Nonlinear Chemical Process Fault Diagnosis Using Ensemble Deep Support Vector Data Description.

Anomaly detection using improved deep SVDD model with data structure preservation

Monitoring of solid-state fermentation of wheat straw in a pilot scale using FT-NIR spectroscopy and support vector data description

Complex industrial processes are often non-linear and non-Gaussian, while the traditional principal component analysis (PCA) method assumes that the data are Gaussian and linear. In this paper, a novel process monitoring method based on maximum information coefficient-PCA (MIC-PCA) and support vector data description (SVDD) is proposed. First, the covariance matrix is replaced by the MIC matrix which can measure the non-linear correlation between the variables. Then the SVDD models are built in the principal component subspace (PCS) and the residual subspace (RS) to improve the monitoring of non-linear and non-Gaussian processes. Finally, the feasibility and effectiveness of the proposed method are validated by high-pressure and low-density polyethylene (LDPE) industrial process.

Acoustical damage detection of wind turbine blade using the improved incremental support vector data description

Black rice is an important rice species in Southeast Asia. It is a common phenomenon to pass low-priced black rice off as high-priced ones for economic benefit, especially in some remote towns. There is increasing need for the development of fast, easy-to-use, and low-cost analytical methods for authenticity detection. The feasibility to utilize near-infrared (NIR) spectroscopy and support vector data description (SVDD) for such a goal is explored. Principal component analysis (PCA) is used for exploratory analysis and feature extraction. Another two data description methods, i.e., k-nearest neighbor data description (KNNDD) and GAUSS method, are used as the reference. A total of 142 samples from three brands were collected for spectral analysis. Each time, the samples of a brand serve as the target class whereas other samples serve as the outlier class. Based on both the first two principal components (PCs) and original variables, three types of data descriptions were constructed. On average, the optimized SVDD model achieves acceptable performance, i.e., a specificity of 100% and a sensitivity of 94.2% on the independent test set with tight boundary. It indicates that SVDD combined with NIR is feasible and effective for authenticity detection of black rice.

Support vector data description (SVDD) is an effective algorithm for nonlinear process monitoring. However, the conventional SVDD method can't deal with the incipient faults well, which has the small fault amplitude and is easy to be overlapped by industrial noises. Aiming at this problem, an improved SVDD, called probability related SVDD in local variable field (LVPSVDD), is proposed to detect the incipient faults in nonlinear processes. Firstly, the method divides process variables into several local variable fields by hierarchical clustering, and the SVDD model of each variable field is built. Then the sliding window technology is applied to the SVDD distance statistics, and the probability distribution change in the sliding window is measured by Kullback Leibler divergence (KLD). For each local variable field, the corresponding probability related monitoring statistic is developed to replace the original distance statistic. Finally, the global monitoring statistic is obtained by integrating the monitoring results of all local variable fields with Bayesian inference strategy. The method is illustrated with simulation on the continuous stirred tank reactor (CSTR).

Enhanced multiclass support vector data description model for fault diagnosis of gears

Converting SVDD scores into probability estimates: Application to outlier detection

Bearing performance degradation assessment is of great significance for proactive maintenance and near-zero downtime. For this purpose, a novel assessment method is proposed based on lifting wavelet packet symbolic entropy (LWPSE) and support vector data description (SVDD). LWPSE is presented for feature extraction by jointing use of lifting wavelet packet transform and symbolic entropy. Firstly, the LWPSEs of bearing signals from normal bearing condition are extracted to train an SVDD model by fitting a tight hypersphere around normal samples. Then, the relative distance from the LWPSEs of testing signals to the hypersphere boundary is calculated as a quantitative index for bearing performance degradation assessment. The feasibility and efficiency of the proposed method were validated by the life-cycle data obtained from NASA’s prognostics data repository and the comparison with Hidden Markov Model (HMM). Finally, the assessment results were verified by the envelope spectrum analysis method based on empirical mode decomposition and Hilbert envelope demodulation.

Data imbalance causes learning bias in class identification techniques. A major cause for limited success in the prediction of liquefaction potential by various pattern recognition techniques is because of a liquefaction to nonliquefaction data class imbalance. It is suggested to use a support vector data description (SVDD) strategy to compensate the minority data. SVDD is used to generate virtual data points for the minority class bearing the same characteristics as the nonvirtual samples. Then an adaptive neuro-fuzzy inference system (ANFIS) classifier is employed to determine the liquefaction threshold. The ANFIS predictions are then examined by evaluating the coefficient of determination (COD) and comparing it with the Bayesian updating method. It is shown that for the liquefied data the approach is as efficient as the Bayesian method, but great improvement in the recognition rates of the nonliquefied data have been achieved.

A compound fault diagnosis model for photovoltaic array based on 1D VoVNet-SVDD by considering unknown faults

Fault detection in dynamic plant-wide process by multi-block slow feature analysis and support vector data description

With the development of deep convolutional neural networks in recent years, the network structure has become more and more complicated and varied, and there are very good results in pattern recognition, image classification, scene classification, and target tracking. This end-to-end learning model relies on the initial large dataset. However, many data are gradually obtained in practical situations, which contradict the deep learning of one-time batch learning. There is an urgent need for an incremental learning approach that can continuously learn new knowledge from new data while retaining what has already been learned. This paper proposes an incremental learning algorithm based on convolutional neural network and support vector data description. CNN and AM-Softmax loss function are used to represent and continuously learn image features. Support vector data description is used to construct multiple hyperspheres for new and old classes of images. Class-incremental learning is achieved by the increment of hyperspheres. The experimental results show that the incremental learning method proposed in this paper can effectively extract the latent features of the image and adapt it to the learning situation of the class-increment. The recognition accuracy is close to batch learning.

Support Vector Data Description (SVDD) methods have been successfully applied to hyperspectral anomaly detection. Unfortunately, the performance of SVDD methods suffers when noisy or non-informative bands are present in the data. If a set of sparse features could be identified for these techniques, the resulting data may improve SVDD performance while enjoying the benefits of decreased processing overhead. Although band selection has been investigated in previous efforts, this work builds on recent research that has resulted in the development of a theoretical framework for signal classification with sparse representation using L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> measures.

Feature extraction methods in the industrial process may affect the performance of process monitoring and fault assessment. In order to reduce the influence of model preference, a novel fault assessment method integrating global and local structure information is proposed by using the strategy of parallel extraction and weighted combination. First, kernel sparse locally linear embedding and kernel principal component analysis models are constructed to handle nonlinear system states and describe the local and global information in parallel. Second, the fault assessment indicators are obtained through support vector data description models. Then, a comprehensive fault assessment index is established by the weighted fusion method, which can keep the global and local neighbor information of the original sample space, and thus more feature information is included. Finally, the feasibility and effectiveness of the proposed assessment method are illustrated by the application in the simulation process of Tennessee Eastman Process, and the results show that the fusion of two basic models can bring a model with better generalization performance than a single model.