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21.
测量船船摇前馈数据处理方法研究及应用 总被引:1,自引:0,他引:1
船摇前馈是航天测量船稳定性设计方法之一。实践证明,船摇前馈对改善系统误差有益,目标速度前馈特别是加速度前馈的改善效果要比船摇前馈的好。分析原因,一方面是目标相对船摇来说变化慢,低频分量多,滤波后能够比较准确地得到所要的值,前馈精度也就高;另一方面是船摇前馈值特别是加速度前馈比较难以准确获得。因此,准确地计算前馈量,是补偿测量设备伺服系统滞后造成的误差,达到高精度地跟踪目标的关键之一。本文详细给出了船摇前馈量的具体计算公式,并在卫星发射任务中进行了应用和验证。 相似文献
22.
Solar sail formation flying on an inclined Earth orbit 总被引:2,自引:0,他引:2
The versatility of solar sail propulsion can be utilized in the exploration of Earth’s magnetotail. An inclined periodic orbit with respect to ecliptic is possible for a solar sail with its orbital plane in synchronous rotation with the sun. Solar sail evolving on such an inclined orbit is free of Earth shadow. Formation flying of a cluster of sails around such an inclined periodic orbit is investigated in this paper. The solution of the first-order approximation to the linear relative motion is used to qualitatively analyze the configurations of relative orbits. Since the relative motion is unstable, active control is necessary to keep a periodic relative motion. A typical LQR method is employed to stabilize the relative motion. The design method is validated by numerical examples. 相似文献
23.
以某一两级固体地—空导弹作为算例,研究了固体火箭发动机/导弹一体化设计问题。研究以导弹起飞质量最轻和可用过载最大为目标建立了目标函数,利用优化理论完成了7个设计变量的优化设计。优化结果表明,所建立的数学模型是正确的。 相似文献
24.
Jin Wang Xiaoming Zhou Lei Qiao Wanlin Gong 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(5):1254-1259
An upgrade of Wuhan Ionospheric Backscattering Sounding System (WIOBSS) was developed in 2015. Based on the Universal Serial Bus (USB), and a high performance FPGA, the newly designed WIOBSS has a completely digital structure, which makes it portable and flexible. Two identical WIOBSSs, which were situated at Mile (24.31°N, 103.39°E) and Puer (22.74°N, 101.05°E) respectively, were used to investigate the ionospheric irregularities. The comparisons of group distance, Doppler shift and width between Mile-Puer and Puer-Mile VHF ionospheric propagation paths indicate that the reciprocity of the irregularities is satisfied at midlatitude region. The WIOBSS is robust in the detection of ionospheric irregularities. 相似文献
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龚文轩 《中国空间科学技术》1995,15(1):36-46
依据海因里奇开伞动力理论,在计算个表充满时间的连续方程中,考虑了伞顶孔,伞顶部分大透气量织物面积,以及伞衣中、下部分织物透气量对开伞动载的影响。引用了非线性的阻力特征文化曲线[2],计算伞衣充气过程中阻力特征的变化。并考虑了伞衣充气过程初始瞬时的阻力特征,假设在伞衣初始充气时期的一段时间中,进气口直径为常值,数值上等于[4(CA)0/C(st)π)](1/2)。计算实例表明,计算结果与实测数据相比较,其一致性是比较满意的。 相似文献
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Shaoqi Gong Daniel Fiifi Hagan Jing Lu Guojie Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(1):413-425
The precipitable water vapor is one of the most active gases in the atmosphere which strongly affects the climate. China's second-generation polar orbit meteorological satellite FY-3A equipped with a Medium Resolution Spectral Imager (MERSI) is able to detect atmospheric water vapor. In this paper, water vapor data from AERONET, radiosonde and MODIS were used to validate the accuracy of the MERSI water vapor product in the different seasons and climatic regions of East Asia. The results show that the values of MERSI water vapor product are relatively lower than that of the other instruments and its accuracy is generally lower. The mean bias (MB) was ?0.8 to ?12.7?mm, the root mean square error (RMSE) was 2.2–17.0?mm, and the mean absolute percentage error (MAPE) varied from 31.8% to 44.1%. On the spatial variation, the accuracy of MERSI water vapor product in a descending order was from North China, West China, Japan -Korea, East China, to South China, while the seasonal variation of accuracy was the best for winter, followed by spring, then in autumn and the lowest in summer. It was found that the errors of MERSI water vapor product was mainly due to the low accuracy of radiation calibration of the MERSI absorption channel, along with the inaccurate look-up table of apparent reflectance and water vapor within the water vapor retrieved algorithm. In addition, the surface reflectance, the mixed pixels of image cloud, the humidity and temperature of atmospheric vertical profile and the haze were also found to have affected the accuracy of MERSI water vapor product. 相似文献
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