摘要:

AbstractIn processes where the length of the production run is short, data to estimate the process parameters and control limits may not be available prior to the start of production, and because of the short run time, traditional methods for establishing control charts cannot be easily applied. Recently,Qcharts have been proposed to address this problem. We study the average run length (ARL) ofQcharts for a normally distributed variable assuming that a sustained shift occurs in the quality characteristic. It is shown that in some casesQcharts do not exhibit adequate ARL performance. Modifications that enhance the ARL properties ofQcharts are presented. Some alternatives toQcharts are also discussed. For the case of a known process target two alternative methods are presented: an exponentially weighted moving average (EWMA) method and an adaptive Kalman filtering method. It is shown that both methods have better ARL performance thanQcharts for that case. For the case of both process parameters unknown, an adaptive Kalman filtering method used with a tracking signal provides an ARL performance that improves as better estimates of the process mean and variance are given. A practical example illustrates the tracking signal method for the case when the process parameters are unknown.

ISSN:0748-8017    

DOI:10.1002/qre.4680100203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe paper examines two very important non‐parametric estimators of the reliability function which are frequently used in reliability practice to estimate survival probabilities. The paper proves that when both of them are calculated for the same data set, the survival probabilities obtained using the cumulative hazard approach are larger in magnitude than the ones given by the method proposed by Kaplan and Meier, and provides the mathematical formula quantifying the magnitude of this differenc

ISSN:0748-8017    

DOI:10.1002/qre.4680100204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper provides tabulated numerical values for the gamma function necessary for the analytical estimation of the mean and standard deviation of the Weibull distribution. The tables produced also include estimates of the Weibull coefficient of variation, a quantity very important for maintenance optimization calculations when Glasser's charts are employed.

ISSN:0748-8017    

DOI:10.1002/qre.4680100205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractTaguchi1has provided 18 orthogonal arrays which have been widely touted as useful frameworks for planning experiments. Thirteen of these are ‘saturated designs’, that is, they are appropriate for investigating (N‐ 1) factors inNruns, thus using the full capacity of the design. Here, the other five ‘non‐saturated’ designs are discussed. By creating additional, orthogonal columns which provide estimates of interaction effects, we can essentially wring out some additional information over and above that suggested by Taguchi, without additional cost. In particular, if only the linear effect is of interest for any specific factor, one can accommodate more factors than the number suggested by Taguchi. An example is given for i

ISSN:0748-8017    

DOI:10.1002/qre.4680100206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe technique used for the analysis of experimental data must be appropriate for the design and treatment structures of the experiment; failure to take this into account can produce misleading results. This paper illustrates how split‐plot designs can be used for the analysis of robust design experiments. In particular, the polysilicon deposition process data presented by Phadke1is analysed, and comparisons are made between the split‐plot analysis of the raw data and the analysis conducted using signal‐to‐noise ratios. In addition, we demonstrate how the split‐plot analysis provides information about interactions between control and noise factors, and how interaction plots can be used to assess the performance of the control factors across the levels of the noise factors. This information is particularly important to select the settings of the control factors that minimize the variation in the response induced by the nois

ISSN:0748-8017    

DOI:10.1002/qre.4680100207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractEngineering and managerial response to the increased demand for more usable computer products is hindered by lack of relevant knowledge in the majority of current Research and Development environments. This paper proposes to use reinterpretation of the existing reliability engineering knowledge base into the language of design for usability, as a way to speed up acceptance and adoption of human factors engineering tools, methods and expertise into the computer designers' set of core competencies. Described similarities in concepts, definitions, formal models and practical aspects between reliability and usability, justify this proposal.

ISSN:0748-8017    

DOI:10.1002/qre.4680100208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe paper is a report of an investigative study carried out to evaluate the quality of rings manufactured for rolling element bearings. The rings are manufactured from 36–75 mm diameter bars of high‐carbon high‐chromium bearing steel, grade SAE‐52100 conforming to ASTM A295‐1984 in a ring plant, which essentially consists of an induction furnace and a fast‐acting hot forging machine consisting of a set of feed rolls, hot shear and four forming stations. The ring plant is capable of producing 17 million rings per annum. Thus the volume of rings produced is very large and the project was undertaken with the objective of process improvement to build in confidence during the manufacture of the product so that it can be sent out without final inspection. The project was carried out in three phases, namely use of variables charts together with the identification of the causal factors for the ovality of rings with the help of cause‐and‐effect diagrams, followed by process optimization using parameter design, and this, in turn, was followed by on‐line control procedure instituted for the control of the variable which deter

ISSN:0748-8017    

DOI:10.1002/qre.4680100209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThis application note describes a computer‐based method for automated evaluation of Weibull‐distributed life‐time data. It uses comercially available software, MathCad, to set up equations and graphs. The computer application is a simple and non‐expensive way of evaluating and displaying your life‐time data taking into consideration both parametric and non‐parametric confidence intervals. It is valid for arbitrarily ce

ISSN:0748-8017    

DOI:10.1002/qre.4680100210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

ISSN:0748-8017    

DOI:10.1002/qre.4680100211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

ISSN:0748-8017    

DOI:10.1002/qre.4680100212

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY