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Showing 1 to 20 of 71 for “"Control chart"”.
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A robust Shewhart control chart adjustment strategy
The standard Shewhart control chart for monitoring process stability is generalized by selecting a point in time at which the distance between the control limits is reduced. Three cost models are developed to describe the total cost per unit time of monitoring the mean of a process using both the …
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Control chart procedures based on cumulative gauging scores
Control charts based on cumulative gauging scores rely on gauge scoring systems used for transforming actual observations into integer gauging scores. In some cases, the gauging scores are easy to obtain by using a mechanical device such as in the go-no-go inspection process. Thus, accurate …
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The Minimax control chart for multivariate quality control
A new multicharacteristic control chart designed to detect shifts in the mean of a multivariate process is proposed. It is assumed that the correlation matrix is known and that the distribution of the data is multivariate normal. The new chart is based on the minimum standardized sample mean …
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A Performance Analysis of the Minimax Multivariate Quality Control Chart
A performance analysis of three different Minimax control charts is performed with respect to their Chi-Square control chart counterparts under several different conditions. A unique control chart must be constructed for each process described by a unique combination of quality characteristic mean …
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Intergration of control chart and pattern recognizer for bivariate quality control
… of the existing multivariate statistical process control schemes are only effective in rapid detection but suffer high false alarm. This is referred to as imbalanced performance monitoring. The problem becomes more complicated when dealing with small mean shift particularly in identifying the …
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A comparison of alternative methods to the shewhart-type control chart
A control chart that simultaneously tracks the mean and variance of a normally distributed variable with no compensation effect is defined in this work. This joint control chart is compared to five other charts: an Χ chart, an s² chart, a Reynolds and Ghosh chart, a Repko process capability plot, …
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Fault detection in a continuous production line using adaptive control chart limits
… a manufacturing line to determine which process control charts and equations are best-suited for real-time monitoring of the line. By evaluating the performance of X-Bar Charts, regressions, and S Charts in monitoring the various processes on the Industrial Steel manufacturing line, a different …
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The application of a single control chart for dependent variables in multivariate quality control
Most control charts monitor only one quality characteristic. There are, however, many manufactured products for which good quality requires meeting specifications in more than one physical characteristic. Typical practice when dealing with multiple quality characteristics is to take a separate …
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Monitoring Markov Dependent Binary Observations with a Log-Likelihood Ratio Based CUSUM Control Chart
… probability matrix is . We construct a CUSUM control chart for monitoring a proportion with correlated binary observations. First, we use the probability structure of a first-order Markov chain to derive a log-likelihood ratio based CUSUM control statistic. Then, we model this CUSUM statistic …
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Statistical process control by quantile approach.
Most quality control and quality improvement procedures involve making assumptions about the distributional form of data it uses; usually that the data is normally distributed. It is common place to find processes that generate data which is non-normally distributed, e.g. Weibull, logistic or …
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Some Contributions to Tolerance Intervals and Statistical Process Control
… play an important role in statistical process control along with control charts. When constructing a tolerance interval or a control chart for the mean of a quality characteristic, the normality assumption can be justifiable at least in an approximate sense. However, in applications where the …
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Surveillance of Poisson and Multinomial Processes
… natural choice for on-going surveillance is the control chart; however, the chart must be constructed in a way that accommodates the situation at hand. Two scenarios involving attribute control charting are investigated here. The first scenario involves Poisson count data where the area of …
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Variable Sampling Rate Control Charts for Monitoring Process Variance
… items will not meet specifications. Statistical control charts for monitoring process variance can be used to detect an increase in the variability of the output of a process so that the situation can be repaired and product uniformity restored. Control charts that increase the sampling rate when …
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Process control: a dynamic programming approach
In this thesis, a cost based process control model is formulated. A dynamic programming approach is used and along with the techniques of Bayesian decision theory, an optimal set of steady state control policies are shown to exist which are dependent upon prior beliefs about the condition of the …
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Cumulative sum quality control charts design and applications
Classical Statistical Process Control Charts are essential in Statistical Control exercises and thus constantly obtained attention for quality improvements. However, the establishment of control charts requires large-sample data (say, no less than I 000 data points). On the other hand, we notice …
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Nonparametric procedures for process control
Three nonparametric control chart procedures are developed. The procedures are designed to detect any shift in the median of a sequence of observations from a specified control value. The first two procedures require that groups of g ≥ 1 observations be made sequentially on the output of the …
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X control charts in the presence of correlation
In traditional quality control charts, fixed sampling interval (FSI) schemes are used where the time between samples has fixed intervals. More efficient methods called variable sampling interval (VSI) schemes have been developed where one takes the next observation sooner than usual if there is an …
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Nonparametric procedures for process control when the control value is not specified
In industrial production processes, control charts have been developed to detect changes in the parameters specifying the quality of the production so that some rectifying action can be taken to restore the parameters to satisfactory values. Examples of the control charts are the Shewhart chart and …
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