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11.
Chi-man Vong Pak-kin Wong Weng-fai Ip 《Engineering Applications of Artificial Intelligence》2011,24(7):1281-1294
Whenever there is any fault in an automotive engine ignition system or changes of an engine condition, an automotive mechanic can conventionally perform an analysis on the ignition pattern of the engine to examine symptoms, based on specific domain knowledge (domain features of an ignition pattern). In this paper, case-based reasoning (CBR) approach is presented to help solve human diagnosis problem using not only the domain features but also the extracted features of signals captured using a computer-linked automotive scope meter. CBR expert system has the advantage that it provides user with multiple possible diagnoses, instead of a single most probable diagnosis provided by traditional network-based classifiers such as multi-layer perceptions (MLP) and support vector machines (SVM). In addition, CBR overcomes the problem of incremental and decremental knowledge update as required by both MLP and SVM. Although CBR is effective, its application for high dimensional domains is inefficient because every instance in a case library must be compared during reasoning. To overcome this inefficiency, a combination of preprocessing methods, such as wavelet packet transforms (WPT), kernel principal component analysis (KPCA) and kernel K-means (KKM) is proposed. Considering the ignition signals captured by a scope meter are very similar, WPT is used for feature extraction so that the ignition signals can be compared with the extracted features. However, there exist many redundant points in the extracted features, which may degrade the diagnosis performance. Therefore, KPCA is employed to perform a dimension reduction. In addition, the number of cases in a case library can be controlled through clustering; KKM is adopted for this purpose. In this paper, several diagnosis methods are also used for comparison including MLP, SVM and CBR. Experimental results showed that CBR using WPT and KKM generated the highest accuracy and fitted better the requirements of the expert system. 相似文献
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《Measurement》2016
Because planetary gear is characterized by its small size, light weight and large transmission ratio, it is widely used in large-scale, low-speed and heavy-duty mechanical systems. Therefore, the fault diagnosis of planetary gear is a key to ensure the safe and reliable operation of such mechanical equipment. A fault diagnosis method of planetary gear based on the entropy feature fusion of ensemble empirical mode decomposition (EEMD) is proposed. The intrinsic mode functions (IMFs) with small modal aliasing are obtained by EEMD, and the original feature set is composed of various entropy features of each IMF. To address the insensitive features in the original feature set and the excessive feature dimension, kernel principal component analysis (KPCA) is used to process the original feature set. Kernel principal component extraction and feature dimension reduction are performed. The fault diagnosis of planetary gear is eventually realized by applying the extracted kernel principal components and learning vector quantization (LVQ) neural network. The experiments under different operation conditions are carried out, and the experimental results indicate that the proposed method is capable of extracting the sensitive features and recognizing the fault statuses. The overall recognition rate reaches to 96% when the motor output frequency is 45 Hz and the load is 13.5 N m, and the fault recognition rates of the normal gear, the gear with one missing tooth and the broken gear can reach to 100%. The recognition rates of different fault gears under other operation conditions also can achieve better results. Thus, the proposed method is effective for the diagnosis of planetary gear faults. 相似文献
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In this paper, a two-step phase partitioning strategy is proposed. Firstly, the number of phases is automatically determined according to the intra-class and inter-class similarity of feature space data, thus avoiding excessive manual intervention. Secondly, the phases are partitioned by step-wise adding the kernel entropy extended load matrix (KEELM), avoiding the wrong division of phases caused by unstable state of working condition conversion. A process monitoring model based on multiway kernel entropy independent component analysis (MKEICA) is constructed in each sub-phase to deal with complex batch processes with nonlinear and non-Gaussian properties. A new statistics index based on the idea of high order cumulant analysis (HCA) is constructed in each sub-phase for process monitoring. Compared with the traditional second-order statistics, it can obtain high-order statistical information. Finally, the proposed method is applied to the penicillin simulation platform process and compared with the traditional multiway kernel independent components analysis (MKICA) and HCA methods to verify the effectiveness of the method that is mentioned above. 相似文献
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基于KPCA的SBR过程监视 总被引:4,自引:0,他引:4
序批式反应器生化污水处理系统(SBR)具有复杂的生化反应机理,其固有的严重非线性、持续时间有限、非稳态运行等给其过程监视带来特殊困难。核主元分析(KPCA)方法通过集成算子与非线性核函数计算高维特性空间的主元成分,有效捕捉过程变量中的非线性关系。将KPCA技巧应用到序批式反应器生化污水处理系统,建立了基于KPCA的SBR污水处理过程在线监视策略。在监视暴风雨事件等典型的SBR过程异常状态时,统计指标变化灵敏,诊断及时。与线性PCA相比,显示出更高的过程监视性能。 相似文献
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分析了文本分类系统的一般模型及现有技术,在应用了核主成分分析的特征降维方法进行处理后,提出了一种基于样本中心的径向基( RBF)神经网络文本分类算法,并且引入了聚类算法的核心思想,来改进误差反向传播(BP)神经网络分类算法收敛速度较慢的缺点.实验结果表明, RBF网络与BP网络相比,具有较高的运算速度和较强的非线性映射能力,在收敛速度和准确程度上也有更好的分类效果. 相似文献
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遗传算法和粒子群算法等智能搜索技术可在较少的时间开销内给出问题的近似解.量子粒子群优化(QPSO)算法是在经典的微粒群算法的基础上所提出的一种高效的收敛性,稳定性的进化算法.将操作简单而收敛快速的QPSO算法运用于训练支持向量机(SVM),结合KPCA特征提取方法,用于人脸图像的分类识别中,为人脸识别问题的研究开辟了新的途径. 相似文献
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提出了一种新的判别 核窗宽方法,进而研究了基于判别核窗宽的KPCA和LPP在掌纹识别中的应用。首先根据训练 样本和类标签计 算类内核窗宽和类间核窗宽;在分类密集区选择较小窗宽,在分类稀疏区选择较大窗宽,可 以有效提取数 据的关联特征;然后运用基于判别核窗宽的KPCA和LPP方法提取低维特征向量,计算特征向 量间的余弦 距离进行掌纹匹配;最后运用PolyU掌纹图像库,对本文算法进行测试。实验结果表明,与 传统算法相比, 本文算法的识别率最高,识别时间小于0.6s,验证了方法的有效性 。 相似文献