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Using homogenization and nanoindentation for microfibril angle determination of spruce
Kucíková, L. ; Hrbek, Vladimír ; Vorel, J. ; Šejnoha, M.
This paper is concerned with the evaluation of microfibril angle of spruce. The microfibril angle is defined as an inclination of microfibrils from the longitudinal axis, the direction of lumens. It is well known and further supported by the present study that the microfibril angle has a great influence on the final mechanical properties of wood. This angle could be measured either directly using, e.g. polarisation microscopy, X-ray diffraction, infrared spectroscopy, or indirectly, as used in this study, by employing the nanoindentation measurements. Therein, the measured indentation modulus is compared with that obtained numerically using the anisotropic theory of indentation. The latter one depends on the entire stiffness matrix derived through homogenization and the searched microfibril angle. In view of the cell wall microstructure, the effective cell properties were found using the two-step micromechanical homogenization adopting both the Self-consistent and Mori-Tanaka methods.
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Forest management of the Dominican order in the Mimoň region
Nejedlý, Ondřej ; Foltýn, Dušan (advisor) ; Hnilica, Jiří (referee)
This thesis deals with the forest management of the Dominican Order in Mimoň area. Specifically, it focuses mainly on the area of Hamr nad Jezerem, in the years 1931-1938 and the last years of the active duty of the Directorate of the Dominican forest management in 1945-1950. The emphasis of the thesis is based on the description of the previously uncharted historical chapter of the Dominican order in this area, especially with regard to the economic activity of the forest administration in this given period and legal aspects of the whole issue with the acquisition, loss and subsequent efforts to return these properties. The Fund no. 37 in the Archive of the Dominican order, deposited in the 1st Department of the National archive in Prague, was used as the main source, subsequently supplemented by specialized and professional literature, an interview with the legal representative of the Dominican order in Prague in the case of restitution and also by few internet resources. KEYWORDS Dominicans, forestry, Hamr, Restitution, Hospitaller Order of Saint John, count Hartig, hunting, hunting area, logging, the first Czechoslovak Republic. Karl Waldstein, pine, spruce, lumbermill, Ministry of Agriculture, Military training area Ralsko, land reform, land reform review..
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Fine particles emitted from laboratory combustion tests
Hájek, Ondřej ; Šnajdárek, Ladislav (referee) ; Pospíšil, Jiří (advisor)
This bachelor thesis is aimed at fine particles emitted from laboratory combustion tests of biomass. The theoretical part of this thesis is about common features and usual ways of using biomass. After this broad chapter there is specifically described combustion and all its products including emission of gasses and fine particles. The main task of this thesis is about an experiment combining two analyses. First is the thermogravimetric analysis and the second is measuring size and number of fine particles in the range of 18 to 550 nanometers. The final chapter is about evaluation of measured results from 4 different spruce samples.
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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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Sledování dynamiky obnovy lesa v oblasti postižené kůrovcem v NP Šumava
Česká zemědělská univerzita v Praze, Fakulta lesnická a environmentální, Katedra pěstování lesů, Praha ; Podrázský, Vilém
Cílem projektu je zhodnocení spontánních procesů v oblasti lesa postiženého kůrovcem na území NP Šumava. V souboru trvalých výzkumných ploch je hodnocen vývoj půd, fytocenóz a lesních porostů na lokalitách s různou spontánní dynamikou a s různým managementem. V roce 2004 bylo provedeno průběžné hodnocení dynamiky přirozeného zmlazení na výzkumných plochách (VP), fytocenologické periodické snímkování na VP na LS Modrava a Plechý, průběžné vyhodnocení hydrické funkce lesa na třech sledovaných povodích. Zpráva popisuje množství a strukturu mrtvého dřeva a jeho význam pro obnovu lesa ve smrkovém horském lese v oblasti rezervace Trojmezní, strukturu a dynamiku horského smrkového lesa ve výškovém transektu na lokalitě Plechý, dynamiku rozpadu horského smrkového lesa ve výškovém transektu na lokalitě Velká Mokrůvka v bezzásahovém pásmu NP Šumava, zdravotní stav porostů, vyhodnocení spontánní obnovy porostů v letech 1998-2004, hydrickou funkci lesa, mykologický průzkum, stav lesních fytocenóz, stav lesních půd. Zpráva je doplněna přehledem publikací vzniklých v rámci řešení projektu, finančním vyúčtováním a tabulkovými výsledky fytocenologického výzkumu.
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