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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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Volcanic rocks and possibilities of their research using geophysical methods
Votrubcová, Kristýna ; Valenta, Jan (advisor) ; Vlček, Josef (referee)
5 Abstrakt (EN) The research focuses on the application of geophysical methods and subsequent data processing for the prospecting of igneous rocks and the search for volcanic structures. The literature review summarizes the physical and petrological foundations of various physical methods that can be utilized in the search for volcanic rocks, and discusses their most appropriate uses. The greatest emphasis is placed on the method of magnetometry, which is significant in identifying volcanoes. The work also explores the use of geoelectrical and seismic methods, radiometry, and gravimetry. In the practical section, geophysical measurements were conducted in the field to map the extent of the Tertiary volcano and other geological structures in the Elbe Sandstone Mountains. The extent of the volcanic body was successfully mapped using magnetic measurements. The results of the measured Electrical Resistivity Tomography (ERT) profile corresponded to the extent of the volcanite body and showed that the body was significantly fractured. Other findings include the mapping of a fault zone, to which the volcanic body ascend could be linked, and the mapping of another fault zone in a nearby valley, which is assumed to have a fault character. Key words: igneous rocks, volcanism, geophysics, magnetometry, VLF, ERT
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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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Geophysical prospection of volcanic structures, in the area of Rybí loučky, Jizerské mountains
Fait, Václav ; Valenta, Jan (advisor) ; Skácelová, Zuzana (referee)
This thesis briefly depicts fundamental principles of three geophysical methods (gravimetry, magnetometry and electrical resistivity profiling), which had been used during research at the Rybí lou ky site in order to clarify local geological conditions. Furthermore, the reader gets acquainted with formation of a maar-diatreme, which is thought to be present at the researched site. The next part describes principles of field measurements and the procedure for evaluation of results. The results are graphically plotted in the last part. Also, the results are compared to previous investigations conducted at this site. Geophysical measurements showed that geological structures on the Rybí lou ky site are much more complex than expected. The simple diatreme structure is most likely not applicable in this case. In contrast, it is not a structure formed solely by a glacier. The origin is most likely a combination of tectonic predisposition, volcanic activity and subsequent selective erosion.
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Výzkum sedimentů přehrad‚ nádrží a jezer - zhodnocení rizik a návrhy opatření
Česká geologická služba , Praha ; Müller, Pavel
Předmětem komplexního výzkumu jsou nádržní sedimenty, které jsou součástí jedné z významných složek životního prostředí. V těchto sedimentech byla zkoumána jejich kontaminace vybranými prvky a základními kategoriemi organických kontaminujících látek. Řešena byla i problematika zanášení nádrží a jejich eutrofizace včetně vymezení hlavních příčin. Součástí řešení projektu byly i pilotní aplikace některých progresivních metod výzkumu nádržních sedimentů (Radiometrie, magnetometrie, hustotní parametry. Byly předloženy i návrhy na zavedení a úpravu limitních kritérií a také návrhy na úpravu legislativy a způsobu nakládání s nádržními sedimenty včetně významného problému odbahňování rybníků. V prvním oddíle zprávy je uvedena charakteristika zkoumaného území, způsob výběru nádrží a rybníků, informace o počtech sond a vzorků z nádrží, zdrojích data a jejich prezentace. Druhý oddíl obsahuje metodiku odběrových prací a aplikované analytické metody. Další oddíl je věnován prezentaci výsledků podle jednotlivých nádrží a ostatních vodních děl. Následuje oddíl, ve kterém jsou diskutovány výsledky a zjištění vzešlá z analytické práce. Na závěr jsou uvedeny shrnující teze.
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