排序方式: 共有102条查询结果,搜索用时 15 毫秒
61.
Werner Schulz 《Acta Astronautica》1980,7(11):1213-1227
In 1923 Hermann Oberth published his book “Die Rakete zu den Planetenräumen” (The Rocket into Planetary Space), in 1924 Max Valier's book “Der Vorstoss in den Weltenraum” (The Advance into Space) appeared while in the U.S.A. already in 1919 Robert H. Goddard reported on his rocket experiments. Altogether different from the publications just mentioned was a book entitled “Die Erreichbarkeit der Himmelskörper” (The Attainability of Celestial Bodies) published in 1925. Its author was Dr.-Ing. Walter Hohmann, born 18 March 1880, civil engineer for the city authorities of Essen, who had already made, during World War I, calculations as to the amount of fuel, initial mass and flight time necessary for flights from the Earth to other planets. The transfer trajectories investigated by Hohmann and today attributed with his name have a great practical significance for space flight onto the present. In the lecture a critical appreciation of Hohmann's work is given. 相似文献
62.
Y. Pang X.H. Deng Z.G. Yuan M. Zhou M.H. Lin Z.W. Shu S.Y. Li J.F. Wang A. Balogh 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
On April 15th 2003, Cluster crossed the dayside magnetopause boundary and observed a series flux transfer events (FTEs) during the interval from 0630 to 0730 UT. During this period, the interplanetary magnetic field (IMF) showed a negative z component and a positive y component. Simultaneous corresponding transient plasma flows were identified in the near-conjugate polar ionosphere by the CUTLASS Finland HF radar, and the geomagnetic field disturbances were observed by the IMAGE ground-based magnetometers. By combing these data and applying the Cooling model, we show that the transient plasma flows and the geomagnetic field disturbances are closely related to the dayside FTEs. 相似文献
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R. Werner K. Stebel H.G. Hansen U.-P. Hoppe M. Gausa R. Kivi P. von der Gathen Y. Orsolini N. Kilifarska 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The geographic area at high latitudes beyond the polar circle is characterized with long darkness during the winter (polar night) and with a long summertime insolation (polar day). Consequentially, the polar vortex is formed and the surrounding strong polar jet is characterized by a strong potential vorticity gradient representing a horizontal transport barrier. The ozone dynamics of the lower and middle stratosphere is controlled both by chemical destruction processes and transport processes. 相似文献
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Walls B. McClelland M. Persyn S. Werner D.-M. 《Aerospace and Electronic Systems Magazine, IEEE》2002,17(7):9-13
The advent of NASA-JPL's X2000 architecture has brought compactPCI (cPCI) to the forefront as the system bus of choice for space data processing. This paper presents a hybrid architecture allowing the inclusion of new, high performance cPCI modules with heritage VME-based modules. The hybrid system yields a cost-effective, performance optimized processing solution for space 相似文献
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Andreas Rittweger Werner Beuchel Martin G. Andersen Jochen Albus 《Acta Astronautica》2005,57(12):877-886
The dynamic qualification of the new cryogenic upper stage ESC-A of the ARIANE 5 is supported by several tests in order to verify the assumptions and the modeling approach made at the beginning of the development. The stage contains a large amount of equipment such as propellant lines, acceleration rockets, batteries, fluid control equipment etc. For the low frequency domain the verification of the equipment responses in the integrated state was done by a sine vibration test, excited to levels representing the predicted flight loads including a qualification factor. Acoustic tests with the upper stage were performed to verify the random vibration responses in the frequency range up to 2000 Hz. To verify the shock response level induced by stage separation (pyro-shock) a stage separation test was performed. The paper concentrates on the experience made with the modal identification and sine vibration test of the stage. For the sine vibration test an electro-dynamic multi-shaker table was used. It was able to produce the required input precisely up to as specified, not an easy task for a test set-up of 20 tons weight. The paper presents the approach of how the dynamic qualification was reached successfully and highlights the experience accomplished. 相似文献
69.
M. K. Dougherty S. Kellock D. J. Southwood A. Balogh E. J. Smith B. T. Tsurutani B. Gerlach K.-H. Glassmeier F. Gleim C. T. Russell G. Erdos F. M. Neubauer S. W. H. Cowley 《Space Science Reviews》2004,114(1-4):331-383
The dual technique magnetometer system onboard the Cassini orbiter is described. This instrument consists of vector helium and fluxgate magnetometers with the capability to operate the helium device in a scalar mode. This special mode is used near the planet in order to determine with very high accuracy the interior field of the planet. The orbital mission will lead to a detailed understanding of the Saturn/Titan system including measurements of the planetary magnetosphere, and the interactions of Saturn with the solar wind, of Titan with its environments, and of the icy satellites within the magnetosphere.This revised version was published online in July 2005 with a corrected cover date. 相似文献
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J. S. Kaastra A. M. Bykov S. Schindler J. A. M. Bleeker S. Borgani A. Diaferio K. Dolag F. Durret J. Nevalainen T. Ohashi F. B. S. Paerels V. Petrosian Y. Rephaeli P. Richter J. Schaye N. Werner 《Space Science Reviews》2008,134(1-4):1-6
We present the work of an international team at the International Space Science Institute (ISSI) in Bern that worked together
to review the current observational and theoretical status of the non-virialised X-ray emission components in clusters of
galaxies. The subject is important for the study of large-scale hierarchical structure formation and to shed light on the
“missing baryon” problem. The topics of the team work include thermal emission and absorption from the warm-hot intergalactic
medium, non-thermal X-ray emission in clusters of galaxies, physical processes and chemical enrichment of this medium and
clusters of galaxies, and the relationship between all these processes. One of the main goals of the team is to write and
discuss a series of review papers on this subject. These reviews are intended as introductory text and reference for scientists
wishing to work actively in this field. The team consists of sixteen experts in observations, theory and numerical simulations. 相似文献