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Reconfigurable slot antenna array
Weigel, Filip ; Pítra, Kamil (referee) ; Raida, Zbyněk (advisor)
This master's thesis deals with the basic principles of slot antennas. Models of antennas were simulated in a selected electromagnetic simulator CST MICROWAVE STUDIO (CST MWS). There are several models of slot antennas which are optimized for communication in the car at a frequency 8 GHz.
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Measurement of insulation and dielectric properties of water.
Žvátora, Jaroslav ; Starý, Jiří (referee) ; Špinka, Jiří (advisor)
This bachelor thesis deals about dielectric and insulation properties of water. It describes the structure of water, hydrogen bonds. It explains primary physical and chemical properties of water and then it describes parameters of water such as dynamic viscosity, conductivity, surface pension, loss factor, polarization. Part of the work is practical section, which deals measurements of water and shows primary dependence such as capacity dependence on frequency or loss factor on frequency.
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Measurement of the piezoelectric charge coefficient
Stehno, David ; Uher, Miroslav (referee) ; Fialka, Jiří (advisor)
The thesis aim was to study in theory the determination of piezoelectric coefficients, in particular piezoelectric coefficient of charge and to use different measurement methods to determine this factor. Also to further study the issue of determining the uncertainties and determine the measurement uncertainty. Measurements were conducted on cylinder-shaped samples, with different dimensions of individual samples. With type material PCM51 and PCM41. Piezoelectric coefficient measurements of charge was carried out using three methods: frequency, direct and quasi-static. The results achieved by all methods are compared at the end of this study and the measurements uncertainty are calculated and discussed for each method.
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Electrical properties of modified oligobutadienes
Toulová, Jana ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
Bachelor thesis deals with the behavior of dielectric materials in an alternating electric field. To identify the properties of dielectric materials in the frequency domain method was employed dielectric relaxation spectroscopy. On several samples of modified oligobutadiénů were measured frequency dependent components of the complex permittivity in the temperature range of negative temperatures, the ambient temperature.
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Quality of Services in Optical Access Networks
Šifta, Radim ; Křepelka, Václav (referee) ; Vlček, Čestmír (referee) ; Filka, Miloslav (advisor)
The thesis focuses on the optical access networks and deals with the issue of transmission parameters of the physical layer, their negative impact on the quality of the services parameters and the possibilities of reducing their effect using the polarization multiplexing. The first and second chapter describe the theoretical background necessary for understanding the subsequent parts. The third chapter contains the practical part of the thesis. At first the optical routes in the Czech Republic in terms of polarization mode dispersion, which is together with insertion loss the main limiting parameter of high-speed optical networks, are evaluated. In the following part the measuring of the temperature changes effects on the polarization mode dispersion of the passive components and the effect of temperature changes to the polarization multiplexed signal are evaluated. To double the bandwidth and reduce the influence of polarization mode dispersion on the quality of services, the two simulation models of optical access networks using polarization multiplexing were carried out. These theoretical outputs were verified by the practical measurements in the laboratory and subsequently on the real optical route. Finally, a draft of the broadband optical access network based on wavelength and polarization multiplexing was designed based on obtained knowledge.
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Analysis of an Electromagnetic Wave on the Boundary between Electromagnetic Materials
Kadlec, Radim ; Lazar, Josef (referee) ; Macháč, Jan (referee) ; Kroutilová, Eva (advisor)
The proposed dissertation thesis contains an analysis of conditions on the boundary between layers having varied electromagnetic properties. The research is performed using consistent theoretical derivation of analytical formulas, and the underlying problem is considered also in view of multiple boundaries including the effect of the propagation of electromagnetic waves having different instantaneous speed. The author presents a survey and formulation of the basic characteristics of methods used for electromagnetic wave propagation analysis; in this respect, special emphasis is placed on radial models. The processing of the topic involved the designing and verification (using a set of different, layered planar materials) of algorithms to analyze the electromagnetic field components. The algorithm was assembled to enable simple evaluation of all components of the electromagnetic field in relation to the speed of the wave propagation in a heterogeneous environment. The proposed algorithms are compared by means of different numerical methods for the modelling of electromagnetic waves on the boundary between materials; moreover, electromagnetic field components in common points of the model were also subject to comparison. When in conjunction with tools facilitating the analysis of material response to the source of a continuous signal, the algorithms constitute a supplementary instrument for the design of a layered material. Such design enables the realization of, for example, recoilless plane, recoilless transition between different types of environment, and filters for both optical and radio frequencies.
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Study of Scattering and Polarization of Light in Biological Tissue
Abubaker, Hamed Mohamed ; Hrabovský, Miroslav (referee) ; Číp, Ondřej (referee) ; Tománek, Pavel (advisor)
Tkáňová optika nabývá rychle na významu a přesná znalost optických vlastností biologických tkání je podstatná pro výzkum v biomedicíně i pro kontrolu kvality potravin. Jestliže je vzorek tkáně osvětlen, dochází k mnohonásobnému odrazu světla. V případě postmortem neživých tkání (maso) je rozměr buněk větší než vlnová délka použitého světla. Dochází k Mieovu rozptylu prošlého nebo zpět odraženého světla, v důsledku čehož se objevují různé polarizační stavy světla. Polarizační stavy světla rozptýleného na difúzním prostředí jsou experimentálně zkoumány a modelovány. V práci jsme provedli dva modifikované experimenty: rozptyl polarizovaného světla, které dvakrát prochází vzorkem (vpřed a vzad) a jen světla, které jen prochází vzorkem. Měření rozptýleného světla ukazuje, že dochází k depolarizaci a ke stáčení polarizační roviny, což obojí závisí na orientaci svalových vláken a stárnutí tkání postmortem. Mimo experimentů byl také proveden teoretický popis difúzní biologické tkáně a byla vypočtena radiační přenosová rovnice pomocí modifikované Monte Carlo metody, která zahrnuje polarizační stav světla (PLMC). Je ukázáno, že stupeň polarizace podstatně závisí na optických vlastnostech rozptylového prostředí. Výsledky ukazují, že stav polarizace světla na výstupu závisí na stavu polarizace světla před vzorkem a na optických vlastnostech a tloušťce vrstvy prostředí v průběhu jejího stárnutí. Je také provedena korelace změn polarizace na čerstvosti masa, i popis dynamického chování polarizace při stárnutí masa.
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Behaviour of ferroelectrics in an electric field
Krejčí, Josef ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
The submitted thesis describes characteristics and use of ferroelectric materials which find their utilization in electrotechnical and electronics industry. The thesis is mainly aimed at their behaviour in the electrical field at various intensity and also focuses on their diagnostic methods. The method using an oscilloscope is selected as the most suitable and described here in more detail. Measuring laboratory workplace for detection of characteristics of ferroelectric materials in the electrical field has been innovated with available equipment and then its utility has been verified. Temperature and electric tension dependence of components of complex permittivity and electric condition of the material has been scaled using selected samples of ferroelectrics. A text in an electronic form has been integral part of the thesis. The text can be used as an instruction manual for laboratory trainings.
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Optoelectronic sensor of polarization state of transmitted light
Bajgar, Aleš ; Rampl, Ivan (referee) ; Tománek, Pavel (advisor)
The living body tissues consist of cells which dimensions are bigger than a wavelength of visible light. Therefore a Mie scattering of transmitted light occurs and different polarization states arise. The changes of polarization state due to the multiple scattering of light in the biological cellular tissues allow measure the aging of biological tissue. The transmitted polarized laser light exhibits multiple scattering on the thin slice of sample.
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3D data presentation
Bastl, Petr ; Petyovský, Petr (referee) ; Richter, Miloslav (advisor)
This bachelor thesis informs about methods for 3D perception. Basic principles of autostereoscopic methods like SIRDS, anaglyph and projection stereo images by two projectors and anaglyphic or polarizing filters are described here. The procedure for generating the view on 3D by means of so-called depth-image-based rendering (DIBR) techniques is analyzed as well. An overview of technologies and formats for projection and simulcast spatial image is stated in this thesis too.
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