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simultaneous-monitoring
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The Max EWMAMS control chart for joint monitoring of process mean and variance with individual observations
, Article Quality and Reliability Engineering International ; Volume 27, Issue 4 , SEP , 2011 , Pages 499-514 ; 07488017 (ISSN) ; Niaki, S. T. A ; Sharif University of Technology
2011
Abstract
A traditional approach to monitor both the location and the scale parameters of a quality characteristic is to use two separate control charts. These schemes have some difficulties in concurrent tracking and interpretation. To overcome these difficulties, some researchers have proposed schemes consisting of only one chart. However, none of these schemes is designed to work with individual observations. In this research, an exponentially weighted moving average (EWMA)-based control chart that plots only one statistic at a time is proposed to simultaneously monitor the mean and variability with individual observations. The performance of the proposed scheme is compared with one of the two...
Design of a Statistical Control Chart for Simultaneous Monitoring and Fault Isolation of Mean Vector and Covariance Matrix of Multivariate Multistage Processes
, M.Sc. Thesis Sharif University of Technology ; Akhavan Niaki, Taghi (Supervisor)
Abstract
In modern industries, multivariate multistage auto-correlated processes are widely used to ensure productivity and product quality. Interconnections between work stations bring a challenging task in detecting various shifts and identifying their root causes. In addition, simultaneous monitoring process mean and variability with single control chart methods has gained considerable attention throughout these years. In this article, a double-max multivariate exponentially weighted moving average (DM-MEWMA) chart is proposed based on two novel statistics to monitor the parameters of multivariate multistage auto-correlated processes jointly. Prior knowledge of variation propagation has been used...
A double-max MEWMA scheme for simultaneous monitoring and fault isolation of multivariate multistage auto-correlated processes based on novel reduced-dimension statistics
, Article Journal of Process Control ; Volume 29 , May , 2015 , Pages 11-22 ; 09591524 (ISSN) ; Akhavan Niaki, S. T ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
In this article, a double-max multivariate exponentially weighted moving average (DM-MEWMA) chart is proposed to jointly monitor the parameters of a multivariate multistage auto-correlated (MMAP) process. While the process is assumed to work in a linear state-space form, two modified statistics are combined into a novel statistic to monitor the mean vector and the covariance matrix of the MMAP simultaneously. Besides, prior knowledge of variation propagation is used so that the chart has both a fault identification power and capability of working with the sample size of one. A statistical test shows that the two proposed statistics are independent of the process dimension. Monte Carlo...
A New Control Scheme for Phase-II Monitoring of Simple Linear Profiles in Multistage Processes
, Article Quality and Reliability Engineering International ; Volume 32, Issue 7 , 2016 , Pages 2559-2571 ; 07488017 (ISSN) ; Akhavan niaki, S. T ; Sharif University of Technology
John Wiley and Sons Ltd
Abstract
In this paper, a new control scheme is proposed for Phase-II monitoring of simple linear profiles in multistage processes. In this scheme, an approach based on the U transformation is first applied to remove the effect of the cascade property involved in multistage processes. Then, a single max-EWMA-3 control statistic is derived based on the adjusted parameter estimates for simultaneous monitoring of all the parameters of a simple linear profile in each stage. Not only is the proposed scheme able to detect both increasing and decreasing shifts but it also has the feature of identifying the out-of-control parameter responsible for the source of process shift. Using extensive simulation...
Study of emi-based damage type identification in a cracked metallic specimen repaired by a composite patch
, Article Russian Journal of Nondestructive Testing ; Volume 56, Issue 6 , 2020 , Pages 540-548 ; Ghasemi, R ; Mohammadi, B ; Sharif University of Technology
Pleiades Publishing
2020
Abstract
Abstract: Using adhesively bonded composite patch repairs has been increased in various industries to improve the structural integrity of cracked metallic structures in recent decades. Monitoring of crack propagation and composite patch debonding, as two dominant failure mechanisms in this repair technique, plays a significant role in the integrity assessment of the component. This research conducts an experimental investigation on the simultaneous monitoring of these two failure mechanisms in a cracked metallic specimen repaired by a composite patch. For this purpose, the electromechanical impedance method was used to evaluate the feasibility of recognizing the type of damage at any phase...