This thesis focuses on the study of spectral stability of planar shock waves in 2-dimensional magnetohydrodynamics. We begin with a numerical approach, computing the Lopatinski determinant and Evans function with the goal of determining if there are parameters for which viscous waves are unstable and the corresponding inviscid waves are stable. We also begin developing a method to obtain an explicit, analytical representation of the Evans function. We demonstrate the capabilities of this method with compressible Navier-Stokes and extend our results to 2-D MHD. Finally, using compressible Navier-Stokes again, we derive an energy estimate as a first step in improving the bound on possible roots of the Evans function.

The Richtmyer-Meshkov instability occurs when density-stratified interfaces are impulsively accelerated, typically by a shock wave. We present a numerical method to simulate the Richtmyer-Meshkov instability in cylindrical geometry. The ideal MHD equations are linearized about a time-dependent base state to yield linear partial differential equations governing the perturbed quantities. Convergence tests demonstrate that second order accuracy is achieved for smooth flows, and the order of accuracy is between first and second order for flows with discontinuities. Numerical results are presented for cases of interfaces with positive Atwood number and purely azimuthal perturbations. In hydrodynamics, the Richtmyer-Meshkov instability growth of perturbations is followed by a Rayleigh-Taylor growth phase. In MHD, numerical results indicate that the perturbations can be suppressed for sufficiently large perturbation wavenumbers and magnetic fields.

Diploma thesis maps functioning, problems and troubles of public transportation in Prague during socialism in years 1948 till 1974. These years represents the beginning of communism in Czechoslovak Republic and year of putting the Prague metro into operation. The aim of the work was to examine this limited period in terms of public transportation, its impact on urban development, how different types of public transportation interacted and complemented each other, what was its impact on passengers alone and , for example, how metro planning during this period affected the operation of busses, troleybusses and trams. We found that despite the fact that the metro was at first just an unnecessary plan, later the entire system of public transportation began to concentrate and change precisely because of its implementation. Key words: Public transportation, trams, buses, metro, city development

NR 20140805

Spectral indices and flatness scaling exponents corresponding to solar wind plasma measurements before, during and after a coronal mass ejection (CME) detected by NASA's Wind spacecraft on September 2014 have been obtained. The Politano-Pouquet (PP) law for isotropic and incompressible magnetohydrodynamic (MHD) turbulence has been validated over a series of selected time intervals. The performed analysis showed that turbulence was well established within most of such intervals and several mean energy transfer rates were computed. Furthermore, the results detailed in this essay suggest possible correlations between the aforementioned energy transfer rates and the spectral indices and flatness scaling exponents, and also between enhanced intermittencies and large values of the mean energy transfer rates.

In the present work we study the properties of accretion tori orbiting black hole. Our approach to this problem comes from the solving of general relativistic magnetohydrodynamic equations, which follow from conservation of the energy-momentum tensor, the particle number and from Maxwell's equations. We solve these equations by numerical methods which are described in Chapter 1. The formalism of tori which we consider here is described in Chapter 2. We are interested in tori with constant density of angular momentum and Fishbone-Moncrief tori mainly. We study accretion rates in these tori when the mass of black hole is increased suddenly and so the equilibrium in the torus is corrupted. For tori with constant density of angular momentum we study the influence of the presence of toroidal magnetic field on accretion rates.

京都大学 / 0048 / 新制・論文博士 / 博士(理学) / 乙第12813号 / 論理博第1539号 / 新制||理||1577(附属図書館) / 31300 / (主査)教授 嶺重 慎, 准教授 前田 啓一, 教授 長田 哲也 / 学位規則第4条第2項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20089号 / 工博第4256号 / 新制||工||1659(附属図書館) / 33205 / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 大村 善治, 教授 松尾 哲司, 准教授 小嶋 浩嗣 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20919号 / 理博第4371号 / 新制||理||1627(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 嶺重 慎, 准教授 前田 啓一, 教授 太田 耕司 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21764号 / 工博第4581号 / 新制||工||1714(附属図書館) / 京都大学大学院工学研究科原子核工学専攻 / (主査)教授 功刀 資彰, 教授 横峯 健彦, 教授 村上 定義 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM