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profile-monitoring
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Phase-I monitoring of standard deviations in multistage linear profiles
, Article Journal of Industrial Engineering International ; Volume 14, Issue 1 , 2018 , Pages 133-142 ; 17355702 (ISSN) ; Soleimani, P ; Akhavan Niaki, T ; Atashgar, K ; Sharif University of Technology
SpringerOpen
2018
Abstract
In most modern manufacturing systems, products are often the output of some multistage processes. In these processes, the stages are dependent on each other, where the output quality of each stage depends also on the output quality of the previous stages. This property is called the cascade property. Although there are many studies in multistage process monitoring, there are fewer works on profile monitoring in multistage processes, especially on the variability monitoring of a multistage profile in Phase-I for which no research is found in the literature. In this paper, a new methodology is proposed to monitor the standard deviation involved in a simple linear profile designed in Phase I to...
On the monitoring of linear profiles in multistage processes
, Article Quality and Reliability Engineering International ; Vol. 30, Issue. 7 , November , 2014 , pp. 1035-1047 ; ISSN: 07488017 ; Niaki, S. T. A ; Soleimani, P ; Sharif University of Technology
Abstract
In most modern manufacturing systems, products are often the output of several correlated stages. Nevertheless, quality of a product or process in both single and multistage processes is usually expressed by a single quality characteristic, two or more characteristics, or profiles. Although there are many studies in univariate and multivariate-multistage process monitoring, fewer works focus on profile monitoring of multistage processes. This paper addresses the problem of monitoring a simple linear profile that is going through a multistage process in phase II. Using a first-order autoregressive correlation model, the relationship between the stages is first modeled. Then, the cascade...
Economic-statistical design of simple linear profiles with variable sampling interval
, Article Journal of Applied Statistics ; Volume 43, Issue 8 , 2016 , Pages 1400-1418 ; 02664763 (ISSN) ; Noorossana, R ; Akhavan Niaki, S. T ; Sharif University of Technology
Taylor and Francis Ltd
2016
Abstract
Control charts are statistical tools to monitor a process or a product. However, some processes cannot be controlled by monitoring a characteristic; instead, they need to be monitored using profiles. Economic-statistical design of profile monitoring means determining the parameters of a profile monitoring scheme such that total costs are minimized while statistical measures maintain proper values. While varying sampling interval usually increases the effectiveness of profile monitoring, economic-statistical design of variable sampling interval (VSI) profile monitoring is investigated in this paper. An extended Lorenzen–Vance function is used for modeling total costs in VSI model where the...
Monitoring multinomial logistic profiles in phase I using log-linear models
, Article International Journal of Quality and Reliability Management ; Volume 35, Issue 3 , 2018 , Pages 678-689 ; 0265671X (ISSN) ; Noorossana, R ; Akhavan Niaki, T ; Sharif University of Technology
Emerald Group Publishing Ltd
2018
Abstract
Purpose: The purpose of this paper is to apply Poisson generalized linear model (PGLM) with log link instead of multinomial logistic regression to monitor multinomial logistic profiles in Phase I. Hence, estimating the coefficients becomes easier and more accurate. Design/methodology/approach: Simulation technique is used to assess the performance of the proposed algorithm using four different control charts for monitoring. Findings: The proposed algorithm is faster and more accurate than the previous algorithms. Simulation results also indicate that the likelihood ratio test method is able to detect out-of-control parameters more efficiently. Originality/value: The PGLM with log link has...
, M.Sc. Thesis Sharif University of Technology ; Mahlooji, Hashem (Supervisor)
Abstract
In some statistical process control applications, quality of a process or product 1s characterized by a relationship between a response variable and one or more explanatory variables which is referred to as profile by researchers. In some applications such as calibration, this relationship is characterized by a simple linear regression. However, in some situations, more complicated models are needed. It seems that there is a little attention to monitoring of profiles with binary response variables. Furthermore, the extensive applications of binary response variables in real industrial worlds make it necessary to concentrate on this kind of profiles. In this ...
Control of Elements Ratio in Alloy Deposition System
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan (Supervisor)
Abstract
Nowadays, thin film alloy deposition has much importance. These alloys are used for various opto-electronic device applications such as liquid crystal displays, flat panel displays, plasma displays, solar cells and computer memories. Exact control of elements ratio in alloy is one of the important issues in deposition of thin film alloys. In alloy deposition with electron beam gun method from its elements, uniformity improvement of each layer is a way to maintain elements ratio in different parts of sample. This uniformity has much importance especially in optical coatings such as high quality antireflection coatings, highly selective filters and low loss reflectance coatings. In this...
The Application of Profile Monitoring in Healthcare for Disease Monitoring- case Study
, M.Sc. Thesis Sharif University of Technology ; Rafiee, Majid (Supervisor)
Abstract
Profile Monitoring is a new research topics in the field of statistical process control. In many applications of statistical quality control, sometimes quality of a process or product described by a relationship between a response variable and one or more independent variables.The researchers call this relationship profile. The study seeks to demonstrate that monitoring profiles In addition, the industry can be effective in medical field and improves control of the patient's condition by a doctor. Profiles are usually modeled with a linear regression equation, non-linear or polynomial. finally, the results of this study, using actual data, models and methods to predict and control...
Monitoring Generalized Linear Profiles Using Change-Point Approach
, M.Sc. Thesis Sharif University of Technology ; Mahlooji, Hashem (Supervisor) ; Akhavan Niaki, Taghi (Co-Advisor)
Abstract
There are many cases in industrial and non-industrial sections where the quality characteristics are in the form of profiles. A profile is the functional relationship between a response variable and one or more predictor variables used to describe the quality of a process. Profile monitoring is the implementation of statistical process control techniques for this purpose. According to the type of relationship between response variable and predictor variables, profiles are classified into many categories such as: simple linear profiles, multiple linear profiles, nonlinear profiles and generalized linear profiles. Most of the research efforts in the area of profile monitoring have been...
Monitoring autocorrelated multivariate simple linear profiles
, Article International Journal of Advanced Manufacturing Technology ; Volume 67, Issue 5-8 , 2013 , Pages 1857-1865 ; 02683768 (ISSN) ; Noorossana, R ; Niaki, S. T. A ; Sharif University of Technology
2013
Abstract
Recently, many researchers and practitioners have shown interest on profile monitoring as a relatively new subarea of statistical process control. One main reason for this interest, and perhaps a key factor for the contributions of many researchers to this field, is the various applications of profile monitoring in real life. Although one can easily encounter many univariate applications of profile monitoring in service and manufacturing environments, there exist situations where quality of a product or process needs to be modeled in multivariate terms. In this paper, we investigate monitoring of multivariate simple linear profiles in phase II when independence assumption of observations...
Phase I monitoring of simple linear profiles in multistage processes with cascade property
, Article International Journal of Advanced Manufacturing Technology ; 2016 , Pages 1-13 ; 02683768 (ISSN) ; Atashgar, K ; Akhavan Niaki, S. T ; Soleimani, P ; Sharif University of Technology
Springer London
2016
Abstract
When a multistage manufacturing process is monitored statistically, the cascade property results in a more complicated condition compared to the case when a single-stage process is controlled. The cascade property usually exists in different stages of a multistage process, where the quality of a stage influences the performance of the next stage. Moreover, sometimes the quality of a product/process is best characterized by a functional relationship. This relationship is referred to as a profile. In this paper, phase I monitoring of simple linear profile is addressed for a multistage process involving the cascade property. To aim this, the capabilities of the methods that may be used to...
A New Approach in Capability Analysis of Processes Monitored by a Simple Linear Regression Profile
, Article Quality and Reliability Engineering International ; Volume 32, Issue 1 , 2016 , Pages 209-221 ; 07488017 (ISSN) ; Noorossana, R ; Akhavan Niaki, S. T ; Sharif University of Technology
John Wiley and Sons Ltd
Abstract
In some quality control applications, quality of a product or a process can be characterized by a profile defined as a functional relationship between a response variable and one or more explanatory variables. Many researchers have contributed to the development of linear and nonlinear profiles to monitor a process or product. However, less work has been devoted to the development of process capability indices in profile monitoring to evaluate process performance with respect to specification limits. This paper presents a process capability analysis when the quality characteristic of interest is represented by a linear profile. Simulation analyses along with a real case study in leather...
Phase I monitoring of simple linear profiles in multistage processes with cascade property
, Article International Journal of Advanced Manufacturing Technology ; Volume 94, Issue 5-8 , 2018 , Pages 1745-1757 ; 02683768 (ISSN) ; Atashgar, K ; Akhavan Niaki, T ; Soleimani, P ; Sharif University of Technology
Springer London
2018
Abstract
When a multistage manufacturing process is monitored statistically, the cascade property results in a more complicated condition compared to the case when a single-stage process is controlled. The cascade property usually exists in different stages of a multistage process, where the quality of a stage influences the performance of the next stage. Moreover, sometimes the quality of a product/process is best characterized by a functional relationship. This relationship is referred to as a profile. In this paper, phase I monitoring of simple linear profile is addressed for a multistage process involving the cascade property. To aim this, the capabilities of the methods that may be used to...
Application of the generalized linear models to represent profiles
, Article 35th International Conference on Computers and Industrial Engineering, ICC and IE 2005, Istanbul, 19 June 2005 through 22 June 2005 ; 2005 , Pages 1-6 ; 9755612653 (ISBN); 9789755612652 (ISBN) ; Akhavan Niaki, S. T ; Arkat, J ; Sharif University of Technology
2005
Abstract
Statistical process control methods for monitoring processes with multivariate measurements in both the product quality variable space and process variable space are considered in this paper. Some processes, however, are better characterized by a profile or a function of quality variables. For each profile, we assume that a collection of data on the response variable along with the values of the corresponding quality variables is measured. While the linear function is the simplest, it occurs frequently that many of the nonlinear functions may be transferred to linear functions easily. This paper proposes a control chart based on the generalized linear test (GLT) to monitor coefficients of...
Phase II monitoring of binary response profiles
, Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 2238-2246 ; 10263098 (ISSN) ; Khedmati, M ; Mahlooji, H ; Sharif University of Technology
Sharif University of Technology
2013
Abstract
In many situations, the quality of a process can be characterized better by a relationship, known as a profile, between a response variable and one or more predictors. Almost all research efforts assume that response variable is continuous and follows a normal distribution, while there are instances in which the response is a binary variable, and methods such as logistic regression are commonly used. In this paper, four control schemes namely Hotelling T2, MEWMA, Likelihood Ratio Test (LRT) and LRT/EWMA are proposed to monitor binary response profiles in phase II. The performance of the proposed control charts is evaluated and compared by simulation experiments for different shift values in...
A generalized linear Statistical model approach to monitor profiles
, Article International Journal of Engineering, Transactions A: Basics ; Volume 20, Issue 3 , 2007 , Pages 233-242 ; 17281431 (ISSN) ; Abbasi, B ; Arkat, J ; Sharif University of Technology
Materials and Energy Research Center
2007
Abstract
Statistical process control methods for monitoring processes with univariate or multivariate measurements are used widely when the quality variables fit to known probability distributions. Some processes, however, are better characterized by a profile or a function of quality variables. For each profile, it is assumed that a collection of data on the response variable along with the values of the corresponding quality variables is measured. While the linear function is the simplest, it occurs frequently that many of the nonlinear functions may be transferred to linear functions easily. This paper proposes a control chart based on the generalized linear test (GLT) to monitor coefficients of...
Risk-adjusted Profile Monitoring in Dependent Multi-stage Processes in Healthcare Systems
, M.Sc. Thesis Sharif University of Technology ; Akhavan Niaki, Taghi (Supervisor)
Abstract
Control chart is one of the most powerful tools in statistical process control (SPC). This tool has been widely used in industrial schemes; however, in recent years, it has become widespread in health care studies as well. Most of these studies are dealing with monitoring qualitative variables in one-stage processes. This research presents a new mechanism for monitoring medical processes, by modelling the bone marrow transplant surgery as a dependent multi-stage process into a multiple profile. In this mechanism, the characteristics which will be monitored are quantitative, and the cascade property between stages is considered. Moreover, risk adjustment methods have been used due to the...
Economic and economic-statistical designs of phase II profile monitoring
, Article Quality and Reliability Engineering International ; Vol. 30, issue. 5 , July , 2014 , pp. 645-655 ; ISSN: 07488017 ; Niaki, S. T. A ; Ershadi, M. J ; Sharif University of Technology
Abstract
In economic design of profiles, parameters of a profile are determined such that the total implementation cost is minimized. These parameters consist of the number of set points, n, the interval between two successive sampling, h, and the parameters of a control chart used for monitoring. In this paper, the Lorenzen-Vance cost function is extended to model the costs associated with implementing profiles. The in-control and the out-of-control average run lengths, ARL0 and ARL1, respectively, are used as two statistical measures to evaluate the statistical performances of the proposed model. A genetic algorithm (GA) is developed for solving both the economic and the economic-statistical...
Statistical monitoring of nominal logistic profiles in phase II
, Article Communications in Statistics - Theory and Methods ; Volume 44, Issue 13 , 2015 , Pages 2689-2704 ; 03610926 (ISSN) ; Izadbakhsh, H ; Aminnayer, M ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
Statistical analysis of profile monitoring, a relatively new sub-area of statistical process control due to its applications in different industries, have urged researchers and practitioners to contribute to the developments of new monitoring methods. A statistical profile is a relationship between a quality characteristic (a response) and one or more independent variables to characterize quality of a process or a product. In this article, statistical profiles based on nominal responses are studied, where logistic regression is used to model the responses. Three approaches including likelihood ratio test (LRT), multivariate exponentially weighted moving average (MEWMA), and support vector...
A change point method for monitoring generalized linear profiles in phase I
, Article Quality and Reliability Engineering International ; Volume 31, Issue 8 , 2015 , Pages 1367-1381 ; 07488017 (ISSN) ; Mahlooji, H ; Yeh, A. B ; Zou, C ; Sharif University of Technology
Abstract
The Phase I applications of the statistical profile monitoring have recently been extended to the case when the response variable is binary. We are motivated to undertake the current research in an attempt to try to provide a unified framework for the Phase I control in the context of statistical profile monitoring that can be used to tackle a large class of response variables, such as continuous, count, or categorical response variables. The unified framework is essentially based on applying the change point model to the class of generalized linear models. The proposed Phase I control chart is assessed and compared with the existing charts under binomial and Poisson profiles. Some...
Phase-I monitoring of general linear profiles in multistage processes
, Article Communications in Statistics: Simulation and Computation ; Volume 46, Issue 6 , 2017 , Pages 4465-4489 ; 03610918 (ISSN) ; Akhavan Niaki, S. T ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
In this article, the general linear profile-monitoring problem in multistage processes is addressed. An approach based on the U statistic is first proposed to remove the effect of the cascade property in multistage processes. Then, the T2 chart and a likelihood ratio test (LRT)-based scheme on the adjusted parameters are constructed for Phase-I monitoring of the parameters of general linear profiles in each stage. Using simulation experiments, the performance of the proposed methods is evaluated and compared in terms of the signal probability for both weak and strong autocorrelations, for processes with two and three stages, as well as for two sample sizes. According to the results, the...