A STUDY ON PROCESS VARIABILITY USING CUSUM AND FUZZY CONTROL CHARTS Thesis submitted to the Bharathidasan University, Tiruchirappalli in partial fulfillment of the requirements for the award of the degree of DOCTOR OF PHILOSOPHY IN STATISTICS by R. VARADHARAJAN Assistant Professor in Statistics School of Management Studies Vels University, Pallavaram, Chennai - 600117 Under the Supervision of Dr. A. PANDURANGAN Prof. and Head, Department of Computer Applications, SRM Valliammai Engineering College, Kattankulathur, Chennai- 603203 BHARATHIDASAN UNIVERSITY TIRUCHIRAPPALLI-620 024 OCTOBER – 2011 ABBREVIATIONS USED 1. ARL - Average Run Length 2. CL - Central Limit/Central Line 3. CS - Conventional Shewhart 4. CSSc - Conventional Sampling Scheme 5. DFA - Direct Fuzzy Approach 6. FIR - First Initial Response 7. FPC - Fuzzy Process Capability 8. FPCI - Fuzzy Process Capability Index 9. FSI - Fixed Sampling Interval 10. FSS - Fixed Sample Size 11. LCL - Lower Control Limit 12. LSL - Lower Specification Limits 13. MC - Markov Chain 14. MDSS - Markov Dependent Sample Size 15. MDSSc- Markov Dependent Sampling Scheme 16. PCA - Process Capability Analysis 17. PCIs - Process Capability Indices 18. SLs - Specification Limits 19. SPC - Statistical Process Control 20. SQC - Statistical Quality Control 21. SS - Standard Shewhart 22. TFN - Trapezoidal Fuzzy Number 23. TPM - Transition Probability Matrix 24. UCL - Upper Control Limit 25. USL - Upper Specification Limits 26. VSI - Variable Sampling Interval 27. VSSI - Variable Sample Size and Sampling Interval 28. VSS Variable Sample Size - ACKNOWLEDGEMENT It gives me much pleasure to record my gratitude for those who helped me in one way or other in completing this research work. I place my sincere and heartfull thanks to my Guide and Supervisor Dr.A.Pandurangan, MSc.,M.Phil.,PGDCA.,MBA.,Ph.D., Professor & Head,, Department of Computer Applications, SRM Valliammai Engineering College, Chennai, who is my source of inspiration in carrying out this research work and a role model for my career. I thank the Dr.M.Balasubramanian, B.Tech (Hons)., M.E., Ph.D., Principal of Valliammai Engineering College, Chennai for having permitted me to do my research work in the Department of Computer Applications and make use of the resources in the college. I am very much grateful to Mr.S.Stanley Sagayaraj MSc.,M.Phil.,MCA.,M.E., who has encouraged and helped me to complete the thesis. I dedicated my thesis work to my beloved parents who provide the basic of my life and supported me in every thing. I thank my wife Ms. D.Sudha, BCA., B.Ed., who has encouraged and supported me to complete the thesis. I wish to acknowledge the affection shown by my brother, R.Manikandan, B.E., my daughter V.Thanushri, and my friends who supported and encouraged me throughout my research work. R. VARADHARAJAN DECLARATION BY THE CANDIDATE I do hereby declare that this work on “A STUDY ON PROCESS VARIABILITY USING CUSUM AND FUZZY CONTROL CHARTS”, has been originally carried out by me under the guidance and supervision of Dr.A.Pandurangan, Research Advisor, working as Prof. and Head, Department of Computer Applications, SRM Valliammai Engineering College, Chennai. This work has not been submitted elsewhere either in whole or in part for the award of any other degree, diploma, associateship, fellowship or any other similar title by any University. Place: Chennai Date: (R.Varadharajan) CONTENTS Chapter No. Description Page No. 1 Introduction 1 2 Review of Literature 9 3 Standardized CUSUM Control Chart 15 4 Standardized CUSUM Median Control Chart 29 5 Fuzzy Multinomial Control Chart With Variable Sample Size 39 6 Construction of Fuzzy Control Charts Using Trapezoidal Fuzzy Number 52 7 Summary of Findings and Concluding Remarks 80 References