共查询到20条相似文献，搜索用时 15 毫秒
1.
Zhi Lin Chong Amitava Mukherjee Marco Marozzi 《Quality and Reliability Engineering International》2021,37(1):242-261
The distribution of consumer lifetimes, high-voltage of current in semiconductor transistors, and the risk associated with monitoring health care often come with a threshold. A two-parameter (or shifted) exponential distribution is, in general, regarded as a better statistical model in such situations compared with a traditional (one-parameter) exponential model. Research on inferential problems associated with two-parameter exponential distributions, including monitoring schemes for the parameters of this model, is active. Currently, all existing monitoring schemes for origin and scale parameters of a shifted exponential distribution assume that the process parameters are known (Case-K). The actual values of the process parameters are, however, rarely known in practice. The traditional method of estimating parameters from a set of a (Phase-I) reference sample and plug them in for Phase-II monitoring affects the performance of a monitoring scheme. Skewed processes, like the two-parameter exponential process, exacerbate this problem. The present article shows that even a reference sample of size 50,000 cannot guarantee nominal in-control performances of monitoring schemes when the actual process parameters are unknown (Case-U). To address this problem, we develop monitoring schemes based on max and distance statistics for simultaneously monitoring the two parameters of a shifted exponential process in Case-U. We show that the proposed schemes perform well. We illustrate the practical application of the proposed procedures by analyzing data about the production of an electronic component. 相似文献
2.
Tsai‐Hung Fan Cian‐Huei Chen 《Quality and Reliability Engineering International》2017,33(7):1417-1424
Degradation modeling might be an alternative to the conventional life test in reliability assessment for high quality products. This paper develops a Bayesian approach to the step‐stress accelerated degradation test. Reliability inference of the population is made based on the posterior distribution of the underlying parameters with the aid of Markov chain Monte Carlo method. Further sequential reliability inference on individual product under normal condition is also proposed. Simulation study and an illustrative example are presented to show the appropriateness of the proposed method. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
3.
Chenglong Li Amitava Mukherjee 《Quality and Reliability Engineering International》2019,35(6):1846-1865
Traditional Duncan‐type models for cost‐efficient process monitoring often inflate type I error probability. Nevertheless, controlling the probability of type I error or false alarms is one of the key issues in sequential monitoring of specific process characteristics. To this end, researchers often recommend economic‐statistical designs. Such designs assign an upper bound on type I error probability to avoid excessive false alarms while achieving cost optimality. In the context of process monitoring, there is a plethora of research on parametric approaches of controlling type I error probability along with the cost optimization. In the nonparametric setup, most of the existing works on process monitoring address one of the two issues but not both simultaneously. In this article, we present two distribution‐free cost‐efficient Shewhart‐type schemes for sequentially monitoring process location with restricted false alarm probability, based, respectively, on the sign and Wilcoxon rank‐sum statistics. We consider the one‐sided shift in location parameter in an unknown continuous univariate process. Nevertheless, one can easily extend our proposed schemes to monitor the two‐sided process shifts. We evaluate and compare the actual performance of the two monitoring schemes employing extensive computer simulation based on Monte Carlo. We investigate the effects of the size of the reference sample and the false alarm constraint. Finally, we provide two illustrative examples, each based on a realistic situation in the industry. 相似文献
4.
Muhammad Taqi Shah Muhammad Azam Muhammad Aslam Uzma Sherazi 《Quality and Reliability Engineering International》2021,37(2):785-803
Modern and emerging techniques of technology have brought a revolution in quality inspection of products. When events in highly efficient production processes occur rarely, it requires to inspect and monitor the time between occurrence of these events (TBE). The exponential and gamma distributions are commonly used models for time between events (TBE) data. In this article, a new monitoring scheme has been established for TBE data based on exponential and gamma distributions. In a previous research, transformation-based control charts have been developed for TBE. The proposed study is aimed to use the exact probability distribution of charting statistic rather than applying transformations to data and this has remained still unaddressed. Average run length (ARL) and percentage decrease in ARL (ΔARL) have been calculated using Monte Carlo simulations and the proposed monitoring method has been compared with existing techniques applied to transformed data. The proposed scheme provides a simpler design structure and better performance on different sample sizes in identifying annoying process variations. Further, the technique has been applied to simulated and real-life data sets of time between manufacturing plant accidents to highlight the worth and particle applicability of the proposed work. 相似文献
5.
Syed Muhammad Muslim Raza Ahmed Faisal Siddiqi 《Quality and Reliability Engineering International》2017,33(2):387-399
Exponentially weighted moving average (EWMA) control charts are consistently used for the detection of small shifts contrary to Shewhart charts, which are commonly used for the detection of large shifts in the process. There are many interesting features of EWMA charts that have been studied for complete data in the literature. The aim of present study is to introduce and compare the double exponentially weighted moving average (DEWMA) and EWMA control charts under type‐I censoring for Poisson‐exponential distribution. The monitoring of mean level shifts using censored data is of a great interest in many applied problems. Moreover, a new idea of conditional median is introduced and further compared with the existing conditional expected values approach for monitoring the small mean level shifts. The performance of the DEWMA and EWMA charts is evaluated using the average run length, expected quadratic loss, and performance comparison index measures. The optimum sample size comparisons for the specified and unspecified parameters are also part of this study. Two applications for practical considerations are also discussed. It is observed that different censoring rates and the size of shifts significantly affect the performance of the EWMA and DEWMA charts. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
6.
Paul W. Mielke 《技术计量学》2013,55(1):84-85
A conditional method of inference is used to derive exact confidence intervals for several life characteristics such as location, scale, quantiles, and reliability when the data are Type II progressively censored. The method is shown to be feasible and practical, although a computer program may be required for its implementation. The method is applied for the purpose of illustration to the extreme-value and the one- and two-parameter exponential models. Prediction limits for the lifelength of future units are also discussed. An example consisting of data from an accelerated test on insulating fluid reported by Nelson is used for illustration and comparison. 相似文献
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Mixture models are receiving considerable significance in the last years. Practical situations in reliability and survival analysis may be addressed by using mixture models. When making inferences on them, besides the estimates of the parameters, a sensitivity analysis is necessary. In this paper, a general technique to estimate local prior sensitivities in finite mixtures of distributions from natural exponential families having quadratic variance function (NEF-QVF) is proposed. Those families include some distributions of wide use in reliability theory. An advantage of this method is that it allows a direct implementation of the sensitivity measure estimates and their errors. In addition, the samples that are drawn to estimate the parameters in the mixture model are re-used to estimate the sensitivity measures and their errors. An illustrative application based on insulating fluid failure data is shown. 相似文献
9.
In this paper, control charts for monitoring the exponential type‐II censoring samples are investigated. Such data are very common in many practical inspection scenarios in reliability context when items are replaced in groups after a period of time. The average time to signal, which involves both the number and the time of samples inspected until a signal occurs, is a good criterion to evaluate the performance of control charts. We propose an average time to signal‐unbiased control chart with known parameter and compare the proposed method with the traditional ones. The results indicate the proposed control chart is more sensitive to system deterioration. Then the effects of parameter estimation on the proposed control charts are evaluated. Because the control limits with estimated parameters result in more false alarms, an adjusted control chart with estimated parameters is proposed and the self‐starting control chart based on a sequential sampling scheme is adopted to solve the phase I problem. Finally, two examples are given to illustrate the implementation of the proposed approach. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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A. Audu O. O. Ishaq R.V.K. Singh A. Danbaba F. Manu 《Quality and Reliability Engineering International》2023,39(1):190-205
This study aimed at enhancing the efficiency of Zaman estimators using exponential transformation technique. A new class of estimators was obtained using the concept of Bahl and Tuteja. The bias and mean squared error (MSE) of the new class of suggested estimators was derived up to second degree approximation. The empirical study through simulations was conducted using Normal, exponential, gamma, chi-square and beta distributions under robust regression methods (Huber-M, Huber-MM, LTS (least trimmed squares) and LMS (least median of squares)) and the results revealed that proposed estimators were more efficient. 相似文献
12.
In many situations, the times between certain events are observed and monitored instead of the number of events particularly when the events occur rarely. In this case, it is common to assume that the times between events follow an exponential distribution. Control charts are one of the main tools of statistical process control and monitoring. Control charts are used in phase I to assist operating personnel in bringing the process into a state of statistical control. In this paper, phase I control charts are considered for the observations from an exponential distribution with an unknown mean. A simulation study is carried out to compare the in‐control robustness and out‐of‐control performance of the proposed chart. It is seen that the proposed charts are considerably more in‐control robust than two competing charts and have comparable out‐of‐control properties. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
13.
G. S. Lingappaiah 《TEST》1990,5(1):27-37
Summary This paper deals with the problem of prediction of the order statistics in a future sample. Underlying model is exponential.
Outlier is present in the sample drawn and the sample size is considered a random variable. Firstly, an outlier of type πδ
in the exponential model, is trated. Actual predictive distribution of the order satstistics is obtained. As an extension,
two sample problem is also taken up. Finally, an outlier of type π+δ is dealt and now the predictive distribution is expressed
in terms of hypergeometric functions. 相似文献
14.
Tibor Jacob Hajagos Chao Liu Nerine J. Cherepy Qibing Pei 《Advanced materials (Deerfield Beach, Fla.)》2018,30(27)
The need for affordable and reliable radiation detectors has prompted significant investment in new radiation detector materials, due to concerns about national security and nuclear nonproliferation. Plastic scintillators provide an affordable approach to large volume detectors, yet their performance for high‐energy gamma radiation is severely limited by the small radiation stopping power inherent to their low atomic number. Although some sensitization attempts with organometallics were made in the 1950s to 1960s, the concomitant decrease in light yield has limited the usefulness of these sensitized detectors. Recently, with new knowledge gained during the rapid development of organic optoelectronics and nanotechnology, there has been a revived interest in the field of heavy element sensitized plastic scintillators. Here, the recent efforts on sensitized plastic scintillators are summarized. Basic scintillator physics is first reviewed. The discussion then focuses on two major thrusts in the field: sensitization with: (1) organometallics and (2) oxide and fluoride nanoparticles. The design rationales and major results are examined in detail, with existing limitations and possible future pathways discussed. Special attention is paid to the underlying energy deposition and transfer processes, as these determine the key performance metrics such as light yield and radioluminescence decay lifetime. 相似文献
15.
多元Marshall～Olkin型指数分布的特征及其参数估计 总被引：4，自引：0，他引：4
导出了多元Marshall～Olkin型指数分布的一个特征,利用该特征,获得了多元Marshall～Olkin型指数分布参数的最大似然估计及矩估计. 相似文献
16.
B. Boroomand S. Soghrati B. Movahedian 《International journal for numerical methods in engineering》2010,81(8):971-1018
In this paper, exponential basis functions (EBFs) are used in a boundary collocation style to solve engineering problems whose governing partial differential equations (PDEs) are of constant coefficient type. Complex‐valued exponents are considered for the EBFs. Two‐dimensional elasto‐static and time harmonic elasto‐dynamic problems are chosen in this paper. The solution procedure begins with first finding a set of appropriate EBFs and then considering the solution as a summation of such EBFs with unknown coefficients. The unknown coefficients are determined by the satisfaction of the boundary conditions through a collocation method with the aid of a consistent and complex discrete transformation technique. The basis and various forms of the transformation have been addressed and discussed. We shall propose several strategies for selection of EBFs with the aid of the basis explained for the transformation. While using the transformation, the number of EBFs should not necessarily be equal to (or less than) the number of boundary information data. A library of EBFs has also been presented for further use. The effect of body forces is included in the solution via construction of particular solution by the use of the discrete transformation and another series of EBFs. A number of sample problems are solved to demonstrate the capabilities of the method. It has been shown that the time harmonic problems with high wave number can be solved without much effort. The method, categorized in meshless methods, can be applied to many other problems in engineering mechanics and general physics since EBFs can easily be found for almost all problems with constant coefficient PDEs. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
17.
Fu‐Kwun Wang 《Quality and Reliability Engineering International》2016,32(1):69-78
Comparing two suppliers for linear profiles is a very important task for supplier management. The difference test statistic based on the process‐yield index is proposed to tackle the better process selection for linear profiles. A simple form of the sampling distribution of the process‐yield index is derived by a simulation study. Therefore, the asymptotic normal distribution of the difference test statistic is established. The results provide useful information to practitioners. An example from the leather industry is presented to illustrate the applicability of the proposed method. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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David Han 《Quality and Reliability Engineering International》2019,35(5):1297-1312
Thanks to continuously advancing technology and manufacturing processes, the products and devices are becoming highly reliable. However, performing the life tests of these products at normal operating conditions becomes extremely difficult, if not impossible, due to their long life spans. This can result in missed opportunities to introduce the products to the market in a timely manner and eventually loss of the market share. This problem is solved by accelerated life tests where the test units are subjected to higher stress levels than the normal usage level so that information on the lifetime parameters can be obtained more quickly. The lifetime at the design condition is then estimated through extrapolation using a regression model. In this work, the design optimization of a simple step‐stress accelerated life test under progressive type I censoring is studied with nonuniform step durations for assessing the reliability characteristics of a solar lighting device. Allowing the intermediate censoring to take place at the stress change time point, the nature of the optimal stress duration is demonstrated under various design criteria including D‐optimality, C‐optimality, A‐optimality, and E‐optimality. The existence of these optimal designs is investigated in detail for exponential lifetimes with a single stress variable, and the effect of the intermediate censoring proportion is assessed on the design efficiency. 相似文献
20.
Duangporn Jearkpaporn Douglas C. Montgomery George C. Runger Connie M. Borror 《Quality and Reliability Engineering International》2003,19(6):477-491
A model‐based scheme is proposed for monitoring multiple gamma‐distributed variables. The procedure is based on the deviance residual, which is a likelihood ratio statistic for detecting a mean shift when the shape parameter is assumed to be unchanged and the input and output variables are related in a certain manner. We discuss the distribution of this statistic and the proposed monitoring scheme. An example involving the advance rate of a drill is used to illustrate the implementation of the deviance residual monitoring scheme. Finally, a simulation study is performed to compare the average run length (ARL) performance of the proposed method to the standard Shewhart control chart for individuals. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献