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Electrical properties analysis of epoxy resins with various fillers
Horák, Luděk ; Kazelle, Jiří (referee) ; Frk, Martin (advisor)
Presented bachelor thesis is focused on studying electroinsulating epoxy resin-based sealings. It describes the chemical composition, production, properties and measuring methods of basic electric quantities of these materials. This work also embodies a preparation of composite epoxy resin samples with different kinds of micro-ground siliceous sand as a filling. The samples given are measured on the temperature dependency of relative permitivity, dissipation factor and inner resistivity.
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Electrical properties of anisotropic dielectric material
Příkazský, David ; Štumpf, Martin (referee) ; Vélim, Jan (advisor)
This work is focused on finding the dielectric properties of unknown material. Especially those we affect the behavior of electrical energy in the material, this feature describes parameter permittivity of material. In this work will be used multiple methods to determine values of permittivity. These measured values of different measurement methods will subsequently compared to each other. Then be discussed in the conclusion reached values and comparing used measurement methods.
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Analysis of temperature and humidity processes in intensive vegetation roof layers
Sukopová, Dáša ; Solař, Jaroslav (referee) ; Mohelníková, Jitka (referee) ; Vlček, Milan (advisor)
The presented dissertation deals with the analysis of temperature and humidity processes taking place in the layers of an intensive vegetation roof with a larger layer of soil - the roof garden. The aim of my dissertation is to provide more accurate information for the design of the roof covering using the properties and benefits of the vegetation layer of the roof garden. One of the most important advantages of roof gardens is the cooling effect of the vegetation formation in the hot summer season. The work also deals with the idea of wider use of roof gardens for the so-called rooftop farming, which is becoming more and more popular in the world. Otherwise, unused roof areas can make up for the lack of areas for gardens, which are especially lacking in big cities.
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Computer modelling of mixture formulas of composite materials
Matoušek, Jiří ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
Submitted work engage in modelling of progressions of dielectric variables and aplication of mixture formulas for solution of composite materials in dependency on frequency. Theoretical part engage in theory of dielectric materials and composite materials and contains summary of basic mixture formulas. A part of work is programm which can be used in education. It allows modelling of permitivity, loss factor and loss number in dependency on frequency and Cole-Cole circle diagram in materials. In mixtures modelling of Maxwell´s, Bőttcher´s and Lichtenecker´s mixture formulas.
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Minimizing errors in measuring ultra low currents
Maule, Radek ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
This work describes the methodology of measuring ultra low currents of the order of 10-8-10-14 [A] and the errors that arise during the measurement. This work is focused on electrical conductivity of insulation materials and interfaces electrode - dielectric during charging and discharging of the sample which is located in the ideal workplace.
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Study of the dielectric properties of perovskite crystals
Mlčkovová, Hana ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
The presented diploma thesis deals with the preparation of perovskite single crystals by inverse thermal crystallization and subsequent study of the basic properties of these hybrid organic-inorganic materials that can be used in various optoelectronic (photodetectors, transistors, lasers, LEDs) or photovoltaic applications. Their behavior in the electric field was studied by impedance spectroscopy. Impedance and capacitance-voltage (C-V) characteristics (frequency dependences) were measured in the dark and in the light. From the impedance dependences for measurements at 0 V voltage in the dark, the equivalent circuit was modeled and its parameters and dielectric constant were determined. From the C-V dependence, Mott-Schottky analysis determined the parameters – "flat-band" potential U_"fb" and charge carrier density N_"C-V" , the parameter – the so-called Warburg coefficient was found, which together with the parameter N_"C-V" was used to calculate the diffusion coefficient D.
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Inorganic fillers effect on electrical properties of the epoxy resins
Doležel, Tomáš ; Jirák, Josef (referee) ; Frk, Martin (advisor)
This thesis deals with problems of electrical insulation materials based on epoxy composites used in the electronics industry. This thesis is divided into theoretical part focused on composite materials, their technological processing and diagnostics. It also describes dielectric materials, their properties and events taking place in their structure. The experimental section describes the measurement of electrical properties of samples of electrical insulating materials with different types of fillers.
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Dielectric Properties of Vegetable Oils for Electrical Engineering
Spohner, Milan ; Mejzlík,, Miroslav (referee) ; Mentlík, Václav (referee) ; Liedermann, Karel (advisor)
The dissertation thesis deals with the analysis of prospective environmentally compatible electrical insulating fluids for electrical engineering in relation to their chemical structure. The thesis starts with the overview of the current state of the art and of the latest trends in the use of synthetic and biodegradable natural oils. In the experimental part were studied these oils: mineral oils, rapeseed oil, sunflower oils, soybean oil, methyl oleate, peanut oil, MCT oil, castor oil and other. Dielectric properties were measured using LRC meter Agilent 4980A including dielectric liquid test fixture Agilent 16452A and also by the Novocontrol Alpha-A analyzer. Electrical properties are presented in the frequency range 10 mHz – 1 MHz range in the temperature interval 253 K to 363 K. The work goes on with the study of the suitability of individual oils for lower temperature, including the impact of the chemical structure and formulation on electrical properties.
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Energy dispersive X-ray spectroscopy of doped PVDF fibers
Smejkalová, Tereza ; Papež, Nikola (referee) ; Sobola, Dinara (advisor)
Tato diplomová práce zkoumá flexibilní materiál k produkci elektřiny založený na piezoelektrickém polymeru Polyvinylidenfluorid (PVDF). Inkorporací piezoaktivní keramiky lze vlastnosti piezoelektrického polymeru PVDF významně zlepšit a převést na užitečnou elektrickou energii. PVDF byl vytvořen elektrostatickým zvlákňováním do vláken o tloušťce 1,5-0,3 µm a poté studován různými analytickými metodami. Tato práce nabízí popis elektrostatického zvlákňování, přípravu vzorků a teoretický úvod do analytických metod, kterým byly vzorky podrobeny. Morfologie a distribuce nanostrukturované keramiky do polymerní matrice PVDF byla pozorována použitím skenovací elektronové mikroskopie (SEM) a energiově disperzní spektroskopie (EDX). Pro tvorbu fáze a podrobné fázové složení byly vzorky charakterizovány infračervenou spektroskopií s Fourierovou transformací (FTIR). Práce také obsahuje analýzu s použitím Ramanovy spektroskopie, metody používané k identifikaci a porovnání chemických sloučenin. Elektrické vlastnosti byly studovány dielektrickou spektroskopií a je poskytnuta korelace se složením. Jednotlivé komponenty dotovaných vláken jsou charakterizovány a vyhodnocovány v souvislosti s jejich budoucím využitím v senzorech.
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