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Cyclic Helicoid
Přikrylová, Ivana ; Chvalinová, Ludmila (referee) ; Borecká, Květoslava (advisor)
Cyclic helicoids belong to the descriptive geometry. The aim of this work is to demonstrate the cyclic helicoids and their use in engineering practice. First of all we will deal with the movement of screw, helix and its tangents. Then we will describe the general area, and cyclic helicoids. Cyclic helicoids split the position of the surface forming a circle relative to the axis of screw motion. Images complement the all important processes and geometric data. Images are drawn by the program Rhinoceros. Finally, we evaluate the use of cyclic helicoids in various fields and in everyday life.
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Assessment of Company Financial Situation Using Time Series
Dvořák, Václav ; Štěpánková, Vladěna (referee) ; Novotná, Veronika (advisor)
This bachelor’s thesis focuses on the use of statistical methods in practice, especially interested in the financial analysis of HELIX Liberec s.r.o. expressed by selected economic indicators in the time series from 2000 to 2010. The work has both theoretical and practical parts. The theoretical part is important to clarify the terms of the statistical and financial analysis in the practical part will apply the theoretical basis for undertaking an assessment of the situation and outline possible recommendations for improvement.
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Electrically short multiband antenna for radioamateur use
Müller, Marek ; Šebesta, Jan (referee) ; Lukeš, Zbyněk (advisor)
The purpose of this work is identification with theory of EH antennas, do the simulation of one choice of model of EH antenna from literature and this model optimise on required frequency 14 MHz through the use of computer software CST Microwave Studio. The practical part of work is to produce choice model of EH antenna, to mete his properties and to verify use in real traffic. The EH antenna is an electromagnetic electrically short antenna, which can work as a transmitting or receiving antenna. The main characteristic of EH antenna is distributed radiating electromagnetic field, whose electric component E and magnetic component H are mutually crossed and orthogonal. The advantage of EH antennas is, that they have much smaller size on frequencies in order of magnitude MHz in comparison with conventional antennas (e.g. half-wave dipole). Their disavantages are their more complicated construction and tuning of the antenna, which must be made again, when the position of antenna is changed. Therefore the EH antenna is not so suitable for mobile application.
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Multimodal Databases
Kuncl, Jiří ; Burget, Radek (referee) ; Chmelař, Petr (advisor)
This masters thesis is dedicated to theme of multimodal databases, especially multimedia databases. The first part contains overview of today's most used data models. Next part summarizes information about content-based search in multimedia content and indexing this type of data. Final part is dedicated to implementation system for storing and managing of multimedia content based on Helix streaming system a PostgreSQL database system.
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Worm conveyor
Sencovici, Patrik ; Jonák, Martin (referee) ; Malášek, Jiří (advisor)
This bachelor thesis deals with calculation and construction of worm conveyor for the transport of hydrated lime. Thesis is created from text part and drawing documentation. Text part be occupied with calculation basic parameters, design drive, loading, imposition of bearings and strength calculation of worm conveyor. Drawing documentation contains drawing assembly of worm conveyor and manufacturing drawings of spiral worm.
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Worm conveyor
Sedláček, Martin ; Jonák, Martin (referee) ; Malášek, Jiří (advisor)
This bachelor thesis deals with calculation and construction of worm conveyor for slightly sloping transport. The whole work is divided into two main sections, which include structural and textual parts. The text contains analysis of option for single parts of conveyor, functional and strength calculations, which are necessary for proposal of worm conveyor. The structural part includes mechanical drawings, which consists of drawing of configuration and drawings of details for worm shaft.
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Tuner for UHF Receiver with Low Power Consuption
Kaštánek, Martin ; Vágner, Petr (referee) ; Urbanec, Tomáš (advisor)
The purpose of this work was to make a proposal for input parts of receiver for band 430 to 440 MHz. A model of chosen semiconductor triode BFP540 was created in simulation software. Possibilities how to decrease consumption of this semiconductor triode, keeping the profit, were investigated through the simulation.In compromise consumption, keeping the profit of the amplifier - an optimal operating point for this semiconductor triode UCE = 1,2 V and IC = 2 mA was found. It was tested through the testing wiring with noise microstrips conformity. Ascertained knowledge was used for construction of tuner for UHF receiver. An operating point of input amplifier of UHF receiver was owing to power supply amplifier forced for bigger effectiveness to UCE = 2,65 V and IC = 2,0 mA. Suppression of mirror frequency is provided with Helix filter of the third order, because of intermediate frequency 10,7 MHz. Mixing on intermediate frequency is made again by semiconductor triode BFP540. Selectivity of receiver is provided with intermediate frequency crystal filter 10,7 MHz with bandwidth 15 kHz. Designed input part enables reception of SSB, FM and digital types of modulation.Bandwidth intermediate frequency exit is adapted to this request To receive particular modulation , it is necessary to complete intermediate frequency signal way with appropriate intermediate frequency filter.
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Antenna system for wireless microphones
Bartoš, Adam ; Lukeš, Zbyněk (referee) ; Láčík, Jaroslav (advisor)
Master's thesis deals with the design of an antenna system for wireless sound transmission used mainly in professional sound reinforcement. The introductory part deals generally with wireless microphones, frequency bands used and proven antenna types. Next, this work deals with signal distribution that is realized using the antenna splitter. The antenna parts is focused on easy production and real usage, therefore were selected antennas with appropriate properties suitable for small series production. This thesis includes simulation of each device, their real construction design and measurements of built prototypes and final products. All three produced devices – the rack splitter, /4 antenna and Helix antenna are fully working, achieve good parameters and are ready for further manufacturing and easy modifications in case of frequency band change requirement. The conclusion includes an overall assessment of the results achieved.
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Machining technology of external threads
Kabrda, Martin ; Osička, Karel (referee) ; Prokop, Jaroslav (advisor)
This bachelor's thesis focused on "Thread cutting technology" complexly deals with the individual types of threads, their designation and their use in practice, including norms specifying their standardization. There are also described methods of machining of external threads, which include cutting, turning, milling or grinding. The last chapter describes methods of economic comparison of individual machining methods.
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