quality control plays an important role in increasing the product quality. fuzzy control charts are more sensitive than shewhart control chart. hence, the correct use of fuzzy control chart leads to producing better-quality products. this area is complex because it involves a large scope of industries, and information is not well organized. in this research, we provide a literature review of th...

A major impediment to practitioner acceptance of the economic design approach to control charts is the complicated nature of the underlying optimization problem even under standard process assumptions. The economic approach to determining the optimal control limits requires estimating the derivatives of performance curves that are typically obtained via simulation. For this gradient estimation ...

in this paper, first the available single charting methods, which have been proposed to detect simultaneous shifts in a single process mean and variance, are reviewed. then, by designing proper simulation studies these methods are evaluated in terms of in-control and out-ofcontrol average run length criteria (arl). the results of these simulation experiments show that the ewma and ewms methods ...

in this research, a new control policy for the acceptance sampling problem is introduced. decision is made based on the number of defectives items in an inspected batch. the objective of the model is to find a constant control level that minimizes the total costs, including the cost of rejecting the batch, the cost of inspection and the cost of defective items. the optimization is performed by ...

in this research, an iterative approach is employed to recognize and classify control chart patterns. to do this, by taking new observations on the quality characteristic under consideration, the maximum likelihood estimator of pattern parameters is first obtained and then the probability of each pattern is determined. then using bayes’ rule, probabilities are updated recursively. finally, when...

control chart is the most well-known chart to monitor the number of nonconformities per inspection unit where each sample consists of constant size. generally, the design of a control chart requires determination of sample size, sampling interval, and control limits width. optimally selecting these parameters depends on several process parameters, which have been considered from statistical and...

introduction: acceptance test is a necessary procedure after spect system installation. the goal of this test is to reveal system's present condition, to compare it with manufacturer's specifications and also as a base for later tests. methods: this study investigated four spect systems in tehran. all of the quality control tests are performed on the basis of nema and iaea recommendations and b...