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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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Simulation of toroid coils in Ansoft Maxwell 3D
Daněk, Michal ; Pfeifer, Václav (referee) ; Hanák, Pavel (advisor)
The master thesis is focused on the simulation of the toroid coils in Ansoft Maxwell 3D software, which uses finite element method for electromagnetic field simulation. Firstly the process creation of the geometric model toroid coil with seventy-five threaded is presented. It is necessary to debug this model and prepare it for the mesh generation. Physical properties are assign to this model and it gives rise to the physical model. We will set boundaries, excitation current, core material, winding material and the parameters for the mesh generations. New material Kashke K4000 will be created in the materials library and subsequently we will define its BH curve on the basis of datasheet. Analysis is made in two modes. Direct currents (7,5A; 10A; 15A; 20A; 25A) and (non)linear materials are used in magnetostatic solution. Toroid coil is excited by current pulse in transient solution. In Ansoft Maxwell Circuit editor a source which generates current pulse will be created. This excitation will be assigned to the toroid coil as an extern source through a terminal. Core material is linear in the case of transient analysis, because Ansoft Maxwell 3D doesn´t allow to use nonlinear material in this solution. Settings are different in transient and in magnetostatic analysis. End time and time step are entered to solve this task in transient analysis. Time points are entered too. Flux density and electromagnetic field strength are calculated in these time points and later it will be possible to view the results. Calculated fields are shown as the pictures in this thesis. The procedure how to use a field calculator in the postprocessing is given as well. The achievements are summarized in the conclusion.
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Workplace for HF Radiated Immunity Testing
Slach, Petr ; Soldán, Josef (referee) ; Svačina, Jiří (advisor)
This thesis investigates into possibilities of a design of a workplace for device endurance experiments against strong high-frequency electromagnetic field. It deals with testing methods, describes advantages and disadvantages of such methods. It investigates possibiities of testing devices, possible magnitudes of fieldstrenght. One can find in the thesis a review of a way of testing using a high-intensity electromagnetic field. A concept of a construction of a stripline including a practical example is a part of the thesis.
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Measurement of anechoic chambers
Švec, Marek ; Nováček, Zdeněk (referee) ; Dřínovský, Jiří (advisor)
This Master’s project deals with general aspects and possible solution of effective shielded cover and cell/chamber shielding measurement for needs of electromagnetic compatibility EMC on the basis of available norms and standards. Electromagnetic shielding is one of the most anticlutter means of EMC. Its main task is reduction of disturbing emission at the side of sources of disturbing signals as well as electromagnetic resistance increase at the side of disturbing signal receivers. Shielding is considered to be an important structural means to reduce electromagnetic field referring to a defined space part. Technical means for achieving the given goals are called shielded covers or shielded cells/chambers. Shielding is one of highly effective methods related to electromagnetic protection, for instance against power/output disturbance. To express the shielding quality so called shielding effectiveness SE is used. It represents logarithmic rate of shielding coefficient that is defined by the intensity ratios of electric and magnetic fields in a certain point of the shielded space to electric or magnetic field intensity incident/impinging on the shielded screen or wall.
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Broadband Linear Antenna Array for BAN Applications
Gaja, T.
The work deals with antenna array for application in BAN. The main attention is focused on the shaping of radiation pattern. The paper describes the principles of the designing antenna arrays with desired radiation patterns. Based on these principles the script was created in environment MATLAB which effectively analyses features of each desired antenna array. The next section of this work is focused on design of broadband Vivaldi antenna array in frequency band 4.6 – 6.6 GHz. Designed antenna array was verified in simulator of electromagnetic field CST. The antenna array was also analyzed in proximity of human tissue.
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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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Statické charakteristiky konstrukčních částí řiditelného termoelastického aktuátoru
Doležel, Ivo ; Kotlan, V. ; Ulrych, B.
The paper deals with one of the basic conditions of practical employment of finely controllable thermoelastic actuators – problems of the static characteristics of its individual structural parts. It contains the formulation of the principle of such thermoelastic actuators, description of its components (a dilatation element heated by induction, auxiliary electromagnetic actuators, and self-locking friction clutches) and their mathematical models. Briefly discussed are also their corresponding computer models making use of the finite element method. The crucial point of the work consists in the presentation of the results – static characteristics of the considered structural parts of the controlled thermoelastic actuators.
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