利用多传感器信息融合技术实现电子装备的故障诊断

在现代电子装备故障诊断中,依靠单一传感器只能完成简单的故障诊断,难以完成复杂情况下的故障的诊断和定位.多传感器信息融合的方法,可以充分利用多传感器之间的互补信息,并且结合故障的先验知识,采用模糊判决的方法,实现故障的快速准确定位.多传感器信息融合的故障诊断方法为电子装备的故障诊断提供了一种有益的尝试.     

利用BIT技术提高雷达维修性

在现代复杂电子系统中,机内测试(BIT)技术作为提高系统可维修性和可测试性的重要手段,日益得到普遍重视和广泛应用。根据设计原则,BIT系统采用多机分布式结构,故障检测电路和故障检测软件采用通用化设计,故障定位采用基于故障传播有向图的故障定位方法。本文对雷达设备的维修性及状态监测方面进行了探索,主要阐述了机内测试系统的实现结构及其基于故障树算法实现故障定位的原理,介绍了通用故障检测电路的工作原理,总结了设计过程中应注意的问题及相应的解决方法。     

光网络中的分布式故障定位方法

提出一种用于全光网络中的故障定位方法，该方法克服了以往的故障定位方法需要告警上报和传递、故障定位时间长和适用范围有限的缺点，采用单节点分布式故障定位方法，避免了告警信息在节点之间的传递，能够实现快速准确的故障定位，并且适用于任何规模和拓扑结构的网络。     

一种基于故障指示器的配电主站故障定位实现方法

我国配电网线路数量多、分支多、运行方式复杂,在线路发生故障时,故障点的查找费时费力,线路维护人员的工作量大,效率低,线路故障点的准确定位能够帮助维修人员快速排除故障、恢复供电,这对于提高供电可靠性具有重要意义。本文介绍一种基于故障指示器的主站故障定位实现方法,它将故障指示器上传的故障信息进行分析,具有纠错和补漏功能,快速给出故障定位结果通知维修人员。该方法实现起来逻辑简单,成本较低,具有一定的实用性。     

基于功能重构的电路故障修复技术研究

电路故障存在定位和修复比较难的问题,基于功能重构的故障修复技术解决了这一问题.该方法是将测试过程中的响应值和实际电路的响应值进行比较,实现故障的精确定位.确定故障之后采用功能重构的原理对故障电路进行修复,从整体上降低了电路的修复难度.     

基于喘振谱分析的压缩机故障智能检测技术研究

为了实现对压缩机故障的准确诊断和实时检测,保证天然气压缩机的稳定运行,提出一种基于喘振谱分析的压缩机故障智能检测技术.对在故障工况下的天然气压缩机喘振时间序列进行样本数据采集,对采集的样本数据进行故障信号特征提取,采用小波变换方法进行压缩机故障信号的时频分解,运用喘振谱分析方法提取故障特征参量,以提取的故障特征参量为测试样本集,通过故障分类器实现故障智能检测识别.仿真结果表明,采用该方法进行压缩机故障检测的准确检测概率较高,对故障点的定位识别性能较好,实现天然气压缩机故障的智能诊断.     

面向GPU设计的图形流水线故障检测方法研究

现代GPU通常采用超长图形流水线设计,功能单元众多、结构多样复杂,导致GPU在设计过程中故障定位难度大、耗时长、精度低.在深入研究图形流水线工作原理的基础上,提出了一种面向GPU设计的图形流水线故障检测方法.通过对图形流水线分级处理,逐级收集并分析运行状态信息,来达到故障定位的目的.在某款航空军用嵌入式GPU芯片设计过程中采用本方法,大幅提高了故障定位的精确度和速度,使平均定位时间缩短60%以上.     

基于改进Otsu＿Canny算法的光伏组件故障定位研究

为了提高光伏系统在线故障诊断的效率,提出一种基于改进遗传算法的Otsu＿Canny光伏组件故障定位方法。采用此方法可以实现从大面积光伏面板的红外图片中提取故障组件,将该方法与基于图像识别的故障诊断方法相结合能够大大提高光伏组件故障诊断的效率。首先利用改进遗传算法的Otsu算法实现光伏组件故障区域分割,再利用Canny算子实现故障边缘检测,最终完成故障定位。实验结果表明,与传统算法相比,所提算法故障定位快、准确率高,具有较好的实用性和应用价值。     

复杂生物传感网络的节点优化定位模型仿真

根据复杂生物传感器网络节点的定位和数据监测的需要,构建生物传感网络的模型,设计了基于强跟踪滤波的集中式扩维量化融合算法.该算法采用预加重方法补偿节点之间的系统功率衰减,通过动态跟踪信号功率的变化,得到传感器融合中心最终的节点定位状态信息矩阵;通过强跟踪滤波,提高抗干扰能力,实现传感网络节点定位模型改进.结果表明,采用该算法进行复杂生物传感网络节点定位,能有效提高节点定位的准确性,定位误差较小,定位时间较快,稳健性和抗干扰性较好.     

一种基于二叉树的测控设备故障诊断方法

针对传统故障树知识规则存储和诊断推理算法不易实现的问题,提出了一种基于二叉树的故障诊断方法。首先,通过对故障树与二叉树转换规则与方法的分析,直接构建出测控设备故障二叉树集;然后,利用二叉树节点左右编码值来定位该节点的方法,建立故障诊断规则库;最后,采用遍历诊断规则库的搜索算法实现对故障定位。在测控设备中的应用表明,该方法能够方便地建立诊断规则库,准确定位设备故障,可有效提高设备故障诊断效率。     

感应自加热重熔无铅焊料凸台的剪切失效模式

通过两次高频感应重熔制备了Cu焊盘上S n3．5Ag焊料和Sn3．0Ag0．5Cu焊料凸台,并进行了120℃下的老化试验以及老化试件的剪切强度试验,分析了不同老化时间下两种无铅焊料凸台的剪切断裂模式。焊料凸台的剪切载荷-位移曲线的特征以及对焊料凸台剪切断口的扫描电镜形貌分析结果表明,不同老化时间下无铅焊料凸台的剪切断裂表现为塑性、韧性和脆性三种断裂模式。对凸台焊料合金的组织以及界面观察结果表明,随老化时间不断生长的脆性金属间化合物层以及焊料组织粗大是致使断裂失效模式转变的根本原因。     

Location of current carrying failure sites in integrated circuits by magnetic force microscopy at large probe-to-sample separation

In integrated circuit failure analysis excessive current flow is often used to indicate the presence of faulty devices. By imaging the magnetic field produced by current flowing in integrated circuit conductors, these faulty devices can be located. Fault location by magnetic field imaging can be problematic as the devices are often buried under several layers of dielectrics and conductors that are up to several microns thick. In this paper we present a new technique for fault location based on magnetic force imaging of the magnetic field. By subtracting magnetic force images acquired at different probe-to-sample distances, the effects due to background, and probe geometry can be eliminated. We demonstrate that this method is capable of locating current carrying failure sites in model circuits with sub-micrometer uncertainty. We show how the technique can be used to map current paths in the presence of interfering currents on power supply and ground lines.     

Failure analysis case study on a Cu/low-k technology in package: New front-side approach using laser and plasma de-processing

Because of its advantages (reduction of thickness, improvement of the signal delay and of the thermal dissipation…), Cu/low-k technologies are more and more used for RF applications in semiconductor industry. The failure analysis of such devices becomes a new challenge. This paper deals with a failure analysis case study on copper and low-k dielectric structure encapsulated in a plastic package. It shows the limitations of the techniques used in a standard failure analysis flow and presents a new sample preparation combining laser package ablation and specific RIE process for front-side decapsulation. This innovative sample preparation flow has been found mandatory for solving the failure analysis case: it was demonstrated that there was not any defect at the surface of the die and this method enabled the access to an EOS defect located between two metal layers.     

Fault isolation at P/N junction by nanoprober

Precise location of leakage in a P-well/N-well junction has been identified by an AFM (atomic force microscope)-based nanoprober. In order to provide the accurate position of the failure for further analysis, a new method was proposed by combining nanoprobing I–V results on each P-well/N-well contact together with semi-empirical calculation to identify the possible leakage path. Further plan view TEM analysis confirms our result.     

Performance evaluation of soft handoff considering macrodiversity effect in multimedia CDMA systems

The macrodiversity changes the required transmission power to serve a mobile station according to its location. It helps to improve system performance but also causes unexpected call-dropping after handoff. This effect has been neglected when only voice service is provided. But for multimedia traffics which require high data rates, it should be considered. In this paper, we develop a new analytic model of soft handoff considering this effect. Performances have been evaluated with respect to the blocking probability, the handoff failure probability and the region-transition failure probability, using analytic and simulation method. Especially, the region-transition failure probability is a newly introduced performance factor that has been neglected in previous research. Numerical results are compared with previous analytic model to show the effect of macrodiversity on the system performance. The results of this paper can be used for the system management such as determinations of an optimal resource allocation, a cell configuration, and an admission strategy.     

Performance Analysis of Received Signal Strength Fingerprinting Based Distributed Location Estimation System for Indoor WLAN

Location Estimation has become important for many applications of indoor wireless networks. Received Signal Strength (RSS) fingerprinting methods have been widely used for location estimation. Most of the location estimation system suffers with the problem of scalability and unavailability of all the access points at all the location for large site. The accuracy and response time of estimation are critical issues in location estimation system for large sites. In this paper, we have proposed a distributed location estimation method, which divide the location estimation system into subsystems. Our method partitions the input signal space and output location space into clusters on the basis of visibility of access points at various locations of the site area. Each cluster of input signal space together with output location subspace is used to learn the association between RSS fingerprint and their respective location in a subsystem. We have performed experimentation on two RSS dataset, which are gathered on different testbeds, and compared our results with benchmark RADAR method. Experimental results show that our method provide better results in terms of accuracy and response time in comparison to centralized systems, in which a single system is used for large site.     

Compression of the layered depth image

A layered depth image (LDI) is a new popular representation and rendering method for objects with complex geometries. Similar to a two-dimensional (2-D) image, the LDI consists of an array of pixels. However, unlike the 2-D image, an LDI pixel has depth information, and there are multiple layers at a pixel location. We develop a novel LDI compression algorithm that handles the multiple layers and the depth coding. The algorithm records the number of LDI layers at each pixel location, and compresses LDI color and depth components separately. For LDI layer with sparse pixels, the data is aggregated and then encoded. An empirical rate-distortion model is used to optimally allocate bits among different components. Compared with the benchmark compression tools such as JPEG-2000 and MPEG-4, our scheme improves the compression performance significantly.     

基于前转指针的平滑主动位置恢复方案

提出了一种基于前转指针的平滑主动位置恢复方案,以位置数据库的处理能力和有线信令消耗,换取无线资源的节省。无需终端的周期性位置更新操作,即可使移动通信系统获得对位置数据库的容错能力。同时,在故障期内采用前转位置指针,使移动用户感知不到HLR故障的存在,具有持续的出呼叫能力。     

宽光谱膜厚监控系统的评价函数修正技术

基于评价函数的宽光谱膜厚监控系统,由于实测光谱曲线和理论光谱曲线相背离,使得评价函数发散,监控失败。利用实测的膜层透射率光谱曲线,对于已镀层,利用模拟退火算法实时拟合其实际的光学常数,据此修正目标透射率曲线,并补偿吸收的影响,重新设计膜层数及预镀层厚度,获得新的评价函数,如此对评价函数进行逐层修正。实验结果表明,薄膜厚度监控误差可以达到10-2以下,精度完全可以满足实际要求。     

一种新的连铸中间包钢水液位测量方法

连铸中间包的钢水的液位测量环境恶劣和钢水上层覆盖保护渣层而导致钢水液位测量困难、测量准确度不高.针对此现状,本文提出了一种基于温场信息,利用计算机视觉测量实现的钢水液位测量方法.此方法通过对中间包内的空气层、保护渣、钢水层温场分析和获取,确定空气层-保护渣层和保护渣层 钢水层的温度梯度分界面位置,从而得到中间包内钢水液位.测量方法应用到现场,统计得到测量平均绝对误差为3.2mm,最大误差为5.2mm,最小达到0.3mm,本文液位测量方法准确可靠,具有良好的应用前景.