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Aging and possibilities of its removal
Kolena, Robert ; Šlais, Miroslav (referee) ; Podaný, Kamil (advisor)
Thesis elaborates on current study of aging issues and describes its development caused by interstitial nitrogen and carbon atoms. It also points out how properties of materials are influenced. There are several removal options. The first one is heat treatment consisting of recovery and recrystallization annealing, the second one is binding of nitrogen atoms to chemical elements with higher affinity and third one is rolling with realization of small plastic deformation. Overall assessment and practical examples are also added.
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Testing of Surge Arresters
Jeřábek, Lukáš ; Paar, Martin (referee) ; Krbal, Michal (advisor)
This bachelor's thesis is devoted to metal oxide surge arresters. After historical and theoretical introduction, which explains their principles and describes their characteristical properties, analysis of the standard IEC 60099-4 and testing according to the standard with focus on the type tests follows. This chapter is also amended with review of the standard's imperfections and with its most probable future development. The work concludes with a market survey, a review of the largest manufacturers and a comparison of their products.
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Diagnostics of electroinsulating liquids properties
Makówka, Tomasz ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
The diploma thesis deals with the liquid insulators, their properties and their use in the electrical industry. The general aim is to study the physical essence of the dynamic viscosity, the electric conductivity and the diagnostic methods for monitoring these variables. The experimental part contains measuring the dynamic viscosity and the electric conductivity of the mineral transformer oils ESTO BNX, RENOLIN ELTEC and the biodegradable oil MIDEL 7131 during the degradation. The Walden rule is applied on measured results.
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Rheological properties of binders
Hotař, Petr ; Fišer,, Jiří (referee) ; Kudrna, Jan (advisor)
The comparison of rheological properties (complex shear modulus and phase angle and dynamic viscosity) of four paving bitumens and two polymer modified bitumens is performed in this diploma thesis. Furthermore, the empirical tests (needle penetration and softening point) were determined on these binders. Effect of asphalt binders aging was modeled using RTFOT test and modified RTFOT test (3 x RTFOT).
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Permanent deformation on asphalt mixtures
Bambulová, Lucie ; Coufalík, Pavel (referee) ; Hýzl, Petr (advisor)
The bachelor thesis deals with a description of the laboratory properties of aged bituminous binders in relation to permanent deformation. The theoretical part deals with the empirical tests: needle penetration and softening point. There is also explained the procedure and the principle of the MSCR test. In the practical part are evaluated the properties of fifteen tested bituminous binders and based on the results are made two plates which are tested to permanent deformation.
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The use DC electrical method in diagnostics of insulating materials
Volf, Michal ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
In this work describe to the Dielectric relaxation spectroscopy for the evaluation of the actual status of insulation systém. The used methods of quantifying the dielectric response in time domain are polarization-depolarization current and recovery voltage measurement and in frequency domain the loss factor and the complex capacitance measurement. Influence of thermal ageing and temperature dependences of charge and dischage currents are observed.
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Design of high voltage source for electrical ageing of insulating mater
Příborský, Václav ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
Target of this thesis is analyse problems of dielectric materials ageing and environment characteristic applied by ageing process. Types of electric stress are comparing in this work, when and how they are working and how to eleminate them. Next aim is design the high voltage sinus transformer as source for measuring of electric stress and ageing dielectric materials. There is discuss about computer control and collecting of the output datas. In the end is source testing by practical measurement of some dielectric samples.
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Influence of the temperature on the preparing of asphalt mixtures with higher amount of RAP
Škrobáček, Petr ; Koudelka, Tomáš (referee) ; Varaus, Michal (advisor)
This bachelor thesis is focused on the preparation of the reclaimed asphalt pavement for production of asphalt mixtures. In the thesis there is investigated the effect of the temperature of preparation the reclaimed asphalt pavement on the characteristic of the bitumen content. In the theoretical part there is described bitumen as such and reclaimed asphalt pavement. In the practical part there is described the preparation of the material for laboratory tests. The next step is the extraction and distillation of bitumen. These bitumens are tested according to depredescribed tests: ‘Determination of needle penetration (ČSN EN 1426)’, ‘The softening point (ČSN EN 1427)’ and ‘Dynamic shear rheometer’. In the last section of this bachelor thesis there is a comparison of the individual properties of the rendered bitumen of the asphalt mixtures of reclaimed asphalt pavement, with the aim of evaluating temperatures of preheating and degradation of the bitumen on the final characteristic of the asphalt mixtures witch higher quantity reclaimed asphalt pavement. The measured values of the temperature for preparation of reclaimed asphalt pavement shows that the temperature of the asphalt mixture before production has a significant effect on the characteristics of the bitumen, which is included in the reclaimed asphalt pavement. There is evident the difference between specimen of the asphalt mixture of reclaimed asphalt pavement and the reclaimed asphalt pavement. It is visible only from the bottom layer too.
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Influence of aging on sandwich materials properties
Smékal, Aleš ; Löffelmann, František (referee) ; Klement, Josef (advisor)
The first part of the master’s thesis deals with sandwich materials. Starting with composition of parts which the sandwich panel is made of. The thesis continues with loading distribution and testing of entire sandwich panel. The impact of environment is considered as well. The second part is its goal – determine degradation of the properties of sandwich panels with metal sheets and core after 15 years aging in the common atmosphere and aging in moistheat and salt environment by experiment.
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The effect of production parameters on the plasticity of structural steel
Brabec, Martin ; Podaný, Kamil (referee) ; Peterková, Eva (advisor)
The master thesis deals with the influence of heat treatment and storage time on microstructure and mechanical properties of 26MnB5 steel, which is used in the production of tubular components in the quenched and tempered state. The objective was to increase the plasticity of the steel by the definition of new process parameters of the induction heat treatment line. New tempering diagrams of 26MnB5 steel for two various speeds of the heat treatment line were established and used to determine new tempering temperature and speed of the heat treatment line. Observation of the influence of storage time on mechanical properties of the steel did not reveal that it is liable to ageing.
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