置信检验理论

本文提出了母体特征值置信分布的概念,建立了置信检验理论,该理论包括强检验、弱检验和弱强检验三种检验方法,分别满足了不同工程检验的需求。与假设检验相比,置信检验依据的是"大概率原则",而显著性假设检验依据的是"小概率原则",因此,置信检验能够以高概率确认工程中所关心的"条件"是否成立(如产品合格与否),能够对产品质量进行高精度的检验和控制,克服了显著性假设检验仅仅是一种拒绝检验,当接受一个假设时也只是意味着不拒绝该假设的缺点。置信检验不但能够大大提高工程检验精度,而且更加便于工程应用。      

直升机惯性传感器结构的模态优化

提出了一种基于迭代抽样和径向基插值的自适应代理模型方法。这种自适应方法以减少仿真计算数量和提高代理模型自适应能力为目的,使用多岛遗传算法选择新增样本点并使新增样本点位于设计空间的稀疏区域,使得所有的样本点均匀分布于设计空间。标准误差用来判断代理模型的精度大小以决定是否对代理模型进行更新。这种自适应代理模型结合多岛遗传算法对直升机的惯性传感器结构模态进行优化。用拉丁超立方抽样方法选择10个样本点构建初始的代理模型,自适应代理模型的计算结果表明2%的误差条件下需要额外增加7个样本点。优化结果表明不同的权重系数对最优模态特性的影响很大,惯性传感器结构的一至六阶模态值更加远离直升机的激励频率。     

月面采样相机的热设计与热分析

月面采样相机安装于月球无人采样返回探测器的机械臂上,其质量小,热耗较大,长期工作在高温环境中,故温度水平成为影响相机能否正常工作的重要因素,须予以分析。文章根据相机工作模式和机械臂的姿态运动特性,构建出适应机械臂运动的热分析模型,提出几种实现相机高温散热的方法,通过对比分析,分别确定了基于OSR涂层和白漆的热控方案,并推演了散热窗口的临界模型,为后续器外设备热设计提供借鉴思路。     

Automatic detection of geomagnetic sudden commencement via time–frequency clusters

One of global processes in ionosphere–thermosphere–magnetosphere system is the geomagnetic storms. It is of great importance to develop an algorithm that auto-detects sudden commencement because it could be an indicator of onset of the geomagnetic storm. Automatic detection of geomagnetic sudden commencement is based on time–frequency clusters generated by spectrogram. Proposed algorithm is tested on data set collected from stations belong to the international real-time magnetic observatory network (INTERMAGNET). Maximum standard deviation of algorithm detection times is observed to be one minute of the corresponding arrival times published by National Geophysical Data Center (NGDC).     

面向机载综合监视系统的ADS-B技术综述

广播式自动相关监视（ADS-B）作为机载综合监视系统（ISS）的新增重要组成部分,在保证飞机飞行安全的前提下,在监视成本和效率方面展现出优势,引领了未来监视技术的发展。本文首先介绍了ADS-B系统功能与优劣势,梳理了国内外技术和产品现状;然后从保障飞行安全和高效的角度出发,分析和综述了机载ISS中ADS-B的关键技术,并详细阐述了技术内涵及难点;最后结合下一代空域运行理念,探讨和展望了技术发展趋势,提出了4个ADS-B技术的未来发展方向,为推动ADS-B技术在实际运行与理论研究方面的发展提供参考。     

分数阶Fourier域非均匀采样Chirp信号的频谱研究

文中提出了一种自适应非均匀采样方法,并利用分数阶Fourier变换对这类非均匀采样信号在分数阶域的频谱进行了分析和研究,得到了这类非均匀采样信号在分数阶域的数字谱表达式;进一步得到了非均匀采样Chirp信号的分数阶频谱表达式;最后,通过仿真验证了结论。     

一种改进的航空发动机结构概率风险评估方法

针对航空发动机适航条款FAR33.75中关于发动机限寿件(ELLP)结构失效概率要求,提出了一种基于Kriging和蒙特卡罗半径外重要抽样(MCROIS)混合的结构概率风险评估方法。该方法针对ELLP高维、小失效概率事件以及极限状态函数为隐式、高度非线性的特点,利用Kriging元模型模拟隐式极限状态函数,然后通过主动学习迭代算法,计算最优点(MPP,最接近设计验算点的样本点),更新实验设计(DOE)并提高Kriging元模型的模拟精度。在此基础上,利用Kriging元模型确定最优抽样半径,构造半径外重要抽样密度函数,在最优抽样半径确定区域进行抽样,通过构造主动学习函数,使样本点更多落在抽样半径确定的球区域附近,加速失效概率计算的收敛,并构建了ELLP风险概率模型,解决了高维、小失效概率事件以及隐式、非线性极限状态函数的发动机结构概率风险评估难题,以某型发动机低压压气机轮盘为应用示例,与传统的蒙特卡罗仿真(MCS)方法进行了对比,验证了该方法的高效率、鲁棒性和仿真精度。     

自动阻抗调配器的校准技术探讨

自动阻抗调配器在微电子行业应用越来越广泛,但是目前国内还没有计量技术机构开展该类仪器的计量校准工作,本文介绍了其机械结构、工作原理,设计了控制模型,组建了校准系统,实现了主要参数矢量重复性、驻波比和插入损耗的校准工作。     

Systematic examination of the geomagnetic storm sudden commencement using multi resolution analysis

Geomagnetic storm sudden commencements (SSC) contain a wealth of information which is useful in many applications. It is important to point out that the SSCs used in this study are sampled at the rate of one sample per second in order get use of such high resolution data. In this paper, two studies are made on the geomagnetic SSC and an SSC onset automatic detection algorithm is introduced. The first study is about finding the relationship between the SSC rise time and its amplitude. Where it is found that there is a positive correlation between the amplitude and the amplitude gradient which is the amplitude divided by rise time. The second study is checking the spectrum of the SSC, starting from its onset until the end of the SSC rise time. This check had proved that the SSC contains both low and high frequency regions. This led us to introduce a new term, namely the SSC variation rate (VR). This VR is defined as the maximum rate of change of the field in the higher-frequency region of the SSC. These two studies were the guide to build an SSC automatic detector of one sample per second data using multi resolution analysis (MRA) of the discrete wavelet transform (DWT). The data set contains 134 SSCs with different VRs that were collected from the Circum-pan Pacific Magnetometer Network (CPMN). It is found that the standard deviation of the detection error is 41 s and that the average error is 9 s. From the calculated error distribution function, it is found that the detection error is within the range of −1.5 to 3 min. The detection process, as will be shown in the article, takes 70 s for one station and 3 min if the decision is related to the detection(s) of other stations. These results demonstrate the superiority of the proposed algorithm over other algorithms in which the detection error ranges between −8 and 5 min and the detection process takes 2–10 min. In addition to being faster and more accurate than the other algorithms, the proposed algorithm is the first algorithm that automatically detects the SSC onset times from high-resolution data unlike previous studies that focused on determining the SSC times automatically using one-minute resolution data.     

粒子滤波及其在航天器交会对接相对导航中的应用

在全面分析粒子滤波原理的基础上,提出一种改进高斯粒子滤波方法.该方法利用确定性采样滤波算法进行时间更新,替代高斯粒子滤波算法中的随机采样过程;另外,针对厚尾噪声情况,利用鲁棒统计方法对确定性采样滤波方法进行鲁棒性改进,并将其应用于所提出的改进高斯粒子滤波.将粒子滤波算法应用于交会对接相对导航问题,仿真结果表明,在多种测量噪声情况下,改进高斯粒子滤波较其他粒子滤波,能够在不过多损失估计精度的同时有效降低计算量.文中的研究成果为将粒子滤波应用于航天器导航问题提供了理论参考.