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Solid stick friction modifiers for rail transport
Ondák, Andrej ; Hajžman, Michal (referee) ; Galas, Radovan (advisor)
The present work deals with solid friction modifiers, which are substances that have the task of reducing the contact friction of the wheels of railroad vehicles, thus reducing wear and noise emission. In order to maximise the efficiency of the system, material consumption must be kept to a minimum. When solid friction modifiers are applied, there is a danger of isolation of the contact, which is an undesirable effect regarding track systems. At the moment, both the positives and the negatives of the technology are known, but without a deeper connection to application parameters. Therefore, the experimental part of the thesis is focused on determining the influence of application on the performance of rigid friction modifiers. The thesis also focuses on the effect of the working frequency of the track systems on the contact impedance and on the consumption of the compositions themselves. As a result of the research, the application parameters strongly influence the performance of the solid compositions. It was also observed that the friction modifier tends to adhere to the surface of the body, to which it is applied and thus there is no transfer to the other body. On the contrary, it was found that the contact impedance is independent of the working frequency. The development part of the thesis is dedicated to the design of a solid composition applicator and a device for measuring the impedance and consumption.
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Study of DNA-doxorubicine interaction by electrochemical methods on nanostructured electrodes
Přibyl, Jakub ; Fohlerová, Zdenka (referee) ; Kynclová, Hana (advisor)
Cancer diseases are one of the leading causes of mortality worldwide, for this reason, great attention anticancer drugs. Doxorubicin falls into the category of the most widely used cancer drugs. The method of electrochemical impedance spectroscopy were investigated properties of golds electrodes without deposit nanoparticles and electrodes with deposit gold nanoparticles. Using voltammetric measurements we detected doxorubicin and investigated the interaction of doxorubicin with oligonucleotides on gold electrodes without nanoparticles and electrodes modified with gold nanoparticles.
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Design of optoelectronic sensor for biological tissues
Balík, Zdeněk ; Bartlová, Milada (referee) ; Tománek, Pavel (advisor)
Biological tissues are optically inhomogeneous and absorbent materials. They are comprised of various structures such as cells, cell organelles, and various fiber structures. Due to these structures leads to different interactions with the light and phenomena such as absorption, scattering and polarization of light. Different ultrasonic, electromagnetic, electrical and optical methods are used for meat ageing detection. Muscles are turbid anisotropic media, they exhibit changes in electrical and optical properties according to the direction of the electrical and optical fields in the sample. The diploma work assesses the feasibility of impedance measurements for meat ageing detection and their comparison with optical measurement of scattered polarized light. Two different sample were used: pork chop slices and chicken breasts were used for their relative homogeneity. The electrical method is a promising method due to the possibility of getting much information and realizing cheap and fast enough measurement systems. The proposed optical method allows measure the rotation of polarization plane with meat ageing in the range of 95 degrees within considered period. Through the first promising results obtained in this thesis, a further work has to be provided to determine closer relationship between optical scattering characteristics, electrical anisotropy in ageing-related tissue structural properties.
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Model for power line communication
Baluch, Viliam ; Fujdiak, Radek (referee) ; Mlýnek, Petr (advisor)
This bachelor thesis is dealing with matters of data communication after power line. The thesis is including the PLC systems history, current possibilities of utilization and different types of modulations being used, interference sources and parameters of a transmission line. We will elaborate on methods of transmission line modeling and one of them will be used in the practical part of the thesis. The practical part consists of modeling of different types of topology and impedance endings applying generation of random transmission parameters and sizes of typology. We analyze results from practical measurement which are incorporated in a model. The model is then being compared with another one in terms of fixed parameters.
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Measurement of tissue impedance during electroporation
Uher, Jakub ; Novotná, Veronika (referee) ; Červinka, Dalibor (advisor)
The Bachelor's thesis is devoted to the impedance of tissue in relation to the modern medical method electroporation. The Bachelor's thesis is divided into five chapters. The first three chapters describe the behaviour of the tissue and its impedance, whether during the passage of an electrical current or a phenomenon before and after the electroporation procedure. The fourth and fifth chapters examine those phenomena in the previous chapters on measurements made on animal and plant tissue.
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Power line channel simulator
Jedlička, Tomáš ; Fujdiak, Radek (referee) ; Mlýnek, Petr (advisor)
The master’s thesis is focused on the analysis and modeling of power line communication with aim to implement power line channel simulator in the programming environment Matlab. At the beginning of the thesis are summarized basic information about the PLC communication, its basic distribution in terms of frequency bands and are also mentioned advantages and disadvantages. The emphasis on the meaning and importance of modeling with the aim to analyze PLC communication channel is specified further. The following is a detailed description of the current power lines communication models. Power line channel simulator was created on the basis of mathematical analysis for low-voltage (LV) distribution networks. The created simulator uses a model of cascaded two-ports and works in random or fixed mode. Input parameters are real topologies, different types of loads and cables. RLC resonant circuit as a frequency selective impedance is also included in impedance models. Based on the obtained results was performed the analysis, determined the critical parameters and extreme values. Comparison of effectiveness of created simulator was processed on the basis of available simulators from other authors. Two versions of simulator were created using the results obtained under comparison of effectiveness. For comparison was also performed real measurement on a simple topology. The experimental measurements results have been implemented in the simulator.
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Design of measuring solutions for circuits with differential signals
Jemelík, Lukáš ; Hanák, Pavel (referee) ; Jeřábek, Jan (advisor)
This master´s thesis deals about a measuring structures of elements working at a current mode. There were outlined structures for measuring input and output impedance. These structures were simulated for DACA element. It deals with a voltage to current and current to voltage converters. All structures and converters were simulated at computer program PSpice. Selected variant were practically verified and control measuring was realized.
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Stabilized operation of the 400 kV power line
Jurča, Ondřej ; Bok, Jaromír (referee) ; Blažek, Vladimír (advisor)
This thesis deals with methods of solving lines under voltage levels of a very high transmission voltage and extra high voltage. The first, theoretical part of this paper analyses different methods how such lines are solved. In particular, an accurate solution is provided simulated by means of a line with evenly distributed parameters, and an approximate solution simulated by means of a line with lumped parameters. Furthermore, special cases of steady running conditions of the line are reviewed, such as no-load running, short-circuit run and line operation with natural load. In conclusion of the theoretical part is given a general method of solving an extra-high-tension and extra high voltage network; also, some graphical methods of solving such networks are shown including their brief description. The second, practical part of the present paper involves application of the above mentioned methods of solution on a specific line with given parameters, solving conditions at the beginning of the line under steady running conditions and in special cases of the line operation. The conclusion of the thesis summarises the obtained results and provides final assessment of the individual methods of solution in terms of calculation accuracy.
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Design and implementation of interconnection tools for noise generator
Pokorný, Jiří ; Kubánek, David (referee) ; Krajsa, Ondřej (advisor)
The bachelor’s thesis explores the way of implementation of interconnection of LFTX Daughterboard 0-30 MHz Tx and LFRX Daughterboard 0-30 MHz Rx cards from Ettus research and cards from Spectrum Digital. In the first part of the thesis the design of two tools for two way transmission is shown. The paper contains everything from the basic findings through parts selection nad simulations to the final production and testing of the tools. In the second part a way of controlling similar tool through USB is explored.
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Automatic Antenna Tuner
Šváb, Jaroslav ; Lukeš, Zbyněk (referee) ; Šebesta, Jiří (advisor)
This degree work deals with the design and implementation of an automatic antenna tuner for short-wave transmitters. The device works within the short-wave range in (1.5 MHz - 30 MHz) band according to the selection of the given frequency. Its principle is that the tuner has a small range of adapted impedances, but it is usually sufficient for fine tuning of most deviations in the system of antenna 50 - feeder 50 - transceiver outlet 50 . It is also equipped with memories which the settings for the individual bands or frequency segments are stored into. Then the transition from one band to another is quick, easy and, first of all, safe, which is a great advantage. In automatic mode, a SWR limit from which the tuner should start to tune can be set. Interconnection with a TRX is not necessary in a fully automatic mode, the device tunes automatically after keying if the set limit of SWR has been exceeded. The automatic tuning is very quick with this device, if the antenna being tuned is not stored in the memory the tuning lasts ca 0.5 - 6 s, if the tuner uses the memory. It could be said that the work with the tuner is without problems, it is possible to learn to control it in a short time. The tuner is small and light. The result of the whole project is a compact device controlled by the user by means of push buttons.
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