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11.
半实物仿真试验中,要求计算机帧时间与计算积分步长相一致,但在实际试验中不容易精确地做到。本文分析了这种不一致给半实物仿真试验带来的影响,给出了解决的办法,文章中还给出了一实例来说明。 相似文献
12.
H. Thiemann R. W. Schunk 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(12):143-146
Heavy emission caused by impacting plasma ions results in a fast discharging effect of the initially large surface potentials on the dielectric solar cells. This eventually counteracts the energization process of the plasma ions to the cover glasses and leaves no significant electric fields. Thus, with an existing thermal plasma, electrons are again able to reach dielectric surfaces. Strong localized electric fields of the order of several 10 kV/cm form near the interconnector-cover glass interface. 相似文献
13.
T. J. Ponman A. M. Read 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1993,13(12):361-364
Using data from the Wide Field Camera EUV all-sky survey, we have established upper limits to the EUV flux from a sample of 30 bright, nearby, non-active spiral galaxies. These galaxies were chosen to be those most likely to be detected in the EUV on the basis of (i) low interstellar absorption within our own galaxy, (ii) brightness in other wavebands, (iii) high star formation activity, and (iv) proximity. The derived EUV upper limits are restrictive, and establish for the first time that the EUV flux escaping from galaxies does not constitute a major component of their bolometric luminosity, and in particular that it cannot be the sink for the energy injected into the interstellar medium by supernova explosions, as had been suggested following the failure to detect this power in the X-ray band. 相似文献
14.
程昕 《西安航空技术高等专科学校学报》2006,24(4):66-68
在总结以往多年教学经验的基础上,对目前体育课程发展状况进行了研究和理性思考,淮阴工学院在一年级进行体育课程改革与实践,提出“主项课”的教学模式,取得一定的成效。同时,对存在的一些主要问题提出进一步的设想和改进措施。 相似文献
15.
The authors present a new scientific space mission consisting of a satellite carrying a receiving- only SAR which receives the signal transmitted by the ENVISAT-1 SAR. The integration of ENVISAT-1 SAR and bistatic radar data offers an improved potentiality of surface classification, three-dimensional observation, and the opportunity of advanced scientific experiments in the field of bistatic scattering. The small satellite nominal orbit and the attitude manoeuvres are designed in order to maintain an adequate overlap between the two radar swaths along the whole orbit, taking into account the ENVISAT-1 attitude and pointing. A preliminary satellite design (2-year lifetime) is then performed to evaluate the orbit decay and to determine the appropriate orbit manoeuvres (every 4 days) to control the satellites relative phase. The numerical simulation shows that a spacecraft of about 584kg is able to meet the mission requirements. 相似文献
16.
In extension to common applications such as groundtrack displays and antenna steering, the SGP4 orbit model is proposed for operational orbit determination in small satellite missions. SGP4 is an analytical orbit model for Low-Earth orbiting satellites that is widely used for the propagation of NORAD twoline elements. Twoline elements may hence be generated completely independent of NORAD. Their use as exclusive source of orbital information simplifies the operations concept and reduces mission costs through the extensive use of existing low-cost mission support software. Due to small computer resource requirements of 8–10kByte, the SGP4 model may also be applied for onboard orbit computations making use of e.g. a 80186 processor, thus ensuring full compatibility of ground-based and onboard operations. The proposed approach is particularly suited in combination with a space-borne GPS receiver, were the C/A-code navigation solutions are treated as measurements that are adjusted in a least-squares sense using the SGP4 model. As consequence, inherent drawbacks of the pure navigation solutions such as data gaps and scatter as well as limited velocity accuracy are avoided, while the operational navigation activities are kept at a minimum. The feasibility of the concept is illustrated based on real GPS navigation data from the TOPEX/Poseidon and the MIR space station with an inherent data quality of 50–100 m. It is shown that 3 hours of data within a 4 day period are sufficient to keep the position error within 4 km, that is considered sufficient for most applications. 相似文献
17.
介绍了一种基于虚拟仪器结构的导弹指挥仪自动测试系统,以及该系统的硬件配置和在Lab Windows/CVI环境下的软件模块化设计. 相似文献
18.
19.
弹道靶红外辐射测量 总被引:1,自引:0,他引:1
为深入认识再入物理现象 ,在弹道靶上做了模型头部和近尾流红外辐射测量。发射器为 1 4.5mm口径的二级轻气炮 ,模型为1 0mm的球 ,材料为聚碳酸酯和铝 ,模型发射速度 4~6km/s,使用红外InSb探测器测量波长 3~ 5 .4μm的红外辐射 ,靶室压力 5 .32kPa。实验中使用光电法测量模型速度 ,两站阴影照相进行模型姿态监测和速度核实。实验结果表明 :球模型的红外辐射强度强烈依赖于模型材料和模型飞行速度。对不同材料模型头部和尾流部辐射强度的定性比较说明由于低温材料烧蚀产物的存在 ,极大地增强了头部和近尾流区的辐射强度 ,而且延长了尾流辐射长度 相似文献
20.