Modeling and Simulation of Pipeline Security Monitoring System Based on Line-Structure Sagnac Interferometer with 3×3Coupler

The third damage action,human disruption behavior,is one of the major threats to pipeline operation.It is necessary to monitor and locate the perturbation behavior that may threat pipeline safety in real-time.Therefore,a new pipeline security monitoring system is designed by using line-structure Sagnac optic fiber interferemeter with the characteristic of 3×3coupler that can modulate the phase of optic signal,with no need for phase modulation and demodulation.The optic structure of the new system is simplified,the signal processing accuracy is improved,and the polarization effect is reduced.The working principle of the monitoring in ideal condition is described,the phase demodulation is analyzed and the location of the possible damage action point is formulated.By using simulink,the optic signal propagation and interference is simulated and interference signals in different frequencies are obtained.The results validate the feasibility of the monitoring system and indicate that the low frequency signal less than 1kHz resulting from the human damage action can be detected.The disturbance set at 10 km can be located by calculating the demodulation signal accurately over a long monitoring distance.     

基于可诊断性约束的测点优化配置研究

为提高卫星的安全性和可靠性,适应在设计阶段对故障诊断进行考虑的需求,以动量轮为例,将故障可诊断性作为优化目标,提出基于DM分解技术的测点优化配置方法,并给出故障可诊断性评价的相关定义.分析动量轮模型和故障,建立动量轮的结构模型;采用DM技术对动量轮的结构模型进行分解,并分析动量轮模型的解析冗余关系;在对各故障的可检测性和可分离性进行分析的基础上,根据结构模型的偏序关系,获得使故障具有可检测性和可分离性的最小传感器集合;给出故障可诊断性评价的定义,并针对两种传感器配置情况,进行可诊断性分析.本文所提方法为设计阶段开展故障诊断的研究提供了借鉴和参考.     

对中国高模量碳纤维应用中工艺性能问题的分析

文章简述了航天器结构对高模量碳纤维需求,对中国高模量碳纤维品质稳定性、工艺稳定性等内容进行了简要评述,着重对中国高模量碳纤维工艺性能做了分析,并对加强中国高模量碳纤维批生产提出了建议.     

玻璃纤维缠绕壳体在固体火箭发动机一二级上的应用研究

分析了国内固体火箭发动机壳体的研究、生产现状,指出国内导弹第一、二级发动机壳体采用纤维缠绕壳体取代钢壳体已成为必然趋势。通过对国内碳纤维研究、应用现状及碳纤维缠绕壳体与玻璃纤维缠绕壳体性/价比分析,提出就国内对于性能要求不是很高的发动机,采用玻璃纤维缠绕壳体比采用碳纤维缠绕壳体更符合我国目前的技术现状。     

TDS600系列数字示波器自动验收系统

ＴＤＳ６００系列数字示波器自动验收系统，采用人机对话的形式，改变了以往的手动操作验收。以ＲＩＣ３８６计算机为中心，以信号源如：ＳＧ５０３正弦波发生器等为标准，通过ＧＰ－１Ｂ接口总线来编程控制数字示波器，并配以打印机及绘图仪打印结果和波形，对示波器各项功能进行验收，检查仪器的各项指标是否在给定极限范围之内。初学者可根据屏幕上的提示，一步步执行，便可自动进行验收，查看结果。     

炭纤维织物对炭／炭复合材料韧性的影响

探讨了炭／炭复合材料中炭纤维增强织物形式及处理方式对其韧性的影响，并通过材料微观结构及数据的分析得出，经处理的炭／炭复合材料的弯曲强度和破坏挠度分别经同类材料提高５０％和８０％。     

Numerical Prediction of Moduli of 3-D and 4-step Braided Composites

对三维四向编织复合材料的参数化建模技术进行了研究 ,提出了一种“米”字型枝状体胞的计算模型 ,较为真实地模拟了该材料的细观结构 ;在此基础上讨论了相应的边界条件和约束条件并应用有限元方法计算了该材料的纵向、横向弹性模量 .通过与实验结果的对比可见 ,计算结果的预报精度较好     

Technology of Modeling for Shape Memory Alloy Reinforced Composites

在对形状记忆合金增强复合材料层合板进行应力、应变和温度关系实验的基础上 ,建立了形状记忆合金增强复合材料四边形和三角形板单元模型 ,并推导了相应的有限元公式 .在此基础上编制了能够进行静态和动态分析的有限元程序 ,并利用该程序对形状记忆合金增强复合材料悬臂梁进行了分析 ,结果是令人满意的 .随着对形状记忆合金研究的进一步发展 ,这种材料必将在智能材料和结构设计中发挥越来越重要的作用 .     

A comparative study of decision tree,random forest,and convolutional neural network for spread-F identification

Ionospheric spread-F (SF) is a commonly observed phenomenon of electron density perturbation in the F-layer. The ionospheric irregularities structure has an adverse effect on the propagation of electromagnetic waves in the ionosphere. The automatic identification of ionospheric spread-F and statistical study of the formation of spread-F are of great significance to the study of the physical mechanism of ionospheric inhomogeneity and for prediction of ionospheric irregularities. In this paper, we describe and implement three automatic identification methods of spread-F based on machine learning: decision tree, random forest, and convolutional neural network (CNN). The performance of these automatic identification methods was verified using a large set of test data. Results show that the accuracy of all three methods on identifying ionograms with spread-F exceeded 90%. After comparing the results of the three methods, we found that the decision tree method was the simplest and with the structure easiest to be understood, and it required the shortest interpretation time. In terms of the identification results, the random forest method provided better results than the decision tree method, and the CNN method was the best at accurately identifying ionograms with spread-F.     

陀螺寿命试验计算机监测设备

介绍了陀螺寿命试验计算机监测设备的设计方案。此监测设备的研制目的是为了用于在长期、连续工作条件下，自动监控多个单自由度陀螺的运转情况，完成寿命试验。在进行设备可靠性分析的基础上，给出了其硬件实现。