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حرية الوصول المقاله
1 - ارائه نمودار کنترلی فراگیر برای مانیتورینگ پروفایل‌های خطی و غیرخطی با استفاده از آنالیز داده‌های تابعی
مهراب بحری عبداله هادی وینچهدر این مقاله پروفایل‌ها به عنوان متغیرهای تابعی در نظر گرفته شده و دو نمودار کنترلی برای مانیتورینگ آنها در فاز II پیشنهاد شده است. به‌کارگیری مدل تابعی به دلیل منطبق بودن بر ماهیت پروفایل‌ها در دنیای واقعی، باعث می‌شود که نمودارهای کنترلی پیشنهادی که به کمک تکنیک‌های أکثردر این مقاله پروفایل‌ها به عنوان متغیرهای تابعی در نظر گرفته شده و دو نمودار کنترلی برای مانیتورینگ آنها در فاز II پیشنهاد شده است. به‌کارگیری مدل تابعی به دلیل منطبق بودن بر ماهیت پروفایل‌ها در دنیای واقعی، باعث می‌شود که نمودارهای کنترلی پیشنهادی که به کمک تکنیک‌های آنالیز داده‌های تابعی بدست آمده، دارای ویژگی‌های مطلوبی باشند از جمله: سادگی محاسباتی، قابلیت بکارگیری یکسان برای پروفایل‌های گوناگون (خطی و غیرخطی در شکل‌های مختلف) و پذیرش شکل‌های پیچیده خودهمبستگی درون پروفایلی. این ویژگی‌ها متمایز کننده مدل تابعی نسبت به مدل‌های رگرسیونی است که در پروفایل مانیتورینگ متداول‌اند. شبیه‌سازی کامپیوتری انجام شده نشان می‌دهد که در حالت‌های مختلف نمودارهای کنترلی پیشنهادی نسبت به سایر روش‌ها متوسط طول دنباله کوتاه‌تری دارند که نشان دهنده عملکرد مطلوب رویکرد تابعی اتخاذ شده است؛ بعلاوه این که در تعدادی از حالات غیرخطی با خودهمبستگی پیچیده، سایر روش‌ها به کلی از کار افتاده و تنها نمودارهای کنترلی پیشنهادی این تحقیق قادر به تشخیص انحراف بوجود آمده هستند و حتی در این حالات نیز متوسط طول دنباله این نمودارهای کنترلی بسیار مطلوب می‌باشد. تفاصيل المقالة -
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2 - بررسی کاربرد فرایند کنترل کیفیت آماری در شرکت صنایع چوب کیش
هیرسا جویا اردکانی بهزاد بازیار امیر هومن حمصی مرتضی خاکزاربفروئیدر این پژوهش، کاربرد فرایند کنترل آماری کیفیت در شرکت صنایع چوب کیش مورد بررسی قرار گرفت. فرایند کنترل کیفیت آماری، شامل انواع نمودارهای کنترل و طرح های نمونه گیری به منظور پذیرش می باشد. در این مطالعه، با استفاده از جداول استاندارد بازرسی، مشخصه های کمّی و کیفی مواد او أکثردر این پژوهش، کاربرد فرایند کنترل آماری کیفیت در شرکت صنایع چوب کیش مورد بررسی قرار گرفت. فرایند کنترل کیفیت آماری، شامل انواع نمودارهای کنترل و طرح های نمونه گیری به منظور پذیرش می باشد. در این مطالعه، با استفاده از جداول استاندارد بازرسی، مشخصه های کمّی و کیفی مواد اولیه و محصولات در جریان ساخت، بررسی و همچنین نمودارهای کنترل X ̅ و R، P و U برای فرایندهای شیارزنی، سوراخ کاری، روکش کاری و نوارکاری طراحی شدند. در قسمت مواد اولیه و محصولات در جریان ساخت، بهرهای مربوط به ام دی اف 16 میلیمتر، روکش اچ پی ال، نوارلبه ای بی اس خریداری شده و فاصله سوراخ دوبل از لبه قطعه از نظر مشخصه کمّی با استفاده از جداول استاندارد نظامی 414 بررسی شدند. بهر تخته خرده چوب روکش دار خریداری شده و صحّت نوار لبه در قطعات کف کابینت از نظر مشخصه کیفی با استفاده از جداول استاندارد نظامی 105E مورد بازرسی قرار گرفت. همه موارد با سطح کیفیت قابل قبول شرکت مطابقت داشتند. قرار گرفتن نقاط بین حدود کنترل در نمودارهای کنترل بیانگر این است که هر یک از فرایندها در مقطع زمانی انجام مطالعه تحت کنترل بوده و می توان از آنها به منظور کنترل آینده فرایند استفاده کرد. با محاسبه شاخص قابلیّت فرایند مشخص شد که فرایندهای شیارزنی و سوراخ کاری قابلیّت بسیار بالایی داشته و در نتیجه درصد ضایعات در این دو فرایند بسیار پایین است. تفاصيل المقالة -
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3 - Performance Monitoring over Time by Data Envelopment Analysis and Statistical Control Charts (A Real Maintenance Unit as Case Study)
Hamidreza Izadbakhsh Ali MoradiData envelopment analysis (DEA) is a well-known approach for measuring performance of units in the presence of multiple input and output variables. Statistical control charts, on the other hand, have been developed for monitoring performance over the time and for distin أکثرData envelopment analysis (DEA) is a well-known approach for measuring performance of units in the presence of multiple input and output variables. Statistical control charts, on the other hand, have been developed for monitoring performance over the time and for distinguishing between in-control and out-control states. Using advantages of these approaches in this paper, an integrated model is proposed for measuring and controlling performance of unit(s) over the time. A real maintenance unit and its data are used as a case study for better understanding of the proposed model. تفاصيل المقالة -
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4 - Efficient Selection of Design Parameters in Multi-Objective Economic-Statistical Model of Attribute C Control Chart
S. Jafarian-Namin A. Amiri E. NajafiControl chart is the most well-known chart to monitor the number of nonconformities per inspection unit where each sample consists of constant size. Generally, the design of a control chart requires determination of sample size, sampling interval, and control limits wid أکثرControl chart is the most well-known chart to monitor the number of nonconformities per inspection unit where each sample consists of constant size. Generally, the design of a control chart requires determination of sample size, sampling interval, and control limits width. Optimally selecting these parameters depends on several process parameters, which have been considered from statistical and/or economic aspects in the literature. This study presents a multi-objective economic-statistical design (MOESD) of the C control chart. An algorithm using data envelopment analysis (DEA) is employed to solve this model. A numerical example is used to illustrate the algorithm procedure. تفاصيل المقالة -
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5 - Construction of α-cut fuzzy X control charts based on standard deviation and range using fuzzy triangular numbers
Ezzatollah Balouyi JamkhanehControl charts are one of the most important tools in statistical process control that lead to improve quality processes and ensure required quality levels. In traditional control charts, all data should be exactly known, whereas there are many quality characteristics t أکثرControl charts are one of the most important tools in statistical process control that lead to improve quality processes and ensure required quality levels. In traditional control charts, all data should be exactly known, whereas there are many quality characteristics that cannot be expressed in numerical scale, such as characteristics for appearance, softness, and color. Fuzzy sets theory is a powerful mathematical approach to analyze uncertainty, ambiguous and incomplete that can linguistically define data in these situations. Fuzzy control charts have been extended by converting the fuzzy sets associated with linguistic or uncertain values into scalars regarded as representative values. In this paper, we study two different approaches to construct X ̅ control chart, when the observations are fuzzy number. Two methods of defuzzification for calculating the value representing sample means and for determining the control chart limits are presented. In the second approach α-cut control chart for variable are developed using upper control limits and lower control limits. The article also presents a fuzzy decision for in control or out of control of the process, in which membership degrees of in and out of control states of process mean is computed. تفاصيل المقالة -
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6 - کاربرد روش‌های بازنمونه‌گیری در نمودارهای کنترل جمع تجمعی چندمتغیره
Abdol-Rasoul Mostajeran Amirhoussin Aghajaniیکی از ابزارهای مهم کنترل فرآیند، نمودارهای کنترل هستند. نمودارهای کنترل شوهارت فقط از اطلاعات آخرین نمونه استفاده می‌کنند، لذا فاقد حافظه هستند و قادر به تشخیص انحرافات کوچک نیستند. همچنین، نمودارهای کنترل شوهارت چندمتغیره اغلب بر اساس فرض نرمال بودن مشاهدات به کار می أکثریکی از ابزارهای مهم کنترل فرآیند، نمودارهای کنترل هستند. نمودارهای کنترل شوهارت فقط از اطلاعات آخرین نمونه استفاده می‌کنند، لذا فاقد حافظه هستند و قادر به تشخیص انحرافات کوچک نیستند. همچنین، نمودارهای کنترل شوهارت چندمتغیره اغلب بر اساس فرض نرمال بودن مشاهدات به کار می‌رود که در عمل ممکن است برقرار نباشد. نمودارهای کنترل جمع تجمعی چندمتغیره (mcusum) یکی از پرکاربردترین ابزارهای کنترل فرآیند آماری چندمتغیره در کنترل کیفیت می‌باشد. نمودار کنترل جمع تجمعی چندمتغیره از عیوب نمودارهای شوهارت مبرا است. این نمودار دارای حافظه است و نسبت به انحرافات کوچک حساس است. تعیین توزیع دقیق و حدی آماره نمودار کنترل جمع تجمعی برداری چندمتغیره به دلیل ساختار آن حتی تحت فرض نرمال بودن توزیع داده‌ها مشکل است و به همین علت از طریق شبیه‌سازی، توزیع آن را تعیین می‌کنند. نمودارهای کنترل بوت‌استرپ بدون نیاز به معلوم بودن توزیع داده‌ها، بر اساس باز نمونه‌گیری از مشاهدات (داده‌های اصلی) است. در این مقاله برای اولین بار کاربرد روش‌های باز نمونه‌گیری در نمودارهای کنترل جمع تجمعی چندمتغیره ارائه می‌گردد. چهار الگوریتم متفاوت بازنمونه‌گیری معرفی شده است. الگوریتم‌ها با استفاده از معیار ARL0 در مطالعات شبیه‌سازی مقایسه شده اند. کد برنامه‌های شبیه‌سازی در برنامه R نوشته و اجرا گردیده است. در نهایت یک مثال واقعی که مطالعه موردی در کارخانه قند شهر اصفهان بوده، ارائه شده است. تفاصيل المقالة -
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7 - ارزیابی کیفیت فرایند تولید با رویکرد نمودارهای کنترلی نوع X-R و قابلیت فرایند تولید( مطالعه موردی شرکت بین المللی سیمان ایلام)
Mohammad Bagher Rasouleh Vandi Mehdi Zangenehهدف این مقاله ارزیابی کیفیت فرایند تولید با رویکرد نمودارهای کنترلی نوع X-R و قابلیت فرایند تولید می باشد. جامعه آماری تعداد 170نفرازمدیران ارشد، میانی و کاربران بخش کنترل کیفیت، پرسنل بخش تولید و کارکنان بخش پشتیبانی تولید شرکت بین‌المللی سیمان ایلام می‌باشد، که تعداد أکثرهدف این مقاله ارزیابی کیفیت فرایند تولید با رویکرد نمودارهای کنترلی نوع X-R و قابلیت فرایند تولید می باشد. جامعه آماری تعداد 170نفرازمدیران ارشد، میانی و کاربران بخش کنترل کیفیت، پرسنل بخش تولید و کارکنان بخش پشتیبانی تولید شرکت بین‌المللی سیمان ایلام می‌باشد، که تعداد 118 نفر به عنوان نمونه و با استفاده از فرمول کوکران انتخاب شده اند. برای دست یابی به این هدف از رگرسیون خطی چند گانه استفاده شده است، که داده های مورد نیاز آن با استفاده از یک پرسشنامه استاندارد شده جمع آوری و سپس با استفاده از نرم افزار SPSS مورد تجزیه و تحلیل قرار گرفت و معلوم شد که نوع مواد اولیه و تجهیزات تولید این نمودارها را تحت تاثیر قرار می دهد، اما اپراتورها و تکنسین های نزدیک به فرایند تولید نمی توانند این نمودارها را تحت تاثیر قراردهند. همچنین نتایج نشان داد که مشتریان و بازار فروش، شرایط عملیاتی فرایند تولید و نمونه گیری نیز بر روی قابلیت فرایند تولید تاثیر گذار هستند. تفاصيل المقالة -
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8 - A New Method for Diagnosing Patients Suspected of Bone Marrow Metastasis in the Presence of Outliers
Mahmood Shahrabi Amirhossein Amiri Hamidreza Saligheh Rad Sedigheh GhofraniIn recent years, medical images have played an essential role in diagnosis, treatment, and training areas. Thus, any advancement in this field can help doctors in diagnosing. On the other hand, statistical process control (SPC) is now widely used in monitoring healthcar أکثرIn recent years, medical images have played an essential role in diagnosis, treatment, and training areas. Thus, any advancement in this field can help doctors in diagnosing. On the other hand, statistical process control (SPC) is now widely used in monitoring healthcare processes. In this research, using the image processing techniques and feature extraction methods (two-dimensional discrete wavelet), we propose some multivariate control charts to diagnose the type of bone marrow of the patients suspected of bone marrow metastasis in the pelvic region with early breast tumors. For this, 76 features (energy and histogram of oriented gradient) are extracted from the image. Next, using the GA, six features are selected and constitute a feature vector. Based on the feature vector, Hotelling’s T2 multivariate control charts are developed. Moreover, considering the high sensitivity of the classic estimators to outliers and contaminated data, we provide a robust Hotelling’s T2 control chart. Finally, we compare the ARL performance of the robust and the classic Hotelling’s T2 control charts in Phase II in the presence of local outliers in the Phase I data. The results confirmed the superiority of the robust version. تفاصيل المقالة -
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9 - A Review and Evaluation of Statistical Process Control Methods inMonitoring Process Mean and Variance Simultaneously
Ahmad Ostadsharifmemar Seyed Taghi Akhavan NiakiIn this paper, first the available single charting methods, which have been proposed to detect simultaneous shifts in a single process mean and variance, are reviewed. Then, by designing proper simulation studies these methods are evaluated in terms of in-control and ou أکثرIn this paper, first the available single charting methods, which have been proposed to detect simultaneous shifts in a single process mean and variance, are reviewed. Then, by designing proper simulation studies these methods are evaluated in terms of in-control and out-ofcontrol average run length criteria (ARL). The results of these simulation experiments show that the EWMA and EWMS methods are quite capable to detect large shifts in the means and variances. However, while the two EWMV procedures under study do not perform well, the Max-Min EWMA and Max-EWMA perform very well in all scenarios of mean and variance shifts. تفاصيل المقالة -
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10 - Change Point Estimation of a Process Variance with a Linear TrendDisturbance
Rassoul Noorossana Majeed HeydariWhen a change occurs in a process, one expects to receive a signal from a control chart as quickly as possible. Upon the receipt of signal from the control chart a search for identifying the source of disturbance begins. However, searching for assignable cause around th أکثرWhen a change occurs in a process, one expects to receive a signal from a control chart as quickly as possible. Upon the receipt of signal from the control chart a search for identifying the source of disturbance begins. However, searching for assignable cause around the signal time, due to the fact that the disturbance may have manifested itself into the rocess sometimes back, may not always lead to successful identification of assignable cause(s). If process engineers could identify the change point, i.e. the time when the disturbance first manifested itself into the process, then corrective actions could be directed towards effective elimination of the source of disturbance. In this paper we develop a maximum likelihood estimator (MLE) for process change point designed to detect changes in process variance of a normal quality characteristic when the change follows a linear trend. We describe how this estimator can be used to identify the change point when a Shewhart S-control chart signals a change in the process variance. Numerical results reveal that the proposed estimator outperforms the MLE designed for step change when a linear trend disturbance is present. تفاصيل المقالة -
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11 - Control Chart Recognition Patterns using Fuzzy Rule-Based System
Alireza Alinezhad Ali TaherinezhadControl Chart Patterns (CCPs) recognition is one the most important concepts in control chart application. Relating the patterns exhibited on the control chart to assignable causes is an ambiguous and vague task especially when multiple patterns co-exist. In this study, أکثرControl Chart Patterns (CCPs) recognition is one the most important concepts in control chart application. Relating the patterns exhibited on the control chart to assignable causes is an ambiguous and vague task especially when multiple patterns co-exist. In this study, a fuzzy rule-based system is developed for X ̅ control charts to prioritize the control chart causes based on the accumulated evidence. To demonstrate the reasonable performance of the proposed fuzzy rule-based system, the case studies are performed and the results are analyzed. تفاصيل المقالة -
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12 - Design of Control Charts for Monitoring Logistic Regression Profiles with Estimated Parameters
Zahra Musavipour Amirhossein Amiri Zahra JalilibalThe quality of a process can be described using a regression profile relationship between a response variable and some independent variables. Much research has been done on the response variables with continuous and normal distribution. While, in real situations, when a أکثرThe quality of a process can be described using a regression profile relationship between a response variable and some independent variables. Much research has been done on the response variables with continuous and normal distribution. While, in real situations, when a product is conforming or nonconforming on the product line, the assumption of normality is violated and a logistic regression model is used to characterize binary response variables. Also, in many cases the parameters used to design control charts for monitoring profiles are unknown and estimated by using IC reference data, which adversely influences the efficiency of control charts. In recent years, a few authors have been done on the effect of parameter estimation in monitoring profiles, especially profiles whose response variables do not follow the normal distribution. In this paper, Hotelling’s T2 chart and a multivariate exponentially weighted moving average (MEWMA) chart are used to monitor the logistic regression profile in Phase II with estimated parameters. In addition, two criteria including average of average run length (AARL) and standard deviation of average run length (SDARL) are utilized to appraise the effect of parameters estimation in Phase I on the Phase II performance of designed control charts through simulation runs. The results illustrate that the performance of these charts is significantly affected by the estimated parameters in both IC and OC conditions. Also, two methods are utilized to decrease the effect of parameters estimation which include increasing the number of reference profiles in Phase I and modifying the control limits. تفاصيل المقالة -
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13 - Multiple Dependent States Repetitive Sampling Control Chart for Monitoring Rayleigh Distributed Data
Srinivasa Rao Gadde Olatunde Adebayo AdeotiAn attribute control chart for Rayleigh distribution based on the multiple dependent state repetitive sampling (MDSRS) is developed in this paper. The performance of the proposed chart is evaluated in terms of average run length for the design of the proposed chart. Fur أکثرAn attribute control chart for Rayleigh distribution based on the multiple dependent state repetitive sampling (MDSRS) is developed in this paper. The performance of the proposed chart is evaluated in terms of average run length for the design of the proposed chart. Furthermore, the control chart constants for instance test time multiplier; inner and outer control limits coefficients are determined by considering the process in-control average run length (ARL) in support of different sample sizes. The efficiency of the proposed chart is compared with some competing control charts using other sampling methods such as single sampling (SS), multiple dependent states (MDS) and repetitive sampling (RS). The application of the proposed chart is illustrated using simulated data, which showed the superiority of the proposed chart as compared to the competing charts. Based on the ARL performance of the proposed chart and the application example, it is recommended that the process engineers use the proposed chart when monitoring the number of failed products that follow the Rayleigh distribution. تفاصيل المقالة -
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14 - Endpoint in plasma etch process using new modified w-multivariate charts and windowed regression
Sihem Ben Zakour Hassen TalebEndpoint detection is very important undertaking on the side of getting a good understanding and figuring out if a plasma etching process is done in the right way, especially if the etched area is very small (0.1%). It truly is a crucial part of supplying repeatable eff أکثرEndpoint detection is very important undertaking on the side of getting a good understanding and figuring out if a plasma etching process is done in the right way, especially if the etched area is very small (0.1%). It truly is a crucial part of supplying repeatable effects in every single wafer. When the film being etched has been completely cleared, the endpoint is reached. To ensure the desired device performance on the produced integrated circuit, the high optical emission spectroscopy (OES) sensor is employed. The huge number of gathered wavelengths (profiles) is then analyzed and pre-processed using a new proposed simple algorithm named Spectra peak selection (SPS) to select the important wavelengths, then we employ wavelet analysis (WA) to enhance the performance of detection by suppressing noise and redundant information. The selected and treated OES wavelengths are then used in modified multivariate control charts (MEWMA and Hotelling) for three statistics (mean, SD and CV) and windowed polynomial regression for mean. The employ of three aforementioned statistics is motivated by controlling mean shift, variance shift and their ratio (CV) if both mean and SD are not stable. The control charts show their performance in detecting endpoint especially W-mean Hotelling chart and the worst result is given by CV statistic. As the best detection of endpoint is given by the W-Hotelling mean statistic, this statistic will be used to construct a windowed wavelet Hotelling polynomial regression. This latter can only identify the window containing endpoint phenomenon. تفاصيل المقالة -
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15 - Economic design of x¯ control charts considering process shift distributions
Vijayababu Vommi Rukmini V. KasarapuProcess shift is an important input parameter in the economic design of control charts. Earlier x control chart designs considered constant shifts to occur in the mean of the process for a given assignable cause. This assumption has been criticized by many research أکثرProcess shift is an important input parameter in the economic design of control charts. Earlier x control chart designs considered constant shifts to occur in the mean of the process for a given assignable cause. This assumption has been criticized by many researchers since it may not be realistic to produce a constant shift whenever an assignable cause occurs. To overcome this difficulty, in the present work, a distribution for the shift parameter has been considered instead of a single value for a given assignable cause. Duncan’s economic design model for x chart has been extended to incorporate the distribution for the process shift parameter. It is proposed to minimize total expected loss-cost to obtain the control chart parameters. Further, three types of process shifts namely, positively skewed, uniform and negatively skewed distributions are considered and the situations where it is appropriate to use the suggested methodology are recommended. تفاصيل المقالة -
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16 - An ex ante control chart for project monitoring using earned duration management observations
Seyed Taha Hossein Mortaji Siamak Noori Rassoul Noorossana Morteza BagherpourIn the past few years, there has been an increasing interest in developing project control systems. The primary purpose of such systems is to indicate whether the actual performance is consistent with the baseline and to produce a signal in the case of non-compliance. R أکثرIn the past few years, there has been an increasing interest in developing project control systems. The primary purpose of such systems is to indicate whether the actual performance is consistent with the baseline and to produce a signal in the case of non-compliance. Recently, researchers have shown an increased interest in monitoring project’s performance indicators, by plotting them on the Shewhart-type control charts over time. However, these control charts are fundamentally designed for processes and ignore project-specific dynamics, which can lead to weak results and misleading interpretations. By paying close attention to the project baseline schedule and using statistical foundations, this paper proposes a new ex ante control chart which discriminates between acceptable (as-planned) and non-acceptable (not-as-planned) variations of the project’s schedule performance. Such control chart enables project managers to set more realistic thresholds leading to a better decision making for taking corrective and/or preventive actions. For the sake of clarity, an illustrative example has been presented to show how the ex ante control chart is constructed in practice. Furthermore, an experimental investigation has been set up to analyze the performance of the proposed control chart. As expected, the results confirm that, when a project starts to deflect significantly from the project’s baseline schedule, the ex ante control chart shows a respectable ability to detect and report right signals while avoiding false alarms. تفاصيل المقالة -
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17 - Economic design of Hotelling’s T2 control chart on the presence of fixed sampling rate and exponentially assignable causes
Ehsan Bahiraee Sadigh RaissiControl charts are extensively used in manufacturing contexts to monitor production processes. This article illustrates economical design of a variable sample size and control limit Hotelling’s T2 control chart based on a novel cost model when occurrence times أکثرControl charts are extensively used in manufacturing contexts to monitor production processes. This article illustrates economical design of a variable sample size and control limit Hotelling’s T2 control chart based on a novel cost model when occurrence times of the assignable causes are exponentially distributed. The proposed nonlinear cost model is an extension of Duncan’s (J Am Stat Assoc 51: 228–242, 1956) model which was employed for univariate cases. Applying genetic algorithm to find optimum parameter values and using an L33 orthogonal array in sensitivity analysis on the model parameters is investigated through a numerical example to illustrate the effectiveness of the proposed approach. تفاصيل المقالة -
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18 - On the use of multi-agent systems for the monitoring of industrial systems
Nafissa Rezki Okba Kazar Leila Hayet Mouss Laid Kahloul Djamil RezkiThe objective of the current paper is to present an intelligent system for complex process monitoring, based on artificial intelligence technologies. This system aims to realize with success all the complex process monitoring tasks that are: detection, diagnosis, identi أکثرThe objective of the current paper is to present an intelligent system for complex process monitoring, based on artificial intelligence technologies. This system aims to realize with success all the complex process monitoring tasks that are: detection, diagnosis, identification and reconfiguration. For this purpose, the development of a multi-agent system that combines multiple intelligences such as: multivariate control charts, neural networks, Bayesian networks and expert systems has became a necessity. The proposed system is evaluated in the monitoring of the complex process Tennessee Eastman process. تفاصيل المقالة -
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19 - Bayesian change point estimation in Poisson-based control charts
Hassan Assareh Rassoul Noorossana Kerrie L MengersenPrecise identification of the time when a process has changed enables process engineers to search for a potential special cause more effectively. In this paper, we develop change point estimation methods for a Poisson process in a Bayesian framework. We apply Bayesian أکثرPrecise identification of the time when a process has changed enables process engineers to search for a potential special cause more effectively. In this paper, we develop change point estimation methods for a Poisson process in a Bayesian framework. We apply Bayesian hierarchical models to formulate the change point where there exists a step change, a linear trend and a known multiple number of changes in the Poisson rate. The Markov chain Monte Carlo is used to obtain posterior distributions of the change point parameters and corresponding probabilistic intervals and inferences. The performance of the Bayesian estimator is investigated through simulations and the result shows that precise estimates can be obtained when they are used in conjunction with the well-known c-, Poisson exponentially weighted moving average (EWMA) and Poisson cumulative sum (CUSUM) control charts for different change type scenarios. We also apply the Deviance Information Criterion as a model selection criterion in the Bayesian context, to find the best change point model for a given dataset where there is no prior knowledge about the change type in the process. In comparison with built-in estimators of EWMA and CUSUM charts and ML based estimators, the Bayesian estimator performs reasonably well and remains a strong alternative. These superiorities are enhanced when probability quantification, flexibility and generalizability of the Bayesian change point detection model are also considered. تفاصيل المقالة -
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20 - Process capability improvement through DMAIC for aluminum alloy wheel machining
G. V. S . S. Sharma P. Srinivasa Rao B. Surendra BabuThis paper first enlists the generic problems of alloy wheel machining and subsequently details on the process improvement of the identified critical-to-quality machining characteristic of A356 aluminum alloy wheel machining process. The causal factors are traced using أکثرThis paper first enlists the generic problems of alloy wheel machining and subsequently details on the process improvement of the identified critical-to-quality machining characteristic of A356 aluminum alloy wheel machining process. The causal factors are traced using the Ishikawa diagram and prioritization of corrective actions is done through process failure modes and effects analysis. Process monitoring charts are employed for improving the process capability index of the process, at the industrial benchmark of four sigma level, which is equal to the value of 1.33. The procedure adopted for improving the process capability levels is the define-measure-analyze-improve-control (DMAIC) approach. By following the DMAIC approach, theCp,CpkandCpmshowed signs of improvement from an initial value of 0.66, −0.24 and 0.27, to a final value of 4.19, 3.24 and 1.41, respectively. تفاصيل المقالة -
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21 - Control chart based on residues: Is a good methodology to detect outliers?
Jean Paulo Guarnieri Adriano Mendonça Souza Luciane Flores Jacobi Bianca Reichert Claudimar Pereira da VeigaThe purpose of this article is to evaluate the application of forecasting models along with the use of residual control charts to assess production processes whose samples have autocorrelation characteristics. The main objective is to determine the efficiency of control أکثرThe purpose of this article is to evaluate the application of forecasting models along with the use of residual control charts to assess production processes whose samples have autocorrelation characteristics. The main objective is to determine the efficiency of control charts for individual observations (CCIO) and exponentially weighted moving average (EWMA) charts when they are applied to residuals of models of AR(1) or MA(1) to detect outlier in autocorrelated processes. Considering autocorrelation strength and sign in the data series and the outlier range, the series were simulated accomplishing 640,000 sets. The series were contaminated by anomalous observations at 100th position, an AR(1) or MA(1) model were fitted, and the residuals were evaluated by CCIO and EWMA control charts; the points correctly detected as an autocorrelation were recorded. For the parameters investigated (autocorrelation and outlier range), a detection rate was generated in each chart, and nonparametric comparison tests were applied. The result of the tests showed the superiority (p < /em> < 0.05) of the CCIO chart for both models. The study of the influence of the sign and magnitude of the autocorrelation parameter showed no significant (p < /em> > 0.05) for either AR(1) or MA(1) charts and models. In this context, control charts for individual observations (CCIO) were confirmed to effectively detect outliers through residuals in industrial autocorrelated processes originated in first-order AR and MA models. تفاصيل المقالة -
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22 - A new approach Spider's web initial solution and data envelopment analysis for solving an $X$-bar control chart
K. Ranjbar H. Khaloozadeh A. Heydari$X$-bar control charts are widely used to monitor and control business and manufacturing processes. Design of control charts refers to the selection of parameters, including sample size, control-limit width, and sampling frequency. Many researchers have worked on this i أکثر$X$-bar control charts are widely used to monitor and control business and manufacturing processes. Design of control charts refers to the selection of parameters, including sample size, control-limit width, and sampling frequency. Many researchers have worked on this issue and have also proposed various solutions. However, despite the numerous advantages, the proposed methods also have their own set of problems. The biggest challenge is the complexity of solving these issues. Due to the fact that optimal design of control charts can be formulated as a multi objective optimization problem, in this paper to solve this problem, we used initial solution Spider's web data envelopment analysis method. In previous methods used multiple algorithms to resolve the issue. But in the proposed method once using Data Envelopment Analysis method and without any other algorithm can solve multi objective problem and this method can yield desirable efficient. Lastly, we compare our method with others and demonstrate its application in a real industrial context. تفاصيل المقالة
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