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891.
It is shown how a uniform linear array of crossed dipoles may be used with the ESPRIT algorithm and spatial smoothing techniques to estimate the arrival directions and polarizations of incoming coherent plane waves. Some examples showing typical performance are presented. One method of smoothing can be used where it is necessary to estimate both the arrival angles and polarizations of signals. Two other methods can be used when only the arrival angles are of interest 相似文献
892.
A brief review of publications on the problem of two fixed centers is given, including its generalizations and astronomical applications. A comparison of the Darboux potential with that of Eve Gredeaks is made. An account of the basic points of development of modern high-precision theories of the motion of planetary satellites, based on the Gredeaks’ intermediate orbit, is given.__________Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 3, 2005, pp. 194–200.Original Russian Text Copyright © 2005 by Lukyanov, Emeljanov, Shirmin.Dedicated to the memory of Professor Evgenii Petrovich Aksenov 相似文献
893.
I V Getselev P P Ignatiev N A Kabashova N N Kontor A R Moszhukhina G A Timofeev T G Khotilovskaya 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(2-3):441-444
Based on the available measurement data, simulations of radiation conditions during spacecraft flights in the interplanetary space and in the Earth's and Jupiter's radiation belts has been carried out. The > or = 10 MeV and > or = 30 MeV solar flare proton fluence forecast has been proposed for Cycle 22. Radiation conditions due to both magnetospheric electrons and protons and to solar flare protons, magnetic rigidity cutoff being taken into account, have been evaluated on spacecraft trajectories in the Earth's and Jupiter's magnetospheres. 相似文献
894.
895.
A generalized small-signal analysis approach that is based on both the Taylor's series expansion and the state-plane diagram is presented. A generalized discrete small-signal model for a double-ended DC-to-DC resonant converter operating in the continuous conduction mode is also given. Based on the model derived, the frequency responses for two transfer functions, namely, the line-to-output and the control-to-output transfer functions, are obtained. The technique is verified by applying it to the conventional series resonant converter whose small-signal analysis is known 相似文献
896.
Automatic target recognition (ATR) is an important capability for defense applications. Many aspects of image understanding (IU) research are traditionally used to solve ATR problems. The authors discuss ATR applications and problems in developing real-world ATR systems and present the status of technology for these systems. They identify several IU problems that need to be resolved in order to enhance the effectiveness of ATR-based weapon systems. They conclude that technological gains in developing robust ATR systems will lead to significant advances in many other areas of applications of image understanding 相似文献
897.
T.G. Adeishvili T.I. Gagua G.G. Managadze 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(4):251-254
This paper discusses photometric measurements made of the ionospheric excitation of the line at the time of electron beam injection from a rocket into the Earth's ionosphere. The gradual increase of the glow intensity per impulse occurs due to accumulation of the energy of excited states of N2(A3Σ+u) and O(′S) during their lifetimes. The large disturbed zone in the near-rocket environment (size >500 m) is connected via the interaction of ions accelerated in the rocket potential field with ionospheric components. The glow intensity modulation is observed at a height of ~98 km during the electron beam injection simultaneously with the ignition of the beam-plasma discharge (BPD). The intensity minima are explained by a decrease of the energy of accelerated ions due to effective neutralization of the rocket body by the BPD plasma. The height profile of the glow intensity revealed two maxima at heights of ~103 km and ~115 km. The second maximum (at ~115 km) indicates that, at these heights, both collision and collision-free mechanisms of accelerated ion energy transport to ionospheric components exist. 相似文献
898.
The pioneer venus orbiter ultraviolet spectrometer experiment: Analysis of hydrogen lyman alpha data
L.J. Paxton D.E. Anderson A.I.F. Stewart 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(9):129-132
Pioneer Venus Orbiter Ultraviolet Spectrometer (PVOUVS) HI 1216Å data from six (6) orbits are analyzed. Analysis of subsolar region periapsis data show that for an exobase temperature of 305K, the exobase density is and the column abundance of atomic hydrogen between 110 and 200 km is 2.4 ± 0.8(13) cm?2. The upward flux through the exobase is determined to be 7.5 ± 2.5(7)/cm2s. Apoapsis data were analyzed for both evening and morning geometries. We conclude: (1) the observed limb profiles show a diurnal variation consistent with Brinton et al.; (2) the model temperature field provides a good fit to the morning data, but the morning temperature field must be used to match the evening data; and (3) the theoretical Ly α limb intensity profiles are sensitive to small changes in the shape and magnitude of the variation of exobase hydrogen with solar zenith angle. The solar Ly α flux at line center required to fit the magnitude of the data is 8(11) photons/cm2s Å at Venus. 相似文献
899.
E.S. Kazimirovsky E.I. Zhovty 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(1):149-151
Methods for constructing a dynamical part of the IRI model are described. 相似文献
900.
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