National Repository of Grey Literature 57 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Hodnocení přesnosti měření vlhkosti dřeva smrku při použití elektrického odporového vlhkoměru
Ondráček, Michal
This bachelor thesis focuses on the evaluation of the accuracy of spruce wood moisture measurement using an electrical resistance hygrometer. In the theoretical part, the basic properties of wood and its influence on moisture measurement are described. Furthermore, the different methods of measuring wood moisture are described and, above all, the principle of measurement using an electrical resistance hygrometer is discussed in detail. In the practical part, the moisture content of spruce wood was measured with three electric resistance moisture meters and the results were then compared with a reference gravimetric measurement method. Moisture meter No. 1 showed the most accurate results in determining the moisture content, but even it did not come close to the actual moisture content determined by gravimetry. Moisture meters 2 and 3 obtained identical measurements, but the measured moisture content differed significantly from the actual moisture content of the wood determined gravimetrically. These two hygrometers showed worse results than hygrometer No 1.
Vliv teploty lepidla a povrchu adherendu na hloubku penetrace lepidla do masivního dřeva
Voldřichová, Anna
The final thesis deals with the influence of different gluing conditions on the depth of penetration of the adhesive into the surface of solid wood, specifically of the influence of increased pressure during pressing. Furthermore, the thesis investigates the effect of penetration on the strength of the glued joint under tensile loading. Specimens of spruce and oak wood were glued with UF glue and PVAC glue, pressed under different compression pressures and then subjected to tensile test. SEM analysis on an electron microscope was used to evaluate the depth of penetration. The results of the investigation of the effect of ink on the strength of the bonded joint and the penetration depth of the adhesive into the material are also included. The ink was used in the adhesive mixtures for the purpose of colouring the bonded joint.
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%).
Sequestration of soil organic matter in broadleaf and coniferous forests in soil at various stages of pedogenesis
Hüblová, Lucie ; Frouz, Jan (advisor) ; Vindušková, Olga (referee)
Soil organic matter (SOM) is an important component of the soil. SOM is responsible for availability of nutrients for plants and soil organisms, formation of soil structure and soils water-holding capacity. SOM is made up of organic matter (OM) of plant and animal origin at various stages of decomposition. SOM can be divided into several components called fractions. Fractions differ between each other in their resistance against decomposition. Main SOM fractions are: (1) free floating particulate organic matter (FPOM) and (2) OM bound to soil mineral surfaces in various ways (MAOM) - OH inside macro- and microaggregates and OM bound to silt and clay surfaces (S+C). It is assumed that MAOM fraction becomes C saturated during soil development and no more C can be sequestered in it. Other fractions, particularly FPOM, that are not dominant C storage in the initial stages of soil development become more important in the later stages and amount of C stored in them increases. However, there is scarcity of studies that examine this assumption. In this work I studied the hypothesis that soils in different stage of development will differ in the amount of C stored in different fractions. On top of that, this difference will be affected by the dominant tree species growing on the soil and the effect of tree...
Způsoby likvidace Lýkožrouta smrkového
ŘÍHA, Jan
The bachelor thesis deals with the morphology and life cycle of the spruce lichen-eater. The main focus is on measures to combat the spruce lichen-eater and an overview of such techniques and technologies designed for that. Here I describe the issue of swarming, wintering and what bark beetles have natural enemies. The bachelor's thesis describes how to treat the lichen-eater, how to prevent it, and mainly there are instructions on how to use individual technologies for its disposal. It is a mechanical technology of liquidation or even chemical liquidation. There is also a research overview of articles from international databases and extracts from them in my words. The aim of this work is to create a research overview of the biology and methods of disposal of the spruce lichen-eater.
Methodology of treatment of infested wood by spruce bark beetle (Ips typographus) using EDN(R) fumigation preparation
Stejskal, Václav ; Hnátek, Jonáš ; Kadlec, Jakub ; Aulický, Radek
The methodology describes the effective application of EDN(R) in the treatment of unprocessed wooden logs on heaps in forest. This methodology provides the technical and biological information regarding effective application of EDN(R) with the active substance ethanedinitrile in the treatment of harvested spruce logs in order to reduce the risk of spreading European spruce bark beetle (Ips typographus). The methodology describes technical specifications and the use of special application equipment for the application of the liquefied EDN from cylinders using nitrogen as an inert drive to treat harvested coniferous wood. The methodology is based on original experimental data. The general goal of the methodology was to help mitigate the current bark beetle calamity in the Czech Republic. The specific objectives of the methodology were to provide (i) objective and original information for the purposes of professional pest control staff and supervisory authorities (especially CISTA) on the method and procedure for treating wood using the EDN(R) product; ii) methodological documents necessary for repeated rapid preparation of the CISTA regulation for the use of EDN for the treatment of landfills under tarpaulin; and (iii) to provide a brief overview of published scientific information and an evaluation of the methods and preparations used for phyto-quarantine treatment of wood against European spruce bark beetle (Ips typographus) in comparison with the new procedure described in this methodology (i.e. EDN-fumigation of piles of spruce-logs under a plastic sheet).
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Study of quantitative parameters of Norway spruce needle structure under the effect of elevated CO₂ concentration and different irradiance
Kubínová, Zuzana ; Lhotáková, Zuzana (advisor) ; Urban, Otmar (referee) ; Gebauer, Roman (referee)
Zuzana Kubínová: Study of Quantitative Parameters of Norway Spruce Needle Structure under the Effect of Elevated CO2 Concentration and Different Irradiance, Doctoral Thesis, Prague 2019 Abstract Atmospheric concentration of CO2 is increasing, while its influence on plants is still not fully elucidated. Norway spruce (Picea abies L. Karst.) is an abundant conifer tree in European temperate and boreal forests, which behave as carbon sink in the global carbon cycle. The physiological response to elevated CO2 concentration may be interconnected with changes in leaf anatomy and morphology. Needle structure is also determined by other factors in addition to CO2 concentration, irradiance being the most important one. Thus, effect of irradiance was also included in our studies. The effects of elevated CO2 concentration and irradiance on Norway spruce needle structure were studied using new applications of well-established quantitative methods and novel methods enabling effective and unbiased analysis of needle structural traits. The General Procrustes analysis showed to be effective for needle shape on cross section comparison and the disector method proved to be suitable for chloroplast number estimates. The influence of elevated CO2 concentration and different irradiance on needle structure was studied at two...
Establishment and growth of spruces in reclaimed and unreclaimed plots on heaps after coal mining
Spurná, Veronika ; Frouz, Jan (advisor) ; Reif, Jiří (referee)
Coal is the most important raw material mined in our country. The mining acitivity creates huge impact on the landscape. The aim of the thesis is to compare the attachment of spruces on spoil tips created by coal mining and their growth during spontaneous succession and reclamation. The studied non-recultivated areas are overgrown with spontaneous vegetation consisting mainly of willow (Salix caprea), white birch (Betula pendula) and aspen poplar (Populus tremula L.). The reclaimed area only consists of planted Norway spruce (Picea abies). The density of localities, age and height structure, layout on terrain waves and distance from the edge of the dump were studied. Spruces were also mapped using GPS. The density of spruce vegetation on reclaimed areas is significantly higher than on succession, however, their growth is slower. On non-reclaimed areas, the growth of already attached spruces is significantly faster than on reclaimed areas. The results show a higher attachment of spruces on the slopes of the waves, especially on the northern leeward side, rather than in the troughs or on the peaks. The results show the possibility of undercutting succession areas with climax trees as a promising method of reclamation. Keywords: spruce, succession, reclamation, establishment of trees, density of trees
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.
The analysis of acoustic properties of innovative wood-based materials
Svojanovský, Jan ; Nop, Patrik (referee) ; Jirásek, Ondřej (advisor)
The content of this work is research of innovative wood-based materials in the acous-tic perspective. Basically, the goal is to determine the influence of the internal structure of the wood-based material on variables, which are sound speed, acoustic resistance, or acous-tic constant. In total were measured 15 samples, each one was made in a different way. Each sam-ple was weighted, and the length of its sides was measured. By using the ultra sonic timer, it was measured the time of the sound impulses, which go through the samples in all of their axes for the purpose of observation the influence the fibers on speed of sound in the materi-al. The next thing to do was to determine another magnitude, which describe acoustic of the material. All measurements were taken in room conditions (room humidity). Six of the sam-ples, which were randomly selected from those 15 samples, were measured once again after two weeks. In those two weeks were all the samples saved in air-conditioned place in which was the room humidity distinct lower. In the end all the samples were compared with each other and they were also com-pared with materials which are commonly used in production of musical instruments or acoustic components. Possible use in the music industry was assigned to each sample.

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