|
| |
|
| |
|
| |
|
|
Členství žen v předních vědeckých společnostech ve 20. století [v českých zemích]
Barvíková, Hana ; Martinovský, Martin
During the whole 20th century there were 5 or 6 central scholar institutions in the Czech lands. Their members were elected, and the membership represented the highest acknowledgment of research abilities and importance of the person for her/his discipline. Women were, however, elected only very rarely; only four local scholars (and two foreign) became members in the first half of the century, followed by eleven ones in the second part. The article maps possibilities and conditions of the elections influenced obviously above all by the very beginnings of women scholars, pioneers in the world of science and humanities in the first fifty years, by the totalitarian regime and by the existence of the unique, really centralized institution from 1950s. Small portraits of all women and circumstances of their elections together with the description of the situation regarding women in research in the end of the 20th and in beginning of the 21th century are included.
|
|
| |
|
|
Some Aspects of Matrix Converter System Realization
Lettl, Jiří ; Flígl, S.
Matrix converters, initially called direct frequency changers in general only, have attracted an amount of interest over the past twenty-five years already, but with the rapid progress in the semiconductor devices and control circuits they find once again new utilisation. The presented paper deals with the recent concept of hybrid and power splitting traction drive systems.
|
|
| |
|
|
Control Strategy of Parallel Hybrid Filter for Harmonic Mitigation
Škramlík, Jiří ; Valouch, Viktor
The strategy features a small sensitivity against a disturbed supply voltage system and enables us to set grid phase currents in the phase with respective voltages. The expected properties of the PHF control system have been confirmed by experimental tests in the laboratory. The data show that the modified control strategy yields better results than those obtained by using control systems reported previously, especially in case of an unsymmetrical and non-sinusoidal voltage system and the demand of zero reactive power withdrawn from the grid.
|
|
| |
|
|
The natural fish reproduction of lowland stretches of Morava and Dyje rivers
Valová, Z. ; Jurajda, Pavel
Lowland rivers decreased their habitat diversity and get an uniform character due to their regulation and channelisation. This modifications affected the natural fish reproduction. The efficiency of natural fish reproduction was studied using Point Abundance Sampling strategy by electrofishing in three differently modified stretches of two adjacent lowland rivers in the late summer of 1999-2003.
|
guest ::
