in many manufacturing processes, the quality of a product is characterized by a non-linear relationship between a dependent variable and one or more independent variables. using nonlinear regression for monitoring nonlinear profiles have been proposed in the literature of profile monitoring which is faced with two problems 1) the distribution of regression coefficients in small samples is unkno...

In this paper, two Shewhart-type nonparametric control charts based on runs rules are developed for monitoring the changes in the process variability. The charts are based on two nonparametric tests for equality of variances. The performance of the proposed control charts is evaluated for the normal, light tailed and heavy tailed distributions through average run length using simulations.

In an attempt to improve the procedures for statistical process control many researchers have developed and proposed a variety of adaptive control charts in the last decade. The common characteristic of those charts is that one or more of the chart parameters (sampling interval, sample size, control limits) is allowed to change during operation taking into account current sample information. Du...

although control charts are very common to monitoring process changes, they usually do not indicate the real time of the changes. identifying the real time of the process changes is known as change-point estimation problem. there are a number of change point models in the literature however most of the existing approaches are dedicated to normal processes. in this paper we propose a novel appro...

Conventional statistical process control (SPC) charts require the normality assumption on the process response distribution. In reality, this assumption is often invalid. In such cases, it has been well demonstrated in the literature that results from control charts using the normality assumption may not be reliable in the sense that their actual false alarm rates could be substantially larger ...

The presence of dispersion/variability in any process is understood and its careful monitoring may furnish the performance of any process. The interquartile range (IQR) is one of the dispersion measures based on lower and upper quartiles. For efficient monitoring of process dispersion, we have proposed auxiliary information based Shewhart-type IQR control charts (namely IQRr and IQRp charts) ba...

O, ye who believe! If ye will aid, (the cause of) God, He will aid you, and plant your feet firmly. Verily, with every difficulty there is relief. Therefore, when thou art free (from thine immediate task), still labour hard. And to thy Lord turn (all) thy attention.

Unlike a Shewhart chart, the exponentially weighted moving average (EWMA) and cumulative sum (CUSUM) charts are memory control charts (also known as time weighted control charts) that are used for a quick detection of small shifts in the process mean. Control charts that combine information from present and past samples, like the EWMA and CUSUM charts have the ability to detect process changes ...

Shewhart control charts have previously been suggested as a process control tool for use in routine linear accelerator (linac) output verifications. However, a comprehensive approach to process control has not been investigated for linac output verifications. The purpose of this work is to investigate a comprehensive process control approach to linac output constancy quality assurance (QA). The...

The basic purpose of the economic design of the control charts is to find the optimum control charts parameters to minimize the process cost. In this paper, an R package, edcc (economic design of control charts), which provides a numerical method to find the optimum chart parameters is presented using the unified approach of the economic design. Also, some examples are given to illustrate how t...