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Thermal degradation of alternative electrical insulating liquids
Vodička, Tomáš ; Kazelle, Jiří (referee) ; Frk, Martin (advisor)
This thesis deals with alternative thermal degradation of electrical insulating liquids. The theoretical part describes the current state of the problem, electrical insulating liquids, their classification and types. There are described properties of electrical insulating liquids, their models of aging and diagnostic methods in accordance with the appropriate standards. In the practical part are chosen by representatives of alternative electrical insulating liquids and there are determined their dielectric characteristics in the initial state. According to the measured values is chosen five candidates for which it is designed and implemented an accelerated degradation test. During the test are measured dielectric parameters of the selected oils. Measured dependencies are mathematically approximated. In conclusion, the results are compared and physically interpreted in view of oxidation stability.
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Joint sealings of concrete pavements
Doseděl, Jan ; Hýzl, Petr (referee) ; Stehlík, Dušan (advisor)
The findings related to issues of joint sealings of concrete pavements are summarized in this bachelor thesis. The main part of this thesis deals with experimental testing of modified asphalt binder. This asphalt binder was tested at the beginning and at the end of fatigue. The samples of asphalt bitumen were tested by the method of ring and ball, determinativ of needle penetration, elastic recovery and resilince.
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Recycling of bituminous binders by using recycling agents
Koudelka, Tomáš ; Komačka,, Jozef (referee) ; Dašek, Ondřej (referee) ; Varaus, Michal (advisor)
Increasing the content of Reclaimed Asphalt in hot asphalt mixtures is one of the current issues in road construction, to which society's attention is paid. The higher content of Reclaimed Asphalt brings higher technological demands not only for the production of asphalt mixture plants, but also for the handling of materials in general. The benefit for higher demands on asphalt mixture production is the subsequent reduction of the environmental burden associated with the construction of road infrastructure caused by the mining industry and use of natural resources. The dissertation is focused on studying recycling agents which are used in the production of asphalt mixtures containing Reclaimed Asphalt. Emphasis is put on comparing the properties of recycled binders with paving bitumen and binders from Reclaimed Asphalts whereas the effect of repeated recycling is taken into account. A large part of the thesis is devoted to the design of the optimal dosage of recycling agents. Certain findings were used to draw a methodology describing the design of dosing of these agents. At the same time, the properties and behaviour of the recycling agents themselves were evaluated.
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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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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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WETTABILITY OF PCB SURFACE FINISHES
Minář, Jan ; Jana, Toulová (referee) ; Starý, Jiří (advisor)
This bachelor’s thesis with measuring of wetting characteristics by the wetting balance method for samples of different surface finishes from the firm Gatema. It deals with influence of the isothermal aging and reflow processes on wetting characteristics of surface finishes ENIG, HAL and immersion tin. The influence of intermetallic layer on the overall wettability is studied in case of the surface finish of immersion tin. Also deals with the wettability of the nickel layer, after stripped off gold, in case of the surface finish of ENIG.
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Senior citizens home Sokolnice
Vávra, Vít ; Šindlar, Jiljí (referee) ; Marek, Jiří (advisor)
The area of the former barracks lies near Sokolnice falling into the periphery of Brno. It is a picturesque village that has a rich history. The barracks are located on a hill called Stará hora, there are several cadastral areas. Near the building, we can find a radar that manages the nearby Brno airport, or the Peace Mound built on the Prateck Hill, soldiers fall to remembrance. The design principle was based on the given operation and its related functions. Dining room, rehabilitation, barber, pedicure, buffet and, last but not least, a multifunctional hall with a small library. The destruction of the unnecessary transformer station and the replenishment of the mass was a logical solution to the situation. It is an assembled reinforced concrete frame 8x8m. Inside the half-block we find a terrace with a pool, which is trying to create a specific microclimate and humidify the surroundings. The pool also serves as a retention tank and the house effectively manages rainwater. Within the lifetime, because of the corrosion of reinforced concrete and the unclear condition of the structure, I designed the exterior cladding to demolish and build a new cladding, a brick made of ceramic blocks. The house is designed in a minimalist spirit and cooperates with the greenery in its surroundings. Especially in long-distance views of integration into the landscape, this greenery is valued. The spirit of place in heavy air bears a strange whiff of dragging death that, when thinking about the history of a place, froze and freezes ... so perhaps while resting before the last journey ... that house discourages and breathes a little life into dying ...
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Kinetics of hydrophobic organic compounds uptake in the earthworm Eisenia andrei in soils with different content of organic carbon
Šmídová, Klára ; Zlámalová Gargošová, Helena (referee) ; Čáslavský, Josef (advisor)
This thesis is concerned with the fate of hydrophobic organic pollutants (HOCs) in soil. The theoretical part summarizes the current knowledge about bioavailability, factors influencing the bioavailability and methods for its measurement. Attention is paid to the organic carbon content, which is considered to be one of the key factors and to the influence of microorganisms that can degrade or interact with the substances, thus changing their bioavailable ratio. The practical part of the thesis uses bioaccumulation test with earthworm Eisenia andrei for evaluating the uptake kinetics HOCs in three soils with different organic carbon content. Soils were laboratory contaminated with mixtures of selected HOCs (phenanthrene, pyrene, lindane, p,p'-DDT and PCB 153) and the concentrations of substances in these soils were followed for 217 days. Subsequently, bioaccumulation test was conducted; earthworms were exposed from one to twenty-one days. The collected data were used to model uptake kinetics curves for individual substances. Peak-shaped bioaccumulation were found for pyrene, for lindane a steady-state concentration during exposure was observed, whereas for p,p'-DDT and PCB 153 growing concentrations after twenty days of exposure were detected. The reason for the different behavior of the substances was probably their diverse sorption on the organic material, which together with the different speed of elimination influenced final concentration in earthworms. Phenanthrene was not detected in some samples and therefore the modeling of uptake kinetics was not possible.
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