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Mechanical analysis of scarf joint fastened using cylindrical wooden dowel
Tippner, J. ; Milch, J. ; Kunecký, Jiří ; Kloiber, Michal ; Brabec, M. ; Sebera, V.
Traditional all-wooden woodworking joints play an important role in the behaviour of timber structures. These joints are also widely used when historically valuable constructions are being reconstructed and the connections are usually the masterpieces that testify to the high carpentry skills and knowledges of the overall mechanical behaviour. Within historical timber structures traditional carpentry joints were used while wooden dowel fixed mutual position of elements. Main aim of this study was to contribute to knowledge base about prediction and analysis of the mechanical performance of frequently used scarf joints made from spruce wood fastened using oak dowels. The objectives were to determine the joints' slip moduli and load-carrying capacity by means of theoretical and experimental approaches, in next to assess the mechanical behaviour of dowels through experimental investigation, and finally to perform a strain analysis of dowels. For these purposes, the optical technique employing three-dimensional full-field digital image correlation was used. The experiments were done on the full-scale specimens meeting the requirements of European standards (EN 383 and EN 26891), which were made from Norway spruce (Picea abies L. Karst.) and English oak (Quercus robur L.). The mechanical load consisted in tensile parallel and perpendicular to grain direction within the main components. The results of this study showed good correlation between theoretical approach based on based on Beam on Elastic Foundation theory and European yield model theory and experimental observations.
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Determination of soluble phenolics in common spruce stands using hyperspectral data
Buřičová, Michaela ; Kupková, Lucie (advisor) ; Petruchová, Jana (referee)
The thesis deals with lignin and soluble phenolic determination in Norway spruce foliace using hyperspectral data. A literature overview is focused on the analysis of lignin and soluble phenolics. The practical part focuses on the determination of wavelenghts intervals which are suitable for the detection of lignin and soluble phenolics. There is applied regression analysis for the determination of relationship between the foliage spectra and the content of biochemical substances for the chosen spektrum intervals. Indexes NDLI, mNDLI and RLI were than calculated. HyMap hyperspectral airborne images from 2009 and 2010 for the area of Sokolov, spectral curves of dry matter and fresh branches of Norway spruce and laboratory determination of lignin and soluble phenolics content were the inputs for the analyses. Maps of lignin content in Norway spruce are the final output of the work. Keywords: Norway spruce (Picea Abies), lignin, soluble phenolics, PLS (partial least square) method, multiple Stepwise regression, NDLI
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Effects of management and natural disturbance on oribatid mites in montane forest
FARSKÁ, Jitka
The thesis studied effects of forest management and natural disturbance on oribatid mites in montane forests in South Bohemia (Czech Republic). We focused on the influence of (1) spruce monoculture establishment on the former beech forest, (2) management intensification in spruce forest and (3) forest dieback after bark-beetle outbreak. The impacts were pronounced especially like changes in species composition and distribution of functional traits.
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Growing of over - growth tree species
KOSTOHRYZOVÁ, Lenka
The comparison of agronomical practices and land capability of selected deciduous with coniferous wood species, especially fast growing tree species on agricultural land, is the theme of this bachelor work. This work deals with the cultivation of fast growing tree species, the comparison of their growth figures and agricultural techniques. Fast growing tree species were cultivated in these localities: Svatý Jan nad Malší (Chlum nad Malší), Všemyslice- Neznašov and Lesy města Český Krumlov s.r.o. The research was focused on the comparison of yields of deciduous (poplar) with coniferous trees (spruce, larch), agricultural techniques. There is the comparison of yields with yields from the available literature, in conclusion.
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