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521.
522.
The paper discusses the relevance of eccentric reference orbits on the dynamics of a tethered formation, when a massive cable model is included in the analysis of a multi-tethered satellite formation. The formations examined in this study are hub-and-spoke (HAS) and closed-hub-and-spoke (CHAS) configurations for in-plane and Earth-facing spin planes. Stability of the formations is studied by means of numerical simulation, together with the evaluation of the effects of eccentricity on tether elongation, agents relative position, and formation orientation and shape. 相似文献
523.
In the current study, the effects of a combined application between micro-vortex generator and boundary layer suction on the flow characteristics of a high-load compressor cascade are investigated. The micro-vortex generator with a special configuration and the longitudinal suction slot are adopted. The calculated results show that a reverse flow region, which is considered the main reason for occurring stall at 7.9° incidence, grows and collapses rapidly near the leading edge and leads to two critical points occurring on the end-wall with the increasing incidence in the baseline. As the micro-vortex generator is introduced in the baseline cascade, the corner separation is switched to a trailing edge separation by the thrust from the induced vortex. Meanwhile, the occurrence of failure is delayed due to the mixed low energy fluid and main flow. The synergistic effects between the micro-vortex generator and the boundary layer suction on the performance of the cascade are superior to the baseline at all the incidence conditions before the occurrence of failure, and the sudden deterioration of the cascade occurs at 10.3° incidence. The optimal results show that the farther upstream suction position, the lower total pressure loss of the cascade with vortex generator at the near stall condition. Moreover, the induced vortex with a leg can migrate the accumulated low energy fluid backward to delay the occurrence of stall. 相似文献
524.
在党的基层组织和广大党员中开展创先争优活动,是党的十七大作出的重大部署,通过创先争优活动的开展,在高校基层党组织和党员队伍中培养、发现、树立、运用先进优秀的好榜样,发挥先进、优秀好榜样的作用,尤其是学生党员在学生中的标杆的树立和作用的发挥。本文在学院目前党校教育的基础之上,进行分析研究,总结经验,开拓创新,寻找增强和提高学生党员的党员意识和党员素质的好方法,好途径,使得学生党员的作用在学生群体中得到更好地发挥,学生党员先进性得到更好的体现,从而着力加强大学生党建工作。 相似文献
525.
彭玉旺 《华北航天工业学院学报》2009,(1):25-29
考虑到合同法上传统的救济制度在保护消费者利益方面的不足,通过立法的方式赋予消费者在特定的消费合同领域以撤回权,理应成为我国未来有关消费者保护立法上的必然选择。本文参照德国《民法典》关于消费者撤回权的规定并结合我国现有立法关于消费者撤回权的规定,对如何完善以及构建适合我国国情的消费者撤回权制度提出了自己的一些看法。 相似文献
526.
通过分析空泡溃灭压力典型脉冲特征,设计了一套水发射试验装置和相应的验证性试验方案。验证性试验结果分析表明:弹丸出筒速度重复性较好,空气腔压力与弹丸速度关系符合物理规律,可信度强;采用水发射试验装置所测的压力曲线与空泡溃灭压力脉冲曲线基本一致,均类似半正弦,脉宽基本一致,可以进行空泡溃灭压力脉冲的初步研究。 相似文献
527.
在需求分析理论的指导下,通过调查和分析高职学生英语职业能力的需求和现状,发现现阶段的高职大学英语教学的不足,学生对职业英语的学习有着迫切需要,并且提出高职英语教学应融入职业英语教育,根据职业岗位对英语的需求进行课程改革。 相似文献
528.
In contemporary orbital missions, workloads are so high and varied that crew may rarely experience stretches of monotony. However, in historical long duration missions, occurrences of monotony were, indeed, reported anecdotally by crew. Of the effective countermeasures that appear to be at hand, many rely on visual or logistical proximity to the Earth, and are not feasible in the remote context of an extended deep space mission scenario. There, particularly in- and outbound cruising stages would be characterised by longer, comparably uneventful periods of low workload, coupled with confinement and unchanging vehicle surroundings. 相似文献
529.
Jinlu Hu Liang Jin Xiaojuan Wang Wenkai Cai Yongding Liu Gaohong Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The present study investigated the physiological and biochemical characteristics of Scytonema javanicum, a pioneer species isolated from desert biological crusts, under salinity stress. Pigment analysis showed that salinity decreased chlorophyll a and phycocyanin content, while low salinity increased carotenoid concentration and high salinity decreased carotenoid concentration. Salinity also inhibited CO2 assimilation rate and photosynthetic oxygen evolution in this cyanobacterium. Chlorophyll a fluorescence transient parameters (φPo, φEo, ψO, RC/ABS, RC/CS, PIABS, and PICS) were decreased under salt stress, while dVo/dto(Mo), Vj and φDo were increased. The decrease of ETRmax and Yield and the change of chlorophyll a fluorescence transients showed that salt stress had an important influence on photosynthesis. These results indicated that the effects of salinity stress on photosynthesis in S. javanicum may depend on the inhibition of electron transport and the inactivation of the reaction centers, but this inhibition may occur in the electron transport pathway at the PSII donor and acceptor sites. 相似文献
530.
为了解决非合作目标的相对测量问题,提出了一种基于单目图像序列目标重构结果的非合作目标相对位姿测量方法。该方法将目标的三维重构与相机的位姿信息计算相结合,首先利用观测前期得到的图像序列,通过非线性优化算法计算得到目标上部分三维点坐标;然后基于该三维点集合,建立递推深度模型,对相机的相对位姿信息和新观测到的目标点同时进行卡尔曼滤波估计。航拍测量试验表明,随着图片数量的增多,精确重构点的比例(重投影误差小于1个像素的点)不断提高,80%的图像中精确重构点比例优于89%;基于公共数据集的试验表明,该算法对姿态估算精度可达1°以内,位置测量的精度可达到2cm以内。以上试验结果表明,该算法具有较高的测量精度。 相似文献