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621.
We present long-term (1969–1979) observations of Cygnus X-3, obtained by the Vela 5B satellite. The 3–12 keV light curve has 10 day time resolution. Cyg X-3 is a peculiar high-luminosity X-ray source, radiating from the radio region to hard gamma rays of more than 1016 eV. It has a 4.8 hour period, probably orbital, which is not resolved by our present analysis. Long term periodicities of 17, 20, and 33–34 days have been reported by several authors, and explained as the effects of apsidal motion, precession, or an eccentric orbit. We do not observe the 17 and 33–34 day variations, and set upper limits significantly lower than the reported amplitude of the 33–34 day variation. There is weak evidence for a 20 day flux variation. The light curve shows high and low states which alternate with a characteristic timescale of 1 year. There is no counterpart, at this time resolution, of the giant radio outburst of 1972 September. 相似文献
622.
Temperature cycling for more than 300 cycles and for temperatures down to - 175°C performed on soldered silicon cell assemblies with copper, Kovar, and molybdenum interconnectors showed a wide range in failures depending both upon the materials used and on interconnector thickness and substrate material. The solder fatigue failure rate is strongly dependent on stress level in agreement with analytical predictions. 相似文献
623.
Scharf L.L. Harthill W.P. Moose P.H. 《IEEE transactions on aerospace and electronic systems》1969,(4):672-673
The relative merits of intercept and pure pursuit homing are investigated by comparing the expected flight times to a nonmaneuvering target. The analysis is performed for the initial target heading angle uniformly distributed with arbitrary mean and variance. Two specific examples illustrate that intercept homing holds little statistical advantage over pure pursuit homing except when the speed advantage of the missile is very small. 相似文献
624.
L.A. Fisk M.A. Lee 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(3):93-96
A simple shock model for the acceleration of energetic particles in corotating interaction regions (CIR) in the solar wind is presented. Particles are accelerated at the forward and reverse shocks which bound the CIR by being compressed between the shock fronts and magnetic irregularities upstream from the shocks, or by being compressed between upstream irregularities and those downstream from the shocks. Particles also suffer adiabatic deceleration in the expanding solar wind, an effect not included in previous shock models for acceleration in CIR's. The model is able to account for the observed exponential spectra at earth, the observed behavior of the spectra with radial distance, the observed radial gradients in the intensity, and the observed differences in the intensity and spectra at the forward and reverse shocks. 相似文献
625.
G. M. Malacinski A. W. Neff 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1986,6(12):29-36
Developing systems provide unique opportunities for analyzing the effects of microgravity on animals. Several unusual types of cells as well as various extraordinary cellular behavior patterns characterize the embryos of most animals. Those features have been exploited as test systems for space flight. The data from previous experiments are reviewed, and considerations for the design of future experiments are presented. 相似文献
626.
Richard I. Klein Maxwell T. Sandford II Rodney W. Whitaker 《Space Science Reviews》1980,27(3-4):275-282
Two-dimensional calculations of ionization-shockwave propagation into a curved molecular cloud are presented. Density enhancement occurs due to the combined effects of cloud curvature and radiation flow. The star formation process is expected to be enhanced near the edges of irregularly shaped molecular clouds.Authors listed alphabetically 相似文献
627.
J.M. Dlugach E.G. Yanovitskij 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(8):167-170
This work is devoted to the derivation of the optical properties of the Venus atmosphere from “Venera-10” optical measurements. Within the framework of a two-layer model of Venus atmosphere it is found that in the spectral interval 0.52 – 0.85 μm the optical thickness of the upper cloud layer is ≈ 50 and the optical parameters of the lower layer are similar to the Rayleigh ones. Comparison is made between the measurements of radiation field within the atmosphere and the results of strict calculations. A preliminary conclusion is suggested that there are considerable numbers of aerosol particles with a radius ? 0.03 μm in the lower layer. The results of the upper boundary of the cloud layer is estimated to be ≈ 70 km. 相似文献
628.
M. Gogoshev N. Petkov A. Kuzmin Ts. Gogosheva St. Spassov Iv. Kostadinov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(7):115-120
This paper shows the possibilities of the optical scanning imager for investigation of the structure of the auroral, SAR and tropical arcs and in this way to study the particle precipitation, neutral winds across the magnetic equator, drifts, electric fields and the current systems in the ionosphere. 相似文献
629.
J.M. Russell E.E. Remsberg L.L. Gordley J.C. Gille P.L. Bailey 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(10):169-172
The LIMS experiment was launched on the Nimbus 7 satellite for the purpose of sounding the vertical structure of temperature and key upper atmosphere trace gases on a global scale. The technique of thermal infrared limb sounding was used to obtain measurements of O3, H2O, NO2, and HNO3. LIMS collected data almost continuously from late October to late May over the latitude range from 64°S to 84°N. Two of the gases, NO2 and HNO3, are important elements in the NOx chain of chemical reactions leading to ozone destruction. We will describe results for these gases in terms of zonal mean profiles and latitudinal distributions. The period selected for study is January–May 1979, when a major stratospheric warming occurred. 相似文献
630.
M.B. Vasilyev A.S. Vyshlov M.A. Kolosov A.P. Mesterton N.A. Savich V.A. Samovol L.N. Samoznaev A.I. Sidorenko 《Acta Astronautica》1980,7(3):335-340
The experiment with two-frequency radio occultation measurements of the Venusian nightside ionosphere using the Venera-9 and 10 orbiters is described. The experiment is the first of a kind in which the radio link to one of the spacecraft is used to probe the ionosphere, while the other is measuring the variations in the integral electron number density along the path of radio ray propagation. The experiment has been designed to achieve the maximum possible accuracies in determining the parameters of the probed ionosphere using the bistatic two-frequency radio occultation method. 相似文献