|
|
MW Converter for SW Receiver
Lejsková, Alena ; Lukeš, Zbyněk (referee) ; Šebesta, Jiří (advisor)
This thesis concerns about the network synthesis of receivers with the demand for conversion of the input signal and a following implementation of assigned converter. At first it introduces the readers with the basic division of radio waves and with parts, which are important for a high-quality receiver, then it deals with general properties of input networks of receivers, division of parts and kinds of connection, that are used in the communications. The concept of connection is intended to nonspecialists too, that is why it describes step by step each of parts of the network, including the calculation or possible solution and the choice of convenient parts. The aim is also to present the frequency conversion as an important part of signal receiving that we want to use in communication systems.
|
|
|
Line protection against overload and short circuit
Konšel, Ladislav ; Vaněk, Jaromír (referee) ; Valenta, Jiří (advisor)
This work includes a theoretical treatise on the operation of electrical wiring for the overload and short circuit. This is mainly on thermal effects of over current and their influence on the properties of conductors and insulation. Work Includes links to determine the load current, depending on the properties of leadership and its surroundings. It also deals with the protection of conductors against overload and short circuit. The work includes measurements process of warming wires. Practical project of proposal circuit is created using SICHR. The project includes proposals of conductor’s sizes and safety components for both residential building and individual flats.
|
|
|
MV Overhead Line Protections and their Coordination with Autoreclosers
Šoustal, Petr ; Skala, Petr (referee) ; Orságová, Jaroslava (advisor)
The aim of this Master’s Thesis is to describe protections for overhead lines in distribution networks. Here are described requirements for the protection and the basic protections. Protections are divided according to their protective function. For each protection is given its use and its power plans. It is stated in the work setting of protection in the real network. On this network is simulated place with short-circuit and described the action of protection. The work also deals with the coordination of protection with automatic circuit breakers. This chapter shows that, given the selectivity is not possible to deploy two or more reclosers (remotely-operated switches) to the core network management. The next chapter describes two representatives reclosers available on the Czech market OSM 27 and GVR 27. Chapter describes and compares their performance characteristics. Conclusion the work includes a proposal protected the lead in incorporating automatic circuit breakers (remotely operated circuit breakers and reclosers). The proposal is based on two different levels of annual number of interruptions and duration of annual general interruption of electricity supply. For these levels the company EGÚ Brno, a.s. proposed several variants of the use of remote-controlled in terms of reducing the cost of the penalty. Our task was to choose a variant that would be applicable in the real network. Reducing costs is feasible only in the limits Ln = 6 failures / year and Lt = 720 min / year, where the selected option No. 4. The limits Ln = 8 failures / year and Lt = 1,080 min / year, not in the real network may no option in terms of selectivity.
|
|
|
Laboratory device involving the high selectivity filters
Tuhý, Luboš ; Kovář, Jan (referee) ; Petržela, Jiří (advisor)
This project deals with the frequency filters of high selectivity. The area frequency filtering is fairly comprehensive and theoretically demanding discipline. The aim of this work isn’t to describe in detail and to include knowledge of the frequency filters, but only to clarify the aforementioned issues. In particular, we focus practically on filters working on other physical principles, especially on the crystal structure of partition filters and ceramic filters. The circuit simulation programs through classes Spice will be one of the parts of the theoretical analysis. There will be presented various options for implementing these filters, and the test products used in the design. The laboratory exercises dealing with frequency filtering and measuring engineered product will be made and based on the theoretical findings of this work. The laboratory exercises will include the developing of the model protocol.
|
|
|
A Low Voltage Wiring System for an Office Block
Nestrojil, Martin ; Slavata, Petr (referee) ; Kadlec, Radim (advisor)
This paper describes the design of a low voltage network in an office building. In the beginning work is given for the theoretical part of the topics that we need to create a network design in a given building. In this part of the guiding principles are conductor sizing, fuse wires and a selection of protective devices. Everything was sought in scientific publications and Articles. The theoretical part will be followed by a practical part with the first adjusted underlying schema, and then will address a practical design using programs supplied by the company Eaton. The goal of this work is to get acquainted theoretically with the main principles of network design, and then practically with your programs and create a complete network design of the building.
|
|
|
Photobiont plurality in lichen thalli
Dědková, Kamila ; Steinová, Jana (advisor) ; Vančurová, Lucie (referee)
Photobiont plurality refers to the presence of multiple photobionts within a single lichen thallus. This phenomenon was described at the end of the last century but has received deeper attention in the last decade. The available literature on this topic is limited. This bachelor thesis summarizes all the important findings published on plurality to date. The most common photobionts coexisting in a thallus are algae of the genus Trebouxia, but other algae and cyanobacteria more or less phylogenetically related may also coexist together. Thallus with multiple photobionts is formed either at the beginning by the association of hyphae with several photobionts at once (horizontal transport) or by the acquisition of additional photobionts during life (vertical transport). The most important factors affecting the cooccurrence of multiple photobionts in a single thallus are probably the specificity and selectivity of mycobionts and local environmental conditions. The plurality of photobionts has been found in more than fifty lichen species. Many important findings have been described in a model lichen Ramalina farinacea. Its coexisting photobionts differ in responses to several environmental, mostly stress conditions, suggesting that the presence of multiple photobionts in a thallus may provide an...
|
|
|
Influence of bases on heterogeneous Lewis acid catalyzed hydrogen transfer reactions
Veselá, Klára ; Přech, Jan (advisor) ; Bulánek, Roman (referee)
Heterogeneous Lewis acid zeolites catalyzed Meerwein-Ponndorf-Verley (MPV) reduction (transfer hydrogenation), where ketones and aldehydes are reduced to the corresponding alcohols. The hydrogen is taken from a secondary alcohol. These Lewis acid zeolite catalysts have a great advantage over homogenous catalysts as they are well separable from the reaction mixture and recyclable. Lewis acid zeolites are materials that contain incorporated tin or zirconium species, which act as Lewis acid sites. MPV reduction of citronellal provides citronellol as a product. However, the reaction of citronellal with 2- propanol also proceeds via a parallel reaction pathway providing isopulegol as the major product. Addition of pyridine (an organic base) to the reaction mixture switches the selectivity of the reaction, i.e., citronellol becomes the main product of the cited citronellal reaction with 2-propanol. It was investigated whether this phenomenon would also be observed for reactions with the addition of different bases. To answer these questions, Sn-BEA and Zr-BEA were prepared by hydrothermal synthesis. Impreg-Zr-BEA and impreg-Sn-BEA were prepared by postsynthesis metal incorporation. In addition, highly porous 2D Self-pillared pentasil zeolites containing tin and zirconium were hydrothermally synthesized....
|
|
|
Let's meet in the littoral: Diversity of symbiosis in the Verrucariaceae lichens
Schmidtová, Jana ; Škaloud, Pavel (advisor) ; Peksa, Ondřej (referee)
Lichens are organisms formed by several symbiotic partners, most importantly a fungus (mycobiont) and an alga or cyanobacteria (photobiont). Although most lichens are terrestrial, some can be found also in aquatic environments. Black crustose lichens from the family Verrucariaceae (Verrucariales, Eurotiomycetes, Ascomycota) were able to adapt to this environment very well and often dominate in the seashore near fluctuating water level. The ability of these lichens to inhabit various environments is associated with their unusually wide range of photobionts. However, this symbiont is not known to most of them. This work investigates the diversity of lichens of the family Verrucariaceae in the littoral zone of the Baltic and the North Sea coasts, the relationships between symbionts and the connection between lichen diversity and the salinity gradient. Using metabarcoding, the diversity of free-living algae in the vicinity of the studied lichens is determined and the symbiotic algae are compared with the photobionts found in the lichens. Mycobionts and photobionts were identified using ITS and 18S rDNA. A total of nine lineages of mycobionts and photobionts were found. The most common lichen turned out to be the species Hydropunctaria maura with its photobiont Pseudendoclonium submarinum. For several...
|
|
|
The efect of environmental variables on diversity of lichen photobionts
Červenková, Tereza ; Škaloud, Pavel (advisor) ; Peksa, Ondřej (referee)
Lichens represent a synergistic combination of at least two organisms, a heterotrophic fungus and a photosynthetic alga or a cyanobacterium. This association has resulted in a symbiotic organism, which is well tolerant to environmental influences. In fact, symbiotic relationship provides mutual benefit for both organisms. It is generally well known that the fungal partners of lichens are far less sensitive to environmental conditions, such as the temperature, altitude, rainfall or the type and composition of the substrate, in comparison to their algal partners. Therefore, lichen forming fungi have much wider ecological valences than the photobionts interacting with them. Indeed, most of the photosyntetic genera and species are adapted only to certain environmental conditions. For this reason, the symbiotic algae and cyanobacteria probably play a major role during the initial lichen formation on the site. This thesis focuses on the adaptability of photoautotrophic symbionts of lichens, coccoid green algae and cyanobacteria, to environmental conditions. Ecological diversification of photobionts has a direct impact on their genetic differentiation and thus to differentiate lichen species themselves. Unfortunately, in many studies the authors mostly dealt with the diversity of macroscopic symbiotic...
|
|
|
The organization of primary and lower secondary education in Europe: Comparative analysis of the Czech Republic and Finland in terms of equity.
Paulová, Kristýna ; Kalous, Jaroslav (advisor) ; Mouralová, Magdalena (referee)
This thesis is a comparative study, which compare two selected countries, Finland and the Czech Republic in the organization of basic education. The benchmark of equity has been chosen as a comparative criterion. This criterion was further divided into single indicators. The key indicator in this respect was the selectivity of educational systems. For this reason, the thesis presents especially the form and the extent of differentiation of students by each level of basic education in both chosen counties and try to find the number of children who are educated in them. The results of comparative analysis showed that five educational programs with different degree of quality exist in the Czech Republic, while there are only two types of schools in Finland. Finland has used the differentiation of pupils in schools, even in clases in much smaller scale in comparison with the Czech Republic. In Finland, there are no classes with extended teaching of some subjects. The next difference between selected countries is about the age when the students start to be selectived. The students are not differentionated before 16-years in Finland. On the other hand, students of the Czech Republic are divaded in various educational programs after completion of primary school, that means in 11-years. Only 4 % of...
|
guest ::
