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871.
872.
S. A. Mikhailov A. M. Girfanov A. B. Bochkareva A. S. Fal’ko 《Russian Aeronautics (Iz VUZ)》2007,50(4):362-367
The results of numerical and experimental study of physico-mechanical properties of composite materials are proposed and variations in rigidity characteristics of the hub working part of the hingeless type within the entire range of helicopter operational temperatures are evaluated. 相似文献
873.
C. de Jager A. Ollongren Tj. de Graaf B. J. Levin M. Tucker 《Space Science Reviews》1969,9(5):740-742
874.
875.
ARTEMIS Mission Design 总被引:2,自引:0,他引:2
Theodore H. Sweetser Stephen B. Broschart Vassilis Angelopoulos Gregory J. Whiffen David C. Folta Min-Kun Chung Sara J. Hatch Mark A. Woodard 《Space Science Reviews》2011,165(1-4):27-57
The ARTEMIS mission takes two of the five THEMIS spacecraft beyond their prime mission objectives and reuses them to study the Moon and the lunar space environment. Although the spacecraft and fuel resources were tailored to space observations from Earth orbit, sufficient fuel margins, spacecraft capability, and operational flexibility were present that with a circuitous, ballistic, constrained-thrust trajectory, new scientific information could be gleaned from the instruments near the Moon and in lunar orbit. We discuss the challenges of ARTEMIS trajectory design and describe its current implementation to address both heliophysics and planetary science objectives. In particular, we explain the challenges imposed by the constraints of the orbiting hardware and describe the trajectory solutions found in prolonged ballistic flight paths that include multiple lunar approaches, lunar flybys, low-energy trajectory segments, lunar Lissajous orbits, and low-lunar-periapse orbits. We conclude with a discussion of the risks that we took to enable the development and implementation of ARTEMIS. 相似文献
876.
An automatic data processing system for the evaluation of statistically occurring Doppler-difference bursts is described. In addition to the higher accuracy compared with the data acquisition procedures known so far, this technique allows the Doppler-difference method to be used as an operational instrument for investigations into turbulent flows, especially in the case of low particle density and extremely small turbulence degrees. 相似文献
877.
Harriger Keith A. Fay Joseph G. 《IEEE transactions on aerospace and electronic systems》1968,(4):607-612
The first application of a magnetic encoder in a space-to-space command link was proven successful in the Gemini rendezvous missions. The functional aspects of the command link and the mechanization of the encoder are described. 相似文献
878.
E. A. Botan 《Space Science Reviews》1964,3(5-6):715-723
879.
Yu. A. Kovalev V. I. Vasil’kov M. V. Popov V. A. Soglasnov P. A. Voitsik M. M. Lisakov A. M. Kut’kin N. Ya. Nikolaev N. A. Nizhel’skii G. V. Zhekanis P. G. Tsybulev 《Cosmic Research》2014,52(5):393-402
The results of a large number of the antenna radiometric measurements at bands of 92, 18, 6.2, 1.35, and 1.7-1.2 cm are presented by the data of the standard telemetry system of the Spektr-R spacecraft. Both special sessions of calibration object observations in the mode of a single space radio telescope (SRT) operation and numerous observations of researched sources in the mode of the ground-space interferometer were used. The obtained results agree with the first results of Kardashev et al. (2013), i.e., within 10–15% at bands of 92, 18, and 6.2 cm and 20–25% at the band of 1.35 cm. In the main, the measurements for the eight subbands at wavelengths of 1.7-1.2 cm indicate a monotonic increase in the spectral system equivalent flux density (SEFD) of noise radiation with a frequency consistent with the calculated estimates for the discussed model. The sensitivity of the ground-space interferometer for the five subbands at wavelengths from 1.35 to 1.7 cm can be higher by a factor of 1.5, and for the three subbands from 1.35 to 1.2 cm lower by a factor of 1.5 than at the band of 1.35 cm. The SRT contribution to the interferometer sensitivity proportional to the square root of SEFD is close to the design one at the bands of 92 and 18 cm and decreases the design sensitivity approximately by a factor of 1.5 and 2 at the bands of 6.2 and 1.35 cm, respectively. These differences of implemented values from the design ones were not significantly affected the scientific program implementation. 相似文献
880.
A.T.Y. Lui 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2000,25(12):2389-2394
Substorm evolution of the near-Earth (|X|<15 RE) plasma sheet has been emphasized recently because the inner tail is thought to link closely to the substorm auroral activity in the ionosphere during the early stage of substorms. In this paper, we discuss how the inner tail substorm phenomena during the late substorm growth phase and early expansion phase are accounted for by the two prevailing substorm models, namely, the near-Earth neutral line model and the current disruption model. We find that the late growth phase features are more satisfactorily accounted for by the current disruption model than by the near-Earth neutral line model. In addition, detailed observations on current disruption show evidence inconsistent with the proposed idea of dipolarization being due to plasma flow braking from reconnection in the mid-tail region, which poses a difficulty to the near-Earth neutral line model as well. 相似文献