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161.
The Nonlinear Model of the Response of Airglow to Gravity Waves 总被引:1,自引:0,他引:1
A.V.Mikhalev 《空间科学学报》2005,25(5):490-495
In this paper, we develope a time-dependent, nonlinear, photochemical-dynamical 2-D model which is composed of 3 models: dynamical gravity wave model, middle atmospheric photochemical model, and airglow layer photochemical model. We use the model to study the effect of the gravity wave propagation on the airglow layer. The comparison between the effects of the different wavelength gravity wave on the airglow emission distributions is made. When the vertical wavelength of the gravity wave is close to or is shorter than the thickness of the airglow layer, the gravity wave can make complex structure of the airglow layer, such as the double and multi-peak structures of the airglow layers. However, the gravity wave that has long vertical wavelength can make large scale perturbation of the airglow emission distribution. 相似文献
162.
《中国航空学报》2023,36(8):115-127
The problem of contingency return from the low lunar orbit is studied. A novel two-maneuver indirect return strategy is proposed. By effectively using the Earth’s gravity to change the orbital plane of the transfer orbit, the second maneuver in the well-known three-maneuver return strategy can be removed, so the total delta-v is reduced. Compared with the single-maneuver direct return, our strategy has the advantage in that the re-entry epoch for the minimum delta-v cost can be advanced in time, with a minimum delta-v value similar to that of the direct return. The most obvious difference between our strategy and the traditional single- or multiple- maneuver strategies is that the complete transfer orbit is a patch between a two-body conic orbit and a three-body orbit instead of two conic orbits. Our strategy can serve as a useful option for contingency return from a low lunar orbit, especially when the delta-v constraint is stringent for a direct return and the contingency epoch is far away from the return window. 相似文献
163.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(5):2348-2356
Trompsburg Complex, South Africa, is obscured by the Karoo sediments, and it is not observed on the surface. Knowledge of the boundaries of the subsurface geological bodies in the region is of main interest in many applications of the Earth Sciences. There are many methods developed to delineate boundaries of subsurface geological sources such as the curvature-based method and parabola-based methods. In this study, we applied an improved approach based on parabolic curve fitting to the gradient amplitudes of gravity and magnetic data for extracting geological structures of the Trompsburg Complex. The results showed ring structures with a diameter of about 50 km, that include granitic rocks in the central part of the Trompsburg Complex. The results also demonstrated the existence of boundaries of the other structures in the south-eastern region of the Complex, which were not determined in previous studies. The result provides new information for a better understanding of the structural and tectonic features of the Trompsburg Complex. The success of this study suggests that the improved technique based on parabolic curve, is helpful in outlining the edge locations of subsurface geologic structures. 相似文献
164.
以平台式航空/海洋重力仪为基础,为降低温度变化对其惯性器件尤其是重力敏感器的影响,保证重力测量的精度,设计了一种三级五路结构的高精度温度控制系统。以包含核心惯性器件的第三级温控为例,重点分析了温控对象的建模、非线性PI控制器的设计等问题,并进行了仿真分析和高低温环境下的试验验证,结果表明,在-10℃~+45℃温度范围内3个温控通道的温度变化量和温度稳定性均小于0.01℃,达到了重力仪的温度控制精度要求,为重力仪实现高精度重力测量提供了有利的温度条件。 相似文献
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《中国航空学报》2022,35(8):132-142
Solar power satellite receives great attention because it can release the energy crisis and environmental problems in the future. However, the launch and maintenance costs are tremendous due to the large system mass and large fuel consumption to counteract space perturbations. To reduce mass and fuel, a novel quasi-Sun-pointing attitude in Sun-frozen orbit is proposed. The Sun-frozen orbit has a nonzero eccentricity vector that always points towards the Sun. The quasi-Sun-pointing attitude is a periodic solution of the Sun-pointing attitude angle. Although about 3 % electricity must be given up because of the variation of Sun-pointing attitude angle, little control action is required to deal with the solar radiation pressure and gravity-gradient torque. The algorithm to obtain initial conditions is proposed. The influences of system parameters and structural flexibilities are studied. Simulation results reveal that the quasi-Sun-pointing attitude in Sun-frozen orbit dramatically reduce fuel consumption, the dry mass, and complexity of the control system. In addition, structural vibration is hardly induced by the gravity-gradient torque. Thus, the bending stiffness as well as the mass of the supporting structure can be reduced. 相似文献
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重力梯度是重力位的二阶微分,对地球密度扰动具有更高的分辨率,能够更加精细、全面地反映重力位在空间上的变化。高精度重力梯度测量在地质调查、地球重力场测绘、惯性导航以及基础科学研究等方面发挥着重要作用。量子重力梯度仪是近年来快速发展的一种基于激光操控原子技术的新型高精度重力梯度测量设备,具有测量精度高、长期稳定性好等特点,尤其是对振动噪声具有良好的抑制效果。目前,量子重力梯度仪的最佳灵敏度可达4E/√Hz,与最先进的旋转加速度计式重力梯度仪灵敏度3E/√Hz的水平相当。本文介绍了量子重力梯度仪的基本原理和应用,并分析了其国内外研究现状,最后讨论了目前限制量子重力梯度仪灵敏度的主要因素以及未来发展方向。 相似文献