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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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Properties of liquids based on organic esters
Toulová, Jana ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This master's thesis deals with the electrical insulation fluids used in electronics industry. The analysis of the current state of research and innovations in modern, biodegradable fluids in terms of their use as diagnostics. It is described by the physical nature of polarization and conductivity mechanisms, which are applied in liquids. It was compiled automated workstation for monitoring components of the complex permittivity over a wide temperature range. In the experimental part we analyzed the behavior of liquids selected alternative based on natural esters when exposed to an alternating electric field at various temperatures. Evaluated results are compared with values for conventional mineral oil.
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Computer modelling of courses of complex permittivity
Frybert, Jan ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
The aim of this work was to create the program for modelling of frequencies courses of complex permittivity parts according to the basic empirical functions, which are described distribution of relaxation time. The main attention is concentrated on the influence of particular parameters on the courses of real and imaginary parts of complex permittivity. Whole program is written in Borland Builder C++.
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Analysis of degradation mechanisms oligobutadienes
Baťa, David ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work deals with the studies of liquid oligobutadiens properties in AC electric field by dielectric relaxation spectroscopy method. The current issue in the diagnosis of oligomeric and polymeric materials during the activity of various degradation factors and options of their alleviation and suppression was studied. The existing apparatus is modified for monitoring possibilities of polymeric materials during the action of various degradation and operational factors. Effect of climatic factors are experimentally investigated, especially UV radiation and temperature on the course of the frequency dependence of complex permittivity components with respect to the different composition and length of the polymer chain.
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Analysis of multistress ageing on dielectric spectras of materials
Kučera, Miroslav ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
Diploma thesis treat of effect of thermal, electrical and combined (thermal electrical) stress on electrical characteristics of insulation material ISONOM NMN which is used as a slot insulation in electric motors. To monitor the stress is used the method of dielectric relaxation spectroscopy. Under examinations are the resultant dielectric spectra which constitute the frequency dependencies of components of complex permitivity. Compared are the effects of particular stresses on dielectric spectra of surveyed insulative material.
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Influence of curing parameters on the properties of insulating varnishes
Paščinský, Jiří ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
The bachelor thesis submitted deals with properties of electro-insulating lacquer hardenable by ultraviolent radiation and temperature. Within the theoretical part a summary of electro-insulating lacquers used in electrotechnics has been elaborated. Chemical changes that take place in this material group have been described during hardening process. A method of dielectric relaxation spectroscopy specifically focused on mathematic and physical description of polarisation and conductive mechanisms taking place in the structure of the given material has been closely studied. In the experimental part a workplace for hardening and long-term exposition of lacquered samples during simultaneous effect of various climatic elements has been designed and built. The selected electric and mechanical properties have been monitored on three sets of experimental samples prepared by means of different methodical procedures. The results gained have been mathematically evaluated and physically interpreted in term of methodical procedure of hardening and different temperature of measurement.
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Dielectric Properties of Thermoplastic Materials with Ground Mica
Fiala, Ivo ; Havlíček, Svatopluk (referee) ; Polsterová, Helena (advisor)
The subject of this thesis are composite materials, measuring of their dielectric qualities, particularly of the polyamide and the polyamide filled with various weight percentage of the ground mica. The essential intent of the thesis is to determine the measuring methodology and respective measurement of the basic dielectrical quantities of materials, as are loss factor and the complex permitivity components. The measuring should be done for various temperature and humidity combinations. The thesic contains the physical explanation of measured dependences.
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