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Mathematical modelling diffusion of metal ions in humic gel
Masár, Lukáš ; Ing. Eva Gregorová,CSc. (referee) ; Klučáková, Martina (advisor)
The subject of this bachelor thesis was simulation of diffusion processes proceeding in the reactive gelous media using the COMSOL Multiphysics software. The aim of this study was to develop a comprehensive set of models available for the interpretation of experimental data obtained in the study of metal ions transport in the humic acids hydrogel. The main consideration was given to the influence of porosity modelling and chemical interactions on the diffusion characteristics (mainly diffusion flow). Within the simulation of the influence of chemical reactions, different kinetic models were used (one-way reaction of first and second order and reverse reaction).
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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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Relative Displacement Sensor
Koutný, Petr ; Havránek, Zdeněk (referee) ; Beneš, Petr (advisor)
This thesis deals with design of optimal parameters of a relative displacement sensor, working on the electrodynamics principle. The sensor is based on the voltage induction to the coil placed in changing magnetic field. Thesis is divided into three parts: introductory, theoretical and practical. The introductory part provides basic relationships between displacement, velocity and acceleration sensors. The theoretical part contains physical concepts and describes relationships necessary for calculations and creating a model of permanent magnet in COMSOL Multiphysics. In thesis further presents patent research of electrodynamic sensors. The practical part describes the creation of the permanent magnet model and the subsequent calculation of the induced voltage in the coil in Matlab. A description of laboratory measurements follows, presenting the final comparison of the simulation and measurement results. There were found some differences, which might have been caused by incorrect calculation of the induced voltage. The final part of the thesis presents general recommendations for the design of sensor, resulting from simulations and measurements.
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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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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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Modeling and optimization of patch antennas
Šídlová, Ludmila ; Láčík, Jaroslav (referee) ; Raida, Zbyněk (advisor)
This work is engaged in modeling of patch antennas. It describes various types of synthesizing the layout and designing the microstrip feeder or probe feeding. This work is focusing on modeling and creating a patch antenna for 6 GHz fabricated from ARLON 25N and fed by a microstrip. The layout is first calculated from required antenna parameters and substrate parameters. The optimization of the patch antenna is carried out in the program ANSOFT Designer, which analyzes planar structures by the moment method. The fabricated patch antenna is measured by a vector analyzer. Results of measurements and computations are compared in terms of frequency response of the standing wave ratio for the frequency interval from 5.5 to 6.5 GHz. The patch antenna is also modeled in the program COMSOL Multiphysics as a two-dimensional conical monopole with a coaxial feeding, and a three-dimensional patch fed by a microstrip; the design is optimized for the operation frequency 6 GHz.
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COMSOL Multiphysics ve výuce na VUT v Brně
Kolářová, Jana ; Chmelíková, Larisa ; Kožíšek, Martin
Modelování fyzikálních polí je pro některé oblasti biomedicínského inženýrství stěžejní. Každý student elektrotechnického směru by se měl během svého studia seznámit alespoň se základními postupy návrhu simulací. Výuka simulací pomocí programového nástroje COMSOL Multiphysics se na Ústav biomedicínského inženýrství vrátila po delší odmlce díky podpoře firmy HUMUSOFT s.r.o. Kurz se nabízí jako volitelný v rámci předmětů studijních programů Fakulty elektrotechniky a komunikačních technologií a jako „svobodný předmět“ si ho mohou vybrat studenti napříč všemi fakultami VUT v Brně.
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Modeling electroacoustic systems in COMSOL
Hanuš, Jan ; Honzík,, Petr (referee) ; Schimmel, Jiří (advisor)
The thesis aims to explore the simulation software COMSOL Multiphysics with relevance to the field of electroacoustics. The work covers general introduction to the software, including an outline of the principles of finite element method, which is the most widely used numerical method in COMSOL Multiphysics. It also includes a clear description of the individual steps required to create a simulation. Furthermore, the Acoustics Module is described, Pressure Acoustics physics interface in particular as it is used later on in the simulations. The AC/DC Module and its physical interface Electric Circuit is mentioned briefly as well. Finally, the simulations created by the author are explained in a step-by-step manner. These look at the impact of the membrane’s and waveguide’s geometries on the radiation of the speaker driver, and the shapes of the loudspeaker system’s enclosure with the edge diffraction phenomena in mind. The results of the individual simulations are presented using graphs and discussed afterwards.
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Discrete modeling of nonlinear beams under uniform external load
Folorunsho, Sodiq Sunday ; Tomášek, Petr (referee) ; Giorgio, Ivan (advisor)
The concept of Beam theory is extensively studied in the fields of computational and structural mechanics, with widespread applications in both industry and academia. However, the existing body of knowledge lacks the derivation of important deformation equations due to the overly constrained assumptions made by early researchers in this area. This research aims to overcome these limitations by investigating beam deformation through the study of the centerline beam deformation theory, thus relaxing the previously adopted assumptions. To achieve this goal, the energy functionals variational formulation was employed to derive a classical formulation that avoids the inherent assumptions of the Euler-Bernoulli and Timoshenko beam model equations. A discrete approach, known as Hencky-Type, was utilized to verify the inextensibility constraint of the nonlinear Euler-Bernoulli Beam. Furthermore, the linearized case was derived using variational methods applied to its nonlinear counterpart. The derived models were then applied to two types of beams: the cantilever or clamped-Free (CF) beam and the simply supported beam (SS). A comparison was made to evaluate the superiority of these models. The nonlinear model formulation was solved using the weak formulation math model of COMSOL Multiphysics software. This study aims to pave the way for more accurate model formulations and the development of novel numerical schemes that can effectively handle nonlinear models, which are often avoided due to their complexity. The findings from this work hold the potential to significantly advance the field and facilitate the exploration of various practical applications.
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