| 1. |
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| 2. |
- Andersson, Linus, 1979-, et al.
(author)
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Effects of Task Demands on Olfactory, Auditory, and Visual Event-Related Potentials Suggest Similar Top-Down Modulation Across Senses
- 2018
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In: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 43:2, s. 129-134
-
Journal article (peer-reviewed)abstract
- A widely held view is that top-down modulation of sensory information relies on an amodal control network that acts through the thalamus to regulate incoming signals. Olfaction lacks a direct thalamic projection, which suggests that it may differ from other modalities in this regard. We investigated the late positive complex (LPC) amplitudes of event-related potentials (ERP) from 28 participants, elicited by intensity-matched olfactory, auditory and visual stimuli, during a condition of focused attention, a neutral condition, and a condition in which stimuli were to be actively ignored. Amplitudes were largest during the attend condition, lowest during the ignore condition, with the neutral condition in between. A Bayesian analysis resulted in strong evidence for similar effects of task across sensory modalities. We conclude that olfaction, despite its unique neural projections, does not differ from audition and vision in terms of task-dependent neural modulation of the LPC.
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| 3. |
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| 4. |
- Borg, Markus, et al.
(author)
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Do Take it Personal : It's Not What You Say, It's Who (and Where) You Are!
- 2016. - 6
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In: Tiny Transactions on Computer Science. ; 4
-
Journal article (peer-reviewed)abstract
- Issue management in market-driven software projects is constantly under time pressure. A limited set of developers must share their time between developing features for the next release and resolving reported issues. Project managers need to find the appropriate balance between a high quality product and fast time to market. We study a telecom company in Sweden developing embedded systems for a consumer market. The project managers report that developers resolve approximately 10% of the issues reported during a project. Consequently, it is critical to properly prioritize the issues to receive the best possible return on investment, and above all to remove all bugs that might impact the market's reception of the product. We use machine learning to investigate what features of an issue report are the best predictors of changes to production code during its corresponding resolution. After removing all features jeopardizing the confidentiality of individual engineers, the issue reports are characterized by 19 features (apart from text). We extract 80,000 issue reports, an equal mix of positive and negative examples, and train a Bayesian Network classifier [2], obtaining 73% classification accuracy. Moreover, it reveals that the feature with the highest predictive value is from which physical site the issue was submitted. The general priority feature however, is only ranked 17 out of 19, whereas the submitting team is ranked 12. Our findings confirm a suspicion in the company: the priority set by the issue submitter is indeed a poor predictor of a future code change.
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| 5. |
- Dyrek, Achrène, et al.
(author)
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SO2, silicate clouds, but no CH4 detected in a warm Neptune
- 2024
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In: Nature. - 0028-0836 .- 1476-4687. ; 625, s. 51-54
-
Journal article (peer-reviewed)abstract
- WASP-107b is a warm (approximately 740 K) transiting planet with a Neptune-like mass of roughly 30.5 M⊕ and Jupiter-like radius of about 0.94 RJ (refs. 1,2), whose extended atmosphere is eroding3. Previous observations showed evidence for water vapour and a thick, high-altitude condensate layer in the atmosphere of WASP-107b (refs. 4,5). Recently, photochemically produced sulfur dioxide (SO2) was detected in the atmosphere of a hot (about 1,200 K) Saturn-mass planet from transmission spectroscopy near 4.05 μm (refs. 6,7), but for temperatures below about 1,000 K, sulfur is predicted to preferably form sulfur allotropes instead of SO2 (refs. 8,9,10). Here we report the 9σ detection of two fundamental vibration bands of SO2, at 7.35 μm and 8.69 μm, in the transmission spectrum of WASP-107b using the Mid-Infrared Instrument (MIRI) of JWST. This discovery establishes WASP-107b as the second irradiated exoplanet with confirmed photochemistry, extending the temperature range of exoplanets exhibiting detected photochemistry from about 1,200 K down to about 740 K. Furthermore, our spectral analysis reveals the presence of silicate clouds, which are strongly favoured (around 7σ) over simpler cloud set-ups. Furthermore, water is detected (around 12σ) but methane is not. These findings provide evidence of disequilibrium chemistry and indicate a dynamically active atmosphere with a super-solar metallicity.
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| 6. |
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| 7. |
- Ericsson, Olle, et al.
(author)
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Clinical validation of a novel automated cell-free DNA screening assay for trisomies 21, 13, and 18 in maternal plasma.
- 2019
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In: Prenatal diagnosis. - : Wiley. - 1097-0223 .- 0197-3851. ; 39:11, s. 1011-1015
-
Journal article (peer-reviewed)abstract
- To evaluate clinical performance of a new automated cell-free (cf)DNA assay in maternal plasma screening for trisomies 21, 18, and 13, and to determine fetal sex.Maternal plasma samples from 1200 singleton pregnancies were analyzed with a new non-sequencing cfDNA method, which is based on imaging and counting specific chromosome targets. Reference outcomes were determined by either cytogenetic testing, of amniotic fluid or chorionic villi, or clinical examination of neonates.The samples examined included 158 fetal aneuploidies. Sensitivity was 100% (112/112) for trisomy 21, 89% (32/36) for trisomy 18, and 100% (10/10) for trisomy 13. The respective specificities were 100%, 99.5%, and 99.9%. There were five first pass failures (0.4%), all in unaffected pregnancies. Sex classification was performed on 979 of the samples and 99.6% (975/979) provided a concordant result.The new automated cfDNA assay has high sensitivity and specificity for trisomies 21, 18, and 13 and accurate classification of fetal sex, while maintaining a low failure rate. The study demonstrated that cfDNA testing can be simplified and automated to reduce cost and thereby enabling wider population-based screening.
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| 8. |
- Huber, Johannes Albert Josef, PhD, 1989-, et al.
(author)
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Evaluation of Knots and Fibre Orientation by Gradient Analysis in X-ray Computed Tomography Images of Wood
- 2023
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In: CompWood2023: Computational Methods in Wood Mechanics. - Barcelona : International Center for Numerical Methods in Engineering (CIMNE). - 9788412322279 ; , s. 143-144
-
Conference paper (other academic/artistic)abstract
- The mechanical properties of wood are governed by growth-dependent structures on themicro- and macroscopic level, which are subject to natural variation. Numerical modelsof wood on a scale of individual pieces of sawn timber may need to account e.g. for thegrowth ring orientation or the presence of knots and their effects on the local materialorientation, i.e. the variation of the fibre coordinate system (FCS). The FCS is composedof the mutually orthogonal longitudinal (l), radial (r) and tangential (t) directions. Agrowth surface represents a region of equal age, i.e. a former growth front of the tree,and at each point on a growth surface, the r direction consequently represents the surfacenormal. Growth surfaces surrounding a knot are usually approximated by analyticalsurfaces, onto which the l direction is modelled by hydrodynamic flow fields in lateral andby polynomials in the vertical direction, like in [1].A data-driven method used for detecting the location of knots and eliciting the in-planeprojection of the l direction on the surface of sawn timber is optical scanning combinedwith laser tracheid scanning [2]. A disadvantage of this method is that the internalstructure of the scanned timber remains unknown and needs to be extrapolated, againbased on assumptions of growth in wood. X-ray computed tomography (CT) of woodprovides images of the internal density distribution from which features like the pith, thegrowth rings, knots and defects can be extracted by image analysis.In a recent study [3], the local FCSs around knots were reconstructed by density gradientanalysis in CT images, on which finite element models were based for predicting thebending behaviour of sawn timber. Growth surfaces in wood represent regions of nearlyconstant density and can therefore be analysed in CT images by gradient-based methods.The goal of the present study was therefore to study how the gradient of the density fieldderived from CT images of wood can be used to determine growth surfaces, the region ofknots, the border between dead and live knot, and the locally varying FCSs.The material studied was comprised of small log sections of Scots pine (pinus sylvestris)(approximate diameters of 50 mm - 300 mm and length 250 mm) containing knot whorls,which were dried to fibre saturation. CT scans were acquired at a voxel size of 0.5 × 0.5 ×0.5 mm3 yielding a 3D image J(x, y, z). After scanning, the sections were cut throughthe centrelines of the knots and manual measurements were conducted of the dead knotborder, i.e. the position along the boundary of a knot after which a knot died off. At this border, the diameter of the knot stops increasing and the surrounding fibres grow aroundthe knot rather than merging with it. As the tree continues to grow, this will eventuallylead to bark being encased around the knot inside the tree.A purely data-driven analysis was performed based on the partial derivatives Jx , Jy , Jz ,from which the gradient structure tensor (GST) was constructed, see equation 1, where wσ is a Gaussian convolutional kernel. The eigenvalues and eigenvectors of the GSTwere extracted for each voxel and the resulting vector field was used in the subsequentanalyses. Equivalently, second order derivatives were studied to study curvature.The results indicate that gradient-based analyses on CT images of wood can be usedto approximate the locally varying FCSs around knots, see Figure 1 and that they mayfacilitate the determination of the region of dead and live knots.
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| 9. |
- Jensen, Patrik, et al.
(author)
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Reducing complexity of customized prefabricated buildings through modularisation and it support
- 2008
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In: [Host publication title missing]. ; , s. 429-437
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Conference paper (peer-reviewed)abstract
- Many companies in Sweden using prefabricating strategies are currently meeting the ever increasing customer requirements with ad-hoc solutions that do not fit their production system. This is causing bottlenecks and lower profit margins as a consequence. One solution to the problem is to re-engineer their building systems according to modularization principles used in the manufacturing industries, which have adapted their production to be able to meet mass-customization. This paper describes the first part in study of modularization of building systems and if methods used in themanufacturing industry can be adapted to the building industry. The Swedish construction industries using prefabrication strategies are mainly project oriented, and needs todevelop a more product oriented development process to benefit from the values that modularization can give.It is also obvious that it is impossible to introduce modularization methods used in manufacturing industries ifdesign requirements are incomplete or changing from project to project. It is therefore essential that theproduct owner owns the whole process as well. Varying customers’ demands can to some extent be handledusing modularization principles. However, we don’t believe that one solution fit’s all; therefore it is essential to target a specific segment of the market. The cost for the development of such modularized building systemfor the targeted segment of customer must be evaluated against the possible market share.
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| 10. |
- Jensen, Patrik, et al.
(author)
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Reducing complexity of customized prefabricated buildings through modularization and IT support
- 2008
-
In: CIB-W78. - : Universidad de Talca. - 9789563193619 ; , s. 429-437
-
Conference paper (peer-reviewed)abstract
- Many companies in Sweden using prefabricating strategies, are currently meeting the ever increasing customer requirements with ad-hoc solutions that do not fit their production system causing bottlenecks and lower profit margins as a consequence. One solution to the problem has been to re-engineer their building systems according to modularization principles used in the manufacturing industries that have adapted their production to mass-customization. This paper describes the first part in study of modularization of building systems and if methods used in the manufacturing industry can be adapted to the building industry. Today the Swedish Construction Industries are mainly project oriented, and needs to go to a more product oriented development to benefit from the values that modularization can give. It is also obvious that it is impossible to introduce modularization methods used in manufacturing industries if design requirements are incomplete or changing from project to project. It is therefore essential that the product owner owns the whole process as well. Varying customers' demands can to some extent be handled using modularization principles. However, we don't believe that one solution fit's all; therefore it is essential to target a specific segment of the market. The cost for the development of such modularized building system for the targeted segment of customer must be evaluated against the possible market share.
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| 11. |
- Malmgren, Linus, et al.
(author)
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Product modeling of configurable building systems - a case study
- 2010
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In: Journal of Information Technology in Construction. - 1874-4753. ; 15, s. 354-368
-
Journal article (peer-reviewed)abstract
- This paper investigates a Swedish house manufactures building system regarding the documentation and information structures. The aim is to evaluate how product modeling technology can be used to facilitate product customization. By dividing the product in four different views the complexity of the product can be reduced and each view represent the interest of customer, engineering, production and assembly respectively. The analysis shows that the connections between the different view, i.e. the information transfer, is an area for potential improvements and little attention has been devoted to transfer information upstream from manufacturing and engineering to the customer view. The lack of information transfer can often lead to ad-hoc solutions in the customization process. We believe that successful cooperation and information exchange between these four views is the key to future development and customize-to-order configuration.
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| 12. |
- Malmgren, Linus, et al.
(author)
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Product modeling of configurable building systems - A case study
- 2011
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In: Electronic journal of information technology in construction. - 1403-6835 .- 1400-6529. ; 16:May, s. 697-712
-
Journal article (peer-reviewed)abstract
- This paper investigates a Swedish house manufactures building system regarding the documentation and information structures. The aim is to evaluate how product modeling technology can be used to facilitate product customization. By dividing the product in four different views the complexity of the product can be reduced and each view represent the interest of customer, engineering, production and assembly respectively. The analysis shows that the connections between the different view, i.e. the information transfer, is an area for potential improvements and little attention has been devoted to transfer information upstream from manufacturing and engineering to the customer view. The lack of information transfer can often lead to ad-hoc solutions in the customization process. We believe that successful cooperation and information exchange between these four views is the key to future development and customize-to-order configuration.
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| 13. |
- Mishra, Rajesh, 1973-, et al.
(author)
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A conformationally isoformic thermophilic protein with high kinetic unfolding barriers
- 2008
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In: Cellular and Molecular Life Sciences (CMLS). - : Springer Science and Business Media LLC. - 1420-682X .- 1420-9071. ; 65:5, s. 827-839
-
Journal article (peer-reviewed)abstract
- The basis for the stability of thermophilic proteins is of fundamental interest for extremophile biology. We investigated the folding and unfolding processes of the homotetrameric Thermoanaerobacter brockii alcohol dehydrogenase (TBADH). TBADH subunits were 4.8 kcal/mol less stable towards guanidinium chloride (GdmCl) unfolding compared to urea, indicating ionic modulation of TBADH stability. Strongly denaturing conditions promoted mono-exponential unfolding kinetics with linear dependence on denaturant concentration. Here TBADH unfolded >40-fold slower when extrapolated from urea as compared to GdmCl unfolding. A marked unfolding hysteresis was shown when comparing refolding and unfolding in urea. An unusual biphasic unfolding trajectory with an exceptionally slow phase at intermediate concentrations of GdmCl and urea was also observed. We advocate that TBADH forms two distinctly different tetrameric isoforms, and likely an ensemble of native states. This unusual supramolecular folding behavior has been shown responsible for formation of amyloidotic yeast prion strains and can have functional importance for TBADH. © 2008 Birkhaueser.
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| 14. |
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| 15. |
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| 16. |
- Nicholls, Ian A., et al.
(author)
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Can we rationally design molecularly imprinted polymers?
- 2001
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In: Analytica Chimica Acta. ; 435:1, s. 9-18
-
Journal article (peer-reviewed)abstract
- The nearly exponential growth in the molecular imprinting literature has to a large extent been fuelled by an increasing awareness of the potential of molecular imprinting based technologies. Despite the acceptance of the technique by cognate disciplines and the demonstration of its usefulness in a number of enabling technologies, relatively little is known about the molecular level events underlying the imprinting process and subsequent recognition events. What rules govern imprint formation? Can we use such rules to rationally design molecularly imprinted polymers?
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| 17. |
- Nordin, Steven, et al.
(author)
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Evaluation of auditory, visual and olfactory event-related potentials for comparing interspersed- and single-stimulus paradigms
- 2011
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In: International Journal of Psychophysiology. - : Elsevier. - 0167-8760 .- 1872-7697. ; 81:3, s. 252-262
-
Journal article (peer-reviewed)abstract
- Background: An interspersed-stimulus paradigm (ISP) for event-related potential (ERP) recordings in which different sensory modality stimuli are presented within the same test session was developed to minimize recording time and facilitate modality comparison. The present study compared the ISP with a single-stimulus paradigm (SSP), using auditory, visual, and olfactory stimuli. Method: Normal participants (n=16) were assessed on two independent test occasions to obtain data on inter-paradigm and test-retest reliability. Peak amplitude/latency and area measures were obtained for the N1, P2 and P3 peaks for each paradigm. Results: Except for larger auditory and visual P3 peaks and smaller visual P2 peaks in the ISP, no significant differences in amplitudes or latencies were found between the two paradigms. Correlation coef ficients between paradigms were generally fairly high (amplitude mean r=0.76; latency r=0.42). Test–retest reliability within paradigms for amplitudes (ISP r=0.70; SSP r=0.68) and latencies (ISP r=0.44; SSP r=0.42) was similar across paradigms. Conclusion: Thefindings suggest that the ISP, compared to the SSP, produces, in general, highly comparable auditory, visual, and olfactory peak amplitudes and latencies, and comparable reliability estimates, even though the ISP takes much less time to record (25 vs. 50 min). The larger auditory and visual P3 peaks and smaller visual P2 peaks in the ISP may be attributable to a less predictable stimulus environment. Thus, this method enables systematic comparisons of ERP peaks across sensory modalities while reducing testing time. Practical implications are discussed.
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| 18. |
- Olofsson, Dan, et al.
(author)
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Mera rätt råvara 2.0 : Slutrapport
- 2021
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Reports (other academic/artistic)abstract
- På den japanska limträmarknaden uppskattas den norrländska furan p.g.a. dess utseende såväl som dess höga hållfasthet. Produkten benämns Lamina och har sedan 15 år tillbaka växt från en liten obetydlig andel till att idag stå för ett stort bidrag för många furusågverk i Norrland. Det som skiljer den japanska marknaden mot den europeiska är dess önskemål om speciella längder som vi traditionellt inte tillverkar på sågverken. Ska önskemålen uppfyllas krävs det även att apteringen i skogen följer med. Tyvärr är inte alla stockar tillräckligt bra för att uppfylla de styrkekrav som krävs för den japanska marknaden vilket gör att stockar som inte klarar dessa måste sorteras bort och användas för andra marknader. Resultatet av de bortsorterade stockarna är att dessa då får fel längd för den alternativa marknaden och måste då korrigeras med ett extra avkap. Det är därför det är viktigt att så bra det bara går försöka lokalisera vilka avverkningar som innehåller höga andelar av vissa produkter, i detta fall Lamina, och utifrån den informationen styra aptering mot kundönskemål för att skapa mest möjliga virkesvärde. Inom ramen för projektet Mera Rätt Råvara togs en indikator fram där data från de skogliga systemen, baserat på uppgifter som inhämtats och bedömts i fält i samband med avverkningsplanering, används föra att prediktera hållfastheten. Detta projekt är en förlängning på det arbetet och syftar till att förstå mer om korrelationen mellan trädens egenskaper och sågverksprodukternas egenskaper. Mer specifikt har arbetet handlat om att förfina och utvärdera indikatorn i olika typer av skogar med avseende på framför allt ålder. Projektets resultat visar att indikatorn med god precision klarat av att förutse ifall avverkningen är lämpad för produkter för den japanska marknaden. Av de åtta testavverkningar som gjorts låg sju av dessa med ett utfall på mellan 93 - 99% laminakvalitet i timmersorteringen inom det specifika dimensionsintervallet som produkten tas ut i. Alltså mindre än 7% klarade inte av de japanska kraven. Detta kan jämföras med utfallet under år 2020 utan styrning med hjälp av indikatorn. Där låg utfallet på 74%, vilket innebär att med hjälp av indikatorn kan önskade vedegenskaper anrikas. Vidare visar projektets resultat att gallringsskogar inte alls har de vedegenskaper som krävs för att få ett högt utfall av Lamina. Denna kunskap innebär att gallringar ska apteras på ett annat sätt än slutavverkningar och mot andra typer av slutprodukter. Indikatorn i sig har också förbättrats genom Mera Rätt Råvara 2.0. Ett problem med den befintliga skogliga indikatorn visade sig vara att skogsbeståndens skötselhistorik inte alltid var kända. I den nya indikatorn uteslöts skötselhistoriken som parameter och istället togs fler parametrar som beskriver det faktiska beståndet med i analysen. Den nya indikatorn visade sig också bli något bättre på att prediktera Laminavärdet. Projektet har varit så lyckat att resultaten används idag för att styra apteringen i våra avverkningar så att tillredningen i skogen bättre matchar de kundönskemål som sågverket har att ta hänsyn till.
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| 19. |
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| 20. |
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| 21. |
- Olofsson, Linus, et al.
(author)
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Customer adapted grading of Scots pine sawn timber - a multivariate method approach
- 2017
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In: 23rd International wood machining seminar. - Warsaw : Warsaw university of life sciences. - 9788394804602 ; , s. 360-361
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Conference paper (peer-reviewed)abstract
- At Scandinavian softwood sawmills, the most common system for grading of sawn timber in dry conditions is optical scanning equipment together with a rule-based automatic grading system (RBAG). The procedure to define new grading rules towards a customer with specified requirements is a time-consuming work for sawmills and is rarely implemented in a satisfactory way neither for the customer nor for the sawmill. An important consequence is that sawmills will, in general, not be able to deliver products that utilize the full potential of the quality distribution of the sawn timber produced at the sawmill. Their customers will get products with mismatch in desired and delivered quality grades. Thus, there is a need for a methodology that facilitates time and cost effective grading toward specific customers’ needs. The objective of the study was to further develop and validate a method that complements the RBAG by a holistic-subjective automatic grading (HSAG) approach - using multivariate regression models.In the study, 790 Scots pine boards with cross-section dimensions of 38×150 mm and length between 3.4 m and 5.6 m were manually graded according to the preferences of a large-volume customer, and also scanned and graded by an RBAG 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 than the grading by the RBAG system. The prediction of board grades based on multivariate models resulted in 84% of the boards graded correctly, according to the manual grading, while the corresponding number was 64% for the RBAG system. In a follow up grading test the accuracy of the two systems were 95% and 81%, respectively.
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| 22. |
- Olofsson, Linus, et al.
(author)
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Holistic-Subjective Automatic Grading of Sawn Timber : Sensitivity to Systematic Changes
- 2019
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In: IWMS-24 Proceedings. - : Oregon State University. ; , s. 157-164
-
Conference paper (other academic/artistic)abstract
- Holistic-subjective automatic grading of sawn timber by a partial least squares (PLS) regression model required training of the model. This study tests the sensitivity towards systematic changes of a specialized PLS model, trained on a selected type of material suitable for a specific paneling product, when used to grade sawn timber systematically different than the material it was trained on. A sawmills automatic scanning system used cameras to measure knot and bark features on 900 planks. Each plank was split into three boards, and each board was shaped into an indoor paneling product and manually graded as desirable or undesirable at a planing mill. The plank grade was decided as the majority of the board-grade outcome. The knot and bark measurements were used to create a large set of feature variables for each plank that was correlated to the plank’s grade by PLS regression. Of the 900 available planks, 434 planks sawn from top logs were used as a class-balanced specialistic training set, with half of the planks resulting in a majority of desirable boards. The regression model trained on the class-balanced specialistic training set was used to grade a test set of 282 planks, containing 64 planks that by manual classification of automatically captured images were determined to be sawn from butt logs and were systematically different from the training material. The PLS model’s grading accuracy of the planks sawn from top logs was 76%, compared to 70% for the plank sawn from butt logs. The grading outcome resulted in a higher proportion of both delivered planks from the sawmill and received desirable planks by the planing mill when grading planks from top logs as compared to planks from butt logs. The results indicated that a specialistic PLS model should not be used for a generalistic use-case.
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| 23. |
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| 24. |
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| 25. |
- Olofsson, Linus
(author)
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Machine Learning for Appearance Grading of Sawn Timber using Cameras and X-ray Computed Tomography
- 2021
-
Doctoral thesis (other academic/artistic)abstract
- This doctoral thesis deals with a new approach for the appearance grading of sawn timber adapted to the requirements of modern sawmilling industries and timber market situations. Appearance grading of sawn timber allows wood products to be made with a specific visual style due to wood features such as knots. Identifying and grading sawn timber by its visual style is a holistic-subjective task that is inherently suitable for humans. However, with the ever-increasing demand for a faster and more consistent grading operation, humans have been replaced by automatic systems during the past few decades. However, the human perception of the appearance of sawn timber is not something easily defined coherently and concisely for use in automatic systems, resulting in automatic systems struggling to perform appearance grading using conventional rule-based grading. As shown in this thesis, machine-learning methods can be used to teach an automatic system to perform holistic-subjective grading in a way that emulates manual grading while still performing the fast and consistent grading associated with automatic systems. This thesis introduced machine learning for product-adapted appearance grading of sawn timber and studied the use of machine learning to appearance grade sawn timber according to standardised quality grades, using an X-ray computed tomography (CT) scanner and a camera-based board scanner.In the studies presented in this thesis, measurement data from the CT scan-ner and the board scanner was used to create a set of variables only regarding knots. The variable sets and the grades of the sawn timber were modelled by projection to latent structures (PLS) models. The grade of the sawn timber was determined in three ways; firstly, manual grading according to standard-ised quality grades; secondly, called the product grade, the sawn timber was delivered to a wall-panelling customer, and the grade of the sawn timber was determined by the quality yield at the customer; and thirdly, called the image grade, images were extracted from the board scanner and used to estimate the quality yield of the wall-panelling customer manually. The grading in each scanning system was performed using a machine-learning method and a conventional rule-based approach, and their performances were compared.Seven data sets were collected in the studies presented in this thesis, each with a combination of variable sets from the scanners and quality grades as described above. In each study, one or more PLS models were trained to model the relationship between a variable set and a quality grade and used to predict the quality of the sawn timber. A PLS model predicts a score for each piece of sawn timber, and if that score passes a classification threshold, the model assigns a quality grade. This classification threshold could be tuned manually to introduce a bias in the model and thereby change the sorting outcome.When performing standardised appearance grading of dried sawn timber, both a PLS model and rule-based grading achieved about 80% grading accuracy, while a manual grader agreed to 95% with the PLS model and to 81% with the rule-based grading in a verification test. Furthermore, when performing customer-adapted grading of the standardised grades, a PLS model managed an 84% grading accuracy compared to 64% of the rule-based approach. These results show how a conventional rule-based ap-proach struggled with performing customer-adapted grading compared to a PLS model. When performing standardised grading, however, both meth-ods achieved similar grading accuracy, but only the grading performed by the PLS model could not be significantly distinguished from the targeted standardised grades.Using a PLS model to perform product-adapted grading of dried sawn tim-ber resulted in a grading accuracy of about 70%–80% for di˙erent scenarios. These gradings resulted in a quality yield, pass or fail, of about 80% for the wall-panelling customer. According to the customer, rule-based grad-ing did not yield impressive product-adapted results, and no metric was given. Furthermore, this thesis showed that the image grade was as useful as the product grade for training the PLS models, which greatly simplifies the logistical process of creating a data set for training a product-adapted machine-learning model. Had a traceability method been used to collect the data from the scanners automatically, the image grade would allow for completely software-based data collection, which is very much in line with the industry 4.0 concept.A CT scanner enables the appearance grading of virtual sawn timber in the 3D images of the scanned logs, which allows the logs to be sawn for maxi-mum value or quality yield. The CT scanner was made to perform a primary product-adapted grading using either a PLS model or a rule-based approach. In addition to this primary grading, the CT scanner and board scanner were programmed to perform a small secondary grading by limiting a small set of measurements that the CT scanner could not suÿciently account for. For example, large pith deviations were limited in the CT scanner, and rotten knots were forbidden by the board scanner, as these measurements were associated with a high risk of resulting in poor quality wall panels for the customer. With this setup, a dataset of 300 pieces of virtual sawn timber was studied. Using rule-based primary grading, the sawmill delivered about 200 pieces of sawn timber with a product yield of 77% for the customer, after the board scanner rejected 28 pieces (12%). Then, by controlling the classification threshold of a PLS model to make the primary grading very strict, meaning that the log was sawn to only yield very likely high-quality pieces of sawn timber, the sawmill could deliver 114 pieces of sawn timber with a product yield of 90%, after the board scanner rejected 9 pieces (7%). These results show that a PLS model achieved higher grading accuracy and higher quality yield than a rule-based approach. Furthermore, the classifica-tion threshold of the PLS model allows for easy and intuitive control over the sorting outcome, something that the rule-based approach does not support.This thesis showed that a PLS-based machine-learning model could be used to perform holistic-subjective appearance grading by both a CT scanner and a board scanner, where a rule-based approach struggled in all but the most familiar case of standardised grading. Once a framework for a machine-learning method such as PLS has been implemented, this thesis showed the ease of customising and fine-tuning the grading performance to be in line with customers needs. A customer or product adaptation could conceivably be initiated and finalised completely in software by automatically collecting the data using a traceability method, collecting the reference grades needed for training by grading images of sawn timber, and using the intuitive clas-sification threshold to fine-tune the sorting outcome.
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| 26. |
- Olofsson, Linus, et al.
(author)
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Multivariate product adapted grading of Scots pine sawn timber for an industrial customer, part 1 : Method development
- 2019
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In: Wood Material Science & Engineering. - : Taylor and Francis Ltd.. - 1748-0272 .- 1748-0280. ; 14:6, s. 428-436
-
Journal article (peer-reviewed)abstract
- 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 re-substitution 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.
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| 27. |
- Olofsson, Linus, 1992-, et al.
(author)
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Multivariate product adapted grading of Scots Pine sawn timber for an industrial customer, part 2 : Robustness to disturbances
- 2019
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In: Wood Material Science & Engineering. - : Taylor and Francis Ltd.. - 1748-0272 .- 1748-0280. ; 14:6, s. 420-427
-
Journal article (peer-reviewed)abstract
- 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.
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| 28. |
- Olofsson, Linus, et al.
(author)
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New possibilities with CT scanning in the forest value chain
- 2019
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In: Proceedings 21st International Nondestructive Testingand Evaluation of Wood Symposium. - : U.S. Department of Agriculture. ; , s. 569-576
-
Conference paper (other academic/artistic)abstract
- Industrial high-resolution X-ray computed tomography (CT) scanners have recently been installed at several sawmills worldwide for the description of roundwood interior features and external log shape. These CT scanners represent a technological advancement for sawmill businesses that open a way to higher volume and value yields and new production planning strategies. This paper will present an indicative study of innovative use of non-destructive CT log data in a Swedish softwood sawmill, linking high-quality information of the wood material along the wood-value chain. Sawn timber was observed throughout the sawmill process line, i.e. from the log yard through the sawmill process until grading after the timber was dried. Before sawing, the CT scanner scanned the logs and calculated knot measurements from the 3D CT log data of simulated value-optimized center yield. A corresponding set of knot measurements were later calculated from the camera-based grading of the dried timber. Only considering knots from the two sets of measurements, the sawn timber was automatically given a quality assessment based on CT data, by camera-based scanning data, and by manual visual grading for reference. Partial least squares regression was used to create prediction models by correlating the two sets of knot measurements with the automatically determined grade from the dry-sorting. The prediction models tested increased the grading consistency between the grading based on CT data of virtual planks and based on camera data of the same planks. Furthermore, a traceability algorithm was tested as a tool to generate large data sets for future studies.
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| 29. |
- Olofsson, Linus, et al.
(author)
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Phage display screening in low dielectric media
- 2008
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In: Journal of Molecular Recognition. - : Wiley. - 0952-3499 .- 1099-1352. ; 21:5, s. 330-337
-
Journal article (peer-reviewed)abstract
- Here we report the first application of phage display screening in low dielectric media. Two series of phage clones with affinity for α-chymotrypsin (CT) were selected from a Ph.D.TM-C7C library, using either a buffer or acetonitrile in buffer (50%, v/v). The affinity of lysates, individual clones or selected cyclic peptides for the enzyme was studied by examining their influence on CT activity. Peptides displayed on phage selected in buffer provided significant protection from enzyme autolysis resulting in marked increase in CT activity (>100%). Phage selected in ACN provided some, albeit weak, protection from the detrimental influence on CT from ACN. In conclusion, the results demonstrate the potential for the application of phage display screening protocols to targets in media of low dielectricity.
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| 30. |
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| 31. |
- Olofsson, Linus, et al.
(author)
-
Product-adapted grading of Scots pine sawn timber by an industrial CT-scanner using a visually-trained machine-learning method
- 2021
-
In: Wood Material Science & Engineering. - : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 16:4, s. 279-286
-
Journal article (peer-reviewed)abstract
- Computed tomography (CT) scanning of logs makes appearance-grading virtual sawn timber possible before the log is sawn. A CT-scanner can measure the knot structure inside a scanned log, inferring how to saw the log. The knot structure of virtual sawn timber was graded as being suitable or not for a specific product by the existing rule-based approach and used to create a set of descriptive statistical variables used by two machine learning models. The PLS models were trained on two quality references; the quality grade of the finished product or the image-grade based on images of the sawn timber, extracted from the dry-sorting station's automatic grading system and graded by two experienced researchers. The results show that the two PLS models perform equally well when sorting sawn timber to the customer, indicating that the quality references are equally useful for training a PLS model. The PLS models both delivered 93% of the dried sawn timber to the customer, leaving very little sawn timber with customer-specific properties at the sawmill, of which 89% and 90% of the delivered sawn timber passed the intended product's quality demands. The rule-based approach delivered 85% dried sawn timber with a 73% pass rate.
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| 32. |
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| 33. |
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| 34. |
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| 35. |
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| 36. |
- Olofsson, Linus, et al.
(author)
-
The effect of class-balance and class-overlap in the training set for multivariate and product-adapted grading of Scots pine sawn timber
- 2021
-
In: Wood Material Science & Engineering. - London : Taylor & Francis Group. - 1748-0272 .- 1748-0280. ; 16:1, s. 58-63
-
Journal article (peer-reviewed)abstract
- Using multivariate partial least squares regression (PLS) to perform visual quality grading of sawn timber requires a training set with known quality grades for the training of a grading model. This study evaluated the grading accuracy of an independent test set of sawn timber when changing the aspects of class-balance and class-overlap of the training set consisting of 251 planks. The study also compared two ways of expressing the reference-grade of the training set; by grading images picturing the planks, and by grading the product produced from the planks. Two grading models were trained using each reference-grade to establish a baseline for comparison. Both models achieved a 76% grading accuracy of the test set, indicating that both reference-grades can be used to train comparable models. To study the class-balance and class-overlap aspects of the training set, 25% of the training set was removed in two training scenarios. The models trained on class-balanced data indicated that class-imbalance of the training set was not a problem. The models trained on data with less class-overlap using the product-grade reference suffered a 4%-points grading accuracy loss due to the smaller training set, while the model trained using the image-grade reference retained its grading accuracy.
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| 37. |
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| 38. |
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| 39. |
- Olofsson, Thomas, et al.
(author)
-
Kravhantering, produkt- och projektutveckling av industriella byggkoncept
- 2012
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Reports (other academic/artistic)abstract
- I ett industriellt byggande måste krav och önskemål hanteras i två utvecklingsfaser dels i den normala byggprocessen, s.k. projektutvecklingsfas, dels när det industriella konceptet utvecklas i en separat produktutvecklingsprocess, som är åtskild från byggprocessen. När produktutvecklingsfasen är genomförd, ska den på något sätt paketeras, lanseras, tillämpas och förvaltas. Plattformar och produktfamiljer är begrepp som används för att beskriva utvecklingen av strategier för s.k. "mass customization" i den fasta industrin, d v s sättet att med bibehållen skalfördel i mass-produktionssystem kunna anpassa produkten efter kundens önskemål. Det innebär att ägaren av ett byggkoncept skall utveckla dessa plattformar för projektering, produktion och försörjningskedjor som sedan används i projektutvecklingen av konceptet till färdig byggnad. Alla koncept måste pro-jektutvecklas till viss del, d v s anpassas till platsen. Hur stor del som konceptet specificeras i förväg, d v s i teknik och processutvecklingsskedet styr också i hög grad hur byggprocessen behöver förändras. Dagens utvecklade byggsystem har olika flexibilitet, förtillverkningsgrad och integration av leveran-törskedjor. Vilket innebär att möjlighet till kundanpassning varierar. Det är också viktigt att komma in tidigt i beställarens byggprocess för att kunna erbjuda alternativ som passar. Förutom krav som to-talentreprenad, kan lokala detaljplaner, illustrationsplaner och skisser innefatta krav som kullkastar användande av ett utvecklat koncept. Industriella byggare måste därför utveckla mer geometriskt flexibla byggkoncept än idag så att de bättre kan uppfylla framtida detaljplaners bestämmelser och intentioner. Resultaten från kravhanteringen visar att kravbild och kravnivåer är fragmenterade och olika för olika kravställare. En övervägande del av kraven ska beaktas i projekteringsskedet. Koncept som har hög grad av standardisering så måste byggherren tydligt tjäna tid, pengar och kvalitet på att anstränga sig för att anpassa sitt projekt till plattformen. Kravhantering ersätts i princip med en säljprocess där byggherren/kunden har att ta ställning till ett antal val. Görs oförutsedda avsteg från ett sådant kon-cept förlorar man snabbt vitsen med industrialiseringen. I projektutvecklingen, d v s när konceptet skall anpassas till kund och plats, kan prestanda¬analyser förenklas avsevärt. En stor del av konceptets egenskaper eller indata kommer att vara gemensamt och på förhand känt, d v s endast de egenskaperna som varieras (påverkas av kundanpassningen) behöver definieras. I fallstudien demonstrerades detta med en utvecklad applikation för energianalyser i ett projektutvecklingsskede. Fallstudien med avseende på konceptutveckling av en betongvägg visar att hög energiprestanda och fuktprestanda ej behöver stå i motsats till varandra. Den valda lösningen av de konceptutvecklade betongväggen gav knappt märkbar försämring av fuktprestanda samtidigt som energiprestandan förbättrades väsentligt. Vidare så kunde anslutningen förbättras utan att påverka det arkitektoniska uttrycket. En observation som gjordes i detta arbete var att modularisering med avseende på funktion krävdes. Metodiken som utvecklades i fallstudien lämpar sig mycket väl i ett industriellt byggande baserat på tekniska plattformar där en stor del av de tekniska lösningarna, komponenter och basmoduler är definierade. Vi tror att industrialiserat byggande har en framtid men att det kommer under en lång tid att ske i avgränsade nischer medans de stora förändringarna kommer att ske när dagens platsbyggda flerbo-stadshus övergår till i att allt högre grad baseras på byggsystem och plattformstänkande. En intressant utveckling blir när standardisering av komponenter och processer integreras i plattformar där effektivitetsvinster kan göras i alla led i byggprocessen från projektering och inköp till produktion och montering på plats.
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| 40. |
- Rebeggiani, Sabina, et al.
(author)
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Towards In-Line Measurements of Sawn Wood Surfaces
- 2024
-
In: Sustainable Production through Advanced Manufacturing, Intelligent Automation and Work Integrated Learning. - : IOS Press. ; , s. 15-26
-
Conference paper (peer-reviewed)abstract
- Metrology and characterisation of products' functional surfaces are of key importance in smart and sustainable manufacturing. By proper measures of resulting topography and dimension at the micro-cm level, higher process control can be achieved, leading to more efficient production with products closer to defined targets. Commercial surface metrology systems for lab- and in/on-line applications have increased in the last decades, but the wood sector has not yet benefited from this development. A better understanding of sawn wood topography combined with smart online metrology systems is expected to lead to a substantial reduction of waste in sawmill production, both by transforming waste pieces and sideboards into engineered wood products and by optimising the sawing process (e.g. by using thinner saw blades and reduced tolerances). It would also open new design possibilities and challenge the construction sector to replace today’s materials with renewable raw materials. Additionally, sawmills will be less dependent on incoming timber dimensions. This study is the first step towards a better understanding of sawn wood topography and how relevant surface features can be detected and analysed to enable the next generation of functional wood surfaces for various applications. By identifying the measuring instrument’s capability to capture surface topographical features of sawn wood, this paper discusses the requirements for efficient measurement techniques. It opens for future implementation of machine learning algorithms to in-line monitor and control the machining process. All tested metrology techniques showed promising results. To capture machining marks, the instrumentation needs to have lateral resolutions on the um level and a measurement area covering some cm; thus, the laser scanning system seemed to be a good compromise.
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| 41. |
- Rebeggiani, Sabina, 1980-, et al.
(author)
-
Towards In-Line Measurements of Sawn Wood Surfaces
- 2024
-
In: Sustainable Production through Advanced Manufacturing, Intelligent Automation and Work Integrated Learning. - Amsterdam : IOS Press. - 9781643685106 ; , s. 15-26
-
Conference paper (peer-reviewed)abstract
- Metrology and characterisation of products' functional surfaces are of key importance in smart and sustainable manufacturing. By proper measures of resulting topography and dimension at the micro-cm level, higher process control can be achieved, leading to more efficient production with products closer to defined targets. Commercial surface metrology systems for lab- and in/on-line applications have increased in the last decades, but the wood sector has not yet benefited from this development. A better understanding of sawn wood topography combined with smart online metrology systems is expected to lead to a substantial reduction of waste in sawmill production, both by transforming waste pieces and sideboards into engineered wood products and by optimising the sawing process (e.g. by using thinner saw blades and reduced tolerances). It would also open new design possibilities and challenge the construction sector to replace today’s materials with renewable raw materials. Additionally, sawmills will be less dependent on incoming timber dimensions. This study is the first step towards a better understanding of sawn wood topography and how relevant surface features can be detected and analysed to enable the next generation of functional wood surfaces for various applications. By identifying the measuring instrument’s capability to capture surface topographical features of sawn wood, this paper discusses the requirements for efficient measurement techniques. It opens for future implementation of machine learning algorithms to in-line monitor and control the machining process. All tested metrology techniques showed promising results. To capture machining marks, the instrumentation needs to have lateral resolutions on the um level and a measurement area covering some cm; thus, the laser scanning system seemed to be a good compromise. © 2024 The Authors.
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