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Fine structure of quasiperiodic emissions observed in the Earth's magnetosphere
Partík, Vojtěch ; Němec, František (advisor) ; Bezděková, Barbora (referee)
Title: Fine structure of quasiperiodic emissions observed in the Earth's magne- tosphere Author: Vojtěch Partík Supervisor: doc. RNDr. František Němec, Ph.D. Abstract: Quasiperiodic emissions are a type of electromagnetic waves detected in the Earth's inner magnetosphere which are not yet fully understood. In this thesis, we use high resolution electric field data obtained by the DEMETER satellite, at an altitude of about 700 km, to analyze their fine inner structure. Overall, we analyzed 251 events, which were classified into three categories (with fine inner structure, without fine inner structure, and borderline cases). Additionally, we determined the periods of the fine inner structure and studied their dependance on relevant parameters. We show that the periods of the fine inner structure (on the order of seconds) do not significantly change during individual events and they are typically larger for events with longer modulation periods. We also show that the modulation periods of events without the fine inner structure are longer than the modulation periods of events with the fine inner structure, indicating their possibly different generation mechanisms. Keywords: DEMETER, quasiperiodic emissions, spectral analysis
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Electromagnetic Waves in Dispersiveand Refractive Relativistic Systems
Bezděková, Barbora ; Bičák, Jiří (advisor) ; Heyrovský, David (referee)
Study of light rays (light world lines) plays a significant role in many of astro- physical applications. Light rays are mainly studied in terms of so-called grav- itational lensing. However, the majority of studies are mainly focused on light propagation in vacuum. If the refractive and dispersive medium characterised by refractive index n is considered, effects occurring due to the medium presence need to be taken into account, which significantly complicates the problem. In the present thesis, rays propagating through simple refractive and dispersive systems, such as plane differentially sheared medium, are studied. In order to simplify the problem, the Hamiltonian equations of motion are used. The ray trajectories in the vicinity of Kerr black hole as well as accessible regions for the rays are also studied. Radial variation of the medium velocity is considered. Due to the recent increase of publications focused on the gravitational lensing in plasma, a detailed review summarizing the results obtained recently is included. 1
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Satellite observations of military transmitter signals
Pekař, Jan ; Němec, František (advisor) ; Bezděková, Barbora (referee)
Title: Satellite observations of military transmitter signals Author: Jan Pekař Department: Department of surface and plasma science Supervisor: doc. RNDr. František Němec, Ph.D., Department of surface and plasma science Abstract: Transmitters operating in the very low frequency range, used in military for their characteristic features, are powerful and localised sources of electromagnetic waves at known distinct frequencies. These waves can affect the ionosphere surrounding their passing as well as the dynamics of energetic particles trapped in the Van Allen radiation belts. A systematic analysis of data acquired by the low altitude satellite DEMETER in the vicinity of the transmitters and their magnetically conjugate regions during six years of its operation allows for the recognition and description of these potential influences. This work is focused primarily on changes of ionospheric plasma density and temperature and energetic particle precipitation due to wave-particle interactions. Keywords: Low frequency transmitters, DEMETER, ionosphere, particle precipitation
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Multipoint observations of magnetospheric wave phenomena
Bezděková, Barbora ; Němec, František (advisor) ; Grison, Benjamin (referee) ; Shklyar, David R. (referee)
Electromagnetic wave phenomena represent a crucial factor during the forma- tion of the Earth's magnetosphere, as they are responsible for the energy trans- fer in the collisionless plasma medium. Multipoint observations of such wave phenomena are particularly useful to distinguish between spatial and temporal intensity variations. Moreover, an approximate event spatial extent and prop- agation directions can be determined. The thesis is focused on the statistical study of conjugate observations of wave phenomena called quasiperiodic (QP) emissions observed by the Van Allen Probes spacecraft and ground-based Kan- nuslehto station. Altogether, 26 simultaneously observed events were analyzed. This approach is unique in the sense that most such analyses up to date were only case studies. The thesis further presents the analysis of the dependence of properties of another wave phenomena, called magnetospheric line radiation (MLR), on the geomagnetic activity indices and solar wind parameters. Geomag- netic activity effects on the event characteristics are revealed. Finally, the effect of interplanetary shocks on the overall very low frequency (VLF) wave intensity measured by the DEMETER spacecraft is studied.
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Electromagnetic Waves in Dispersiveand Refractive Relativistic Systems
Bezděková, Barbora ; Bičák, Jiří (advisor) ; Heyrovský, David (referee)
Study of light rays (light world lines) plays a significant role in many of astro- physical applications. Light rays are mainly studied in terms of so-called grav- itational lensing. However, the majority of studies are mainly focused on light propagation in vacuum. If the refractive and dispersive medium characterised by refractive index n is considered, effects occurring due to the medium presence need to be taken into account, which significantly complicates the problem. In the present thesis, rays propagating through simple refractive and dispersive systems, such as plane differentially sheared medium, are studied. In order to simplify the problem, the Hamiltonian equations of motion are used. The ray trajectories in the vicinity of Kerr black hole as well as accessible regions for the rays are also studied. Radial variation of the medium velocity is considered. Due to the recent increase of publications focused on the gravitational lensing in plasma, a detailed review summarizing the results obtained recently is included. 1
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Transfer of undertakings in selected EU member states
Bezděková, Barbora ; Drápal, Ljubomír (advisor) ; Morávek, Jakub (referee)
The topic of the doctoral thesis is the regulation of passage of rights and obligations under employment relationship, i.e. the regulation that aims to safeguard the rights of employees in the event of structural changes of their employers. The first chapter introduces the legal regulation adopted by the European Union, the Council Directive 77/187/EEC of 14 February 1977 on the approximation of the laws of the Member States relating to the safeguarding of employees' rights in the event of transfers of undertakings, businesses or parts of businesses and the amended Council Directive 2001/23/EC of 12 March 2001 on the approximation of the laws of the Member States relating to the safeguarding of employees' rights in the event of transfers of undertakings, businesses or parts of undertakings or businesses, that harmonized the standards of employees' protection in the event of transfer of undertakings, including the historical background. Particular emphasis is placed on the relevant case law of the Court of Justice of the European Union interpreting the directives. In the next chapters of the thesis three national legislations of the member states of the European Union are subsequently analysed - the Czech, French and British law. The foreign regulations were chosen for comparison based on their...
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Selected Wave Phenomena in the Earth's Magnetosphere
Bezděková, Barbora ; Němec, František (advisor) ; Macúšová, Eva (referee)
Electromagnetic waves are crucial for energy transfer in the nearly collision- less plasma of the Earth's inner magnetosphere. The waves in the frequency range 1-8 kHz whose visualisation in the form of frequency-time spectrograms reveals a harmonic frequency modulation of the wave intensity are called magnetospheric line radiation (MLR). Waves characterized by a nearly periodic time modulation of the wave intensity observed at frequencies between about 0.5 and 4 kHz are called quasiperiodic (QP) emissions. Although both types of the events were re- peatedly observed by ground-based instruments and low-altitude satellites, their origin remains still unclear. Between 2004 and 2010 these wave events were me- asured by the DEMETER spacecraft (almost Sun-synchronous orbit, altitude of about 700 km). This thesis presents a systematic study of the properties of the observed events, a comparison of the observations by the spacecraft and ground- based instruments, and an investigation of a relation to solar wind parameters.
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Employment tribunals and courts in selected EU member states
Bezděková, Barbora ; Drápal, Ljubomír (advisor) ; Štefko, Martin (referee)
The thesis deals with the regulation of individual labour disputes settlement provided for in the law systems of the EU member states. The law systems chosen for comparison are the ones of the Czech Republic, England and France. In the first chapter there is an outline of the obligations resulting from the international and European legislation in the area of labour disputes settlement. In the following three chapters the Czech, English and French regulations are described subsequently. The individual regulations of the above mentioned countries are analyzed with reference to the institutions endowed with authority to settle individual labour disputes, the participation of lay members in the process of decision making, the proceedings at the courts of first instance as well as the proceedings at the higher courts and last but not least with reference to the means of alternative dispute settlement. In the second chapter dedicated to the Czech regulation the historical context is also mentioned. In the final part of the thesis the results of the analysis are compared and suggestions for the future Czech regulation of labour disputes settlement are offered.
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Magnetospheric line radiation observed by the DEMETER spacecraft
Bezděková, Barbora ; Němec, František (advisor) ; Sochorová, Zuzana (referee)
Frequency-time spectrograms of electromagnetic waves observed in the Earth's inner magnetosphere in the frequency range 1-8 kHz sometimes contain nearly horizontal and almost parallel intense lines. Such events were observed both by ground-based instruments and satellites, and they are called Magnetospheric Line Radiation (MLR). We systematically analyze 1230 MLR events identified in the data of the DEMETER spacecraft (2004-2010, altitude of about 700 km). We focus on a possible connection between the event occurrence and solar wind parameters. Long analyzed data interval allows us to evaluate a possible influence of the solar cycle and season of the year. We show that there is a statistically significant correlation between MLR events and solar wind parameters, and that the events are observed more often during the winter months and preferably during the solar maximum. The events occur less frequently at geomagnetic longitudes of South Atlantic Anomaly (SAA). We analyze spectra of energetic electrons precipitating in this region at the times of MLR events, which are supposed to be related to the wave generation. Powered by TCPDF (www.tcpdf.org)
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