可远程支持的航空活塞发动机故障诊断专家系统研究

通用航空存在布局分散、企业机队小及维修技术力量薄弱等特点.使通用航空飞机排故困难;为解决这种情况,对基于故障树和神经网络的航空活塞发动机故障诊断技术进行了研究,构建了基于故障树和神经网络结合,辅以远程专家视频会诊的航空活塞发动机故障诊断专家系统,并给出了故障知识库的构建和管理方法,三种故障诊断模型的推理机制和融合方法;利用收集的航空活塞发动机故障数据对神经网络故障诊断方法进行了验证.有效地诊断出航空活塞发动机的故障.     

基于DFT的飞机电源网络化故障诊断方法

针对目前飞机恒速恒频交流(CSCF-AC)电源系统故障诊断方法中存在的虚警率高、信息不能共享等问题,提出一种基于动态故障树(DFT)的CSCF-AC电源系统网络化故障诊断方法。通过在普通布尔算子中引入BEFORE算子,对CSCF-AC电源系统动态故障树进行定性分析,得到系统的失效模式,在此基础上建立一个包括机内自检、地面诊断和远程专家诊断在内具有三层结构的网络化故障诊断系统。实验结果表明,该方法有效可靠,具有一定的工程实用性。     

基于动态贝叶斯网络的机载电子设备故障诊断

针对目前机载电子设备故障诊断过程中诊断效率低以及采用传统动态故障树马尔科夫链分析方法存在系统状态空间爆炸的问题,提出了一种基于动态贝叶斯网络的故障树故障诊断方案;设计首先将基于零压缩二元决策图的动态故障树定性分析和贝叶斯网络的定量推理相结合获得系统最小割集,然后以集成传感器信息更新系统的部件诊断重要度和最小割集,最后综合考虑系统部件诊断重要度和最小割集设计了系统的故障诊断决策算法,得到故障诊断决策树;以机载光电雷达设备的故障诊断为例,通过对比有无证据条件下系统故障诊断中最小割集以及其诊断重要度,证明了此方案能够准确、快速地诊断出系统具体的故障原因,节省了诊断成本。     

基于Multi-agent的飞机智能故障诊断与监控系统设计

在对飞机故障进行分析的基础上,以Agent为基本单元,建立了飞机智能故障诊断模型,并对诊断任务的分解、飞机智能诊断与监控系统的结构、智能诊断与监控功能的实现方法等进行了分析和研究,设计了飞机故障诊断与监控系统仿真实验方案,对实验准备,实验过程进行了详细的介绍;仿真实验结果表明,基于智能Agent的飞机故障诊断与监控系统,提高了诊断效率及诊断结果的准确性,增加了诊断系统的灵活性和快速性及对故障的监控能力.     

某型飞机电源故障诊断专家系统设计与实现

为了准确、快速地对飞机电源系统故障进行诊断和排除,在分析某型飞机电源系统的失效模式和故障机理的基础上,建立故障树,采用基于规则的故障树分析技术对故障模型进行分析,引入正向推理和反向推理两种推理机制,研究了基于数据库技术的知识库的构建方法,设计某型飞机电源故障诊断专家系统。结果表明,该故障诊断系统的推理结果符合实际情况,提高了飞机电源系统故障诊断的智能化水平。     

改进的故障树模糊诊断方法及其应用

针对故障诊断中存在的重复诊断问题和不确定性因素,提出了一种基于故障树的模糊故障诊断改进方法。该方法将模糊理论融入到故障诊断中,综合考虑了系统故障树的最小割集和基本组成单元两方面的因素,重点设计了故障树的诊断流程,改进了以往故障诊断中出现的重复诊断的缺陷,优化了诊断过程。以飞机液压子系统为平台,与其他方法进行比较,得出该方法可以保证结果的正确性,并能节省诊断时间。     

多诊断资源参与下的诊断任务执行路径规划

远程协同故障诊断的一个关键环节是诊断任务分配,而多个分解后诊断任务执行顺序确定也是诊断任务分配环节中不可避免的一个内容;基于D算法,建立了关键路径规划方法来进行诊断任务执行路径规划,包括最长和最短关键路径规划算法;从诊断任务模型自身出发,研究了基于结构矩阵方法的路径规划方法;并以混凝土运输车制动系统故障诊断任务执行路径规划为例,进行了方法应用,验证了其有效性。     

工程机械远程故障监诊系统

工程机械由于其结构复杂,使用范围广,使得故障诊断与维护工作难度加大。针对这种情况设计一种工程机械的远程监控诊断系统,为分布在不同地理位置上的机械设备提供及时、有效、全面的诊断维护服务,缩短设备维修时间,提高设备利用率。系统基于ARM体系结构的嵌入式系统作为车载终端,通过GPRS网络与远程服务器交互。采用多传感器信息融合技术和故障树分析相结合增加了故障预测的准确率。     

基于有色Petri网的机械系统故障诊断研究

故障诊断对于机械系统的使用与维护起着重要的作用;为了提高机械系统故障诊断的效率以及直观性,提出了一种使用基于知识的故障诊断方法,即使用有色Petri网诊断方法建立一种通用机械系统故障诊断模型并进行分析;针对数控机床液压元件故障这一案例,首先获取其故障来源建立故障树;其次在故障树基础上运用有色Petri网建模工具CPNTools建立有色Petri网模型;最后对模型进行了仿真分析以模拟故障的传递,进行状态空间分析以判断模型安全性,结果表明所提出的建模方法能够使得故障传递更加直观化,快速了解故障的发展趋势,并表明此模型有着较强的易用性以及通用性。     

基于数据挖掘技术的飞机故障诊断专家系统设计

为适应现代民用飞机故障诊断的需求,应用飞机故障诊断历史经验,构建了飞机故障诊断维修知识库,在此基础上,研究了依据飞机维护历史经验知识和数据挖掘技术的故障诊断方法;应用关联分析方法实现了维修历史库的挖掘诊断,通过案例库的聚类分析,显著提高了案例库的检索效率;针对某型民机地面故障诊断的任务要求,设计了基于数据挖掘的机载设备故障诊断专家系统;通过输入真实故障信息,运行专家系统进行诊断分析,验证了所实现的基于数据挖掘的故障诊断专家系统具有较高的准确性。     

含约束的基于模型的诊断系统

在诊断空间中如何选取理想诊断是诊断系统面临的一个重要问题。在实际的诊断过程中,人们会利用限制条件排除不太可能的诊断,或者利用强制条件选取较优的诊断。按照这个思想,作者提出含约束的基于模型的诊断系统,通过增加依赖于应用领域的约束控制诊断空间,这是一种能够融入计算过程的选择诊断的机制,同时作者在系统拓扑结构的基础上给出了选取理想约束的理论依据。     

An ACO-RFD hybrid method to solve NP-complete problems

In this paper we hybridize ant colony optimization (ACO) and river formation dynamics (RFD), two related swarm intelligence methods. In ACO, ants form paths (problem solutions) by following each other’s pheromone trails and reinforcing trails at best paths until eventually a single path is followed. On the other hand, RFD is based on copying how drops form rivers by eroding the ground and depositing sediments. In a rough sense, RFD can be seen as a gradient-oriented version of ACO. Several previous experiments have shown that the gradient orientation of RFD makes this method solve problems in a different way as ACO. In particular, RFD typically performs deeper searches, which in turn makes it find worse solutions than ACO in the first execution steps in general, though RFD solutions surpass ACO solutions after some more time passes. In this paper we try to get the best features of both worlds by hybridizing RFD and ACO. We use a kind of ant-drop hybrid and consider both pheromone trails and altitudes in the environment. We apply the hybrid method, as well as ACO and RFD, to solve two NP-hard problems where ACO and RFD fit in a different manner: the traveling salesman problem (TSP) and the problem of the minimum distances tree in a variable-cost graph (MDV). We compare the results of each method and we analyze the advantages of using the hybrid approach in each case.     

A subspace learning-based feature fusion and open-set fault diagnosis approach for machinery components

Open-set fault diagnosis is an important but often neglected issue in machinery components, as in practical industrial applications, the failure data are in most cases unavailable or incomplete at the training stage, leading to the failure of most closed-set methods based on fault classifiers. Thus, based on the subspace learning methods, this paper proposes an open-set fault diagnosis approach with self-adaptive ability. First, for feature fusion, without using traditional dimensionality reduction methods, a data visualization method based on t-distributed stochastic neighbor embedding is employed for its ability in mining and enhancing the fault feature separability, which is the key in fault recognition. Then, for open-set fault diagnosis, to detect unknown fault classes and recognize known health states in only one model, the kernel null Foley-Sammon transform is applied to build a null space. To reduce the misjudgment rate and increase the detection accuracy, a self-adaptive threshold is automatically set according to the testing data. Moreover, the final recognition results are described as distances, which helps the operators to make maintenance decision. Case studies based on vibration datasets of a plunger pump, a centrifugal pump and a gearbox demonstrate the effectiveness of the proposed approach.     

动态系统实际故障可诊断性的量化评价研究

提出了一种新颖的动态系统实际故障可诊断性量化评价方法. 该方法无需设计任何诊断算法, 仅通过解析模型即可给出动态系统故障检测和隔离的难易程度, 从而为实现在系统设计阶段提高故障诊断能力的工程目标提供理论指导和参考依据. 首先, 通过标准化模型和等价空间变换, 将状态空间描述的随机动态系统实际故障可诊断性评价问题转化为概率统计中多元分布相似度判别的数学问题; 然后, 根据严格的数学证明, 指出距离相似度判别准则在进行可诊断性量化评价中存在的不足. 进而, 为弥补该不足, 利用故障矢量的分布概率以及不同故障矢量之间的余弦相似度, 设计基于方向相似度的可诊断性量化评价新方法; 最后, 通过数学仿真验证该方法的有效性和优越性.     

Reinforcement learning-based distant supervision relation extraction for fault diagnosis knowledge graph construction under industry 4.0

Fault diagnosis is the key concern in the operation and maintenance of industrial assets. A fault diagnosis knowledge graph (KG) can provide decision support to the engineers to efficiently conduct maintenance tasks. However, as a type of domain KG, it would be time-consuming to manually label the corpus collected from the multi-source including the maintenance log, handbook and article. Meanwhile, the existence of the noisy sentence in the multi-source corpus jeopardises the performance of relation extraction modelling. In order to address this issue, this paper proposes a distant supervision relation extraction (DSRE)-based approach to construct a fault diagnosis KG. In this approach, the ontology of the fault diagnosis KG is firstly designed. Subsequently, a DSRE algorithm named relation-aware-based sentence-level attention enhanced piecewise convolutional neural network with reinforcement learning strategy (PCNN-ATTRA-RL) is proposed. The algorithm can effectively lower the impact of noisy sentences and accurately label the relation of different entities when the labelled data is insufficient. In this algorithm, PCNN-ATTRA is designed as the DSRE classifier to effectively extract the relation between entity pairs. RL is conducted to remove the noisy sentence so as to further improve the performance. An experimental study based on the multi-source corpus collected from the real world reveals that the proposed approach shows merits in comparison with the state-of-the-art algorithms. Meanwhile, a fault diagnosis KG, which can greatly support the decision-making of the engineers in the fault diagnosis, is established via the proposed approach.     

Observer‐based fault diagnosis and self‐restore control for systems with measurement delays

The problems of fault diagnosis and fault‐tolerant control are considered for systems with measurement delays. In contrast to the present fault diagnosis and fault‐tolerant control approaches, which consider only the input delay and/or state delay, the main contribution of this paper consists of proposing a new observer‐based reduced‐order fault diagnoser construction approach and a design approach to dynamic self‐restore fault‐tolerant control law for systems with measurement delays. First, the time‐delay system is transformed into a delay‐free system in form by a special functional‐based delay‐free transformation approach for measurement delays. Then, the fault diagnosis is realized online via the proposed reduced‐order fault diagnoser. Using the results of fault diagnosis, two dynamic self‐restore control laws are designed to make the system isolated from faults. A numerical example demonstrates the feasibility and validity of the proposed scheme. © 2012 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

电传飞行控制系统MBIT故障诊断专家系统设计

针对电传飞控系统的特点和维护性要求,介绍了MBIT故障诊断专家系统的设计思路及实现方法。阐述了MBIT的功能与用途。构建了电传飞控系统MBIT故障诊断专家系统的体系结构,深入研究了如何建立故障知识库、制定推理机制、组建综合数据库和决策解释,并结合某型号,给出了具体的示例。工程实际使用过程中,利用本系统可以全面地对电传飞控系统进行有效的维护。     

实时故障诊断专家系统在PTA装置中的应用

精对苯二甲酸（pure terephthalic acid,PTA）是生产聚酯的重要原料。针对大型PTA装置故障的特点,提出将小波分析、模糊ART神经网络和专家系统等技术结合起来,开发了实时故障诊断专家系统。文中阐述了专家系统的具体实现,包括数据预处理模块、知识库组成及表达方式、人机界面、推理机的组成和诊断过程等。在某大型PTA装置中的成功应用表明：该系统具有预报准确、界面友好、易于维护等特点,有很好的通用性和推广价值。