Pub Date : 2017-12-23DOI: 10.1504/IJQET.2017.10009790
F. Ali, Amran Ahmed
This paper presents Six Sigma evaluation based on process capability with -X control chart to reduce variations in the oil density characteristics in an oil refinery process in Aden, Yemen. Twenty-five oil density samples with normal distribution were randomly collected, and each sample consisted of four items. Analysis indicated that the levels of sigma employed in Aden refinery are less than 3 σ. The results of this study suggested that the -X chart based on six sigma estimation method is significant to reduce variance in the oil density characteristic. In addition, the sigma levels increase when the process capability increases. Thus, the increment in sigma levels leads to improvements in the performance of the process refinery of oil density characteristic. Finally, this paper provides the necessary fundamentals and knowledge for quality control researchers and engineers to reduce variances by using Six Sigma.
{"title":"Six Sigma evaluation using process capability and -X control chart for reducing variance in oil density characteristic: a study in Yemen","authors":"F. Ali, Amran Ahmed","doi":"10.1504/IJQET.2017.10009790","DOIUrl":"https://doi.org/10.1504/IJQET.2017.10009790","url":null,"abstract":"This paper presents Six Sigma evaluation based on process capability with -X control chart to reduce variations in the oil density characteristics in an oil refinery process in Aden, Yemen. Twenty-five oil density samples with normal distribution were randomly collected, and each sample consisted of four items. Analysis indicated that the levels of sigma employed in Aden refinery are less than 3 σ. The results of this study suggested that the -X chart based on six sigma estimation method is significant to reduce variance in the oil density characteristic. In addition, the sigma levels increase when the process capability increases. Thus, the increment in sigma levels leads to improvements in the performance of the process refinery of oil density characteristic. Finally, this paper provides the necessary fundamentals and knowledge for quality control researchers and engineers to reduce variances by using Six Sigma.","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"186"},"PeriodicalIF":0.0,"publicationDate":"2017-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46924756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-23DOI: 10.1504/IJQET.2017.10009786
Kadri Ouahab, L. Mouss, Adel Abdelhadi
This paper addresses the problem of fault diagnosis from observed data containing missing values amongst the inputs. In order to provide good classification accuracy for the decision function, a novel approach based on support vector machine and extreme learning machine is developed. SVM mixture model is used to model the data distribution, which is adapted to handle missing values, while extreme learning machine enables to devise a multiple imputation strategy for final estimation. In order to prove the efficiency of our proposed method, we have developed the classifier using the condition monitoring observations from milk pasteurisation data. The experiments show that the proposed algorithm gives improved results compared to recent methods, essentially if the number of missing data is significant. The results show that our approach can perfectly detect dysfunction, identify the fault, and is strong in unsupervised process monitoring.
{"title":"Fault diagnosis for a milk pasteurisation plant with missing data","authors":"Kadri Ouahab, L. Mouss, Adel Abdelhadi","doi":"10.1504/IJQET.2017.10009786","DOIUrl":"https://doi.org/10.1504/IJQET.2017.10009786","url":null,"abstract":"This paper addresses the problem of fault diagnosis from observed data containing missing values amongst the inputs. In order to provide good classification accuracy for the decision function, a novel approach based on support vector machine and extreme learning machine is developed. SVM mixture model is used to model the data distribution, which is adapted to handle missing values, while extreme learning machine enables to devise a multiple imputation strategy for final estimation. In order to prove the efficiency of our proposed method, we have developed the classifier using the condition monitoring observations from milk pasteurisation data. The experiments show that the proposed algorithm gives improved results compared to recent methods, essentially if the number of missing data is significant. The results show that our approach can perfectly detect dysfunction, identify the fault, and is strong in unsupervised process monitoring.","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"123"},"PeriodicalIF":0.0,"publicationDate":"2017-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49520008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-23DOI: 10.1504/IJQET.2017.10009783
A. Badiru
In the pursuit of better quality under the spirit of continuous improvement, it is appropriate to inquire about the potential limit of quality. Using quality engineering and technology tools and techniques, can we continue to improve quality indefinitely, inching toward the limit of quality ever so infinitesimally? This paper presents a postulation of an asymptomatic approach to the limit of quality based on the mathematical reasoning of pi. While there is no mathematical correlation of pi to the physical quality of a product, it is interesting and inspirational to conduct research on the move toward the best possible point on the quality curve. In this regard, the motivational question is 'what is the limit of quality?' The methodology of this paper suggests some interesting analogies.
{"title":"Quality Insights: A pi tail mathematical postulation of the limit of quality","authors":"A. Badiru","doi":"10.1504/IJQET.2017.10009783","DOIUrl":"https://doi.org/10.1504/IJQET.2017.10009783","url":null,"abstract":"In the pursuit of better quality under the spirit of continuous improvement, it is appropriate to inquire about the potential limit of quality. Using quality engineering and technology tools and techniques, can we continue to improve quality indefinitely, inching toward the limit of quality ever so infinitesimally? This paper presents a postulation of an asymptomatic approach to the limit of quality based on the mathematical reasoning of pi. While there is no mathematical correlation of pi to the physical quality of a product, it is interesting and inspirational to conduct research on the move toward the best possible point on the quality curve. In this regard, the motivational question is 'what is the limit of quality?' The methodology of this paper suggests some interesting analogies.","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"210"},"PeriodicalIF":0.0,"publicationDate":"2017-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48329288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.1504/ijqet.2017.10015602
Antonio Jesús Sanhouse García, J. R. Medina, Abraham E. Rodríguez Mata, J. Peraza, Edith Padilla Gasca, Yaneth A. Bustos Terrones
{"title":"Optimisation of food processing with multiple quality characteristics using desirability function","authors":"Antonio Jesús Sanhouse García, J. R. Medina, Abraham E. Rodríguez Mata, J. Peraza, Edith Padilla Gasca, Yaneth A. Bustos Terrones","doi":"10.1504/ijqet.2017.10015602","DOIUrl":"https://doi.org/10.1504/ijqet.2017.10015602","url":null,"abstract":"","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"302"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66692826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.1504/IJQET.2017.10009738
Farhad Imani, Ki-Hwan G. Bae
Lifetime warranty is a type of long-term assurance that is now ubiquitous. With a long period of coverage, however, the expected number of failures and the associated costs are likely to add up. Hence, maintenance policies over a lifetime warranty can have a substantial impact on warranty servicing costs. Maintenance policies impose additional costs and would be worthy only if the reduction amount in total costs due to maintenance is greater than maintenance costs. The focus of this paper is on modelling preventive maintenance during a lifetime warranty in order to derive optimal maintenance policy and optimal level of repair based on the structures of a cost function and a failure rate function. Our investigation demonstrates that the optimal strategy for preventive maintenance can be achieved by considering minor repairs during early ages and marginal repairs near the end of a product life. Numerical examples are provided to evaluate our developed models and support the corresponding results.
{"title":"Preventive maintenance modelling in lifetime warranty","authors":"Farhad Imani, Ki-Hwan G. Bae","doi":"10.1504/IJQET.2017.10009738","DOIUrl":"https://doi.org/10.1504/IJQET.2017.10009738","url":null,"abstract":"Lifetime warranty is a type of long-term assurance that is now ubiquitous. With a long period of coverage, however, the expected number of failures and the associated costs are likely to add up. Hence, maintenance policies over a lifetime warranty can have a substantial impact on warranty servicing costs. Maintenance policies impose additional costs and would be worthy only if the reduction amount in total costs due to maintenance is greater than maintenance costs. The focus of this paper is on modelling preventive maintenance during a lifetime warranty in order to derive optimal maintenance policy and optimal level of repair based on the structures of a cost function and a failure rate function. Our investigation demonstrates that the optimal strategy for preventive maintenance can be achieved by considering minor repairs during early ages and marginal repairs near the end of a product life. Numerical examples are provided to evaluate our developed models and support the corresponding results.","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"249"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66692714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.1504/IJQET.2017.10015599
J. Malela‐Majika, E. Rapoo
Control chart is one of the most important tools used in statistical process control and monitoring (SPCM) to detect changes in quality characteristics. This paper investigates the performance of the improved modified distribution-free synthetic and runs-rules charts combined with a Mann-Whitney (MW) chart, in terms of the average run length (ARL) and median run length (MRL) through intensive simulation. It is observed that the newly proposed improved modified synthetic and runs-rules MW charts present very attractive run-length properties and outperform the competing charts under non-normal underlying distributions. Numerical examples are given as illustration of the design and implementation of the proposed charts.
{"title":"Distribution-free synthetic and runs-rules control charts combined with a Mann-Whitney chart","authors":"J. Malela‐Majika, E. Rapoo","doi":"10.1504/IJQET.2017.10015599","DOIUrl":"https://doi.org/10.1504/IJQET.2017.10015599","url":null,"abstract":"Control chart is one of the most important tools used in statistical process control and monitoring (SPCM) to detect changes in quality characteristics. This paper investigates the performance of the improved modified distribution-free synthetic and runs-rules charts combined with a Mann-Whitney (MW) chart, in terms of the average run length (ARL) and median run length (MRL) through intensive simulation. It is observed that the newly proposed improved modified synthetic and runs-rules MW charts present very attractive run-length properties and outperform the competing charts under non-normal underlying distributions. Numerical examples are given as illustration of the design and implementation of the proposed charts.","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"219"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66692754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.1504/IJQET.2017.10015600
Anintaya Khamkanya, B. Cho, P. Goethals
One of the most popular quality engineering tools is the process capability index (PCI), which relates the allowable spread of a process defined by engineering specifications to the natural spread of a process. The traditional PCI does not account for the loss in quality when product characteristics fail to achieve their process target value. This research, in contrast, proposes indices, namely posterior PCIs, that consider the underlying result of observations after inspection. Utilising a truncated distribution as the basis for measurement along with a target-based quality loss function for capability analyses, several posterior indices are developed in this paper. A simulation technique is implemented to compare the proposed posterior PCIs with traditional measures. Finally, the confidence interval approximations for the posterior PCIs are derived. Our results suggest using the proposed posterior indices for capability analyses when industrial processes require that non-conforming products be scrapped prior to shipping to the customer.
{"title":"The development of target-based posterior process capability indices and confidence intervals","authors":"Anintaya Khamkanya, B. Cho, P. Goethals","doi":"10.1504/IJQET.2017.10015600","DOIUrl":"https://doi.org/10.1504/IJQET.2017.10015600","url":null,"abstract":"One of the most popular quality engineering tools is the process capability index (PCI), which relates the allowable spread of a process defined by engineering specifications to the natural spread of a process. The traditional PCI does not account for the loss in quality when product characteristics fail to achieve their process target value. This research, in contrast, proposes indices, namely posterior PCIs, that consider the underlying result of observations after inspection. Utilising a truncated distribution as the basis for measurement along with a target-based quality loss function for capability analyses, several posterior indices are developed in this paper. A simulation technique is implemented to compare the proposed posterior PCIs with traditional measures. Finally, the confidence interval approximations for the posterior PCIs are derived. Our results suggest using the proposed posterior indices for capability analyses when industrial processes require that non-conforming products be scrapped prior to shipping to the customer.","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"269"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66692810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-01DOI: 10.1504/IJQET.2016.081638
M. Tavakoli, R. Pourtaheri, M. B. Moghadam
Recent studies on multivariate control charts are based on Hotelling's T2 control chart. Due to the fact that the Bayesian control charts in a univariate can be effective on performance of control charts, this paper has proposed the multivariate Bayesian control chart based on economic and economic-statistical design. As finding distribution of Bayesian statistic is too difficult, the Monte Carlo method has been employed in order to determine design optimum parameters (sample size, sampling interval and control limit). Also, artificial bee colony (ABC) algorithm has been applied to search for the optimal design parameters. Ultimately, the performance of the proposed control chart and Hotelling's T2 were compared for more in-depth investigation.
{"title":"Multivariate Bayesian control chart based on economic and economic-statistical design using Monte Carlo method and ABC algorithm","authors":"M. Tavakoli, R. Pourtaheri, M. B. Moghadam","doi":"10.1504/IJQET.2016.081638","DOIUrl":"https://doi.org/10.1504/IJQET.2016.081638","url":null,"abstract":"Recent studies on multivariate control charts are based on Hotelling's T2 control chart. Due to the fact that the Bayesian control charts in a univariate can be effective on performance of control charts, this paper has proposed the multivariate Bayesian control chart based on economic and economic-statistical design. As finding distribution of Bayesian statistic is too difficult, the Monte Carlo method has been employed in order to determine design optimum parameters (sample size, sampling interval and control limit). Also, artificial bee colony (ABC) algorithm has been applied to search for the optimal design parameters. Ultimately, the performance of the proposed control chart and Hotelling's T2 were compared for more in-depth investigation.","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"67"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1504/IJQET.2016.081638","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66692637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-01DOI: 10.1504/IJQET.2016.081632
A. Badiru
The fully-burdened cost of quality management programs must be viewed from a systems perspective with respect to the value impacted on the organisation. What appears to be cost-effective or cheap in the present scenario may proof to be costly (or even disastrous) in the long run of market share with respect to customer perception. This paper presents an application of the equity breakeven point technique for graphical analysis of quality investments. The mathematical derivation of the equity breakeven point indicates the time when the unpaid balance on a capital investment is equal to the cumulative equity in the investment, thereby providing an a-priori insight into how long it might take to retire an investment loan on the strength of the accrued equity. This type of knowledge is useful for negotiating the terms of acquiring and/or managing large quality-oriented projects, with expected long-term impacts.
{"title":"Visualising the Cost of Quality Investment Using Equity Breakeven Point","authors":"A. Badiru","doi":"10.1504/IJQET.2016.081632","DOIUrl":"https://doi.org/10.1504/IJQET.2016.081632","url":null,"abstract":"The fully-burdened cost of quality management programs must be viewed from a systems perspective with respect to the value impacted on the organisation. What appears to be cost-effective or cheap in the present scenario may proof to be costly (or even disastrous) in the long run of market share with respect to customer perception. This paper presents an application of the equity breakeven point technique for graphical analysis of quality investments. The mathematical derivation of the equity breakeven point indicates the time when the unpaid balance on a capital investment is equal to the cumulative equity in the investment, thereby providing an a-priori insight into how long it might take to retire an investment loan on the strength of the accrued equity. This type of knowledge is useful for negotiating the terms of acquiring and/or managing large quality-oriented projects, with expected long-term impacts.","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"40"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1504/IJQET.2016.081632","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66692573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-01DOI: 10.1504/IJQET.2016.081626
A. Heydari, M. B. Moghadam, F. Eskandari
The optimal values of economic and economic statistical designs of -X control charts are influenced by a model used for distribution of occurring time of assignable causes or shock model. So far, only a small number of failure time distributions such as exponential, gamma and Weibull with fixed or increasing hazard rates have been used as shock models. However, from both theoretical and practical aspects, processes under study may not have fixed or increasing hazard rates. A proper alternative is the Burr XII distribution which its hazard rate can be fixed, increasing, decreasing, single mode or even U-shaped. In this research paper, economic and economic statistical designs of -X control charts under the Burr XII shock models were proposed and constructed. The obtained design models have been implemented by a numerical example and a sensitivity analysis were conducted.
{"title":"Economic and economic statistical designs of -X control charts under Burr XII shock model","authors":"A. Heydari, M. B. Moghadam, F. Eskandari","doi":"10.1504/IJQET.2016.081626","DOIUrl":"https://doi.org/10.1504/IJQET.2016.081626","url":null,"abstract":"The optimal values of economic and economic statistical designs of -X control charts are influenced by a model used for distribution of occurring time of assignable causes or shock model. So far, only a small number of failure time distributions such as exponential, gamma and Weibull with fixed or increasing hazard rates have been used as shock models. However, from both theoretical and practical aspects, processes under study may not have fixed or increasing hazard rates. A proper alternative is the Burr XII distribution which its hazard rate can be fixed, increasing, decreasing, single mode or even U-shaped. In this research paper, economic and economic statistical designs of -X control charts under the Burr XII shock models were proposed and constructed. The obtained design models have been implemented by a numerical example and a sensitivity analysis were conducted.","PeriodicalId":38209,"journal":{"name":"International Journal of Quality Engineering and Technology","volume":"6 1","pages":"1"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1504/IJQET.2016.081626","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66692508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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