首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   30篇
  免费   0篇
航空   9篇
航天技术   7篇
综合类   2篇
航天   12篇
  2017年   1篇
  2016年   3篇
  2014年   1篇
  2013年   1篇
  2012年   1篇
  2011年   1篇
  2009年   2篇
  2008年   4篇
  2007年   1篇
  2005年   3篇
  2002年   1篇
  2001年   4篇
  1996年   3篇
  1985年   1篇
  1984年   1篇
  1968年   1篇
  1967年   1篇
排序方式: 共有30条查询结果,搜索用时 211 毫秒
21.
The French space adventure started more than 40 years ago. Its rich and long scientific and technical tradition made France able to occupy the place which is hers today. But what does happen to the world of arts, to which the French culture brought so much? Beyond some French artists belonging to the community of the space artists, do arts constitute a true dimension of the French space activity? Conversely, did space influence the national artistic culture? This paper proposes to tackle these questions according to a retrospective historical glance and to offer some prospective reflexions.  相似文献   
22.
In November 1986, more than 20 years ago, an H8 upper stage of Ariane 1 exploded in orbit nine months after the end of its mission. So as to avoid the generation of debris in low Earth orbit, a dedicated complementary development modified the design, introducing systematic passivation of the stage. Ever since this event, space debris mitigation has been a major concern for all launcher activities in Europe.After a short recall of the launchers currently operated by Arianespace as well as those currently developed by ESA with CNES, particularly for the safeguard authority, including the most promising future evolutions, the set of applicable regulations is described. These rules are fundamentally derived from the IADC Guidelines (hence the UNCOPUOS ones), translated into European Code of Conduct and in some more applicable Standards, such as the one prepared by ESA. The process of preparing ISO standards, mainly through the ECSS Working Group, is also described.Three major families can be identified: minimization of Mission Related Objects, Passivation of stages at the end of mission, and orbital protected zones including the so-called 25-year rule.The paper describes how European launchers do or will fulfill these applicable standards, quantifying the efficiency of the mitigation rules, and describing improvement actions currently under study.  相似文献   
23.
ISO performed a large variety of observing programmes on comets, asteroids and zodiacal light – covering about 1% of the archived observations – with a surprisingly rewarding scientific return. Outstanding results were related to the exceptionally bright comet Hale–Bopp and to ISO's capability to study in detail the water spectrum in a direct way. But many other results were broadly recognised: Discovery of new molecules in comets, the studies of crystalline silicates, the work on asteroid surface mineralogy, results from thermophysical studies of asteroids, a new determination of the asteroid number density in the main-belt and last but not least, the investigations on the spatial and spectral features of the zodiacal light.  相似文献   
24.
To achieve the size reductions needed to lower the costs of space imaging, every part of a satellite (telescope, detector, digitization, image compression, memory, telemetry, and of course satellite platform) has to be improved. With regard to the instrument, new dimensioning rules, new optical designs, and new detection systems allow significant gains. Better balance between detector and optics modulation transfer function (MTF) performances can be achieved. Though the involved solutions raise the question of signal level, the latter can be solved with the use of TDI (Time Delay and Integration) detection. The instrumental choices, the optical system under investigation and how the above techniques are allowed for in the next generation SPOT satellites development studies led by CNES will be presented in this paper, showing how they can achieve the goal of weight reductions.  相似文献   
25.
The Jupiter Energetic Particle Detector Instruments (JEDI) on the Juno Jupiter polar-orbiting, atmosphere-skimming, mission to Jupiter will coordinate with the several other space physics instruments on the Juno spacecraft to characterize and understand the space environment of Jupiter’s polar regions, and specifically to understand the generation of Jupiter’s powerful aurora. JEDI comprises 3 nearly-identical instruments and measures at minimum the energy, angle, and ion composition distributions of ions with energies from H:20 keV and O: 50 keV to >1 MeV, and the energy and angle distribution of electrons from <40 to >500 keV. Each JEDI instrument uses microchannel plates (MCP) and thin foils to measure the times of flight (TOF) of incoming ions and the pulse height associated with the interaction of ions with the foils, and it uses solid state detectors (SSD’s) to measure the total energy (E) of both the ions and the electrons. The MCP anodes and the SSD arrays are configured to determine the directions of arrivals of the incoming charged particles. The instruments also use fast triple coincidence and optimum shielding to suppress penetrating background radiation and incoming UV foreground. Here we describe the science objectives of JEDI, the science and measurement requirements, the challenges that the JEDI team had in meeting these requirements, the design and operation of the JEDI instruments, their calibrated performances, the JEDI inflight and ground operations, and the initial measurements of the JEDI instruments in interplanetary space following the Juno launch on 5 August 2011. Juno will begin its prime science operations, comprising 32 orbits with dimensions 1.1×40 RJ, in mid-2016.  相似文献   
26.
基于基因算法与博弈论的气动高升力优化   总被引:3,自引:0,他引:3  
A multi-objective evolutionary optimization method (combining genetic algorithms(GAs)and game theory(GT))is presented for high lift multi-airfoil systems in aerospace engineering.Due to large dimension global op-timization problems and the increasing importance of low cost distributed parallel environments,it is a natural idea to replace a globar optimization by decentralized local sub-optimizations using GT which introduces the notion of games associated to an optimization problem.The GT/GAs combined optimization method is used for recon-struction and optimization problems by high lift multi-air-foil desing.Numerical results are favorably compared with single global GAs.The method shows teh promising robustness and efficient parallel properties of coupled GAs with different game scenarios for future advanced multi-disciplinary aerospace techmologies.  相似文献   
27.
28.
The nitrogen flow characteristics around models is studied with a view to obtaining data which determine the physical state of the plasma. Among all possible techniques, the most adaptable to the special hot-shot conditions?electrostatic probes and VHF microwave reflectometry?is chosen. The experimental apparatus and results in nitrogen are described. The ionization is not homogenous during the shot; this result seems to confirm the assumption that the plasma flow is utilizable only after a delay of more than ten milliseconds following the shock formation period. The hot-shot utilization range is examined for this type of experiment.  相似文献   
29.
A six-component force-measuring balance for impulse wind tunnels is described. The application of semiconductors for force and acceleration measurement, and their mechanical and electronic coupling for the desired operational outputs are given. The dynamic calibration procedures are explained and verified for the conditions encountered in hot-shot-type wind tunnels.  相似文献   
30.
The Baikonur launch site was the world's first and remains its most important in terms of the historic missions that have taken off from it. This article describes the background to the construction of Baikonur, the steps taken to keep it secret from the West, and its chief facilities. It enumerates the major space missions that took place there, as well as acknowledging its failures, e.g. the lunar programmes, before speculating on its future. An increasing emphasis on commercial launches seems likely.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号