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VoIP Security
Černý, Michal ; Číka, Petr (referee) ; Kovář, Petr (advisor)
Internet telephony becomes still more popular option to common telephone service. Reason may be it's price as well as availability. With growing popularity grows the risk of unauthorized use of transferred data too. There are several ways to secure VoIP communication. This bachelor's thesis talk about one of many, which is use of Secure RTP. There will be made it's implementation in the software telephone exchange Asterisk and tested functionality by trial talks and analysis of network traffic as well.
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Evaluation of the Financial Situation of a Company and Proposals for its Improvement
Vénos, Zdeněk ; Černý, Martin (referee) ; Bartoš, Vojtěch (advisor)
The main goal of this bachelor´s thesis is to research and evaluate the financial situation of the researched company from 2010 to 2014 with the help of the financial analysis, as well as suggest solutions leading to its improvement. In the first part of the thesis, there are stated facts and all necessary information used for better understanding of the exploring company with theoretical knowledge and methods used in the financial analysis. The next part contains actual analysis equipped with commentary.
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Half-mode substrate integrated waveguide horn antenna
Černý, Matěj ; Mikulášek, Tomáš (referee) ; Láčík, Jaroslav (advisor)
This thesis is about technology of half-mode substrate integrated waveguide (HMSIW) and options proposal of horn antenna fouden on this technology. Based on gained findings HMSIW horn antenna was modeled in program CST Microwave Studio. Main attention is focused on impact geometrical parameters of antenna on it´s emitting and on reflecting ratio at the entrance of antenna. Achieved gain of main lobe was 6 dBi, which is misalignmented to required direction of angle 30°. Antenna has a working frequency 10 GHz.
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First-principles study of stability of solid crystals
Pleskot, Ondřej ; Šesták, Petr (referee) ; Černý, Miroslav (advisor)
This work deals with a modeling of an electronic structure of solid crystals. Specifically, densities of valence electrons, and the density of states are calculated using first-principles code VASP for three crystals representing three different types of bonding. These are the metal bonding in a crystal of aluminum, the covalent bonding in a diamond crystal, and an ionic bonding in the crystal of rock salt. From calculated values of stress and crystal energy are then determined some macroscopic parameters of crystals, such as the equilibrium lattice parameter, the bulk modulus and the theoretical strength under isotropic tension.
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Vinyl prepolymers - methods of preparation and application
Černý, Miroslav ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
The theoretical part of this thesis is focused on bulk radical polymerization of styrene, methylmethacrylate, vinyltoluene and paramethylstyrene. It summarizes actual informations about kinetics and performance possibilities of bulk polymerization. Experimental part deals with polystyrene prepolymers preparation by bulk polymerization. The aim is to find optimal conditions for prepolymers preparation. Prepolymers should be usable for subsequent polymerization nearly up to 100% conversion. Conversion values were gravimetrically determined and molecular weights were obtained by viskosity measurements, which were realized by Ubbelohde viscometer. In the experimental part, there were performed simulations targeted on conversion dependence on time. The purpose was a prediction of monomer conversion at a given time during polymerization. Differences between reality and simulation were low in most of cases and the found form of kinetic behavior calculations provides satisfying results. In the conclusion of this thesis was suggested a new procedure for polystyrene prepolymers preparation.
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Animation in 3D Studio
Černý, Miloš ; Žák, Pavel (referee) ; Přibyl, Jaroslav (advisor)
The goal of this project is to inform readers about options of character animation. In theoretical part we discuss key-frame animation, forward and inverse kinematics and also the ragdoll technique. The aim of this work is to create a complex animation using 3D Studio Max with some of previously mentioned techniques.
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Stability of crystalline solids from first principles
Řehák, Petr ; Šob, Mojmír (referee) ; Černý, Miroslav (advisor)
This work deals with study of stability of solid crystals under isotropic loading. Ab initio methods were used for this purpose. Crystals of four fcc metals (Al, Cu, Ir, Au) and diamond were subjected to simulated isotropic tensile deformation and maximum value of isotropic stress was evaluated for them. Consequently, phonon spectra were calculated for several strain values in order to assess crystal stability. Phonon instabilities in dispersion curves of diamond, Al, Ir and Au appeared at strains lower than those corresponding to their decohesion. This appearance of instability determinates the value of ideal strength. However, significant reduction (by about 20%) was found only in the cases of Au and Ir.
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