微处理机应用系统容错设计之实例分析——温控仪容错设计

在微处理机应用系统容错设计理论的基础上,采用了过程通道、 Ｒ Ａ Ｍ 的备用容错以及系统恢复和重入技术,对温控仪容错进行了设计．     

自身免疫性肝病自身抗体应用进展

自身免疫性肝病(AILD)是一种由自身免疫反应引起的慢性肝胆系统损伤性疾病,目前尚无根治该疾病的有效措施,早期诊断及治疗对该疾病发展及预后至关重要.自身抗体检测技术的不断提高对AILD诊断及鉴别诊断有重要价值,本文阐述了自身免疫性肝病相关自身抗体的临床应用进展.     

Ho∞-based fault detection for nonlinear networked systems with random packet dropout and probabilistic interval delay

The fault detection problem for the nonlinear networked control system (NCS) with packet dropout and delay is investigated.A nonlinear stochastic system model is proposed to account for the NCS with random packet dropout and networkinduced non-uniformly distributed time-varying delay in both from sensor to controller (S/C) and from controller to actuator (C/A).Based on the obtained NCS model,employing an observer-based fault detection filter as the residual generator,the addressed fault detection problem is converted into an auxiliary nonlinear H∞ control problem.Then,with the help of Lyapunov functional approach,a sufficient condition for the desired fault detection filter is constructed in terms of certain linear matrix inequalities,which depend on not only the delay interval but also the delay interval occurrence rate and successful packet communication rate.Especially,a trade-off phenomenon between the maximum allowable delay bound and successful data packet transmission rate is found,which is typically resulted from the limited bandwidth of communication networks.The effectiveness of the proposed method is demonstrated by a simulation example.     

基于结构自适应模糊神经网络的前列腺癌诊断方法

前列腺癌是近年来严重危害男性健康的疾病.利用模糊神经网络方法可以实现前列腺癌诊断,并将诊断模型表示为模糊规则集合.针对模糊神经网络所提取规则解释性差的问题,提出结构自适应模糊神经网络方法,通过改进损失函数,在训练中控制相似隶属度函数的合并,实现模糊神经网络模型结构自适应调整,减少模糊规则数量,在保证诊断准确性情况下,提取出容易理解的可解释性规则.同时该方法在模型的训练过程中引入粒子群优化(PSO)算法进行结构和参数学习,有效减少计算量,提高训练效率.最后,使用临床医学科学数据中心提供的前列腺疾病检查数据进行数值实验,验证了所提出方法在前列腺癌诊断和可解释性规则提取中的有效性.     

具有混合执行器故障的多智能体分布式有限时间自适应协同容错控制

针对多智能体编队系统执行器发生故障时,所引起的参数不确定以及系统瞬态不稳定问题,本文采用径向基函数神经网络(radial basis function neural networks, RBFNNs)对不确定参数(未知函数)进行估计。同时,基于反推技术设计出合理的自适应容错控制器,并通过有限时间理论保证系统实现瞬态稳定。首先,本文采用10个智能体作为被控对象,基于有向通讯拓扑结构理论,构建了非线性多智能体系统模型。其次,基于RBFNNs逼近特性,采用反推技术与动态面技术相结合,设计出合理的容错控制器,补偿多智能体中出现的未知非线性执行器故障,并采用有限时间理论解决系统瞬态不稳定问题。接着,基于Lyapunov稳定性理论分析了控制器的稳定性和快速收敛性。最后,通过两种算例对比,验证了所设计的控制器性能优于传统的反推技术,为工程实践提供了一种有效的研究思路。     

H_∞-based fault detection for nonlinear networked systems with random packet dropout and probabilistic interval delay

The fault detection problem for the nonlinear networked control system(NCS) with packet dropout and delay is investigated.A nonlinear stochastic system model is proposed to account for the NCS with random packet dropout and networkinduced non-uniformly distributed time-varying delay in both from sensor to controller(S/C) and from controller to actuator(C/A).Based on the obtained NCS model,employing an observer-based fault detection filter as the residual generator,the addressed fault detection problem is converted into an auxiliary nonlinear H∞ control problem.Then,with the help of Lyapunov functional approach,a sufficient condition for the desired fault detection filter is constructed in terms of certain linear matrix inequalities,which depend on not only the delay interval but also the delay interval occurrence rate and successful packet communication rate.Especially,a trade-off phenomenon between the maximum allowable delay bound and successful data packet transmission rate is found,which is typically resulted from the limited bandwidth of communication networks.The effectiveness of the proposed method is demonstrated by a simulation example.     

列车运行监控记录装置故障诊断系统的研究

概括分析了基于故障树分析的列车运行监控记录装置故障诊断系统的特点及存在的问题,并在此基础上,提出了采用双向联想记忆神经网络的故障诊断系统方案。简要介绍了双向联想记忆神经网络故障诊断系统的系统结构、软件系统功能及诊断流程,并以主机无显示故障为例,详细描述了故障诊断模型、M矩阵的建立、推理过程、解释机制的构建原理。最后还概括分析了该系统的优越性,并点出了系统在技术实现中存在的主要问题。     

实现冠心病普查系统GISCAD的进化模型

一般说来,专家系统的开发是一个知识获取的过程。本文首先介绍了我们开发的一个冠心病普查系统,并讨论了知识获取和系统进化等问题,说明了用于开发冠心病普查系统的进化模型。     

基于粗糙决策模型和蚁群算法的故障诊断

粗糙集理论是一种新型的处理模糊和不确定知识的数学工具,它能在保持信息系统分类能力不变的前提下,有效地进行知识约简;决策树算法可对约简后的决策表进行规则提取,有着直观、能定量分析的优点.提出一种变化趋势关联度来评价条件属性的重要性,建立粗糙决策树故障诊断模型,并在诊断推理中引入一种新的人工智能方法——蚁群算法,来确定决策树的最优检测次序.将其应用于工业精对苯二甲酸(purified terephthalic acid,PTA)生产过程中的对二甲苯氧化反应温度的诊断结果表明了提出方法的有效性.     

基于Park-HHT的故障特征提取方法

针对三相对称系统,提出了一种新的故障特征提取方法。该方法首先将系统输出信号进行Park变换,之后进行希尔伯特-黄变换(Hilbert-Huang transform, HHT),从HHT的本征模态函数中选取低频分量,提取信号幅度作为故障特征值。该方法兼具Park变换和HHT的优点,在降低变量维度的同时提高了故障分辨率,并且具有较强的抗噪声能力。最后,在三相逆变电路中进行了仿真实验,根据特征向量间距离分布对不同方法的提取效果进行评价,验证了所提方法的有效性。