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Nové metody záznamu chování volného proudu plazmatu užívající vláknovou optiku
Šonský, Jiří ; Hlína, Jan ; Něnička, Václav
The fibre optics coupling to photodiodes used in plasma jets optical radiation recording enables us to increase the channel count and to add flexibility to an experimental layout for multi-directional observations. These improvements give us opportunity of more detailed and important plasma jets behaviour analysis - reconstruction of luminosity fields (close to relative value of enthalpy) in planes perpendicular to a plasma jet axis, velocities and tracking of plasma jet axis movements. Details of experimental hardware and layount will be also shortly presented.
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Integrální přístup k řešení neferomagnetického elektrodynamického akcelerátoru
Karban, P. ; Doležel, Ivo
The paper deals with the description of dynamic behavior of a nonferromagnetic electrodynamic launcher. Although the problem itself is not new, an innovative item is determination of eddy currents in the launched body based on the integral approach that provides more accurate results than former algorithms of computation based on the FEM or electric circuit techniques. The methodology is illustrated on an example whose results are discussed
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Vybrané procesy v tekutých kovech řízené elektromagnetickým polem a jejich počítačová simulace
Mach, M. ; Doležel, Ivo
The paper presents some important results obtained by the authors during the three-year work in the domain of electromagnetic stirring and levitation melting. From the viewpoint of mathematical modeling both processes represent coupled problems characterized by mutual interaction of two or three physical fields, together with evaluation of various force effects. The theoretical analysis is illustrated on two typical examples whose results are discussed
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Nulová složka v třífázových asynchronních motorech
Schreier, Luděk ; Chomát, Miroslav
The paper deals with such a case of influence of zero-sequence component on the induction machine when this component arises due to connection of the stator winding neutral with the feeding source. The relationship between the zero-sequence component and the third space harmonic of stator current layer is shower. Furthermore, the paper deals with the methods of suppressing the undesirable influence of the zero-sequence component on the induction motor, especially an increase of additional losses and a rise of parasitic torques.
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Větvení obloukového kanálu ve vnějším magnetickém poli
Mrázek, Josef ; Hlína, Jan
An electric arc burning in mercury vapours exposed to external magnetic field changes its discharge path into a helix according to the Thomson principle of energy minimization. The voltage between the adjacent turns of the helix curvature may result in the critical electric field strenght in the vicinity of the arc channel, that leads to the branching and formation of a new discharge path acting as a turn-to-turn short. We have been interested in the electric field profile and surrounding parameters at the moment of branching, the speed of a new channel warming, temporal evolution of the restoration of a regular spiral channel, development of the arc current and distribution of the voltage between the series resistor and arc channel during the breakdown.
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