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Experiment CAPEX-U: Současnost a Budoucnost
Frolov, Oleksandr ; Koláček, Karel ; Štraus, Jaroslav ; Schmidt, Jiří ; Boháček, Vladislav ; Prukner, Václav
A new pulse capillary discharge driver with a laser-triggered main spark gap has been developed. The assembled CAPEX-U device consists of a Marx generator, of a pulse forming line, a gas-filled laser-triggered spark gap and a ceramic capillary. Its design was supported by mapping of electrostatic fields in the most exposed regions and by analysis of an equivalent circuit. Operation of the laser-triggered spark gap was tested on a single-channel model. In the paper, the results of the modelling and of the first electrical tests of the whole device (capillary current and voltage at the end of pulse forming line) are presented.
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Physical Load Analysis In Woman's Beach Volleyball
Maciolková, Hana ; Vorálek, Rostislav (advisor) ; Buchtel, Jaroslav (referee)
Title: Physical Load Analysis In Woman's Beach Volleyball Objectives: The objective is to examine time characteristics, cardiac strain, movement pattern and the individua! volleyball skills in woman playing beach volleyball. The results will help aid athletes and coaches to improve individua} and team performance in the sport. Methods: Analyses of the thirteen game records were used to compile data for statistical time measurements, movement pattems and individua! volleyball skill. Through the use of sport testers, four individua} athletes in four separate toumaments had their heart rates recorded. These heart rates were further analyzed to collect the appropriate data for cardiac strain characteristics. Results: The average game time was 37 minutes with 5 - 9 seconds exercise loads and 15 seconds recovery time. Beach volleyball is high to middle level intensity game with mixed aerobic- anaerobic energy supply system in use. The average heart rate falls in the interval of 150 and 180. The jumping load is about 41 and more jumps counting serve jump, block and spike. The prevalent movement distance is within 4 meter range. The results also shows that the blocking player is under large physical stress while changing repeteadly position between defence on the net and in the field. Keywords: Beach...
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The structural and the fundamental mechanical properties of intermatallics on the base of TiAl
Krahula, Karel ; Dlouhý, Ivo
Gamma TiAl alloys are emerging as a pervasive structural material. Remarkable progresses have been made through refining lamellar microstructure and grains, microalloying, chemistry modification, process development and/or their combination. The main thrust was to enhance resistance to creep deformation, oxidation and high cycle fatigue deformation/failure. Less or even no knowledge have been obtained in the field of the intermetalics fracture at uniaxial or bending loading, there are missing data about their behaviour at the presence of cracks and other defects. The reason is simply in the other properties that are key from application point of view. Due to their brittleness at temperature close to room temperature the investigation of the intermetalics fracture is complicated but promissible provided it bring ideas for the further development of the alloying and microstructure. The paper is focused on the first steps in this field.
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Plasmodiophora brassicae on winter rape
Řičařová, Veronika ; Ryšánek, Pavel (advisor) ; Jaroslav, Jaroslav (referee)
Winter oilseed rape (Brassica napus) is an important crop in the Czech Republic. Clubroot disease caused by the pathogen Plasmodiophora brassicae Wor. is a serious and still-growing problem for oilseed rape growers. Research on P. brassicae in the Czech Republic is therefore important for the development of effective strategies to manage clubroot under Czech environmental conditions.
One of the aims of this study was monitoring of this pathogen. The disease was previously widespread in commercial vegetable production and in hobby gardens. Since 2010, oilseed rape clubroot started to spread across the whole country, whereas it had previously only been observed in the northeast. Clubroot occurrence was monitored for five years by the Union of Oilseed Growers and Processors on the basis of disease symptoms present on oilseed rape fields. The presence of P. brassicae and clubroot symptoms were reported in all regions of the Czech Republic, except the Ústecký Region, and in 31 out of 76 districts. At present, at least 130 fields are known to be infested by the pathogen, but this number is very likely underestimated. Some soil samples were also tested by conventional PCR (polymerase chain reaction) to evaluate the possibility of their usage. All 14 suspected samples tested positive by PCR.
The next aim was to evaluate the pathotype composition of P. brassicae populations from the Czech Republic, according to the three evaluation systems, and to determine soil inoculum loads for representative fields via traditional end-point PCR as well as quantitative PCR analysis. There were considerable differences between the populations of P. brassicae, and the number of pathotypes varied depending on the evaluation system and the threshold used to distinguish susceptible vs. resistant plant reactions. This is the first study comparing the effect of different thresholds. Using an index of disease (ID) of 25 % to distinguish susceptible vs. resistants reactions, there was a total of five pathotypes identified based on the differentials of Williams, five with the system of Somé et al., and 10 with the European Clubroot Differential (ECD) set. However, based on a threshold of 50%, there were five pathotypes according to the evaluation system by Williams, four based on the differentials of Somé et al. and 8 with the ECD set. Changing of the thresholds led to the reclassification of some pathotypes. Pathotypes 7 by Williams was the most frequent in both thresholds. High amounts of pathogen DNA were found in many of the field soils analysed by quantitative PCR.
Experiments with P. brassicae-resistant cultivars of winter oilseed rape were conducted in an infested field and greenhouse. In the greenhouse, six resistant cultivars were grown in infested soil collected from various fields in the Czech Republic and assessed for index of disease (ID %). The best results bring cultivar Mentor (2+- 0.7 %) closely followed by cultivar SY Alister (5+-1.1 %), the highest ID had cultivar CHW 241 (30+-3.8%). In the field experiment, seven resistant cultivars were grown, and disease development was monitored monthly. The lowest index of disease brought cultivar Andromeda (3+- 0.8 %) and PT 235 (4+-1.5 %), the highest ID has cultivar CWH 241(46 +- 6.5 %) in the first season and in the second season any cultivar achieved 25 % ID. Yields were measured at the end of the cropping season. The highest yield was achieved by cultivar SY Alister (6.1 t/ha) in the first season and cultivar PT 242 (5.03 t/ha) in the second season. The inoculum level was measured across the field by (qPCR), and a map of the infestation was created. The highest spore concentration was found on the field entrance. Collectively, the information obtained on the effectiveness of host resistance and pathogenic diversity of P. brassicae populations from the Czech Republic may help to more effectively manage clubroot in this country.
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Hydrodynamic mixing of water-ask mixture in vessel
Holub, Přemysl ; Franc, Zdeněk (referee) ; Habán, Vladimír (advisor)
Master´s thesis Hydrodynamic mixing of water-ash mixture in vessel is interested in describing fluid and solid particles flow in a vessel. The mixing was conducted in cylindrical vessel by a radial nozzle. The goal of the thesis is to describe flow field and places where the most of the particles are descending according to position, depth, flow rate and nozzle orientation in the vessel. An experiment was conducted in order to investigate and document 8 different positions and orientation of the nozzle. Significant changes in flow fields and mixing time were observed. A mathematical model of the vessel with the nozzle was created in Fluent program. Places with the lowest velocities according to the model were in good agreement with places where the most of the solid particles were descending.
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