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531.
Ph. Rebillard P.N. Pascaud D. Sarrat 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(11):133-138
Synthetic Aperture Radar data were acquired over Tunisia by Seasat in Aug. 1978 and by SIR-A in Nov. 1981. The radar images are contrasted to the Landsat scenes overlapping the same area. The Landsat images were taken in Aug. 1978 and in Sept. 1981. In this study, subareas of the SIR-A and MSS images are registered to the corresponding Seasat data (1313 lines by 1970 samples). The test site is located East of Kairouan, Tunisia. It is a low relief area with subdesertic climatic conditions. This region was selected for it has been surveyed by both Seasat and SIR-A providing perpendicular radar illumination directions. The multispectral and multitemporal coregistered data set enables comparisons between the systems (radar versus MSS, and Seasat versus SIR-A), and change detection in the desertification processes and on the surface of the playas. 相似文献
532.
Ts. Pasheva D. Samardziev N.P. Benkova N.A. Kochenova Ju. Kushnerevskij 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(1):61-64
In this paper, combined bottom- and topside ionospheric N(h)-profiles are presented for the Bulgarian region. The profiles were constructed using ground (ionospheric observatories Sofia and Michurin) and satellite (Interkosmos-19) observations /1/.The observatories make quarter-hourly observations; in order to connect bottom and upper parts of the N(h) profile, we selected satellite orbits passing rather near to the observatory (zenith distance lsss than 100 km). Thus the time difference between ground station and satellite measurement was never more than 7.5 min. 相似文献
533.
N. V. Stoichev S. B. Yaneva L. L. Regel I. V. Videnskiy 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1988,8(12):171-174
Directional solidification of eutectic Al-Cu alloys has been studied to demonstrate the influence of both impurity concentration and convective conditions. The λ/R relations show that higher iron concentration and intensive stirring coarsen the microstructure. The formation and growth of new iron-containing phases at the solidification front restrict impurity influence. Kinetic data follow a dependence λ.Rn=const with n-value close to 0,5. 相似文献
534.
P.N. Bhat S.K. Gupta P.V.Ramana Murthy B.V. Sreekantan S.C. Tonwar P.R. Vishwanath 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
In a further study of sporadic emission from pulsars we find evidence for short lived intense emission from the Crab pulsar. 相似文献
535.
N. Junkes W. Pietsch G. Hensler 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1993,13(12):323-326
We present results from ROSAT observations of NGC 1808 and NGC 2903. Exposures of 10 ksec each with the PSPC detector show X-ray sources at the central positions of both galaxies which are classified as nuclear starburst galaxies. Both targets, NGC 1808 and NGC 2903 appear slightly extended in X-ray maps in the energy band 0.1–2.4 keV. The X-ray spectrum of NGC 1808 shows almost complete absorption below 0.5 keV, indicating an extremely high hydrogen column density towards that source (NH ≈ 8 × 1021cm−2 resulting from model fits on the PSPC spectrum). In case of NGC 2903, the number of counts in the ROSAT band is significantly lower than expected from a previous EINSTEIN investigation of the source. 相似文献
536.
Sanderson R.B. Tsui J.B.Y. Freese N.A. 《IEEE transactions on aerospace and electronic systems》1992,28(4):950-956
A method for digital determination of a single frequency from a sine wave sampled at less than the Nyquist rate is discussed. The method makes use of phase shift information to eliminate the aliasing ambiguity. Multiple sampled data are required to eliminate ambiguity completely. Computer modeling using simulated data corrupted by uncorrelated Gaussian noise was used to verify the approach. The results demonstrate that the frequency of an input sine wave can be correctly identified. This approach can be applied to electronic warfare (EW) receivers to increase their input bandwidth 相似文献
537.
DARN/SuperDARN 总被引:1,自引:0,他引:1
538.
Liquid encapsulation crystal growth from the melt plays an important role in space processing. Use of an encapsulant may avoid evaporation of volatile components and may control thermocapillary flow, which becomes important in microgravity. In the present work the fluid physics of encapsulated liquid gallium is studied analytically and numerically in preparation to forthcoming experiments. It is shown that flow in the viscous encapsulant is essentially negligible and that liquid encapsulation reduces flow velocities in the encapsulated electronic melt. Flow velocity in the gallium is the main parameter in the studies. 相似文献
539.
M. O. Riazantseva O. V. Khabarova G. N. Zastenker J. D. Richardson 《Cosmic Research》2005,43(3):157-164
This work is devoted to studying the sharp boundaries of small-scale structures of the solar wind according to the data of measurements with high time resolution onboard the INTERBALL-1 satellite and simultaneous measurements of the WIND spacecraft. Such issues as the character of change of various plasma and magnetic field parameters on these boundaries, the duration of boundary passage and the balance of the total (thermal plus magnetic) pressure on the boundaries of the structures are considered. On the basis of the vast statistical material available, the typical conditions in the solar wind are investigated, in which such sharp boundaries are observed.__________Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 3, 2005, pp. 163–170.Original Russian Text Copyright © 2005 by Riazantseva, Khabarova, Zastenker, Richardson. 相似文献
540.
M.K. Goel B.C.N. Rao 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(1):111-117
In the present analysis, the mass spectrometer data from the ISS-b satellite, available in the form of contour plots at an average height of 1100 km for every alternate hour, is used. This analysis showed some interesting results in terms of the diurnal variation of the transition heights; at times dominance of He+ over the other ions, and the seasonal variations of different constituents. In the development of ion composition models, it is suggested that this type of result should be taken into consideration. 相似文献