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441.
442.
从硬件组成和软件设计两方面介绍了功率传感器自动校准系统.着重介绍了该系统的软件设计思路,并就其特点进行说明.该自动校准系统在Visual Basic 6.0环境下完成编程,完整地实现了登录、设备信患登记、测试、报告文件输出及查询功能,使用简便、性能可靠且人机交互良好. 相似文献
443.
飞机电源系统参数测试软件的通用性设计 总被引:1,自引:0,他引:1
从自动测试系统通用性的角度出发,阐述了ATS软件通用性的实现及关键技术.利用MFC在组件技术的基础上完成了飞机电源系统通用参数测试软件功能组件开发,同时结合GL Studio完成了图形控件的设计和开发.借助于LabWindows/CVI,给出了通用测试软件集成的详细说明和方法步骤. 相似文献
444.
Jan Laštovička 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
There are two ways of external forcing of the lower ionosphere, the region below an altitude of about 100 km: (1) From above, which is directly or indirectly of solar origin. (2) From below, which is directly or indirectly of atmospheric origin. The external forcing of solar origin consists of two general factors – solar ionizing radiation variability and space weather. The solar ionization variability consist mainly from the 11-year solar cycle, the 27-day solar rotation and solar flares, strong flares being very important phenomenon in the daytime lower ionosphere due to the enormous increase of the solar X-ray flux resulting in temporal terminating of MF and partly LF and HF radio wave propagation due to heavy absorption of radio waves. Monitoring of the sudden ionospheric disturbances (SIDs – effects of solar flares in the lower ionosphere) served in the past as an important tool of monitoring the solar activity and its impacts on the ionosphere. Space weather effects on the lower ionosphere consist of many different but often inter-related phenomena, which govern the lower ionosphere variability at high latitudes, particularly at night. The most important space weather phenomenon for the lower ionosphere is strong geomagnetic storms, which affect substantially both the high- and mid-latitude lower ionosphere. As for forcing from below, it is caused mainly by waves in the neutral atmosphere, i.e. planetary, tidal, gravity and infrasonic waves. The most important and most studied waves are planetary and gravity waves. Another channel of the troposphere coupling to the lower ionosphere is through lightning-related processes leading to sprites, blue jets etc. and their ionospheric counterparts. These phenomena occur on very short time scales. The external forcing of the lower ionosphere has observationally been studied using predominantly ground-based methods exploiting in various ways the radio wave propagation, and by sporadic rocket soundings. All the above phenomena are briefly mentioned and some of them are treated in more detail. 相似文献
445.
Rolf Bütikofer Erwin O. FlückigerLaurent Desorgher Michael R. MoserBenoît Pirard 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Close to the current solar activity minimum, two large solar cosmic ray ground-level enhancements (GLE) were recorded by the worldwide network of neutron monitors (NM). The enormous GLE on 20 January 2005 is the largest increase observed since the famous GLE in 1956, and the solar cosmic-ray event recorded on 13 December 2006 is among the largest in solar cycle 23. From the recordings of the NMs during the two GLEs, we determined the characteristics of the solar particle flux near Earth. 相似文献
446.
中承式拱桥属于柔性空间结构,主拱上承受的脉动风荷载相互干扰。以重庆菜园坝长江大桥为研究对象,进行了湍流下的主拱单拱及双拱节段模型风洞试验。对模型表面脉动压力的功率谱、相关系数、水平和竖向相干函数进行了细致分析,讨论了双拱间距宽度比对脉动压力频域特性的影响。当间距宽度比大于5时,后拱风荷载受到前拱的干扰作用。当两拱间距宽度比小于5时,前后拱风荷载特性类似于组合截面。随间距宽度比变小,主拱涡脱落折算频率和压力功率谱逐渐增大,前后拱迎风面和背风面的相关系数及相干系数均逐步降低。 相似文献
447.
在建立对Link-16数据链的干扰模型和接收机模型的基础上,分析了噪声干扰下接收机的误码性能,研究了干扰功率分配问题,并得到了对Link-16数据链的干扰功率分配方程,最后进行了仿真分析。 相似文献
448.
Corey S. Jamieson Agnes H.H. Chang Ralf I. Kaiser 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Mixtures of molecular nitrogen and methane have been identified in numerous outer Solar Systemices including the icy surfaces of Pluto and Triton. We have simulated the interaction of ionizing radiation in the Solar System by carrying out a radiolysis experiment on a methane – molecular nitrogen ice mixture with energetic electrons. We have identified the hydrogen cyanide molecule as the most prominent carbon–nitrogen-bearing reaction product formed. Upon warming the irradiated sample, we followed for the first time the kinetics and temporal evolution of the underlying acid–base chemistry which resulted in the formation of the cyanide ion from hydrogen cyanide. On the surfaces of Triton and Pluto and on comets in Oort’s cloud this sort of complex chemistry is likely to occur. In particular, hydrogen cyanide can be produced in low temperature environments (Oort cloud comets) and may be converted into cyanide ions once the comets reach the warmer regions of the Solar System. 相似文献
449.
Myung-Hee Y. Kim Matthew J. Hayat Alan H. Feiveson Francis A. Cucinotta 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
The potential for exposure to large solar particle events (SPEs) with high energy levels is a major concern during interplanetary transfer and extra-vehicular activities (EVAs) on the lunar and Mars surface. Previously, we have used data from the last 5 solar cycles to estimate percentiles of dose to a typical blood-forming organ (BFO) for a hypothetical astronaut in a nominally shielded spacecraft during a 120-d lunar mission. As part of this process, we made use of complete energy spectra for 34 large historical SPEs to calculate what the BFO mGy-Eq dose would have been in the above lunar scenario for each SPE. From these calculated doses, we then developed a prediction model for BFO dose based solely on an assumed value of integrated fluence above 30 MeV (Φ30) for an otherwise unspecified future SPE. In this study, we reasoned that since BFO dose is determined more by protons with higher energies than by those with lower energies, more accurate BFO dose prediction models could be developed using integrated fluence above 60 (Φ60) and above 100 MeV (Φ100) as predictors instead of Φ30. However to calculate the unconditional probability of a BFO dose exceeding a pre-specified limit (“BFO dose risk”), one must also take into account the distribution of the predictor (Φ30,Φ60, or Φ100), as estimated from historical SPEs. But Φ60 and Φ100 have more variability, and less available historical information on which to estimate their distributions over many SPE occurrences, than does Φ30. Therefore, when estimating BFO dose risk there is a tradeoff between increased BFO dose prediction at a given energy threshold and decreased accuracy of models for describing the distribution of that threshold over future SPEs as the threshold increases. Even when taking the second of these two factors into account, we still arrived at the conclusion that overall prediction improves as the energy level threshold increases from 30 to 60 to 100 MeV. These results can be applied to the development of approaches to improve radiation protection of astronauts and the optimization of mission planning for future space missions. 相似文献
450.
V.B. Baranov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
An interface between the fully ionized hydrogen plasma of the solar wind (SW) and the partially ionized hydrogen gas flow of the local interstellar medium (LISM) is formed as a region where there is a strong interaction between these two flows. The interface is bounded by the solar wind termination shock (TS) and the LISM bow shock (BS) and is separated on two regions by the heliopause (HP) separating the solar wind and charged component of the LISM (plasma component below). The BS is formed due to the deceleration of the supersonic LISM flow relative to the solar system. Regions of the interface between the TS and HP and between the HP and BS were in literature named as the inner and outer heliosheaths, respectively. An investigation of the structure and physical properties of the heliosheath is at present especially interested due to the fact that Voyager-1 and Voyager-2 have crossed the TS in December 2004 (Burlaga, L.F., Ness, N.F., Acuna, M.Y., et al. Crossing the termination shock into the the heliosheath. Magnetic fields. Science 309, 2027–2029, 2005; Fisk, L.A. Journey into the unknown beyond. Science 309, 2016–2017, 2005; Decker, R.B., Krimigis, S.M., Roelof, E.C., et al. Voyager 1 in the foreshock, termination shock and heliosheath. Science 309, 2020–2024, 2005; Stone, E.C., Cummings, A.C., McDonald, F.B., et al. Voyager 1 explores the termination shock region and the heliosheath beyond. Science 309, 2017–2020, 2005) and in September 2007 (Jokipii, J.R. A shock for Voyager 2. Nature 454, 38–39, 2008; Gurnett, D.A., Kurth, W.S. Intense plasma waves at and near the solar wind termination shock. Nature 454, 78–80, 2008. doi: 10.1038/nature07023; Wang, L., Lin, R.P., Larson, D.E., Luhmann, J.G. Domination of heliosheath pressure by shock-accelerated pickup ions from observations of neutral atoms. Nature 454, 81–83, 2008. doi: 10.1038/nature07068.14; Burlaga, L.F., Ness, N.F., Acuna, M.H., et al. Magnetic fields at the solar wind termination shock. Nature 454, 75–77, 2008. doi: 10.1038/nature07029; Richardson, J.D., Kasper, J.C., Wang, C., et al. Cool heliosheath plasma and deceleration of the upstream solar wind at the termination shock. Nature 454, 63–66, 2008. doi: 10.1038/nature07024; Stone, E.C., Cummings, A.C., McDonald, F.B., et al. An asymmetric solar wind termination shock. Nature 454, 71–74, 2008. doi: 10.1038/nature07022; Decker, R.B., Krimigis, S.M., Roelof, E.C., et al. Mediation of the solar wind termination shock by non-thermal ions. Nature 454, 67–70, 2008. doi: 10.1038/nature 07030), respectively, and entered to the inner heliosheath. 相似文献