Stochastic resonance in an asymmetric bistable system driven by multiplicative and additive Gaussian noise and its application in bearing fault detection

The phenomenon of stochastic resonance (SR) in a new asymmetric bistable model is investigated. Firstly, a new asymmetric bistable model with an asymmetric term is proposed based on traditional bistable model and the influence of system parameters on the asymmetric bistable potential function is studied. Secondly, the signal-to-noise ratio (SNR) as the index of evaluating the model are researched. Thirdly, Applying the two-state theory and the adiabatic approximation theory, the analytical expressions of SNR is derived for the asymmetric bistable system driven by a periodic signal, unrelated multiplicative and additive Gaussian noise. Finally, the asymmetric bistable stochastic resonance (ABSR) is applied to the bearing fault detection and compared with classical bistable stochastic resonance (CBSR) and classical tri-stable stochastic resonance (CTSR). The numerical computations results show that:(1) the curve of SNR as a function of the additive Gaussian noise and multiplicative Gaussian noise first increased and then decreased with the different influence of the parameters a, b, r and A; This demonstrates that the phenomenon of SR can be induced by system parameters; (2) by parameter compensation method, the ABSR performs better in bearing fault detection than the CBSR and CTSR with merits of higher output SNR, better anti-noise and frequency response capability.     

光纤激光器故障模式分析

为满足实际工程、生产应用中专业及非专业人员对故障光纤激光器快速修理、修复的需要,研究了一种能够实现快速故障模式及故障原因分析系统。首先,采集实际使用与实验中损坏激光器的故障模式与故障原因记录为数据样本。接着,利用故障树与故障模式影响及危害性分析模型建立光纤激光器扩展故障树,即构建起故障模式与故障原因的对应关系。然后,利用贝叶斯网络分析并得出各故障模式与故障原因的先验概率与后验概率计算方法,再使用Python语言编写交互式窗口,并完成对数据库数据的调用与相应概率计算。最后,通过交互式界面输出当前故障对应的可能故障原因及发生概率,从而实现对光纤激光器故障的快速分析。程序模拟耗时小于1 s,模拟结果与统计结果相吻合,基本满足指导相关人员对故障快速排查并修理的要求。     

塔北哈拉哈塘地区走滑断裂分段特征及其与油气成藏的关系

塔北哈拉哈塘地区奥陶系碳酸盐岩油气资源丰富,走滑断裂是该地区油气成藏最主要的控制因素.基于最新的高精度三维地震资料,借助最大波谷振幅属性提取的物探手段,结合走滑断裂的理论模型,探讨了哈拉哈塘地区走滑断裂的分段特征及其与油气成藏的关系.研究表明,哈拉哈塘地区主干走滑断裂平面不是连续不断的,而是由一系列雁列排布的R剪切断裂组成,具有明显的分段性：断阶带（overlap）发育成的P剪切断裂与R剪切整体构成辫状的构造样式;而在R剪切末端,派生出R'剪切、T剪切等次级断裂,组成马尾或羽状构造.不同区带具有不同的油气成藏条件：断阶带,受挤压应力控制发育局部背斜,为油气运移的长期指向区,而背斜翼部沿断层发育的串珠储集体为油气聚集提供了有效空间;走滑断裂末端的马尾构造区,断裂数量多、地势低,发育规模储集体,但油气易沿断裂向高处运移,油气保存条件较差.     

门限Byzantine quorum系统及其在 分布式存储中的应用

针对纠删编码和门限方案在分布式存储中的应用,提出门限Byzantine quorum系统(TBQS)的概念.该系统与数据分离算法相结合,可以构造可靠性较强的存储系统,当故障服务器个数不超过服务器总数的1/4时,利用TBQS设计存储策略可以实现容错和无间断服务.讨论了TBQS的存在性,构造了两类TBQS并对其效率进行分析,在此基础上设计了基于TBQS的分布式读写协议.     

Controllability of Static CMOS Circuits for Timing Characterization

Timing violations, also known as delay faults, are a major source of defective silicon in modern Integrated Circuits (ICs), designed in Deep Sub-micron (DSM) technologies, making it imperative to perform delay fault testing in these ICs. However, DSM ICs, also suffer from limited controllability and observability, which impedes easy and efficient testing for such ICs. In this paper, we present a novel Design for Testability (DFT) scheme to enhance controllability for delay fault testing. Existing DFT techniques for delay fault testing either have very high overhead, or increase the complexity of test generation significantly. The DFT technique presented in this paper, exploits the characteristics of CMOS circuit family and reduces the problem of delay fault testing of scan based sequential static CMOS circuits to delay fault testing of combinational circuits with complete access to all inputs. The scheme has low overhead, and also provides significant reduction in power dissipation during scan operation.

一种基于非并行BIT的测试性模型

通过条件测试解决了在LRU间增加非并行BIT不满足信息流模型测试的一般定义的问题,同时解决了信息流反馈的问题,提高了故障隔离率.提出了基于信息流模型的集中一分布式BIT体系结构,建立了基于该体系结构的系统级BIT测试模型.通过对BIT测试模型的改进,建立了边界扫描测试模型.     

水电仿真系统中厂用变压器模糊故障综合诊断

在总结领域专家经验基础上,采用模糊诊断方法,列出了仿真系统中变压器的征兆集和故障集,并根据征兆集和故障集的相互关系构建模糊诊断矩阵;通过模糊关系矩阵运算,提出最大隶属度原则判断变压器故障原因。测试和评价结果表明模糊诊断在仿真系统中的有效性和可行性。     

基于闭环集成运放的模拟电路模块级软故障诊断

基于斜率故障模型,提出了一种诊断模拟电路中基于闭环集成运算放大器的模块级软故障的字典法.在由闭环运放组成的模拟电路中,通过对电路以闭环运放及与其输入直接相连的元件看作一个整体划分模块,对各个模块中的任一元件或进行宏模型替代之后的运放等效电路,利用电路中的两节点电压增量计算出的斜率作为统一故障特征,建立故障字典,实现电路中相应模块包含的运放和所有元件的软故障诊断.给出了运放的等效宏模型和模块级软故障的诊断步骤,并用仿真实例证明了该诊断方法的有效性.     

数字电视解调芯片的可测试性设计与优化

介绍了VLSI芯片的测试技术及故障模型,针对一款数字电视接收系统解调芯片,从设计中不同的阶段分析了集成电路的可测试性设计及其优化,解决了由于集成大量存储器引起的测试覆盖率低的问题,完成了该芯片满足时序要求的可测试性设计及优化过程,达到了流片要求.     

基于故障映射的并行故障仿真方法

提出了基于故障映射的4值并行故障仿真方法.这一方法首先把电路划分成无扇出区域和扇出茎区域,然后将非扇出茎故障映射为扇出茎故障,减少了需要显式并行仿真的故障数目,提高了仿真器的性能.实验结果验证了文中方法的有效性.