排序方式: 共有43条查询结果,搜索用时 31 毫秒
21.
Frits Paerels Jelle Kaastra Takaya Ohashi Philipp Richter Andrei Bykov Jukka Nevalainen 《Space Science Reviews》2008,134(1-4):405-418
We briefly review capabilities and requirements for future instrumentation in UV- and X-ray astronomy that can contribute
to advancing our understanding of the diffuse, highly ionised intergalactic medium. 相似文献
22.
23.
Stephen M. Pompea 《Space Science Reviews》1995,74(1-2):181-193
The performance of infrared and submillimeter systems can be severely degraded by stray light. Stray light includes off-axis radiation, system diffraction and scattering effects, and thermal self-emission. The purpose of this paper is to identify several keys to preventing system degradation due to stray radiation. The first key is to apply stray light design rules and analysis techniques early in the program before the design is finalized. A systems level analysis using stray light analysis software is often necessary in order to identify more subtle problems and to assess the magnitude of their effect on system performance. Another key is to address contamination control and the choice of surface coatings early in the program. The management of stray radiation issues is extremely cost-effective, if begun early in the program, and can reduce later schedule hardships. 相似文献
24.
Jan Jurčák Manuel Collados Jorrit Leenaarts Michiel van Noort Rolf Schlichenmaier 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(4):1389-1395
The European Solar Telescope (EST) is a project of a new-generation solar telescope. It has a large aperture of 4?m, which is necessary for achieving high spatial and temporal resolution. The high polarimetric sensitivity of the EST will allow to measure the magnetic field in the solar atmosphere with unprecedented precision. Here, we summarise the recent advancements in the realisation of the EST project regarding the hardware development and the refinement of the science requirements. 相似文献
25.
26.
H.S. Sawant J.R. Cecatto H. Mészárosová C. Faria F.C.R. Fernandes M. Karlický M.C. de Andrade 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
The digital, decimetric (950–2500 MHz) Brazilian Solar Spectroscope (BSS, Sawant, H.S., Subramanian, K.R., Faria, C., et al. Brazilian Solar Spectroscope (BSS). Solar Phys. 200, 167–176, 2001) with high time (10–1000 ms) and frequency (1–10 MHz) resolution is in regular operation since April, 1998, at the National Space Research Institute (INPE) at São José dos Campos, Brazil. The BSS has now been upgraded with a new digital data acquisition and data processing system. The new version of the BSS has improved the observational possibilities with the capability to record up to 200 frequency channels available in the selectable frequency range 950–2500 MHz. The GPS receiver permits the acquisition of data with time accuracy in the order of 0.1 ms. The software system of the BSS is composed by two distinct modules: the first, data acquisition system provides a flexible Graphical User Interface (GUI) that allows one to choose the observational parameters. The second module is the real time visualization system that permits real time visualization of the observed dynamic spectrum and additionally allows procedures for visualization and preliminary analysis of the recorded solar spectra. Using the new visualization system, we have realized two new types of dm-radio fine structures: narrow band type III bursts with positive as well as negative group frequency drift and dots emissions arranged in zebra-like and fiber-like chains. Furthermore, we have found flare generated fast wave trains according to their tadpole signature in wavelet power spectra for a decimetric type IV radio event (June 6, 2000 flare). 相似文献
27.
综合运用先进的GPS授时技术和数字仿真、虚拟仪器结构、可视化编程等计算机软件技术,构建新一代靶场智能型检测系统,解决对野外分散站点上测控设备进行检测、标校、监控和测控网通信联试等技术问题。着重阐述智能化检测技术在靶场的应用及发展趋势,为技术人员开发测试软件提供参考。 相似文献
28.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(2):763-771
Water masers are well-known to be variable on a variety of time scales, but only three Galactic H2O masers are known to flare to the level of 105–106 Jy ( K): Orion KL, W49N, and the recently discovered G25.65+1.05. Recently detected flaring activity of H2O maser in the massive star-forming region G25.65+1.05 gave us a unique opportunity to study the fine structure of H2O maser emission in the bursting state with extremely high space VLBI angular resolution. Observation of the source was carried out with ∼9 Earth diameter space-ground baseline within the framework of the RadioAstron project. H2O maser emission from two spectral features, including the bursting one, was detected in the experiment. Only ∼1% of the bursting H2O maser emission was detected on the space-ground baselines: it indicates the presence of a very compact spatial structure with a size of ∼25 as, which corresponds to 0.05 AU or ∼5 solar diameters at the distance to the source of 2.08 kpc, and the brightness temperature of ∼3 × 1016 K. Analysis of the flux density as a function of the baseline length for the bursting H2O maser feature in the source shows that most of the emission comes from an extended “halo” structure, while the core of emission is very compact and has an extreme brightness temperature. These results are in agreement with the model of interacting maser clouds considered as the likely explanation of the nature of the burst in the source. Under the assumption of such a model, the beam size of maser emission is reduced while the brightness temperatures similar to the highest observed values are produced. 相似文献
29.
天线视角是航天测量船的一个重要指标,通过分析各种视角遮挡情况,列出相应的视角计算方法,为船用天线视角设计提供了依据。同时本文分析了针对视角遮挡问题在船舶设计阶段应采取的措施。 相似文献
30.
Sabri Mekaoui Steven Dewitte Christian Conscience André Chevalier 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
Current measurements from DIARAD/VIRGO, PMO6V/VIRGO and ACRIM3 radiometers are of the same order of magnitude, but differ from TIM/SORCE by about 4.5 W m−2. This difference is higher than the sum of the claimed individual absolute uncertainties of the instruments. In this context, the SOLAR payload on the International Space Station embarks the SOVIM package. We give the results of the differential absolute radiometer DIARAD/SOVIM and discuss its associated uncertainties. Compared to DIARAD/VIRGO, all possible efforts have been made to improve the absolute accuracy. Substantial progress has been made in the aperture area and electrical power measurements. The measured TSI value from the left channel of DIARAD/SOVIM during three days of June 2008 is 1364.50 ± 1.38 W m−2 (Total) or ±0.49 W m−2 (if we combine the individual contributions in quadrature). The right channel gives 1364.75 W m−2 with the same uncertainties. These values are about 1.2 W m−2 lower than DIARAD/VIRGO and about 4 W m−2 higher than TIM/SORCE. The difference between the left and right channels measurements is as low as 0.25 W m−2 which is within the improved uncertainty limits. 相似文献