极紫外平场光栅光谱仪的研制和性能测试

研制了一台高分辨率极紫外光谱仪,用于磁约束等离子体诊断。采用一块具有平场特性的全息球面变线距光栅作为分光元件,光栅公称线密度为1 200 lines·mm-1,掠入射角为3°。一台可深度制冷、背照式面阵CCD作为光谱探测器,用机械快门控制曝光时间。通过CCD在光谱聚焦面的移动,可以记录的光谱范围为5～50 nm。用Penning放电光源测试了光谱仪的性能; 利用光源的标准谱线,进行了波长标定,波长精度为0.003 nm,并计算出系统各参数的实际值;当入缝宽度设置为30 μm时,在20 nm附近,光谱分辨率达0.015 nm,达到设计指标。     

无人机健康诊断知识库建立研究

针对无人机健康诊断系统的设计,研究了健康诊断专家知识库的建立方法。介绍了基于规则的专家知识库的含义及其对无人机设计的要求,阐述了故障树与故障模式判据表的形成方法。故障树分析基于故障因果逻辑,逐层找出故障事件的原因,保证专家知识逻辑上的完备性。故障模式判据表将抽象的专家知识具体化为多个能够在工程上应用的要素。提出了一种故障树分析与故障判据规则相结合的建立健康诊断专家知识库的方法。从某型大气数据系统的组成及原理出发,以大气数据系统真空速失效为顶事件,构造了故障树和故障模式判据表。结果表明,结合故障树和故障模式判据表格构造的专家知识库清晰、简洁,具有很高的工程实用价值,能够应用于无人机健康诊断系统的设计。     

基于Linux的薄壁管材冲孔自动化生产线设计

为了开发一种结构简单、控制灵活的冲压自动化装置,文中简述了一种基于Linux下的冲孔自动化生产线,用于薄壁管材的冲孔。设计了以ARM为主控制器,CPLD为协处理器的方式来作为整个生产系统的控制核心。建立了气缸驱动系统和冲压机械手,机械手通过伺服电机的驱动完成取料和旋转,在与冲床的相互配合下完成冲孔要求。构造了生产线系统的故障树,利用定量分析结合定性分析的方式对故障进行分析,采用电容式触摸屏通过界面向操作人员发送故障提示,大大减少了设备停机时间。实验结果表明该系统完全能满足生产要求,稳定可靠,操作便捷,响应速度快。     

Stochastic resonance characteristic analysis of new potential function under Levy noise and bearing fault detection

Based on the output saturation of classcial bistable stochastic resonance (CBSR), a new type of piecewise nonlinear bistable stochastic resonance (PNBSR) system is constructed. The mean signal-to-noise ratio gain is regarded as an index to measure the stochastic resonance phenomenon. The laws for the resonant output of piecewise nonlinear bistable system governed by l, c, a, b and D of Levy noise are explored under different characteristic index α and symmetry parameter β of Levy noise. The results show that the output of PNBSR system has increased 4?dB by comparing with the output signal-to-noise ratio of CBSR system. And the stochastic resonance phenomenon can be induced by adjusting the piecewise nonlinear system's parameters under any α or β of Levy noise. The interval of the parameters of system which induces good stochastic resonance is roughly the same. And the output signal waveform of resonance is very similar to the input signal waveform, which has some reference value for the signal recovery. Moreover, we can find the good stochastic resonance interval of the system parameters do not change with D of Levy noise under the different noise intensity D of Levy noise. On the basis of this, adjusting the intensity amplification factor D of Levy noise, which induces good stochastic resonance, and the interval does not change with α or β. At last, the piecewise nonlinear bistable system is applied to detect bearing fault signals, which achieves better performance compared with the classical bistable system.     

基于主元分析与动态时间弯曲的故障诊断方法及应用研究

轴承是工程实际中常用而又极易损坏的部件,特别是对其早期微弱响应的辨识,具有重要的社会价值和意义。为提高运转轴承的安全可靠性和可维护性,提出了基于主元分析与动态时间弯曲距离的故障诊断方法,它可以准确对早期微弱动态响应辨识、诊断。该方法首先将典型故障样本信号与待测信号小波去噪并EMD分解,并对若干固有模态分量主元分析求取主元,然后对主元分量进行分析,获得相关特征值组成特征向量,计算待测信号与已知故障样本信号特征向量的弯曲距离,弯曲距离越小表明两信号越相似,从而辨识故障。此外,还可将其应用于转子、碰磨、齿轮故障诊断中,工程应用实例表明该方法可以准确故障分类,高效故障诊断。     

基于GIS和OTDR的光纤智能监控系统研究

为了提高光纤故障处置效率,设计了一种基于GIS和OTDR的光纤智能监控系统。介绍了系统的总体技术架构和软件功能框架。采用小波分析技术,提取OTDR曲线中的事件信息,找出故障点位置。将故障点的光纤长度数据转换为经纬度数据,并结合光缆拓扑结构和GIS系统,将故障点在电子地图上实时显示并告警。经过系统测试,结果表明：系统的OTDR损耗分辨率达到0.01dB,动态范围为34dB~45dB,监测响应时间为5ms;故障定位误差小于10米,告警时间为2ms,完全满足光缆应急处置要求。     

高可靠分布式容错计算机架构的研究

分布式系统因其具有分散安装、可靠性高、扩展性好、维修成本低、健壮、安全等诸多优点,国内外相继开展分布式计算机高可靠性技术的研究。本文提出了高可靠分布式容错计算机的构架设计思路,并对TTE总线的选用进行了分析论证,重点描述了成员一致性保证和余度同步等关键技术。     

利用相干渡越辐射测量电子束团长度的分析与计算

利用相干渡越辐射(CTR)测量短和超短电子束团长度是国际上束测领域新发展的频域测量技术.文中理论分析和数值计算了北京自由电子激光装置的皮秒级的射频电子束团序列产生的CTR,当辐射波长在长于束长(4ps)时,渡越辐射发生相干增强效应;与非相干渡越辐射相比,当λ≥2πσz时,增强的倍数约等于束团中粒子的数目(10⁸);CTR从亚毫米波到毫米波段呈宽带连续谱特性;渡越辐射能量主要集中在轴线附近,宏脉冲辐射能量高达几毫焦.设计采用偏振型束团长度测量系统,利用CTR自相关技术,实验测量该束团序列的纵向长度,并藉助傅里叶变换光谱法,推求束团电子分布.     

Pattern recognition system for the discrimination of multiple sclerosis from cerebral microangiopathy lesions based on texture analysis of magnetic resonance images

In this study, a pattern recognition system has been developed for the discrimination of multiple sclerosis (MS) from cerebral microangiopathy (CM) lesions based on computer-assisted texture analysis of magnetic resonance images. Twenty-three textural features were calculated from MS and CM regions of interest, delineated by experienced radiologists on fluid attenuated inversion recovery images and obtained from 11 patients diagnosed with clinically definite MS and from 18 patients diagnosed with clinically definite CM. The probabilistic neural network classifier was used to construct the proposed pattern recognition system and the generalization of the system to unseen data was evaluated using an external cross validation process. According to the findings of the present study, statistically significant differences exist in the values of the textural features between CM and MS: MS regions were darker, of higher contrast, less homogeneous and rougher as compared to CM.     

红外光谱技术在医学中的应用

系统回顾了过去50余年中红外光谱技术的发展创新及在生物医学领域中的研究应用。傅里叶变换红外光谱技术已从对单个细胞水平结构构成与形态的研究进展到组织水平。现代红外光谱技术联合成熟的模式识别技术与组织微阵列技术,为平行大规模测定分子结构提供了可能。此外,红外光谱技术的临床应用为良恶性肿瘤的判别提供了可信的参考依据,并可准确判别甲状腺、乳腺、胃肠道及腮腺等组织的良恶性,具有极广泛的应用前景。