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In statistical process control, Gamma control charts are often designed for time-between-events (TBEs) monitoring. For Gamma distribution, the traditional equal-tail probability limits lead to the problem that some out-of-control events may occur in higher probability than in-control events. To overcome this problem, Gamma control limits with known parameters are proposed based on the narrowest confidence...
Establishing reliability goals is a crucial aspect of achieving and maintaining acceptable reliability performance. Ultimately, the level to which a utility's reliability must aspire is expressed as a set of goals reflecting the needs of a utility's stakeholders. Some of these stakeholders include residential/commercial/industrial customers, regulators and investors.
This article proposes an integrated scheme (T&TCUSUM chart) which combines a Shewhart T chart and a TCUSUM chart (a CUSUM-type T chart) to monitor the time interval T between the occurrences of an event or the time between events (TBE). The performance studies show that the T&TCUSUM chart can effectively improve the overall performance over the entire T shift range. On average, it is more...
CUSCORE control chart is designed based on the thought of CUSCORE statistic to control the non-stationary autocorrelated process IMA (1, 1). The MMSE method is used to remove the auto-correlation among the observations. By comparing the performance of CUSCORE control chart to Shewhart Control Chart, the CUSCORE control is more effective in the case of the process mean drifting.
Great advances in microelectronics failure physics, process reliability, reliability test and evaluation and failure analysis technologies have been achieved in China recently. Some of the significant achievements include the hot-carrier injection (HCI) degradation model, gate oxide TDDB, negative bias temperature instability (NBTI) of very deep sub-micro(VDSM) devices, process quality parameter monitoring...
This paper discusses the use of weighted variance (WV) in setting up the limits of the exponentially weighted moving average (EWMA) chart for the monitoring of the mean of a process from a skewed population. This chart, called the WV-EWMA chart hereafter, reduces to the standard EWMA chart when the underlying distribution is symmetric. The Type-I and Type-II errors of the WV-EWMA chart are compared...
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