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Stokes, Agnes. "Wire water wood /." Online version of thesis, 1987. http://hdl.handle.net/1850/11466.
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Zhang, Wei. "Water overflow rage and bubble surface area flux in flotation." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86567.
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One of the most important factors that determines the concentrate grade in flotation is water recovery. Water recovery is influenced by frother through control of bubble size and possibly a frother-related chemical effect. A frother mass balance approach is presented for determining an equivalent water film thickness associated with bubble surface area flux exiting via the froth overflow to represent the chemistry effect.A closed loop mini flotation cell setup is used to achieve steady state in continuous tests. Four frothers are evaluated to reveal the dependence of water overflow velocity (JwO) on frother type and concentration. Using Total Organic Carbon analysis, frother partitioning between overflow and underflow is measured, showing a remarkable preferential distribution to the overflow at low frother dosage. From surface tension measurements the Gibbs excess adsorption density (Г) is estimated and used in the mass balance approach to estimate bubble surface area flux to overflow (SbO). Estimations from this approach are compared with bubble surface area flux into and on top of froth obtained from bubble size data using image analysis. A correlation is shown between JwO and SbO permitting an equivalent water film thickness carried by the bubble into the overflow (δO) to be estimated. The δO reflects the frother type: a stronger frother creates a larger δO and a weaker frother creates a smaller δO. Possible implications in flotation are discussed.
Dans les machines de flottation, le recouvrement d'eau est l'un des facteurs les plus importants dans la détermination de la teneur en minerai du concentré. Le recouvrement d'eau est influencé par l'agent moussant qui contrôle la taille des bulles et interagit possiblement d'un point de vue chimique. Afin de mettre en évidence le caractère chimique de cette interaction, une approche basée sur le bilan massique de l'agent moussant est présentée. Celle-ci vise plus précisément à déterminer l'épaisseur moyenne du film d'eau associé à l'aire de surface du flux de bulles empruntant comme voie de sortie la partie supérieure de la mousse.
Une cellule de mini flottation dotée d'un circuit en boucle est utilisée afin d'atteindre un d'état d'équilibre stable lors des tests en continu. Quatre agents moussants font l'objet d'études afin de comprendre la relation existant entre la vélocité du flux d'eau sortant (JwO) et le type et/ou la concentration d'agent moussant. Avec la méthode d'analyse du Carbone Organique Total, il est possible de mesurer la répartition de l'agent moussant entre la partie supérieure et la partie inferieure de la mousse. Lorsque la concentration en agent moussant est faible, on remarque que l'agent moussant se concentre préférentiellement dans la partie supérieure de la mousse. A partir de mesures de tension superficielle, l'excès de la densité d'adsorption de Gibbs (Г) est évalué et inclus dans le bilan massique afin d'estimer l'aire de surface du flux de bulle dans la partie supérieure de la mousse (SbO). Ces estimations sont comparées avec les aires de surface des flux de bulles au centre et dans la partie supérieure de la mousse, obtenues à l'aide de la technique d'analyse d'images. Une corrélation obtenue, entre JwO et (δO) permet d'estimer une épaisseur équivalente de film d'eau transporté par la bulle dans la partie supérieure. Des épaisseurs comparables de film d'eau transporté par la bulle dans la partie supérieure de la mousse δO sont obtenues. Le δO est caractéristique du type d'agent moussant : dans le cas d'un fort agent moussant, δO est épais alors que dans le cas d'un faible agent moussant, δO est fin. De possibles conséquences engendrées en matière de flottation font l'objet d'une discussion. fr
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Scheepers, Gerhardus C. "Liquid water flow and discolouration of wood during kiln drying /." Link to the online version, 2006. http://hdl.handle.net/10019/1189.
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Mji, N. (Ntuthuzelo). "Pressurised hot water extraction of wood : three wood species prior to pulping." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50423.
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Thesis (MSc)--Stellenbosch University, 2005.No english abstract available.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van warm water uitloging van houtspaanders by hoë temperature en onder hoë druk voor alkaliese verpulping te ondersoek. Warm water uitloging van houtspaanders onder druk voor alkaliese verpulping was baie belowend, aangesien dit ekstrakstowwe verwyder het wat andersins verteringschemikalieë sou opgebruik het en ook verbertede verpulpingstoestande meegebring het. Gedurende uitloging het die houtstruktuur verander agv die verwydering van die ekstrakstowwe. Dit het veroorsaak dat die houtstruktuur meer toeganglik geword het, en dit het gelei tot 'n verbeterde diffusie van die kookloog. Die versnelde kookloogdiffusie het 'n verbeterde en meer gelykmatige delignifikasie meegebring. Warm water uitloging by verhoogde druk is ondersoek vir drie houtsoorte nl. Eucalyptus grandis, Acacia mearnsii en Pinus patuia. 'n Twee-uur en 'n een-uur uitlogingstyd van die houtspaanders voorafgaande Kraft en soda-AQ verpulping is ondersoek.Vergelyk met 'n een-uur uitloging is daar gevind dat die twee-uur uitloging van die houtspaanders te drasties was, met 'n gevolg van 'n vermindering in pulpopbrengs, vesellengte en pulpsterkte. Die verlaging III pulpsterkte kon toegeskryf word aan polisaggariedafbreking. Die een-uur uitloging het 'n hoër opbrengs opgelewer as beide die kontrole (nie uitgeloogde houspaanders) en die twee-uur uitgeloogde houtspaanders. Die een-uur uitlogingsperiode het besonder goeie verpulpingsresultate vir die ekstrakstofryke Acacia mearnsii houtspaanders getoon, met 'n bykomstige verbetering in pulpsterkte eienskappe.
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Jalaludin, Zaihan. "The water vapour sorption behaviour of wood." Thesis, Edinburgh Napier University, 2012. http://researchrepository.napier.ac.uk/Output/4905.
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The water vapour sorption properties of several commercial tropical hardwoods and temperate softwood species as well as thermally modified wood and acetylated wood has been studied. A dynamic vapour sorption apparatus was used for this investigation to give data on the sorption isotherms under equilibrium conditions as well as sorption kinetic behaviour. Small differences in the sorption isotherms were found between the wood species, but modification resulted in substantial changes to the sorption isotherms. The sorption isotherms were analysed using the Hailwood-Horrobin model. Sorption kinetics behaviour was found to be accurately described using the parallel exponential kinetics (PEK) model. This model has only recently been applied to wood and this work represents a much more comprehensive study of the applicability of the model. Until now the favoured approach has been based upon Fickian models. The conventional interpretation of the PEK model relies upon the idea of different types of sorption sites, but his work has shown (partly based upon Hailwood-Horrobin analyses of the isotherms) that this interpretation is not applicable. Instead, an interpretation based upon relaxation limited kinetics has been adopted. These ideas are commonly employed in the polymer science literature, but have hardly been used in wood science. The model employed was that involving two Kelvin-Voigt elements in series, from which cell wall moduli and viscosities have been determined. The values of the moduli appear sensible, but the model is only tentative at this stage. The kinetic data has also been used to determine activation energies, entropies and Gibbs free energy of sorption. This is the first time that the entropy and Gibbs free energy of sorption have been studied. The purpose of this work was to understand the phenomenon of sorption hysteresis and in particular to examine if there was a link between sorption hysteresis and sorption kinetics.
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Jönsson, Ingrid. "Bio-based water/dirt repellant wood coating." Thesis, KTH, Fiber- och polymerteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298182.
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Syftet med detta examensarbete var att utveckla en helt bio-baserad vatten- och smutsavstötande ytbehandling för trä med ambitionen att ersätta en icke bio-baserad referens produkt på marknaden. Flera emulsioner med oljor och vaxer har framställts och analyserats utefter emulsionernas stabilitet och kvalitet. Flera av dessa emulsioners vattenabsorption, kontaktvinkel, pH värde vid ytan och åldrande i utomhusmiljö testades också efter att olika typer av trä behandlats med formuleringarna. En del av formuleringarna verkade ge liknande vattenabsorption som referensen på de olika typerna av trä med undantag för trä typ 4 där de bio-baserade formuleringarna presterade bättre än referensen. Vidare bildade även de bio-baserade formuleringarna en mindre gul och sträv yta jämfört med referensen och de genomgick dessutom en mindre fysisk förändring efter placering utomhus. Dock var stabiliteten för de bio-baserade emulsionerna sämre än för referensen. Dessutom resulterade de bio-baserade formuleringarna till en mindre pH sänkning på trä typ 3 med alkaliskt.The aim of this thesis project was to develop a fully bio-based water and dirt repellent wood coating with the ambition to replace the current non-bio-based reference product on the market. Several wax and oil emulsions were made and analyzed in terms of emulsion quality and stability. Several formulations were also tested on different types of wood in terms of water absorption, weathering, surface pH and contact angle. Some formulations seam to give similar water absorption as the reference, the not bio-based product and performs similar on different types of wood with an exception on Wood type 4 where the bio-based formulations performs better than the current reference product. Secondly the bio-based formulations form a less yellow and rough coating compared to the current reference product. According to the weathering test the bio-based formulations seams to perform better. However, the stability of the bio-based formulation is not as good as the current reference product. Also, the developed bio-based conceptual formulations exhibited limited pH lowering on Wood type 3 with alkaline pH.
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Salazar, Jose Amador Honorato. "The effect of water sorption on the creep of wood and chemically modified wood." Thesis, Bangor University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239924.
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Faure, Florent. "Étude du vieillissement hygrothermique et sous UV de composites préparés à partir de Polyéthylène Haute Densité et de différentes farines de fibres naturelles." Thesis, Lorient, 2019. http://www.theses.fr/2019LORIS536.
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Ce travail de recherche s’inscrit dans le cadre d’une collaboration entre l’IRDL et une entreprise majeure du bois composite européen. Les objectifs de ce projet sont d’estimer la durabilité des bois composites (WPC) destinés à être utilisés en environnement extérieur et d’étudier des voies d’améliorations possibles. Les mécanismes de vieillissement du bois composite sont souvent liés à l’action de l’eau, ainsi des essais d’absorption d’eau relativement longs sont utilisés pour s’assurer en première approximation de la bonne durabilité des mélanges. Un protocole d’absorption d’eau développé permet d’obtenir dans un délai relativement court les propriétés d’absorption d’eau (saturation en eau, cinétique de diffusion) des formulations fabriquées par extrusion. Le comportement pseudo-Fickien des composites est modélisé à partir de modèles mathématiques utilisant un coefficient défini comme la contrainte de gonflement. De nombreuses pistes sont étudiés pour essayer de déterminer les caractéristiques des constituants et la manière dont elles influencent l’absorption d’eau. Un protocole de vieillissement accéléré (UV, pluie, gel-dégel) est appliqué pour identifier les mécanismes de dégradation de composites absorbants différentes quantités d’eau. Enfin, des nouvelles farines végétales (colza, miscanthus, tournesol…) sont étudiées pour remplacer la farine de bois. Les propriétés des farines et des nouveaux composites sont comparées afin de déterminer l’apport de ces farines par rapport au boisThis research project is part of a partnership between the IRDL and a major European wood plastic composite company. The objectives of this project are to estimate the durability of wood plastic composites (WPC) intended for use in the outdoor environment and to study possible ways of their improvement. The ageing mechanisms of WPC are often linked to the action of water, so relatively long water absorption tests are used to ensure as a first approximation of the good durability of these mixtures. A water absorption protocol is developed in this thesis to improve these tests and allows to obtain in a relatively short time the water absorption properties of the tested WPC (water saturation, diffusion kinetics). The pseudo-Fickian behavior of composites is modelled from mathematical models using a coefficient defined as swelling stress. Hypotheses (porosity, mechanics...) are investigated to identify the characteristics of constituents which can influence water absorption of composites. An accelerated ageing protocol is applied to determine the degradation mechanisms of different composites. Finally, new natural flours (rapeseed, miscanthus, sunflower, etc.) are studied to substitute wood flour. The properties of new flours and composites are compared to wood flour and wood composite
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Paris, Jesse Loren. "Carboxymethylcellulose Acetate Butyrate Water-Dispersions as Renewable Wood Adhesives." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/34644.
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Two commercial carboxymethylcellulose acetate butyrate (CMCAB) polymers, high and low molecular weight (MW) forms, were analyzed in this study. High-solids water-borne dispersions of these polymers were studied as renewable wood adhesives. Neat polymer analyses revealed that the apart from MW, the CMCAB systems had different acid values, and that the high MW system was compromised with gel particle contaminants. Formulation of the polymer into water-dispersions was optimized for this study, and proved the â direct methodâ , in which all formulation components were mixed at once in a sealed vessel, was the most efficient preparation technique. Applying this method, 4 high-solids water dispersions were prepared and evaluated with viscometry, differential scanning calorimetry, dynamic mechanical analysis, light and fluorescence microscopy, and mode I fracture testing.
Thermal analyses showed that the polymer glass transition temperature significantly increased when bonded to wood. CMCAB dispersions produced fairly brittle adhesive-joints; however, it is believed toughness can likely be improved with further formulation optimization. Lastly, dispersion viscosity, film formation, adhesive penetration and joint-performance were all dependent on the formulation solvents, and moreover, these properties appeared to correlate with each other.Master of Science
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Shi, Jingbo. "Water sorption hysteresis and wood cell wall nanopore structure." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61782.
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The origin of sorption hysteresis in the wood-water system is still under debate. In this study, cell walls are considered as micro-mesoporous materials and capillary condensation in the entire hygroscopic region is proposed as an alternative sorption mechanism.
Initially, the pore connectivity was investigated by observing five experimentally generated hysteresis patterns at 25 and 40oC. Consistent patterns were found for the species-temperature combinations. Further, the satisfactory congruency and wiping-out properties indicate the dominance of independent cell wall pores. After this experimental phase, the geometric interpretations derived from the Preisach model, the mathematical form of the independent domain model, was used tο explain the observed hysteresis patterns. Additionally, a modification to the aforementioned model was suggested that involves a numerical implementation, which avoids the use of unknown parameters. The low prediction errors and well-maintained wiping-out property support the suitability of our approach.
In the next phase, grand canonical Monte Carlo (GCMC) technique was applied in a simplified wood-water system to simulate sorption isotherms and hysteresis at 25 and 40°C. In the simulation system, wood is represented by a cell wall model that is composed of solid substances and evenly distributed independent cylindrical nanopores with sizes in the range of 0.6 – 2.2nm. Two types of pore-wall compositions regarding polysaccharides and lignin have been considered. The hydroxyl groups are modeled as negative energy pits attached to walls whereas water is represented by the SPC/E model. Results demonstrated that hysteresis can be well explained by the existence of metastable states associated with capillary condensation and evaporation of water in cell wall pores. The alternative sorption mechanism driven by capillary condensation is also strongly supported by the simulation.
In the last phase, the cell wall pore size distributions in the hygroscopic range were explored for the three species from a “trial and error” calculation approach. This approach was indirectly examined by comparing derived volumetric strain of cell walls and the density of adsorbed water in the hygroscopic range with literature data. The qualitative agreement indicates the soundness of assumptions made on the cell wall swelling process and proposed calculation procedures.Forestry, Faculty of
Wood Science, Department of
Graduate
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Hartsfield, J. Carl (Jasper Carl). "Single Transponder Range Only Navigation Geometry (STRONG) applied to REMUS autonomous under water vehicles." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/39175.
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Thesis (S.M.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2005.Includes bibliographical references (leaves 124-125).
A detailed study was conducted to prove the concept of an iterative approach to single transponder navigation for REMUS Autonomous Underwater Vehicles (AUVs). Although the concept of navigation with one acoustic beacon is not new, the objective was to develop a computer algorithm that could eventually be integrated into the REMUS architecture. This approach uses a least squares fit routine coupled with restrictive geometry and simulated annealing vice Kalman filtering and state vectors. In addition, to provide maximum flexibility, the single transponder was located on a GPS equipped surface ship that was free to move instead of the more common single bottom mounted beacon. Using only a series of spread spectrum ranges logged with time stamp, REMUS standard vehicle data, and reasonable initial conditions, the position at a later time was derived with a figure of merit fit score. Initial investigation was conducted using a noise model developed to simulate the errors suspected with the REMUS sensor suite. Results of this effort were applied to a small at sea test in 3,300 meters with the REMUS 6000 deep water AUV. A more detailed test was executed in Buzzard's Bay, Massachusetts, in 20 meters of water with a REMUS 100 AUV focusing on navigation in a typical search box.
(cont.) While deep water data was too sparse to reveal conclusive results, the Buzzard's Bay work strongly supports the premise that an iterative algorithm can reliably integrate REMUS logged data and an accurate time sequence of ranges to provide position fixes through simple least squares fitting. Ten navigational legs up to 1500 meters in length showed that over 90% of the radial position error can be removed from an AUV's position estimate using the STRONG algorithm vice dead reckon navigation with a magnetic compass and Doppler Velocity Log alone (DVL).
by J. Carl Hartsfield, Jr.
S.M.
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Dyantyi, S. D. (Simphiwe David). "Fungal pretreatment of unextracted and pressurized hot water extracted Eucalyptus Grandis wood chips." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/21655.
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Thesis (MScFor)--University of Stellenbosch, 2007.ENGLISH ABSTRACT: Unextracted (control) and PHWe Eucalyptus grandis wood chips were pulped at 15% active alkali (AA) and 1% antraquinone (AQ). Another batch of wood chips were then inoculated with fungal co-cultures of Aspergillus flavipes and Pycnoporus sanguineus. FCCi wood chips were incubated for four weeks; one PHWe inoculated experimental treatment was incubated for three weeks. The full pulping cycle (160 min) was used to digest the experimental treatments with the exception of one lot of PHWe wood chips that were pulped for 150 minutes. A further experimental treatment of PHWe wood chips was cooked at a reduced AA charge of 14% and 1% AQ. Analysis of variance (ANOVA) of the data from all the experimental treatments was conducted and the differences within the experimental treatments were determined using Statistica (v7, 1984–2006). The F-value (Fischer distribution) and the p-value as well as a non-parametric test known as the Mann-Whitney procedure was tested at the 95% confidence limit. For a further enhancement of the 95% confidence limit the screened yield data was tested by the Bootstrap method. Scanning electron micrographs clearly demonstrated the changed structure and appearance of the chip cross-sectional area after the different pretreatments. Although the mean average results of all the screened pulp yields showed no significant statistical difference (p> 0.05), differences in screened yield of up to 2.5% were obtained. All the weighted means of the rejects showed a significant difference (p < 0.05). Other pulp properties like shive content, chemical consumption, Kappa number, handsheet brightness and strength tests showed mixed results i.e. rejected or accepted the hypothesis (p> or =or < 0.05). The hypothesis that the combined PHWE and FCCI of wood chips would further increase the pulp yield had to be rejected. It is however anticipated that the combination of PHWE with successive co-culture fungal pretreatment would be very beneficial in obtaining higher pulp yields for fully bleached chemical pulp. Further research would be required to test this assumption. This investigation confirmed the expected beneficial effects of combined PHWE and FCCI pretreatments of wood chips on the strength properties. In addition the combined treatment also improved the initial bonding strength potential of the unbeaten fibres.
AFRIKAANSE OPSOMMING: Onbehandelde en met onder druk, warm water uitgeloogde Eucalyptus grandis houtspaanders is respektiefwelik met 15% aktiewe alkali (AA) en 1% antrakinoon (AQ) verpulp. Hierdie is dan met swamkokulture van Aspergillus flavipes en Pycnoporus sanguineus inokuleer en respektiewelik vir drie en vier weke inkubeer. Onder druk uitgeloogde houtspaanders is ook vir 150 minute verpulp by 15% AA 1% AQ en by ‘n verminderde AA van 14%. Pulpevaluasies is uitgevoer op alle eksperimentele behandelinge. Alle onder druk uitgeloogde en met swamkokultuur inokuleerde houtspaanders het ‘n laer pulpopbrengs, uitskot, skilferinhoud, Kappanommer en ‘n hoër RAA en helderheid opgelewer in vergelyking met die vars houtspaanders. Die vars en warm water uitgeloogde houtspaanders het soortgelyke pulpopbrengs opgelewer. ‘n Variansieanalise (ANOVA) van die data van alle eskperimentele behandelings is uitgevoer gebruikmakende van Statistica (V7, 1984 – 2006). Die F-waarde (Fischer-verspreiding) an die p-waarde so wel as ‘n parametriese toets (Mann-Whitney prosedure) is getoets by ‘n 95% betroubaarheidsgrens. Vir ‘n verdere verhoging van die 95% betroubaarheidsgrens van die pulpopbrengs, is die beskikbare data weer getoets met die Bootstrap-metode. Alle gemiddelde pulpopbrengswaardes het geen beduidende statistiese verkil opgelewer nie (p>0.05), alhoewel verskille van tot 2.5% in pulpopbrengs verkry is. Alle gemiddelde uitskotwaardes het ‘n beduidende verskil getoon (p<0.05). Die ander pulpeienskappe soos skilferinhoud, verbruik aan chemikalieë, Kappagetal, handvel helderheid en sterktewaardes het gemengde resultate opgelewer maw verwerping of aanvaarding van die hipotese p> or =or < 0.05. Die hipotese dat die gekombineerde PHWE en FCCI van die houtspaanders die pulpopbrengs verder sou verhoog moes verwerp word. Daar word egter verwag dat die kombinasie van PHWE met opeenvolgende swamkokultuur behandeling baie voordelig sou wees op die pulpopbrengs van ‘n ten volle gebleikte chemiese pulp. Verdere navorsing is nodig om hierdie veronderstelling te toets. Die ondersoek het die verwagte woordelige effek van die gekombineerde PHWE en FCCI voorbehandelings van die houtspaanders op die papierstrkte-eienskappe bevestig. Bo en behalve dit, het die gekombineerde behandeling ook die aavanklikte bindsterkte potensiaal van die ongeklopte vessels verbeter.
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Skinner, Theodore Patrick William Cumming. "Dimensional stabilisation of waterlogged archaeological wood : an investigation of the water content of the cell wall of waterlogged archaeological wood and its replacement with water soluble compounds." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251601.
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Scheepers, G. C. "Liquid water flow and discolouration of wood during kiln drying." Thesis, Stellenbosch: University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1464.
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Thesis (PhD (Forest and Wood Science))--University of Stellenbosch, 2006.The discolouration of South African softwood during kiln drying can reduce the value of furniture grade lumber. Thermal discolouration of wood, as found due to heat treatment, produces a homogeneously browner colour in wood than is normally expected. This type of discolouration is attributed to reactions of the macromolecules present in wood and is found in both hard- and softwoods. Yellow stain and kiln brown stain can severely alter the colour of the outer few millimeters of a wooden board and is attributed to the reaction of water-soluble sugars and nitrogenous compounds, present in the wood sap, after deposition at the wood surface due to liquid or capillary water flow during drying. A discussion of the mechanism of discolouration due to yellow stain and kiln brown stain would be incomplete without a good understanding of the liquid flow of water during drying above fibre saturation point. This thesis brings the two concepts of liquid water flow and discolouration in context and is presented in four chapters: • an introduction motivating the aims of the investigation (Chapter 1); • a literature review of factors which may influence discolouration and liquid water flow during drying (Chapter 2); • original manuscripts describing the discolouration of South African softwood and liquid water flow in hard- and softwood (Chapter 3); and • a final conclusion that links up the results from the investigations (Chapter 4). The investigations into the occurrence of yellow stain and kiln brown stain showed that the intensity of these types of discolouration was influenced by geographical origin (and/or climate), tree species, planing depth of dried lumber, and kiln schedule parameters like dry- and wet bulb temperature and time. The characteristic discolouration pattern of yellow stain and kiln brown stain indicated that this stain type was related to the wetline phenomenon that is found during the liquid water flow phase of drying wet wood. Thermal discolouration, on the other hand, occurred homogeneously throughout the volume of lumber and is, therefore, not related to free water flow, but to chemical changes of the macromolecules in wood. The results of the liquid water flow investigations support the invasion percolation theory of drying that states that the largest meniscus will retract into a drying liquid-filled capillary network until it is not the largest meniscus anymore. Fluctuations in the rate of moisture loss from the cores of wood pieces above fibre saturation point were also found. The pattern of fluctuation differed appreciably between Betula verrucosa and Pinus radiata. In both cases, the start of the last phase in rate of moisture loss from the core coincided with a reduction in the cross-sectional area of the drying wood piece. This behaviour is explained by the hypothesis that distinct capillary size classes are emptied of free water, in order, from large to small. As smaller capillaries are emptied, the capillary forces become greater, to the point where the forces are great enough to cause permanent or temporary deformation of the remaining water-filled capillaries. Classification and regression tree analysis was a useful statistical technique to analyse a large multivariate dataset. The importance of kiln schedule temperatures and planing depth to control yellow stain and kiln brown stain was clearly pointed out by the technique, which can help to simplify the control of colour quality during the industrial processing of wood.
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Jacobson, Aaron. "Diffusion of Chemicals into Green Wood." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10516.
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Mass transport of chemicals into wood is important in kraft pulping. This thesis models small wood particles as cylinders and monitors how tritiated water and sulfide diffuse into the water-filled pores. Tritiated water diffusion is Fickian and diffuses completely into the water contained in the wood. Tortuosity values of the aspen and pine are tabulated. As particle size decreases, the tortuosity of the particles increases. As sulfide diffuses into wood, it is occluded from some water filled areas. Charge exclusion is a possible explanation for this. Sulfide and hydroxide transport into wood chips was displayed using indicators for each component. Pictures show sulfide ingress into the chip core faster, thus confirming the diffusion results. Fractionated sawdust was pulped to determine particle size effect on cooking and pulp properties.
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Stabenow, Joe H., Kristin N. Ulvestad, Logan Fitz, Vern Hardee, Greg Howard, Kris McClelland, Melissa A. Robbins, Wendy Woodward, and Fred A. Sundberg. "The Effects of Logging Burned Wood on Soil Erosion Rates." Arizona-Nevada Academy of Science, 2006. http://hdl.handle.net/10150/296641.
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Dean, Lesley Ruth. "The conservation and treatment of ancient waterlogged wood with polyalkylene glycols and the diffusion of water-borne polymers through wood." Thesis, University of Portsmouth, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316455.
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Baptista, Diogo. "Assessment of Water Penetration Resistance of Coatings on Wood by Droplet Dynamics Analysis." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/BaptistaD2005.pdf.
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Paredes, Heller Juan Jacobo. "The Influence of Hot Water Extraction on Physical and Mechanical Properties of OSB." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/ParedesJJ2009.pdf.
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Pollisco, Roy Roberto Arnoco 1962. "Management of pinyon-juniper woodlands for the sustained yield of wood and water." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/191940.
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The growing awareness on the importance of pinyon-juniper woodlands has greatly influenced the conduct of this study. The main objectives of this study were to develop stand, basal area, and stock tables, to relate tree growths to patterns of water yield, and to outline forest management strategies for the continuous and sustained production of wood and water. The tree inventory data were gathered using the point-sampling method in 1965 and 1986. Precipitation and runoff data were provided by the U.S. Department of Agriculture Forest Service. It was found that streamflow on the study watersheds had low values compared to commercial forest stands. Occasional extreme precipitation and runoff events adversely affected the watersheds by destroying vegetation and degrading soil characteristics. Based on the findings, it is suggested that single tree selection system is most appropriate for the study area.
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Shipek, D. Catlow, and Peter F. Ffolliott. "Water, Wood, and Wildlife Management of Emory Oak Coppice: A Preliminary Decision Matrix." Arizona-Nevada Academy of Science, 2003. http://hdl.handle.net/10150/296621.
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Källbom, Susanna. "Surface characterisation of thermally modified spruce wood and influence of water vapour sorption." Licentiate thesis, KTH, Byggnadsmaterial, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-172989.
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Today there is growing interest within the construction sector to increase the proportion of biobased building materials made from renewable resources. By-products or residuals from wood processing could in this case be valuable resources for manufacturing new types of biocomposites. An important research question related to wood-based biocomposites is how to characterise molecular interactions between the different components in the composite. The hygroscopic character of wood and its water sorption properties are also crucial. Thermal modification (or heat treatment) of wood results in a number of enhanced properties such as reduced hygroscopicity and improved dimensional stability as well as increased resistance to microbiological decay. In this thesis, surface characteristics of thermally modified wood components (often called wood fibres or particles) and influencing effects from moisture sorption have been analysed using a number of material characterisation techniques. The aim is to increase the understanding in how to design efficient material combinations for the use of such wood components in biocomposites. The specific objective was to study surface energy characteristics of thermally modified spruce (Picea abies Karst.) under influences of water vapour sorption. An effort was also made to establish a link between surface energy and surface chemical composition. The surface energy of both thermally modified and unmodified wood components were studied at different surface coverages using inverse gas chromatography (IGC), providing information about the heterogeneity of the surface energy. The water vapour sorption behaviour of the wood components was studied using the dynamic vapour sorption (DVS) method, and their surface chemical composition was studied by means of X-ray photoelectron spectroscopy (XPS). Additionally, the morphology of the wood components was studied with scanning electron microscopy (SEM). The IGC analysis indicated a more heterogeneous surface energy character of the thermally modified wood compared with the unmodified wood. An increase of the dispersive surface energy due to exposure to an increased relative humidity (RH) from 0% to 75% RH at 30 ˚C was also indicated for the modified samples. The DVS analysis indicated an increase in equilibrium moisture content (EMC) in adsorption due to the exposure to 75% RH. Furthermore, the XPS results indicated a decrease of extractable and a relative increase of non-extractable compounds due to the exposure, valid for both the modified and the unmodified wood. The property changes due to the increased RH condition and also due to the thermal modification are suggested to be related to alterations in the amount of accessible hydroxyl groups in the wood surface. Recommendations for future work and implications of the results could be related to knowledge-based tailoring of new compatible and durable material combinations, for example when using thermally modified wood components in new types of biocomposites for outdoor applications.Forskningsfinansiärer och strategiska forskningsprojekt:
Nils och Dorthi Troëdssons forskningsfond (Projektnr 793/12 Hydro-termo-mekanisk modifiering av trä).
KTH Royal Institute of Technology.
COST Action FP0904.
KK-Stiftelsen.
Stiftelsen för strategiskt forskning (SSF). QC 20150908
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Davoodi, Amir. "Modification of Water Uptake Capacity of Wood Using Colloidal Solution by Impregnation Technique." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41172.
Full textAbstract:
Hygroscopic properties are important characteristics of a material that is used in building
construction. Wood is an anisotropic, heterogeneous and hygroscopic material. Given the
cellular structure of wood as well as capillary action in the Lumina, the level of water uptake
in wood is significant.
Such amount of water uptake makes the wood susceptible to dimensional instabilities, causes
alterations in the mechanical properties, and potential for degradation of the material. Various
approaches have been investigated to modify the hydrophilic nature of lignocellulosic
materials, including surface modifications using silane treatments, acetylation, wax etc.
Although these surface modifications can decrease the rate of water uptake by the materials,
the amount of water uptake at saturation remains unchanged. In fact, the lumen diameter is so
small that the rise of liquid, even with a hydrophobic surface, can still occur. Therefore, the
only way to halt the water uptake driven by capillary action in lignocellulosic materials is to
apply a uniform cover on the material surface in addition to filling the lumen with dense
material.
In the current research project, the vascular structure of softwood (Spruce) is obstructed by
silica nanoparticles using the impregnation technique as one of the advanced methods to
reduce the water absorption capacity in wood. This process can form a thin film of
nanoparticles on solid objects with complex geometries. In addition, the technique can fill up
the cavities and voids of porous materials and prevent the capillary action inside the Lumina.
In this method, the wood specimen is dipped into the solution, silica 40 (wt. %) colloidal
solution. Then the solvent is evaporated which results in the formation of nanoparticles in
the form of thin films or particulates. The former may change the moisture absorption on the
surface and the later reduces the capillarity of the vascular system. This project aims to find
the optimal impregnation condition to minimize the water uptake capacity of wood in order to
increase wood physical and mechanical stabilities.
Three immersing times (i.e. short, medium, and long) were used to coat wooden samples with
the silica colloidal solution. The samples were conditioned in wet environments with specificiii
relative time and then their weight as percentage change were examined. To investigate the
capability of the method to obstruct the vascular structure of the wood samples, the
characteristic process was done in the next step by some common tests such as X-ray
Diffraction (XRD), Scanning Electron Microscope (SEM), Water Contact Angle (WCA), etc.
The results from the experiments show that dip-coating the wood samples with silica
nanoparticle colloidal solution had effect on the amount of water absorption, but significant
levels of reduction in water attraction was achieved with considering the other effective
parameters such as duration of each set, the number of sets that are conducted, and
impregnation in vacuumed condition. More research is needed to quantify the benefits of using
nanoparticle in these applications.
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Brooks, Christopher David. "Heteropolyacids of molybdenum and tungsten in water-borne wood preservatives and as oxidation catalysts in the oxidation of alkenes by hydrogen peroxide." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316590.
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Michalec, Jiri, and Sylvie Niklasova. "Water uptake of hardwoods." Thesis, Växjö University, School of Technology and Design, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-960.
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This study investigate water uptake in six different species of hardwood in tangential and radial section. Alder (Alnus glutinosa) and beech (Fagus sylvatika) represent semi-diffuse-porous hardwoods. Aspen (Popolus tremula) and birch (Betula pubescens) represent diffuse-porous group; oak (Quercus robur) and ash (Fraxinus excelsior) the ring-porous hardwoods. Spruce (Picea abies) was used as a reference sample.
Significantly higher water uptake was observed in the diffuse-porous and the semi-diffuse-porous group. Water uptake varied among the species, nevertheless tangential section was more permeable in general. Any impact of density or annual rings width on water uptake was observed. Correlation between ratio of earlywood and latewood and water uptake in dependence on hardwood group was found out. Ring-porous species had low rate of earlywood and low water uptake, whereas diffuse-porous and semi-diffuse-porous hardwoods had high rate of earlywood and high water uptake. Relation between water uptake and microstructure of wood was observed.
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Tasooji, Mohammad. "Novel Liquid extraction method for detecting Native-wood Formaldehyde." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/73511.
Full textAbstract:
New vigorous regulations have been established for decreasing the allowable formaldehyde emissions from nonstructural wood based composites. Two main sources of formaldehyde emission in non-structural wood based composites are adhesive and wood. Adhesives are quite well known and great efforts have been conducted to decrease their formaldehyde content; however formaldehyde emission from wood has received little attention and it is not completely understood. Wood-borne formaldehyde emission exists in a complex equilibrium in wood matrix. The reaction between formaldehyde and wood hydroxyl groups/water can hinder the complete formaldehyde extraction. In order to have a complete formaldehyde extraction, a stronger nucleophile than hydroxyl and water groups is needed.
In this study cross-linked poly (allylamine) (PAA) beads were synthesized and used as a strong nucleophile to extract all the biogenic and synthetic free-formaldehyde within the woody matrix of never-heated and heat-treated Virginia pines; the results were compared to simple water extraction. A new formaldehyde capturing device was also developed using a serum bottle.
Results showed that there was no advantage of using PAA beads over simple water extraction for extracting woody matrix free-formaldehyde. This means that simple water extraction can extract all the free-formaldehyde from the woody matrix. It was also found that thermal treatment resulted in generating more wood-borne formaldehyde. The other important finding was the new developed formaldehyde capturing device. The device was very promising for detecting wood-borne formaldehyde from very small pieces of wood (5-70 mg) and can be very useful in future studies.Master of Science
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Jonsson, Maria. "Wet storage of roundwood : effects on wood properties and treatment of run-off water /." Uppsala : Swedish University of Agricultural Sciences, 2004. http://diss-epsilon.slu.se/archive/00000645/.
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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2004.Thesis documentation sheet inserted. Appendix reprints four papers and manuscripts co-authored with others. Includes bibliographical references. Issued also electronically via World Wide Web in PDF format; online version lacks appendix.
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Ogilvie, Ticca Margaret Alison. "Water in archaeological wood : a critical appraisal of some diagnostic tools for degradation assessment." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/1528/.
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Yoshida, Kei. "Production of organic acids and methane from wood and chitin by supercritical water treatment." Kyoto University, 2009. http://hdl.handle.net/2433/126403.
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Kyoto University (京都大学)0048
新制・課程博士
博士(エネルギー科学)
甲第14844号
エネ博第198号
新制||エネ||45(附属図書館)
27250
UT51-2009-F486
京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻
(主査)教授 坂 志朗, 教授 東野 達, 准教授 河本 晴雄
学位規則第4条第1項該当
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Aigbomian, Eboziegbe Patrick. "Development of wood-crete building material." Thesis, Brunel University, 2013. http://bura.brunel.ac.uk/handle/2438/13445.
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Main concerns in the building industry includes the development of alternative building materials that reduces the amount of energy spent during manufacturing process and easier to work with. Wood-crete is a composite material developed in this study, made up of wood waste (sawdust), paper, tradical lime and water. Wood-crete is developed to provide an alternative material in construction solving problems associated with the delivery of low-cost housing across all income earners, reducing the amount of energy spent during manufacturing process of construction materials and the ease with which these construction materials are developed and solve issues related to waste management. This thesis presents the processing technologies, factors which affect the performance and properties of wood-crete. Wood-crete properties were found to be closely related to the composition of the constituent elements though compressive strength and modulus of elasticity were low when compared to other building materials like concrete and steel. In a bid to improve the strength of the developed wood-crete, the properties were investigated based on the modification of sawdust by hot water boiling and alkaline treatments which help to modify cellulose fibre surface to reduce the hydrophilic nature of sawdust thereby improving the sawdust-matrix bonding. It was found that the surface modification, processing of cellulosic fibril and the extraction of lignin and hemi-cellulosic compounds with alkali had an effect on the compressive strength of wood-crete, with treating sawdust with 4% NaOH at 140mins of boiling time achieving the highest compressive strength and boiling sawdust from 100mins to 140mins had a gradual increase in compressive strength but reduced at higher boiling time. Furthermore, treating sawdust with NaOH more than 4% weakened the individual wood particles thus leading to poor strength of wood-crete. Additionally, the properties of wood-crete were investigated based on the type of wood sawdust – hardwood (beech and oak) and softwood (pine and cedar). Apart from individual wood density having a significant effect on the density of wood-crete, other factors such as lignin, cellulose, hemicellulose contents including fibre length of individual wood species affect the strength properties of wood-crete. The compressive strength of wood-crete was closely related to the wood species, with highest compressive strength of 3.93MPa recorded for hardwood wood-crete compared to 1.37MPa and 0.26MPa of wood-crete from softwood and mixed wood respectively. Results from thermal conductivity tests on wood-crete also show that wood-crete blocks can be produced with good insulating properties for building construction. Addition of different types of paper fibres to reduce the density of wood-crete and improve the insulating properties of composite developed also had a dominant influence on both strength and thermal conductivity, reflecting its effect on the structure of composite and contribution of self strength of paper fibres. The addition of various percentages of waste paper (de-fibred) had a significant influence on the thermal conductivity of wood-crete with 75% addition of waste paper achieving a thermal conductivity value of 0.046W/mK performed with the TCi thermal conductivity analyser. Thermal conductivity results for wood-crete made from hardwood and softwood sawdust was closely related to the chemical composition of various wood species, with softwood wood-crete having about 20% lower thermal conductivity compared to hardwood wood-crete. The developed wood-crete was able to withstand impact load and considered, like hempcrete, most suitable for wall panelling or other non- and semi-structural applications with good thermal insulating properties. Findings of this study provides an alternative new material for the construction industry and an important background for achieving better strength of wood-crete, choosing what type of sawdust to be used for development of wood-crete and for directing a better use of this potential material with very small embodied energy and carbon negative.
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Nilsson, Josefin. "Permeability in surface treated Norway spruce samples- Effect of wood properties." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-22175.
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In Norway spruce there's a large natural variation in durability but knowledge about what is causing this variation is missing. In this thesis the focus were put into investigating how the water uptake ability was affected by the influence of heartwood versus sapwood and wood properties such as density and annual ring width. Liquid water permeability was checked trough a modified version of EN 927-5 and samples were also investigated trough the Mycologg Method. The wide grown wood with a coating system (a priming oil and alkyd or acrylate paint) absorbed less water than the narrow grown wood in the permeability test. The Mycologg test showed a clear difference between wide and narrow grown wood. Further research is necessary to examine the impact of wood properties when it comes to water uptake.
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Bannister, David A. "A pulsed NMR relaxation and diffusion study of water in treated and untreated waterlogged wood." Thesis, University of Nottingham, 1990. http://eprints.nottingham.ac.uk/11137/.
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Freezing curve, NMR relaxation data, and steady field gradient and pulsed field gradient experiments were conducted on samples of water-logged woods excavated from the Tudor warship, the Mary Rose and on similar samples impregnated with Polyethylene-Glycol solutions: the polymer used as a bulking agent to prevent decay. At least two distinguishable populations of water molecules are found in wood. Freezing curves indicate the presence of approximately 0.38 g/g of hydration water, close to that observed in fresh timbers. Relaxation measurements on pre-treated samples provides evidence of a very tightly bound fraction, present at water contents of below 0.14 g/g 0i hydration water, with a second population of hydration water being present up to 0.1.8 9/9. Above this value a third ‘free' population is observed. The relaxation decays in longitudinal and transverse direction have been analysed in terms of a sum of exponentials. These indicate the presence of two populations of water which do not correspond to populations observed in freezing curve analysis. Exchange mechanisms dominate the temperature dependency of the relaxation behaviour in pre-treated samples, which is similar to that observed in other fibrous materials such as meat. However, t he different components do not appear to correspond to the physical characteristics of the wood and the spin populations cannot be associated with a distribution between identifiable compartments within the system. In PEG impregnated samples the contribution to the signal from the polymer is not resolvable on the equipment used. Samples treated with PEGs for which the degree of polymerisation is greater than 1540 show a dependency of relaxation characteristics on the water content of the sample. At low water contents PEGs of low molecular weight impart a mobility to the "bound" water molecules which is not seen in untreated samples. . Belt diffusion coefficients for water molecules in wood are anisotropic, and are reduced from those observed in distilled water. This reduction is brought about because water molecules are both held in a hydration layer, and bounded by the cellular structure of the wood. In impregnated samples the diffusion rates are lowered by a factor of 10, though this is not reflected in the relaxation behaviour. The anisotropy is reduced, and proton exchange mechanisms are blocked.
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Turyk, Nancy B. "Nutrient and water budget modeling of the Petenwell Flowage Adams, Juneau, and Wood Counties Wisconsin /." Link to Abstract, 2002. http://epapers.uwsp.edu/abstracts/2002/Turyk.pdf.
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LeFrançois, Suzanne O'Neil 1980. "Ground penetrating radar characterization of wood piles and the water table in Back Bay, Boston." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/59653.
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Thesis (S.M. in Geosystems)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2003.Includes bibliographical references (p. 103-105).
Ground penetrating radar (GPR) surveys are performed to determine the depth to the water table and the tops of wood piles beneath a residential structure at 122 Beacon Street in Back Bay, Boston. The area of Boston known as the Back Bay was once a tidal estuary of the Charles River. During the latter half of the 19th century, the Back Bay was filled to create room for the city's expanding population. Most of the structures built in the Back Bay during this period were residential buildings supported by untreated wood pile foundations. Submerged beneath the water table, untreated wood piles maintain their structural integrity indefinitely. However, recent groundwater fluctuations throughout the Back Bay have exposed the tops of some of the piles, causing the exposed areas to rot. Rotted wood piles weaken a structure's foundation and often result in differential settlement or cracking in walls or foundations. The current method of investigating suspected pile failure is to excavate a foundation and to physically inspect the piles, noting the elevation of the water table. In many cases, foundations may be stabilized by underpinning: replacing rotted wood piles with steel beams or concrete plugs often at great cost to the owner of the building. The research presented in this thesis investigates the usefulness of GPR in determining the proximity of the tops of wood piles relative to the water table. Two different types of radar surveys were used in an attempt to estimate the depth to the water table and the tops of the piles. Data collected from several radar surveys is interpreted and compared with ground truth derived from historical references, water level data from monitoring wells, observations from recent excavations, and the results of a resistivity survey. The results of this study indicate that modifications of this technique may allow more definite interpretation of wood pile foundations than traditional GPR surveys can provide in this type of environment.
by Suzanne O'Neil LeFrançois.
S.M.in Geosystems
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Aboubi, Fadoua. "A cost effective and environmentally friendly stormwater treatment method : The use of wood fly ash and H2O2." Thesis, Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-12204.
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This current study is a lab-scale investigation focused on the treatment of stormwater runoff generated in wood-storage areas. The main target constituents of the proposed treatment were: metals (Cu, Cd, Co, V, Pb, Zn, Ni, Cr, Fe, As), COD, TOC, Phenols, and color. The method implemented for this project follows the main concept of using low-cost and environmentally friendly technologies and had as main steps the use of a by-product of wood-based industries - wood fly ashes as sorbents - followed by oxidation with H2O2 (Hydrogen Peroxide). The results obtained during this investigation were vey promising since satisfactory removal % was achieved. Removal rates of 98.5%, 86%, 89.6%, 79.6% were achieved for color, chemical oxygen demand (COD), total organic carbon (TOC) and phenols respectively. Furthermore a decrease in metals concentrations was also observed with the exception of chromium. The study showed that for 300 ml storm water, optimum conditions were with 7g wood fly ash, 5 hours time reaction, pH≈11.46 and 150 μl of a 30% H2O2 solution in a room temperature. To conclude it can be stated that the use of a by-product from wood industry to treat contaminated water from the same sector, following the concept of a closed-loop system, is promising and possible. However further studies need to be conducted in order to evaluate such system in scaled-up conditions.
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Walsh, Frances Luella. "An Isotopic Study of Fiber-Water Interactions." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/13973.
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A new technique for measuring the water content of fiber is presented. Tritiated water is added to a pulp/water suspension whereupon the tritium partitions between the bulk water and the pulp. Through this technique a fiber:water partition coefficient is developed, Kpw. This thesis will cover the development of the Kpw procedure and three different case studies.
The first study involves comparing Kpw to traditional methods of fiber water content. The procedure provides a value of ten percent for the tightly bound water content of unrefined hardwood or softwood kraft fiber, either bleached or unbleached. If this water is assumed to cover the fiber surface as a monolayer, then an estimate of the wet surface area of fiber can be obtained. This estimate compares well to independent measurements of surface area.
Kpw has also been found to be valuable in furthering the understanding of refining. Based on the study, it is proposed that refining occurs in three discrete stages. First, refining removes the primary cell wall and S1 layer while beginning to swell the S2 layer. Next, internal delamination occurs within the S2 layer. Finally, fiber destruction occurs at high refining levels. By using Kpw, the three stages of refining are clearly recognized.
Lastly, Kpw is used to study the effect of hornification on bleached softwood kraft fiber. The recycling effects at three refining levels were characterized by Kpw and followed closely the findings of the refining study. At low and high refining levels, the impact of recycling was minimal according to Kpw results, but at 400 mL csf the impact of recycling was much more pronounced. This could be attributed to the closing of internal delaminations within the fiber.
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Tekleyohannes, Anteneh Tesfaye. "Unified and heterogeneous modeling of water vapour sorption in Douglas-fir wood with artificial neural networks." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/23032.
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The objective of this study was firstly to investigate and understand sorption properties of earlywood, latewood, annual rings and gross wood. Secondly, to develop a heterogeneous sorption model for earlywood, latewood and annual rings by taking into consideration unified complex interactions of anatomy, chemical composition and thermodynamic parameters. Thirdly, to upscale the annual ring level model to gross wood by applying artificial neural networks (ANNs) modeling tools using dimensionally reduced inputs through dimensional analysis and genetic algorithms.
Four novel physical models, namely, dynamical two-level systems (TLS) model of annual rings, sorption kinetics, sorption isotherms and TLS model of physical properties and chemical composition were derived and successfully validated using experimental data of Douglas-fir. The annual ring’s TLS model was capable to generate novel physical quantities, namely, golden ring volume (GRV) and golden ring cube (GRC) to which the sorption properties are very sensitive, according to the validation tests. A new heterogeneity test criterion (HTC) was also derived. Validations of the TLS sorption models revealed new evidence showing a transient nature of sorption hysteresis in which boundary sorption isotherms asymptotically converged to a single isotherm at large time limit. A novel method for the computation of internal surface area of wood was also validated using the TLS model of sorption isotherms. The fibre saturation point prediction of the model was also found to agree well with earlier reports. The TLS model of physical properties and chemical composition was able to reveal the self-organization in Douglas-fir that gives rise to allometric scaling. The TLS modeling revealed existence of self-organizing criticality (SOC) in Douglas-fir and demonstrated mechanisms by which it is generated.
Ten categories of unified ANNs Douglas-fir sorption models that predict equilibrium moisture content, diffusion and surface emission coefficients were successfully developed and validated. The network models predict sorption properties of Douglas-fir using thermodynamic variables and parameters generated by the four TLS models from chemical composition and physical properties of annual rings. The findings of this study contribute to the creation of a decision support system that would allow predicting wood properties and processing characteristics based on chemical and structural attributes.
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Grotkopp, Ingo. "Influence of water on the mechanical properties of wood investigated using X-ray and neutron scattering." [S.l.] : [s.n.], 2006. http://e-diss.uni-kiel.de/diss_1838/d1838.pdf.
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Ekstedt, Jan. "Studies on the barrier properties of exterior wood coatings." Doctoral thesis, KTH, Civil and Architectural Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3453.
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Coatings for exterior wood have two basic functions. One isto give an aesthetically acceptable surface appearance andcolour. The other is to provide protection against wooddegradation by microbiological or physical attack. Theseprotective properties, often called the barrier properties,play an important role in the selection of proper material forsupreme durability. The assessment of these barrier propertiesis of great importance. Within the CEN Technical Committee 139,Working Group 2, Coatings for exterior wood test methods andperformance specifications have been established. Forassessment of water protection efficiency a standard testprocedure, EN 927-5, has been launched. The present work hasfocused on its applicability in assessing water protectionefficiency in relation to the degradation of coatings duringexposure.
Assessments according to EN 927-5 is shown to givesignificant differences in water absorption values fordifferent types of coatings on wood. The proposed performancespecifications in ENV 927 - 2 for the water absorption valuesfor coatings to be used in different constructions seem to beset at acceptable levels. It has been shown that there is agood correlation between the level of water absorption andpractical experience of the performance of paints inScandinavia. However, it has also been shown that thecombination of a standard procedure for water absorptionmeasurement and an artificial weathering procedure gives moreinformation regarding expected durability and longtermperformance than a single measurement of water absorption onfresh, unweathered coated wood. A combination of waterabsorption measurement and artificial weathering could become auseful tool in product development as well as in benchmarking.Together with statistical tools, such as reliability-basedservice life prediction methodologies for predicting theservice life of coating systems a reduction in testing timesmay be achieved.
Surface-active substances in coatings have a negative effecton the coatings ability to prevent water ingress, which mostprobably is due to the hydrophilic character of thesesubstances. The presence of these substances, which are commonin waterborne coatings, alters the moisture sorptioncharacteristics of wood. Considering that these substancesoccur in waterborne coatings, may be mobilised during and afterfilm formation and accumulate at the coating/substrateinterface, there is a great probability that these substanceschange the moisture sorption characteristics of the woodsubstrate in an unfavourable way and create unexpected dynamicmoisture conditions at the coating/wood interface.
Computerized tomography has been found to be a valuable,non-destructive tool for visualising the spatial moisturedistribution of water and moisture in coated wood panels. Themethod is suitable for recurrent testing of a specimen exposedto a series of processes of wetting, drying. This thesis showsthat high moisture contents occur locally at and around cracks.In these areas there is an increased risk of internal tensionand stress resulting in crack initiation and propagation andthat high moisture contents may occur in the first fewmillimetres under waterborne coatings despite intact coatingfilms. Even with good barrier properties of the coating,moisture may accumulate by water-vapour absorption in air gapsbehind the cladding thus causing favourable conditions formicrobiological colonization.
The work that has been carried out regarding assessment ofthe water protection efficiency shows promising resultsregarding the possibility to use reliability-based service lifeprediction methodology for the assessment. The aim of futurework will be to establish more reliable techniques andprotocols for assessing service life expectancy and durability,especially for waterborne coatings with special focus ontendencies to early failure and robustness of the coatingsystems.
Keywords:Coatings, surfactants, water absorption value,EN 927, paint, additives, moisture dynamics, absorption,desorption, artificial weathering, artificial exposure,computerized tomography, MRI.
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Mangum, Lauren Heard. "Treatment of Timtek process water by co-composting and aqueous phytoremediation." Master's thesis, Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-04022009-101708.
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Zhu, Xiangwei. "Unfolding, crosslinking and co-polymerization of Camelina protein and its use as wood adhesives." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35420.
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Doctor of PhilosophyDepartment of Grain Science and Industry
X. Susan Sun
Oilseed protein is a promising renewable source to be used as the replacement of petroleum-based materials for adhesion purpose, and it has drawn increasing attention since soy-based adhesives were developed for wood glues. However, soy protein comprises a portion of humans’ diets, thereby creating competition between utilization of soy protein for protein-based products or human food. Therefore, alternative bio-resources must be discovered. Proteins from camelina sativa provide such potential. Similar to other protein-based polymers, low mechanical strength and poor water resistance are the major drawbacks limiting camelina protein’s further applications. In this research, camelina protein (CP) was modified by unfolding, crosslinking, and co-polymerization treatment for improved flow-ability, adhesion properties and water resistance, which facilitates the industrialization of camelina as an alternative to soy-based adhesives. The physicochemical properties and microstructures of CP were also investigated. To increase the reactivity of CP adhesive, the first step is to denature the folded structure of native proteins. Camelina protein was extracted from defatted camelina meal through alkali solubilization and acid precipitation and modified with varying amount of NaHSO₃ (0-12% of the protein dry base) and Gdm.Cl (0-250% of the protein dry base). NaHSO₃ treatment broke the disulfide bonds of the CP and thus increased its free sulfhydryl content and surface hydrophobicity. As NaHSO₃ concentration increased, the viscosity, elastic modulus (G') and water resistant of NaHSO₃-modified camelina protein (SMCP) dispersion decreased, and the protein became hydrophobic. Gdm.Cl treatment broke the CPI’s hydrogen bonds but decreased their surface hydrophobicity. Similarly, viscosity, G', and water resistant of Gdm.Cl-modified camelina protein (GMCP) dispersions decreased as Gdm.Cl increased and protein became to aggregate. The reducing effect of NaHSO₃ was more obvious than Gdm.Cl to disrupt CPI’s intermolecular protein interaction but less obvious than Gdm.Cl to reduce the viscosity and water resistant. To further increase the CP’s water resistance, a coupling agent, Ethyl-3-(3-dimethyl-aminopropyl-1-carbodiimide) (EDC), was applied to stabilize the protein structure by crosslinking the free carboxyl groups and amino groups. The cross-linked CP exhibited increased molecular weight and particle size. Microstructures of modified CP also became rigid and condensed. Accordingly, CP’s increased intermolecular protein interaction resulted in its higher elastic modulus, viscosity and water resistance. The ultrasound pretreatment further increased the crosslink degree of CP, which resulted in protein’s increased aggregation behaviors and compact micro-structures. Consequently, the elastic modulus, viscosity, and water resistance of CP increased accordingly. Copolymerization with hydrophobic enhancers was also an effective method to improve CP’s water resistance. In this study, kraft lignin was oxidized by H₂O₂ and then copolymerized with CP as wood adhesives, which exhibited increased wet strength. In the presence of ultrasound irradiation, the H₂O₂-depolymerized kraft lignin exhibited reduced particle size, thermal stability and increased content of hydroxyl groups. Fluorescence spectroscopy analysis revealed that after coupling with pristine or de-polymerized lignin, CP exhibited increased hydrophobicity due to lignin’s increased reactivity with camelina protein. Accordingly, the water resistance of CP-based adhesives improved. In the optimized condition, when CP was copolymerized with ultrasound-induced oxidized lignin, it had increased wet shear adhesion strength from 0.28 MPa to 1.43 MPa, with wood panels passing the three-cycle water soaking test.
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Levin, Joshua Aaron. "Western Empire: the deep water wreck of a mid-nineteenth century wooden sailing ship." Texas A&M University, 2003. http://hdl.handle.net/1969.1/3928.
Full textAbstract:
This study of Western Empire is split into two distinct parts: (1) historical research of the
life of the vessel, relying on primary documents; and (2) analysis of the deep water
survey data. The first part concentrates on the historical documents that constitute the
history of Western Empire. The second part begins with a review of the tools and
procedures used in performing the deep water survey. An analysis of the information
that can be taken from such a study will follow, and it concludes with suggestions for
remotely operated vehicle operators when performing an on-the-fly survey of
shipwrecks in deep water. The official ship logs, crew agreements, and contemporary
newspaper articles are used to recreate the life of Western Empire and shed light on a
period in which wooden sailing ships were being displaced by iron ships and steam
power.
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Koestner, Peter E., Karen Koestner, Daniel G. Neary, and Carl C. Trettin. "An Overview of the Sierra Ancha Experimental Forest's Role in the Free-Air CO₂ Enrichment Large Wood Decomposition Experiment." Arizona-Nevada Academy of Science, 2012. http://hdl.handle.net/10150/301295.
Full text
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Marston, Bryce Kendrick. "Influence of the Mountain Pine Beetle disturbance on large wood dynamics and channel morphology in mountain streams." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35499.
Full textAbstract:
Doctor of PhilosophyDepartment of Geography
Charles W. Martin
Disturbance regimes are important determinants of both terrestrial and aquatic ecosystem structure and function. Disturbances may linger in the landscape and lag temporally, influencing stream ecosystem form and function for decades, if not centuries. The recent enhanced Mountain Pine Beetle (MPB) infestation in pine forests of the Rocky Mountain region has resulted in extensive tree mortality, producing the potential for significant increases in carbon supply to stream channels. To better understand MPB impacts on in-stream large wood (LW), a census was conducted in 30 headwater streams within the Medicine Bow National Forest in south-central Wyoming, across the temporal spectrum from early- to late-stage MPB-infestation. A subset of those streams exhibiting mean conditions at each level of infestation was surveyed to determine any significant differences in channel morphology or aquatic ecosystem function. Results indicate that wood loads related to the MPB-infestation significantly increase with time since initial infestation. However, even in late-stage infestation streams, many of the fallen MPB-killed trees are bridging across the channels and have yet to break and ramp down sufficiently enough to enter between the channel margins. Wood loads will continue to increase as more trees fall and bridging pieces decompose, break and then enter the channel. Measurable increases in the amount of LW with time since initial beetle infestation have both positive and negative effects on channel form and function. Although forest MPB-infestation has peaked in the study area, streams are still early on a curve of rapidly increasing wood loads that are beginning to affect streams and have the potential to dramatically increase the carbon base of regional stream ecosystems.
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Sampietro, Jean Alberto. "PROPRIEDADES MECÂNICAS E TRAFEGABILIDADE DE SOLOS EM PLANTIOS FLORESTAIS." Universidade Federal de Santa Maria, 2013. http://repositorio.ufsm.br/handle/1/3759.
Full textAbstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorMechanization significantly increased the productivity, quality and cost reduction for forests cultivation. However, it may be responsible for environmenral impacts, such as soil compaction, which is a result of traffic, mostly during wood harvesting operations. The objectives of this research were to evaluate the physical quality, trafficability and soil compaction due to traffic of wood harvesting machines of Eucalyptus sp. and developing functions to estimate physical and mechanical properties. The research was conducted in soils coming from implantation areas of Eucalyptus sp., and from an operational area of harvesting of Eucalyptus saligna Sm, belonging to CMPC Celulose Riograndense. To answer the hypotheses and meet the objectives, this work was divided into two studies. In Study I, five forest soils with different textural compositions were evaluated, determining physical quality indicators, trafficability indicators coming from the Proctor Normal test and uniaxial compression, and Atterberg consistency limits. The main results showed that both indicators of physical and trafficability were related to textural composition of soil, being estimated from these, as well as being influenced by different states of compaction. Furthermore, it was found that changing the bearing capacity has resulted in alteration of least limiting water range, which are related and, in this way, allowed to estimate the critical pressure for the plants growth. In Study II, we assessed the effect of different traffic intensities of a Harvester and a Forwarder on a Haplic Cambissol with sandy loam texture in Eucalyptus saligna Sm. stands, by determining the machines contact area and ground pressure exerted on soil, bulk density, pore size distribution, water retention curve, available water content, saturated hydraulic conductivity, air permeability, penetration resistance, compressibility, degree of compaction and shear strength. Were also evaluated the relationship of these properties and parameters. The main results indicated that few machines passes (one pass of Harvester and the four more of Forwarder) resulted in great part in soil deformation and changing in all evaluated properties and parameters. Mostly effects occurred until the depth of 20 cm. However, increasing the number of passes also caused changes in the deeper layers of soil. In general, the effects were higher in the area below within tracks, but, even so, effects occurred in areas between the wheels tracks and outside the areas of machines tracks. It was concluded that actions to minimize the compaction of forest soils should be associated with moisture conditions, traffic intensity and soil type.
A mecanização possibilitou aumento da produtividade, qualidade e redução de custos das atividades para o cultivo de florestas. Entretanto, tem sido responsável por impactos ambientais, destacando-se a compactação do solo, a qual é resultado do tráfego intenso de máquinas, principalmente nas operações de colheita. Os objetivos desta pesquisa foram avaliar a qualidade física, trafegabilidade e a compactação de solos, em função do tráfego de máquinas de colheita da madeira de Eucalyptus sp. e desenvolver funções para a estimativa de propriedades físicas e mecânicas. A pesquisa foi desenvolvida em solos advindos de áreas de implantação de povoamentos de Eucalyptus sp., e de uma área operacional de colheita de Eucalyptus saligna Sm., pertencentes à empresa CMPC Celulose Riograndense. Para responder as hipóteses e atender aos objetivos, o trabalho foi dividido em dois estudos. No Estudo I, foram avaliados cinco solos de uso florestal de diferentes composições texturais, determinando-se os indicadores de qualidade física, indicadores de trafegabilidade advindos do ensaio de Proctor Normal e compressão uniaxial, e limites de consistência. Os principais resultados mostraram que os indicadores de qualidade física e de trafegabilidade foram relacionados aos atributos texturais, podendo ser estimados a partir destes, além de serem influenciados por diferentes estados de compactação. Além disso, constatou-se que a alteração da capacidade de suporte resultou na alteração do intervalo hídrico ótimo, sendo estes relacionados, permitindo, assim, ser estimada a pressão crítica para o crescimento de plantas. No Estudo II, foi avaliado o efeito de diferentes intensidades de tráfego de um Harvester e um Forwarder sobre um Cambissolo Háplico de textura franco-arenosa em povoamentos de Eucalyptus saligna Smith, por meio da determinação da área de contato, pressão exercida pelas máquinas sobre o solo, densidade, distribuição de tamanho de poros, curva de retenção de água, conteúdo de água disponível, condutividade hidráulica do solo saturado, permeabilidade ao ar, resistência do solo à penetração, compressibilidade, grau de compactação e resistência ao cisalhamento. Foram avaliadas, também, as relações dessas propriedades e parâmetros. Os principais resultados indicaram que poucas passadas das máquinas (uma do Harvester e quatro do Forwarder) foram responsáveis em grande parte pela deformação e alteração de todas as propriedades e parâmetros. Os efeitos foram maiores até os 20 cm de profundidade. Entretanto, o aumento do número de passadas também causou alterações nas camadas mais profundas do solo. Em geral, os efeitos foram maiores na zona abaixo da trilha dos rodados, porém, ainda ocorreram efeitos nas zonas entre os rodados e fora da trilha dos rodados das máquinas. Conclui-se que as ações para minimização da compactação de solos florestais devem estar associadas às condições de umidade, intensidade de tráfego e tipo de solo.
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Gindaba, Jiregna. "Water and nutrient relations of selected tree species of Ethiopia." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16050.
Full textAbstract:
Dissertation (PhD (Bosb))--University of Stellenbosch, 2003.ENGLISH ABSTRACT: This study was conducted to evaluate and compare the water and nutrient relations of three indigenous deciduous tree species, viz., Cordia africana Lam., Croton macrostachyus Del., Millettia ferruginea (Hochst.) Baker and two widely planted eucalypts, viz., Eucalyptus camaldulensis Dehnh and Eucalyptus globulus Labill from Ethiopia. The study was organized as glasshouse and field observations in Ethiopia. Owing to the lack of baseline studies on the water and nutrient relations of the deciduous tree species, the glasshouse experiments involved a wide range of water and nutrient applications. Seedlings were grown with the supply of various levels of water and nutrients during which gas exchange, water potential, relative water content, tissue nutrient content and biomass production were measured. The field observations were limited to the study of surface root distribution and leaf nutrient composition of mature trees and their effects on soil nutrient pool. The observations were made on isolated trees and mixed or pure stands of trees in Badessa area, Eastern Ethiopia. The field site was selected because of the availability of the study species and suitability of the trees for the study. In the glasshouse, increased water deficit significantly reduced predawn leaf water potential, relative water content, stomatal conductance, photosynthetic rate, whole plant water use efficiency, plant height, diameter, leaf area and biomass production. Both of the eucalypts did not grow faster than the deciduous species under well-watered conditions unlike under water stress conditions. C. macrostachyus and C. africana had higher transpiration rates and tissue nutrient accumulations than the other species. They also demonstrated higher biomass allocation to roots than all the other species to support the intensive water and nutrient uptake rate. Due to the ability to re-orient its leaves to avoid direct solar irradiance, M. ferruginea maintained higher tissue water potential and relative water content than all the other species under water stress regimes. The impact of imposed drought was quick and more damaging to the eucalypts compared to the deciduous tree species indicating that the eucalypts may not survive extreme drought conditions unlike the deciduous species that drop their leaves and may remain dormant for weeks. The current study gave new experimental proof that E. globulus was more vulnerable to drought than E. camaldulensis. Soil N stress resulted in an overall reduction of tissue N concentration, N:P ratio, photosynthetic rate, stomatal conductance and photosynthetic water use efficiency in all the species studied. Pants with high foliar nitrogen concentration had higher photosynthetic capacities indicating that N plays a key role in photosynthesis and growth of all the studied species. The current study showed that for all the tree species, more attention has to be given to soil N than to P as soil P had minor effects on the photosynthetic activities of plants of all species compared to N.The investigation on tissue nutrient composition confirmed that N:P ratio could be used to detect Plimitation in plants. However, N:P ratio could not distinguish between N-limitation and combined limitations of N and P. The study of isolated C. africana and C. macrostachyus trees on soils in Badessa, Eastern Ethiopia indicated improved soil N, P and K under tree canopies whereas no effects were observed on the other soil nutrients studied. Similar to glasshouse conditions, C. macrostachyus and C. africana produced extensive surface roots, interfering with crops grown in association. Due to their high nutrient cycling potential the net effect on soil was positive. Comparison of E. camaldulensis woodlot and a mixed stand composed of deciduous species indicated that the fine root biomass in the surface soil under E. camaldulensis was about three times that under the mixed stand. The fine root biomass of E. camaldulensis inside the stand and 10 meters away from the stand were comparable in the surface soils showing the presence of root competition with adjacent crops. Therefore, planting of E. camaldulensis in association or adjacent to croplands should be avoided. Nutrient and carbon pool of soil inside the mixed stand was generally higher than that of E. camaldulensis indicating that trees of the mixed stand recycled more nutrients to the soil.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die verskille tussen water- en voedingstofverhoudings van drie inheemse blaarwisselemde boomsoorte te vergelyk, viz., Cordia africana Lam., Croton macrostachyus Del., Millettia ferruginea (Hochst.) Baker en twee bekende eucalyptus spesies, viz., Eucalyptus camaldulensis Dehnh en Eucalyptus globulus Labil van Etiopië. Die studie het bestaan uit kweekhuis- en veldobservasies in Etiopië. As gevolg van beperkte navorsing ten opsigte van water- en voedingstofverhoudings in bladwisselende boomsoorte, het die kweekhuis-eksperimente bestaan uit 'n wye verkeidenheid water- en voedingstoftoetse. Saailinge is gegroei deur verskillende vlakke van water- en voedingstowwe by te voeg. Gaswisseling, waterpotensiaal, relatiewe hoeveelheid water, hoeveelheid voedingstowwe en produksie van biomassa is gemeet. Die veldobservasies was beperk tot oppervlak-wortelverspreiding en blaarvoedingstof hoeveelhede van volwasse bome, sowel as die effek op grondvoedingstowwe. Observasies was beperk tot geïsoleerde, gemengde en een spesie opstande, in die Badessa area, Oos Etiopië. Die studiearea was gekies op grond van die voorkoms van die gekose boomsoorte, sowel as die toepaslikheid van die bome vir die studie. In die kweekhuis is gevind dat die verhoogte watertekort die pre-sonop blaarwaterpotensiaal, relatiewe hoeveelheid water, stomatiese geleiding, fotosintetiese tempo, heelplant water-gebruikseffektiwiteit, plant hoogte, diameter, blaararea en biomassa produksie beduidend verminder het. Nie een van die eucalyptus spesies het vinniger as die bladwisselende spesies onder voldoende hidrasie gegroei nie. Dit was egter nie die geval onder die waterbeperkte toestande nie. C. macrostachyus en C. africana het ‘n hoër transpirasie tempo sowel as weefselvoedingstof waardes gehad as die ander spesies. Hierdie boomsoorte se wortelbiomassa was ook meer as die ander spesies, om vir die tempo van water- en voedingstofopname te akkomodeer. As gevolg van die vermoë om blare te kan oriënteer om direkte sonlig te vookom, het M. ferruginea ‘n hoër water-weefselpotensiaal en relatiewe waterinname gehad in vergelyking met die ander boomsoorte in beperkte water toestande. Die impak van gëinisieerde droogte het vinnig voorgekom en het meer skade aan die eucalyptus aangerig in vergelyking met die bladwisselende boomsoorte. Dit dui aan dat die eucalyptus-spesie nie ekstreme droogte kan oorleef nie, waar bladwisselende spesies hul blare laat afval en vir weke aan een dormant kan bly. Hierdie studie gee eksperimentele bewyse dat E. globulus minder bestand is teen droogte as E. camaldulensis. Beperkte N in die grond het veroorsaak dat daar ‘n algemene vermindering van weefsel Nkonsentrasie, N:P ratio, fotosintetiese tempo, stomatiese geleiding en fotosintetiese watergebruiks effektiwiteit in al die bestudeerde spesies was. Plante wat oor hoër blaar-stikstofkonsentrasiesbeskik, het hoër fotosintetiese kapasiteite wat aandui dat N ‘n belangrike rol in fotosintese en die groei van al die bestudeerde spesies speel. Die oorhoofse bevindings van die studie was, dat daar meer aandag gegee moet word aan grond-N as P omdat grond-P net ‘n kleiner rol speel in die fotosintetiese aktiwiteite van plante van al die spesies in vergelyking met N. Die ondersoek na weefselvoedingstof hoeveelhede het bewys dat die N:P ratio gebruik kan word om P-tekorte in plante aan te dui. Die N:P ratio kan egter nie die verskil in N-tekorte en gekombineerde tekorte van N en P aandui nie. Die studie van die geïsoleerde C. africana en C. macrostachyus bome op grondtipes in Badessa, Oos Etiopië het verbeterde grond-N, P en K onder kroondak gebiede getoon, daar was egter geen verskille in die ander grondvoedingstowwe wat bestudeer is nie. In toestande gelykstaande aan die van die kweekhuis, het C. macrostachyus en C. africana meer oppervlaksswortels ontwikkel. Die toename aan oppervlakswortels het ingedring op gewasse wat in assosiasie gegroei is, dit het egter ‘n positiewe effek op die grond gehad as gevolg van die hoë voedingstof-siklus-potensiaal. Die E. camaldulensis opstand is gevergelyk met ‘n gemengde opstand van bladwisselende spesies waar daar gevind is dat die fynwortel biomassa in die oppervlak grond onder die E. camaldulensis ongeveer drie keer soveel was as die van onder die gemengde opstand. Kompetisie met aangrensende gewasse is aangeui deurdat die fynwortel biomassa van E. camaldulensis binne die opstand en 10 meter weg van die opstand vergelykbaar was in die oppervlakgronde. Dit dui dus aan dat die plant van E. camaldulensis in assosiasie of aangrensend aan gewasse vermy moet word. Die teenwoordigheid van voedingstowwe en koolstof in die grond van die gemengde opstand was oor die algemeen hoër as die van die E. camaldulensis. Dit is ‘n aanduiding dat die bome van die gemengde opstand meer voedingstowwe aan die grond verskaf.
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Ismailov, Taner. "Quantification of resin acids, fatty acids and sterols in process and waste water from forest industry." Thesis, Karlstads universitet, Avdelningen för kemi och biomedicinsk vetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-28179.
Full textAbstract:
This work focuses on wood extractives in effluents from the CTMP plant at Skoghall Mill. Pulp and paper industry effluents contain mostly natural compounds which are part of the trees. They are toxic to aquatic life but harmless in nature, as they are present in low concentrations. Processing tons of wood, such as in a pulp mill, strongly increases the concentrations of the toxic compounds (Ali, M. and Sreekrishnan, T., 2001) which have to be treated before transferring to the aquatic environment.Extractives can be found in different forms, as micelles soluble in water, unprocessed in fibers or absorbed on the surface of fibers. It is important to know in which forms extractives are mostly present in the effluent, so that they can be treated more efficiently. It is desired to have extractives absorbed on the fibers and fibrils present in the waste water, so they can be separated from the water and treated separately, e.g. burned for energy recovery. Dissolved extractives complicate the oxygen transfer in an aerated biological treatment step with their surface active properties (Sandberg, 2012).The aim of this study is quantification of extractives on the fibers suspended in the waste water and extractives dissolved in the water. The distribution between the two forms is an important input when designing future effluent treatment. Wood extractives itself are a wide group with different compounds. This work focuses on the main groups present in waste water: resin acids, free and esterified fatty acids and, free and esterified sterols. These groups are analyzed in different process waters and waste water before the waste water treatment plant. The measured concentrations of extractives were as expected, higher in process and effluent waters, lower in white water. Most of the extract was dissolved in the water and unfortunately fiber samples contained very low concentration from the total extract in the samples.
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Buchelt, Beate, Tobias Dietrich, and André Wagenführ. "Testing of set recovery of unmodified and furfurylated densified wood by means of water storage and alternating climate tests." De Gruyter, 2014. https://tud.qucosa.de/id/qucosa%3A38557.
Full textAbstract:
Densification is a well-known method for improving the mechanical properties of wood. In the present study, unmodified and furfurylated wood samples were densified and submitted to cyclic water storage tests and cyclic alternating climate tests. Swelling coefficients and spring-back data were determined for the evaluation of the quality of densification. The study shows that results depend on the test method applied. Simple water storage tests do not reflect the behavior of densified wood in the high humidity range. The spring-back data of unmodified samples are more influenced by the testing method than those of the furfurylated ones.
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Moreno, Chan Julian. "Moisture content in radiata pine wood : implications for wood quality and water-stress response : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Forestry, School of Forestry, College of Engineering, University of Canterbury /." Thesis, University of Canterbury. School of Forestry, 2007. http://hdl.handle.net/10092/1217.
Full textAbstract:
This thesis studied the influence of moisture content on the dynamic estimation of stiffness in wood of Pinus radiata D. Don. This is an important non-destructive measure for estimation of stiffness in standing trees, logs and lumber. Moisture content affects both acoustic velocity and density in the fundamental equation of dynamic MOE (DMOE = V²ρ, where V = acoustic velocity and ρ = density). Investigation included measurements with boards in the laboratory considering moisture contents below and above FSP as well as temperatures below and above 0°C. This also included field measurements of trees in contrasting climate sites and over different seasons including a long drought. Methods for measuring green density and moisture content and the patterns of variation of these parameters were also investigated. A secondary component of this thesis explored the wood quality and some mechanisms of tree response to water stress in two contrasting sites in terms or rainfall and water deficits in a region of Australia. The large increases in DMOE for frozen wood above the FSP (4.5 to 6 GPa) will limit the use of DMOE for grading logs in regions with freezing winters. Results from the experiment remeasuring young trees and the upper range of moisture content and temperatures above 0°C from the experiment with boards showed small to moderate variation in DMOE (0.1 to 1 GPa) which calls for further investigation on analytical procedures for adjustment of DMOE. Such procedures should consider that variations in acoustic velocity and density with changes in moisture content are not proportional and that there are counteracting effects between the two parameters. It remains to be investigated whether the typical variation (under normal climate conditions) in sapwood green density observed in our experiments has some implications for the use of DMOE. On the other hand, it is anticipated that the large differences along the stem and among stands in whole-section green density may bias DMOE measurements in logs for resource assessment. This also needs to be investigated. A comparison between acoustic velocity alone and DMOE for resource assessment under different scenarios is recommended. The study in two contrasting climate sites (high-altitude vs. warm-dry) in the Hume region of Forests NSW, Australia, including young (10-11 years) and mature trees (34 36 years) of radiata pine showed distinctive short and long-term responses of trees to cope with the water-limiting environment. In response to long-term water deficits the warm-dry site developed heartwood and thus reduced sapwood earlier and at faster rates than the high-altitude site. The onset of heartwood formation seemed to be triggered by some site threshold for water use as broadly indicated by the sapwood area/ha. The latter was consistently lower for the warm-dry site across the different stands. The warm-dry site also showed increased short-term responses to water stress and these were interpreted as seasonal mechanisms of the trees to cope with the limiting environment. The trees compensated for the lower available moisture and higher transpiration rates by lowering their saturation and disrupting water conduction at some points (cavitation). The inverse trends of cavitation spots and cavitation bands with height in the stem suggested the trees have different strategies to sacrifice conducting xylem depending on the position on the stem. Finally, it is suggested that saturation tended to fall to critical 'safe' levels as a result of water stress and this varied depending on age, site, and position in the stem. Significant decreases in DMOE and basic density were observed for the warm-dry site and were attributed to lower proportions of latewood due to lower rainfall for that site during the period of latewood formation. These showed no obvious association with any of the long-term water-stress traits (sapwood percentage and number of heartwood rings).
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Harper, Elizabeth B. "The role of terrrestrial habitat in the population dynamics and conservation of pond-breeding amphibians." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4693.
Full textAbstract:
Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 25, 2007) Vita. Includes bibliographical references.