摘要:

The usual practice in using a control chart to monitor a process is to take samples of sizenfrom the process everyhhours. This article considers the properties of theX̄chart when the size of each sample depends on what is observed in the preceding sample. The idea is that the sample should be large if the sample point of the preceding sample is close to but not actually outside the control limits and small if the sample point is close to the target. The properties of the variable sample size (VSS)X̄chart are obtained using Markov chains. The VSSX̄chart is substantially quicker than the traditionalX̄chart in detecting moderate shifts in the process.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979523

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

A conventionalX̄control chart works in an open loop manner. That is, the process control engineer waits until the control scheme signals an out-of-control condition. This paper proposes a combined adaptiveX̄chart that uses real-time, dynamic information available from the process to make the control scheme proactive. The procedure consists of a simple method of varying the control chart design parameters (sample size and sampling interval) between minimum and maximum values depending on the current state of the process. The proposed procedure is compared with the standard ShewhartX̄chart, a variable sample size chart, and a variable sampling interval chart in terms of the average time to signal an off-target process. Substantial improvement in the performance over these schemes is demonstrated. Optimal values for the maximum sample size are also given. The advantages of using the combined adaptive chart is illustrated by an example from a production process.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979524

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

A mixture experiment involves varying the proportions of two or more ingredients, called components of the mixture, and studying the changes that occur in the measured properties (responses) of the resulting end products. Other factors that affect the response(s) such as process variables or the total amount of the mixture may also be studied in the experiment. Five approaches for designing mixture experiments and analyzing the data are considered: component proportion, mixture-amount, mixture-process variable, mathematically independent variables, and slack variable. The approaches are illustrated using examples from the literature. The various approaches are discussed and recommendations are made for choosing among the approaches when faced with a mixture experiment problem. A five-component waste grout example for which several mixture experiment approaches are possible is discussed.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979525

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Many quality control problems are multivariate in character since the quality of a given product or object consists simultaneously of more than one variable. A good multivariate quality control procedure should possess three important properties, namely, the control of the overall error rate, the easy identification of errant variables, and the easy quantification of any changes in the variable means. In this paper a procedure is suggested based on the construction of exact simultaneous confidence intervals for each of the variable means that meets each of these three goals. Both parametric and nonparametric procedures are considered, and critical point evaluation through tables, numerical integration, and simulation is discussed. Various examples of the implementation of the procedure are given.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979526

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

It has been well accepted that dependence on inspection to correct quality problems is ineffective and costly, and hence screening (100% inspection) should not be used as a long-term solution for improving product quality. However, screening may be an attractive practice for removing nonconforming items from a population in the short term because of the advances in automatic inspection equipment and computer control in manufacturing. Important factors considered in designing screening procedures include the selection of screening variable, available information on the population being studied, cost of inspection, losses caused by decision errors, the variation in product quality, and inspection and manufacturing environments. This paper presents a systematic review of the literature on the design of screening procedures.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979527

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

A FORTRAN program that enables users to determine economic, statistical, or economic-statisticalX̄chart designs is presented. Economic designs are designs that minimize cost as measured by the Lorenzen-Vance cost function. Statistical designs are designs that satisfy a series of average run length constraints associated with various degrees of shift in the process mean. These two concepts are combined to find economic-statistical designs, where cost is minimized subject to average run length constraints.

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979528

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979529

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979530

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979532

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

ISSN:0022-4065    

DOI:10.1080/00224065.1994.11979533

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor