Variations of ionospheric total electron content before three strong earthquakes in the Qinghai-Tibet region

We investigate the ionospheric total electron content (TEC) anomalies occurred in the Qinghai-Tibet region before three large earthquakes (M > 7.0). The temporal and spatial TEC variations were used to detect the ionospheric possible precursors of these earthquakes. We identified two TEC enhancements in the afternoon local time 9 days and 2–3 days before each earthquake, between which a TEC decrement occurred 3–6 days before earthquakes. These anomalies happened in the area of about 30° in latitude and the maximum is localized equatorward from the epicenters. These TEC anomalies can be found in all three earthquakes regardless the geomagnetic conditions. The features of these anomalies have something in common and may have differences from those caused by geomagnetic storms. Our results suggest that these ionospheric TEC perturbations may be precursors of the large earthquakes.     

卫星遥感影像外方位元素的误差传播研究

高分辨率卫星遥感影像的几何定位精度与影像外方位元素精度密切相关.文章针对单景影像直接对地定位和立体影像前方交会定位两种典型情况,对影像各外方位元素在目标几何定位中的误差传播规律进行分析比较,相关结论可供卫星姿控及相机载荷设计方参考.     

MTF对立体测绘高程精度影响研究

MTF（调制传递函数）是反映测绘相机性能的重要指标,研究MTF对测绘高程精度的影响可以对相机的设计指标提出要求,对提高测绘精度具有极其重要的意义。文章通过计算机仿真的方法进行研究,利用3DStudioMax软件构建三维模型与模拟成像、用Harris算子提取图像特征点,并用奇异值分解与最小二乘法进行特征点的匹配,通过前方...     

气相色谱法检测无水肼中水含量的不确定度评定

对气相色谱法检测无水肼中水含量过程的不确定度进行评定,系统分析检测过程中不确定度来源和各不确定度分量对分析结果的影响,通过对不确定度的分量进行分析和合成,可知标准溶液配制的过程、标准曲线的拟合和测量样品时的重复操作带来的不确定度分量是影响无水肼中水含量测定不确定度的主要来源.     

流行词“山寨”的英译分析

随着东西方文化多渠道、全方位的接触与交流,大量反映当代中华文化的流行词汇已融入西方文化和英语词汇,"山寨"便是其中之一。今天的"山寨"已从最初的经济行为上升到社会文化的高度,其含义还在不断发展和延伸中。英译"山寨"并非易事,通过分析对比,音译才是最合适的译法。     

多飞行器突防打击一体化微分对策制导律设计

针对多进攻弹突防弹群拦截再打击目标的交战场景,提出了一种可应用于对手信息不完全情况下的微分对策制导方法。建立多飞行器交战的线性化模型,并依据不同对抗组进行模型降阶。引入时间算子统一所有分组的终端时间,基于二人零和微分理论给出制导律。利用扩展卡尔曼滤波(EKF)实现对拦截弹和目标的状态估计,并将估计应用于所提制导律。在对手状态信息已知时,仿真突防脱靶量大于5 m,拦截脱靶量小于0.1 m。而在只给定粗糙有噪声观测的不完全信息下,滤波器对拦截弹与目标的状态估计误差可接受,仿真结果依然保持相近的脱靶精度。仿真结果表明,所提制导律能有效导引进攻弹规避拦截,并准确打击目标。      

缩扩孔对孔板气膜冷却效果的数值研究

从加强气膜孔内的换热量和孔板热侧的气膜覆盖两个角度来提高气膜孔壁的冷却效果,通过对气膜孔孔型的改进,提出了缩扩型气膜孔型结构,数值计算结果表明收缩进气可以强化孔内的对流换热;而扩张出气则可以使冷气出口的速度降低,气膜覆盖面更广,提高气膜的覆盖效果.与扩张孔相比,所提出的缩扩型孔在较低的吹风比下有利于改善冷却效果,而在大吹风比下则对冷却不利;然而与普通圆柱型孔相比,缩扩型孔在任何吹风比下均能改善冷却效果.      

面向航空节点的IP/LEO卫星网络移动性管理方法(英文)

Taking into chief consideration the features of aviation nodes in satellite networks, such as high moving speed, long communication distance, and high connection frequency, this article proposes an aviation-oriented mobility management method for IP/low earth orbit （LEO） satellite networks. By introducing the concept of ground station real-time coverage area, the proposed method uses ground-station-based IP addressing method and cell paging scheme to decrease the frequency of IP binding update requests as well as the paging cost. In comparison with the paging mobile IP （P-MIP） method and the handover-independent IP mobility management method, as is verified by the mathematical analysis and simulation, the proposed method could decrease the management cost. It also possesses better ability to support the aviation nodes because it is subjected to fewer influences from increased node speeds and newly coming connection rates.     

High-precision shape approximation low-thrust trajectory optimization method satisfying bi-objective index

The shape approximation method has been proven to be rapid and practicable in resolving low-thrust trajectory; however, it still faces the challenges of large deviation from the optimal solution and inability to satisfy the specific flight time and fuel mass constraints. In this paper, a modified shape approximation low-thrust model is presented, and a novel constrained optimization algorithm is developed to solve this problem. The proposed method aims at settling the bi-objective optimization o...     

同步轨道遥感器热设计和热分析

为解决遥感器在同步轨道环境温度场分析中热传导与热辐射的综合处理问题,热传导模型温度计算采用控制容积方法建立有限差分方程;热辐射模型采用奥本海姆方法计算设备表面单元之间辐射换热;根据是否被遮挡,辐射换热中表面单元角系数的计算分别采用积分和数值方法。计算结果表明,采用上述方法进行温度场分析能够有效解决热传导模型与热辐射模型的耦合,求解精度较高,遥感器设备部件稳态分析温度分布和在轨瞬态分析温度曲线变化清楚,可作为进一步精密热控设计的依据。