| Project/Area Number |
15510134
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Social systems engineering/Safety system
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| Research Institution | Kyusyu Institute of Technology |
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Principal Investigator |
HIROSE Hideo Kyusyu Institute of Technology, Fac.of Computer Science and Systems Engineering, Professor, 情報工学部, 教授 (60275401)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | accelerated life test / remaining lifetime / inspection / Weibull distribution / cumulative exposure model / power law / step-up test / conditional distribution / power law (べき乗則) / step-up test (上昇法) |
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| Research Abstract |
Accelerated life tests using the brand-new electrical insulation have long been used to estimate the lifetime of the insulation. Although a variety of types of stresses are imposed on the insulation in the accelerated life tests, the insulation is often broken more quickly than the estimated lifetime due to unexpected deterioration factors. The step-up breakdown voltage tests using the working insulation are then performed to assess the actual remaining lifetime of the insulation. However, theoretical explanations of the relation between these two test methods have not been made rigorously. One way to combine these two may be the cumulative exposure model proposed by Nelson, or Sedyakin model which is usually applied to short time accelerated life testing.
In studying the cumulative exposure model, we have found a variety of difficulties in parameter estimation for the model; thereby this fact leads us to study first the breakdown voltage estimation using the step-up method. The step-up
… More
method is used to estimate the impulse breakdown voltages when the electrical insulation is not usable after it is broken. We analyses the reliability of the estimates of the underlying breakdown probability distribution in the step-up method, when (1)the observed breakdown voltage itself is available and (2)it is not available. The former case has many advantages compared to the latter case such that (1)the confidence intervals of the estimates become smaller and (2)the estimates can be obtained in stable. We summarize the results of the three cases that the underlying probability distribution for the breakdown voltage is assumed to be normal, Weibull, and gumbel types. The optimal test method is simply and clearly described for various distribution models. The new step-up test method is recommended when the underlying probability distribution is assumed to be some reliability distribution models. We first recommend the use of the parameters of the underlying probability distribution. Second, it is advantageous to use the new step-up method if the observed breakdown voltage itself rather than the two-valued information of breakdown and non-breakdown is available. Using the new step-up method, the number of test specimens can be substantially reduced comparing to that in the conventional step-up method to obtain the same estimation reliability. The optimal strategy of the step-up test to obtain the 50% breakdown voltage is to set the step-up distance to larger than the half of the standard deviation of the underlying distribution. Less
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