  • 8.
    Häggqvist, Patrik
    et al.
    Luleå tekniska universitet, Institutionen för konst, kommunikation och lärande, Medier ljudteknik och upplevelseproduktion och teater.
    Leijon, Solveig Berg
    Department of Forest Resource Management, Swedish University of Agricultural Sciences.
    Lidestav, Gun
    Department of Forest Resource Management, Swedish University of Agricultural Sciences.
    Forest days as an educational method in Swedish family forestry2010Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 25, nr Suppl. 9, s. 25-32Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Swedish forest owners are a diverse group with regard to activity, education and experience of practical forestry. Urbanization and increased gender equality have also changed the composition of forest owners and their involvement in practical forestry work. Yet, many forest owners perform some kind of practical work on their property. The combination of dangerous work and untrained practitioners has led to a number of serious accidents. As a part of a larger safety campaign, a forest day for absentee forest owners living in the Stockholm area was carried out. Safety and safe working with chainsaws was a core message. To assess the immediate learning effect among different categories of forest owners, a questionnaire and a before-and-after test were used. The results show that those who knew less, female forest owners and non-chainsaw users, learned the most. The study also shows that the use of safety equipment is limited among absentee forest owners and that forest days and courses are important for their conception of safety. During the forest day, men were central experts and women appeared as servants, demonstrating the presence of a masculine hegemony. As the forest owners learned from each other it is important that professional communicators are seen to be the most reliable and trustworthy

  • 9.
    Häggqvist, Patrik
    et al.
    Luleå tekniska universitet, Institutionen för konst, kommunikation och lärande, Medier ljudteknik och upplevelseproduktion och teater.
    Leijon, Solveig Berg
    Department of Forest Resource Management, Swedish University of Agricultural Sciences, SLU.
    Lidestav, Gun
    Department of Forest Resource Management, Swedish University of Agricultural Sciences, SLU.
    Look at what they do: a revised approach to communication strategy towards private forest owners2014Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 29, nr 7, s. 697-706Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Private forest owners in Sweden and other countries are becoming an increasingly heterogeneous group as regards their experience and knowledge of forestry. Over the past decade, a number of studies have been conducted with the aim of describing different aspects of forest owners. However, little attention has been paid to the owners’ self-activity and how they learn. With the overall aim of exploring the relationship between self-activity and knowledge to use it as a starting point for new recommendations for planned communication towards forest owners, this study examines the extent and type of the work different categories of private forest owners perform, and from whom or where they learn. An analysis of data from a mail questionnaire and from the Database for Forest Owner Analysis showed that self-activity is common in all categories of owners but more frequent among male and resident forest owners. Forest owners have relatively few knowledge sources. Besides being self-taught, the most common ways of learning are from their fathers and from attending forest days. The study also shows a strong connection between self-activity and self-estimated knowledge of forestry. The recommendation for communication planning is therefore to use the extent and type of self-activity among different groups of forest owners as a point of departure for planning communication strategies.

  • 10.
    Johansson, Maria
    et al.
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Människa och teknik.
    Johansson, Kristina
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Människa och teknik.
    Andersson, Elias
    Department of Forest Resource Management, Swedish University of Agricultural Sciences, Umeå.
    #Metoo in the Swedish forest sector: testimonies from harassed women on sexualised forms of male control2018Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 33, nr 5, s. 419-425Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study adds to the literature on the gendered culture of the forest sector by examining testimonies of sexual harassment in relation to the gendering of forestry-related competence and organisations and the consequences that the sexualisation of social relations in organisations has, mainly for women. The empirical base of the study comprised testimonies within the campaign #slutavverkat published on Instagram to highlight experiences of sexual harassment of women in the Swedish forest sector. Qualitative content analysis of the testimonies suggested that the situations described in the testimonies in #slutavverkat comprise controlling actions that diminish women's power in the forest sector. Sexualised forms of male control and harassment thus work to remind women that they are first and foremost a representation of women, rather than of forestry professions and knowledge. In that sense, sexualised forms of male control and harassment are part of, rather than deviating from, the overall gendering of forestry as a men-dominated sphere. The study adds to organisational understandings and policy developments on discrimination and harassment and suggests that researchers and policy-makers interested in reducing inequality in forestry need to pay more attention to issues of harassment and sexualisation of social relations.

  • 11.
    Lindahl, Karin Beland
    et al.
    Department of Urban and Rural Development, Swedish University of Agricultural Sciences, Uppsala.
    Westholm, Erik
    Department of Urban and Rural Development, Swedish University of Agricultural Sciences, Uppsala.
    Future forests: Perceptions and strategies of key actors2012Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 27, nr 2, s. 154-163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper investigates how key actors perceive the future of the forest sector: how they position themselves in relation to climate, energy and demography related trends. Actors’ perceptions of future challenges and opportunities influence their choice of strategy and action. Actors’ relative capacity to realise their visions, in turn, shape future forest use. Frame analysis is used to explore selected actor's perceptions and strategies and the existence of major divisions, i.e. frame conflicts. Empirically, the study is based on the case of Sweden as a typical boreal forest producing region. Actors’ perceptions of the challenges facing the forest sector diverge widely. Yet, most actors see the future of the forest sector as linked to broader issues of climate mitigation and energy transition. These issues trigger fundamental discussions about social change and the role of forests in future society. A major division separates actors who perceive biomass supply as unlimited, or at least not constraining, and those who stress scarcity and re-distribution of resources. This difference, or frame conflict, is reflected in actors’ forest related strategies and may fuel future forest debates and conflicts.

  • 12.
    Lundmark, Robert
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Samhällsvetenskap.
    Cost structure of and the competition for forest-based biomass2006Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 21, nr 3, s. 272-280Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biomass has become a popular alternative to satisfy expanding energy demand and as a substitute for fossil fuels and phased-out nuclear energy in Europe. The European Union White Paper stipulates that the utilization of biomass shall increase to 1566 TWh by 2010. However it is often overlooked that the forest resources are already, to a large extent, used by the forest industries. When promoting biomass for energy generation the consequences for the forest industries also need to be considered. Sweden is an excellent case study, as there are vast quantities of forest resources, nuclear power is starting to be phased out, there are restrictions on expanding hydropower and the political desire exists to "set an example" with respect to carbon dioxide emissions. This paper attempts to estimate and analyse the supply of two types of forest resource, namely, roundwood and harvesting residues derived from final harvesting and commercial thinnings. Two separate supply curves are estimated: one forroundwood and one for harvesting residues. The cost structure is based on an economic-engineering approach where the separate cost components are constructed from the lowest cost element into aggregates for labour, capital, materials and overhead costs for each forest resource. The results indicate an unutilized economic supply of 12 TWh of harvesting residues in Sweden. However, after these 12 TWh have been recovered it becomes more profitable to use roundwood for energy purposes than to continue extracting further amounts of harvesting residues.

  • 13.
    Lundmark, Robert
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Samhällsvetenskap.
    Investment behaviour in the European pulp and paper industry2003Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 18, nr 2, s. 184-192Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study analysed the location of investments in the European pulp and paper industry. Three continuous investment models were estimated allowing for fixed as well as random effects using data for 10 European countries over the period 1978-1995. The results indicated that labour wages, market size and agglomeration effects were the most important determinants of investment levels. The impacts of raw material prices were somewhat ambiguous. However, in the long run waste paper availability seems to matter in the sense of attracting investments. A comparison of the economic significance of changes in the costs of input factors with changes in the market size indicated that proximity to output markets had a larger impact on the decision to invest than proximity to abundant raw materials or cheap access to electricity and labour. Furthermore, the agglomeration coefficient indicated that the power of sunk costs is important.

  • 14.
    Lundmark, Robert
    et al.
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Samhällsvetenskap.
    Shahrammehr, Shima
    Sweden’s import substitution possibilities for roundwood2011Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 26, nr 2, s. 146-153Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The substitution possibilities between imports and domestically produced goods and commodities are usually measured by Armington elasticities. These elasticities are essential parameters that have large affect on the result of trade models. The purpose of this study is to estimate disaggregated Armington elasticities for different segments of roundwood for Sweden. The data-set spans 1967-2007. The time-series are tested for non-stationary properties. The estimation fails to produce statistically significant elasticities for pulpwood but for sawlogs the estimated elasticity is 3.2. This is a relatively high estimate and indicates that imported and domestic sawlogs are easily substituted. In addition, event cases on the effect of various surrounding events (the fall of the Soviet Union and Sweden's membership in the EU) on the estimated Armington elasticities are tested. The results for these event cases indicate that the substitutability between imported and domestic pulpwood increased both with the fall of the Soviet Union and Sweden's membership in the EU. However, no such pattern could be observed for sawlogs.

  • 15.
    Lycken, Anders
    et al.
    Luleå tekniska universitet.
    Oja, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    A multivariate approach to automatic grading of Pinus sylvestris sawn timber2006Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 21, nr 2, s. 167-174Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this study was to create an easier way to handle the often complicated and intricate situations with which the operator of an automatic grading system is faced each time a change to the grading rules is proposed. The scope of the study was the possibility of a holistic method of automatic appearance grading of sawn wood similar to manual grading and based on multivariate statistics. The study was based on 90 Scots pine ( Pinus sylvestris L.) sawlogs. The logs were sawn and the boards were scanned and manually graded. The result of the manual grading was defined as the true grade. Models for prediction of board grade based on aggregated defect variables were calibrated using partial least squares regression. The classification based on the multivariate models resulted in 80-85% of the boards being correctly graded according to the manual grading. In conclusion, this paper shows that a multivariate statistical approach for grading timber is a possible way to simplify the process of grading and to customize the grading rules when using an automatic grading system

  • 16.
    Nordmark, Urban
    Luleå tekniska universitet.
    Knot identification from CT images of young Pinus sylvestris sawlogs using artificial neural networks2002Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 17, nr 1, s. 72-78Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The value of solid wood products is to a large extent determined by the sizes, types and distribution of the knots in the products. Hence there is a great interest in describing the internal knot structure of individual logs. The Swedish Stem Bank has been extensively used for modelling the interior knot structure of Scots pine ( Pinus sylvestris L.) and for simulating the outcome of sawing operations. The stem bank holds parametric descriptions, extracted from computer tomography (CT) imagery, of mature trees. To enlarge the stem bank with trees from younger stands, a better method for extracting the knot properties from the CT images is needed. In this study, artificial neural networks were used for segmenting and classifying knots in transverse CT images of a 30-year-old Scots pine. The cross-validated prediction rate of correctly classified pixels was 95.9% ±1.2%. Classified knots were distinctly separated. Misclassifications were mainly located in the border areas between knots and clear

  • 17.
    Nordmark, Urban
    Luleå tekniska universitet.
    Models of knots and log geometry of young Pinus sylvestris sawlogs extracted from computed tomographic images2003Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 18, nr 2, s. 168-175Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The value of solid wood products is largely determined by the sizes, types and distribution of the knots in the products. Hence, there is a great interest in describing the internal knot structure of individual logs. The Swedish Stem Bank has been extensively used for modelling the interior knot structure of Scots pine (Pinus sylvestris L.) and for simulating the outcome of sawing operations. The stem bank holds parametric descriptions, extracted from computed tomographic (CT) imagery, of mature trees. A method for extracting parametric descriptions, in compliance with the stem bank, from young Scots pine sawlogs is presented in this study. A key step in the algorithm is the use of an artificial neural network to find knots in the CT images. The accuracy of the extracted descriptions was evaluated by comparing the size and position of knots measured on 10 real boards with corresponding boards simulated based on the description. The study showed that the number of knots on the real boards was well predicted (R2 = 0.90). The differences in tangential and longitudinal position were 0.3 ± 3.6 mm and 1.6 ± 4.2 mm, respectively. The differences in tangential and longitudinal diameter were 0.6 ± 4.0 mm and -0.6 ± 3.9 mm, respectively. Knot diameters were more accurately predicted on boards distant from the pith than on boards close to pith.

  • 18.
    Nordmark, Urban
    et al.
    Luleå tekniska universitet.
    Oja, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Prediction of board values in Pinus sylvestris sawlogs using X-ray scanning and optical three-dimensional scanning of stems2004Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 19, nr 5, s. 473-480Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As the sawmill industry strives towards customer orientation, the need for sorting of logs according to quality has been recognized, and automatic sorting based on measurements by three-dimensional (3D) optical log scanners has been implemented at sawmills. There is even a small number of sawmills using the X-ray log scanner for automatic log-sorting. At the log-sorting stage, the potential of the raw material to fulfil the needs has already been reduced by the decisions taken when the trees were bucked (cross-cut) into logs. Thus, the application of predictions of the boards' properties at the bucking stage is desirable. This study investigates the possibility of predicting board values from logs based on 3D scanning alone and 3D scanning in combination with X-ray scanning of stems. This study is based on 628 logs scanned by computed tomography that make up the Swedish Pine Stem Bank. Simulated sawing of the logs gave product values for each log. Prediction models on product value were adapted using partial least squares regression and x-variables derived from the properties of the logs and their original stems, measurable with a 3D log scanner and the X-ray LogScanner. The results were promising. Using a 3D scanner alone, R2 was 0.68, and using a 3D scanner in combination with an X-ray LogScanner, R2 was 0.72.

  • 19.
    Oja, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    A comparison between three different methods of measuring knot parameters in Picea abies1997Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 12, nr 3, s. 311-315Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Both foresters and sawmillers are interested in the knot structure of trees; in particular, position and number of knots, knot diameter, knot length and dead knot border. For research purposes, it is possible today to carry out non-destructive measurements using computer tomography (CT) and image analysis. The aim of this study was to measure knot parameters on Norway spruce (Picea abies (L.) Karst.) using a non-destructive method developed for Scots pine (Pinus sylvestris L.), and to compare the results of this method with the results of two different destructive methods. In order to do this, two Norway spruce stems were scanned by CT. Then five logs from one stem were cut into flitches 20 mm thick and the defects on the sawn surfaces were scanned manually. The other stem was cut just above every whorl and then each knot was split through its centre and the knot parameters were measured manually. The study showed that the CT method compares well with the destructive methods. It is a reasonably fast, non-destructive method which measures position and diameter of knots and detects larger knots with acceptable accuracy. The study also showed that a large number of smaller knots were not found by the CT method and that the CT method measured knot length and dead knot border with low accuracy. This means that the CT method has to be adjusted to Norway spruce in order to improve its ability to measure knot length and dead knot border and to detect smaller knots.

  • 20.
    Oja, Johan
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Grundberg, Stig
    Fredriksson, Johan
    Swedish Institute for Wood Technology Research.
    Berg, Per
    Swedish Institute for Wood Technology Research.
    Automatic grading of sawlogs: a comparison between X-ray scanning, optical three-dimensional scanning and combinations of both methods2004Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 191, nr 1, s. 89-95Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As sawmills become increasingly efficient, the importance of focusing on value recovery becomes obvious. To maximize value recovery, sawmills require the ability to sort logs according to quality. This study compares four different combinations of three-dimensional (3D) and X-ray scanning that can be used to grade logs automatically. The study was based on 135 Scots pine (Pinus sylvestris L.) logs that had been scanned with both a 3D scanner and an X-ray scanner with two X-ray sources. The percentage of boards with correct grade sawn from automatically graded logs varied from 57% when using only 3D scanning to 66% when using a combination of 3D scanning and X-ray scanning in two directions. The highest possible result, with ideal log grading, was 81%. The result also shows that the combination of a 3D scanner and one X-ray direction results in higher accuracy than a scanner based on two X-ray directions

  • 21. Oja, Johan
    et al.
    Grundberg, Stig
    Grönlund, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Measuring the outer shape of Pinus sylvestris saw logs with an x-ray LogScanner1998Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 13, nr 3, s. 340-347Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The accuracy of measuring the outer shape of Scots pine (Pinus sylvestris L.) saw logs with an X-ray LogScanner has been compared with the accuracy of using a 2-axis optical scanner, a 3-axis optical scanner and an ideal 3-D optical scanner. The different scanners were simulated using computed tomography (CT) data from the Swedish Stem Bank. The outer shape of 60 saw logs was measured every third centimeter. The error attributable to bark when using optical scanners was simulated separately. The results from the simulations showed that when measuring the outer shape on bark, the X-ray LogScanner facilitated measurement of the minimum shadow diameter with the same accuracy as with a 3-D optical scanner. The results also showed that the potential of combining the X-ray LogScanner with a 3-D optical scanner should be investigated

  • 22. Oja, Johan
    et al.
    Grundberg, Stig
    Grönlund, Anders
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Predicting the stiffness of sawn products by X-ray scanning of Norway spruce saw logs2001Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 16, nr 1, s. 88-96Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of the study was to investigate the possibility of strength grading Norway spruce [Picea abies (L.) Karst.] saw logs on the basis of simulated X-ray LogScanner measurements and to evaluate the potential accuracy of X-ray LogScanner measurements of green heartwood density and percentage of heartwood. The study was based on 272 logs for strength grading and 29 logs for measurements of green heartwood density and percentage of heartwood. The logs were scanned using computed tomography (CT). After sawing, the modulus of elasticity (MOE) of the centre boards was measured using a strength-grading machine. The CT images were used for simulations of an X-ray LogScanner, resulting in simulated measurements of different variables such as diameter, taper, percentage of heartwood, density and density variations. Multivariate models for prediction of MOE were then calibrated using partial least squares (PLS) regression. The MOE of a log was defined as the mean value of the MOE of the two centre boards. The study showed that the simulated X-ray LogScanner measured the percentage of heartwood and green heartwood density with relatively high accuracy (R2 = 0.94 and R2 = 0.73, respectively, after removing two outliers) and that these and other variables measured by the simulated X-ray LogScanner could be used to predict the stiffness of the centre boards. These predictions were used to sort the logs according to the predicted MOE. When sorting out 50% of the logs (''high-strength'' logs), the percentage of C30 boards increased from 73% (all logs in the study) to 100% (only ''high-strength'' logs). The rest of the logs could then be divided into two groups, one of them with 100% C24 and C30 boards.

  • 23.
    Olofsson, Casper
    et al.
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Samhällsvetenskap.
    Wadsten, Joel
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Samhällsvetenskap.
    Lundmark, Robert
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Samhällsvetenskap.
    European trade and projections in forest-based feed-stocks2018Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 33, nr 8, s. 809-814Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this study is to estimate the intra EU trade value of wood products and examine the factors affecting the trade flow. A gravity model is used to estimate the factors affecting the trade flow. The study uses a panel data set, with fixed effects, on trade in two forest products between 28 EU member countries over the period 2005–2014. The forest products are woodchips and particles (HS4401) and industrial roundwood (HS4403). For HS4401, the result suggests that the GDP of both the exporting and importing countries affect the trade flow positively (0.64 and 0.36, respectively). For HS4403, the GDP of the exporting countries affect have a negative effect (−0.69), while the GDP of the importing countries have a positive effect (0.80). In a second step, the estimated parameters are used to forecast the trade up until year 2030. The forecast suggests an increase in the trade by 47 per cent. This suggests an improved efficiency in reaching the EU climate and energy targets. That is, the trade in biofuels is expected to increase due to economic growth, which in turn works towards achieving the renewable and CO2 emission targets in Europe.

  • 24.
    Olofsson, Elias
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Samhällsvetenskap.
    Regional effects of a green steel industry: Fuel substitution and feedstock competition2019Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 34, nr 1, s. 29-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Forestry and forest industry sectors have vital roles for many regional economies. Consequently, it is important to understand how the introduction of the iron and steel industry (ISI) as a new large consumer of woody materials may affect existing feedstock markets. The use of metallurgical coal can partially or fully be substituted by refined biomass. To analyze the potential consequences of a new woody consumer on regional markets, three regions in northern Sweden and Finland are used as a case. A regional partial equilibrium model is developed, the Norrbotten County Forest Sector Model (NCFSM), and applied on three different scenarios. The purpose of the study is to analyze the intra- and inter-regional effects increased competition for woody materials may have on regional markets and on the economic well-being of the regions. The result suggest that the total welfare effect is relatively small, however, some regional welfare distributional effects are observed. Additionally, the price of roundwood will only be moderately affected if the ISI sector switch from fossil fuels to refined woody biomass. However, secondary woody materials, i.e. by-products and harvesting residues, will experience larger price shifts.

  • 25.
    Sandberg, Dick
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Vaziri, Mojgan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Trischler, Johann
    Linnæus University, Forestry and Wood Technology.
    Öhman, Micael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    The role of the wood mechanical industry in the Swedish forest industry cluster2014Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 29, nr 4, s. 352-359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The forest and forest products form one of the most important basis for the transfer to a biobased economy in Sweden. About 75% of the area covered by forest in Sweden is used industrially to produce raw material for the wood-refining industries. Every year, this cluster uses 75 million m3 of roundwood and has an export value of € 12 billion. This review paper is devoted to the wood mechanical industry, i.e. the industry which turns the forest into sawn timber, packaging, construction wood, furniture and interior fittings. The sawmills consume about half of the volume of softwood which is felled, and about two thirds of the sawn timber goes to export without any further refining within the country. Nevertheless, in spite of the relatively low degree of refinement in the sawmill and the fact that the sawmills in general over time have a very low profitability, they are responsible for 70–80% of the forest owners' profits on the sale of timber. An increased upgrading of the sawn timber within the country is desirable from a national economic viewpoint – increased employment opportunities, increased export income etc. It should then in the first place be for products with a higher added value, such as furniture and fittings. Today, the refinement value is 15–20 times higher for products from joinery and furniture industries compared that of the sawn timber and the added value of the wood within the building industry is only about 1.5 times.

  • 26. Skog, Johan
    et al.
    Oja, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Density measurements in Pinus sylvestris sawlogs combining X-rayand three-dimensional scanning2010Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 25, nr 5, s. 470-481Artikel i tidskrift (Refereegranskat)
    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.

  • 27. Skog, Johan
    et al.
    Oja, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Heartwood diameter measurements in Pinus sylvestris sawlogs combining X-ray and three-dimensional scanning2009Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 24, nr 1, s. 182-188Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quality sorting of sawlogs based on three-dimensional (3D) or X-ray scanning or a multivariate combination of variables from both methods may be used to decrease the production of off-grade products carrying unwanted combinations of dimension and grade. There is, however, potential for further improving the sorting accuracy if 3D and X-ray raw data are combined at an early stage using path length compensation. From the measured 3D shape, a good estimate of the length of each X-ray path through the log can be made, enabling the calculation of a log density profile from the measured X-ray attenuation. The effect of this technique on heartwood diameter measurements of 423 Scots pine (Pinus sylvestris L.) logs was evaluated. By the addition of 3D data to the X-ray data it was possible to raise the predictability of the heartwood diameter from R 2=0.84 to 0.95 and to improve the root mean square error from 17 mm to 9.3 mm, primarily because of the enhanced contrast between heartwood and sapwood.

  • 28.
    Öhman, Micael
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Grade prediction of Pinus sylvestris logs with the aid of a radiograph image log1998Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 13, s. 83-89Artikel i tidskrift (Refereegranskat)
  • 29.
    Öhman, Micael
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Nyström, Jan
    Measurement of green plank shape for prediction and elimination of compression wood2002Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 17, nr 4, s. 377-384Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this study was to predict the amount and the distribution of compression wood (CW) within a Norway spruce [Picea abies (L.) Karst.] plank based on green plank curvature. The findings indicated a possibility of predicting the longitudinal distribution of CW from the green plank curvature. Areas free from CW showed a typical concave shape in relation to the centre of the log, while CW was present when a convex shape was shown. The larger the magnitude of convex curvature, the higher the concentrations of CW that could be found, and a larger fraction of dried planks was rejected due to excessive warp. This study also determined what information can be used to eliminate areas of high concentrations of CW by cutting and how cutting affects the grading results with respect to warp. Over 50% of the plank length showing a high concentration of CW (> 30% of the cross-cut volume) was successfully cut off. Cutting strategies based on predicted CW concentrations resulted in a 10-40% increase in accepted plank length.

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