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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Hloubkové profilování multivrstev metodou LEIS / Depth profiling of multilayers by LEIS

Strapko, Tomáš January 2019 (has links)
Diplomová práce se zabývá vytvořením modelu, který by umožnil lepší interpretaci hloubkových profilů měřených metodou LEIS. Obtížnost interpretace těchto profilů je dána vysokým podílem vícenásobně odražených projektilů v meřených spektrech. Tyto projektily nepřináší užitečnou informaci z dané hloubky. Naproti tomu jednonásobně odražené projektily nesou přesnější informaci o složení a tloušťce vrstev. V této práci vytvořený model se snaží určit příspěvek jednonásobně odražených částic k celkovému tvaru spektra a na základě něj i hloubkový profil vzorku.
2

Polarizační verze lesklých BRDF modelů / Polarising Versions of Glossy BRDF Models

Bártová, Kristina January 2014 (has links)
The goal of computer graphics is to precisely model the appearance of real objects. It includes of interactions of light with various materials. Polarisation is one of the fundamental properties of light. Incorporating polarisation parameter into an illumination model can significantly enhance the physical realism of rendered images in the case of scenes including multiple light bounces via specular surfaces, etc. However, recent rendering systems do not take polarisation into account because of complexity of such a solution. The key component for obtaining physically correct images are realistic, polarisation capable BRDF (Bidirectional Reflectance Distribution Function) models. Within this thesis, polarising versions of the following BRDF models were theoretically derived: Torrance Sparrow, He-Torrance-Sillion-Greenberg and Weidlich-Wilkie. For each of these models, Mueller matrices (the mathematical construct used to describe polarising surface reflectance) were systematically derived and their behaviour tested under various input parameters using Wolfram Mathematica. Derived polarising glossy BRDF models were further implemented using a rendering research system, ART (Advanced Rendering Toolkit). As far as we know, it is the very first usage of these BRDF models in a polarisation renderer....
3

Využití metamateriálů pro zlepšení parametrů antén / Improving antenna parameters by the application of metamaterials

Šporik, Vladimír January 2009 (has links)
The thesis is focused on the design of a planar resonant-type antenna, which exploits a proper combination of left- and right-handed properties of transmission lines. This transmission line is called CRLH TL and is based on Sievenpiper mushroom structure. Advantages of the proposed antenna concept are demonstrated by a detailed comparison of its basic properties with the properties of a conventional patch antenna.
4

Speciální metody mikrovlnných vektorových měření / Special Methods for Microwave Vector Measurements

Urbanec, Tomáš January 2008 (has links)
Theoretical principles of the sixport measurement method are presented. Description of theoretical design and influence of its parameters on measurement precision follows. Simple sixport measurement system was made and its parameters are described. As the main thesis contribution there is described a new approach to method with more detectors in the system. Mean features are more valid sixports at one specific frequency and frequency bandwidth aviable up to 1 : 100 and more. Such a wideband measurement system was designed for the frequencies between 50 and 2680 MHz and its parameters are presented in the work.
5

Širokopásmová vektorová měření / Wideband Vector Measurements

Dvořák, Radek January 2013 (has links)
Thesis describing design and measurement of the vector reflectometer system based on six port principle. The expectations for precision measurement in wide bandwidth system are explained. Diode linearization problem is described and the calibration method especially designed for the wide band systems is explained. And finally several data processing methods for the final result decision are compared.
6

Návrh antény s kruhovou polarizací pro kmitočtové pásmo 2,4 GHz / Design of circular polarized antenna for 2.4 GHz

Hase, Michal January 2008 (has links)
In this thesis, I introduce two types of circularly polarized rectangular microstrip antennas at 2.44 GHz. First type has direct fed and the second has two inputs for fed. In first case is used a stub to make the frequency with minimum return loss and equal to the frequency with minimum axial ratio. In second case is use the power splitter to divide the wave in to two lines with phase shift 90° for feeding the patch. In this thesis is described, how to get the best results of Axial Ratio.
7

Měřící metody klíčových parametrů v optických sítích / Measuring methods of key parameters in optical networks

Balon, Jiří January 2010 (has links)
The main goal of the master’s thesis was to familiarize with optical networks dilemma and its measuring during fabrication. The whole thesis is divided into several parts where the first part deals with optic fiber dilemma. It describes its kinds, properties and also suggests a basic principle of optic signal dispersion using these fibers. It describes also optical network FTTx architecture (Fiber To The x). The second part of the thesis focuses on methods of measuring key parameters of optical networks. Is brings out the methods of measuring optical loss and dispersive influences. The last and final part in focused on creating a methodical manual for measuring these networks during its fabrication and verifying measuring methods stated in the theoretical part inside a real network. Measuring was implemented on an optical network of Masaryk University in Brno.
8

Automatický anténní analyzátor / Automatic antenna analyser

Dufek, Ivo January 2010 (has links)
This project is dealing with methods of measuring impedances of the antenna systems in the frequency range from the low frequencies to the very high frequencies. There is a discussion about different methods of measuring impedance and each technique is critically evaluated. In terms of this project is compared few types of the professional antenna analyzers. According to this comparison there was made the concept of my own antenna analyzer. There is a detailed description of the design of this device’s important parts including software equipment. Designed instrument has been built and tested.
9

Simulace monitoringu optické trasy / Simulation of optical route monitoring

Mlejnek, Zbyněk January 2010 (has links)
Monitoring optical line for a long term monitoring and evaluating both transfer quality and running reliability of optical line links' physical layer (optical cable routes) fiber optical transfer systems. Monitoring indicates any kind of security erosion of transmission medium incited by either "natural" climatic and mechanical environmental effects, indeliberated cable violation (building operation) or by intended intervention into transfer path.
10

Strukturní a morfologická charakterizace polyamidových spon / Structural and morphological characterization of polyamide buckles

Kubíčková, Eva January 2016 (has links)
The work deals with structrural and morphological characterization of polyamide buckles used to fasten webbins. The buckles were produced in five different years, a few of those produced in 2000 and 2004 were broken. The aime is to determine the type of polyamide and the cause of fracture of the buckles during using. The buckles were characterized in terms of structure and composition by Fourier-transform infrared spectroscopy in a mode of attenuated total reflaction, differential scanning calorimetry, thermogravimetry and X-ray diffraction. The buckles were made of polyamide 12. The broken buckles showed higher melting point, lower thermal stability and, in addition to modification it also contains modification, which is more fragile and probably represents the cause of fracture.

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