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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Nejistoty měření dynamické viskozity / Uncertainties of measurements of the dynamic viscosity

Januš, Petr January 2012 (has links)
The thesis is deal with measuring the temperature dependence of dynamic viscosity and the calculation of measurement uncertainties. The thesis writes up the physical nature of viscosity and rheological properties. Next it is write up an overview of possible methods for measuring viscosity of liquids and overview of methods for measuring the density of liquids. An important chapter is the statistical evaluation of measured data represented mainly measurement uncertainties. In the practical part of the work is done workplace for measure the temperature dependence of dynamic viscosity. It is used two methods of measuring viscosity of liquids and two samples of liquids. Finally is done statistical evaluations of measurement. Based on the calculated measurement uncertainty measurement methods are compared.
92

Fuzzy systémy s netradičními antecedenty fuzzy pravidel / Fuzzy systems with non-traditional antecedents of fuzzy rules

Klapil, Ondřej January 2015 (has links)
The aim of this work is to introduce a new type of fuzzy system AnYa. This system, unlike the classical fuzzy systems Takagi-Sugeno and Mamdani, uses a type of antecendent based on real data distribution. As part of the work there will be mentioned system programmed and its functionality will be verified on testing data.
93

Analýza reologických vlastností teplonosných kapalin / Rheological properties analysis of heat transfer fluids

Neradil, Petr January 2016 (has links)
This master thesis deals with the issue of heat transfer fluids for solar thermal system. It discusses the different types of solar systems and their use. It also describes the different types of heat-transfer fluids for solar thermal systems and analyzes the basic chemical composition of commercially available heat-transfer fluids. There are described the properties of these fluids and methods for measuring certain properties. The practical part deals with measuring the temperature dependence of density and dynamic viscosity of alternative and commercially available heat-transfer fluids, determining the freezing point and compares the results.
94

Závislost rychlosti růstu pstruha obecného Salmo trutta na populační hustotě v oligotrofních tocích / Density dependent growth of brown trout Salmo trutta in oligotrophic streams

Závorka, Libor January 2011 (has links)
This thesis deals with the influence of population density on the growth of brown trout Salmo trutta. The research was carried out in the Šumava National Park in the river basins of two oligotrophic streams, the Vydra and the Křemelná. Data has been collected between years 2005 and 2010, every spring and autumn. Fish were caught via electrofishing and the length and weight of each individual were measured. Every individual caught was marked in a unique way. A few samples of scales were taken from some of them. The scales were fixed into laboratory slides, scanned and measured by graphic software. According to the differences between annual lamellas density, the age and the annual growth of individual's body length were estimated. Thanks to these results a negative relationship between the individuals' of age 1+ growth rate and the population density was confirmed. The importance of this thesis is mainly in comparing the influence of different spatial and time definitions of population on this relationship. The influence of the population density in spring (the initial time of the growth period) was proved to be essential for the growth rate. This fact suggests the importance of compensation growth intensity after the long period of winter for individual's general growth under conditions provided by...
95

Ventilačně-respirační změny a difuze plynů v simulované sněhové lavině / Ventilation-respiratory changes and diffusion of gases in the simulated snow avalanche

Sýkora, Karel January 2016 (has links)
Title: Ventilation - respiratory changes and diffusion of gases in the simulated snow avalanche. Goals: The aim of this study was to investigate different ventilation-respiratory parameters with breathing into the simulated snow avalanche with and without any air pockets. Method: An intervention randomized double blind crossover study was conducted on 12 male students of Military Department at the Faculty of Physical Education and Sports of Charles University. The study was realized in the Krkonoše Mountains in the period January 14 - 18th, 2013 at an altitude of 762 m above sea level. Each volunteer underwent two phases of the experiment in a random order: 1st phase "AP"- breathing into the snow with a 1 L air pocket, and 2nd phase "NP"- breathing into the snow with no air pocket. Physiological parameters, especially fractions of O2 and CO2 in the airways and work of breathing (WoB) expressed as Pressure- Time Product (PTP) were recorded continuously. Results: The presence of the air pockets and size has an important role in the survival of buried avalanche victims. The finding of this study is that it is possible to breath in the avalanche snow even with no air pocket (0 L), but breathing under this condition is associated with significantly increased work of breathing. The limiting factor in no...
96

Hustotní a elektrostatické vlastnosti vody a jejich využití v termodynamice vodných specií a rozpustnosti minerálů za vysokých teplot a tlaků / Volumetric and electrostatic properties of water and their application to aqueous thermodynamics and mineral solubility at high temperatures and pressures

Hanková, Barbora January 2018 (has links)
Hydrothermal fluids are important mass and heat transfer agents in the Earth's crust and mantle. Aside from their transport role, the aqueous fluids act as reactants or products in rock environment during diverse processes ranging from partial melting, magmatic and metamorphic devolatilization. This study evaluates the effect of equations of state and thermodynamic data for aqueous species on prediction of mineral solubility in aqueous fluids at high temperatures and pressures employing the Helgeson-Kirkham-Flowers model (HKF). These calculations require: (i) volumetric properties of water; (ii) dielectric properties of water; (iii) aqueous species thermodynamic properties. A comparison of ten equations of state against the IAPWS scientific standard reveals that volumetric properties of water up to 1200 řC and 50 kbar are predicted within 5 %, except at low pressure (below 2 kbar), temperatures higher than 1000 řC, and the liquid-vapor equilibrium curve, particularly in the proximity of the critical point of water. The deviations of volumetric and electrostatic properties of water propagate into the mineral solubility calculations. For quartz and corundum these deviations lead to discrepancy in mineral solubility of up to half an order of magnitude for molal concentrations. These discrepancies...
97

Stanovení teplotní závislosti motorových olejů pro zemědělskou techniku

Přibyl, Patrik January 2018 (has links)
This diploma thesis deals with determination of temperature dependence of motor oils of agricultural technology. Five farm machines were selected and the oil used for servicing the engine oil was a sample of the used oil and a sample of the new oil. For both samples, their physical and mechanical properties were measured in relation to temperature. The first part of the thesis deals with the description of the engine oil functions, the production technology, the classification and the physical properties engine oils. The second part deals with description of measurement methodology and description of measuring machines in the first half of the year and in the second half the results of the measurement are interpreted and discussed
98

Využití recyklovaného dřeva ve výrobě dřevotřískových desek

Havelková, Hana January 2017 (has links)
The research was partially inspired by three-layer particle boards with a density of approximately 600 kg/m3 in various variants. The recycled wood was used for manufacture these particleboards in different portion: 10, 30, 60 and 90%. Of each variant were produced two boards of dimensions 600 x 600 x 12 mm, altogether eight boards. Laboratory produced chips of recycled material and chips of pure wood were separated in the surface and core layer. The chips were separated by sieve analysis. Subsequently they were prepared and processed into boards with different amounts of recycled wood. Also, two boards were pressed from a control chips from Kronospan Jihlava that used in the production mixed chips with recycled wood and which provided a reference desks of industrial production for this research too. The moisture content, density, swelling properties, bending strength, modulus of elasticity and tensile strength were determined on the ten boards produced in laboratories Mendel University in Útěchov and on four boards from Kronospan. Properties were compared with control and reference particleboards as well as between each tested group using Analysis of variance (ANOVA) and descriptive statistics.
99

Hustotní profil a jeho vliv na vlastnosti třískových desek

Matyáš, Michal January 2017 (has links)
The goal of this thesis is to determine properties of manufactured particleboards with different percent content of recycled wood. The objective was to determine density values, thickness swelling, moisture content, internal bonding, bending properties and vertical density profile of particleboards. The research question was to report the effect of different percent content of recycled wood on final properties of particleboard. The own method was established and various particleboards produced. The properties of materials were tested according to EN standards and by descriptive statistics, analysis of variance (ANOVA) and linear regression evaluated. In summary in research it was observed that percent content of recycled wood has little impact on final properties of particleboard, although there were several factors which may have affected these results. These factors are described in this thesis.
100

Ventilačně-respirační změny a difuze plynů v simulované sněhové lavině / Ventilation-respiratory changes and diffusion of gases in the simulated snow avalanche

Sýkora, Karel January 2016 (has links)
Title: Ventilation - respiratory changes and diffusion of gases in the simulated snow avalanche. Goals: The aim of this study was to investigate different ventilation-respiratory parameters with breathing into the simulated snow avalanche with and without any air pockets. Method: An intervention randomized double blind crossover study was conducted on 12 male students of Military Department at the Faculty of Physical Education and Sports of Charles University. The study was realized in the Krkonoše Mountains in the period January 14 - 18th, 2013 at an altitude of 762 m above sea level. Each volunteer underwent two phases of the experiment in a random order: 1st phase "AP"- breathing into the snow with a 1 L air pocket, and 2nd phase "NP"- breathing into the snow with no air pocket. Physiological parameters, especially fractions of O2 and CO2 in the airways and work of breathing (WoB) expressed as Pressure- Time Product (PTP) were recorded continuously. Results: The presence of the air pockets and size has an important role in the survival of buried avalanche victims. The finding of this study is that it is possible to breath in the avalanche snow even with no air pocket (0 L), but breathing under this condition is associated with significantly increased work of breathing. The limiting factor in no...

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