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Fractal capacitors properties
Chvíla, Ladislav ; Sedlák, Petr (referee) ; Hruška, Pavel (advisor)
This work is focused on computer simulations of fractal capacitors. The geometry of capacitors and its influence is investigated. Simulations are realized in programs Matlab, SolidWorks and Comsol Multiphysics. There are also several specific examples of different geometrics of capacitors their comparisons and assessment.
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Model of tissue heating by KV diathermy
Bažantová, Lucie ; Čížek, Martin (referee) ; Rozman, Jiří (advisor)
This thesis deals with the basic theory of the electromagnetic field in the first part and the field interactions with biological tissues. Than describes shortwave diathermy as a technique used for purposes of medical treatment. The aim is to built a model of tissue heating in shortwave diathermy in COMSOL Multiphysics environment, so there is included a description of the programming environment, including the mathematical method that COMSOL uses for calculations. The output of the whole work is a model of the lower limb in the knee part and display the results after his diathermy heating.
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Computer modeling of laser beam
Mittner, Ondřej ; Wilfert, Otakar (referee) ; Raida, Zbyněk (advisor)
This bachelor’s thesis theoretically describes Gaussian beam, its characteristics and its passing through optical elements. The main attention is focused on creating of computer models of Gaussian beam in COMSOL Multiphysics application, detailed description of these models, presentation of achieved results and comparing these results with theoretic presumptions.
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Modeling non-conventional monopoles in COMSOL Multiphysics
Zmeškal, Vladimír ; Olivová, Jana (referee) ; Raida, Zbyněk (advisor)
The project deals with the computer simulation of non-conventional monopoles in the program COMSOL Multiphysics. First, the methodology for using COMSOL Multiphysics is described. Second, we concentrate on the design and modeling of three types of non-conventional monopoles: the conical one, the capacitively loaded one, and the drop-shaped one. For each monopole, directivity patterns are displayed. The influence of the variation of antenna dimensions to its parameters is discussed. Monopoles are mutually compared. Finally, models of monopoles are completed by global optimizations techniques: genetic algorithms and particle swarm optimization. That way, a design tool is developed in MATLAB.
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Computer modeling of MOSFET transistor
Major, Jan ; Harwot, Ondřej (referee) ; Pokorný, Michal (advisor)
Work is focused on computer modeling of PN junction and MOSFET transistor in the program COMSOL Multiphysics and in program TiberCAD. The text is discussed on the drift and diffusion in semiconductors. Also shown is a method of modeling the PN junction and MOSFET transistor in the programs and compare models.
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Numerical method for computing electromagnetic field
Bíreš, Pavol ; Čížek, Martin (referee) ; Rozman, Jiří (advisor)
The aim of the work is to study the electromagnetic field theory, finite element method and the interaction of electromagnetic field with tissues. Gained knowledge is then used to calculate spreading of the electromagnetic field in the microwave field and to create a temperature profile of spreading the electromagnetic fields in human tissue. The finite element method was implemented in the Matlab programming environment, where the 1D model was created in the frequency and time domain and a simple 2D model created in time domain. The program was developed to analyze spreading electromagnetic wave. Another part of work was done in the programming environment of COMSOL Multiphysics. In this case was the human leg exposed to electromagnetic fields. The analysis determined the changes of temperature in these biological tissues for six minutes.
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Multiband magnetic antenna
Ryšánek, Martin ; Hertl, Ivo (referee) ; Raida, Zbyněk (advisor)
The thesis deals with a parametric analysis of a magnetic multiband antenna and explains the principle of its operation. In the thesis, an optimization of the antenna by the particle swarm optimization is performed in order to meet impedance matching in prescribed frequency bands.
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Synthesis of electromagnetic bandgap structures
Šedý, Michal ; Kovács, Peter (referee) ; Raida, Zbyněk (advisor)
In microwave frequency band, the planar technology is mainly used to fabricate electronic circuits. Propagation of surface waves belongs to the significant problem of this technology. Surface waves can cause unwanted coupling among particular parts of the structure and can degrade its parameters. The problem can be solved using an electromagnetic band gap structure (EBG). These periodic structures are able to suppress surface waves in different frequency bands. This thesis is focused on the modeling of these structures in the program COMSOL Multiphysics.
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Modeling waveguides by time-domain finite elements
Fasora, Pavel ; Motl,, Milan (referee) ; Raida, Zbyněk (advisor)
The thesis deals with frequency domain finite elements and time domain finite elements. Derivation of the wave equation, generation of the discretization mesh and the composition of matrices for solving wave equation are presented. Exploitation of COMSOL Multiphysics for the analysis of the electromagnetic wave propagation in a wave guide is explained. Finally, in this thesis is described the m-file of MATLAB for analyzing electric field intensity of the waveguide in longitudinal direction to both domain. In last part is concisely exposed perfect match layers.
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Modeling frequency selective surfaces in COMSOL Multiphysics
Höhn, Tomáš ; Oliva, Lukáš (referee) ; Raida, Zbyněk (advisor)
Metoda konečných prvků implementovaná v programu COMSOL Multiphysics je využívána k analýze tzv. free-standing kmitočtově selektivních povrchů ve 3D. Tyto modely jsou následně doplněny o periodické okrajové podmínky. Dále jsou free-standing povrchy doplněny o vrstvy dielektrika a je zkoumán jejich vliv na modul činitele odrazu. V analytické části jsou vyhodnoceny vlivy počtu elementů diskretizační mřížky na přesnost výsledku a délku výpočtů. Výsledky jsou srovnávány vzhledem k výsledkům uvedeným v literatuře [5]. V závěrečné části práce je vysvětlen postup při generování m-file pro obdélníkový element a použití globálního optimalizačního algoritmu PSO, který automaticky upravuje rozměry vodivého motivu tak, aby bylo dosaženo průběhu modulu činitele odrazu podle požadovaného průběhu.
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