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635 results about "Control limits" patented technology

Control limits, also known as natural process limits, are horizontal lines drawn on a statistical process control chart, usually at a distance of ±3 standard deviations of the plotted statistic from the statistic's mean.

Method and apparatus for adaptively controlling a state of charge of a battery array of a series type hybrid electric vehicle

A series type hybrid electric vehicle including a generator set having an internal combustion engine and a generator, a battery array and at least one electric motor includes a controller for maintaining a state of charge of the battery array within a control limit. A controller of the vehicle determines if the vehicle is in one of a plurality of forward driving modes, compares a state of charge of the battery array to an upper control limit associated with a forward driving mode, decreases generated by the generator, if the state of charge is equal to or greater than the associated upper control limit, and increases the power generated by the generator, if the state of charge is less than the associated upper control limit. A method of controlling the state of charge of the battery array includes determining if the vehicle is in one of a plurality of forward driving modes, comparing a state of charge of the battery array to an upper control limit associated with a forward driving mode, decreasing the power generatred by the generator, if the state of charge is equal to or greater than the associated upper control limit, and increasing the power generated by the generator, if the state of charge is less than the associated upper control limit.
Owner:TRANSPORTATION TECH

PCA (Principle Component Analysis) model based furnace temperature and tension monitoring and fault tracing method of continuous annealing unit

The invention relates to a fault monitor and diagnosis method of a continuous annealing unit, in particular to a PCA (Principle Component Analysis) model based furnace temperature and tension monitoring of a continuous annealing unit, mainly comprising the following steps of firstly, according to process variable data obtained in the field, and establishing a temperature and tension monitor modelby utilizing a principle component analysis PCA method; secondly, establishing an off-line model and calculating the T2 statistics quantity and the SPE statistics quantity as well as contributed control limits thereof by utilizing the data, obtained in step one, when process variable is in a normal work condition; thirdly, applying an on-line model, calculating the T2 statistics quantity and the SPE statistics quantity of current data, monitoring whether a current state is normal or not according to information supplied by the off-line model, and giving alarm signals if abnormal; fourthly, determining a leading variable which causes a fault by utilizing contribution of the T2 statistics quantity and contribution of the SPE statistics quantity. The invention monitors the furnace temperature and tension in real time in the production process and traces back a fault reason for leading to system abnormality when the abnormality occurs.
Owner:SHANGHAI BAOSTEEL IND TECHNOLOGICAL SERVICE +1

Strip steel quality forecasting, furnace condition early-warning and fault diagnosis method based on partial least square

The invention relates to a strip steel quality forecasting, furnace condition early-warning and fault diagnosis method, in particular to a strip steel quality forecasting, furnace condition early-warning and fault diagnosis method based on partial least square, comprising the following steps: model selection: multiple models are adopted to describe the process characteristics of corresponding steel types; data preprocessing: data alignment based on the model is carried out, synchronization relation of process input and quality output is built and data dimensionless treatment is carried out to eliminate effect of process data on modeling precision owning to non-unity of physical units; an off-line model building; a PLS (partial least square) model for strip steel quality and process variable is built by utilizing a great amount of historical data in normal working conditions; determining control limit of an monitor-control index; determining variable quantity control limit; and on-line forecasting and on-line detection and fault diagnosis. In the invention, the model for the strip steel quality and the process variable is built by PLS algorithm, so as to realize real-time quality forecasting, process monitoring and fault diagnosis.
Owner:SHANGHAI BAOSTEEL IND TECHNOLOGICAL SERVICE +1

Online updating method of principal component analysis monitoring model

The invention relates to an online updating method of a principal component analysis monitoring model. The method comprises the following steps that: 1) A model online updating system comprising data acquisition equipment and a monitoring computer is arranged in industry field; 2) A traditional principal component analysis (PCA) modeling module uses historical data to establish a PCA initial monitoring model; 3) After the monitoring begins, a mean value variance updating module calculates a mean value and a standard deviation sigma' of a new model according to real-time process data and the current PCA model; 4) A projection point calculation module calculates a residual vector of a new sample and transmits to a residual determination module; 5) The residual determination module determines an updating method of a projection direction according to a size of a residual vector die; if the residual is large, a principal component space adjusting module is called; if the residual value is small, a principal component direction fine adjusting module is called; finally a load vector P' nk and a characteristic value matrix lambda' kk of the new model is obtained; 6) A control limit updating module carries out control limit and updating on statistical magnitude of the model; the system finally outputs the new model omega' which is used for online monitoring and fault diagnosis during an industrial process.
Owner:TSINGHUA UNIV

ICA-PCA multi-working condition fault diagnosis method based on local neighborhood standardization and Bayesian inference

The invention discloses an ICA-PCA multi-working condition fault diagnosis method based on local neighborhood standardization and Bayesian inference. The method firstly carries out independent sampling of each normal working condition during an industrial course to obtain a training dataset, carries out the local neighborhood standardization of the training dataset to obtain a dataset which follows single distribution, and then uses an ICA-PCA method to respectively analyze and process Gaussian features and non-Gaussian features of the dataset so as to obtain an overall model. At an online monitoring stage, independent and repeated sampling is carried out to industrial course data, a plurality of statistical quantities are acquired by applying the model to carry out analysis and processing after the local neighborhood standardization processing, then the multiple statistical quantities are combined into one statistical quantity by the Bayesian inference, and a fault diagnosis result is acquired by comparing control limits. In comparison with traditional fault diagnosis methods, the ICA-PCA multi-working condition fault diagnosis method based on the local neighborhood standardization and the Bayesian inference disclosed by the invention can simplify processing courses, improve diagnosis effects and improve course monitoring performance, and can also make workers' monitoring and observation convenient, make for avoiding safety hidden dangers and guarantee normal running of the industrial course.
Owner:JIANGNAN UNIV

Method of monitoring faults in sections for intermittent control system

InactiveCN103279123AThe phase division complies withThe phase division is more in line with the batch process actually in line withElectric testing/monitoringFuzzy clustering analysisPrincipal component analysis
The invention discloses a method of monitoring faults in sections for an intermittent control system and relates to a fault monitoring method. Firstly, a plurality of batches of collected intermittent process data are standardized in a way of expanding variables, and a data matrix on each sampling time is subjected to principal component analysis; secondly, a fuzzy C-means clustering is a fuzzy clustering analysis method which is suitable for soft partition and is generated through combining a fuzzy set theory and a k-means clustering; and thirdly, after segmentation is finished, an improved MPCA (Multiway Principal Component Analysis) model with a time varying principal element covariance on the basis of expanding variables is established on each subphase, then when on-line monitoring is carried out, which phase a new batch of data belongs to is judged, whether the data exceeds the fault monitoring control limit or not is calculated and judged, if so, a fault occurs, and the fault monitoring in sections ends. According to the invention, process multi-phase partition is more accurate, misinformation and missing report rates in monitoring are reduced, and the practical application and operability are strong.
Owner:SHENYANG INSTITUTE OF CHEMICAL TECHNOLOGY

Method for monitoring process of fused magnesium furnace based on improved supervised kernel locally linear embedding method

The invention provides a method for monitoring the process of a fused magnesium furnace based on an improved supervised kernel locally linear embedding method, and relates to the technical field of fault monitoring and diagnosis. The method includes the steps of mapping sample data X to a high dimensional feature space [phi](X) by using a kernel function; selecting the number of k neighbor points through a MKSLLE (Modified supervised kernel locally linear embedding) algorithm, and adding a regular term when constructing a reconstruction weight matrix; performing dimensionality reduction for an objective function composed of a KPCA-combined global preserving features and local preserving features, and obtaining a mapping matrix from a high dimensional data space to a low dimensional feature space and a coefficient matrix through approximate calculation; and constructing a Hotelling T2 statistic and an SPE statistic and determining control limits thereof. According to the invention, abnormalities and faults can be monitored online in real time in the working process of a fused magnesium furnace, the accuracy of fault monitoring is effectively improved, the occurrence of false alarms and false negatives is reduced, the property loss is reduced, and the personal safety of working staff is guaranteed.
Owner:NORTHEASTERN UNIV

Non-linear procedure failure testing method based on two-dimensional dynamic kernel principal component analysis

Disclosed is a non-linear process fault detection method based on two-dimensional dynamic kernel principal component analysis, belonging to the fault detection technical field; the method comprises the following steps: the first step is to determine the sampling parameters, namely, to judge the execution process, determine the sampling parameters, select the data parameters which affect the fault, and then judge whether to carry through training or testing; the second step is training, that is, to collect the data of normal work, pick up the non-linear principal component of the training data through two-dimensional dynamic kernel principal component analysis, calculate the square prediction error of the training data and determine the control limit; the third step is testing, that is, to collect the online observation data, pick up the non-linear principal component of the online observation data through two-dimensional dynamic kernel principal component analysis, calculate the square prediction error of the real-time online observation data, compare the control limit of the square prediction error of the real-time online observation data with the control limit of the square prediction error of the training data, display and gives an alarm if the control limit of the former exceeds that of the latter. The invention can timely detect the fault in the production process and reduce losses in the industrial production process.
Owner:NORTHEASTERN UNIV
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