ICAO考试英语听力笔记初探

ICAO考试的情景对话题和听力复述题中，考生需要根据所听内容进行对话或复述短文，一方面是对听力的考察，另一方面也是对考生短时记忆的考验。关于口译的多项研究表明，系统的笔记是对短时记忆的有效辅助和补充。通过大量利用符号和缩写，听者能将听到的关键信息有目的、有条理地记录下来，帮助随后的口头表达。因此，掌握良好的笔记体系是缓解大脑压力、提升听力效率、辅助口语表达的重要环节。     

某型舵机放大器电老炼模拟负载方案论证

通过对舵机放大器电老炼各类负载进行权衡论证,研究出功率电阻与电感串联的模拟负载。经过方案论证和充分的试验,设计特定的激励信号,对该方案不断地优化和完善,最终基本模拟了电机特性。证明该方案可最大限度地模拟了实际负载电机的工作特性,更适合本单位目前的批生产状态。     

Predictive Modeling and Parameter Optimization of Cutting Forces During Orbital Drilling

To optimize cutting control parameters and provide scientific evidence for controlling cutting forces,cutting force modeling and cutting control parameter optimization are researched with one tool adopted to orbital drill holes in aluminum alloy 6061.Firstly,four cutting control parameters(tool rotation speed,tool revolution speed,axial feeding pitch and tool revolution radius)and affecting cutting forces are identified after orbital drilling kinematics analysis.Secondly,hybrid level orthogonal experiment method is utilized in modeling experiment.By nonlinear regression analysis,two quadratic prediction models for axial and radial forces are established,where the above four control parameters are used as input variables.Then,model accuracy and cutting control parameters are analyzed.Upon axial and radial forces models,two optimal combinations of cutting control parameters are obtained for processing a13mm hole,corresponding to the minimum axial force and the radial force respectively.Finally,each optimal combination is applied in verification experiment.The verification experiment results of cutting force are in good agreement with prediction model,which confirms accracy of the research method in practical production.     

月面无人自主采样返回任务动力下降点确定及验证

动力下降点确定是实施月面软着陆的重要环节，是多系统间复杂迭代的过程，涉及轨道设计、制导律设计、着陆目标的采样区确定、着陆及起飞安全分析。其设计结果直接影响了最终着陆点的位置和着陆过程的着陆安全，也间接影响采样安全和采样工程目标的实现结果。针对嫦娥五号在实施月面软着陆前确定动力下降点的任务需求，提出了通过多次轨道控制与最优标称制导轨迹搜索联合控制策略的动力下降点确定方法。首先，根据月面无人自主采样返回任务设计总结了动力下降点确定原理和约束条件；然后，详细论述了月面无人自主采样返回任务软着陆过程动力下降点确定方法；最后，通过嫦娥五号在着陆前主要的几次轨控实施结果分析了其对动力下降点的影响，同时综合了着陆区地形分析及着陆、起飞安全性分析，对动力下降点进行确定并根据最终在轨飞行结果进行验证。验证结果表明，基于“逐次逼近寻优方法”的月面软着陆环节动力下降点的确定方法有效，可以为后续地外天体软着陆等任务提供参考和借鉴。     

A novel signal processing approach for LEO space debris based on a fence-type space surveillance radar system

The increase in space debris can seriously threaten regular activities in the Low Earth Orbit (LEO) environment. Therefore, it is necessary to develop robust, efficient and reliable techniques to understand the potential motions of the LEO debris. In this paper, we propose a novel signal processing approach to detect and estimate the motions of LEO space debris that is based on a fence-type space surveillance radar system. Because of the sparse distribution of the orbiting debris through the fence in our observations, we formulate the signal detection and the motion parameter estimation as a sparse signal reconstruction problem with respect to an over-complete dictionary. Moreover, we propose a new scheme to reduce the size of the original over-complete dictionary without the loss of the important information. This new scheme is based on a careful analysis of the relations between the acceleration and the directions of arrival for the corresponding LEO space debris. Our simulation results show that the proposed approach can achieve extremely good performance in terms of the accuracy for detection and estimation. Furthermore, our simulation results demonstrate the robustness of the approach in scenarios with a low Signal-to-Noise Ratio (SNR) and the super-resolution properties. We hope our signal processing approach can stimulate further work on monitoring LEO space debris.     

自适应前馈技术在精密运动控制中的应用

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二元稀土组合物对双基推进剂燃烧催化作用研究

研究了镧（铈）／铜盐、镧／铅盐、镧／铈组合物及镧／铈焙烧复合物对双基推进剂燃烧的催化作用，发现铜盐对稀土化合物的平台催化作用的改善有利，铅盐使稀土化合物的平台催化范围向高压区移动。镧／铈组（复）合物的燃烧催化作用与镧／铈比例密切相关，且使双基推进剂产生2个以上的平台燃烧区。稀土／铜盐对双基推进剂红外透过率的贡献高于其它二元稀土组合物。     

胶焊单搭接头长时力学性能分析

胶焊是将点焊技术与胶接技术结合使用的先进连接技术。由于众多优点 ,该技术越来越受到重视和应用 ,而其相关研究特别是对其长时蠕变应力的了解比较缺乏。本文利用三维粘弹塑性有限元法 ,对胶焊连接接头的时间相关应力再分布进行分析 ,并讨论了相关接头的设计和材料选择的改进方向。     

最严重充电条件下航天器的瞬态充电模拟研究

运用等效电路模式理论推导出随时间变化充电问题的微分方程组，针对最严重情况构造了解决瞬态充电问题的程序，对ＡＴＳ－６卫星的二种情况运用这个程序进行了计算。讨论了航天器不同材料对充放电的影响。