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Numerical simulation of crack propagation in ceramic composites in 3D
Svoboda, Josef ; Horníková, Jana (referee) ; Majer, Zdeněk (advisor)
The strength of materials such as glass and ceramics can be influenced by the environment (stress corrosion). Under applied stress defects (cracks) can grow sub-critically below fracture toughness K_Ic. The aim of this work was to develop a three-dimensional finite-element model to analyze the subcritical crack growth behavior of ceramic-based particulate composites. The maximum tangential stress criterion (MTS) was used to predict the direction of the crack propagation in the framework of linear elastic fracture mechanics. The modeled material was a Low Temperature Co-fired Ceramics (LTCC), containing alumina particles embedded in a glass matrix. The main aim of this work was to develop a 3D model describing the crack growth. Conclusions from this work can contribute to a better understanding of subcritical crack propagation in particle composites.
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Heat transfer by thermal radiation
Budovec, Michal ; Svoboda, Josef (referee) ; Foral, Štěpán (advisor)
This bachelor’s thesis deals with heat transfer, specifically with thermal radiation heat transfer by convection. The work is divided into theoretical part and calculations. The theoretical part describes basic thermomechanical notions and all kinds of heat transfer with the emphasis on heat transfer by radiation with convection. Heat conduction chapter describes the basic types of heat conduction. In chapter Heat transfer by convection are given criterion equations and examples for determining dimensionless numbers. Radiation heat transfer chapter focuses on heat transfer between two bodies and the radiation factor. With this equations and dimensionless numbers are quantifying variables in the calculation part. In the theoretical part is wrought calculation for a given case of heat transfer in the air and vacuum. The calculation is experimentally verified, from which is wrought protocol with the measurement and comparison with calculation and measurement in the air and vacuum.
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Alternative sources of nuclear energy
Svoboda, Josef ; Zlámal, Ondřej (referee) ; Katovský, Karel (advisor)
In places where it is not possible to use conventional production and distribution of energy, autonomous sources take over. Most of autonomous sources use solar energy, wind energy and other renewable resources. For applications such as special missions into outer space the usage of conventional sources is not possible. Except for powering special satellites, unconventional nuclear sources are also used in autonomous unmanned objects located in distanced areas with extreme natural conditions. It is also used in unusual propulsions of ground, water and air machine. These vehicles are for example pacemaker powered by radioisotope source, submarines, aircrafts and other vehicles supplied by nuclear reactor of unconventional conception. In this bachelor thesis there are globally summarized questions connected with unconventional sources of nuclear energy with detailed description of chosen parts. This work is concerned with finding more efficient machinery for conversion of heat energy supplied by radioisotope decay to electric energy.
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Comparison of the price shares of individual constructions in the total price stated in the price schedule and detrmined by the item budget
Lorencová, Andrea ; Svoboda, Josef (referee) ; Kosová, Jaroslava (advisor)
The topic of this diploma thesis is a comparasion of the price shares of individual constructions in the total price stated in the price schedule and determined by the item budget. The diploma thesis says and describes cost methods of valuation of building facilities and family houses at the outset. There is contained a procedure for determinating the price shares of construction and equipment and theirs adjustment in the next text. According to the chosen metodology are determined the price shares of constructions and equipments based on the item budget. This way determined the price shares of constructions and equipments are compared with the price shares of construcions and equipments determined by Decree No. 441/2013 Coll. The aim of diploma thesis is to determine if the price shares of constructions and equipments based on the item budget correspond to the price shares of constructions and equipments in the price schedule.
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Possibilities of thorium utilization in current NPPs
Svoboda, Josef ; Praze, Jan Prehradný, ÚE FS ČVUT v (referee) ; Katovský, Karel (advisor)
Nuclear power plants provide about 11 percent of the world's electricity production. For fission process is uranium fuels used with varying percentage of enrichment 235U for most of nuclear reactors. Uranium reserves are reducing and their mining cost increases. Therefore, the thorium fuel is discussed as revolution fuel for current and future nuclear power plants. This diploma thesis deals with possibility of thorium fuel utilization at various types of nuclear reactors with a focus on light water reactors. The practical part of the thesis is focused on simulation and calculations of various uranium dioxide and thorium dioxide layers at the fuel rods. Model of WWER 440 reactor was developed for the calculations with the addition of thorium fuel. The model simulates burning out of fuel for 5 years, with monitoring of fuel behavior and tracking changes of each material. The thesis tries to define the suitable ratio and parameters of layers combination of uranium and thorium fuel. For these ratios and parameters the thesis tries to give sufficient amount of computational analyzes.
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Meteorological Station with Remote Access
Svoboda, Josef ; Číž, Radim (referee) ; Sysel, Petr (advisor)
This thesis discusses design and realization of air temperature, pressure and relative humidity measuring device, transmission of measured data over internet and their presentation on a web site. First chapter introduces reader into principles of measuring air temperature, pressure and relative humidity and various types of sensors used for measuring . Next, the conception of designed system is described. Designed system must accomplish tasks from reading raw data from the sensor up to thein graphical presentation to the internet user. Second and third chapter describes hardware and software design of air temperature, pressure and relative humidity measuring unit. In next part one can find description of software used to transmit measured data over internet and software for generating web pages which are shown to users. The work is revieved in the final part of this thesis.
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Direct digital frequency synthesizer
Svoboda, Josef ; Šebesta, Jiří (referee) ; Kasal, Miroslav (advisor)
Direct Digital Frequency Synthesis (DDFS) is a method of producing an analog waveform, usually a sine wave, by generating a time varying signal in digital form a then performing a digital to analog conversion. Because operations within a DDFS device are primarily digital, it can offer fast switching between output frequencies, fine frequency resolution and operation over a broad spectrum of frequencies.
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Stress and deformation analysis of railway bridge over the Odra River
Svoboda, Josef ; Profant, Tomáš (referee) ; Fuis, Vladimír (advisor)
This bachelor thesis deals with strain, stress and deformation analysis of the planar truss bridge construction. The aim is to determined the size of axial forces for statically determinate system and then making construction changes to reduce axial stresses in the individual beams in the structure. This structural modification becomes statically indeterminate structure. To solve this problem we consider different positions of the train at the bridge. The obtained values we can use to assess stress and deformation of the structure and the analytical results will be compared with the results obtained using the finite element method.
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