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991.
Übersicht Die zusätzlichen Stromwärmeverluste im Läufer ändern sich bei einem Drehzahlstellantrieb je nach Betriebsweise des Umrichters beträchtlich. Im Blockbetrieb ist der Gesamtverlust kaum vom Lastzustand (Schlupf) abhängig. Im Synchronismus sind die Verluste jedoch ungleichmäßig auf die einzelnen Läuferstränge oder Stäbe verteilt. Die Maxima und Minima der Stabverluste stehen im Synchronismus etwa im Verhältnis 10:1 zueinander. Die Verluste in dem am stärksten beaufschlagten Läuferstab liegen nicht wesentlich niedriger als im Bemessungsbetrieb. Die gesamten zusätzlichen Stromwärmeverluste wachsen bei konstanter Speisefrequenz quadratisch mit der Spannung. Im Feldschwächbereich nehmen sie in Abhängigkeit von der Speisefrequenz ungefähr nach der Funktion 1/1,52 ab.
Additional rotor I2R-losses and their spatial distribution in three-phase windings respectively rotor bars of induction motors fed from six-step U-invertors
Contents Additional rotor I2R-losses in speed variable drives with induction motors change very strongly with the operation mode of the invertor. During block-operation the sum of these additional losses is nearly independent of the load (slip). But at synchronous speed the losses are distributed very unequally among the phase windings respectively the rotor bars. The ratio of maximum to minimum bar losses is approximately 10:1. The highest ohmic loss in a bar is nearly the same as the rated bar loss. The additional rotor I2R-losses change with the square of the voltage. In the field weakening range the losses drop with the frequency approximately following the function 1/1,52.相似文献
992.
We have shown that dicyanogold(I), [Au(CN)(2)](-) is a common metabolite found in blood and urine samples of patients treated with different gold based drugs. Some patients have high levels of gold within their red blood cells (RBCs). Size exclusion and C18 reversed phase chromatography show that the majority of the gold in RBC lysates is bound to protein, but small molecules such as dicyanogold(I) and gold-glutathione complexes are also present. Dicyanogold incubation with red blood cells in vitro leads to a rapid and complete uptake of gold. This uptake is unaffected by DIDS, an inhibitor of the anion channel, but is blocked by the addition of external cyanide. Dicyanogold is also readily taken up by H9 cells, a continuous CD(4+) cell line. This uptake is significantly inhibited by N-ethylmaleimide, suggesting a requirement for sulfhydryl groups. Dicyanogold inhibits the replication of the AIDS virus, HIV, in a cell culture model. 相似文献
993.
994.
995.
A real-time polychromatic target-detection technique that uses a computer-addressable color liquid-crystal- TV-based joint-transform correlator (JTC) is presented. One of the major features of the polychromatic JTC is that the spectra content of the object can be exploited. Since the liquid-crystal-TV panel is computer addressable, the JTC system can be made adaptive, by which the joint-transform power spectrum can be manipulated. Experimental demonstration of the proposed polychromatic JTC is provided, in which we show that the spatial and the spectral content of targets can be detected. 相似文献
996.
The analysis of statistical parameters of computer-generated therfial images by a line-scanning technique indicates an approach to efficient image transmission. 相似文献
997.
The inverse WKB (IWKB) approximation has been extended to derive the index distribution functions from the measured mode indices of a planar waveguide. Through the use of this technique, the forms of the index distribution functions are obtained by IWKB approximation and a criterion is used to derive the functions accurately. The results are compared to the exponential and Fermi distributions. It is shown that the index profile, surface index, and waveguide depth can be obtained more accurately than with the original IWKB approximation. Finally, the index distribution function of a c-cut proton-exchanged LiTaO(3) waveguide is given by this technique, the mode indices calculated with this function agree with the experimental results in the range of 10(-4). 相似文献
998.
The structural properties of the solid phase, formed by the hydrolysis of Fe3+ ions in Fe2(SO4)3 solutions at 90 or 120 °C, were investigated using X-ray diffraction,57Fe Mössbauer spectroscopy, Fourier transform-infrared spectroscopy (FT—IR) and transmission electron microscopy. The concentration regions of Fe2(SO4)3 were determined for the precipitation of goethite, -FeOOH, or hydronium jarosite, H3OFe3(OH)6(SO4)2 as a single phase. Superparamagnetic behaviour of -FeOOH particles was observed. Hydrolysis of Fe3+ ions in 0.1 M Fe2(SO4)3 solutions at 120 °C produced H3OFe3(OH)6(SO4)2 and basic sulphate, Fe4(OH)10SO4. The interpretation of57Fe Mössbauer and FT—IR spectra is given. 相似文献
999.
Investigation of the characteristics of thermionic converters with a Mo (110) single-crystal collector with Ion-implanted oxygen 总被引:1,自引:0,他引:1
S. S. Gerashchenko M. I. Guseva V. A. Koryukin V. Z. Kaibyshev V. P. Obrezumov Yu. V. Taldonov 《Atomic Energy》1994,76(2):147-149
Institute of Nuclear Reactors, Russian Scientific Center "Kurchatovskii Institut." Translated from Atomnaya énergiya, Vol.
76, No. 2, pp. 151–152, February, 1994. 相似文献
1000.