VPLS Based Quality and Cost Control for Tennessee Eastman Process

Product quality and operation cost control obtain increasing emphases in modern chemical system engineering. To improve the fault detection power of the partial least square (PLS) method for quality control, a new QRPV statistic is proposed in terms of the VP (variable importance in projection) indices of monitored process variables, which is significantly advanced over and different from the conventional Q statistic. QRPV is calculated only by the residuals of the remarkable process variables (RPVs). Therefore, it is the dominant relation between quality and RPV not all process variables (as in the case of the conventional PLS) that is monitored by this new VP-PLS (VPLS) method. The combination of QRPV and T2 statistics is applied to the quality and cost control of the Tennessee Eastman (TE) process, and weak faults can be detected as quickly as possible. Consequently, the product quality of TE process is guaranteed and operation costs are reduced.

Study on Quality and Safety Trust Early Warning of Dairy Products Based on Statistical Process Control

In order to solve such problems as lack of dynamic evaluation system in evaluation of quality and safety trust of dairy products,and weak awareness of prevention,it is necessary to introduce the statistical process control into the quality and safety trust evaluation system of dairy products,and establish quality and safety trust early warning model for dairy products,so as to determine the control limit of control chart and carry out early warning according to eight criteria. According to the empirical results,the statistical process control is helpful for finding the hidden process risks and providing the necessary basis for enterprises taking positive measures to raise the confidence of consumers.

Application of Statistical Process Control for Setting Action Thresholds as Quality Assurance of Dose Verifications in External Beam Radiotherapy

Purpose: To test the concept of Statistical Process Control (SPC) as a Quality Assurance (QA) procedure for dose verifications in external beam radiation therapy in conventional and 3D Conformal Radiotherapy (3D-CRT) treatment of cervical cancer. Materials and Methods: A study of QA verification of target doses of 198 cervical cancer patients undergoing External Beam Radiotherapy (EBRT) treatments at two different cancer treatment centers in Kenya was conducted. The target doses were determined from measured entrance doses by the diode in vivo dosimetry. Process Behavior Charts (PBC) developed by SPC were applied for setting Action Thresholds (AT) on the target doses. The AT set was then proposed as QA limits for acceptance or rejection of verified target doses overtime of the EBRT process. Result and Discussion: Target doses for the 198 patients were calculated and SPC applied to test whether the action limits set by the Process Behavior Charts could be applied as QA for verified doses in EBRT. Results for the two sub-groups of n = 3 and n = 4 that were tested produced action thresholds which are within clinical dose specifications for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. Conclusion: Action thresholds set by SPC were within the clinical dose specification of ±5% uncertainty for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. So the concept of SPC could be applied in setting QA action limits for dose verifications in EBRT.

Assessing the Awareness and Usage of Quality Control Tools with Emphasis to Statistical Process Control (SPC) in Ethiopian Manufacturing Industries

Introduction: The present work was devoted to assess the awareness and usage of quality control tools with the emphasis on statistical process control in Ethiopian manufacturing industries. Semi structured questionnaire has been employed to executive and technical managers of manufacturing industries of various size and specialism across the country. Stratified random sample method by region was used to select sample industries for the study. The samples used for this study are industries mainly from Oromiya, Addis Ababa, Tigray, Amara, SNNP and Diredawa regions proportional to their size of the available industries. Methods: Exploratory method and descriptive statistics was used for data analysis. Available documents and reports related to quality control policy of the selected companies were investigated. Results and Discussions: The number of manufacturing industries involved in this study was 44. Of the sampled manufacturing industries about 60% are from Oromiya and Addis Ababa regions. It has been reported that 100% of the respondents said that the importance of quality control tools is very important to their organizations’ productivity and quality improvement (Figure 3). Quality control professionals were also asked the extent to which quality control system is working in their industry and majority of the respondents (45%) have indicated that quality control system is working to some extent in their respective industries (Figure 18). Conclusions and Recommendations: Most of the quality department of the industries did not fully recognize the importance of statistical process control as quality control tools. This is mainly due to lack of awareness and motivation of the top managements, shortage of man power in the area, and others together would make it difficult to apply quality control tools in their organization. In general, the industries in Ethiopia are deficient in vigor and found to be stagnant hence less exposed to a highly competitive market and don’t adopt the latest quality control techniques in order to gain knowledge about systems to improve quality and operational performance. We conclude that quality management system has to be established as an independent entity with a real power and hence the quality control department which is responsible for quality can make an irreversible decision with respect to quality of any given product. Moreover, the concerned bodies (government and ministry of industries) should give attention and work together with universities to ensure how these statistical process control techniques could be incorporated in a curriculum of the universities at higher levels in degree and masters programs. Furthermore, different trainings which could improve quality and efficiency of their respective management system should be given as short and long term to the employees including top and middle managers found in various industries relevant to their process.

Multivariate Statistical Process Monitoring and Control: Recent Developments and Applications to Chemical Industry

Multivariate statistical process monitoring and control (MSPM&C) methods for chemical process monitoring with statistical projection techniques such as principal component analysis (PCA) and partial least squares (PLS) are surveyed in this paper. The four-step procedure of performing MSPM&C for chemical process, modeling of processes, detecting abnormal events or faults, identifying the variable(s) responsible for the faults and diagnosing the source cause for the abnormal behavior, is analyzed. Several main research directions of MSPM&C reported in the literature are discussed, such as multi-way principal component analysis (MPCA) for batch process, statistical monitoring and control for nonlinear process, dynamic PCA and dynamic PLS, and on-line quality control by inferential models. Industrial applications of MSPM&C to several typical chemical processes, such as chemical reactor, distillation column, polymerization process, petroleum refinery units, are summarized. Finally, some concluding remarks and future considerations are made.

A Study of Detection of Outliers for Working and Non-Working Days Air Quality in Kolkata, India: A Case Study

A variety of factors affect air quality, making it a difficult issue. The level of clean air in a certain area is referred to as air quality. It is challenging for conventional approaches to correctly discover aberrant values or outliers due to the significant fluctuation of this sort of data, which is influenced by Climate change and the environment. With accelerating industrial expansion and rising population density in Kolkata City, air pollution is continuously rising. This study involves two phases, in the first phase imputation of missing values and second detection of outliers using Statistical Process Control (SPC), and Functional Data Analysis (FDA), studies to achieve the efficacy of the outlier identification methodology proposed with working days and Nonworking days of the variables NO2, SO2, and O3, which were used for a year in a row in Kolkata, India. The results show how the functional data approach outshines traditional outlier detection methods. The outcomes show that functional data analysis vibrates more than the other two approaches after imputation, and the suggested outlier detector is absolutely appropriate for the precise detection of outliers in highly variable data.

基于二项分布的统计过程控制方法在血液质量控制中的应用研究

目的通过引入统计过程控制(SPC)方法,分析去白细胞悬浮红细胞的质量控制项目,以期在血液质量控制数据的有效应用方面取得进展,并为血液质量的持续改进提供循证依据。方法自2020—2022年,收集了重庆地区6家血站的去白细胞悬浮红细胞质量控制项目检测数据。利用Minitab软件进行统计过程控制分析,绘制p控制图,计算各质控项目的不符合率及其95%置信区间,以及过程能力指数(Z值)。结果根据《全血及成分血质量要求》对去白细胞悬浮红细胞的质量控制项目进行评估,得出外观、储存期末溶血率、无菌试验符合率均为100%。然而,容量、血红蛋白含量、血细胞比容、白细胞残留量的符合率未能达到100%,但均≥75%。通过基于二项分布的p控制图,进一步识别了生产过程的受控状态。在总体符合率满足国标要求的情况下,发现容量、血红蛋白含量、血细胞比容、白细胞残留量在不同机构中存在失控点,并呈现出明显的趋势。各质控项目的不符合率虽均小于25%,但在95%置信水平下,B、C、E、F,4家血站的白细胞残留量显示不符合规定(>25%)。通过构建能力评价指标Z值进行计数资料的过程能力分析,结果显示E机构的容量,以及B、C、F机构的血细胞比容和全部6家血站的白细胞残留量Z值均<2,提示存在质量改进的空间。结论基于二项分布的统计过程控制方法,对血液成分质量控制具有较好的应用价值,能够进一步实现对血液采集、制备和储存过程的实时监控和过程改进。

多变量统计过程控制技术在药品生产过程中的应用

介绍了多变量统计过程控制(multivariate statistical process control,MSPC)的基本概念和有关背景。描述了MSPC实施的基本流程以及常用统计量与控制图。强调了MSPC在药品生产过程中的重要作用,特别是中药领域,为药品生产过程质量控制方法的选择提供参考。总结了MSPC的优势和不足,并展望了MSPC在药品生产和质量控制方面的发展趋势。

基于SPC的电机生产过程质量监督

为解决电机生产过程质量监督问题,提出一种基于统计过程控制(SPC)图的电机生产过程质量监督方法,分析了具体流程和步骤,实例结果表明,该方法是有效、可行的。

二段炉内衬更换施工控制要点简述

从二段炉内衬更换施工作业准备、作业程序、作业方法、作业内容、作业技术要点、质量控制要点等方面,论述了内衬更换施工过程及重点部位的控制要点。

基于危害分析与关键控制点和流程再造理论的大型医院静脉采血流程优化与对策研究

本文采用危害分析与关键控制点质量控制体系和流程再造理论,分析首都医科大学附属北京天坛医院静脉采血流程各环节的关键控制点及潜在危害因素,提出优化措施。通过构建智慧采血预约平台等措施,优化采血流程,减少等待时间,优化诊疗环境,降低成本,取得了良好的社会效益和经济效益。

统计过程控制方法在放疗患者计划质控中的应用

目的运用统计过程控制(SPC)方法建立基于电子射野影像设备(Electronic Portal Imaging Device,EPID)在不同部位、不同放疗技术下使用3%/2mm和3%/3mm基准进行伽马分析的容差限值与干预限值。方法分别选取头颈部、胸部、腹部及其他部位的129例IMRT计划和89例VMAT计划使用EPID进行剂量验证,根据每个部位前20例患者计划的伽马通过率结果计算对应的容差限值与干预限值,绘制相应的单值控制图,实时监测各部位所有计划在不同测量基准下的伽马通过率。结果两种放疗技术在3%/3mm基准下,各部位的容差下限均大于97%,干预下限均接近于97%。3%/2mm基准下,各部位的容差下限均大于94%,干预下限均大于92%。结论SPC方法能够实时、有效的监测改进放疗患者计划质控流程,制定不同部位、不同放疗技术在不同测量基准下的个体化容差干预限值,降低失误风险,减少临床事故的发生。

汽车制造过程中的螺纹连接质量监控及预警

螺纹连接装配质量对汽车整车制造有着极其重要的作用。介绍了统计过程控制(statistical process control,SPC)在本公司总装车间螺纹连接残余扭矩质量检测过程中的应用,并结合实际案例,分享了过程能力指数(Cpk)对生产系统稳定性预警专项提升项目。

浮法玻璃硅质原料质量控制

硅质原料质量控制是浮法玻璃生产的一项重要工作,原矿品位、加工工艺决定硅质原料的加工质量,均化良好和水分补偿是硅质原料使用的关键环节。通过具体论述影响硅质原料的外观、水分、理化指标、粒度和COD值等相关因素,提出硅质原料的相关指标控制要求,并对普通浮法玻璃和超白浮法玻璃的控制要求进行对比,通过综合控制和管理来获得适合浮法玻璃生产要求的硅质原料。

A strategy for population pharmaceutical quality assessment based on quality by design

From a regulatory perspective,drug quality consistency evaluation must concern different processes used for the same drug.In this study,an assessment strategy based on quality by design(QbD)was developed for population pharmaceutical quality evaluation.A descriptive analysis method based on QbD concept was first established to characterize the process by critical evaluation attributes(CEAs).Then quantitative analysis method based on an improved statistical process control(SPC)method was established to investigate the process indicators(PIs)in the process population,such as mean distribution,batch-to-batch difference and abnormal quality probability.After that rules for risk assessment were established based on the SPC limitations and parameters.Both the SPC parameters of the CEAs and the risk of PIs were visualized according to the interaction test results to obtain a better understanding of the population pharmaceutical quality.Finally,an assessment strategy was built and applied to generic drug consistency assessment,process risk assessment and quality trend tracking.The strategy demonstrated in this study could help reveal quality consistency from the perspective of process control and process risk,and further show the recent development status of domestic pharmaceutical production processes.In addition,a process risk assessment and population quality trend tracking provide databased information for approval.Not only can this information serve as a further basis for decisionmaking by the regulatory authority regarding early warnings,but it can also reduce some avoidable adverse reactions.With continuous addition of data,dynamic population pharmaceutical quality is meaningful for emergencies and decision-making regarding drug regulation.

Combining the People Power and the Process Power to Achieve Six Sigma Process Capability——A Case Study

Achieving Six-Sigma process capability starts with l istening to the Voice of the Customers, and it becomes a reality by combining th e People Power and the Process Power of the organisation. This paper presents a Six-Sigma implementation case study carried out in a magnet manufacturing compa ny, which produces bearing magnets to be used in energy meters. If the thickness of the produced bearing magnets is between 2.35 mm and 2.50 mm, they will be ac cepted by the customers. All the time the company could not produce the bearing magnets within the specified thickness range, as their process distribution was flat with 2.20 mm as lower control limit and 2.60 mm as upper control limit. This resulted in a huge loss in the form of non-conformities, loss of time and goodwill. The process capability of the company then was around 0.40. Organisat ion restructuring was carried out to reap the benefit of the People Power of the organisation. Statistically designed experiments (Taguchi Method based Design o f Experiments), Online quality control tools (Statistical Process Control To ols) were effectively used to complete the DMAIC (Define, Measure, Analyse, Impr ove and Control) cycle to reap the benefit of the Process Power of the organisat ion. Presently the company enjoys a process capability of 1.75, a way towards Si x-Sigma Process Capability.

Engineering Quality and Knowledge Systems： An Appraisal for Improving the Spinning Stage

The industrial organisations have a vested interest in quality and its practices in making a quantum leap, thereby requiring proper refocusing and rethinking. This is targeted seriously towards firms acquiring Knowledge Systems （KS） in order to nurture the employees＇ capabilities. Therefore, to enhance performances and their highly creative direction takes consideration of QE （quality engineering） and KS and disciplines complementary to each other. Additionally, the flow of operations and activities of the KS through the application of quality engineering （QE） principles is according to the view of Japanese engineer Taguchi. This aims to achieve good quality in the product design and processes, and also to anticipate problems that may occur before the shipping of the products. In this study, the use of quality control engineering and Taguchi＇s function methods in determining these properties and the loss caused by the company will be examined. However, the adopted approach of study scope to the society will aid KS. Also, efforts in this direction motivate the employment of a statistical method by Taguchi which relied on the principle of target-oriented quality, representing the value characterising the product quality.

血液成分质量抽检统计过程控制方法的探讨

目的 探讨血站在血液成分质量抽检过程中,检测数据的分析方法。方法 收集2018—2022年本中心的血液成分质量抽检检测数据,利用统计过程控制原理,使用Mintab软件绘制控制图,对部分关键检测项目数据进行统计过程控制分析。结果 对血小板含量项目的合格率采用P控制图分析,检验出1个失控点。对血浆蛋白含量项目进行正态性检验,分析数据波动原因,寻找改进方向。对于血细胞比容项目,绘制均值极差控制图,检验出数据异常趋势,对数据做正态性检验出并进行过程能力分析,Cpk值为0.67。结论 运用统计过程控制方法,用P控制图分析血液成分质量抽检中的计数型数据,对计量型数据进行正态性检验,并利用均值极差控制图检验数据的异常趋势,对符合正态性分布的数据,计算其过程能力指数Cpk值,不失为监测采供血过程稳定性的有效方法。

统计过程控制在医用电子直线加速器机械性能监测中的应用

目的:使用统计过程控制方法分析医用电子直线加速器长期过程表现,监测加速器状态变化趋势,并评估加速器各项指标性能状态。方法:收集2019年6月至2021年4月加速器机器性能检测(MPC)数据。绘制每个机械指标的单值控制图,分析各指标过程特征,并使用过程能力指数C_(pk)及C_(p)评估加速器各项机械指标的过程质量。结果:加速器机械精度明显优于当前厂商推荐的规格限值,但控制图监测结果显示各指标均存在一定程度的过程漂移。过程能力分析结果显示所有指标的C_(pk)及C_(p)均大于1.33,过程质量优秀。结论:加速器在满足当前MPC规格限的情况下依然可能发生过程失控。统计过程控制方法可及时发现过程中的异常改变,过程能力指数可有效评估过程质量,为质量管理及临床决策提供有效的信息。

通用型指数加权移动平均控制图的设计

为提高质量控制图监测微小到中等过程偏移的灵敏度,文章提出一种新的用于过程均值监控的通用型指数加权移动平均(UEWMA)控制图,该控制图是EWMA控制图的一般性推广,根据数据特征,自定义选取平滑系数λ_(1),λ_(2),…,λ_(s),使控制效果达到最优;给出UEWMA控制图的均值与控制限的求取方法,并推导出平均运行长度(ARL)和运行长度标准偏差(SDRL);最后,研究平滑系数对该控制图性能的影响,并将其与现有控制图监测微小到中等过程偏移的灵敏度进行比较。研究结果表明,UEWMA控制图通过数据特征设计平滑系数,具有灵活性好、灵敏度高、扩展性强和控制效果好的特点。