lnu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
12 1 - 50 av 56
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Fackler, Karin
    Vienna University of Technology, Austria.
    Ters, Thomas
    Vienna University of Technology, Austria.
    Braovac, Susan
    University of Oslo, Norway.
    A nano to macroscale study on structure-mechanics relationships of archaeological oak2013Ingår i: Journal of Cultural Heritage, ISSN 1296-2074, E-ISSN 1778-3674, Vol. 14, nr 5, 377-388 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mechanical properties of wood at different length scales of its hierarchical structure are governed by structural and compositional properties on smaller length scales. This opens up the possibility to use microstructural data for estimating mechanical properties, which are difficult to assess by conventional, destructive testing but are nevertheless of high relevance for conservation practice. Herein, we investigate such microstructure-mechanics relationships for a particular example, namely the load bearing archaeological oak of the Oseberg Viking ship, displayed at the Viking Ship Museum in Oslo, Norway. In order to identify the effects of degradation on the mechanical behavior and their relations to the microstructure, recent oak specimens of different geographical origin (Norway and Austria) are investigated as well. Wood exhibits a cellular structure. Its cell walls are composed of an amorphous polymer matrix consisting of lignin and hemicelluloses and embedded, stiff cellulose fibers. At the cell level, experimental studies comprised microscopic investigations of the cellular structure, chemical analyses of the composition of the cell walls, as well as nanoindentation tests on single cell walls. The same samples were also analyzed on the macroscopic level, where additionally mass density and annual ring data were measured together with ultrasonic stiffnesses. The chemical data clearly indicate deterioration in the archaeological oak, affecting mainly hemicelluloses and amorphous cellulose. At the cell wall scale, however, this does not necessarily lead to a weaker material behavior. The nanoindentation modulus, as a measure of the cell wall stiffness, was found to even increase. This is counterintuitive to our understanding of the effects of chemical degradation. It might be due to possible modification of lignin in the Oseberg oak, and thus have a stronger effect on the indentation modulus than the concurrent weakening of the interfaces between the load-carrying cellulose fibers and the connecting cell wall matrix when analyzing wood at the microscopic level. A similar effect is also observed for the transversal stiffness of macroscopic samples, which increases. In tension-dominated loading modes, however, the degradation of the interfaces is the dominant effect, resulting for example in a considerable reduction of the macroscopic stiffness in longitudinal direction. This underlines the utmost relevance of the loading condition on the remaining load-carrying capacity of degraded wood. On the macroscale, effects of the geographical origin (i.e. growth conditions) on ring characteristics of the oak tissues override the effects of degradation on the mechanical behavior. They have to be carefully extracted in order to come up with conclusions on the effect of degradation from macroscopic test results. The identified microstructure-mechanics relationships provide the basis for–in further research steps–building mathematical models describing the relations between microstructural characteristics and macroscopic mechanical properties and, thereon, for structural analyses of historical wooden objects.

  • 2.
    Nilsson, Jonaz
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    A new light-weight panel for interior joinery and furniture2013Ingår i: Proceeding of 9th Meeting of the Northern European Network for Wood Science and Engineering -WSE 11-12 September 2013, Hannover, Germany / [ed] Brischke, Christan & Meyer, Linda, Hannover: Leibnitz Universität Hannover , 2013, 184-189 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Light-weight materials based on wood for interior fittings and furniture have been of interest for at least the last fifty years, mainly for cost-reducing reasons. Today, the increasing care of the environment and the growing interest in the concept of a sustainable society provide further impulses for the development of light-weight materials. A common consequence of the reduction in weight of such materials is deterioration in the mechanical properties, e.g. strength, stiffness and shape stability, compared to those of solid wood. New solutions for e.g. connections and mountings are also needed. Today, new panel materials are required where the disadvantages of conventional light-weight materials are less prominent and with aesthetic and tactile properties close to those of natural wood.

    In this paper, a new type of light-weight panel is presented. The panel is cross-laminated in three layers and consists throughout of solid wood. The weight reduction is a consequence of the hollow middle-layer construction. The intention of the construction is to make it possible to mix species in the panel, e.g. a high-quality and high-density wood on the surface and a low-quality wood with low weight in the core, and thus to optimize the properties of the panel for a specific purpose and to keep costs down at the same time. In this first study, however, the whole panel is made of Scots pine.

    Bending tests show that the glue-line between the outer layers and the core is critical for the mechanical performance of the panel and this has to be developed further.

    This study shows that this light-weight panel can be used as a single component or in a system with other components for interior fittings and furniture. The current design of this light-weight panel has some deficiencies but, in addition to its low weight, it has the potential to provide the mechanical, aesthetic and tactile properties asked for.

  • 3.
    Trischler, Johann
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    An approach to estimate the productivity of various species on sites in Sweden by choosing individual climate and productivity values and the MIAMI-model with modifications.2013Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The literature contains a large variety of bioclimate, climate, biometric models for estimating the production of different species or stands under specific conditions for a defined site, or general models giving a worldwide overview of a single species. Depending on the model used, the amount of input-data varies considerable and is often related to a large investment in time and money.

    The purpose of this study was to create a model to estimate the productivity of various species of interest for biomass production using only easy available input data defining the site conditions. Further, if the site-specific input-data is the same for all species, the model allows a comparison of different species on a single site. For this approach, the MIAMI-model of Lieth et al. was used as basic model with some modifications.

    This modified model differs from recently developed models regarding the combination of species-unspecific site data and the species-specific productivity data. As the site data change with geographical location, easy handling data are profitable. The species-specific data require more extensive investigation, but once established as a database they can be used for all sites without changes. Mean annual temperature and mean annual precipitation were chosen as site-defining data and the mean annual temperature of the native distribution area of each species in combination with the highest biomass production found in the literature were chosen as the species-specific data. This combination makes this model very efficient to estimate the productivity of various species on different sites once the database is established.

    This first version of the model is restricted to sites in Sweden where changes in soil and groundwater level are relatively small. Vegetation is then mainly controlled by energy input expressed for example as temperature or irradiation. As the maximum biomass production is estimated, lower nutrient and water supplies in the soil lead primary to a decrease in biomass production, but this negative impact can be influenced by culture and treatment such as fertilising which is common in conventional agriculture. When extended to other regions with a more Mediterranean climate, for example, the impact of soil, water-storage and distribution of precipitation has to be evaluated first and if necessary included in the model formulation.

    A validation of this model with data from the literature on the one hand and data estimated by another model on the other hand showed that it seems to be possible to use the model for purposed suggested here.

  • 4.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Basic knowledge of wood properties for improved performance of laminated Veneer products2013Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 9, nr 4, 549-556 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To ensure success in the production of laminated veneer products, it is necessary to acquire a sound basic understanding of the behaviour of the wood, and to understand the inherent reactions of wood to adhesive, heat, moisture, strain and stress. This can ensure an efficient wood utilization and promote the development of new processes and products that take advantage of the visco-elastic nature of wood.

     

    A shortcoming of the laminated bending process is that the products may become distorted after moulding and during use. In this study, we have examined how the performance of laminated veneer products can be improved through the implementation of basic knowledge of wood in the design and production process.

     

    The results show that the material and process parameters and storage in a changing relative humidity have a clear impact on distortion. Fibre orientation of the veneers in the moulded assembly was the most critical parameter to control. Fibre deviations mainly resulted in twist of the product. A moisture content in one veneer deviating from that of the rest of the veneers in the assembly before moulding resulted in distortion of the laminated veneer products both after moulding and during use. To decrease the negative effect of fibre orientation and moisture content on shape stability, the veneer should be straight-grained and well-conditioned to a moisture level adapted to the use of the final product. Special care should also be taken to orientate the veneers during assembly before moulding.

  • 5.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Trischler, Johann
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Luleå University of Technology.
    Bio-based adhesives for the wood industry: an opportunity for the future?2013Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 9, nr 4, 118-125 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reviews the use of some of the new technologies that may be implemented in bio-based adhesives, e.g. carbohydrate polymers, proteins, tannins, lignins, and vegetable oils.

    In order to take a part of the market share, an adhesive should have low production costs, fulfil the environmental and health standards and give better properties than conventional synthetic adhesives. For large-volume wood products such as chipboard, it is essential to develop adhesives that enable the product to be cost competitive. Bio-based adhesives that are available and affordable for the wood industry suffer from three main problems: low moisture resistance, low reactivity and poor adhesive properties, and in several cases they are expensive compared to synthetic adhesives.

  • 6.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Thessaly, Greece.
    Voulgaridis, Elias
    Aristotle University of Thessaloniki, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    CARACTERISTICILE MATERIALULUI FIBROS ŞI PROPRIETĂŢILEHÂRTIEI RECICLATE FOLOSITE ÎN FABRICAREA CARTONULUIONDULAT: Morphology and identification of fibre furnish components of papers used in the production of corrugated board2013Ingår i: 7th International Symposium on Advanced Technologies for the Pulp, Paper and Corrugated Board Industry, 2013Konferensbidrag (Refereegranskat)
    Abstract [ro]

    Fabricarea de ambalaje din carton ondulat (cutii, tăvi, etc) presupune un lanț de producțieintegrat, format din producătorii de hârtie, producătorii de carton ondulat și producătorii decontainere, dintre care, în Europa, majoritatea sunt IMM-uri. În prezent, containerele de cartonondulat sunt în mare parte realizate cu hârtie recuperată. Cea mai mare amenințare cu care seconfruntă lanțul de producție menționat este legat de lipsa de calitate și de disponibilitate a hârtieireciclate ca materie primă. Concret, una dintre cele mai importante proprietăți ale hârtiei deambalaj este rezistența mecanică, care depinde, în principal, de lungimea fibrelor din care estealcătuita hârtia. Aceste fibre sunt mai lungi în celuloza virgină (celuloza obţinută din lemn, adicănereciclată). Cu toate acestea, presiunea mare asupra cererii - precum și restricțiile economice șiecologice actuale referitoare la utilizarea lemnului ca materie primă - a condus la situația în caredoar o foarte mică cantitate de fibre naturale intră în lanțul de reciclare. Acest lucru înseamnă cărezistenţa fibrelor reciclate – si prin extindere – a hârtiilor – scade în mod constant, odată cuciclurile de reciclare aflate în desfăşurare. Suplimentar, hârtia reciclată prezintă o variabilitatefoarte mare, ceea ce constituie un obstacol atunci când vine vorba de a fabrica ambalaje cuproprietăţi omogene, cerute de către clienţi, la costuri fixe.Dificultatea de predicţie a proprietăților produselor din hârtie obţinute din surse eterogenepune mai multe limitări, care, din acest motiv, conduc la pierderi economice grave și numai ocaracterizare completă va permite mai buna lor folosire. Proiectul "RF-CORRUG - Controlulcalității materiilor prime din fibre recuperate pentru producția de carton ondulat", Cadrul NaționalStrategic de referinţă 2007-2013 Arhimede III, tratează această problemă tehnică comună aindustriei de carton ondulat. Concret, obiectivul principal al proiectului este de a sprijinicompetitivitatea companiilor producătoare de carton ondulat (în special IMM-uri), prin creareaunui instrument software bazat pe modele practice, care pot prezice proprietăţile sortimentului dehârtie de ambalaj, pornind de la proprietăţile fibrelor (calitative, cantitative, de structură) utilizateîn producția lor.Această lucrare prezintă informații referitoare la fibre (analiza cantitativă și calitativă,morfologia) și hârtiile de ambalaj (proprietățile fizice și mecanice) folosite în obţinereaambalajelor din carton ondulat. Au fost examinate diferite categorii de hârtii (miez şi capac),utilizate pentru producția de carton ondulat în Grecia. Principalele tehnici de analiză a fibrelor aufost: analiza masei fibroase, analiza morfologica a fibrei, microscopia optică, microscopiaelectronică de baleiaj (SEM). Suplimentar, a fost determinată rezistenţa la tracţiune (zero-spantensile test), pentru a măsura astfel rezistenţa medie a fibrei. Proprietăţile solicitate pentru hârtie au fost măsurate folosind testere şi standarderecunoscute pe plan internaţional. Informaţiile obţinute vor fi folosite pentru a dezvolta modelepredictive, bazate pe metode statistice avansate, pentru proprietăţile şi performanţele hârtiilor deambalaj, în funcţie de informaţiile furnizate de fibrele componente.

  • 7.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Ters, Thomas
    Vienna University of Technology, Austria.
    Fackler, Karin
    Vienna University of Technology, Austria.
    Cell wall properties of softwood deteriorated by fungi: combined chemical analyses, FT-IR spectroscopy, nanoindentation and micromechanical modelling2013Ingår i: Proceedings IRG Annual Meeting, Stockholm: The International Research Group on Wood Protection , 2013Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Mechanical properties of wood are determined by its inherent hierarchical microstructure, starting at the nanometer scale, where the elementary components cellulose, hemicelluloses, and lignin build up the wood cell wall material. Fungi cause degradation and decomposition of these components and, thus, alter the mechanical properties of wood. The aim of this study is to gain new insight into these relationships at the cell wall level, particularly at early stages of degradation, characterized by a mass loss of less than 10 %. Early detection of deterioration is essential during monitoring of timber structures as it may help avoiding subsequent larger scale damages. This contribution presents results of an ambitious experimental programme covering the determination of earlywood/latewood specific compositional data with consistent microstructural and micromechanical properties. Scots pine (Pinus sylvestris L.) sapwood was studied in reference condition and after degradation by brown rot (Gloeophyllum trabeum) and white rot (Trametes versicolor), respectively. Ultrastructural and compositional data were acquired by means of FT-IR spectroscopy and wet chemical analyses. Micro-structural features, such as the microfibril angle, were determined by X-ray diffraction. Mechanical properties of sound and degraded wood cell walls were determined using nanoindentation, yielding the (anisotropic) indentation modulus of the S2 cell wall layer and the cell corner middle lamella of Scots pine tracheids. Aiming at the identification of relationships between ultrastructural and micromechanical characteristics, two different approaches were followed. On the one hand, multivariate data analysis was applied. On the other hand, a multiscale micromechanical model was used to derive causal relationships between structure and (mechanical) function for deteriorated wood. Anisotropic indentation theory allows calculating model predictions for the indentation modulus of the S2 cell wall layer based on measured chemical compositions resulting from the degradation process. Comparing these predictions with the experimental results enables to test hypotheses on possible scenarios of wood cell wall deterioration during fungal attack. Identified relationships between ultrastructural, microstructural, and micromechanical characteristics will be discussed as well as the potential of micromechanical modelling in the analysis of fungal degradation strategies and their effect on the mechanical behaviour. 

  • 8.
    Trischler, Johann
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Hemmilä, Venla
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Challenges using annual plants as substitution for wood in particle-board production: Modification of reed canary grass2013Ingår i: Northern European Network for Wood Science and Engineering (WSE): Proceedings of the 9th meeting, September 11-12, 2013, Hannover, Germany / [ed] Brischke, Christian & Meyer, Lidia, Hannover: Leibniz Universität Hannover , 2013, 104-109 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Forecasts show that, already in 2020, the European consumption of wood and wood fibre raw material can be as large as Europe’s combined forest growth increment. An increasing proportion of the forest raw material is expected to be used as fuel for heating, as propellant fuel or to generate electricity. This means an increasingly tight competition for wood between the board industry and the energy-conversion industry and a need for the board industry to find new raw material sources.

     

    High productivity in the boreal regions makes reed canary grass interesting as a raw material for several applications where wood is today the main raw material. One possible application is in board manufacture, e.g. as a substitute for wood in the core of multi-layer particleboards. The properties of reed canary grass must, however be modified to meet the industrial standards for particleboard production and for the mechanical properties of the boards. Alternatively, different adhesives can be chosen.

    The purpose of this paper is to present some pre-treatments and adhesives suitable for use when reed canary grass is used as core material in industrial particleboard production.  An overview of different methods for pre-treatment and optional adhesives that can be used to increase the bonding properties of annual plants in the context of particleboard production is also presented.

     

    The bonding properties have been studied through mechanical tests and through light microscopy studies. Untreated and NaOH-pre-treated reed canary grass in combination with MUF, PVAc, Lignin, and PUR adhesives have been used in the tests.

    The results show that an adhesion suitable for particleboard production can be achieved with a NaOH-pre-treatment of the grass together with melamine urea formaldehyde (MUF), and especially PVAc and PUR adhesive. The adhesive system must, however, be optimized for industrial conditions.

  • 9.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Blomqvist, Lars
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Challenges using dielectric heating for THM processing of solid wood2013Ingår i: Evaluation, processing and predicting of THM treated wood behaviour by experimental and numerical methods / [ed] Carmen-Mihaela Popescu and Maria-Cristina Popescu, Iasi, Romania, 2013, 55-56 s.Konferensbidrag (Refereegranskat)
  • 10.
    Hedwall, Per‐Ola
    et al.
    Swedish University of Agricultural Sciences.
    Brunet, Jörg
    Swedish University of Agricultural Sciences.
    Nordin, Annika
    Swedish University of Agricultural Sciences.
    Bergh, Johan
    Swedish University of Agricultural Sciences.
    Changes in the abundance of keystone forest floor species in response to changes of forest structure2013Ingår i: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 24, nr 2, 296-306 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Question

    Does the abundance of keystone forest floor species change in response to changes in the forest structure?

    Location

    Sweden

    Methods

    We used data from the Swedish National Forest Inventory to investigate changes in the abundance of three common species, as well as the total abundance of all understorey vascular plants (the field layer) in forests in the boreal and temperate parts of Sweden. GLMs and GAMs were used to relate species abundance and temporal changes in abundances to forest structure and forest structural change.

    Results

    Productivity, measured as the site index, was the most important determinant of individual species' abundance. The volume of Picea abies, the density of tree stems and forest age were among the most important forest structural variables. We found that the dwarf shrubVaccinium myrtillus, the narrow-leaved grasses (mainly Avenella flexuosa) and the total field layer cover decreased in boreal Sweden from 1994 through 2010 and that these changes coincided with an increase in forest density and with a reduction in forest age.

    Conclusions

    Changes in Swedish forests to higher tree layer density and younger age appear to contribute significantly to current changes in forest floor vegetation. The use of more intensive thinning practices to reduce the total density of the forest and to increase the proportion of broad-leaved tree species and Pinus sylvestris would favour the forest floor species in this study. Moreover, increasing forest age (i.e. the length of rotation periods) might favour V. myrtillus in particular, for which the time since disturbance is important for the recovery of pre-disturbance abundance. However, increased thinning intensity and forest age will reduce the potential for wood production, implying a trade-off between production of wood and maintenance of well-developed forest floor vegetation.

  • 11.
    Stenudd, Stefan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Colour Response in Drying of Nordic Hardwoods2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Colour and appearance of hardwood are of great importance for the interiorand furniture industry. The widespread use of transparent surface treatmentand a fashion that prescribe light colour on many species, means that deviationfrom the ideal have considerable impact on the industrial operations. Kilndrying is generally regarded as the process that has the greatest impact on thecolour of Nordic hardwood species. The lack of satisfactory explanation modelsfor many types of discoloration, however, complicates the control of the dryingprocess.This thesis is an attempt to increase the knowledge of which factors thatcontrol the appearance of some commonly found discolorations associated withdrying of beech, birch and oak. The main focus is on convection drying but alsothe influence of timber storage, pre-steaming and press drying has beeninvestigated for individual species. The studies have been conducted ascomparative studies based on design of experiments in which the colour wasdetermined using a colorimeter.Results show that reddish and dark discoloration of beech and birch duringconvective drying is mainly dependent on the temperature and time of exposurewhen the local moisture content exceeds the fibre saturation point. Theconversion of naturally occurring substances in birch into coloured compoundsis not due to active precursors created at high moisture content levels duringthe subsequent drying at low moisture content levels. Interior grey stain inbeech is caused by slow initial drying at low temperatures. Log storage in coldwinter and spring climate does not cause discoloration in beech. Birch becomeslighter when press-dried at high temperatures, resulting in a colour comparableto that of traditionally kiln dried wood. Steaming of oak before kiln dryingreduce the presence of brown discoloration, a general darkening of the woodoccurs at temperatures above 50°C.

  • 12.
    Hu, Min
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Johansson, Marie
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Olsson, Anders
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Enquist, Bertil
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Comparison of local variation of modulus of elasticity determined on basis of scanned fiber angles and full strain field measurements2013Ingår i: The 18th International Nondestructive Testing and Evaluation of Wood Symposium, Madison, WI, USA, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Strength grading methods are normally based on relationships between one measured value of modulus of elasticity (MOE), regarded as being valid for the whole board, and bending strength. Studies have shown, however, that with a detailed knowledge of local variation of MOE within boards, a highter coefficient of determination (R2) with respect to bending strength can be obtained. Measurements of fiber angles from laser scanning has shown to be a powerful tool to establish MOE profile along boards in a speed that cooresponds to the production speed at a sawmill. The present study aims at investigating the accuracy of the local MOE profile determined on basis of fiber angles from laser scanning. The study was carried out on a board of Norway spruce of dimension 50 by 150 by 3,900 mm. First the fiber angles on all four surfaces were identified using a WoodEye scanner and on the basis of these measurements, a MOE profile was calculated. Thereafter, the board was subjected to a constant bending moment and suring loading an image correlation system, Aramis, was employed for detection of the strain field with high resolution along the whole board. This strain field was then used to estanlish a 'true' MOE profile along the board. The MOE profiles determined in two different ways were compared and they show a close compliance. However, some difference were found and these were used for calibration of the method for MOE determination on the basis of scanning results. The present research thus contributes further improvement of a newly suggested grading method.

  • 13.
    Rabasa, Sonia G
    et al.
    Spain.
    Granda, Elena
    Spain.
    Benavides, Raquel
    Spain.
    Kunstler, Georges
    France.
    Espelta, Josep M
    Spain.
    Ogaya, Romá
    Spain.
    Peñuelas, Josep
    Spain.
    Scherer‐Lorenzen, Michael
    Germany.
    Gil, Wojciech
    Poland.
    Grodzki, Wojciech
    Poland.
    Ambrozy, Slawomir
    Poland.
    Bergh, Johan
    SLU, Umeå.
    Hódar, José A.
    Spain.
    Zamora, Regino
    Spain.
    Valladares, Fernando
    Spain.
    Disparity in elevational shifts of European trees in response to recent climate warming2013Ingår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 19, nr 8, 2490-2499 s.Artikel i tidskrift (Refereegranskat)
  • 14.
    Lykidis, C
    et al.
    Institute of Mediterranean Forest Ecosystems and Forest Products Technology, National Agricultural Research Foundation, Greece.
    Mantanis, G
    Technological Educational Institution (TEI) of Thessaly, Greece.
    Adamopoulos, Stergios
    Technological Educational Institution (TEI) of Thessaly, Greece.
    Kalafata, K
    NanoPhos S.A., Greece.
    Arabatzis, I
    NanoPhos S.A., Greece.
    Effects of nano-sized zinc oxide and zinc borate impregnation on brown-rot resistance of black pine (Pinus nigra L.) wood2013Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, nr 4, 242-244 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, the brown rot resistance of black pine (Pinus nigra L.) wood, pressure-treated in an autoclave with nano-sized zinc borate and zinc oxide dispersions, was investigated. The two formulations based on zinc borate have given encouraging results, indicating fungicide effects of the metal nanoparticles onConiophora puteana. In specific, mean weight losses for P. nigra sapwood exposed to this fungus (one without and one with the addition of a binder) were negligible, that is 0.54% and 0.34%, respectively. On the contrary, the impregnation of pine wood with nano-sized zinc oxide resulted in minimal protection, i.e. 35.9% weight loss. Therefore, nano-sized zinc borate can be utilised in new formulations to impart resistance to wood against the brown rot C. puteana.

  • 15.
    Poudel, Bishnu Chandra
    et al.
    Mid Sweden University.
    Sathre, Roger
    Bergh, Johan
    Swedish University of Agricultural Sciences.
    Nordin, Annika
    Lundmark, Tomas
    Forest biomass production potential and its implications for total carbon balance2013Konferensbidrag (Refereegranskat)
  • 16.
    Poudel, Bishnu Chandra
    et al.
    Mid Sweden University.
    Lundmark, Tomas
    Swedish University of Agricultural Sciences.
    Bergh, Johan
    Swedish University of Agricultural Sciences.
    Nordin, Annika
    Swedish University of Agricultural Sciences.
    Forest management scenarios and their effects on ecosystem services: modelling results from Sweden.2013Konferensbidrag (Refereegranskat)
  • 17.
    Schauerte, Tobias
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Gustafsson, Åsa
    Linnéuniversitetet, Ekonomihögskolan (FEH), Institutionen för ekonomistyrning och logistik (ELO).
    From Customer Values to Production Requirements: Improving the Quality of Wooden Housing2013Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 9, nr 4, 780-787 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The industry of wooden single-family houses in Sweden faces several challenges; both with regards to production but also with regards to the market conditions. In order to avoid uncontrolled price increases of wooden single-family houses, an act regulating the cash contribution when purchasing a house has been introduced. This has led to an increased focus of the house price as well as on the individual producers to control its processes and thereby its costs. The purpose of this paper is to give an overview of existing research related to product and production developments related to the industry, identifying research gaps, and suggest research activities. This research has been carried out as a literature study focusing on these concepts. It concludes that existing research is fragmented and that the linkage between the consumer and the product is neglected as well as the holistic approach is missing in development activities. The authors propose that in order to study how the industry could come closer to their consumer markets and the aligned requirements as well as to facilitate product development, the Means-End Chain approach may be of use and that the approach could further be linked to Quality Function Deployment.

  • 18.
    Schauerte, Tobias
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Identifying Product Attributes for Quality Function Deployment: Consumer Perceptions in the Case of Wooden Multi-Storey Houses2013Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 9, nr 4, 773-779 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to bridge the gap between external consumer value and internal production quality, an understanding of consumers’ needs is vital. Consumers’ needs have to be translated through a firms’ internal value chain to improve production quality. The Means-End Chain approach elicits consumers’ needs in terms of product attributes, which further can be translated into engineering characteristics by using the House of Quality concept as the first step in Quality Function Deployment. Here, the relative importance of the attributes plays an important role for further processing. This paper’ aims at identifying product attributes and their relative importance, as an input into the House of Quality within Quality Function Deployment. This is done in the case of wooden multi-storey houses in Sweden, since there is a documented gap between the external consumer value and the internal production quality. Based on the Means-End Chain approach, the Extended Association Pattern Technique was used for a two stage study to elicit product attributes. Results from 34 interviews and 503 returned questionnaires revealed ten product attributes ranked by importance, to be further translated into engineering characteristics within Quality Function Deployment.

  • 19.
    Sint, KM
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Georg-August-University Göttingen, Germany ; Technological Educational Institute of Larissa, Greece.
    Koch, G
    Federal Research Institute of Rural Areas, Germany.
    Hapla, F
    Georg-August-University Göttingen, Germany.
    Militz, H
    Georg-August-University Göttingen, Germany.
    Impregnation of Bombax ceiba and Bombax insigne wood with a N-methylol melamine compound2013Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 47, nr 1, 43-58 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Methylated N-methylol melamine (NMM) is known for its ability to enhance physico-mechanical properties, anti-fungal ability, and hydrophobicity and was therefore used to impregnate two less used and non-durable wood species from Myanmar, Bombax ceiba and Bombax insigne. Solution uptake, weight percent gain and nitrogen content were increased by increasing melamine concentrations with B. ceiba always achieving higher values compared with B. insigne. According to the leaching results, a higher degree of condensation after curing as well as a better crosslinking of NMM could be obtained at higher temperatures. However, both curing temperatures used (90 and 120 °C) resulted in almost the same amount of nitrogen fixed in the cell wall. UV microspectrophotometry confirmed the penetration of the NMM into different morphological regions of wood tissues, which was again supported by the analysis of point measurement spectra of treated and untreated specimens.

  • 20.
    Nilsson, Jonaz
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Increased use of hardwood through light-weight constructions2013Ingår i: Proceeding of ISCHP2013 - International Scientific Conference on Hardwood Processing, October 7-9, Florence, Italy. / [ed] Berti, S. et al., Florence: CNR IVALSA , 2013, 291-296 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    The use of high density hardwood species for furniture and interior purposes can be limited because the weight. Keeping the weight low is important both from a user perspective and for logistic reasons in the manufacturing and distribution process. This work describes the construction and mechanical characteristics of a new type of light-weight panel in wood. The panel is a sandwich construction in three layers with hardwood as the surface layers. The surface layers are made of 6 mm thick solid beech and the core consists of solid pine wood in thicknesses of 24 or 96 mm cross-laminated to the surfaces. The total panel density was then 373 and 294 kg/m3 given a beech surface layer with a density of 725 kg/m3. The presented light-weight panel resulted in a 50-60 % decrease in the use of wood compared to a traditional edge-glued panel. Tests of the mechanical properties showed a bending stiffness in the longitudinal direction (of the core) of 2.9 kNm2 for a 36 mm thick panel and 221 kNm2 for a 108 mm thick panel. In the transverse direction, the corresponding values were 11 kNm2 and 88 kNm2. The overall results indicate that the light-weight panel presented shows promising technical and environmental properties and can thereby contribute to an increased use of hardwood species.

  • 21.
    Stendahl, Matti
    et al.
    Swedish University of Agricultural Sciences, Uppsala.
    Eliasson, Lars
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Integrated production of semi-finished components in sawmills, part II: Management of internal operations.2013Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 9, nr 1, 12-30 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, several Swedish sawmills have taken over production of components from customers in the furniture, joinery and house-manufacturing industries. The purpose of this study was to identify key factors in management of internal operations for sawmills with this strategy. A multiple case study design, based on face-to-face interviews with Swedish sawmill practitioners and on various forms of secondary data, produced comprehensive research information. Starting integrated production of components is a demanding strategy for sawmills. It requires deep knowledge about the customer and qualified skills in advanced further-processing of sawn wood. The complexity of quality management, production planning and cost calculation increases, and investments in processing equipment and customer relations reduce strategic flexibility. The diverging material flow complicates sawmills' possibilities to economize on scale, and they must instead economize on other factors, such as scope, combined operations and internal control. New tools for production follow-up and control, for production planning, for analysis of product profitability and for strategic partnership analysis are requested by practitioners. But, even if new analysis tools would facilitate better analysis and management of operations, the willingness and ability to innovate and learn among the personnel emerges as a key factor for success.

  • 22.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Luleå University of Technology.
    Integrated use of product data for improved wood material utilization in the furniture and joinery production2013Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 9, nr 4, 321-327 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quality communication from customer to supplier is crucial for the effectiveness of a value chain. In the forest products industry, a mutual understanding of quality requirements between customer and supplier in relation to material characteristics and production conditions is important if the material is to be utilized effectively.

     

    In the mechanical wood industry, hardwood has normally been quality graded manually. This has been a work-intensive operation and a problematic working environment. Automatic grading equipment based mainly on camera and laser technology is therefore gradually replacing the manual grading operation which relies on the human eye. The cross-cutting of sawn wood into shorter components with well-defined quality parameters is a process which needs to be automated. This makes it possible for the sawmill to redefine the quality grading process with e.g. more complex grading rules. To gain full benefits from the new technology, however, the grading process must be redefined in cooperation with the customers. There is also an expressed need for tools to communicate the quality of products produced by sawmills.

     

    In this study, three case studies were therefore performed where the communication of requirements between sawmills and customers was studied with regard to three different components delivered from two sawmills. In one sawmill, two products were studied; one intended for a furniture producer and one for a joinery producer. In the other sawmill, the studied product was intended for a producer of solid wood panels. The idea has been to study the need for product information expressed by both the customer and supplier through the automatic grading process and to utilise this equipment for data collection and visualisation.

     

    The requirements for a communication and data exchange tool have been derived. There is often an expressed need to measure how different raw materials affect the volume yield in a process and how different quality requirements affect the volume yield. Sharing this information between customer and supplier has been shown to yield a mutual understanding of how and why deviations occur. Visualisation possibilities are a prerequisite for a mutual understanding of quality conceptions.

  • 23.
    Nilsson, Daniel
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Lagring av flisad grot vid värmeverk: en jämförande studie mellan vinter och sommar förhållanden2013Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Företrädare för den energiomvandlande industrin upplever i vissa fall attdet är skillnader i den inmätta energimängden och den energimängd somlevereras ut till kund. Detta gäller även vid beaktande av verkningsgrad iförbränningsanläggningen.Syftet med studien har varit att identifiera och storleksbestämma deskillnader i energiinnehåll hos två stackar om vardera 1000 m3s flisad grotsom mättes in vid leverans, samt efter tre månaders lagring strax innanförbränning. Studien är genomförd under två tidsperioder den enarepresenterande vinter- och den andra sommarförhållande, dålagringsegenskaperna skiljer sig åt beroende på årstid.Medelfukthalten för groten som flisades under den frusna delen av åretbestämdes vid leverans till 41,5 % och var efter tre månaders lagring 42,8%. Substansförlusten noterades till 5,6 % och energiförlusten till 6,1 %.För den grot som flisades under sommarförhållanden bestämdesmedelfukthalten vid leverans till 32,2 % och efter tre månaders lagringhade medelfukthalten i stacken ökat till 44,6 %. Substansförlusternanoterades till 10,1 % och energiförlusten till 14,1 % under de tresommarmånaderna.Den grot som flisades under vinterförhållanden visade vid leverans på ettfuktigare material jämfört med den grot som flisades och levereades undersommarförhållanden. Däremot ökade fukthalten endast marginellt hosbränslet som flisades under vinterförhållandena medan fukthalten ökadeavsevärt under lagringen för bränslet som flisades undersommarförhållandena.Substansförlusterna i stacken med vinterflisad grot såväl som i stackenmed sommarflisad grot visade sig ligga väl i paritet med vad tidigare 

    studier visat med substansförluster på i storleksordningen 2 – 3 % permånad under de tre månader som studien pågick. Energiförlusterna vardäremot betydligt högre för den stack med sommarflisad grot vilket varväntat då både substansförlusterna och fukthaltsökningen var större.

  • 24.
    Hemmilä, Venla
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Trischler, Johann
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Lignin: an adhesive raw material of the future or waste of research energy?2013Ingår i: Northern European Network for Wood Science and Engineering (WSE): Proceedings of the 9th meeting, September 11-12, 2013, Hannover, Germany / [ed] Brischke, Christian & Meyer, Linda, Hannover: Leibniz Universität , 2013, 98-103 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Lignin has been studied as an adhesive for more than 100 years, but there are only a few industrial applications. The reason for the current interest is the high availability and low price of lignin. Lignin is the main by-product of paper pulping processes and is typically burned as fuel. Being the natural glue in plants and having a phenolic nature makes lignins an attractive replacement for wood adhesives.

     

    An adhesive system for wood composites consisting mainly of lignin has yet to be developed. Lignin has less reactive sites in the aromatic ring than phenols, and the steric effects caused by the macromolecular structure further hinder its reactivity. The low reactivity leads to slow curing and causes problems in applications where the curing speed is a critical parameter. Modifications such as phenolation, methylolation, and demethylation have been shown to have a positive impact on the reactivity of lignin.

     

    This paper presents properties of particle boards produced using unmodified and oxidized Kraft lignin adhesives. The paper also describes recent research relating to lignin as a base for wood adhesive and discusses the possibilities for future research.

     

    The boards produced with unmodified and modified lignin adhesives under equivalent pressing conditions performed poorly compared to the reference board made with standard UMF adhesive. Oxidation at the correct pH level improved the adhesion of the boards compared with those based on unmodified lignin. Efforts to produce an industrially viable lignin-based adhesive system will continue, and promising combinations of modifications and alternative hardeners are being studied.

  • 25.
    Fagerberg, Nils
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Lönsamhet i kontinuitetsskogsbruk i jämförelse med trakthyggesbruk: en litteraturöversikt2013Övrigt (Övrig (populärvetenskap, debatt, mm))
  • 26.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Micromechanical modeling of Common yew and Norway spruce2013Ingår i: Proceedings in Applied Mathematics and Mechanics: PAMM, ISSN 1617-7061, E-ISSN 1617-7061, Vol. 13, nr 1, 185-186 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this contribution, a micromechanical modeling approach in the framework of poromechanics is adopted to study structure-stiffness relations of two quite different species, namely spruce and yew, in detail. In particular, microstructural specialties of yew and spruce are assessed. A dominant influence of the cellulose content and its orientation on the stiffness of the cell wall is revealed, while on the macroscopic scale, density is found to be the governing microstructural characteristic for elastic properties.

  • 27.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Eberhardsteiner, Josef
    Vienna University of Technology, Austria.
    Micromechanical Modeling of Wood: Multiscale Modeling and Model Validation2013Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Due to its natural origin and its inherent heterogeneities, mechanical properties of wood are highlyanisotropic and show a broad variability, not only between different wood species, but also within a tree [1].Similar to other biological materials, the wood microstructure is well organized and hierarchically structuredfrom the annual rings visible to the naked eye down to the wood polymers cellulose, hemicellulose, andlignin at the nanometer-scale. The aim of the research conducted at the Institute for Mechanics of Materialsand Structures is a deeper understanding of the role of different hierarchical levels and their correspondingphysical and chemical characteristics in relation to mechanical properties of softwood and hardwood. This isachieved by means of micromechanical modeling and experimental analyses at various length scales.

    A micromechanical model provides the opportunity to predict poroelastic properties of softwood andhardwood tissues at different hierarchical levels from microstructural and compositional data [1,2]. Thehierarchical organization of wood is mathematically represented in a multiscale model. Effective poroelasticproperties are predicted by means of continuum micromechanical approaches (self-consistent method andMori-Tanaka method), the unit cell method, and laminate theory. These approaches are extended to accountfor water-induced eigenstresses within representative volume elements and repetitive unit cells, which aresubsequently upscaled to the macroscopic wood level.

    Verification of the micromechanical model for softwood and hardwood with a comprehensive experimentaldataset, shows that it suitably predicts elastic properties at different length scales under the assumption ofundrained conditions [3,4]. Moreover, Biot tensors, expressing how much of the cell wall water-induced porepressure is transferred to the boundary of an overall deformation-free representative volume element (RVE),and Biot moduli, expressing the porosity changes invoked by a pore pressure within such an RVE can bestudied at different length scales. Consequently, the relevance and the contribution of specificmicrostructural characteristics to the load transfer and the deformation characteristics in case of moisturechanges in wood can be studied. Besides the scientific interest in structure-function-relationships, theseinvestigations are motivated by the growing importance of wood as building material.

  • 28.
    Poudel, Bishnu Chandra
    et al.
    Mid Sweden University.
    Bergh, Johan
    Swedish University of Agricultural Sciences.
    Lundmark, Tomas
    Swedish University of Agricultural Sciences.
    Nordin, Annika
    Swedish University of Agricultural Sciences.
    Sathre, Roger
    Lawrence Berkeley National Laboratory, USA.
    Modelling forest management in Sweden: trade-offs between carbon benefit and biodiversity conservation.2013Konferensbidrag (Refereegranskat)
  • 29.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Moisture-induced distortion of laminated veneer products2013Ingår i: Proceedings of the 9th meeting of the Northern European network for wood science and engineering (WSE): September 11-12, 2013, Hannover, Germany / [ed] Christian Brischke & Linda Meyer, Hannover, Germany, 2013, 178-183 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Laminated veneer products consist of veneers bonded together with adhesive into a predetermined shape. Since wood is a hygroscopic material and also anisotropic by nature, laminated veneer products are especially shape-sensitive to changes in moisture content. A deviation from the intended shape is a problem for both the manufacturers and users of the final products and annually such deviations cause great economic losses in the manufacturing industry.

     

    To illustrate the influence of moisture on distortion and shape stability, studies have been performed in industrial conditions and in a laboratory environment. Veneers of beech and birch and a seat shell moulded from these veneers were used in the study. Distortion, i.e. spring-back, position and twist, has been determined directly after moulding and during subsequent moisture and drying cycles.

     

    The distortion follows more or less slavishly the changes in relative humidity around the product. The distortion is generally small directly after moulding but, after the laminates have been exposed to a variation in relative humidity, the distortion increases. Some of the problems of poor shape stability that may arise later in the bending process can be reduced if attention is paid to moisture content and fibre orientation already in the production of the veneer.

     

    To achieve good shape stability of laminated veneer products in practice, the following should be followed by the manufacture industry:

    • develop      cooperation with suppliers of veneer and set requirements of veneer with regard      to deviation of the fibre orientation, and require that the veneer be dried      and conditioned to a moisture content consistent with production,
    • control      incoming veneers with respect to fibre orientation and moisture content,
    • plan warehousing      of veneers and ensure adequate conditioning, and
    • consider      the orientation of the veneers and the species.
  • 30. Adamopoulos, Stergios
    et al.
    Voulgaridis, E
    Passialis, C
    Morphology and identification of fibre furnish components of papers used in the production of corrugated board2013Ingår i: Celuloza Si Harti, ISSN 1220-9848Artikel i tidskrift (Refereegranskat)
  • 31.
    Johansson, Jimmy
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Blom, Åsa
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Dvinskikh, Sergey
    KTH Royal Institute of Technology.
    NMR-measurements for determination of local moisture content of coated wood2013Ingår i: JCT Research, ISSN 1547-0091, E-ISSN 2168-8028, Vol. 10, nr 5, 601-607 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Local increased moisture content (MC) in wood constructions may result in different kinds of mechanical and, especially, biological degrading problems. Therefore, it is of great importance to control the MC of the material. However, there is at present no appropriate method for determining local MC in wood without destroying the product itself. Nondestructive measurements of local MC in wood is significant for the possibility of, for instance, monitoring the in situ MC in wood constructions over time, and thereby predicting potential problems. The nuclear magnetic resonance (NMR) technique has been shown to be valuable for the measurement of MC in wood. In this study, the possibility of utilizing this technique for local MC measurement in wood has been tested on wood samples exposed to water absorption for 72 h. The samples came from three different wood species treated with paint systems available on the market. In the wood samples an artificial “crack” had been created in the paint to introduce an area where the water could easily gain access to the wood. The results show the possibility of using the NMR technique for local MC measurements in wood. The measurement area, however, must be related to the properties of the material. In the case of wood, the measurement spot must be related to the early/latewood proportions. Further, a calibration of the NMR measurement must be made in relation to the expected density variations of the material.

  • 32.
    Bader, Thomas K.
    et al.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Poroelastic properties of hardwood at different length scales2013Ingår i: Poromechanics V: proceedings of the fifth Biot Conference on Poromechanics, July 10-12, 2013, Vienna, Austria / [ed] Christian Hellmich, Bernhard Pichler, Dietmar Adam, Reston: American Society of Civil Engineers (ASCE), 2013, 1830-1836 s.Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Hardwoods show a very complex, hierarchically organized microstructure. Slight structural differences at various length scales bring about a huge variety of hardwood species. This motivates the development of a micromechanical model for hardwood. Since differences in the microstructure of the material can be considered in the model, it offers the opportunity to explain the variability of mechanical properties of the whole class of hardwood. The micromechanical model is formulated in the framework of poroelasticity. In this contribution, poroelastic properties at different length scales of the material are discussed. Validation of the micromechanical model is based on an extensive experimental database covering elastic properties and microstructural characteristics of different temperate and tropical hardwood species. Exemplary parameter studies demonstrate the ability of the model to study the contribution of specific microstructural characteristics to the load transfer and the deformation characteristics of wood. 

  • 33.
    Voulgaridis, Elias
    et al.
    Aristotle University of Thessaloniki, Greece.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    Foti, Dafni
    Aristotle University of Thessaloniki, Greece.
    Voulgaridou, Eleni
    Aristotle University of Thessaloniki, Greece.
    Properties of gypsum bonded solid bricks manufactured with recovered wood and rubber2013Ingår i: Annual Meeting Prosylva Europe and 16th Panhellenic Forestry Conference , 6-9 October 2013, Thessaloniki, Greece, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Utilization of recovered wood fromparticleboard production residues and rubber from waste tires in the manufacture of solid bricks was investigated, using gypsum as bonding media. The manufacturing parameters were: small and large rubber and wood particles, different gypsum/wood/rubber ratios for each fraction (small, large), and different gypsum/water ratios. Cylindrical samples, produced by pouring the mixtures into cylindrical molds, were used for testing compressive strength, thermal conductivity and sound absorption according to standard methods.Compressive strength of all gypsum bonded wood and rubber samples was much lower than the controls, e.g. pure gypsum samples. It was found that the wood samplesand the larger fractions (both rubber and wood) were superior in strength than the rubber samples and small fractions, respectively. A maximum proportion25% of wood or rubber as well the use of reclaimed fibrous materials in the manufacture of samples would probably ensure an acceptable compressive strength. No differences were found among the wood/rubber typesfor thermal conductivity, while particle size and proportion of the materials had no effect. Samples with small wood and rubber particles at the lower proportion (25%) were similar in their sound absorption behaviour.

  • 34.
    Johansson, Marie
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Säll, Harald
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Lundqvist, Sven-Olof
    Innventia.
    Properties of materials from Birch – Variations and relationships: Part 2. Mechanical and physical properties2013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Birch regarded as Sweden’s third largest tree species. The two birch species, Silver- and Downy birch represents about 12% of total Swedish timber volume. For forestry, birch an important tree species which today mainly used for the manufacture of pulp and paper.

    The aim of this project was to describe mechanical and physical properties of birch. The properties that have been studied are stiffness, bending strength, shrinkage, spiral gran angle, density and microfibril angle in the cell wall and vessel cells, from different parts of the birch stems grown at different rates. The mapped properties have been compared also with those of other tree species, mainly spruce. The long term aim is to increase the knowledge of the birch wood properties to provide better predict their impact on products as well as provide a basis for better utilization of Swedish birch raw material and hopefully using birch as future structural timber.

    Three birch stands with different growth was chosen: Two stands where the birch growth has been different in a mixed forests stand of spruce and pine, and a fast growing stand with improved birch seedlings. Samples were taken from four different heights in the trees. The main thing that has been analyzed is the bending strength, modulus of elasticity, shrinkage coefficients in different directions and spiral grain. The mechanical tests are carried out on tines that are 20 x 20 x 300 mm and the fiber angle measurements were carried out on discs. These results have supplemented by the results of analyzes conducted with lnnventias SilviScan instruments that are able to recognize variations of year ring wood properties. Some of these are density, and microfibril angle, which is also included in this report.

    The results show that the wood from normal growth and fast growth improved birch receive equivalent wood properties. The results also show that birch wood properties are slightly better than that in Norway spruce.

    The material in this project was limited to only three stands and 11 sampled trees and therefore it can´t provide complete answers to the birch trees different wood properties. Limitations include genetic origin, growth rate, earlier silvicultural treatment and number of sample trees.

  • 35.
    Trischler, Johann
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Nilsson, Jonaz
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Reed canary grass as light-weight core in particleboards2013Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 9, nr 4, 469-476 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     Particle boards are an important material for furniture production. In this sector, two tasks have had priority during recent years: to reduce the weight of the panels and to reduce the formaldehyde emission. As the production methods have been more or less the same for decades, these tasks have to be tackled by reducing or replacing the raw material in the board production.

     

    In this study, the possibility of replacing wood with reed canary grass (Phalaris arundinacea L.) to obtain a light-weight particle board has been studied. The boards studied were three-layered with a core of wood/reed canary grass particles and a surface of 100 % wood particles. A protein-based adhesive was tested as an alternative to a UMF adhesive to reduce the formaldehyde emission. Different combinations of densities between 250 and 450 kg/m3 were included in the study and no additional treatments were made to the raw materials.

     

    The results showed poor mechanical and swelling properties of all the tested boards regardless of the design. The main explanation of the poor properties is the poor wetting of the reed canary grass surface by the adhesives. A pre-treatment of the reed canary grass particles with steam, lipase enzyme or alkali is suggested to increase the wettability.

  • 36.
    Gascón-Garrido, P
    et al.
    Georg-August-University Göttingen, Germany.
    Oliver-Villanueva, JV
    Polytechnic University of Valencia, Spain.
    Ibiza-Palacios, MS
    Furniture and Packaging Research Institute, Spain.
    Militz, H
    Georg-August-University Göttingen, Germany.
    Mai, C
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Georg-August-University Göttingen, Germany ; Technological Educational Institute of Larissa, Greece.
    Resistance of wood modified with different technologies against Mediterranean termites (Reticulitermes spp.)2013Ingår i: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 82, 13-16 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A laboratory no-choice test following the standard EN-117 was conducted to evaluate the efficacy of wood modified with different technologies against subterranean termites of the genus Reticulitermes spp. European beech modified with DMDHEU, acetylated radiata pine, and furfurylated Southern yellow pine were used for termite testing. Before the bioassay, half the number of the specimens (including controls) was subjected to an accelerated aging test according to EN-84. The specimens were exposed for 8 wk to the termites. Additionally, mass losses were measured. The results indicated that the feeding pressure was sufficient according to EN-117 for a valid test. Acetylated wood and DMDHEU-modified wood were classified as durable, showing excellent termite resistance. Furfurylated wood was resistant in the case of non-leached specimens; however, the leaching process led to a classification of non-durable. Thus, the new modification technologies open a real possibility of their use in the Mediterranean region as alternative preventive treatments against subterranean termites.

  • 37.
    Blomqvist, Lars
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Shape stability of laminated veneer products2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Formstabilitet hos formpressade fanerprodukter

    Lars Blomqvist

     

    Denna licentiatavhandling behandlar formstabilitet hos formpressade fanerprodukter.

    Formpressade fanerprodukter består av faner som sammanfogats med lim till en förutbestämd form. Metoden används i många sammanhang inom snickeriindustrin men under senare år är tillämpningen främst för tillverkning av möbler och inredning. Avvikelse från avsedd form hos de formpressade produkterna är ett stort problem för både tillverkare och kunder. Orsakerna till avvikelser i form kan relateras till både materialet och processen men också till hur produkten används. Det har i praktiken visat sig vara svårt att entydigt identifiera de viktigaste orsakerna till försämrad formstabilitet. I arbetet med denna avhandling har flera viktiga orsaker till försämrad formstabilitet kunnat fastställas och därmed har produkternas kvalitet kunnat förbättras och produktionsprocesserna effektiviseras.

    Avhandlingen presenterar några olika metoder för att kunna bestämma formstabiliteten. Metoderna är anpassade både för industriella och för mer forskningsrelaterade förhållanden. Studier har genomförts för att utvärdera inverkan av olika material- och processparametrar på formstabiliteten hos några utvalda formpressade produkter. De undersökta parametrarna var träslag (rödbok och björk), limsystem (biobaserade bindemedel och limsystem baserade på urea-formaldehyd), limspridning, klimat, jämviktsfuktkvot, fiberorintering hos faner samt orienteringen av faner i den specifika produkten.

    Resultaten visar entydigt att fanerens fiberorientering har en avgörande inverkan på formstabiliteten. Detta innebär att produkterna avsevärt kan avvika från den önskade formen, speciellt avseende skevning, om fanerens fiberorientering avviker på ett otillbörligt sätt vid sammanfogningen. Formfelen är vanligtvis små direkt efter sammanfogningen men kan öka avsevärt när produktens fuktkvot förändras, vilket är normalt vid användning.

    En osymmetrisk konstruktion med avseende på fuktkvoten hos faneren resulterade också i försämrad formstabilitet. Andra undersökta parametrar visade sig i jämförelse med fiberorientering och fukt ha en betydligt lägre inverkan på formstabiliteten. Träslaget björk visade sig dock vara mer formstabilt än rödbok.

    Orienteringen av faneren är också viktig när det gäller orienteringen av fram- respektive baksidan hos svarvade och knivskurna faner. Baksidan hos sådana faner har sprickor som en följd av skärprocessen vilka påverkar fanerets egenskaper. Om formstabilitet är det främsta målet bör faneren sammanfogas med baksidan orienterad åt samma håll genom hela konstruktionen, vilket normalt inte är fallet vid sammanfogningen. Detta kan dock leda till ökad förekomst av synliga sprickor i produktens ytor.

    För att producera formstabila formpressade fanerprodukter bör faneren vara väl konditionerade till önskad jämviktsfuktkvot och före sammanfogningen ska faneren sorteras med avseende på fiberorienteringen. Sammanläggningen är också viktig så att avvikelse i fiberorientering inte åstadkoms genom felaktig sammanläggning.

  • 38.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Shape stability of laminated veneer products: an experimental study of the influence on distortion of some material and process parameters2013Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, nr 3, 198-211 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laminated bending of veneers is a common used and important process for manufacture of components primarily for furniture and interior purposes. According to the use, such products are in general very sensitive to variations in the intended shape, i.e. distortion can be of great problem and more or less destroy the use of the final product. The most critical mode of distortion is twist, but also other changes in shape may be of interest to keep low. The causes to distortion of laminated bended veneer products can be of material (veneer, adhesive and the combination of these), design, processes and climate nature and there is a challenge to know which parameters which are of major importance for distortion, both directly after moulding and when the products are in use.

    In this study, the influence of type of UF-adhesive hardener, i.e. liquid or powder, water content of adhesive, adhesive distribution, variation of moisture content of glued veneers, and fibre orientation of veneers, on twist and position for a 3D-veneer construction (a chair seat shell) has been studied. Distortion, i.e. twist and position, has been determined directly after moulding and after moisture cycling. The moisture cycling was to simulate and accelerate conditions that the shells are subjected in use. The aim of the work is to study how the above mentioned material and process parameters influence the shape stability of the products.

    The results show that the climate, i.e. how a certain level of temperature and relative humidity influence the moisture content of the moulded product, has a clear impact on the distortion of the product in use. An increase in moisture content results in a significant increase in distortion and vice versa. The level to which the moulded products distort during climate variation can be controlled through controlling material, design and process parameter during moulding. Of the studied parameter mentioned above, a deviation in fibre orientation of the veneers in the moulded assembly is the most critical parameter to have under control to minimize distortion. The fibre deviation mainly results in an increase in twist. A high moisture content of a veneer vis-à-vis the rest of the veneers in the assembly before moulding, will result in increased position and twist of the moulded product in use. The difference of moisture content between veneers and the position of veneers with high moisture content in the assembly will influence the level of distortion. Other studied parameter also influences the distortion to a lesser extent and can in these cases be related to the moisture distribution in the mouldings.

  • 39.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Shape stability of laminated veneer products: How to decrease the negative effects of fibre deviation?2013Ingår i: Forest Products Society (FPS)  67th International Convention, Madison: Forest Products Society , 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    A shortcoming of the laminated bending process is that the products may become distorted after moulding and during use. Annually, significant financial losses have incurred in the furniture and interior design industries as a result of distorted products. In this study, we have examined the influence of deviation of fibre orientation of individual veneers on distortion of a moulded shell to find ways to improve shape stability of laminated veneer products.

    Ninety cross-laminated shells, consisting of 7 veneers of Birch (Betula pubescens Ehrh.) with a total thickness of 3.6 mm, were studied. The in-plane dimensions of the veneer were 400x660 mm. All the veneers were straight-grained, but to simulate deviation in fibre orientation some of the individual veneers were oriented 7 degrees relative to the main orientation of the other veneers in the laminate. Distortion was determined directly after moulding and after storage in a changing relative humidity.

    The results show the well-known fact that deviation of fibre orientation of the veneers in the laminate influences the shape stability of the product. The results from this study, however, also show how the placement of the abnormal veneers in the laminated veneer products influences the degree of distortions. From this basic knowledge some improvements for production of laminated veneer products were suggested.

  • 40.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Shape stability of THM-processed laminated veneer products glued with bio-based adhesive systems2013Ingår i: Evaluation, processing and predicting of THM treated wood behaviour by experimental and numerical methods / [ed] Carmen-Mihaela Popescu and Maria-Cristina Popescu, Iasi, Romania, 2013, 99-100 s.Konferensbidrag (Refereegranskat)
  • 41.
    Sandberg, Dick
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    State-of-the-art and tendencies in  THM wood processing.2013Ingår i: / [ed] Haller, P., Dresden: Technische Universität Dresden , 2013Konferensbidrag (Övrigt vetenskapligt)
  • 42.
    Kielmann, B
    et al.
    Georg-August-University Göttingen, Germany.
    Militz, H
    Georg-August-University Göttingen, Germany.
    Mai, C
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Strength changes in ash, beech and maple wood modified with a N-methylol melamine compound and a metal-complex dye2013Ingår i: Wood research, ISSN 1336-4561, Vol. 58, nr 3, 343-350 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ash, beech and maple wood was modified with aqueous solutions of methylated N-methylol melamine (NMM) and a metal-complex dye (BS) consisting of 10, 20, and 30 % NMM and 5 % BS. Static bending strength and stiffness, impact bending strength and hardness were examined to evaluate the suitability of modified wood for structural uses. The combined NMMBS modification resulted in significant higher dynamic (MOEdyn) and static (MOE) moduli of elasticity for all species. Beech and maple exhibited enhanced static bending strength (MOR), while that of ash was unchanged. The higher stiffness and strength of NMM-BS modified wood is attributed to its higher wood density and lower EMC and to the stiff character of NMM resin incorporated in the wood matrix. Impact bending strength decreased substantially after modification as a result of reduced pliability of treated wood. Brinell hardness significantly increased with the weight percent gain (WPG) due to modification, and, unlike the other properties, it was positively correlated with the WPG.

  • 43.
    Hemström, Kerstin
    et al.
    Mittuniversitetet.
    Mahapatra, Krushna
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Gustavsson, Leif
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Swedish private forest owners’ perceptions and intentions with respect to adopting exotic tree species2013Ingår i: European Journal of Forest Research, ISSN 1612-4669, E-ISSN 1612-4677, Vol. 132, nr 3, 433-444 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Swedish forest growth can be increased through intensive forestry practices, enabling an increased use of forest biomass for climate-change mitigation. However, the diffusion of such practices depends on the forest owners’ adoption of them. We study Swedish private forest owners’ perceptions and intentions with respect to increasing forest growth by adopting exotic tree species. The results of a mail-in questionnaire survey show that although a majority of forest owners desire increasing forest growth, most owners have only a basic understanding of exotic tree species and a smaller proportion is interested in adopting them. The intention to adopt exotics seems to depend on the perceived performance of the species with respect to the economic aspects of forest management rather than on environmental or recreational concerns. Whereas a knowledge gap among the private forest owners regarding how to increase forest growth is implied, forest owners with higher self-rated knowledge of forestry and exotics have stronger intentions to adopt such species.

  • 44.
    Wallertz, Kristina
    et al.
    SLU.
    Malmqvist, Cecilia
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    The effect of mechanical site preparation methods on the establishment of Norway spruce (Picea abies (L.) Karst.) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) in southern Sweden2013Ingår i: Forestry (London), ISSN 0015-752X, E-ISSN 1464-3626, Vol. 86, nr 1, 71-78 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to gain a deeper knowledge of the effects of mechanical site preparation on the survival and growth of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and Norway spruce (Picea abies (L.) Karst.) seedlings in southern Sweden. The experiment was conducted on a fresh clearcut at the Asa experimental forest (57° 10′ N). The effects of five different site preparation treatments were investigated: control, patch, mound, invert and mix. In each treatment, 40 seedlings of Norway spruce and 40 of Douglas fir were planted in each of four blocks. Site preparation had little or no effect on the survival and growth of Norway spruce: only a few seedlings died during the first 2 years. For Douglas fir, however, all site preparation treatments increased survival compared with the control, where mortality was high. The most intensive soil preparation treatment, mix, significantly increased root growth and total biomass. Pine weevils caused more severe damage to Douglas fir seedlings than to Norway spruce and targeted different locations in the two species, causing comparatively more damage to the leading shoots of Douglas fir seedlings.

  • 45.
    Nilsson, Bengt
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Blom, Åsa
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    The influence of two different handling methods on the moisture content and composition of logging residuals2013Ingår i: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 52, 34-42 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The most frequently used handling method in Sweden for the extraction of forest fuels is one in which logging residues are piled in harvester heaps to dry within the clear-cutting area before stacking into larger windrows. This handling method, however, requires multiple stages and the amount of handling involved results in a significant loss of biomass that could have been used for energy. This study compares two handling methods for the extraction of logging residues in stands dominated by Norway spruce. The traditional “dried-stacked” method was compared to the “fresh-stacked” method in which logging residues are collected simultaneously during normal logging operations and stacked in windrows at or near the roadside to dry. Determination of fraction composition and moisture content was carried out on the biomass provided to the energy-converting industry shortly after comminuting the logging residues. The results show that the fresh-stacked logging residues contained a higher amount of needles (8%), compared to 4% for the dried-stacked logging residues. However, the amount of needles was considered to be low in both handling methods. Both handling methods were proven to provide adequate drying with moisture content levels at approximately 36% for fresh-stacked and 31% for dried-stacked logging residues. These results indicate that weather and forest conditions have a greater impact on the moisture content than handling method. An acceptance of fresh-stacked logging residues, preferably connected to ash recycling, would afford the energy-converting industries the opportunity to use new technologies, reduce costs and extract a greater biomass total.

  • 46.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Al-Douhji, Ziad
    The Possibility of Manufacturing Medium Density Fiber board (MDF) from Cotton Seeds hulls as a Waste by-Product of Cotton Oil and Determination of its chemical Properties2013Ingår i: Minia Journal of Agricultural Research and Development, ISSN 1110-0257, Vol. 33, nr 1, 201-218 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This research has demonstrated the possibility of manufacturing models of Medium Density Fiber board (MDF)   from Cotton Seeds hulls as a Waste by-Product of Cotton with good Chemical Specifications comply with European specifications EN (DIN1999). Decrease in the average ability of models wood panels manufactured Medium Density Fiber board (MDF) of Cotton Seeds hulls to Formaldehyde release with the increasing Proportion of formaldehyde scavenger used, therefore the models containing 2% formaldehyde scavenger enjoy high-health quality. All models wood panels manufactured Medium Density Fiber board (MDF) of Cotton Seeds hulls characterized with good chemical specification (Formaldehyde release) Comply with European specifications EN (DIN1999) and enjoid a good health quality.  

  • 47.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Al-Douhji, Ziad
    The Possibility of Manufacturing Medium Density Fiber board (MDF) from Cotton Seeds hulls as a Waste by-Product of Cotton Oil and Determination of its mechanical Properties2013Ingår i: Minia Journal of Agricultural Research and Development, ISSN 1110-0257, Vol. 33, nr 1, 243-260 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     This research has demonstrated for the first time the possibility of manufacturing models of Medium Density Fiber board (MDF)   from Cotton Seeds hulls as a Waste by-Product of Cotton with good mechanical Specifications comply with European specifications EN (DIN1999). A steady increase in the rates of resistance of models wood panels manufactured Medium Density Fiber board (MDF) of cotton seeds hulls with Static Binding Strength of the increasing of Proportion of each the glue used, harder and formaldehyde scavenger used. All models wood panels manufactured Medium Density Fiber board (MDF) Seeds hulls, which glued with 14% characterized  with bad mechanical specification dont Comply with European standards for technical quality EN (DIN1999) and must be excluded.  All models wood panels manufactured Medium Density Fiber board (MDF) of Seeds hulls, which glued with 16% and 18% characterized with good mechanical Specifications Comply with European standards specifications, while the models glued with 18% characterized with soperior mechanical specifications for high technical quality, making it very good for the manufacture of furniture and coating halls. 

  • 48.
    Hameed, Mahmood
    et al.
    Damascus University, Syria.
    Al-Douhji, Ziad
    The Possibility of Manufacturing Medium Density Fiber board (MDF) from Cotton Seeds hulls as a Waste by-Product of Cotton Oil and Determination of its physical Properties2013Ingår i: Minia Journal of Agricultural Research and Development, ISSN 1110-0257, Vol. 33, nr 1, 219-242 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This research has demonstrated for the first time the possibility of manufacturing models of Medium Density Fiber board (MDF)   from Cotton Seeds hulls as a Waste by-Product of Cotton with good physical Specifications comply with European specifications EN (DIN1999).  Decrease in the average ability of models wood panels manufactured Medium Density Fiber board (MDF) of Seeds hulls to water absorption and the Cross-Swilling after 24h with the increasing Proportion of each the glue used, harder and formaldehyde scavenger used.  All models wood panels manufactured Medium Density Fiber board (MDF) Seeds hulls, which glued with 14% characterized  with bad physical specification dont Comply with European standards for technical quality EN (DIN1999) and must be excluded.  All models wood panels manufactured Medium Density Fiber board (MDF) of Seeds hulls, which glued with 16% and 18% characterized with good physical Specifications Comply with European standards specifications, while the models glued with 18% characterized with soperior physical specifications for high technical quality, making it very good for the manufacture of furniture and coating halls. 

  • 49.
    Routa, Johanna
    et al.
    Finnish Forest Research Institute, Joensuu, Finland.
    Kellomäki, Seppo
    University of Eastern Finland, Joensuu, Finland.
    Strandman, Harri
    University of Eastern Finland, Joensuu, Finland.
    Bergh, Johan
    Swedish University of Agricultural Sciences, Alnarp.
    Pulkkinen, Pertti
    Finnish Forest Research Institute, Läyliäinen, Finland.
    Peltola, Heli
    University of Eastern Finland, Joensuu, Finland.
    The timber and energy biomass potential of intensively managed cloned Norway spruce stands2013Ingår i: Global Change Biology Bioenergy, ISSN 1757-1693, E-ISSN 1757-1707, Vol. 5, nr 1, 43-52 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We used ecosystem model simulations to study the timber and energy biomass potential offered by intensively managed cloned Norway spruce stands. More specifically, we analysed how the use of cloned trees compared with non-cloned trees, together with thinning, nitrogen (N) fertilisation and rotation length (from 60 to 100 years), affects the annual mean production of timber (i.e., saw logs, pulpwood) and energy biomass (i.e., stumps and harvesting residuals in the final felling) and its economic profitability [annual mean of net present value (NPV) with a 2% interest rate]. Furthermore, we employed a life cycle analysis/emission calculation tool to assess the total net CO2emissions per unit of energy (kg CO2 MW h−1) produced based on energy biomass. We found that both the annual mean production of timber and the NPV increased substantially, regardless of the management regime, if cloned trees with an annual growth increase of up to 30% compared with non-cloned trees were used in regeneration. In general, the use of a short rotation with N fertilisation clearly increased the annual mean of the NPV. Consequently, the use of cloned trees also clearly increased the annual mean production of energy biomass and decreased the total net CO2 emissions per unit of energy produced based on energy biomass. However, the total annual net CO2emissions were the lowest if a long rotation was used with N fertilisation. To conclude, the use of cloned trees together with intensive management could potentially be highly beneficial for the cost-efficient and sustainable production of timber and energy biomass in an integrated way.

  • 50.
    Sandberg, Dick
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Haller, Peer
    Institute of Steel and Timber Construction, Technische Universität Dresden, Germany.
    Parviz, Navi
    Wood and Civil Engineering, Bern University of Applied Science, Biel, Switzerland.
    Thermo-hydro and thermo-hydro-mechanical wood processing: an opportunity for future environmentally friendly wood products2013Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 8, nr 1, 64-88 s.Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    This state-of-the art report presents the basic concepts of some of the thermo-hydro (TH) and thermo-hydro-mechanical (THM) wood processes that are in use today, i.e. heat treatment, compression of wood in the longitudinal or transverse direction, and wood welding. The reasons for the growing interest in TH and THM techniques are discussed and the development of the different concepts, from first ideas to current status, is briefly presented. The physical and chemical changes that occur in wood during TH and THM processing according to the latest research are also presented. Finally, developments that are close to or already have an industrial application are presented and the challenges for further development of the heat treatment, compression and wood welding processes are discussed.

    The TH processing of wood is based entirely on water and heat, and a THM process incorporates an additional mechanical force. The purpose of wood transformation by a TH or a THM process is to improve the intrinsic wood properties, to acquire a form and functionality desired by engineers without changing its eco-friendly characteristics or hindering its further use in the total material life cycle.

    Only a few of the recently developed techniques, e.g. wood welding and various densification applications, have been industrialized to any great extent. There are many reasons for this relatively low transfer of the research results to a full up-scaled industrial production. Some of them are related to unsolved problems at the laboratory level on small-size samples and others are related to the scaling-up processes in industry. Furthermore, the aging of heated wood leads to deterioration with time, in some cases there is an unpleasant odour, the strength of the wood decreases substantially and the wood becomes more brittle. These are new challenges which need to be resolved by the collaboration of researchers from the different scientific domains of academia, research institutes and industry.

12 1 - 50 av 56
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf