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Differentmodels are proposed for the study ofhybrid systems that are composed of interactingcontinuous and discrete parts as,for instance,inRef.[1 ].Generally,the discrete part is modelledby an automation,and the continuous part by dif-ferent sets of state equations.Jump functions canbe added to represent the discontinuities.But noindication is given about the relations between thedifferent models and the jump functions. This paper isconcerned with the modelling forphysical systems with sw… 相似文献
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Vincent Josselin Pierre Touboul Manuel Rodrigues Françoise Liorzou 《Space Science Reviews》2010,151(1-3):25-38
The MICROSCOPE mission, to be launched in 2011, will perform the test of the universality of free fall (Equivalence Principle) to an accuracy of 10?15. The payload consists of two sensors, each controlling the free fall of a pair of test masses: the first for the test of the Equivalence Principle (titanium/platinum), the second for performance verification (platinum/platinum). The capability to detect a faint violation signal of the EP test is conditioned upon the rejection of disturbances arising from the coupling and misalignments of the instrument vectorial outputs. Therefore the performance of the mission depends on the success of the series of calibration operations which are planned during the satellite life in orbit. These operations involve forced motion of the masses with respect to the satellite. Specific data processing tools and simulations are integral parts of the calibration and performance enhancement process, as are the tests operated on ground at the ZARM drop tower. The presentation will focus on the current status of the MICROSCOPE payload, the rationale for the in-orbit calibrations, the data processing operations and the tests performed at the ZARM drop tower. 相似文献
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Adrienn Luspay-Kuti Olivier Mousis Jonathan I. Lunine Yves Ellinger Françoise Pauzat Ujjwal Raut Alexis Bouquet Kathleen E. Mandt Romain Maggiolo Thomas Ronnet Bastien Brugger Ozge Ozgurel Stephen A. Fuselier 《Space Science Reviews》2018,214(8):115
The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument onboard the Rosetta spacecraft has measured molecular oxygen (O2) in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) in surprisingly high abundances. These measurements mark the first unequivocal detection of O2 in a cometary environment. The large relative abundance of O2 in 67P/C-G despite its high reactivity and low interstellar abundance poses a puzzle for its origin in comet 67P/C-G, and potentially other comets. Since its detection, there have been a number of hypotheses put forward to explain the production and origin of O2 in the comet. These hypotheses cover a wide range of possibilities from various in situ production mechanisms to protosolar nebula and primordial origins. Here, we review the O2 formation mechanisms from the literature, and provide a comprehensive summary of the current state of knowledge of the sources and origin of cometary O2. 相似文献
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Leopold Summerer Jean Pierre Roux Alexey Pustovalov Viacheslav Gusev Nikolai Rybkin 《Acta Astronautica》2011,68(7-8):873-882
This paper presents the results of a study on design considerations for a 100 W radioisotope thermo-electric generator (RTG). Special emphasis has been put on designing a modular, multi-purpose system with high overall TRL levels and making full use of the extensive Russian heritage in the design of radioisotope power systems. The modular approach allowed insight into the scaling of such RTGs covering the electric power range from 50 to 200 We (EoL). The retained concept is based on a modular thermal block structure, a radiative inner-RTG heat transfer and using a two-stage thermo-electric conversion system. 相似文献
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Shock wave/turbulent boundary layer interaction and its control 总被引:3,自引:0,他引:3
The interaction between a shock wave and a boundary layer often leads to extremely detrimental effects, especially if the shock is strong enough to separate the boundary layer. When this happens, there occurs a rapid growth of the dissipative region along with a dramatic intensifying of turbulent fluctuations with the frequent occurrence of buffeting. In the present review some fundamental properties of the interaction are first considered for a two-dimensional, adiabatic flow developing on a flat surface. The following features are first examined: upstream interaction length, incipient shock-induced separation and evolution of the boundary layer properties during the interaction process. Supersonic and transonic flows are both considered. In a second part, the means envisaged to control shock/boundary layer interactions are presented, with emphasis on the physics of phenomena involved in this process. Control methods can be classified into two categories: those acting on the boundary layer properties before it enters the shock region (e.g. wall cooling, wall mass transfer, upstream blowing) and those having a local action in the shock foot region itself (e.g. suction or injection, boundary layer removal, passive control). The most appropriate technique depends on the specific application under consideration. Finally, some calculation methods are briefly presented, most of them being restricted to laminar interactions. 相似文献
28.
Senior political and space agency personnel joined representatives of industry and other space-related institutions for a conference, held in Budapest in January 2009, on how best to structure national and European space governance. Four sessions examined the subject of the conference from a top-down European, a bottom-up national, a theoretical and actor-based and a discursive–participative perspective. The themes and outcomes of the conference are reported below. 相似文献
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Makhosonke Berthwell Dubazane John Bosco Habarulema Jean Claude Uwamahoro 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(1):326-336
For the first time, empirical model of daytime vertical drift based on Empirical Orthogonal functions (EOF) decomposition technique is presented. Day-to-day variability of drift inferred from horizontal (H) geomagnetic field data around dip latitude for the period of 2008–2013 is used to both develop and validate the model. Results show that the EOF technique is promising with modelled values and data giving correlation coefficient values of at least 0.90 for geomagnetic conditions of both and within 2008–2013. Independent model validation shows that in situ values from ion velocity meter (IVM) instrument on-board C/NOFS satellite are closer to model estimates than the climatological Scherliess-Fejer (SF) model incorporated within the International Reference Ionosphere (IRI). 相似文献
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Gerda Horneck Angioletta Coradini Gerhard Haerendel May-Britt Kallenrode Paul Kamoun Jean Pierre Swings Alberto Tobias Jean-Jacques Tortora 《Space Policy》2010
As a result of increasing public and political interest in ‘space’ (i.e. solar system) exploration at the global scale, the Space Advisory Group of the European Commission has evaluated the situation in Europe with regard to its potential to participate in this ambitious global enterprise. Aspects of science, technology, environment and safety, society, spin-offs and international cooperation were all considered. The group concluded that Europe possesses sufficient key technologies and scientific expertise to play a major role in international space exploration and has recommended that the EU take a central role to ensure the success of future European space exploration, not only to give a clear political signal for the way forward but also to ensure an appropriate financial framework. In this way Europe would embrace the spirit of the European Space Policy and contribute to the knowledge-based society by investing significantly in space-based science and technology, thereby playing a strong role in international space exploration. 相似文献