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周同礼 《南京航空航天大学学报》1988,(3)
用火箭助推起飞是广泛应用的无人机起飞的一种方式,它和用起飞车助跑起飞方式相比有一些优越之处。本文总结了在某型无人机采用火箭助推起飞时的飞行轨道研究中探讨过的几个问题,包括发射参数的选择原则和发射起飞过程中的一些特殊问题.如力矩平衡问题,无人机和滑轨之间相对运动问题等。 相似文献
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M.A. Van Zele A. Meza 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
This paper studies the efficiency of geomagnetic solar flare effects (gsfe) in X solar flare detection; so during the period 1999–2007 a comparison between solar flare (sf) observed by satellites of the Geostationary Operational Environmental Satellite (GOES) programme and gsfe published by the Service International des Indices Geomagnetiques (SIIG) is made. 相似文献
14.
S. Sundaresan B. Nageswara Rao 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
This paper presents a mathematical model to simulate ionospheric plasma drifts at equatorial low latitude regions by coupling of E- and F-regions. The governing non-linear differential equations (of elliptic and parabolic nature) are solved numerically through finite-difference schemes and obtained neutral winds and electric fields. The temperature and electron density profiles are generated utilizing MSIS-86 atmospheric model. The continuity equation is employed to obtain night-time E-region density profile using measured ionograms at Trivandrum (India). The computed vertical and zonal plasma drifts are comparable with measured Jacamarca plasma drifts with little variations during noon and evening times. The plasma drifts at Trivandrum (8.5° N, 76.5° E, dip 0.5° N) are compared with those of Jicamarca (12° S, 76.9° W, dip 2° N). Neutral wind simulations of present model agree well with those of horizontal wind model (HWM-93). The post-sunset enhancement and its reversal are also discussed. 相似文献
15.
C. Satirapod I. Trisirisatayawong L. Fleitout J.D. Garaud W.J.F. Simons 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Following previous findings from ongoing GPS research in Thailand since 2004 we continue to exploit the GPS technique to monitor and model land motions induced by the Sumatra–Andaman Earthquake. Our latest results show that up to the end of 2010, Thailand has been co-seismically displaced and is subsequently undergoing a post-seismic horizontal deformation with total displacements (co-seismic plus post-seismic) ranging from 10.5 to 74.7 cm. We observed the largest horizontal displacements in the southern part of Thailand and moderate and small displacements in the central and northern parts. In addition to horizontal displacements throughout Thailand, continuous GPS measurements show that large parts of Thailand are subsiding at rates up to 1 cm/yr. It is the first time that such vertical post-seismic deformations at large distances (650–1500 km away from the Earthquake’s epicentre) have been recorded. We have investigated the physical processes leading to the observed subsidence. While after-slip on the subduction interface induces negligible or even slightly positive vertical motions, relaxation in the asthenosphere is associated with a sizable subsidence. Predictions from a 3D finite element model feature an asthenosphere with an effective viscosity of the order of 3 * 1018 Pas, fit the horizontal post-seismic data and the observed subsidence well. This model is then used to predict the subsidence over the whole seismic cycle. The subsidence should go on with a diminishing rate through the next two decades and its final magnitude should not exceed 10 cm in the Bangkok area. 相似文献
16.
气动式溜车-管路系统是近年来兴起的一种高效的中,长距,离输送装置,它克服了常规运输系统运费高,噪声大和污染环境的缺点,在工程上有着良好的应用前景。本文对该系统的原理和原理和结构进行了较为细致的分析,并介绍了一个应用实例。 相似文献
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针对可重复使用运载火箭垂直回收轨迹优化问题,提出了一种带有最优终端时间估计策略的hp伪谱同伦凸优化在线轨迹规划算法。首先,考虑状态约束和过程约束的非凸性,采用无损凸化处理推力幅值约束;然后,结合同伦方法与不动点迭代思想将气动力与非凸质量约束转化为线性时变剖面,完成问题凸化;进一步基于hp flipped Radau伪谱法对问题进行离散化处理,将最优控制问题转化为参数优化问题,进而采用原-对偶内点法求解;最后,为进一步减少燃料消耗,提升经济效益,考虑最优终端时间难以在线确定的问题,结合解析推导与二次插值法,设计了最优终端时间快速估计策略。仿真结果表明所设计的轨迹优化算法最优终端时间估计速度快,收敛性能良好,具有较高的精度和计算效率,具备在线应用的潜力。 相似文献
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本文对捷联系统在垂直发射战术导弹中的工程应用问题作了较深入的探讨。这些问题包括如何使用弹体姿态信息,如何判别计算误差,采用怎样的初始对准方法以及如何描述动态特性等。 相似文献
20.
The occurrence of geometric orientation illusions and the perception of ambiguous figures were analyzed in 24 subjects during static body tilt relative to gravity on Earth. Results showed that illusions such as the Rock's diamond/square, the Ponzo illusion, and orientation contrast illusions occurred less frequently, and that depth reversal of ambiguous figures took more time when subjects were lying on their side or supine compared to upright, thus suggesting that the gravitational reference plays a significant role in these “visual” illusions. The structure of images, our representation of the environment, and orientation relative to gravity are all integral parts in interpreting visual images. In a weightless environment where no gravitational reference can be used, it is expected that similar alterations in visual perception will occur. 相似文献