Optomechanical optimal design configuration and analysis of glue pad bonds in lens mounting for space application

Optomechanical systems are very complex requiring a high degree of accuracy. The carrier structure of an optical system is required to maintain the position of the optical components with respect to each other within the design tolerances. The most common loads on optical systems are self-weight, due to gravity orientations, and temperature ranges, due to exposure to rapidly changing temperatures from very cold to very hot and during launch. The fixing should ensure mechanical stability and thus accurate positioning in various gravity orientations.In order to ensure reliability during a space flight mission, the optomechanical engineer must understand the requirements of the space flight environment as well as the physics of failure of the optical components themselves; this can minimize the risks of on-orbit failure.This paper focuses on the optomechanical optimal design lens mounting using glue pads bonding. The main idea of this research study is to obtain an optimal choice of the position of the glue to fix the lenses on the barrel in such a way that we obtain a configuration of the optical assembly performance with less stress.In this paper, an investigation was performed using several methods including (thermo-elastic analysis, the margin of safety and lens distortion analysis). The results show that the position with six contacts glue pads is the best configuration compared to other configurations. This solution can be very helpful for decision-makers and optical engineers during the development phases of space optomechanical systems.     

CFD中统计误差的数值精度分析

在计算流体力学（CFD）的算法研究中经常会对离散误差进行数值精度分析，通常以统计误差的各范数为研究对象，最常用的统计误差范数为L₁范数、L₂范数和L_∞范数，一般认为各范数在数值精度上具有等价性。实际上，由于流场局部存在间断、网格局部不连续或者是在极值点附近采用非线性加权插值等可能使数值方法存在局部降阶问题，导致统计误差各范数所表达的数值精度并不一致。通过详细的理论分析，揭示了统计误差各范数所表达的数值精度之间的关系，并通过相应的数值试验予以验证。研究结果不仅能够指导CFD算法的数值精度验证工作，而且也可为更为复杂流动模拟的数值精度判定提供理论依据。     

A novel range-Doppler imaging algorithm with OFDM radar

Traditional pulse Doppler radar estimates the Doppler frequency by taking advantage of Doppler modulation over different pulses and usually it requires a few pulses to estimate the Doppler frequency. In this paper, a novel range-Doppler imaging algorithm based on single pulse with orthogonal frequency division multiplexing(OFDM) radar is proposed, where the OFDM pulse is composed of phase coded symbols. The Doppler frequency is estimated using one single pulse by utilizing Doppler modulation over different symbols, which remarkably increases the data update rate. Besides, it is shown that the range and Doppler estimations are completely independent and the well-known range-Doppler coupling effect does not exist. The effects of target movement on the performances of the proposed algorithm are also discussed and the results show that the algorithm is not sensitive to velocity. Performances of the proposed algorithm as well as comparisons with other range-Doppler algorithms are demonstrated via simulation experiments.     

机载空空导弹武器系统精度评估方法

研究了用系留飞行数据计算、分析和评价武器系统精度的详细方法,并给出了典型分析实例,通过在机载空空导弹武器系统研制和载机加挂先进空空导弹项目的应用,验证了其正确性和实用性.     

基于光电延时法的激光测距精度测试系统

介绍了一种激光测距精度测试系统,系统采用了光电延时模拟距离的原理,实现了对激光测距机测距范围（500～20 000）m内测距精度的测量。测试系统具有高测量精度、高分辨力、易操作、实用性强的特点。     

A toolpath strategy for improving geometric accuracy in double-sided incremental sheet forming

The double-sided incremental forming (DSIF) improved the process flexibility compared to other incremental sheet forming (ISF) processes. Despite the flexible nature, it faces the challenge of low geometric precision like ISF variants. In this work, two strategies are used to overcome this. First, a novel method is employed to determine the optimal support tool location for improving geometric precision. In this method, the toolpath oriented the tools to each other systematically in the circumferential direction. Besides, it squeezed the sheet by the same amount at the point of interest. The impacts of various support tool positions in the circumferential direction are evaluated for geometric precision. The results demonstrate that the support tool should support the master tool within 10° to its local normal in the circumferential direction to improve the geometric accuracy. Second, a two-stage process reduced the geometric error of the part by incrementally accommodating the springback error by artificially increasing the step size for the second stage. With the optimal support tool position and two-stage DSIF, the geometric precision of the part has improved significantly. The proposed method is compared to the best DSIF toolpath strategies for geometric accuracy, surface roughness, forming time, and sheet thickness fluctuations using grey relational analysis (GRA). It outperforms the other toolpath strategies including single-stage DSIF, accumulative double-sided incremental forming (ADSIF), and two-stage mixed double sided incremental forming (MDSIF). Our approach can improve geometric precision in complex parts by successfully employing the support tool and managing the springback incrementally.     

某型转台内框热力耦合分析

转台内框是决定转台测试精度的重要部件。本文采用有限元方法,计算了内框在同时受到负载热和重力耦合作用下的应力和变形。结果表明,内框在热力耦合的影响下产生的变形量,比单独受热和受力线性叠加后产生的形变量要大。热力耦合分析综合考虑了各误差源对转台精度的影响,可用于指导结构优化设计。     

中华世纪坛旋转圆坛旋转平稳性测试

介绍了两种旋转平稳性的测试方法。角速率均匀性的经纬仪测量法和水平跳动的水平仪测量法,精确度高,简单方便,亦可作为其它相似建筑的旋转平稳性的测试方法。     

GPS频标比对系统的研制

应用GPS技术研制频标比对系统可对野外环境条件下的通信设备快速地进行时间频率校准.本文详细描述了系统中GPS频率标准源以及比相法、时差法频标比对单元的设计方案和软件设计思路,并给出了设计方案中关键技术解决的途径.该系统经校准完全能够满足要求,并在计量技术机构范围中得到应用.     

一种仪器用高准确度MCXO

针对频率计等仪器中使用温补晶振的特殊情况提出并实现了一种软件数据补偿的特殊ＭＣＸＯ。其补偿原理与传统的方式有所不同，它不是对振荡器进行补偿控制，而是根据温度的变化以数据方式不断修改晶体振荡器的频率标称值来达到提高准确度的目的，当该振荡器被用作标准来测量其它信号或用它产生标准时间信号时，都以其准确的频率为基础进行运算和处理。所以，这种ＭＣＸＯ不但远比同类ＭＣＸＯ简单，而且在构成系统中获得的准确度也高得多