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Porovnání magnetického pole vně a uvnitř trolejbusu 21 Tr řízeného GTO nebo IGCT tyristorem
Nečesaný, Jakub ; Doležel, Ivo
This work is focused on the magnetic field modelling and analysis inside the trolley bus 21TR. Mathematical description is presented. Computation is carried out for accelerating regime for application of two different power switching semiconductor devices GTO and IGCT. Study of the magnetic field is done for head level of standing and sitting people. Local maximum of the magnetic field is also determined. Differences between magnetic field levels given by GTO and IGCT power switching semiconductor devices are consecrated. Finally, geometrical convergence of this problem is evaluated
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Posuvný indukční ohřev a související jevy v kvazi-sdružené formulaci
Karban, P. ; Ulrych, B. ; Doležel, Ivo
The paper deals with quasi-coupled numerical solution of the problem of induction heating and associated phenomena in 2D axisymmetric arrangements. The process of heating is modeled by a special algorithm respecting the temperature dependencies of various material properties and (when necessary) time variable boundary conditions. The algorithm fully developed by the authors is illustrated on an example of continual induction hardening
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Power Electronics and Quality of Electrical Energy
Valouch, Viktor
The paper deals with basic problems concerning the application of power electronic converters in the field of electric power engineering with the aim of improving power quality in transmission and distribution systems. The attention is focused mainly on questions of converter power circuits, their control algorithms, and on modeling and simulation of respective systems. Basic power theories are mentioned as well.
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Alternative Utilisation of a Matrix Converter
Flígl, S. ; Lettl, Jiří
The matrix converter seems to be the final name of one of the older static direct frequency changer power electronics circuit configuration, which finds once again new utilisation. This switch topology has the cycloconverter advantage of lacking a DC link, and hence lacks an energy store, while offering a potentially unlimited frequency range.
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Polařský a obvodový model dávkovače zinku
Musil, Ladislav ; Praglowska-Gorczynska, Z.
Electromagnetic feeders of molten metals are used in some industrial technologies, particularly for accurate dosing. Mathematical model of such devices represents a complicated coupled task characterised by interaction of electromagnetic, temperature and flow fields. The paper deals with numerical computation of several important quantities of the device providing its circuit parameters
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Development and Application of Thyristor IGCT
Bureš, J. ; Homola, J. ; Jehlička, Vladimír ; Kalčík, K.
The development of the power switching device IGCT in the Co. Polovodiče, Inc., principle of operation of the device, practical design of an IGCT chopper for feeding a traction motor, the device parameters. The development of an inverter with IGCTs in Institute of Electrical Eng. of Academy of Sciences of the Czech Rep. destined for means of transport driven by an induction motor.
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Leaf-spinning moths (Lepidoptera) feeding on Vaccinium uliginosum L. along an ecological gradient of the Šumava peat bogs
Spitzer, Karel ; Bezděk, Aleš ; Jaroš, Josef
The leaf-spinning moths (Lepidoptera: Tortricidae, Gelechiidae, Chimabachidae and Geometridae) associated with the boreal plant Vaccinium uliginosum L. were investigated in two different peat bogs (Mrtvý Luh near Volary and Chalupská Slať near Borová Lada). During four years (1998-2001) of collecting leaf spinnings, 19 species of moths were recorded from both peat bogs. The occurence of moths was structured along a distinct mesoclimatic gradient. Species closely associated with peat bogs (tyrphobiontic and tyrphophilous taxa) were found to be most abundant in treeless centers of both bogs in comparisonwith marginal parts.
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