A combined method of diagnostics is proposed for a class of nonlinear multivariate processes where fast and slow faults are observed with essentially different rates of their development. Because fast faults occur against the background of the slow ones and have many common symptoms, the process turns out nonstationary. That is why it is proposed to use kernel principal component analysis with a moving window for monitoring purposes. The faults are identified with Fisher discriminant analysis started up when the fault is detected, and through some moments it is blocked to reduce blurring of classes. The efficiency of the method is demonstrated by the example of diagnostics of hydrocarbon pyrolysis process.
The application of chemometrics methods to continuous monitoring and diagnostics of sintering process faults for improving iron‐ore sinter quality is considered in the article. The sintering process is among complex multivariate processes.
A number of agglomeration process faults have often similar symptoms, resulting in late fault detection by an operator and as a consequence, wrong process control decisions. To support the efficient operative decision making, it is proposed to use the process fault monitoring and diagnostics system.
The proposed system uses a two‐level neural network (NN) diagnostic model. The high‐level neural network is used to localize the process faults whereas their reasons are determined by the low‐level neural networks. To reduce essentially the time of HL‐NN training and retraining, the task dimension is preliminarily reduced with the principal component analysis method so that the scores obtained from initial data are fed into high‐level neural network inputs. The use of principal component analysis allowed detection of sintering process faults with T2 and Q statistics. Only upon detecting the fault, a NN diagnostic model starts working to determine the fault reason. The system algorithm provides for special measures to prevent the NN from possible “loss” of the identified fault due to operator's inactivity.
To increase the diagnosis depth for controlling fault symptoms that are evident on the sinter cake surface, optical digital cameras are installed and images from them are processed with proposed algorithms on the basis of fuzzy clusterization to take into account uncertainties in the initial information.
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