CUSUM控制图的一种优化设计方法研究

提出了一种以田口质量损失函数最小为目标的CUSUM控制图优化设计方法，建立了优化设计理论模型，提出了优化分析的流程，进行了实例分析和验证。     

CUSUM控制图在空调充氟生产过程中的应用研究

经典的休哈特控制对质量特征值的均值波动检出力较强,采用单值－移动极差控制图控制空调充氟量在短期内往往很难发现充氟量偏差值的漂移,导致充氟量偏差调整不及时,本文采用累积和控制图（CUSUM）来控制充氟量偏差的变化,改进了充氟偏差调整方式,中保证质量的同时降低了生产成本。     

基于CUSUM控制图和SVM的单病种成本差异分析

CUSUM控制图可用来监测均值的偏移.在单病种成本值发生重大差异前,短期内会发生一定失控趋势,CUSUM控制图却不能及时发出失控信号.针对成本差异分析中存在的问题,提出了基于支持向量机(SVM)的智能化单病种成本差异分析模型来替代CUSUM控制图.首先利用支持向量机(SVM)自身良好的泛化能力经过训练后获得复杂成本值之间的内在规律,然后对测试样本进行有效的预测分类,及时给出失控的样本点.将模型应用到单纯性阑尾炎病人样本中,与CUSUM控制图方法作比较,结果显示了该模型比CUSUM控制图更加及时发现有失控趋势或失控的样本点.     

基于田口质量损失函数思想的均值控制图的经济设计

田口质量损失函数中的质量损失不仅仅存在于不合格品中,同样也存在于合格品中.为了减少合格品的质量损失费用,提高产品质量,增加企业效益,本文利用田口质量损失函数,以使系统发出警报前的产品的期望质量损失费用最小为目标,建立了带警戒限均值控制图的优化数学模型,并且通过一个实例给出了利用LINGO程序求设计参数的方法.     

作业成本法的经济生产批量模型

应用作业成本法(ABC)于传统的经济生产批量问题.这一模型不仅考虑了库存补货成本、库存持有成本和缺货成本,同时还考虑了生产批量和生产周期成本.通过Lingo进行数值计算,结果显示新模型优于传统的模型.     

累积冲击下的经济生产批量及视情维修联合优化问题

为解决传统基于设备不会失效假设下经济生产批量问题研究的不足,考虑经济生产批量系统中设备失效维修的问题,提出了生产批量和视情维修联合优化的方法。基于泊松过程和一般分布构建冲击到达过程及累积冲击效应,结合设备退化观测和具体的维护费用结构,给出了可修退化系统最优的生产批量和视情维修阈值的求解模型。通过数值分析验证了最优策略的有效性,并进行了参数的敏感性分析,为设备管理者提供决策依据。     

经济批量原理在实际生产中的应用

在多品种小批量的生产组织中,合适的生产批量对于提高生产效率有着极其重要的意义,而灵活地运用经济批量法原理,选择恰当的求值约束条件,则是制定适合企业自身特点生产批量的关键。     

联合监控均值和方差的累积和控制图优化设计

为了提高监测均值和方差微小偏移的敏感度,围绕生产过程质量控制,建立同时监控均值和方差的累积和控制图.模型考虑均值和方差的变化,针对生产过程中的微小偏差,提出了一个新的累积和控制图,并给出了基于马尔可夫链理论的新控制图的平均链长计算方法.编程求解后对比文献中各控制图的平均链长数据以及更换变量数值改进控制图,通过计算变动比率得出新控制图的检测力度在不同偏移力度下都明显优于其他控制图方法.     

基于田口质量损失函数的控制图优化设计

由于在生产实际中存在大量非正态过程,传统控制图将失去其有效性.针对实际生产过程中质量特性不服从正态分布的情况,以Burr分布作为非正态数据的近似分布,结合均值随机漂移和田口质量损失函数,给出(X)图的经济统计最优设计方法;根据过程输出数据,提出最优样本容量及控制限的选择.数值计算的结果显示该方法可靠;通过灵敏度分析,研究了各参数对最优设计的影响.     

与控制点方法论相结合的V-mask累积和控制图

V-mask累积和控制图虽然能够有效地监控过程中发生的微小偏移,但是因为它需要存储大量统计量且计算时间较长,所以在计算机中实施起来比较困难.为了解决这一问题,介绍了将控制点方法论应用于V-mask累积和控制图这一方法,并通过实例来进一步说明.结果表明,与控制点方法论结合的控制图减少了存储量,缩短了计算时间,而且将在顾客满意度控制中得到广泛应用.     

The Economic Design of ―x Charts: A Proactive Approach

It has long been recognized that poor quality can only result in higher costs. Yet, the idea of reducing cost through better quality is not fully realized. Current models for the economic design of control charts provide strategies to maintain existing quality levels. In this research, a comprehensive cost model is developed to incorporate two cost functions. A reactive function, which accounts for all quality related costs incurred while maintaining a stable level of the process, and a proactive function, which accounts for the cost of process improvement. Using incremental economics, the two cost functions are assembled to allow an evaluation of process improvement alternatives based on their economic worth. Procedures for obtaining economically optimum designs for controlling the process mean are developed and designed experiments are utilized to investigate model performance over a wide range of input parameters. The results indicate that the model is sensitive to changes in 13 parameters, especially when the magnitude of the process shift is small. Copyright © 2004 John Wiley & Sons, Ltd.     

Design of EWMA and CUSUM control charts subject to random shift sizes and quality impacts

Statistical process control charts are important tools for detecting process shifts. To ensure accurate, responsive fault detection, control chart design is critical. In the literature, control charts are typically designed by minimizing the control chart's responding time, i.e., average run length (ARL), to an anticipated shift size under a tolerable false alarm rate. However, process shifts, originating from various variation sources, often come with different sizes and result in different degrees of quality impacts. In this paper, we propose a new performance measure for EWMA and CUSUM control chart design to take into consideration the variable shift sizes and corresponding quality impacts. Unlike economic designs of control charts that suffer from a complex cost structure and intensive numerical computation, the proposed design methodology does not involve any cost estimation and the design procedure is as simple as looking up tables. Given the Gaussian random shifts and quadratic quality loss function, we show that the proposed design has a significant reduction in the quality impact as compared to conventional ARL-based designs. Guidelines and useful worksheets for practical implementation of the proposed designs are then suggested to practitioners with different knowledge levels of the process excursions.     

Computing the Percentage Points of the Run-Length Distributions of Multivariate CUSUM Control Charts

Multivariate CUSUM control charts are often used instead of the standard Hotelling's control charts in many practical problems when detection of small shifts in the process mean is important. However, design of multivariate CUSUM control charts are usually based on the average run length (ARL). In this work, we will compute the percentage points of the run-length distributions of two multivariate CUSUM control charts. It will be shown that interpretations based on ARL can be misleading since the in-control run-length distribution of a multivariate CUSUM is highly skewed. On the other hand, the percentage points of the run-length distribution provide additional information such as the median run length, early false out-of-control signals, and the skewness of the run-length distribution for a particular scheme. These extra information might provide quality control engineers further knowledge of a particular multivariate CUSUM control chart scheme.     

New Synthetic EWMA and Synthetic CUSUM Control Charts for Monitoring the Process Mean

Exponentially weighted moving average (EWMA) and cumulative sum (CUSUM) control charts are potentially powerful statistical process monitoring tools because of their excellent speed in detecting small to moderate persistent process shifts. Recently, synthetic EWMA (SynEWMA) and synthetic CUSUM (SynCUSUM) control charts have been proposed based on simple random sampling (SRS) by integrating the EWMA and CUSUM control charts with the conforming run length control chart, respectively. These synthetic control charts provide overall superior detection over a range of mean shift sizes. In this article, we propose new SynEWMA and SynCUSUM control charts based on ranked set sampling (RSS) and median RSS (MRSS) schemes, named SynEWMA‐RSS and SynEWMA‐MRSS charts, respectively, for monitoring the process mean. Extensive Monte Carlo simulations are used to estimate the run length characteristics of the proposed control charts. The run length performances of these control charts are compared with their existing powerful counterparts based on SRS, RSS and MRSS schemes. It turns out that the proposed charts perform uniformly better than the Shewhart, optimal synthetic, optimal EWMA, optimal CUSUM, near‐optimal SynEWMA, near‐optimal SynCUSUM control charts based on SRS, and combined Shewhart‐EWMA control charts based on RSS and MRSS schemes. A similar trend is observed when constructing the proposed control charts based on imperfect RSS schemes. An application to a real data is also provided to demonstrate the implementations of the proposed SynEWMA and SynCUSUM control charts. Copyright © 2014 John Wiley & Sons, Ltd.     

Control Charts monitoring Product's Loss to Society

Taguchi introduced a new philosophy in quality control that accounts for the economic loss associated to process variation measured by deviations from the target value of a product quality characteristic. The Taguchi loss function has been considered in the design of control charts only for the computation of costs associated with nonconformities. This paper considers sample statistics based on the Taguchi loss function as a means to implement Shewhart control charts monitoring both the deviation from the target and dispersion of normally distributed quality characteristics. The aim of this proposed control chart is to perform on‐line quality control of a process by monitoring its quality loss cost performance over time. To compute the quality loss performance, we consider a nominal‐the‐best quality characteristic. The statistical performance of the proposed control charts has been evaluated and compared with that of widely used control charts. Implementing target costing philosophy by means of one of the proposed charts is also discussed. An example illustrates the Taguchi control chart in a practical implementation. Copyright © 2013 John Wiley & Sons, Ltd.