Efficient homogeneously weighted dispersion control charts with an application to distillation process. (12th May 2021)

• Record Type: Journal Article
• Authors: Abbasi, Saddam Akber; Nassar, Sara Hussam; Aldosari, Mashael Mohammed; Adeoti, Olatunde A.
• Is Part Of: Quality and reliability engineering international. Volume 37:Number 8(2021)
• Page Start: 3221
• Page End: 3241
• Publication Date: 2021-05-12
• Subjects: control chart -- process dispersion -- HWMA -- average run length -- extra quadratic loss; Reliability (Engineering) -- Periodicals; Quality control -- Periodicals; High technology -- Periodicals; 620.00452
• DOI: 10.1002/qre.2904
• Languages: English
• ISSNs: 0748-8017

Abstract

Abstract: Monitoring disturbances in process dispersion using control chart is mostly based on the assumption that the quality characteristic follows normal distribution, which is not the case in many real‐life situations. This paper proposes a set of new dispersion charts based on the homogeneously weighted moving average (HWMA) scheme, for efficient detection of shifts in process standard deviation (σ). These charts are based on a variety of σ estimators and are investigated for normal as well as heavy tailed symmetric and skewed distributions. The shift detection ability of the charts is evaluated using different run length characteristics, such as average run length (ARL), extra quadratic loss (EQL), and relative ARL measures. The performance of the proposed HWMA control charts is also compared with the existing EWMA dispersion charts, using different design parameters. Furthermore, an illustrative example is presented to monitor the vapor pressure in a distillation process.