Results 271 to 280 of about 424,805 (289)

Operating characteristics of X-bar charts with asymmetric control limits

IIE Transactions, 2001
When the assumptions behind the Shewhart chart are not met, policies other than the traditional 3-sigma limits may enable speedier and more economical detection of process change. If a process has unequal probabilities of downward and upward shifts, downward shifts of differing magnitude from upward shifts, and/or standard deviations after downward ...
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A study on the run sum X-bar control chart with unknown parameters

AIP Conference Proceedings, 2012
It is well known that the run sum control chart is a simple and powerful statistical process control tool in the monitoring of the process mean. The implementation of the run sum chart is generally based on the assumption that the process parameters are known.
Wei Lin Teoh, Michael B. C. Khoo
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Cross-correlation and X-bar -trend control charts for processes with linear shift

International Journal of Production Research, 2002
We developed a cross-correlation control chart to detect linear trends in a process. The observations from the process were collected at fixed intervals in a sampling period and were available as a batch at the end of the sampling period. The cross-correlation chart utilized two series: the average of the observations in a sampling period and the slope
M. Gültekin, J. R. English, E. A. Elsayed   +2 more
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Joint economic design of X-bar and R charts using simulated annealing

International Journal of Process Management and Benchmarking, 2014
The basic purpose of the economic design of a control chart is to find the optimum values for control chart parameters to minimise the total cost of process control. This paper deals with the joint economic design of X-bar and R charts. In the present work, simulated annealing which is one of the global optimisation techniques has been employed for the
Abhijeet Ganguly, Saroj Kumar Patel
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Economic design of x-bar control chart under hybrid maintenance policy

Journal of Quality in Maintenance Engineering, 2018
Purpose According to the relevance of product quality and machine degradation state, a hybrid maintenance policy is designed. The paper aims to discuss this issue. Design/methodology/approach Product quality control and machine maintenance are considered simultaneously in this policy.
Xiaomei Yang, Jianchao Zeng
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An effective joint X-bar and R chart to monitor the process mean and variance

International Journal of Productivity and Quality Management, 2007
When the shift occurs in both sample mean and standard deviation of a process, a joint X-bar and R charts can be used to monitor the process mean and variance. This paper deals with very simple and effective design of proposed X-bar and R charts to monitor the process mean and standard deviation.
D.R. Prajapati, P.B. Mahapatra
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X-bar control chart design with asymmetric control limits and triple sampling

The International Journal of Advanced Manufacturing Technology, 2018
The aim of the present study is to propose a control chart with asymmetric limits and triple sampling. Two topics have deserved closer attention of researchers in the process control field. The parameter variation is a construction approach for the most economic and robust control chart in the statistical control process.
Pedro Carlos Oprime, Naijela Janaina da Costa, Carlos Ivan Mozambani, Celso Luiz Gonçalves   +3 more
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Single-Subgroup Performance Measures and Diagnostic Procedures for X-Bar Control Charts

Journal of Engineering for Industry, 1994
Although Shewhart control charts have had a tremendous impact on quality improvement, the inability to precisely measure chart performance has limited their role, and subsequently overall effectiveness in the control of manufacturing processes. Measures of performance in terms of operational characteristics (OC) are defined on two distinct levels: (a ...
G. E. Rahn, S. G. Kapoor, R. E. DeVor
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Economic statistical design for x-bar control chart

At the present, the economic mathematical models are not widely used to find the optimal sample size and sampling frequency related to the implementation of the control chart because the models are quite complex, and difficult to evaluate and optimize. The objective of this thesis is to develop an understandable economic mathematic model that is easily
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Frequency Distribution Supporting Recognition of Unnatural Patterns on Shewhart X-bar Chart

2001
This paper describes a method supporting recognition of unnatural patterns on a Shewhart X chart by analysis of its frequency distribution. It has been implemented as a program that simulates data from a statistically controlled process as well as from a process affected by patterns.
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