基于故障树和神经网络的飞机电源系统故障诊断研究

介绍了基于故障树模型的故障诊断技术和基于神经网络的故障诊断技术，提出了基于故障树和神经网络的集成故障诊断思想。在此基础上，以交流发电机旋转整流器二极管开路故障为例进行了实例分析，说明了故障树和神经网络集成故障诊断技术对此故障的诊断，结果表明该方法用于解决此类问题是有效的。     

基于模糊神经网络的执行器故障诊断

针对神经网络在故障诊断中的局限性,提出了一种将模糊理论与BP神经网络结合的故障诊断方法,使其应用到执行器故障诊断中.通过和BP神经网络学习算法对执行器故障诊断的结果比较来证明模糊神经网络算法的优越性.首先介绍执行器常见故障;其次对故障征兆进行模糊化预处理,获得了神经网络训练样本,最后应用Matlab软件进行了系统仿真.仿真结果表明:该方法收敛速度快、诊断精度高、自适应性强,能够有效地诊断执行器故障.     

SOM神经网络在风力发电机组故障诊断中的应用

风力发电正在电力行业中占有越来越重要的位置。然而因为所处的环境条件恶劣,风力发电机经常容易发生故障。传统的状态监测与故障诊断方法较为费时费力,又因为无法采集到所有的故障信息,所以BP神经网络无法做出正确诊断。因此,将SOM神经网络应用于风力发电机组的振动故障诊断中。用正常运行的样本数据对网络进行训练,根据检测样本输出神经元在输出层的位置对是否发生故障进行判断。经实例分析证明,该方法可对风电机组的故障进行有效诊断。     

基于改进ALIF与FA-BP的滚动轴承故障诊断

针对滚动轴承的故障信号存在大量噪声信号和滚动轴承故障的准确诊断等问题，提出一种基于改进自适应迭代滤波算法与萤火虫算法优化BP神经网络相结合的故障诊断新方法。首先采用自适应迭代滤波算法对故障信号进行分解得到若干个内禀模态函数，再进行奇异值分解，绘制差分谱曲线并选择重构信号，对其进行二次降噪；然后通过萤火虫算法寻找BP神经网络的最佳参数，建立FA-BP故障诊断模型，提取降噪后的内禀模态函数中心频率形成特征矩阵，输入故障诊断模型；最后应用于美国凯斯西储大学的轴承数据进行检测，准确率达99.4%，诊断时间为3.18 s。该方法与BP神经网络、萤火虫算法网络、遗传算法网络、遗传算法优化BP神经网络的诊断模型相比，大大提高了诊断效率并具有较高准确率。     

基于BP神经网络的电控发动机故障诊断

针对汽车发动机电控系统结构的复杂性,提出用BP神经网络进行故障诊断的方法。以北京现代05款途胜G4GC型发动机电控系统为实验,并对其进行故障设置,采集发动机故障数据流,运用BP神经网络构建诊断模型,并且改变BP训练方法。诊断结果表明用BP神经网络诊断发动机电控系统故障是行之有效的,具有较好的应用前景。     

基于BP神经网络的某型飞机火控系统故障诊断

根据某型飞机火控系统的特点,给出了BP神经网络数学模型及其学习算法,在此基础上以某型飞机火控系统作为为被诊断对象,运用BP神经网络数学模型及其学习算法对其进行故障诊断。诊断结果表明BP神经网络不仅能识别出样本自身的故障,而且能准确诊断出样本以外数据故障,提高某型飞机火控系统一线维修保障效率。     

模拟数字电路故障诊断新方法

利用小波变换与神经网络相结合的方法,采用能量分布特征提取方法和改进BP算法,给出了一种基于小波变换和BP神经网络相结合的模拟电路故障诊断方法.用正弦信号仿真模拟电路,应用小波变换对模拟电路的采样信号进行多尺度分解,再进行能量分布特征提取,然后利用神经网络对各种状态下的特征向量进行分类识别,实现模拟电路故障诊断.在用神经网络诊断模拟电路的基础上,进行了将神经网络用于数字电路单故障诊断的研究.对两者的实例电路仿真结果表明,神经网络可以有效、方便地实现电路的故障检测和定位,准确率高,为故障诊断的研究提供了一种新思路.     

一种基于神经网络的模拟电路故障诊断方法

模拟电路故障诊断一直是一项富有挑战性的研究课题。文章在简要介绍BP神经网络基本原理的基础上,以差分放大电路为例,设计并实现了基于BP算法的模拟电路故障诊断方法,建立了模拟电路故障诊断BP神经网络模型。实验表明,该模型的辨识精度高,能实现对模拟电路故障的正确诊断。     

一种融合FTA与BAM的故障诊断方法

在研究故障树分析(FE气)和双向联想记忆(BAM)神经网络在故障诊断中应用的基础上,提出了一种融合FTA和BAM的故障诊断方法.故障树存贮了系统关于顶事件发生的全部知识,利用FTA得到系统所有的故障模式,进而归纳出BAM的学习样本,即故障树中故障现象(监测点状态组合)和底事件发生与否之间的对应.RAM通过联想记忆矩阵并行联想,得到诊断结果,扩展综合故障诊断能力.仿真结果表明该方法用于解决此类问题是有效的.     

故障树分析方法在脉冲雷达故障检测中的应用

故障树分析方法是一种实用的故障分析方法,文章通过对某单脉冲雷达建立故障树模型,进行定性、定量分析计算。利用构建故障树来进行无线电测量设备故障诊断分析,不仅可以方便推理机构寻找潜在故障或进行故障诊断,而且可以进一步预测未来系统故障发生的概率,便于测量设备故障的检测与定位。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.