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991.
F.L. Scarf D.A. Gurnett W.S. Kurth R.L. Poynter 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(12):253-258
At Uranus, the Voyager 2 plasma wave investigation observed very significant phenomena related to radio emissions, dust impacts and magnetospheric wave-particle interactions. On January 19, 1986 (R= 270RU) the plasma wave investigation detected an intense radio burst at 31 and 56 kHz, and this provided the first indication that Uranus had a magnetosphere. During the encounter we observed more of these sporadic bursts, along with relatively continuous radio emissions extending down to 10 kHz, and a sporadic narrowband radio signal with f near 5 kHz. As Voyager passed through the ring plane, the plasma wave investigation recorded a large number of dust impacts. The dust ring was relatively diffuse (thickness of several thousand kilometers) and the peak impact rate was near 50 hits/second. The Voyager 2 plasma wave instrument also detected many strong electromagnetic and electrostatic plasma waves, with intensity peaks in the region within 12 Uranus adii. These waves have characteristics that can interact strongly with the local plasma and with the trapped energetic particles, leading to precipitation into the atmosphere, charged particle acceleration, and charged particle diffusion. In addition we detected strong wave activity in the region of the bow shock and moderate levels in the magnetic tail. 相似文献
992.
993.
The problem of stabilizing a tumbling satellite prior to attitude control is discussed. The method of Hamilton-Jacobi theory is used to derive an explicit closed-loop control law for the problem. 相似文献
994.
995.
We present a brief overview of the probable velocity-shear induced phenomena in solar plasma flows. Shear-driven MHD wave oscillations may be the needed mechanism for the generation of solar Alfvén waves, for the transmission of fast waves through the transition region, and for the acceleration of the solar wind. This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
996.
997.
Space Science Reviews - 相似文献
998.
999.
Ferrando C. Perez A. Sanchez Pena R.S. 《IEEE transactions on aerospace and electronic systems》1999,35(4):1219-1229
A procedure to compute the integer ambiguity problem when a GPS receiver is used in a multiple antenna configuration attached to a rotating spacecraft is presented. The method is applied to a simulation of an experimental satellite which uses the GPS receiver for attitude determination 相似文献
1000.
Bandwidth maximization for satellite laser communication 总被引:3,自引:0,他引:3
Arnon S. Rotman S.R. Kopeika N.S. 《IEEE transactions on aerospace and electronic systems》1999,35(2):675-682
Free space optical communication between satellites networked together can make possible high speed communication between different places on Earth. The basic free space optical communication network includes at least two satellites. In order to communicate between them, the transmitter satellite must track the beacon of the receiver satellite and point the information optical beam in its direction. The pointing systems for laser satellite communication suffer during tracking from vibration due to electronic noise, background radiation from interstellar objects such as Sun, Moon, Earth, and Stars in the tracking field of view, and mechanical impact from satellite internal and external sources. Due to vibrations the receiver receives less power. This effect limits the system bandwidth for given bit error rate (BER). In this research we derive an algorithm to maximize the communication system bandwidth using the transmitter telescope gain as a free variable based on the vibration statistics model and the system parameters. Our model makes it possible to adapt the bandwidth and transmitter gain to change of vibration amplitude. We also present an example of a practical satellite network which includes a direct detection receiver with an optical amplifier. A bandwidth improvement of three orders of magnitude is achieved in this example for certain conditions, as compared with an unoptimized system 相似文献