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571.
A. K. Dupree 《Space Science Reviews》1981,29(4):479-487
The feasibility of observation of EUV sources is assessed. Many stars have been detected in the EUV range ( 100–1000); line fluxes from others can be predicted. Selected astrophysical problems are reviewed that can benefit from EUV spectroscopy. Included among them are the physics and dynamics of stellar coronae, confirmation of nuclear surface burning on cataclysmic variables, evolutionary properties of white dwarfs, the helium abundance in the interstellar medium, and spectroscopic signatures of neutrino oscillations.Proceedings of the Conference Solar Physics from Space, held at the Swiss Federal Institute of Technology Zurich (ETHZ), 11–14 November 1980. 相似文献
572.
V.L. Swaminathan D.S. Kamat A.M. Rakshit D.K. Chakraborty T.K. Kurien 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(2):55-58
Geological analysis and evaluation of digitally processed and enhanced LANDSAT MSS data products for three test areas of Singhbhum Shear Zone, India has led to certain significant results regarding optimisation and utility of such techniques for geological studies and obtaining additional/new information regarding lithology and structure. Three band-to-band ratio images are found to give best results. Lithologic formations could be subdivided into a number of units. The Westward and southeastward extension of the shear zone could be delineated thereby indicating scope of mineralisation in these parts. 相似文献
573.
K Baltschukat G Horneck H Bucker R Facius M Schafer 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1986,6(11):109-115
Using spores of two Bacillus subtilis strains differing in repair capacity, we have studied repair and mutation induction in the spores after irradiation with very heavy ions up to uranium with specific particle energies up to 18.6 MeV/u. The results indicate that repair and mutation induction after heavy ion irradiation are closely related to each other and that both phenomena strongly depend on the atomic number and specific energy of the ions. The effects are discussed in comparison with results obtained after X-irradiation. 相似文献
574.
A new derivation of the GYROLITE stability criterion is presented. It is confirmed that, for the satellite to have a stable attitude, the spinning part must have a favorable inertia ratio. 相似文献
575.
A numerical method is described for analyzing the performance of an acoustooptic receiver. The method provides output waveforms, probability density functions for samples of the output, and detection probabilities for output samples. The approach is general in that input pulse envelope shapes, pulse offset frequencies, and output rilter magnitude responses are arbitrary. The basic analysis is also independent of the shape of the optical beam and of the photodiode windows. 相似文献
576.
W. K. H. Schmidt 《Space Science Reviews》1981,30(1-4):615-621
Recently there was a suggestion in the literature to apply the principle of the lobster-eye to X-ray astronomy imaging (J.R.P. Angel, Ap. J. 233, 364, 1979). Our own suggestion for a wide angle X-ray telescope made earlier (W.K.H. Schmidt, Nucl. Instr. Meth.127, 285, 1975) is very similar to the above one. It consists of one or two sets of plane mirrors used in a grazing incidence configuration. The advantages of this type of X-ray optics over other systems for particular astronomical observations will be discussed. 相似文献
577.
578.
This paper presents the pointing vector and angular rate relationshipsfor various optical elements as well as techniques developed forestablishing comprehensive analytical models of precision electroopticalstabilization systems. Since the performance of such systemsmay be critically dependent on the disturbance environment and theintegrity of the associated mechanism, these factors are also examinedin detail. 相似文献
579.
Rajasekaran P.K. Srinath M.D. 《IEEE transactions on aerospace and electronic systems》1969,(6):984-988
The problem of minimum time frequency transitions in phase-locked loops with both phase and frequency controls applied is investigated using Pontryagin's maximum principle. Typically, a type II secondorder loop with a damping ratio of 0.707 subjected to a step change in the frequency of its input signal is considered and switchless control strategies that force the transients in the loop to settle down in minimum time are obtained. 相似文献
580.
This paper is concerned with a high-performance nutation damper for use in dual-spin spacecraft. The damper described here makes use of a wheel of uniform mass distribution. The wheel experiences torques which are produced by inertial forces. Damping and restoring (spring) torques are provided by means of a torsional arrangement built around the center of the wheel. The performance characteristics of the above nutation damper are evaluated by considering the small astronomy satellite (SAS-A) spacecraft parameters, and the results for an optimum design of the damper are presented. Finally, the result for the optimum performance is checked with the help of an approximate analysis. 相似文献