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681.
Corsini G. Gini F. Greco M.V. Verrazzani L. 《IEEE transactions on aerospace and electronic systems》1995,31(3):1202-1204
Maximum Likelihood (ML) algorithms and Cramer-Rao (CR) bounds for the location and scale parameters of the Gumbel distribution are discussed. First we consider the case in which the scale parameter is known, obtaining the estimator of the location parameter by solving the likelihood equation and then evaluating its performance. We next consider the case where both the location parameter and the scale parameter are unknown and need to be estimated simultaneously from the reference samples. For this case, performance is analyzed by means of Monte Carlo simulation and compared with the asymptotic CR bound 相似文献
682.
R. Z. Sagdeev G. A. Avanesov I. V. Barinov A. I. Debabov V. A. Kvasikov V. I. Moroz V. A. Shamis V. I. Tarnapolski D. A. Usikov Ya. L. Ziman B. S. Zhukov B. A. Smith S. Larson F. Szabo K. Szeg A. Kondor L. Vrhalmi E. Mernyi L. Szabo I. Toth P. Cruvellier A. Abergel J. -L. Bertaux J. E. Blamont M. Danz D. Mhlmann H. Stiller H. P. Zapfe 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(12):95-104
The VEGA-1 and VEGA-2 spacecraft made their closest approach to Comet Halley on 6 and 9 March, respectively. In this paper those results of the onboard imaging experiment which were obtained around closest approach are discussed. The nucleus of the comet was clearly identifiable as an irregularly shaped object, with overall dimensions of (16±1)×(8±1)×(8±1) km. The nucleus rotates in the prograde sense about an axis nearly perpendicular to the orbital plane with a period of 53±2 hours. Its albedo is only Many of the jet features observed during the second fly-by have been spatially reconstructed. Their sources form a quasi-linear structure on the surface. The dust above the surface is shown to be generally optically thin with the exception of certain specific dust jets. Brightness features on the surface are clearly seen. Correlating our data with other measurements, we conclude that the dirty snow-ball model will probably need to be revised. 相似文献
683.
L.A. Sromovsky H.E. Revercomb V.E. Suomi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(9):37-40
New Venus temperature profiles, derived from engineering measurements of the Small Probe Net Flux Radiometer (SNFR) instruments generally confirm to high accuracy the vertical structure and horizontal temperature contrast results of Seiff et al. /1/. 相似文献
684.
M. O. Riazantseva O. V. Khabarova G. N. Zastenker J. D. Richardson 《Cosmic Research》2005,43(3):157-164
This work is devoted to studying the sharp boundaries of small-scale structures of the solar wind according to the data of measurements with high time resolution onboard the INTERBALL-1 satellite and simultaneous measurements of the WIND spacecraft. Such issues as the character of change of various plasma and magnetic field parameters on these boundaries, the duration of boundary passage and the balance of the total (thermal plus magnetic) pressure on the boundaries of the structures are considered. On the basis of the vast statistical material available, the typical conditions in the solar wind are investigated, in which such sharp boundaries are observed.__________Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 3, 2005, pp. 163–170.Original Russian Text Copyright © 2005 by Riazantseva, Khabarova, Zastenker, Richardson. 相似文献
685.
M. M. Shvarts S. M. Grach E. N. Sergeev V. L. Frolov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,15(12):59-62
Results of computer simulations of the broad continuum (BC) feature of stimulated electromagnetic emissions (SEE) of the ionosphere are presented. The simulations were performed using the model of BC generation based on the double transformation of electromagnetic waves to upper hybrid (UH) waves and back with artificial small scale irregularities (ASI) of plasma density. An induced scattering of the UH waves by thermal ions provided a wide spectrum of SEE. For the simulations an empirical model of the ASI spectrum, development and decay was used. 相似文献
686.
V.V Benghin V.M Petrov Yu.V Ivanov V.A Shurshakov S.B Kozlova V.D Nguyen J.F Bottollier M Siegrist 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(12):167-170
The estimation of radiation quality factor in space flights is a serious problem of space dosimetry. The solution of this problem is based on LET-spectra measurements. The “NAUSICAA”-device installed on the “MIR” station has a detector with a large geometric factor, that gives the possibility of measuring LET-spectra with sufficient statistic in relatively short time interval and hence the corresponding Q. LET-spectra are accumulated through 24 hour periods and equivalent dose (H), absorbed dose (D), quality factor and flux (F) are measured every 10 minutes. The obtained data permit the estimate of the diurnal Q and Q in South Atlantic Anomaly. These values vary in the range of 1.4 – 2.2. The analysis of these values including their comparison with the calculated results is given in this paper. 相似文献
687.
Microorganisms and enzyme activity in permafrost after removal of long-term cold stress 总被引:1,自引:0,他引:1
E.A Vorobyova V.S Soina A.L Mulukin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(12):103-108
Associations of immobilized microbial cells and organic-mineral complexes containing active enzymes are resistant to long-term (from tens of thousands to millions of years) effects of extremely low temperatures. This association enables the cells to restore their metabolic activity during permafrost thawing, because interactions with the heterogenous medium is made possible by the availability of active immobilized enzymes. The long-term effect of the cold probably favors an adaptational change of microbial metabolism that activates enzymes and cells during thawing. 相似文献
688.
K.Ya. Kondratyev V.V. Kozoderov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(6):105-109
Based on the 1974–78 NOAA data, characteristic features of the variability of the Earth's radiation budget and its components over the area of the Northern Atlantic have been analyzed. Calculations of the mean square deviation for the ERB and its components have let to the conclusions that anomalous regions of maximum variability may be considered as energy-active zones. 相似文献
689.
L J DeLucas C D Smith D C Carter P Twigg X M He R S Snyder P C Weber J V Schloss H M Einspahr L L Clancy A McPherson S Koszelak M M Vandonselaar L Prasad J W Quail L T Delbaere C E Bugg 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(1):393-400
The first microgravity protein crystal growth experiments were performed on Spacelab I by Littke and John. These experiments indicated that the space grown crystals, which were obtained using a liquid-liquid diffusion system, were larger than crystals obtained by the same experimental system on earth. Subsequent experiments were performed by other investigators on a series of space shuttle missions from 1985 through 1990. The results from two of these shuttle flights (STS-26 and STS-29) have been described previously. The results from these missions indicated that the microgravity grown crystals for a number of different proteins were larger, displayed more uniform morphologies, and yielded diffraction data to significantly higher resolutions than the best crystals of these proteins grown on earth. This paper presents the results obtained from shuttle flight STS-32 (flown in January, 1990) and preliminary results from the most recent shuttle flight, STS-31 (flown in April, 1990). 相似文献
690.