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221.
B. de Montluc 《Space Policy》1996,12(4):245-264
A new world order has begun to appear since the early 1990s. The simplicity of interaction between individual states, based on the rivalry between the two superpowers, is gradually being replaced by new attitudes formed in a complex, uncertain and risky context. States still have a role, discussing, negotiating, legislating, creating infrastructures and issuing directives. However, political power, with its laws, its order and its reasoning, is being supplemented and often dominated by other forms of power: economic, financial or influence. Space policies follow or sometimes precede political trends. They were the spearhead of the ‘glory years’ and still bear the imprint of the simple rules which applied twenty years ago. However, amid the current uncertainty, it is possible to perceive the outline of the space policies of the future, which may contribute to the definition of new watersheds in the modern world. 相似文献
222.
223.
Sanderson A.C. Peshkin M.A. Homen de Mello L.S. 《IEEE transactions on aerospace and electronic systems》1988,24(5):619-629
Space-based robotic systems will require novel technologies of planning and manipulation to accomplish complex tasks such as diagnosis, repair, and assembly task representation, discrete task planning, and control synthesis which provide a design environment for assembly systems, and which extend to planning of manipulation operations in unstructured environments. In this approach, assembly planning is carried out using the AND/OR graph representation which encompasses all possible partial orders of operations and may be used to plan assembly sequences. A novel algorithm for planning disassembly and repair using the AND/OR graph is introduced, and examples of repair sequences generated for a satellite electrical module are described. For discrete task planning, the configuration map facilitates search over discrete parameters in the space of bounded configuration sets 相似文献
224.
R Marco J González-Jurado M Calleja R Garesse M Maroto E Ramírez M C Holgado E de Juan J Miquel 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(1):157-166
The results are presented of the exposure of Drosophila melanogaster to microgravity conditions during a 15-day biosatellite flight, Biokosmos 9, in a joint ESA-URSS project. The experimental containers were loaded before launch with a set of Drosophila melanogaster Oregon R larvae so that imagoes were due to emerge half-way through the flight. A large number of normally developed larvae were recovered from the space-flown containers. These larvae were able to develop into normal adults confirming earlier results that Drosophila melanogaster of a wild-type constitution can develop normally in the absence of gravity. However, microgravity exposure clearly enhances the number of growing embryos laid by the flies and possibly slows down the developmental pace of the microgravity-exposed animals. Due to some problems in the experimental set-up, this slowing down needs to be verified in future experiments. No live adult that had been exposed to microgravity was recovered from the experiment, so that no life span studies could be carried out, but adult males emerged from the recovered embyros showed a slight shortening in life span and a lower performance in other experimental tests of aging. This agrees with the results of previous experiments performed by our groups. 相似文献
225.
Low-thrust transfers between preset orbits are considered in the presence of perturbations of different origin. A simple method of finding the transfer trajectory is suggested, based on linearization of motion near reference orbits. The required accuracy of calculations is achieved by way of increasing the number of reference orbits. The method can also be used in the case of a large number of revolutions around the attracting center: no averaging of motion is required in this case. The suggested method is applicable as well, when the final orbit is specified partially and when there are constraints on the thrust direction. The optimal solution to the linearized problem is not optimal for the original problem; closeness of solutions to these two problems is estimated using a numerical example. Capabilities of the method are also illustrated by examples. 相似文献
226.
The RUSI ‘Space and UK National Security’ conference was held in London on 2 October 2012 and, with the ‘Cyber Alliances: Strategy Partnerships in Cyber Space’ conference’ of 14–15 November 2012, brought together space and cyberspace specialists from more than 15 countries, across four continents. Alixe Buckerfield de la Roche reports on key points discussed across both conferences: (1) space as a shared domain, and building resilience; (2) governance; (3) national responses to space security; (4) partnerships and alliances, space situational awareness, space debris, and new initiatives; (5) the space–cyberspace merger; and (6) commercial and military sectors. Consensus on critical areas for further action emerged, and for that reason the conjunction of the two conferences was significant. 相似文献
227.
P.A.J. de Korte J.J. Claas F.A. Jansen S.P. McKechnie 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(3):57-59
The EXOSAT observatory has detected the nucleus of NGC 1360 in four photometric energy bands. The data rules out that the emission is from blackbody origin. Initial fits made with LTE model atmosphere spectra require the presence of highly ionized Oxygen and Neon in the stellar atmosphere. 相似文献
228.
Bertrand de Montluc 《Space Policy》1997,13(1):9-14
The current international economic and technical climate has caused changes in the European space sector such that Italy is now struggling to maintain third place in the European hierarchy, the Franco-German relationship has become less dominant, while the UK is becoming more open towards European cooperation. This article analyses the current policies of Germany, the UK and Italy and examines their operating methods. The author speculates on the outlook for these countries in the next 10 years: neither the UK, nor Italy looks set to become a major player and German policy will depend on the success of its upcoming strategic plan. All these countries, and France, however, will need to engage in intensive bilateral consultations if they wish to compete in worldwide markets. 相似文献
229.
I.S. Batista J.R. de Souza M.A. Abdu E.R. de Paula 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(12):87-90
We used total electron content (TEC) data measured by Faraday rotation technique over Cachoeira Paulista (22.5°S, 45°W), in Brazil, to study the TEC variations with the solar flux at 10.7 cm (F10.7) and to compare the results with the IRI90 predictions. The data were divided into summer, equinox and winter. During the analysed period F10.7 varied from 66 up to 330. Our data shows that the observed TEC at 1600 LT (around the diurnal maximum) and at 0500 LT (around the diurnal minimum) increases with F10.7 until saturation is reached which occurs at F10.7≈210 to 220 for equinox and summer, and at F10.7≈180 for winter months. Comparison with the IRI90 predictions shows that IRI overestimates the TEC at 0500 LT for all solar flux values. At 1600 LT, IRI overestimates the observed TEC for low solar flux but underestimates it for high solar flux values. 相似文献
230.
Miroslav Plavec R. Hoekstra C. De Jager Ji⋖´ Grygar J. Otterman H. M. van den Dool O. Namba C. J. Th. Gunsing Jean-Claude Pecker K. K. Kwee L. Perek D. Callebaut Jan Kuijpers W. de Graaff G. C. M. Reijnen B. Swanenburg N. Grevesse J. Kleczek P. P≙quet A. D. Fokker H. G. van Bueren D. Edgar Page R. J. van Duinen Franco Pacini 《Space Science Reviews》1978,21(4):469-483