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Elektromagnetic field mapping in tissue
Port, Martin ; Čížek, Martin (referee) ; Rozman, Jiří (advisor)
This thesis is an introduction to the modeling of electromagnetic fields in the tissue and is focused on the knowledge of electromagnetic field theory. Maxwell's equations and their solutions are described the spread of plane waves in the environment. It also discusses the exposure limit values of specific absorbed power and hygienic limits based on the standards in force in the Czech Republic on health protection against nonionizing radiation in accordance with Government Regulation No. 106/2010 Coll. It also deals with the software interface in COMSOL Multiphysics 4.2 for solving physical modeling and simulation. There is mention of the RF module, which is used for modeling. Work mentions in detail about the menu of the program and the most important part - the Model Builder.
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Geodetic structure of multi-black-hole spacetimes
Ryzner, Jiří ; Žofka, Martin (advisor) ; Svítek, Otakar (referee)
V klasické fyzice m·že být ustavena statická rovnováha v soustavě nabitých hmotných bod·, jsou-li poměry náboje a hmotnosti každého hmotného bodu stejné. Udivujícím faktem je, že tato situace m·že nastat i pro černé díry v relativistické fyzice. Obecný případ takovéhoto systému poprvé popsali Majumdar a Papapetrou nezávisle na sobě v roce 1947. Tato práce se zabývá jeho speciálním případem obsahujícím dvě nabité černé díry, zkoumá elektrogeodetiky v tomto prostoročasu a srovnává je se situací v klasické fyzice. Dále též shrnujeme situaci v případě nestatického vesmíru, kterou popsali Kastor a Traschenová v roce 1992, a tuto geometrii srovnáváme se statickou verzí. 1
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Light propagation in magnetic materials
Wagenknecht, David ; Ostatnický, Tomáš (advisor) ; Veis, Martin (referee)
Transparent magnetic materials, among the others semiconductors, have recently come to the focus of interest in both basic and applied research because they have great potential in optical applications and they can be used in optical spectroscopy to investigate fundamental physical phenomena. The theoretical calculations introduce that these materials have some extraordinary properties like asymmetric reflectance when light impact the sample from the opposite angles. In this bachelor thesis, transfer matrix formalism is derived based on Maxwell equations, taking into account special form of effective permittivity. The reflection coefficient for one layer demonstrates, that the asymmetric reflectance appears for transversal- magnetic polarization of light and transversal magnetization in the studied material. The derived formulae are used to calculate the difference in reflectivities for the waves impacting the structure from opposite angles. Ga1−xMnxAs with different concentrations of manganese is assumed to be the essential transparent magnetic layer in the sample. 1
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Konečné prvky v elektromagnetismu kompatibilní s De Rhamovým diagramem
Rybář, Vojtěch ; Doležel, Ivo (advisor) ; Vejchodský, Tomáš (referee)
Title: Finite elements for electromagnetics compatible with de Rham di- agram Author: Vojtěch Rybář Department: Department of Numerical Mathematics Supervisor: prof. Ing. Ivo Doležel, CSc. Abstract: The present work is devoted to the lowest-order finite elements for solving time-harmonic Maxwell's equations in two dimensions. Suc- cessful approximation of these equations requires the finite element spaces to be compatible with the de Rham diagram. However, the most often used basis functions (the Whitney functions) do not comply with this diagram. Therefore, we construct compatible bases and study their prop- erties. Since the construction is not unique, we investigate the influence of the particular choice on the conditioning of the corresponding finite element matrices. Finally, we utilize the special structure of the stiffness matrices, propose a few iterative schemes, and compare their convergence. Keywords: Maxwell's equations, edge finite element, de Rham diagram, finite element basis 1
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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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Wireless transfer of energy
Varga, David ; Koňas, Petr (referee) ; Steinbauer, Miloslav (advisor)
ork tie together on first project, in which the was designed apparatus for tests wireless transmission energy. Antenna was synthesized and theoretically optimized for experimental operation, in which the will performed series measuring. In first part is practical description of realization proposal. It consists of circuital solution, proposal measuring workplace and mechanical construction with illustration photographs of arrangement. Second part includes results of performed measuring. These measuring will divided by three basic groups: in first group will by testing feature one’s antennae, in second group will series transmission measuring power gain, and in third group will photographed shape of field, and comparison with simple simulation finite difference method. Third part summarises results from measuring, and prepares consecutive balancing visualisation project, which is of thematic bent on chosen aspects theoretical hypothesis and effected experiments.
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Electromagnetic field mapping in biological tissues
Bereznanin, Martin ; Dlouhý, Jiří (referee) ; Rozman, Jiří (advisor)
The main objective of this study is to learn about the theory of electromagnetic field and to create a model of propagation of ultra short waves in a biological tissue. Next point of this paper is to determine a specific absorption rate (SAR) using a valid sanitary standard. A particular model solution was realized in a model environment of the program Comsol Multiphysics 3.5. A human head and a cellular phone with an intern antenna were successfully created in this model environment. First of all were entered appropriate parameters which led to a successful representation of the distribution of electric field intensity. A value of specific absorption rate taken by a biological tissue was determined in the next step. This value was compared to the value listed in a valid sanitary standard to prevent its overrun. A development of a temperature in a biological tissue was determined as well, according to a six minutes long interval stated in a valid sanitary standard.
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The theory of electromagnetic field for radiological assistants
PEŠKOVÁ, Lucie
Currently is not freely available any simple educational text on the topic of the theory of electromagnetic field, which would be adequate to the student´s knowledge of the Radiology assitents subject and futher related subjects. This work defines this following goals: to create the expected, project and implement curriculum in the area of the electromagnetic field for radiolgy assistants and the verification of the adequacy of the project´s curriculum with the help of the experimental education and the statistical result´s evaluation of the verification with the questionnaire survey. The practical contribution of the bachelor´s work is the made educational text with the PowerPoint presentation, which is possible to use for the teaching of the theory of electromagnetic field. The theoretical contibution of the bachelor´s work is the excuse of the theory of curricular process on the area of the theoretical basis of the electromagnetic field under the therms of education of radiology assistents and next potential applicants of radiology.
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Magnetic Resonance and its Electromagnetic Essence
MOLÁKOVÁ, Markéta
This fact is reflected in the aims of the thesis, which lie in using the Curricular Process Theory and the already researched quantum dimension of magnetic resonance for defining the electromagnetic foundation of magnetic resonance in such a form that would be suitable for students of "Radiology assistant" and other related programs. Considering the set aims and the use of applied quantitative research, the thesis presents the following hypotheses: 1) It is possible to create an educational text for students of "Radiology assistant" and related study programs by applying the Curricular Process Theory. 2) The distribution of respondents' knowledge will have a theoretical distribution similar to the normal distribution. First, it was necessary to analyse the current state of research on the subject of "Electromagnetic foundation of magnetic resonance for radiology assistants" based on the Curricular Process Theory. The present study examines the Electromagnetic Field Theory, especially the description and deduction of Maxwell's four equations for electromagnetic field, defines mathematical operators needed for describing Maxwell's equations, describes the causes of changes in electric and magnetic fields (wells and vortices), and also mathematically proves that the electromagnetic field spreads in the air a s a wave. Then, it was needed to adjust the form of these physical facts to students of "Radiology assistant" and other related study programs. It resulted in creating a simple educational text (see Appendix 1), whose suitability for the educational target group was verified by a statistical evaluation. Consequently, the first hypothesis that it is possible to create an educational text for students of "Radiology assistant" and related study programs by applying the Curricular Process Theory was confirmed. The functionality of the educational text was verified by an experimental seminar. The seminar was organised for the students of "Radiology assistant" study program at The Faculty of Health and Social Sciences at the University of South Bohemia in České Budějovice and it was accompanied by a PowerPoint presentation. The students who did not participate in the seminar were sent the educational text (and test) in the electronic form. In order to verify the knowledge gained during the experimental seminar and from the educational text, the defined electromagnetic foundation (educational text) was reflected in a test with 13 questions with four alternative options for each there was only one correct option for each question. The test was taken by respondents and the results were statistically evaluated. The type of research used in the thesis is applied quantitative research. The verification of the hypotheses was based on the use of appropriate methods of descriptive and mathematical statistics as well as the use of non-parametric testing, the so called Pearson Chi-Square test (Goodness of Fit). On the whole, 35 tests were processed. Empirical frequency distributions obtained by scoring the tests were matched with the so called Gaussian distribution. Thanks to the use of non-parametric testing, it was possible to confirm the second hypothesis that the distribution of respondents' knowledge will have a theoretical distribution similar to the normal distribution. Therefore, the statistical evaluation confirmed that the educational text is suitable for the needs and possibilities of the respondents and their knowledge distribution is close to the normal distribution. The acquired results show that the knowledge of the respondents was in agreement with the expected assumption of the normal distribution.
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