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941.
942.
D. Spänkuch 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(5):1-2
Based on the findings of the meeting of JSC experts on “Aerosol and Climate” (Geneva, 27–31 October 1980) the general research strategy consisting of three phases will be presented. The three phases are: Phase I: Sensitivity tests with available models Phase II: Improvement of climate models and data bases Phase III: Development of advanced climate models with internal aerosol generation and regulation processes. COSPAR's role within this research strategy is outlined. 相似文献
943.
Attitude and Oribit Estimation Using Stars and Landmarks 总被引:2,自引:0,他引:2
White R.L. Adams M.B. Geisler E.G. Grant F.D. 《IEEE transactions on aerospace and electronic systems》1975,(2):195-203
An extended Kalman filter is used to process line-of-sight measurements to stars and known landmarks providing a statistical indication of performance in estimating spacecraft attitude, orbital ephemeris, and the bias drift of a set of three strapdown gyros. The landmark measurements were assumed to have been taken from the imagery of an Earth-observing multispectral scanner. It is shown that filtering of these noisy measurements results in highly accurate estimates of the above parameters. Results are given showing the sensitivity of performance to various system parameters such as star tracker accuracy, errors in the knowledge of landmark position, and number of stars and landmarks processed. 相似文献
944.
The structural features of the germanium-silicon solid solution crystals obtained under microgravity
V.S. Zemskov I.N. Belokurova I.L. Shulpina A.N. Titkov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(5):11-14
Structural features of germanium-silicon solid solution crystals have been investigated and silicon distribution in the crystals has been studied. All the crystals obtained under microgravity had, in spite of good external shape and facetting, a poorer internal structure than those obtained on Earth. The distribution of silicon have been shown to be non-uniform. High dislocation densities were observed. 相似文献
945.
The application of Fourier Transform Spectroscopy (FTS) to planetary research is reviewed. The survey includes FTS observations of the Sun, all the planets except Uranus and Pluto, the Galilean satellites and Saturn's rings. Instrumentation and scientific results are considered. The prospects and limitations of FTS for planetary research in the forthcoming years are discussed. 相似文献
946.
Chetty P.R.K. Polivka W.M. Middlebrook R.D. 《IEEE transactions on aerospace and electronic systems》1980,(2):191-201
A new approach to the design of power systems is presented in which a microprocessor is used as a controller for a digital shunt regulator (DSR). This approach meets the demands of future space and ground missions, i. e., high efficiency, high reliability, low weight, low volume, increased flexibility, and less development time. This approach responds to future demands by permitting realtime modification of system parameters for system optimization. This feature is especially important in the event of an anomaly. As the microprocessor need not be dedicated to the DSR, it can simultaneously be used for battery management and for charge regulator/discharge regulator control. This approach also reduces the component count, simplifies assembly and testing of the unit, results in significant time saving, and increases the reliability. 相似文献
947.
A survey is presented of the potential benefits, possible pitfalls, and anticipated testing needs of integrating inertial guidance systems with systems dependent on the availability of the electromagnetic spectrum. Commonly referred to as integrated communications, navigation, and identification avionics (ICNIA), these systems of the future offer the combined potential for superb positioning and secure communications. The general characteristics (if current development trends continue) of the next-generation inertial navigation systems (INS) are briefly presented, followed by key modular and conceptual issues in the synthesis of this INS with systems dependent on the EM spectrum. Modular issues as considered here are those related to detailed implementation and resulting efficiency. Conceptual issues are those related to overall military strategy and resulting effectiveness. An example of modular systems integration is given, and a few preparations which can be anticipated for the field testing of integrated systems are presented, followed by concluding comments 相似文献
948.
D.A. Usher M.C. Needels 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(12):163-166
Aminoacylation of the “internal” 2′-hydroxyl groups of poly(A) with the imidazolide of racemic DL-leucine resulted in the formation of an enantiomeric excess of the D-ester, whereas aminoacylation with the imidazolide of racemic N-3,5-dinitrobenzoyl-DL-leucine gave an enantiomeric excess of the L-ester. Comparison of these results with those obtained earlier for alanine shows that the larger side chain tends to favor the formation of the D-ester. High resolution proton magnetic resonance spectroscopy was performed on the D- and L-alanyl “internal” 2′-esters of 3′,5′-ApA. The resonance of the side chain methyl group of the D-ester is upfield from that of the L-ester, and the separation of the peaks increases with a decrease in temperature. 相似文献
949.
We consider a nonstationary nonlinear integrodifferential equation describing the evolution of a disturbed plane flame front. The following two-dimensional problems are solved numerically: (i) The formation of a wrinkled noncellular laminar flame front under conditions of spontaneous hydrodynamic instability. (ii) The formation of a turbulent cellular flame front under conditions of spontaneous diffusional-thermal instability. (iii) The formation of a turbulent wrinkled-cellular flame front under conditions of spontaneous hydrodynamic and diffusional-thermal instability. We compute the flame front velocity in laminar and turbulent propagation. 相似文献
950.
Kim N.P. Stanbery B.J. Burgess R.M. Mickelsen R.A. McClelland R.W. King B.D. Gale R.P. 《Aerospace and Electronic Systems Magazine, IEEE》1989,4(11):23-32
Mechanically stacked tandem cells consisting of GaAs thin-film upper cells and CuInSe2 thin-film lower cells have been developed to meet the increasing power needs projected for future spacecraft. The authors report the fabrication of the first highly efficient lightweight GaAs/CuInSe2 tandem cell on a 2-mil thick substrate, update recent performance improvements in thin-film GaAs/CuInSe2 tandem cells, and discuss their application to space power systems. The efficiency of 4-cm2 cells has improved to 21.6% AM0, the highest ever reported for a thin-film photovoltaic cell. Lightweight 4-cm2 tandem cells have been successfully fabricated with efficiencies as high as 20.8%. These cells weighed about 180 mg without optimized substrate trimming. Radiation and operating temperature effects on GaAs/CuInSe2 tandem cells are also discussed, and an interconnect scheme to form a voltage-matched string is described 相似文献