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Analysis of methods for determining wood moisture by non-destructive methods
Změlík, Jiří ; Zach, Jiří (referee) ; Vaněrek, Jan (advisor)
Subject of this bachelor thesis is the analysis and comparison of hygrometers considering their price, availability and applicability. Theoretical part compared available types of hygrometers based on their operating principle. Subsequently, resistance, capacitive and microwave portable hygrometers were compared in more detail. There were five reviewed hygrometers in total, with three of them capacitive and one of each resistance and microwave. The measurement was performed on beech and spruce trees at gravimetrically known humidity, ranging from extremely low to extremely high values (even out of bounds recommended by the manufacturer). The evaluation of the methods was performed according to the Saaty´s AHP method. Hygrometers were then selected by their optimization. After the experimental part, the suitability of individual methods was determined. The best method was capacitive, followed by resistance and the worst microwave method.
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Vplyv extrémneho umyvacieho procesu na pevnosť v ohybe lepeného spoja v listnatom dreve
Tuhý, Dušan
The diploma thesis is focused on the issue of the effect of the washing process on the bending strength of the glued joint in a special solid wood panel made of hardwood. The goal was to analyze currently available adhesives and types of joints in solid wood panels and to deal with the issue of the washing process and its influence. The selected glue was PVAc glue Rakoll ® GXL 4 and a butt joint, and then the changes in bending strength were compared on wood samples from beech, oak, ash and maple after thirty cycles of an intensive washing process using cleaning tablets and subsequent acclimatization of the samples. These were compared with samples that did not undergo the cleaning process.
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Ztráta účinku výchovných zásahů ve smíšeném dubo-bukovém porostu (36A8) na ŠLP Křtiny
Černíková, Karla
The aim of the work was to evaluate the loss of the effect of individual thinnings in the oak-beech forest in Training Forest Enterprise. A research area of 0.84 ha was established in 1989 in a stand that was 49 years old. Thinnings were carried out on this research area (crown, low and Voropanov-Borgrewe thinning). Part of the area was left to natural development (reference area), which took as a comparison. The height, height of the base of the crowns, thickness was measured and the form of the trunk and crown according to Polansky's classification were estimated on individual tree. Measurements were carried out in 1989, 1999, 2005, 2010, 2015 and 2020. There was no response for the thickness when the variants of the thinning method were compared with the reference plots. In the first 10 years, the height increase was recorded in the case of Voropanov-Borgrewe thinning for the oak, and also, in the reference area, where the weakest and lowest oaks died. After 15 years, the height curves of Voropanov-Borgrewe thinning and reference plots were similar as the other methods, and the thinning effect was lost. In the beech, there was no effect of the thinning methods on the height. The effect of self-thinning was very successfully in beech, which is most noticeable in recent years. In the oak, there was no effect of the thinning methods for the parameter the height of the base of the crown compared to natural development. In the beech, there was the effective thinning method in the case of Voropanov-Borgrewe thinning. The factors that were evaluated based on the Polansky classification (the form of the trunk and crown) did not show improvement in oak and beech in any case of thinning methods. In conclusion, we can say that the final evaluation of the effectiveness of thinning methods, which were carried out only once, is not considered significant compared to the natural development of the stand.
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Zhodnocení škod mrazem na zakládaných lesních kulturách v podmínkách ŠLP ML Křtiny
Patáková, Aneta
On the forest property managed by ŠLP ML Křtiny, an assessment of the damage caused by late frosts on the plantations of forest trees was carried out. Data collection took place at the beginning of the growing season (from May to June), when woody plants begin to sprout and are exposed to the greatest risk of damage from late frosts. Frost events were measured using TMS data loggers, which record the ground air temperature using temperature sensors. The assessment was carried out on young cultures of beech, oak, spruce and fir with a maximum age of 3 years. A total of 28 leguminous areas of different sizes (categories up to 0.1; 0.11 – 0.5 and over 0.51 ha) were evaluated, on which the average damage of the assimilation apparatus was determined on a representative sample of 100 seedlings. The results showed that the most sensitive tree species to late frosts are beech (damaged 56.9 ±30.7% of seedlings) and fir (52.4 ±46.6%).
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Vliv modifikace bukového dřeva na parametry obrábění
Vencl, Jakub
The Bachelor´s thesis is focused on the observation of effect of beech wood modification on the energy parameters of chip machining. It is about a comparison of modifications of beech, i.e. Lignamon and Bendywood which will be compared to native beech. In the case of native wood, the results of experimental measurements were also compared to results calculated with conventional methods. The methods which were used were: Technological-statistical and Analytical method. The primary investigation was cutting force. It was found that modification of beech wood does not have a statistically significant effect on machining parameters. In a comparison of two theoretical methods in the case of native wood was found that the Technological-statistical method had better sameness with experiment. The disadvantege of those methods is that they cannot be used for modified wood.
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Analysis of methods for determining wood moisture by non-destructive methods
Změlík, Jiří ; Zach, Jiří (referee) ; Vaněrek, Jan (advisor)
Subject of this bachelor thesis is the analysis and comparison of hygrometers considering their price, availability and applicability. Theoretical part compared available types of hygrometers based on their operating principle. Subsequently, resistance, capacitive and microwave portable hygrometers were compared in more detail. There were five reviewed hygrometers in total, with three of them capacitive and one of each resistance and microwave. The measurement was performed on beech and spruce trees at gravimetrically known humidity, ranging from extremely low to extremely high values (even out of bounds recommended by the manufacturer). The evaluation of the methods was performed according to the Saaty´s AHP method. Hygrometers were then selected by their optimization. After the experimental part, the suitability of individual methods was determined. The best method was capacitive, followed by resistance and the worst microwave method.
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Emise prašnosti při broušení tepelně modifikovaného buku
Železný, Antonín
The thesis is focused on wood dust generated during sanding modified beech. The analysis concerns the characteristics and composition of this dust. The thesis addresses also the danger for human health exposed to the wood dust and its impact on the work environment. The theoretical part is focused on properties and biological effects of airborne dust on the human body as well as the thermal modification of wood. The experimental part was carried out on a test stand to simulate standard sanding. For our experiment three samples were selected, namely a modified beech at 180 °C, 200 °C and a native beech. In order to evaluate the incidence of wood dust, a methodology was designed to determine the representation of individual fractions of wood particles. Very fine particles (particles smaller than 100 micrometres) were subjected to microscopic and probabilistic analysis.
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Vliv impregnace přírodní a syntetické pryskyřice na vybrané mechanické a fyzikální vlastnosti bukového dřeva
Syrovátko, Jakub
The aim of this thesis was to analyze the influence of natural synthetic resins impregnation on selected material properties of wood. Beech (Fagus sylvatica L.) wood used in present study, as a wood species considered as easy to be impregnated. Specimens with dimensions of 20 × 20× 30mm were vacuum impregnated by natural and synthetic resins at 20 kPa for 1.5 hours. Afterwards, the weight percentage gain (WPG) was evaluated and modulus of rupture (MOR) and modulus of elasticity (MOE) in compression parallel to the grain were experimentally determined. Obtained data sets were statistically analyzed and results were discussed and compared to relevant literature.
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Rekonstrukce přípravných porostů břízy bělokoré podsadbami
Souchová, Jana
The aim of the Dissertation Thesis was to assess the oak and fir tree seedling growth rate in the Deštná-Horákova Lhota, Bystřice nad Pernštejnem and Opatovec - Kukle areas. Measurements took place on 22 areas with various intensity release preliminary growth. The following parameters were measured: current height of the above-ground tree plant parts and its height in previous year, yearly growth rate, length of sideways growing tree parts, width of tree crown, height of dual and triple tree trunk parts, deflection of trunk from its vertical axis, width and length of leaf or needle, root neck diameter, multiple tree trunk, straightness of the trunk, multiple tree top, vitality of the plant, damages through animal bites or horn scrapings. It can be concluded that each variation results in different growth rate of the undergrowth. It has been found that the best growth rate under birch tree plants was achieved in a narrow strip of bare of the tree plant beds. The worst growth rate, on the other hand, was observed in the 0.5 tree trunk variation.
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