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Dynamic viscosity of electroinsulating liquids
Míka, Petr ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work deals with persepective environmentally friendly electroinsulating liquids. Important properties of currently used electroinsulating liquids are listed. Physical nature of viscosity of liquids and its temperature dependance are described and methods of its measuring are listed. Also temperature dependance of density is described from physical point of view. Measurement of density and of temperature dependance of viscosity of chosen vegetable and mineral oils was performed. On the basis of this measurement was calulated the activation energy of these samples. Two methods of dynamic viscosity measurement were used for some samples.
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Effects of climatic conditions on the properties of butadiene oligomers
Baťa, David ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
The bachelor thesis is conversant of monitoring dielectric material properties in AC electric field. The electrical properties of variety liquid oligobutadiens includes are studying in their practical applications. Experimentally there are verified and analyzed influences of the climatic factors especially temperature and ultraviolet radiation on the frequency dependencies of complex permittivity parts with respect to present various functional groups in oligobutadiene chains.
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Design of measurement unit for analysis of surface materials properties
Kratochvíl, Robert ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
The thesis deals with the application of laser beams for examination of material properties. The properties being examined are quality of surface finish and transmissivity of materials in the optical portion of the electromagnetic spectrum. A measuring device containing laser diodes as a source of laser beam and photodiodes for evaluation of examined phenomena serves for examination of both properties. Conversion of the signal to digital quantity and its further processing take place in a microcontroller. The data is then sent via a serial bus and a converter to a computer, where it may be saved in a user program and where the user can work with them later. The thesis contains results of reflectivity measurement of a set of metal samples with different surface finish. Transmissivity measurement was applied on a set of optical filters.
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Relative humidity effects on the electrical properties of silicone ruber
Pušec, Daniel ; Polsterová, Helena (referee) ; Frk, Martin (advisor)
At the beginning, this master thesis briefly describes the principle of semiconductors. It states their types, methods of operation, fields of use, and it interprets the manner of semiconductor devices’ passivation. Then it introduces silicones, their properties and usage. Later on, this thesis summerize air humidity theory and materiál moisturing including mathematical interpretation. Next chapter is devoted to basics of dielectric materials’ behavior. And finally, the last part of this thesis estimates charakteristics of passivation materiál, Dow Corning HIPEC Q1-9205 silicone rubber.
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Study of ferroelectric materials
Kos, Lukáš ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work is focused on the study of perovskite ferroelectric materials group and monitoring changes their dielectric parameters in temperature and frequency dependence Is described scrystallographic systems of barium titanate and their influence on material properties. The measured values are mathematically interpreted using the Curie – Weiss law and discussed about the influence of strontium titanite on important dielectric parameters.
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Framework design for automated testing of web sites
Sieber, Lukáš ; Šteffan, Pavel (referee) ; Frk, Martin (advisor)
This master's thesis is based on automated web applications testing with freeware instrument utilization developed under Google code project. It is called Selenium webdriver and become very popular during last years. Selenium webdriver is frequently used for web pages automation. Indisputable advantages of this solution are low entry cost, selenium is broadly used and also live community around that instrument with many useful informations. Main goal of this thesis is creation of automation framework created by Java programming language. This final framework will integrate Selenium webdriver and guarantee easy creation of testing scenarios. Because of this goal is placed mainly on separation of web page programmatic description and description of testing scenario.
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Modeling and approximation of absorption phenomena in dielectric materials
Raška, Jiří ; Polsterová, Helena (referee) ; Frk, Martin (advisor)
This thesis focuses on the polarization effects, that go on in the dielectric materials. It deals with physical and mathematical description of absorption effects. An important part of the thesis is a program environment, that is made by using programming language C++, which might be used for illustrative graphical displaying of physical laws of absorption effects in dielectric materials and for control of meters used for absorption current in dielectric materials measurement. This program can compute selected material constants from measured absorption currents. The proram enviroment enables creation of measurement protocol according to the norm ČSN IEC 93.
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