Bitcoin and Its Position on Financial Markets

Import 22/07/2015Cílem této bakalářské práce je empiricky ověřit vliv finančních a makroekonomických ukazatelů na vývoj ceny Bitcoinu. Naplnění tohoto cíle je dosaženo pomocí vědeckých metod syntézy a deskriptivní a korelační analýzy. Důvodem pro ověřování byla skutečnost, že většina autorů prováděla svoji analýzu před téměř dvěma roky, což v případě Bitcoinu představuje dávnou minulost. Vliv konkrétních finančních a makroekonomických indikátorů na cenu Bitcoinu byl nejprve ověřen v dlouhém období, které vzniklo prodloužením původního období použitého v jiné předchozí práci. V tomto období byl potvrzen vztah mezi cenou Bitcoinu a hodnotou Dow Jones indexu. Nepotvrdila se předchozí koncepce závislosti mezi cenou Bitcoinu a hodnotou směnného kurzu USD/EUR, resp. cenou ropy. V tomto období byla rovněž objevena nepřímá závislost mezi cenou Bitcoinu a cenou zlata. V samostatné podkapitole byl pak ověřen vliv všech těchto veličin na cenu Bitcoinu v krátkém období.The aim of this bachelor thesis is to empirically check the influence of financial and macroeconomic indicators on Bitcoin price. This is achieved by using synthesis and descriptive and correlation analysis as the main scientific methods. The reason for the research was that the majority of authors have done their analysis almost two years ago, which in case of Bitcoin means a very long time. First, the influence of specific financial and macroeconomic indicators on Bitcoin price has been checked in the long run (a period that was created by prolonging the period used in previous literature). In this period the relationship between Bitcoin price and Dow Jones Index value has been confirmed. The previous concept of Bitcoin price and its dependence on USD/EUR exchange rate value and oil price respectively has not been confirmed. A negative correlation between Bitcoin price and gold price has been discovered. After that the influence of all these indicators on Bitcoin price has been checked for the short run as well.156 - Katedra národohospodářskávelmi dobř

Temperature dependence of magnetization processes in Sm(Co, Fe, Cu, Zr)z magnets with different nanoscale microstructures

The characteristic microstructure of Sm (Co, Fe, Cu, Zr) z (z = 6.7 - 9.1) alloys with SmCo 5 cell walls in Sm 2 Co 17 cells, all intersected by Zr-rich platelets, makes them some of the best performing high-temperature permanent magnets. Plentiful research has been performed to tailor their microstructure at the nanoscale; but due to its complexity, many questions remain unanswered about the effect of the individual phases on the magnetic performance at different temperatures. Here, we explore this effect for three different Sm (Co, Fe, Cu, Zr) z alloys by deploying high-resolution magnetic imaging via in situ transmission electron microscopy and three-dimensional chemical analysis via atom probe tomography. We show that their microstructures differ in terms of SmCo 5 cell-wall and Z-phase size and density as well as the Cu concentration in the cell walls and demonstrate how these features influence the magnetic domain size and density, thus forming different micromagnetic spin structures. Moreover, we illustrate that the dominant coercivity mechanism at room temperature is domain-wall pinning and show that magnets with a denser cell-wall network, a steeper Cu gradient across the cell-wall boundary, and thinner Z-phase platelets have a higher coercivity. We also show that the coercivity mechanism at high temperatures is domain-wall nucleation at the cell walls. Increasing the Cu concentration inside the cell walls decreases the temperature of transition between pinning and nucleation, significantly decreasing the coercivity with increasing temperature. We, therefore, provide a detailed explanation of how the microstructure on the atomic to nanoscale directly affects the magnetic performance and provide detailed guidelines for an improved design of Sm (Co, Fe, Cu, Zr) z magnets.ISSN:0021-8979ISSN:1089-755

Unconventional magnetization textures and domain-wall pinning in Sm–Co magnets

Some of the best-performing high-temperature magnets are Sm–Co-based alloys with a microstructure that comprises an Sm2Co17 matrix and magnetically hard SmCo5 cell walls. This generates a dense domain-wall-pinning network that endows the material with remarkable magnetic hardness. A precise understanding of the coupling between magnetism and microstructure is essential for enhancing the performance of Sm–Co magnets, but experiments and theory have not yet converged to a unified model. Here, transmission electron microscopy, atom probe tomography, and nanometer-resolution off-axis electron holography have been combined with micromagnetic simulations to reveal that the magnetization state in Sm–Co magnets results from curling instabilities and domain-wall pinning effects at the intersections of phases with different magnetic hardness. Additionally, this study has found that topologically non-trivial magnetic domains separated by a complex network of domain walls play a key role in the magnetic state by acting as nucleation sites for magnetization reversal. These findings reveal previously hidden aspects of magnetism in Sm–Co magnets and, by identifying weak points in the microstructure, provide guidelines for improving these high-performance magnetic materials