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41.
Chiara Toglia Marco Sabatini Paolo Gasbarri Giovanni B. Palmerini 《Acta Astronautica》2011,68(7-8):1031-1041
Space graspers are complex systems, composed by robotic arms placed on an orbiting platform. In order to fulfil the manoeuvres’ requirements, it is necessary to properly model all the forces acting on the space robot. A fully nonlinear model is used to describe the dynamics, based on a multibody approach. The model includes the orbital motion, the gravity gradient, the aerodynamic effects, as well as the flexibility of the links. The present paper aims to design, thanks to nonlinear optimization algorithms, a class of manoeuvres that, given the same target to be grasped, are characterized by different mission objectives. The grasping mission can be performed with the objective to minimize the power consumption. Collision avoidance constraints can be also added when the target is equipped with solar panels or other appendices. In some cases, large elastic displacements should be expected, possibly leading to an inaccurate positioning of the end-effector. Therefore, different design strategies can require that the manoeuvre is accomplished with minimum vibrations’ amplitude at the end-effector. Performance of the different strategies is analyzed in terms of control effort, trajectory errors, and flexible response of the manipulator. 相似文献
42.
Maria Daniela Graziano Marco D’Errico Elena Razzano 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
A future system integrating data from remote sensing and upcoming AIS satellites is analyzed through the development of a novel design method for global, discontinuous coverage constellations. It is shown that 8 AIS satellites suffice to guarantee global coverage and a ship location update of 50 min if the spaceborne AIS receiver has a swath of 2800 nm. Furthermore, synergic utilization of COSMO/SkyMed and Radarsat-C data would provide a mean revisit time of 7 h, with AIS information available within 25 min from SAR data acquisition. 相似文献
43.
C. De Jager 《Space Science Reviews》1993,66(1-4):7-19
The paper gives a summary of the situation mid-1993 of theory and observations regarding massive stars. I describe: stellar mass loss and its implications, pre-main-sequence evolution, the main sequence, problems of atmospheric instability, Luminous Blue Supergiants, Yellow Hypergiants, Wolf-Rayet stars and supernovae. 相似文献
44.
Th. De Graauw 《Space Science Reviews》1975,17(5):709-719
Conclusion For wavelengths < 50m fast and sensitive detectors are available. For wavelengths > 50m the available detectors are far from ideal. Research and development of far infrared detectors for the mixing purpose are highly recommended. 相似文献
45.
Avdeev S Bidoli V Casolino M De Grandis E Furano G Morselli A Narici L De Pascale MP Picozza P Reali E Sparvoli R Boezio M Carlson P Bonvicini W Vacchi A Zampa N Castellini G Fuglesang C Galper A Khodarovich A Ozerov Y Popov A Vavilov N Mazzenga G Ricci M Sannita WG Spillantini P 《Acta Astronautica》2002,50(8):511-525
The phenomenon of light flashes (LF) in eyes for people in space has been investigated onboard Mir. Data on particles hitting the eye have been collected with the SilEye detectors, and correlated with human observations. It is found that a nucleus in the radiation environment of Mir has roughly a 1% probability to cause an LF, whereas the proton probability is almost three orders of magnitude less. As a function of LET, the LF probability increases above 10 keV/micrometer, reaching about 5% at around 50 keV/micrometer. 相似文献
46.
V Bidoli M Casolino M P De Pascale G Furano A Morselli L Narici P Picozza E Reali R Sparvoli A M Galper A V Ozerov YuVPopov N R Vavilov A P Alexandrov S V Avdeev Y u Baturin Y u Budarin G Padalko V G Shabelnikov G Barbellini W Bonvicini A Vacchi N Zampa S Bartalucci G Mazzenga M Ricci O Adriani P Spillantini M Boezio P Carlson C Fuglesang G Castellini W G Sannita 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2000,25(10):2075-2079
The SilEye experiment aims to study the cause and processes related to the anomalous Light Flashes (LF) perceived by astronauts in orbit and their relation with Cosmic Rays. These observations will be also useful in the study of the long duration manned space flight environment. Two PC-driven silicon detector telescopes have been built and placed aboard Space Station MIR. SilEye-1 was launched in 1995 and provided particles track and LF information; the data gathered indicate a linear dependence of FLF(Hz) ( 4 2) 10(3) 5.3 1.7 10(4) Fpart(Hz) if South Atlantic Anomaly fluxes are not included. Even though higher statistic is required, this is an indication that heavy ion interactions with the eye are the main LF cause. To improve quality and quantity of measurements, a second apparatus, SilEye-2, was placed on MIR in 1997, and started work from August 1998. This instrument provides energetic information, which allows nuclear identification in selected energy ranges; we present preliminary measurements of the radiation field inside MIR performed with SilEye-2 detector in June 1998. 相似文献
47.
W. Menn O. Adriani G.C. Barbarino G.A. Bazilevskaya R. Bellotti M. Boezio E.A. Bogomolov L. Bonechi M. Bongi V. Bonvicini S. Borisov S. Bottai A. Bruno F. Cafagna D. Campana R. Carbone P. Carlson M. Casolino G. Castellini L. Consiglio M.P. De Pascale C. De Santis N. De Simone V. Di Felice A.M. Galper W. Gillard L. Grishantseva G. Jerse A.V. Karelin S.V. Koldashov S.Y. Krutkov A.N. Kvashnin A. Leonov V. Malakhov V. Malvezzi L. Marcelli A.G. Mayorov V.V. Mikhailov E. Mocchiutti A. Monaco N. Mori N. Nikonov G. Osteria F. Palma P. Papini M. Pearce P. Picozza C. Pizzolotto M. Ricci S.B. Ricciarini 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
48.
C. P. T. Groth D. L. De Zeeuw T. I. Gombosi K. G. Powell 《Space Science Reviews》1999,87(1-2):193-198
A parallel adaptive mesh refinement (AMR) scheme is described for solving the governing equations of ideal magnetohydrodynamics
(MHD) in three space dimensions. This solution algorithm makes use of modern finite-volume numerical methodology to provide
a combination of high solution accuracy and computational robustness. Efficient and scalable implementations of the method
have been developed for massively parallel computer architectures and high performance achieved. Numerical results are discussed
for a simplified model of the initiation and evolution of coronal mass ejections (CMEs) in the inner heliosphere. The results
demonstrate the potential of this numerical tool for enhancing our understanding of coronal and solar wind plasma processes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
49.
I. De Moortel 《Space Science Reviews》2009,149(1-4):65-81
Outwardly propagating intensity disturbances are a common feature in large, quiescent coronal loop structures. In this paper, an overview is given of the observed properties and the theoretical modelling. As a large number of events have been observed and analysed, good statistical results on the estimated parameters have now been obtained. The theoretical modelling mainly focuses on two distinct aspects, namely the observed rapid damping of the perturbations, thought to be due to thermal conduction and the origin of the driver. Leakage of the solar surface p-modes is the main candidate to explain the observed periodicity, due to the strong correlation between loop position and period and the filamentary nature of the observed coronal intensity perturbations. Recent observational results appear to confirm the leakage and subsequent upward propagation of the solar surface 5 minute oscillations into the overlying atmospheric layers. 相似文献
50.
Claudio Bruno Giulio Riva Claudio Zanotti Roberto Dondè Carlo Grimaldi Luigi De Luca 《Acta Astronautica》1985,12(5):351-360
Burning of composite solid rocket propellants near the pressure deflagration limit (PDL) was studied experimentally in two different test chambers. The propellant tested was a nonmetallized ammonium perchlorate-based composite propellant (AP 84/CTPB 16). Measurements were taken of the regression rate, oscillations frequency and flame luminosity. Self-sustained oscillations were detected near the PDL that matched reasonably well the predictions of the analytical nonlinear stability theory and of the numerically solved nonlinear mathematical model. Both experimental and numerical results show the burning rate oscillations near the PDL due to statically unstable burning, that is the only combustion regime possible below a certain pressure. When pressure is further reduced the amplitude of the oscillations increases and their frequency decreases, until extinction follows abruptly below a pressure that corresponds to the PDL. 相似文献