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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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Utilization of artificially created weak magnetic field for navigation in 3D space
Váňa, Dominik ; Beneš, Petr (referee) ; Havránek, Zdeněk (advisor)
This master's thesis focuses on the utilization of an artificially created weak magnetic field for navigation in 3D space. The theoretical part of this work deals with the general properties of the magnetic field and with its description. The next section of the theoretical part contains an overview of measuring principles for magnetic field measurements. Based on various types of measuring principles, the thesis elaborates on commercially available miniature sensors for magnetic field measurement with a measuring range up to 10 mT. The work focuses mainly on the magnetoresistive principle and fluxgate sensors. Furthermore, the theoretical part contains descriptions of methods for modeling the magnetic field of simple permanent magnets and various magnet assemblies. Lastly, the theoretical part involves a patent search of devices used for locating magnets that are installed in an intramedullary nail, which is used in intramedullary stabilization used on fractures of human bones. By locating the magnet in the nail, it is possible to precisely determine the position of the mounting holes. The practical part of the thesis deals with the analysis of magnetic field behavior in the vicinity of various magnetic assemblies, which were modeled in COMSOL Multiphysics using the finite element method. The models were created with the aim of analysing the behaviour of the magnetic field in the vicinity of the magnets and at the same time to find possible analytical functions that could be used to determine the position of the magnet in space relative to the probe. The result of this work is an analysis of various assemblies, which contains graphs of different dependencies and prescription of polynomial functions that approximate these dependencies. Another part of the thesis is the design of a probe that serves to locate the magnetic target. The work describes two possible methods of localization. For the differential method, a user interface in LabVIEW was created. The probe based on this method is fully capable of locating the magnet in the 2D plane. The state space search method is described only in theory.
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Modelling of bioelectronic devices
Truksa, Jan ; Vala, Martin (referee) ; Salyk, Ota (advisor)
Tématem této práce je počítačové modelování organického elektrochemického tranzistoru (OECT). Pro vytvoření modelu bylo třeba vypočítat rozložení elektrického pole a koncentrace iontů elektrolytu. Výpočet byl proveden numericky pomocí metody konečných prvků. Bylo vypočítáno rozložení elektrického potenciálu na povrchu kanálu OECT, dále byly vypočítány změny vodivosti a výstupní proud OECT. Výpočty byly provedeny na osobním počítači pomocí komerčního softwaru COMSOL Multiphysics. Kvůli nedostatečnému výpočetnímu výkonu musel být model rozdělen na části a drasticky zjednodušen. Prezentované výsledky se liší od literatury, protože se nepodařilo správně modelovat saturaci tranzistoru. Odchylky od reálného chování OECT jsou pravděpodobně způsobeny zjednodušením modelu.
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Magnetic drive
Aubrecht, Ondřej ; Pokorný, Michal (referee) ; Raida, Zbyněk (advisor)
In the bachelor thesis, selected types of magnetic motors are analyzed and mutually compared. For each motor, a short description is given and critical evaluation of its properties is provided. In the next part of the project, all the magnetic motors are mutually compared and a suitable type of the motor for the computer simulation is chosen. The simulations are performed in programs COMSOL Multiphysics and program Femm. In the last part of the project, simulations are checked on the real prototype of magnetic motor.
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Model of electric furnance for heat-resistant material processing
Franek, Lešek ; Malounek, Petr (referee) ; Dvořáček, Martin (advisor)
Content of the document is to create model of kiln, compare result with the real kiln. There is described 3D design in SolidWorks application, creation of a physical model in COMSOL Multiphysics and its export to Simulink. Subsequently is described the Simulink scheme, functions of program parts and visualization in B&R Automation Studio. The obtained results are compared with measured values. There is also described the design of a controller with a off-line identification.
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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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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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Computing directivity patterns in Comsol Multiphysics
Ryšánek, Martin ; Lukeš, Zbyněk (referee) ; Raida, Zbyněk (advisor)
The individual project – Computing directivity patterns in Comsol Multiphysics. In the first part, the theoretical background for monopole antennas is reviewed. The second part is focused on the analysis of several types of monopoles in COMSOL Multiphysics, and on the calculation of their radiation patterns and impedances. Finally, simulation results are presented and discussed.
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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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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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