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  • 1.
    Ahmed, Faisal
    et al.
    Department of Computer Science and Engineering, Premier University, Chattogram, Bangladesh.
    Naim Uddin Rahi, Mohammad
    Department of Computer Science and Engineering, Premier University, Chattogram, Bangladesh.
    Uddin, Raihan
    Department of Computer Science and Engineering, Premier University, Chattogram, Bangladesh.
    Sen, Anik
    Department of Computer Science and Engineering, Premier University, Chattogram, Bangladesh.
    Shahadat Hossain, Mohammad
    University of Chittagong, Chattogram, Bangladesh.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Machine Learning-Based Tomato Leaf Disease Diagnosis Using Radiomics Features2023In: Proceedings of the Fourth International Conference on Trends in Computational and Cognitive Engineering - TCCE 2022 / [ed] M. Shamim Kaiser; Sajjad Waheed; Anirban Bandyopadhyay; Mufti Mahmud; Kanad Ray, Springer Science and Business Media Deutschland GmbH , 2023, Vol. 1, p. 25-35Conference paper (Refereed)
    Abstract [en]

    Tomato leaves can be infected with various infectious viruses and fungal diseases that drastically reduce tomato production and incur a great economic loss. Therefore, tomato leaf disease detection and identification are crucial for maintaining the global demand for tomatoes for a large population. This paper proposes a machine learning-based technique to identify diseases on tomato leaves and classify them into three diseases (Septoria, Yellow Curl Leaf, and Late Blight) and one healthy class. The proposed method extracts radiomics-based features from tomato leaf images and identifies the disease with a gradient boosting classifier. The dataset used in this study consists of 4000 tomato leaf disease images collected from the Plant Village dataset. The experimental results demonstrate the effectiveness and applicability of our proposed method for tomato leaf disease detection and classification.

  • 2.
    Alenius, Christoffer
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Dynamic simulation and techno-economicevaluation of a seasonally insulated hybridgreenhouse concept for subarctic climates2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Swedish authority for social protection and preparedness, MSB, believes that the self-sufficiency of the country must be strengthened in order to be prepared for a crisis. Presently, Sweden is only 50% self-sufficientwhich is very low compared to its neighboring countries; and it is worse the further north you go. One solution could be to increase the production of food, for example vegetables, but the number of greenhouse operations in Sweden are already dwindling due to the inhospitable climate, which makes it expensive to keep up all-year cultivations. Norrbotten, the northernmost part of Sweden, has the highest heat demand for greenhouses in the country. One option could be to set up operation in heavily insulated buildings and rely on artificial lighting, in so called plant factories. Though, these are expensive, electricity intensive and have generally lower yields.

    This report will cover the development, validation, and performance of a dynamic model of a new greenhouse concept, developed for subarctic climates. The greenhouse is meant to utilize the strengths of both glass houses and plant factories to optimize the profits for a year-round operation. This, to find an alternative solution to the self-sufficiency problem in the winter. In addition to this, the optimal glaze for the climate shell had to be determined and what type of lighting technology would be the most viable. The hybrid greenhouse is a gableroof greenhouse with insulated north, west and east walls designed for microgreen cultivation, Lactuca Sativa. The interesting part of the greenhouse is that it has a retractable insulation cover, of mineral wool, inside of the climate shell. This was meant to heavily insulate the greenhouse during the winter seasons, though it would not let any sunlight in. This meant that the hybrid greenhouse must rely on artificial lighting in the winter but will get a reduced heating demand. When the outdoor temperature rises and the sun becomes more visible,the cover can be retracted to utilize sunlight for heating and photosynthesis. The cost between heating and electricity usage and the profits from the amount of yield will therefore vary depending on how long the coveris opened or closed and an optimal cost solution should be found somewhere within that variation. The model was created using Simulink version 10.6, which could simulate the heat demand, the humidity level, CO2-concentration, and the yield of the greenhouse.

    The models heat demand and yield was validated againsta greenhouse in Nikkala, Sweden, owned by Norrskenstomater. The model produced a standard deviation of 24.6 MWh over three months but it overestimated the yearly yield of Norrskenstomater with about 40%. To make the sure the hybrid greenhouse performed effectively, the amount of leakage must be minimized, as this has a significant impact on the heat demand. The hybrid greenhouse needs lighting alternatives with substantial active cooling (90% of the lamps input power), such as light emitting diodes. High pressure sodium lamps produce too much heat and can not be used at all. For yearly simulations, the cover was set to close for certain amounts of months during the year. The highest yearly profit, highest net present value (4.8 MSEK) and lowest payback time (3.5 years) could be achieved if the cover were closed between October and March. The best glazing material in terms of economic performance was 4 mm glass followed by 16 mm plastic panels in acrylic. The hybrid greenhouse could even outperform a greenhouse that did not cultivate during the winter. The hybrid greenhouse seems to get rid of the negative impacts of winter cultivation and is therefore considereda viable alternative as a cultivation system for subarctic climates. 

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  • 3.
    Amiandamhen, Stephen O.
    et al.
    Department of Forestry and Wood Technology, Faculty of Technology, Linnaeus University, Lückligs Plats 1, Växjö 35195 Sweden.
    Kumar, Anuj
    Natural Resources Institute Finland (Luke), Production Systems, Tietotie 2, Espoo 02150 Finland.
    Adamopoulos, Stergios
    Department of Forestry and Wood Technology, Faculty of Technology, Linnaeus University, Lückligs Plats 1, Växjö 35195 Sweden.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Faculty of Forestry and Wood Sciences, Czech University of Life sciences Prague, Kamýcká 129, 165 21 Praha 6 – Suchdol, Czech Republic.
    Nilsson, Bengt
    Department of Forestry and Wood Technology, Faculty of Technology, Linnaeus University, Lückligs Plats 1, Växjö 35195 Sweden.
    Bioenergy production and utilization in different sectors in Sweden: A state of the art review2020In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 15, no 4, p. 9834-9857Article, review/survey (Refereed)
    Abstract [en]

    In the continual desire to reduce the environmental footprints of human activities, research efforts to provide cleaner energy is increasingly becoming vital. The effect of climate change on present and future existence, sustainable processes, and utilizations of renewable resources have been active topics within international discourse. In order to reduce the greenhouse gases emissions from traditional materials and processes, there has been a shift to more environmental friendly alternatives. The conversion of biomass to bioenergy, including biofuels has been considered to contribute to the future of climate change mitigation, although there are concerns about carbon balance from forest utilization. Bioenergy accounts for more than one-third of all energy used in Sweden and biomass has provided about 60% of the fuel for district heating. Apart from heat and electricity supply, the transport sector, with about 30% of global energy use, has a significant role in a sustainable bioenergy system. This review presents the state of the art in the Swedish bioenergy sector based on literature and Swedish Energy Agency’s current statistics. The review also discusses the overall bioenergy production and utilization in different sectors in Sweden. The current potential, challenges, and environmental considerations of bioenergy production are also discussed.

  • 4.
    Ammara, Sumbal
    et al.
    Environmental Science Program, Centre for Interdisciplinary Research in Basic Sciences, International Islamic University, Islamabad, 44000, Pakistan.
    Rafiq, Muhammad Tariq
    Environmental Science Program, Centre for Interdisciplinary Research in Basic Sciences, International Islamic University, Islamabad, 44000, Pakistan.
    Aziz, Rukhsanda
    Environmental Science Program, Centre for Interdisciplinary Research in Basic Sciences, International Islamic University, Islamabad, 44000, Pakistan.
    Feng, Ying
    Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.
    Mehmood, Sultan
    Horticultural Research Institute, National Agricultural Research Centre, Islamabad, 44000, Pakistan.
    Taneez, Mehwish
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Suhaib, Muhammad
    Land Resources Research Institute, National Agricultural Research Centre, Islamabad, 44000, Pakistan.
    Asif, Fatima
    Environmental Science Program, Centre for Interdisciplinary Research in Basic Sciences, International Islamic University, Islamabad, 44000, Pakistan.
    Nickel uptake in leafy greens from contaminated soil: an investigation into phytoavailability and health risk assessment using in vitro digestion model2024In: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 196, no 2, article id 171Article in journal (Refereed)
  • 5.
    Andersson, Martina
    et al.
    Department of Political Science, Umeå University, SE90187 Umeå, Sweden.
    Bostedt, Göran
    Luleå University of Technology, Department of Social Sciences, Technology and Arts, Social Sciences. Department of Forest Economics, SLU, Umeå, Sweden.
    Sandström, Camilla
    Department of Political Science, Umeå University, SE90187 Umeå, Sweden.
    The role of Swedish forests in climate change mitigation - A frame analysis of conflicting interests2022In: Forest Policy and Economics, ISSN 1389-9341, E-ISSN 1872-7050, Vol. 144, article id 102842Article in journal (Refereed)
    Abstract [en]

    Forests are assumed to play a significant role in relation to climate change mitigation. However, previous studies show that actor groups’ perspectives vary regarding how to best utilize forests. This paper focuses on exploring frames in recent Swedish forest- and climate politics and to what extent they may form the basis for conflict resolution or contribute to perpetuate conflicts among actors. The analysis of recent forest- and climate policies, and actor groups’ positioning on the issues, builds upon the pathways to sustainability approach in combination with frame analysis. The results showed that ideas based on “Ecological Modernisation” dominated within the forest-climate nexus, but also a clear presence of alternative frames promoting “Sustainable Development”. As a result, conflicting frames were identified within the policies on how to reach policy targets - stressing both the importance of consensus and neutral dialogue with actors, while concurrently prioritizing an economic perspective.

  • 6.
    Arnberg, John
    Luleå University of Technology, Department of Social Sciences, Technology and Arts.
    Det gröna hemmet: Biofil design för hållbar odling i hemmet2023Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    We are moving towards a future where an increasingly larger portion of the world’s population lives in urban areas, which entails a number of challenges that will need to be addressed. By the year 2050, it is expected that nearly 70% of the population will reside in urban areas, compared to 30% in 1950. This increase means that green spaces will be replaced by housing, leading to smaller-sized homes and rising prices. At the same time, the negative effects of not being surrounded by plants and nature are becoming more significant and evident.This project in Technical Design at Luleå University of Technology aims to explore the possibilities of mitigating these negative effects by creating sustainable opportunities for individuals to cultivate plants at home. By examining the needs of the target audience and employing a user-centered design process, a variety of creative design methods have been utilized to explore solutions and possibilities. Through an iterative process, a range of different solutions have been developed and evaluated by users.This has resulted in a concept that allows for home cultivation using vertical hydroponic farming,

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  • 7.
    Bachtiar, Erik Valetine
    et al.
    Fraunhofer-Institut für Holzforschung, Wilhelm-Klauditz-Institut WKI, Braunschweig, Germany.
    Niemz, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. ETH Zürich, Institute for Building Materials, Zürich, Switzerland; Department of Forestry and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Department of Forestry and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Properties of adhesive films used in cultural assets2022In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 17, no 2, p. 147-150Article in journal (Refereed)
    Abstract [en]

    The hygroscopic nature of wood leads to large moisture fluctuations in the material that may influence the mechanical performance of glued wood products. Adhesives based on bone, fish and hide have a long tradition for the gluing of wood and can be found in wooden structures in our cultural heritage. In this study, selected sorptive and mechanical properties of animal adhesives have been compiled and compared to those of synthetic polyurethane adhesives. Bone, fish and hide adhesives show a high moisture uptake at high relative humidity, which confirms the low moisture resistance of such adhesives. The modulus of elasticity and ultimate tensile strength of the films based on animal adhesives are considerably reduced when the moisture content is increased.

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  • 8.
    Bandura, Iryna
    et al.
    Tavria State Agrotechnological University, Department of technology of processi ng and storage of agricultural products.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Assessment of Raw Plant material and Substrate for Efficient production of Oyster Mushrooms (Pleurotusostreatus (Jacq.) P. Kumm.)2016In: Ochrana drevín a dreva 2016: zborník recenzovaných vedeckých prác a abstraktov / [ed] Pavol Hlaváč , Zuzana Vidholdová, Zvolen: Technická univerzita vo Zvolene , 2016, p. 27-33Conference paper (Refereed)
    Abstract [en]

    Microbial analysis of raw materials and substrate during all phases of thermal processing revealed the most efficient methods for industrial mushroom cultivation. The aerobic fermentation in the upper layer is preferable if using long term stored material. The oyster mushroom strain HK-35 was used for testing. An increase in biological efficiency with 37% was found for aerobic fermentation in comparison with stream processing. From evaluation of temperature influence during pasteurization phase, the biological efficiency increased with 11% for tested temperature treatment at 74±3°С in comparison to the standard at 63±3°С.

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    oyster
  • 9.
    Bandura, Iryna
    et al.
    Tavria State Agrotechnological University .
    Myronycheva, Olena
    Tavria State Agrotechnological University .
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Anike, F.N.
    North Carolina A&T State University, Greensboro.
    Isikhuemhen, O.S.
    North Carolina A&T State University, Greensboro.
    Pretreatment of wheat straw and solid state fermentation improves yield and biological efficiency in Pleurotus ostreatus Jacq) P. Kumm. mushroom production2017In: Advances in medicinal mushroom science: Building bridges between Western and Eastern medicine : th International medicinal mushrooms conference : book of abstracts / [ed] Maria Letizia Gardano, Giuseppe Venturella, Palermo, Italy: University of Palermo , 2017, p. 41-43Conference paper (Refereed)
    Abstract [en]

    The pretreatment method for generating substrate for large scale production of oyster mushroom is critical for determining high yield and biological efficiency (BE). The aim of this study was to develop an optimal storage and pretreatment procedure for substrate used in oyster mushroom production. The effect of wheat straw substrate storage (outdoor- open air versus indoor- closed barn) and pretreatment (steam (SP) and hot water (HWP) pasteurization and solid state fermentation (SSF)) on substrate microbiological quality, mushroom yield/BE were investigated during the cultivation of Pleurotus ostreatus strain HK-35. The influence of temperatures used during solid state fermentation on BE was also investigated. There were significant changes among the parameters measured (moisture, total nitrogen, ash content, C/N ratio and total microbial count (CFU) between indoor and outdoor storage. The indoor storage gave higher values. With outdoor storage, CFU showed about 800 times increase. Among the substrate treatment methodstested (SP-control, HWP and SSF), SSF gave consistently higher fruit body yield and BE which ranged from 77-86% compared to the control which ranged from 40-53%. Also SSF conducted at higher temperature (74°C) gave higher BE of 81.2% compared to one conducted at lower temperature (63°C), which gave BE of 69.4%. We consider these findings to be useful in further studies on the redesign oF industrial production systems, which can make oyster mushroom production more profitable in Ukraine and beyond.

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  • 10.
    Bekhta, Pavlo
    et al.
    Department of Wood-Based Composites, Cellulose and Paper, Ukrainian National Forestry University, Lviv, 79057, Ukraine.
    Sedliačik, Ján
    Department of Furniture and Wood Products, Technical University in Zvolen, 960 53, Zvolen, Slovakia.
    Jones, Dennis
    SP Technical Research Institute of Sweden, Drottning Kristinas väg 67, 114 86, Stockholm, Sweden.
    Effect of short-term thermomechanical densification of wood veneers on the properties of birch plywood2018In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 76, no 2, p. 549-562Article in journal (Refereed)
  • 11.
    Beregniak, Evgeniy
    et al.
    Department of Agrosphere Ecology and Environmental Control, National University of Life and Environmental Sciences of Ukraine, Geroiv Oboroni Str. 15, 03041 Kyiv, Ukraine.
    Beregniak, Mykhailo
    Department of Soil Science and Soil Conservation by Professor M.K. Shykula, National University of Life and Environmental Sciences of Ukraine, Geroiv Oboroni Str. 15, 03041 Kyiv, Ukraine.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Balabak, Alla
    Department of Ecology and Life Safety, Uman National University of Horticulture, 20300, Uman, Institutska Str., 1, Ukraine.
    Belava, Victoriia
    ESC, Institute of Biology and Medicine, Department Biology Plants, Taras Shevchenko National University of Kyiv, Volodymyrska Str. 64/13, Kyiv 01601, Ukraine.
    Boroday, Vira
    Department of Ecobiotechnology and Biodiversity, National University of Life and Environmental Sciences of Ukraine, Geroiv Oboroni Str. 15, 03041 Kyiv, Ukraine.
    Nedilska, Uliana
    Department of Ecology and General Biological Subjects, Higher Educational Institution “Podillia State University”, Shevchenko 13, Kamenets-Podolsky, 31302, Ukraine.
    Hudyma, Volodymyr
    Laboratory of Silvology and Silviculture, Ukrainian Research Institute of Mountain Forestry named after P.S. Pasternak Hrushevsky str.31 76004 Ivano-Frankivsk Ukraine.
    Kucher, Larisa
    Department of Soil Science and Soil Conservation by Professor M.K. Shykula, National University of Life and Environmental Sciences of Ukraine, Geroiv Oboroni Str. 15, 03041 Kyiv, Ukraine.
    Voitsekhivskyi, Volodymyr
    Department Technology of Storage, Processing and Standardizations of Planting Products by Professor B.V. Lesik, National University of Life and Environmental Sciences of Ukraine, Geroiv Oboroni Str. 15, 03041 Kyiv, Ukraine.
    Ecological Analysis of the Current State of Forest Resources in Forest Steppe of Ukraine2023In: Journal of Ecological Engineering, E-ISSN 2299-8993, Vol. 24, no 1, p. 87-96Article in journal (Refereed)
    Abstract [en]

    Forests perform essential ecological functions - water protection, sanitation, health, recreation, and aesthetics. The research aimed to substantiate the ecological and economic importance of forest resources in the Kyiv region and analyse their rational use and protection. The article shows that the Kyiv region belongs to the regions with an average level of forest cover – 592.8 thousand hectares or 22.2%. The level of forest cover is uneven in the area of the Kyiv Forest zone. It is 44%, and in the area of the Forest-Steppe, it is much lower and decreases from north to south. The use of forest resources in the Kyiv region in 2019 amounted to harvesting liquid wood of 999.5 thousand m2, and deforestation was carried out on 75.5 thousand hectares. The region's volume of forestry works and services amounted to 8,9 million dollars, and the wood stock makes 90805,9 thousand m2. Emphasis is placed on the importance of protecting the Red Book species of plants and fungi that grow in the forests of the Kyiv region. Examples of harmful economic activity in the areas belonging to the nature reserve fund and large-scale fires in April 2020, which covered more than 3.5 thousand hectares of forests in the region and caused damage to forest fauna and flora. The studied region's positive environmental and economic factors have been admitted by planting trees on an area of 2151 hectares and sowing seeds of forest species on an area of 67 hectares in 2020.

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  • 12.
    Berg, Sven
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Turesson, Jonas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ekevad, Mats
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Huber, Johannes Albert Josef
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Finite element analysis of bending stiffness for cross-laminated timber with varying board width2019In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 14, no 6, p. 392-403Article in journal (Refereed)
    Abstract [en]

    Cross laminated timber (CLT) is a wood panelling building system that is used in construction, e.g. for floors, walls and beams. Because of the increased use of CLT, it is important to have accurate simulation models. CLT systems are simulated with one-dimensional and two-dimensional (2D) methods because they are fast and deliver practical results. However, because non-edge-glued panels cannot be modelled under 2D, these results may differ from more accurate calculations in three dimensions (3D). In this investigation, CLT panels with different width-to-thickness ratios for the boards have been simulated using the finite element method. The size of the CLT-panels was 3.0 m × 3.9 m and they had three and five laminate layers oriented 0°–90°–0° and 0°–90°–0°–90°–0°. The thicknesses of the boards were 33.33, 40.0, and 46.5 mm. The CLT panel deformation was compared by using a distributed out-of-plane load. Results showed that panels with narrow boards were less stiff than wide boards for the four-sided support setup. The results also showed that 2D models underestimate the displacement when compared to 3D models. By adjusting the stiffness factor k88, the 2D model displacement became more comparable to the 3D model.

  • 13.
    Bernaczyk, Arkadiusz
    et al.
    Jowat SE, Detmold, 32758, Germany.
    Wagenführ, André
    Institute of Natural Materials Technology, Technische Universität Dresden, Dresden, 01062, Germany.
    Terfloth, Christian
    Jowat SE, Detmold, 32758, Germany.
    Lincke, Jörg
    Jowat SE, Detmold, 32758, Germany.
    Krystofiak, Tomasz
    Department of Wood Science and Thermal Techniques, Poznań University of Life Sciences, Poznan, 60-627, Poland.
    Niemz, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Institute for Building Materials, ETH Zurich, 971 87 Luleå, Sweden.
    Investigations into the Influence of Temperature on the Tensile Shear Strength of Various Adhesives2023In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 16, no 18, article id 6173Article in journal (Refereed)
    Abstract [en]

    The temperature resistance of glued timber, which is crucial for glued wood construction, represents a significant assessment criterion. To gain insights into this aspect, this study utilized methods such as a shear strength test in accordance with EN 302-1:2013-06 under thermal loading (from 20 °C to 200 °C), and Differential Scanning Calorimetry (DSC) to determine the glass transition temperature (Tg). An increase in thermal load resulted in a decrease in shear strength and an increase in wood breakage. A hierarchy of adhesive groups was established based on strength performance and wood failure percentage (WFP) at 200 °C. Thermoset adhesives (MF: Melamine Formaldehyde, PRF: Phenol Resorcinol Formaldehyde) led the ranking, followed by elastomer adhesives (1C-PUR: One-Component Polyurethane, EPI: Emulsion Polymer Isocyanate), with thermoplastic adhesive (PVAc: Polyvinyl Acetate) last. Thermoset adhesives further cured under heat. PUR adhesives exhibited higher strength performance at 150 °C and lower temperatures.

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  • 14.
    Bernaczyk, Arkadiusz
    et al.
    Jowat SE, 32758 Detmold, Germany.
    Wagenführ, André
    Institute of Natural Materials Technology, Technische Universität Dresden, 01062 Dresden, Germany.
    Zboray, Robert
    Center for X-ray Analytics, Empa—Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
    Flisch, Alexander
    Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany.
    Lüthi, Thomas
    Center for X-ray Analytics, Empa—Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
    Vetter, Birgit
    Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany.
    Rentsch, Mario
    Institute of Materials Science, Technische Universität Dresden, 01062 Dresden, Germany.
    Terfloth, Christian
    Jowat SE, 32758 Detmold, Germany.
    Lincke, Jörg
    Jowat SE, 32758 Detmold, Germany.
    Krystofiak, Tomasz
    Department of Wood Science and Thermal Techniques, Poznań University of Life Sciences, 60-627 Poznan, Poland.
    Niemz, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Investigations on the Characterization of Various Adhesive Joints by Means of Nanoindentation and Computer Tomography2022In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, no 23, p. 8604-8604Article in journal (Refereed)
    Abstract [en]

    The mechanical properties of cured wood adhesive films were tested in a dry state by means of nanoindentation. These studies have found that the application of adhesives have an effect on the accuracy of the hardness and elastic modulus determination. The highest values of hardness among the tested adhesives at 20 °C have condensation resins: MF (0.64 GPa) and RPF (0.52 GPa). Then the decreasing EPI (0.43 GPa), PUR (0.23 GPa) and PVAc (0.14 GPa) adhesives. The values of the elastic modulus look a little bit different. The highest values among the tested adhesives at 20 °C have EPI (11.97 GPa), followed by MF (10.54 GPa), RPF (7.98 GPa), PVAc (4.71 GPa) and PUR (3.37 GPa). X-ray micro-computed tomography was used to evaluate the adhesive joint by the determination of the voids. It has been proven that this value depends on the type of adhesive, glue quantity and reactivity. The highest values of the void ratio achieve the PUR (17.26%) adhesives, then PVAc (13.97%), RRF (6.88%), MF (1.78%) and EPI (0.03%). The ratio of the gaps increases with the higher joint thickness. A too high proportion of voids may weaken the adhesive joint.

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  • 15.
    Blomqvist, Lars
    et al.
    Linnӕus University, Department of Building Technology, Växjö, Sweden. RISE, Research Institute of Sweden.
    Berg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Department of Wood Processing and Biomaterials, Czech University of Life Sciences Prague, Prague, Czech Republic.
    Distortion in laminated veneer products exposed to relative-humidity variations: Experimental studies and finite-element modelling2019In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 2, p. 3768-3779Article in journal (Refereed)
    Abstract [en]

    A shortcoming of the laminated bending process is that the product may become distorted after moulding. This study focused on the influence of fibre orientation deviation for individual veneers on the distortion of a moulded shell. The distortion of 90 cross-laminated shells of the same geometrical shape, consisting of seven peeled birch veneers, were studied under relative humidity variation. All the veneers were straight-grained in the longitudinal-tangential plane, but to simulate a deviation in fibre orientation, some of the individual veneers were oriented at an angle of 7° relative to the main orientation of the other veneers in the laminate. A finite element model (FEM) was applied to study the possibility of predicting the results of a practical experiment. The study confirms the well-known fact that deviation in fibre orientation influences shape stability. The results also show how the placement of the abnormal veneer influences the degree of distortion. From this basic knowledge, some improvements in the industrial production were suggested. However, the FE model significantly underestimated the results, according to the empirical experiment, and it did not show full coherence. The survey shows the complexity of modelling the behaviour of laminated veneer products under changing climate conditions and that there is a great need to improve the material and process data to achieve accurate simulations. Examples of such parameters that may lead to distortion are density, annual ring orientation in the cross section of the veneer, the orientation of the loose and tight sides of the veneer, and parameters related to the design of the moulding tool.

  • 16.
    Borko, Domen
    et al.
    Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
    Scharf, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lin, Chia-Feng
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Humar, Miha
    Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
    The potential of citric acid and glucose enhancing the reaction of wood with bicine and tricine2024In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280Article in journal (Refereed)
    Abstract [en]

    To improve the resistance of wood to biological decay the Maillard reaction between introduced amines and wood cell-wall polymers can be utilised. However, initial studies in wood modification showed almost complete leaching of bicine and tricine from treated wood and the loss of beneficial effects. The objective of this study was to assess whether possible reactions of bicine or tricine with wood could be further enhanced and reaction products stabilised through the addition of glucose and/or citric acid. Thus, Scots pine sapwood specimens were impregnated with tricine or bicine, with or without glucose and citric acid, and then heated to a temperature of 160°C. The dimensional stability, degree of chemical leaching and mechanical properties were assessed. Overall, it was concluded that neither the presence of glucose nor citric acid did appear to enhance the reactivity of tricine or bicine. Anti-swelling efficiency (ASE) of 50% was observed for combined treatments of bicine/tricine and citric acid but the leaching resistance originated mainly from citric acid and glucose, with no indication for the retention of bicine or tricine. The presence of citric acid led to a strongly reduced modulus of rupture. 

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  • 17.
    Buck, Dietrich
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Cross-Laminated Timber Mechanics2021Doctoral thesis, comprehensive summary (Other academic)
  • 18.
    Buck, Dietrich
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Multivariate Image Analysis Applied to Cross-Laminated Timber: Combined Hyperspectral Near-Infrared and X-ray Computed Tomography2023In: Journal of Spectroscopy, ISSN 2314-4920, E-ISSN 2314-4939, article id 3954368Article in journal (Refereed)
    Abstract [en]

    Engineered wood products, such as cross-laminated timber (CLT), are becoming more popular in the designs of modern sustainable buildings. This increased production of CLT requires more robust, yet less labour-intensive means to assess the material characteristics of whole CLT panels. In exploring ways of improving efficiency, this study explores multivariate image analysis (MIA) via partial least squares discriminant analysis (PLS-DA) machine learning as a means to classify CLT material features. CLT panels underwent nondestructive testing using near-infrared (NIR) hyperspectral imaging and X-ray computed tomography (CT) analysis. MIA was performed on these results to build predictive models for wood features, such as fibre alignment and knot type. The models showed that it was possible to classify material features on the surface of CLT using NIR alone; whilst when combined with X-ray data, it enhanced the predictive ability of material features throughout the CLT volume. These first results from such modelling have the potential to help map the chemical and physical material properties of CLT, improving the manufacturing efficiency of the product and allowing greater sustainability of engineered wood products.

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  • 19.
    Buck, Dietrich
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wallentén, Petter
    Division of Building Physics, Department of Building and Environmental Technology, Lund University, Lund, Sweden.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Öhman, Micael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Moisture- and mould-resistance: multi-modal modelling leveraging X-ray tomography in edge-sealed cross-laminated timber2023In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 230, article id 111967Article in journal (Refereed)
    Abstract [en]

    Edge-sealing, which involves treating the edges of wood products, improves water resistance. This study investigated the feasibility of edge-sealed cross-laminated timber (CLT) panels to reduce capillary water uptake, thereby resisting mould formation. The water and vapour permeabilities of ten characteristically different single-layer sealant coating systems were systematically determined. Multi-modal assessment leveraged by computed tomography (CT) scanning methodology was used to enhance detection of material characteristics beyond the standard coating permeability assessment. Moisture content was observed to change during the specimens’ absorption and desorption depending on the sealant system applied. The results revealed different characteristics of coatings during the water absorption and desorption stages. Findings from this study were used to develop recommendations regarding the water resistance of coating systems, curing time, susceptibility to mould formation, and industrial applicability. Results suggest that edge-sealed CLT could minimise the risk of mould formation, which can occur at worksites with minimal weather protection. The method developed in this study provides a basis to evaluate new coating systems and determine which use case is the best for a particular coating type. This study also incorporates insights from industry to identify future research orientations, which may pave the way for new designs and assessment techniques.

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  • 20.
    Báder, Mátyás
    et al.
    University of Sopron, Sopron, Hungary.
    Bak, Miklós
    University of Sopron, Sopron, Hungary.
    Németh, Róbert
    University of Sopron, Sopron, Hungary.
    Rademacher, Peter
    Mendel University in Brno, Brno, Czech Republic.
    Rousek, Radim
    Mendel University in Brno, Brno, Czech Republic.
    Horníček, Stanislav
    Mendel University in Brno, Brno, Czech Republic.
    Dömény, Jakub
    Mendel University in Brno, Brno, Czech Republic.
    Klímek, Petr
    Mendel University in Brno, Brno, Czech Republic.
    Kudela, Jozef
    Technical University in Zvolen, Zvolen, Slovakia.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Neyses, Benedikt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kutnar, Andreja
    University of Primorska, Koper, Slovenia; InnoRenew CoE, Izola, Slovenia.
    Wimmer, Rupert
    University of Natural Resources and Life Sciences, Vienna, Austria; Renewable Materials, Tulln an der Donau, Austria.
    Pfriem, Alexander
    Eberswalde University for Sustainable Development, Eberswalde, Germany.
    Wood densification processing for newly engineered materials2018In: Proceedings of the 5th International Conference on Processing Technologies for the Forest and Bio-based Products Industries (PTF BPI 2018), Freising/Münich, September 20-21 / [ed] M. C. Barbu; A. Petutschnigg; E. M. Tudor, Kuchl, 2018, p. 255-263Conference paper (Refereed)
    Abstract [en]

    Wood is a renewable, bio-based material with a mixture of different properties and qualities, used in numerous applications. Beside many species with high wood qualities several species suffer due to a number of disadvantages, where low hardness and abrasive resistance are characteristic for low-density species. This paper presents examples of on-going European research projects and industrial processes mostly related to wood densification methods. Wood densification is a classical thermohydro-mechanical (THM) wood treatment process, through which density is increased by mechanical compression of wood perpendicular to the grain, by impregnation of cell lumens or cell walls with solutions or melted substances (resins, waxes), or by a combination of both. The purpose is to produce newly designed and engineered materials and products with new property profiles, which would potentially find new markets. In general, the THM processes consist of three stages: plasticization of the wood cells, followed by the actualcompression, and finally solidification of the compressed wood in order to prevent elastic spring-back and the moisture-induced set-recovery. The wood densification process refers but is not limited to solid wood and might apply to whole wood pieces, or to local areas within given pieces only. Another THM method is the mechanical compression of wood parallel to the grain, which leads to a product with high flexibility. A European wood research network, represented by the authors of this contribution, has extended experience in many wood modification processes, as demonstrated through ongoing researches and case studies in this paper

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  • 21.
    Cool, Julie
    et al.
    University of British Columbia.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Avramidis, Stavros
    University of British Columbia.
    Knot detection in coarse resolution CT images of logs2017In: International Wood Machining Seminar (IWMS-23), 2017Conference paper (Refereed)
    Abstract [en]

    The use of X-ray computed tomography (CT) scanning of logs in sawmill is becoming a reality in the last few years, usually with rather costly and complex machines resembling medical scanners. However, a scanning solution has been developed that is less costly and more robust, and therefore more suited for sawmill needs. The rather coarse data from this machine has not been fully evaluated regarding possibilities to detect internal features such as knots. In this study, a knot detection algorithm developed for medical scanners was applied to images from a coarse resolution scanner, from four different logs of various species, and with different image resolution. The objective was to see if it was possible to detect knots automatically in the images. If so, the aim was to calculate the knot detection rate and the accuracy of detected knot size and position. These numbers were calculated compared to manually measured reference knots. This resulted in a knot detection rate of about 53 % overall, and a well detected knot position, but poorly detected knot size. It is possible to observe a certain difference between species and reconstruction resolution, however the material is too small to draw any definite conclusions. As a preliminary study, it provides input for further investigation on knot detection in coarse resolution X-ray CT images. Future work involves scanning more logs to get more data, and to pinpoint the resolution needed for accurate knot detection using the current algorithm.

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  • 22.
    Cool, Julie
    et al.
    University of British Columbia.
    Fredriksson, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Stephen, James D
    Queen’s University.
    Mabee, Warren E
    Queen’s University.
    Avramidis, Stavros
    University of British Columbia.
    Bull, Gary Q
    University of British Columbia.
    An Integrated Forest Products Cluster for Off-Grid Lumber Production Using Biomass CHP in Remote Indigenous Communities2017Conference paper (Refereed)
  • 23.
    Couceiro, José
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    X-ray computed tomography to study moisture distribution in wood2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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

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

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

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  • 24.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    Department of Ocean Operations and Civil Engineering, Faculty of Engineering, Norwegian University of Science and Technology, 6025 Ålesund, Norway.
    Mannes, David
    Paul Scherrer Insitute (PSI), Villigen, Switzerland.
    Niemz, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. ETH Zürich, Institute for Building Materials, Stefano-Franscini Platz 3, 8093 Zürich, Switzerland.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Estimation of the moisture content in wood by combination of Neutron and X-ray imaging2022In: Proceedings: 22nd International Nondestructive Testing and Evaluation of Wood Symposium / [ed] Wang, X., Ross, R.J., Madison (WI), USA: United States Department of Agriculture , 2022, p. 40-47Conference paper (Other academic)
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  • 25.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    Department of Ocean Operations and Civil Engineering, Faculty of Engineering, Norwegian University of Science and Technology, 6025 Ålesund, Norway.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Ursella, Enrico
    MicroTec GmbH, Venice, Italy.
    Industrial CT scanning in wood research2022In: Proceedings: 22nd International Nondestructive Testing and Evaluation of Wood Symposium / [ed] Wang, X., Ross, R.J., Madison (WI), USA: United States Department of Agriculture , 2022, p. 17-17Conference paper (Other academic)
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  • 26.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lin, Chia-feng
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Schleicher, Frank
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Svensson, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Mantanis, George I.
    Laboratory of Wood Science and Technology, Department of Forestry, Wood Sciences and Design, University of Thessaly, Karditsa, Greece.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Use of X-ray computed tomography for real-time studies of the fire progress in wood2023In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 18, no 6, p. 2150-2152Article in journal (Refereed)
  • 27.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lindgren, Owe
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Estimation of miosture content in wood using dual x-ray energies in a medical CT-scanner2016In: Process Technologies for the Forest & Biobased Products Industries: PTF BPI 2016, 2016, p. 22-Conference paper (Other academic)
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  • 28.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Lindgren, Owe
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    Department of Ocean Operations and Civil Engineering, Norwegian University of Science and Technology (NTNU), Ålesund, Norway.
    Söderström, Ove
    c Professor Emeritus of Building Materials, Stockholm, Sweden.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Real-time wood moisture-content determination using dual-energy X-ray computed tomography scanning2019In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 14, no 6, p. 437-444Article in journal (Refereed)
    Abstract [en]

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

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  • 29.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Neyses, Benedikt
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    In-situ moisture content and density measurements in surface densified wood using dual X-ray absorptiometry in medical CT-scanning2016In: BIOCOMP 2016: The 13th Pacific Rim Bio-Based Composites Symposium, Bio-based composites for a sustainable future., Concepción: University of Concepción , 2016, Vol. 2, p. 92-, article id NA01Conference paper (Refereed)
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  • 30.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    The use of X-ray computed tomography in bio-composite research2016In: BIOCOMP 2016: The 13th Pacific Rim Bio-Based Composites Symposium : Bio-based composites for a sustainable future,, Conceptión: University of Concepción , 2016, p. 42-45Conference paper (Refereed)
    Abstract [en]

    X-ray computed tomography (CT), which was introduced in the medical field in the early 1970s, is also a powerful tool for the non-destructive measurement of dynamic processes in wood. For more than 20 years, medical CT has been used in wood research at Luleå University of Technology. The uniqueness of the CT equipment allowsprocesses such as drying, modification; water absorption; internal and external cracking; and material deformation to be studied in temperature- and humidity-controlled environments. The data recorded by the CT scanner during the process is converted into two or three dimensional images that, for instance, can show dynamic moisture behaviour in wood drying and crack formation. This paper provides an overview of the possibilities of using CT in bio-composite research, and shows examples of applications and results that can be particularly difficult to achieve using other methods. A specific focus is on studies on wood products that use combinations with materials such as metal and especially about how to deal with the difficulties that this entails.The practical application of the result is that CT scanning, combined with image processing, can be used for non-destructive and non-contact three-dimensional s tudies of exterior construction elements during water sorption and desorption, to study parameters such as swelling and shrinking behaviour; delamination phenomena; and crack development.

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  • 31.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    X-ray computed tomography studies of moisture-content distribution in spruce boards exposed to liquid water.2020In: Proceedings of the 2020 Society of Wood Science and Technology International Convention: “Renewable Resources for a Sustainable and Healthy Future” / [ed] Susan LeVan Green, USA: Society of Wood Science and Technology (SWST) , 2020, p. 356-357Conference paper (Refereed)
    Abstract [en]

    The use of cross-laminated timber (CLT) as a construction material for high-rise timber buildings has increased in the recent years especially in Europe and North America; a trend that is expected to continue. The CLT-elements will often be finished with an impermeable layer, whether it is walls, floors and, especially, roof. In Sweden, often no weather protection is used during the construction of the building, allowing the wood to be exposed to liquid water and relaying on later atmospheric conditions to dry the timber prior to finishing. The Swedish building regulations require a maximum surface moisture content (MC) of 18% before assembly of the elements and a maximum surface MC of 16% before the wood is covered. This could drive to high levels of MC within the CLT while the surface is already dry, which is a highly possible scenario in the case of high buildings where sun and wind create good conditions for a fast surface drying. At the same time, the regulation requires control of MC to be made with an electrical pin-type MC-meter, which is problematic because its reliability lays in part on the device reaching a certain penetration into the wood. The measurement of surface MC could thus be erroneous and the risk for mould development would be high even if the regulations are strictly followed. If a CLT with a too high moisture level are covered with an impermeable surface layer, the moisture is trapped within the CLT and may cause microbiological degradation that could be problematic to correct later on.An update in the regulation requirements is recommended, but such update must be based on a proper understanding of how moisture can be distributed in CLT and other wood-based building material during outdoor construction.

    This project aims to establish amethod to study (1) the effect of liquid-water-exposure time on the MC distribution of Spruce timber boards, but that could potentially be used in other wood-based building materials as well, and (2) the drying process under emulated outdoor conditions. The focus is set on those elements that are laid horizontally or with a very low inclination, such as floors and roofs. Sections of methacrylate are glued to the internal side of 43 x 200 mm planed spruce timber, allowing the wood to be exposed to standing water under a period of several days. CT images of different cross sections are taken periodically so that the evolution of MC profile can be monitored. The hypothesis is that the suction of liquid water will not be large and that it can dry quickly once the exposure to liquid water ends, but also that a MC gradient will develop beneath the surface which, under drying, may create regions of high MC that may be unnoticed by measuring with pin-type MC-meters.

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  • 32.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kapillärt vattenupptag tvärs fibrerna i KL‐trä – Studier i CT: Slutrapport2021Report (Other academic)
    Abstract [en]

    The project aimed to study capillary water and moisture absorption through diffusion in spruce boards across fiber direction when exposed to liquid water for 168 h, as well as the drying after that. The study was driven by the necessity of fulfilling the HusAMA YSC.122 rule that states that the surface MC of the wood must not be above 18 % when it is built in and above 16 % if surface treatment will be done. CT scanning was used to study changing MC levels in 2.25 mm layers from the wood surface as average values for each layer. The layers are named after the deepest section of the layer i.e. layer 4.5 is between 2.25 mm and 4.5 mm.

    Water uptake: Results of the studies show that liquid water can penetrate down to 4.5 mm (MC >30%), even though in most cases it does not penetrate beyond 2.25 mm (surface layer). Local pockets or higher MC may nevertheless occur. None of the specimens shows liquid water penetration beyond the surface layer within the first 72 h of liquid water exposure. Neither density nor board side exposed (pith‐side or sapwood‐side) have an influence in the rate of liquid water/moisture absorption. Regarding the 18% limit established by HusAMA YSC.122, it can be reached within the first 24 hours of exposure, but its penetration is limited to around 6.75 mm of depth. Regarding the 16 % limit, a more heterogeneous behavior among specimens can be seen, with penetrations that go from 13.5 mm to 20.25 mm after 24 h of exposure.

    Drying: Drying took place by samples kept in room climate in the lab with no climate control or air‐velocity regulation. The conditions were equivalent to EMC of 6 %. All layers of the wood specimens are below 18 % within 48 h when water is removed after 168 h of exposure. The 16 % limit can take from 48 to up to 140 h to be reached by all layers in the atmospheric conditions of the lab, which at the moment of the experiment were extremely dry. This factor must be taken into account when interpreting results of this experiment not only during drying, but also during water uptake. 

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  • 33.
    Couceiro, José
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sehlstedt-Persson, Margot
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Hansson, Lars
    Norwegian University of Science and Technology (NTNU), Department of ICT and Natural Sciences, Norway.
    Hagman, Olle
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    CT scanning of capillary phenomena in bio-based materials2017In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 13, no 4, p. 181-187Article in journal (Refereed)
    Abstract [en]

    X-ray computed tomography (CT) is a powerful tool for the non-destructive study of dynamic moisture processes in wood and other bio-based materials. In the CT facilities at Luleå University of Technology, it is possible to study wood-moisture relations such as water absorption, drying and related material deformation under a temperature- and humidity-controlled environment.An increase in the use of bio-based materials in building construction has led to an increased interest in capillary phenomena in these materials, because of an increasing number of moisture-related damage in timber and hybrid-timber buildings. This article shows some examples of how different bio-materials used in construction interact with liquid water over time. The overall purpose has been to develop the CT technique as a powerful tool for the determination and visualization of capillary flow that can be a base for modelling and an increased understanding of moisture flow in new bio-based building materials.Early-stage observation of the behaviour of different traditional and new bio-based building materials shows that CT scanning, combined with image processing, has a high potential to be used in performing non-destructive and non-contact tests that can help to increase the knowledge of water-material interactions and develop building materials with an optimized performance.

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  • 34.
    Cristescu, Carmen
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Markers of quality in self-bonded beech boards2017Conference paper (Refereed)
    Abstract [en]

    A self-bonding phenomenon takes place when five layers of beech (Fagus SylvaticaL.) veneers are pressed at temperatures higher than 200ºC. If the pressing temperature between veneer surfaces reaches at least 225ºC during pressing and if the pressure applied is optimal, water-resistant bonds are formed between veneers. This study investigates the relation of thickness reduction (marker of compression) and mass loss (marker of heat treatment intensity) to boards quality. The effect of water and water vapour on the bondings between veneer in boards pressed at 200, 225 and 250ºC is studied. The conclusion is that pressing 5 layers of 2 mm rotary-cut beech veneer parallel-fibered at 225ºC, 5 MPa and 300 s leads to a thickness reduction of 33.4 % and mass loss of 1.23 %; in such boards bondings are not resistant to liquid water but are resistant to vapour after one adsorption-desorption cycle. When pressing at 250ºC, 5 MPa and 300 seconds, the thickness reduction is 50% and the mass loss 4%; in such boards no delamination was observed when soaked in water. Boards pressed athigher temperature show lower hygroscopicity. Their equilibrium moisture content (EMC) rangedbetween 3.6 and 7%. Based on the results of this study it ishypothesised that the decay resistance of self-bonded boards will increase when increasing the severity of the hot-pressing.

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  • 35.
    Deliiski, Nencho
    et al.
    Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Niemz, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Institute for Building Materials, ETH Zürich, Zürich, Switzerland.
    Angelski, Dimitar
    Department of Furniture Production, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Campean, Mihaela
    Department of Woodprocessing and Design of Wood Products, Faculty of Furniture Design and Wood Engineering, Transilvania University of Braşov, Braşov, Romania.
    Vitchev, Pavlin
    Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    An engineering approach for calculating the energy required for defrosting and subsequent heating of frozen wood during thermal treatment2024In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280Article in journal (Refereed)
  • 36.
    Deliiski, Nencho
    et al.
    Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Niemz, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Institute for Building Materials, ETH Zürich, Zürich, Switzerland.
    Angelski, Dimitar
    Department of Furniture Production, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Tumbarkova, Natalia
    Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    A methodology for computing the relative icing degrees of logs stored in an open warehouse at ambient air temperature in winter2021In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 16, no 6, p. 421-428Article in journal (Refereed)
    Abstract [en]

    This paper describes a methodology for mathematical modeling, computing, and research of two mutually connected problems: 2D non-stationary temperature distribution in logs stored for a long time in an open warehouse at periodically changing ambient air temperature in winter and change in the icing degrees of the logs during this time. Mathematical descriptions of the periodically changing ambient air temperature and of three types of relative icing degree of the logs that result under the influence of that temperature have been presented. These descriptions are introduced in coupled 2D non-linear mathematical models of the heat distribution in logs during their freezing and defrosting. The paper presents solutions of the models with explicit form of the finite-difference method. Results from a simulative investigation of the 2D non-stationary temperature distribution, average mass temperature, and three types of icing degree of beech logs with industrial dimensions (diameter of 0.4 m and length of 0.8 m), moisture content of 0.6 kg·kg−1, and initial temperature of 0°C during their 5 days and nights alternating freezing and defrosting in an open warehouse at sinusoidal change of the ambient air temperature with various initial values below −5°C and different amplitudes are graphically presented and analyzed. 

  • 37.
    Deliiski, Nencho
    et al.
    Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Niemz, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Institute for Building Materials, ETH Zürich, Zürich, Switzerland.
    Dzurenda, Ladislav
    Department of Woodworking, Faculty of Wood Science and Technology, Technical University in Zvolen, Zvolen, Slovakia.
    Vitchev, Pavlin
    Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Angelski, Dimitar
    Department of Furniture Production, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    An approach for computing the thermal balance and energy consumption of concrete pits during boiling of frozed logs for veneer production2023In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 18, no 6, p. 2153-2163Article in journal (Refereed)
  • 38.
    Deliiski, Nencho
    et al.
    Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Niemz, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Institute for Building Materials, ETH Zürich, Zürich, Switzerland.
    Vitchev, Pavlin
    Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Angelski, Dimitar
    Department of Furniture Production, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Tumbarkova, Natalia
    Department of Woodworking Machines, Faculty of Forest Industry, University of Forestry, Sofia, Bulgaria.
    Computing the duration of regimes for autoclave steaming of frozen wooden prisms under variable operating conditions in veneer production2022In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 17, no 6, p. 451-458Article in journal (Refereed)
  • 39.
    Duarte, Sónia
    et al.
    LEAF (Linking Landscape, Environment, Agriculture and Food) Research Centre, Instituto Superior de Agronomia, Universidade de Lisboa. Tapada da Ajuda, 1349-017 Lisboa, Portugal.
    Nunes, Lina
    LNEC, National Laboratory for Civil Engineering, Structures Department, Av. do Brasil, 101, 1700-066 Lisbon, Portugal. cE3c, Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group, University of the Azores, 9700–042 Angra do Heroísmo, Portugal.
    Kržišnik, Davor
    Biotechnical Faculty, University of Ljubljana, SI-1000 Ljubljana, Slovenia.
    Humar, Miha
    Biotechnical Faculty, University of Ljubljana, SI-1000 Ljubljana, Slovenia.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 1176, 16521 Praha 6–Suchdol, Czech Republic.
    Influence of Zwitterionic Buffer Effects with Thermal Modification Treatments of Wood on Symbiotic Protists in Reticulitermes grassei Clément2021In: Insects, E-ISSN 2075-4450, Vol. 12, no 2, article id 139Article in journal (Refereed)
    Abstract [en]

    The majority of thermal modification processes are at temperatures greater than 180 °C, resulting in a product with some properties enhanced and some diminished (e.g., mechanical properties). However, the durability of thermally modified wood to termite attack is recognised as low. Recent attempts at combining thermal modification with chemical modification, either prior to or directly after the thermal process, are promising. Buffers, although not influencing the reaction systems, may interact on exposure to certain conditions, potentially acting as promoters of biological changes. In this study, two zwitterionic buffers, bicine and tricine, chosen for their potential to form Maillard-type products with fragmented hemicelluloses/volatiles, were assessed with and without thermal modification for two wood species (spruce and beech), with subsequent evaluation of their effect against subterranean termites (Reticulitermes grassei Clément) and their symbiotic protists. The effect of the wood treatments on termites and their symbionts was visible after four weeks, especially for spruce treated with tricine and bicine and heat treatment (bicine HT), and for beech treated with bicine and bicine and heat treatment (bicine HT). The chemical behaviour of these substances should be further investigated when in contact with wood and also after heat treatment. This is the first study evaluating the effect of potential Maillard reactions with zwitterionic buffers on subterranean termite symbiotic fauna.

  • 40.
    Dvořák, Ondřej
    et al.
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 00 Prague, Czech Republic.
    Kvietková, Monika Sarvašová
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 00 Prague, Czech Republic.
    Šimůnková, Kristýna
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 00 Prague, Czech Republic.
    Machanec, Ondřej
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 00 Prague, Czech Republic.
    Pánek, Miloš
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 00 Prague, Czech Republic.
    Pastierovič, Filip
    Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 00 Prague, Czech Republic.
    Lin, Chia-Feng
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Department of Wood Processing and Biomaterials, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 00 Prague, Czech Republic.
    The Influence of the Initial Treatment of Oak Wood on Increasing the Durability of Exterior Transparent Coating Systems2023In: Polymers, E-ISSN 2073-4360, Vol. 15, no 15, article id 3251Article in journal (Refereed)
    Abstract [en]

    This study determined the impact of undertaking an initial treatment of oak wood by sealing its surface pores with epoxy resin, focusing on the durability of transparent coating systems when exposed outdoors. Throughout the exposure period, various parameters including color, gloss, surface wettability, and both macroscopic and microscopic surface evaluation were continuously monitored. The study involved two sets of samples: one set underwent the pretreatment, while the other did not. Subsequently, four coating systems were applied to the samples, comprising two solvent-based and two water-based coatings. The experiment was conducted over a period of two years, utilizing natural weathering methods within the premises of the Czech University of Life Sciences in Prague. The pretreatment with epoxy resin exhibited enhanced durability for all paint systems. The analysis showed a significant difference in gloss and color after 12 months of weathering exposure without any significant effect on surface wettability and sealing. However, after 24 months of the weathering exposure, no significant differences between the sealed and unsealed surface were observed. The most significant change in properties was noted for the water-based coatings used in coating systems number 3 and 4, and these coatings were rated as the best.

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  • 41.
    Ekevad, Mats
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Huber, Johannes A.J.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Jacobsson, Peter
    Martinsons Träbroar AB.
    Mechanics of stress-laminated timber bridges with butt end joints2017Conference paper (Refereed)
    Abstract [en]

    A number of variants of single span and three-span stress-laminated timber bridge decks have been studied via finite element simulations and experiments. Glulam beams in the decks were in general shorter than the total length of span which means that there were butt end joints in the decks. The butt end of each beam in a joint was not connected to the other beam which means that each butt end joint reduced the strength and stiffness of the whole of the deck. Results for deflection and stresses were examined for the studied variants in the form of reduction factors for strength and stiffness relative to a deck without butt end joints.

    Factors are shown in diagrams as function of ratio butt end distance/beam width and also butt end distance/span width. Comparison of achieved results with existing Eurocode rules shows that Eurocode rules are not totally appropriate.

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  • 42.
    Elbeltagi, Ahmed
    et al.
    Faculty of Agriculture, Agricultural Engineering Department, Mansoura University, Mansoura, 35516, Egypt.
    Raza, Ali
    School of Agricultural Engineering, Jiangsu University, Zhenjiang, 212013, People’s Republic of China.
    Hu, Yongguang
    School of Agricultural Engineering, Jiangsu University, Zhenjiang, 212013, People’s Republic of China.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Kushwaha, N. L.
    Division of Agricultural Engineering, ICAR–Indian Agriculture Research Institute, New Delhi, 110012, India.
    Srivastava, Aman
    Department of Civil Engineering, Indian Institute of Technology (IIT) Kharagpur, Kharagpur, 721302, West-Bengal, India.
    Kumar Vishwakarma, Dinesh
    Department of Irrigation and Drainage Engineering, G.B. Pant, University of Agriculture and Technology, Pantnagar, Uttarakhand, 263145, India.
    Zubair, Muhammad
    School of Transportation, Southeast University, Nanjing, 21009, China.
    Data intelligence and hybrid metaheuristic algorithms-based estimation of reference evapotranspiration2022In: Applied water science, ISSN 2190-5487, E-ISSN 2190-5495, Vol. 12, no 7, article id 152Article in journal (Refereed)
    Abstract [en]

    For developing countries, scarcity of climatic data is the biggest challenge, and model development with limited meteorological input is of critical importance. In this study, five data intelligent and hybrid metaheuristic machine learning algorithms, namely additive regression (AR), AR-bagging, AR-random subspace (AR-RSS), AR-M5P, and AR-REPTree, were applied to predict monthly mean daily reference evapotranspiration (ET0). For this purpose, climatic data of two meteorological stations located in the semi-arid region of Pakistan were used from the period 1987 to 2016. The climatic dataset includes maximum and minimum temperature (Tmax, Tmin), average relative humidity (RHavg), average wind speed (Ux), and sunshine hours (n). Sensitivity analysis through regression methods was applied to determine effective input climatic parameters for ET0 modeling. The results of performed regression analysis on all input parameters proved that Tmin, RHAvg, Ux, and n were identified as the most influential input parameters at the studied station. From the results, it was revealed that all the selected models predicted ET0 at both stations with greater precision. The AR-REPTree model was located furthest and the AR-M5P model was located nearest to the observed point based on the performing indices at both the selected meteorological stations. The study concluded that under the aforementioned methodological framework, the AR-M5P model can yield higher accuracy in predicting ET0 values, as compared to other selected algorithms.

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  • 43.
    Elragal, Rawan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Digital Services and Systems.
    Elragal, Ahmed
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Digital Services and Systems.
    Habibipour, Abdolrasoul
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Digital Services and Systems.
    Food Analytics – A Literature Review and Ways Forward2024In: 2024 23rd International Symposium INFOTEH-JAHORINA (INFOTEH): Proceedings, 2024Conference paper (Refereed)
  • 44.
    Emami, Somayeh
    et al.
    Department of Water Engineering, University of Tabriz, Tabriz, Iran.
    Dehghanisanij, Hossein
    Agricultural Research, Education and Extension Organization, Agricultural Engineering Research Institute, P.O. Box 31585-845, Karaj, Alborz, Iran.
    Achite, Mohammed
    Laboratory of Water and Environment, Faculty of Nature and Life Sciences, Hassiba Benbouali University of Chlef, 02180, Chlef, Algeria.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Linh, Nguyen Thi Thuy
    Institute of Applied Technology, Thu Dau Mot University, Binh Duong Province, Vietnam.
    Application of ANFIS, ELM, and ANN models to assess water productivity indicators based on agronomic techniques in the Lake Urmia Basin2023In: Applied water science, ISSN 2190-5487, E-ISSN 2190-5495, Vol. 13, no 2, article id 55Article in journal (Refereed)
    Abstract [en]

    Water productivity (WP) is one of the most important critical indicators in the essential planning of water consumption in the agricultural sector. For this purpose, the WP and economic water productivity (WPe) were estimated using agronomic technologies. The impact of agronomic technologies on WP and WPe was carried out in two parts of field monitoring and modeling using novel intelligent approaches. Extreme learning machine (ELM), adaptive neuro-fuzzy inference system (ANFIS), and artificial neural network (ANN) methods were used to model WP and WPe. A dataset including 200 field data was collected from five treatment and control sections in the Malekan region, located in the southeast of Lake Urmia, Iran, for the crop year 2020–2021. Six different input combinations were introduced to estimate WP and WPe. The models used were evaluated using mean squared error (RMSE), relative mean squared error (RRMSE), and efficiency measures (NSE). Field monitoring results showed that in the treatment fields, with the application of agronomic technologies, the crop yield, WP, and WPe increased by 17.9%, 30.1%, and 19.9%, respectively. The results explained that irrigation water in farms W1, W2, W3, W4, and W5 decreased by 23.9%, 21.3%, 29.5%, 16.5%, and 2.7%, respectively. The modeling results indicated that the ANFIS model with values of RMSE = 0.016, RRMSE = 0.018, and NSE = 0.960 performed better in estimating WP and WPe than ANN and ELM models. The results confirmed that the crop variety, fertilizer, and irrigation plot dimensions are the most critical influencing parameters in improving WP and WPe.

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  • 45.
    Esteves, Bruno
    et al.
    Department of Wood Engineering, Polytechnic Institute of Viseu, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal; Centre for Natural Resources, Environment and Society-CERNAS-IPV Research Centre, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal.
    Ferreira, Helena
    Department of Environmental Engineering, Polytechnic Institute of Viseu, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal.
    Viana, Hélder
    Department of Ecology and Sustainable Agriculture, Polytechnic Institute of Viseu, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal; Centre for the Research and Technology of Agro-Environmental and Biological Sciences-CITAB, University of Trás-os-Montes and Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal.
    Ferreira, José
    Department of Wood Engineering, Polytechnic Institute of Viseu, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal; Centre for Natural Resources, Environment and Society-CERNAS-IPV Research Centre, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal.
    Domingos, Idalina
    Department of Wood Engineering, Polytechnic Institute of Viseu, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal; Centre for Natural Resources, Environment and Society-CERNAS-IPV Research Centre, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal.
    Cruz-Lopes, Luísa
    Centre for Natural Resources, Environment and Society-CERNAS-IPV Research Centre, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal; Department of Environmental Engineering, Polytechnic Institute of Viseu, Av. Cor. José Maria Vale de Andrade, 3504-510 Viseu, Portugal.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Department of Forestry and Biomaterials, Czech University of Life Sciences, Kamýcká 1176, Praha 6, 16521 Suchdol, Czech Republic.
    Nunes, Lina
    Structures Department, LNEC, National Laboratory for Civil Engineering, Av. do Brasil, 101, 1700-066 Lisbon, Portugal; Centre for Ecology, Evolution and Environmental Changes (cE3c), Rua Capitão João d’Ávila, 9700-042 Angra do Heroísmo, Portugal; Azorean Biodiversity Group, University of Azores, Rua Capitão João d’Ávila, 9700-042 Angra do Heroísmo, Portugal.
    Termite Resistance, Chemical and Mechanical Characterization of Paulownia tomentosa Wood before and after Heat Treatment2021In: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 12, no 8, article id 1114Article in journal (Refereed)
    Abstract [en]

    The introduction of new species in forest management must be undertaken with a degree of care, to help prevent the spread of invasive species. However, new species with higher profitability are needed to increase forest products value and the resilience of rural populations. Paulownia tomentosa has an extremely fast growth. The objective and novelty of this work was to study the potential use of young Paulownia trees grown in Portugal by using heat treatment to improve its properties, thereby allowing higher value applications of the wood. The average chemical composition of untreated and heat-treated wood was determined. The extractive content was determined by successive Soxhlet extraction with dichloromethane (DCM), ethanol and water as solvents. The composition of lipophilic extracts was performed by injection in GC-MS with mass detection. Insoluble and soluble lignin, holocellulose and α-cellulose were also determined. Physical (density and water absorption and dimensional stability) and mechanical properties (bending strength and bending stiffness) and termite resistance was also determined. Results showed that extractive content increased in all solvents, lignin and α-cellulose also increased and hemicelluloses decreased. Compounds derived from the thermal degradation of lignin were found in heat-treated wood extractions. Dimensional stability improved but there was a decrease in mechanical properties. Resistance against termites was better for untreated wood than for heat-treated wood, possibly due to the thermal degradation of some toxic extractives.

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  • 46.
    Faisal, Ayad A. H.
    et al.
    Department of Environmental Engineering, College of EngineeringUniversity of Baghdad.
    Kubba, Faris A.
    Department of Environmental Engineering, College of EngineeringUniversity of Al-Mustansiriyah.
    Madhloom, Huda M.
    Department of Civil Engineering, College of EngineeringUniversity of Al-Mustansiriyah.
    Modeling of Trichloroethylene Migration in Three-Dimensional Saturated Sandy Soil2014In: Arabian Journal for Science and Engineering, ISSN 2193-567X, Vol. 39, no 11, p. 7763-7769Article in journal (Refereed)
    Abstract [en]

    This study characterized the temporal and spatial distribution of trichloroethylene (TCE) dissolved plume from continuous source in 3D bench-scale sand aquifer. COMSOL Multiphysics 3.5a (2008) software based on the finite element numerical scheme taking into account the sorption process was used to interpreted the experimental results. A conservative tracer is employed for the determination of the longitudinal dispersivity. The sorption characteristics of TCE onto the aquifer sand are independently determined from batch equilibrium data. TCE concentrations at specific downstream locations within the aquifer for different periods of time are measured under flow rates values equal to 20, 40 and 100 ml/min. The predicted TCE concentrations were found to be reasonably agreed with the bench-scale experimental results with mean error <5%.

  • 47.
    Fašalek, Andrej
    et al.
    Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
    Straže, Aleš
    Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
    Šega, Bogdan
    Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
    Huber, Johannes Albert Josef
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Šernek, Milan
    Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
    Bonding Performance of Melamine–Urea–Formaldehyde and Polyurethane Adhesives for Laminated Hybrid Beams and Their Selected Mechanical Properties2023In: Buildings, E-ISSN 2075-5309, Vol. 13, no 8, article id 2087Article in journal (Refereed)
    Abstract [en]

    Beech (Fagus Sylvatica L.) is a prevalent tree species in Slovenia and is suitable for manufacturing glulam beams. However, beech wood has certain limitations that can potentially be mitigated by combining it with Norway spruce (Picea abies (L.) Karst.) wood to create hybrid beams. This study aimed to determine the bonding performance of commonly used melamine–urea–formaldehyde and polyurethane adhesives for these hybrid beams. Moreover, how varying the proportion of beech wood in a hybrid beam affects its mechanical properties was examined. Shear and delamination tests (method B) were conducted, and EN 14080:2013 requirements were met in all cases. The four-point bending tests of the beams showed that hybrid beams containing 20% of beech wood in the cross-sectional height on each side of the neutral axis exhibited a similar modulus of elasticity values as pure beech beams, but their strength was not equally improved. Hybrid beams with 11% of beech wood did not show any improvement in bending stiffness or strength compared to pure spruce beams. It was noted that the presence of beech wood in a hybrid beam can influence its failure mode. Furthermore, analytical calculations showed that a symmetrical lay-up is preferable to an asymmetrical one to increase the effective modulus of elasticity.

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  • 48.
    Ferreira, José
    et al.
    Research Center for Natural Resources, Environment and Society (CERNAS), Instituto Politécnico De Viseu, Campus Politécnico De Repeses, Viseu, Portugal.
    Jones, Dennis
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Esteves, Bruno
    Research Center for Natural Resources, Environment and Society (CERNAS), Instituto Politécnico De Viseu, Campus Politécnico De Repeses, Viseu, Portugal.
    Cruz-Lopes, Luisa
    Research Center for Natural Resources, Environment and Society (CERNAS), Instituto Politécnico De Viseu, Campus Politécnico De Repeses, Viseu, Portugal.
    Pereira, Helena
    Forest Research Centre, School of Agriculture, University of Lisbon, Lisbon, Portugal.
    Domingos, Idalina
    Research Center for Natural Resources, Environment and Society (CERNAS), Instituto Politécnico De Viseu, Campus Politécnico De Repeses, Viseu, Portugal.
    Life Cycle Assessment of Maritime Pine Wood: A Portuguese Case Study2021In: Journal of Sustainable Forestry, ISSN 1054-9811, E-ISSN 1540-756X, Vol. 40, no 5, p. 431-445Article in journal (Refereed)
    Abstract [en]

    Life Cycle Assessment has become one of the most recognized and internationally accepted method for examining the environmental performance of forest products and processes. The main aim of this study was to evaluate the potential environmental impact associated with different commercial outputs of maritime pine wood (round, industrial, and residual) produced in the Portuguese forest under natural regeneration. Identifying the hotspots in the life cycle (cradle-to-gate) of each sort of maritime pine was another objective of the study. SimaPro software was used for this study, whilst the CML-IA (baseline) method was chosen to assess the environmental impacts. The study showed that round wood presented the highest values in all impact categories and industrial wood presented the lowest values except in photochemical oxidation where residual wood was the best co-product when economic allocation is chosen. The major hot spots appeared to be the felling and hauling processes due to fossil fuel combustion in the chainsaw and forwarder, respectively. The co-product that should be more environmentally friendly considerably depends on the allocation procedure chosen.

  • 49.
    Florisson, Sara
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Applied Mechanics, Uppsala University, Uppsala, Sweden.
    Hansson, Lars
    Ocean Operations and Civil Engineering, Norwegian University of Science and Technology, Ålesund, Norway.
    Couceiro, José
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Sandberg, Dick
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Macroscopic X-ray computed tomography aided numerical modelling of moisture flow in sawn timber2022In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 80, no 6, p. 1351-1365Article in journal (Refereed)
    Abstract [en]

    Mathematical models are essential for the development of schedules for the air-circulation drying of timber in Swedish sawmills, but earlier models have been shown to be conservative leading to longer drying times than necessary. In the current study, macroscopic (macro) X-ray computed tomography (CT) has been used in both the development and validation of a finite element (FE) model, to enable the macro-CT aided FE modelling of the nonlinear transient moisture flow in wood. The model uses more advanced theory than has previously been used in Swedish sawmills, by incorporating a surface emission coefficient to simulate the surface resistance to moisture flow. A single piece of Norway spruce [Picea abies (L.) Karst.] timber was subjected to that part of a traditional kiln-drying schedule, which is associated with diffusion-driven moisture transport. The incorporation of macro-CT data into the FE model resulted in a more realistic representation of the board’s geometry, the initial moisture state, and the definition of material parameters. It also led to a better simulation of flow speed and moisture gradient, especially the asymmetric MC development within the cross section throughout the drying process.

  • 50.
    Florisson, Sara
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Vessby, Johan
    Department of Engineering and Chemical Science, Karlstad University, Karlstad, Sweden.
    Ormarsson, Sigurdur
    Department of Building Technology, Linnaeus University, Växjö, Sweden.
    A three-dimensional numerical analysis of moisture flow in wood and of the wood's hygro-mechanical and visco-elastic behaviour2021In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 55, no 5, p. 1269-1304Article in journal (Refereed)
    Abstract [en]

    A three-dimensional numerical model was employed in simulating nonlinear transient moisture flow in wood and the wood's hygro-mechanical and visco-elastic behaviour under such conditions. The model was developed using the finite element software Abaqus FEA, while taking account of the fibre orientation of the wood. The purpose of the study was to assess the ability of the model to simulate the response of wood beams to bending and to the climate of northern Europe. Four-point bending tests of small and clear wood specimens exposed to a constant temperature and to systematic changes in relative humidity were conducted to calibrate the numerical model. A validation of the model was then performed on the basis of a four-point bending test of solid timber beams subjected to natural climatic conditions but sheltered from the direct effects of rain, wind and sunlight. The three-dimensional character of the model enabled a full analysis of the effects of changes in moisture content and in fibre orientation on stress developments in the wood. The results obtained showed a clear distinction between the effects of moisture on the stress developments caused by mechanical loads and the stress developments caused solely by changes in climate. The changes in moisture that occurred were found to have the strongest effect on the stress state that developed in areas in which the tangential direction of the material was aligned with the exchange surface of the beams. Such areas were found to be exposed to high-tension stress during drying and to stress reversal brought about by the uneven drying and shrinkage differences that developed between the outer surface and the inner sections of the beams.

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