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排序方式: 共有1312条查询结果,搜索用时 15 毫秒
1.
Yi Wei Qingjun Li Fangnuan Xu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(1):393-400
A new orbit-attitude-vibration coupled dynamic model of the tethered solar power satellite (Tethered SPS) is established based on absolute nodal coordinate formulation. The Hamilton’s equation of the system is derived by introducing generalized momentum through Legendre transformation. The correctness of the proposed model is verified by an example. The dynamic characteristics of the Tethered SPS are studied using the symplectic Runge-Kutta method. Simulation results show that the orbital radius and the total energy of the system are well preserved. The attitude of the system is unstable when the mass of the bus system is small. However, the attitude stability is dependent on some other parameters of the system, which requires further studies. It is also found that the average tether force/deformation can be roughly estimated by simplifying the solar panel as a particle. The proposed model can be used to study the orbit-attitude-vibration coupled dynamics and control problems. 相似文献
2.
为满足设定的太阳能飞机多日连续飞行条件,依据飞行过程中当前时刻的飞行高度、光伏输出功率、动力电池组余量等系统状态参数,研究如何分配动力电池组充放电和电推进系统输入等功率。所用策略立足于实时功率平衡,充分利用正午前后的光伏峰值功率用于飞机爬升及充电,在午后下滑过程中利用全部光伏输出,以最大化利用光伏资源;在光伏有效输出不足时则以一定的维持功率下滑,使能量的综合损失最小。方法能够提高以预定夜间飞行高度连续多日续航的成功率,提升飞行高度、纬度、季节范围或搭载能力,或者拓展这几种飞行条件的组合域,优化太阳能飞机的适用性。 相似文献
3.
Karl-Heinz Glassmeier Ingo Richter Andrea Diedrich Günter Musmann Uli Auster Uwe Motschmann Andre Balogh Chris Carr Emanuele Cupido Andrew Coates Martin Rother Konrad Schwingenschuh Karoly Szegö Bruce Tsurutani 《Space Science Reviews》2007,128(1-4):649-670
The fluxgate magnetometer experiment onboard the ROSETTA spacecraft aims to measure the magnetic field in the interaction
region of the solar wind plasma with comet 67P/Churyumov-Gerasimenko. It consists of a system of two ultra light (about 28
g each ) triaxial fluxgate magnetometer sensors, mounted on the 1.5 m long spacecraft boom. The measurement range of each
sensor is ±16384 nT with quantization steps of 31 pT. The magnetometer sensors are operated with a time resolution of up to
0.05 s, corresponding to a bandwidth of 0–10 Hz. This performance of the RPC-MAG sensors allows detailed analyses of magnetic
field variations in the cometary environment. RPC-MAG furthermore is designed to study possible remnant magnetic fields of
the nucleus, measurements which will be done in close cooperation with the ROSETTA lander magnetometer experiment ROMAP. 相似文献
4.
A numerical procedure for the calculation of the transonic dip of airfoils in the time domain is presented. A viscous-inviscid aerodynamic interaction method is taken to calculate the unsteady aerodynamic loads. In the present case the integral boundary layer equations are coupled with the Transonic Small Disturbance (TSD) Potential Equation. The coupling between structural motion and aerodynamic loads is carried out using State Space equation. It is solved by State Transition Matrix technique. Results are presented for NACA 64A010 and NLR 7301 airfoils with structural data from Isogai and DLR, respectively. Comparisons show good agreement with other numerical results. Certain deviations of experimental data taken from literature need more insight in the detailed test conditions. 相似文献
5.
The significance of external influences on the environment of Earth and its atmosphere has become evident during recent years.
Especially, on time scales of several hundred years, the cosmogenic isotope concentration during the Wolf-, Spoerer-, Maunder-
and Dalton-Minimum indicates an increased cosmic ray flux. Because these grand minima of solar activity coincide with cold
periods, a correlation of the Earth climate with the cosmic ray intensities is plausible. Any quantitative study of the effects
of energetic particles on the atmosphere and environment of the Earth must address their transport to Earth and their interactions
with the Earth’s atmosphere including their filtering by the terrestrial magnetosphere. The first problem is one of the fundamental
problems in modern cosmic ray astrophysics, and corresponding studies began in the 1960s based on Parker’s cosmic ray modulation
theory taking into account diffusion, convection, adiabatic deceleration, and (later) the drift of energetic particles in
the global heliospheric magnetic field. It is well established that all of these processes determining the modulation of cosmic
rays are depending on parameters that are varying with the solar magnetic cycle. Therefore, the galactic cosmic ray intensities
close to Earth is the result of a complex modulation of the interstellar galactic spectrum within the heliosphere. The modern
view of this cosmic ray modulation is summarized in our contribution. 相似文献
6.
Aprajita Verma Vassilis Charmandaris Ulrich Klaas Dieter Lutz Martin Haas 《Space Science Reviews》2005,119(1-4):355-407
Some of the most ‘active’ galaxies in the Universe are obscured by large quantities of dust and emit a substantial fraction
of their bolometric luminosity in the infrared. Observations of these infrared luminous galaxies with the Infrared Space Observatory
(ISO) have provided a relatively unabsorbed view to the sources fuelling this active emission. The improved sensitivity, spatial
resolution and spectroscopic capability of ISO over its predecessor Infrared Astronomical Satellite (IRAS) of enabled significant
advances in the understanding of the infrared properties of active galaxies. ISO surveyed a wide range of active galaxies
which, in the context of this review, includes those powered by intense bursts of star formation as well as those containing
a dominant active galactic nucleus (AGN). Mid-infrared imaging resolved for the first time the dust enshrouded nuclei in many
nearby galaxies, while a new era in infrared spectroscopy was opened by probing a wealth of atomic, ionic and molecular lines
as well as broad band features in the mid- and far-infrared. This was particularly useful, since it resulted in the understanding
of the power production, excitation and fuelling mechanisms in the nuclei of active galaxies including the intriguing but
so far elusive ultraluminous infrared galaxies. Detailed studies of various classes of AGN and quasars greatly improved our
understanding of the unification scenario. Far-infrared imaging and photometry revealed the presence of a new very cold dust
component in galaxies and furthered our knowledge of the far-infrared properties of faint starbursts, ULIGs and quasars. We
summarise almost nine years of key results based on ISO data spanning the full range of luminosity and type of active galaxies. 相似文献
7.
Joris A. D. L. Blommaert Jan Cami Ryszard Szczerba Michael J. Barlow 《Space Science Reviews》2005,119(1-4):215-243
A large fraction of ISO observing time was used to study the late stages of stellar evolution. Many molecular and solid state
features, including crystalline silicates and the rotational lines of water vapour, were detected for the first time in the
spectra of (post-)Asymptotic Giant Branch (AGB) stars. Their analysis has greatly improved our knowledge of stellar atmospheres
and circumstellar environments. A surprising number of objects, particularly young planetary nebulae with Wolf-Rayet (WR)
central stars, were found to exhibit emission features in their ISO spectra that are characteristic of both oxygen-rich and
carbon-rich dust species, while far-IR observations of the PDR around NGC 7027 led to the first detections of the rotational
line spectra of CH and CH+.
Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries:
France, Germany, The Netherlands, and the United Kingdom), and with the participation of ISAS and NASA. 相似文献
8.
L. B. F. M. Waters 《Space Science Reviews》1992,61(1-2):25-43
In this review the IR emission from circumstellar material is discussed, both of ionized gas and dust grains, and the astrophysical information that can be extracted from such observations. Some emphasis is placed on the possibilities of stellar IR astronomy using a large space-borne telescope, especially with respect to the much better spatial and spectral resolution of such a telescope compared to the current generation of ground-based and space IR telescopes. 相似文献
9.
Although the elemental composition in all parts of the solar photosphere appears to be the same this is clearly not the case
with the solar upper atmosphere (SUA). Spectroscopic studies show that in the corona elemental composition along solar equatorial
regions is usually different from polar regions; composition in quiet Sun regions is often different from coronal hole and
active region compositions and the transition region composition is frequently different from the coronal composition along
the same line of sight. In the following two issues are discussed. The first involves abundance ratios between the high-FIP
O and Ne and the low-FIP Mg and Fe that are important for meaningful comparisons between photospheric and SUA compositions
and the second involves a review of composition and time variability of SUA plasmas at heights of 1.0≤h≤1.5R
⊙. 相似文献
10.
The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest
dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006.
We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the Universe)
and others of which there are always many, like meteors and molecules, black holes and binaries. 相似文献