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S Band Antennas for Cubesat Satellites
Bekeč, Alexander ; Cupal, Miroslav (referee) ; Urbanec, Tomáš (advisor)
This bachelor’s thesis is dedicated to antennas designed for use onboard miniaturized satellites CubeSat. The main goal of the thesis was to examine suitable antennas working in the S-band for use onboard this type of satellites, create their models and simulate them in the software ANSYS HFSS together with the CubeSat frame to find out its impact on the characteristics of antennas. One of these antennas was constructed together with CubeSat frame and measured in the RF anechoic chamber. Besides these, different types of satellite attitude stabilisation were examined, along with their influence on communication with ground station. Minimal half power beamwidths of antennas were analysed for both studied types of single axis stabilisation with consideration of communication with ground station located in the city of Brno.
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Mechanical design of rotary satellite antenna polarization system
Vítek, Petr ; Mazal, Pavel (referee) ; Paloušek, David (advisor)
The aim of this bachelor thesis is mechanical design of rotary satellite antenna polarization system. It is a part of a mobile satellite antenna positioned on the roof rack of a passenger car. Device must be designed to achieve precise positioning and smooth running. It must also resist moisture and temperature fluctuations. For this application, there has been selected and developed solution with toothed belt. The thesis includes a selection algorithm of drive, belt and bearings. The achieved polarization angle is 180 °. The results of this paper can be used to produce a functional mobile satellite antenna polarization.
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Disinformation in France: A Strategy of Information Warfare in the Digital Age
Bourdas, Annabelle Marie Amelie ; Střítecký, Vít (advisor) ; Scotto, Thomas (referee)
Political elections are a fertile ground for disinformation campaigns to prosper as have shown studies on Brexit and the 2016 US elections. The 2022 presidential French elections took place in a particular setting due to the social and political context marked by the rise of far-right parties and movements as well as the succession of crises such as the 2015 terrorist attacks, 2018 yellow vests movement, the Covid-19 pandemic and the war in Ukraine. This context and the health crisis in particular have given a new lease of life to far-right movements. Indeed, they spread disinformation, mainly on social media, on the pandemic and fuelled anti-system feelings to advance their agenda. In this context, the far-right political candidate to the 2022 elections, Éric Zemmour, a famous polemicist, thrived and managed to impose himself in the national political landscape. He did so notably by using discursive practices and his media presence. As a result, there has been a banalisation of far-right rhetoric and conspiracy theories in society. This has two major consequences: first, the undermining of democratic and electoral processes and second, the risk of a resurgence of domestic terrorism. Therefore, disinformation is a threat for democracies as they exacerbate social tensions and divisions which can...
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Effect of statin treatment on macrophage polarisation in vitro
Muffová, Barbora ; Kauerová, Soňa (advisor) ; Krulová, Magdaléna (referee)
Statins are widely used for their eminent hypolipidemic effect as anti-atherosclerotic drugs from the 90's of the 20th century. Even though there are new approaches, statins are still the first choice in the prevention of cardiovascular diseases. At the beginning of the 21st century, the anti- inflammatory effect independent of lipid-lowering properties was discovered. This diploma thesis deals with the effect of statin treatment on macrophage polarisation in vitro. Macrophages differentiated from blood monocytes were used in this thesis. The effect of statin treatment on the expression of surface markers (CD16, CD15, CD36, CD163, CD206, ABCA-1 and Trem-2) was evaluated by flow cytometry. The qPCR method was used to quantify the effect of statin treatment on the gene expression of inflammatory genes (NFκB, IL-1β, IL-6, TNFα and iNOS), anti- inflammatory genes (Arg-1, TGFβ) and genes which play a role in the adhesion and migration of monocytes and macrophages to vessel intima (VCAM-1 and MCP-1). Griess method was used to evaluate the effect of statin treatment on the inducible NO-synthase activity. Last, but not least, the effect of statin treatment on proteosynthesis of inflammatory cytokines (IL-1β, IL-6 a TNFα) and anti-inflammatory cytokine IL-10 was measured. Flow cytometry results show that...
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S Band Antennas for Cubesat Satellites
Bekeč, Alexander ; Cupal, Miroslav (referee) ; Urbanec, Tomáš (advisor)
This bachelor’s thesis is dedicated to antennas designed for use onboard miniaturized satellites CubeSat. The main goal of the thesis was to examine suitable antennas working in the S-band for use onboard this type of satellites, create their models and simulate them in the software ANSYS HFSS together with the CubeSat frame to find out its impact on the characteristics of antennas. One of these antennas was constructed together with CubeSat frame and measured in the RF anechoic chamber. Besides these, different types of satellite attitude stabilisation were examined, along with their influence on communication with ground station. Minimal half power beamwidths of antennas were analysed for both studied types of single axis stabilisation with consideration of communication with ground station located in the city of Brno.
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Polarisation of X-ray emission from accretion discs in active galactic nuclei
Podgorný, Jakub ; Dovčiak, Michal (advisor) ; Marin, Frédéric (referee)
The presented thesis deals with theoretical modeling of the X-ray emission from active galactic nuclei. It studies spectral and polarisation properties of local radiation reflected from the surrounding accretion disc, which is being illuminated by a hot corona above, as well as global observational perspectives at infinity for unobscured radio-quiet sources. Modeling of this kind could then serve for observational fitting of spin of the central supermassive black hole, constraining the accretion disc's or coronal properties, or de- termining observer's inclination towards the systems. A radiative transfer Monte Carlo simulation code STOKES [Goosmann and Gaskell, 2007, Marin et al., 2012, 2015, Marin, 2018] is used for local computations. Its performance is compared to results of other attempts already existing in literature and analytical approximations. The local scheme is discussed mostly in terms of emergent polarisation that has been for the first time simulated for these types of objects with high accuracy. Integration over the accretion disc and superposition with the primary radiation in the so-called lamp-post or extended coronal model, including all general relativistic effects in the vicinity of the central super- massive black hole, is then performed on the basis of already existing routine...
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Polarisation of X-ray emission from accretion discs in active galactic nuclei
Podgorný, Jakub ; Dovčiak, Michal (advisor)
The presented thesis deals with theoretical modeling of the X-ray emission from active galactic nuclei. It studies spectral and polarisation properties of local radiation reflected from the surrounding accretion disc, which is being illuminated by a hot corona above, as well as global observational perspectives at infinity for unobscured radio-quiet sources. Modeling of this kind could then serve for observational fitting of spin of the central supermassive black hole, constraining the accretion disc's or coronal properties, or de- termining observer's inclination towards the systems. A radiative transfer Monte Carlo simulation code STOKES [Goosmann and Gaskell, 2007, Marin et al., 2012, 2015, Marin, 2018] is used for local computations. Its performance is compared to results of other attempts already existing in literature and analytical approximations. The local scheme is discussed mostly in terms of emergent polarisation that has been for the first time simulated for these types of objects with high accuracy. Integration over the accretion disc and superposition with the primary radiation in the so-called lamp-post or extended coronal model, including all general relativistic effects in the vicinity of the central super- massive black hole, is then performed on the basis of already existing routine...
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Polarisation of X-ray emission from accretion discs in active galactic nuclei
Podgorný, Jakub ; Dovčiak, Michal (advisor) ; Marin, Frédéric (referee)
The presented thesis deals with theoretical modeling of the X-ray emission from active galactic nuclei. It studies spectral and polarisation properties of local radiation reflected from the surrounding accretion disc, which is being illuminated by a hot corona above, as well as global observational perspectives at infinity for unobscured radio-quiet sources. Modeling of this kind could then serve for observational fitting of spin of the central supermassive black hole, constraining the accretion disc's or coronal properties, or de- termining observer's inclination towards the systems. A radiative transfer Monte Carlo simulation code STOKES [Goosmann and Gaskell, 2007, Marin et al., 2012, 2015, Marin, 2018] is used for local computations. Its performance is compared to results of other attempts already existing in literature and analytical approximations. The local scheme is discussed mostly in terms of emergent polarisation that has been for the first time simulated for these types of objects with high accuracy. Integration over the accretion disc and superposition with the primary radiation in the so-called lamp-post or extended coronal model, including all general relativistic effects in the vicinity of the central super- massive black hole, is then performed on the basis of already existing routine...
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Mechanical design of rotary satellite antenna polarization system
Vítek, Petr ; Mazal, Pavel (referee) ; Paloušek, David (advisor)
The aim of this bachelor thesis is mechanical design of rotary satellite antenna polarization system. It is a part of a mobile satellite antenna positioned on the roof rack of a passenger car. Device must be designed to achieve precise positioning and smooth running. It must also resist moisture and temperature fluctuations. For this application, there has been selected and developed solution with toothed belt. The thesis includes a selection algorithm of drive, belt and bearings. The achieved polarization angle is 180 °. The results of this paper can be used to produce a functional mobile satellite antenna polarization.
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