Ageing Assessment, Condition Inspection and Lifetime Evaluation for Safety Related Fuse in Nuclear Power Plant

This paper presents the ageing mechanism of fuse in nuclear power plant in detail. Metal Electromigration is identified as the dominant ageing mechanism. On this basis, the dominant status indicators, temperature and resistance of fuse were ensured, and current-temperature curve was proposed. The infrared thermal imaging technology was used to inspect the ageing condition and prove the current-temperature curve. Finally, the accelerated ageing testing was conducted abiding by the dominant ageing mechanism, and the lifetime was evaluated.

Lifetime Evaluating and the Effects of Operation Conditions on Automotive Fuel Cells

Lifetime isone of the important indicators of automotive proton exchange membrane fuel cells. People used to evaluate the lifetime of vehicular fuel cells by laboratory tests or road tests that usually take thousands hours even years. In order to achieve a rapid evaluation technique and to seek lifetime extension methods, a lifetime calculation formation was drawn out in consideration of the vehicle driving cycle and the working condition factors. Bench experiments were individually carried out on two fuel-cell stacks same as ones applied on vehicle, and the performance decay rates of the two stacks were obtained under four operation conditions of changing load cycle, start-stop cycle, idling and heavy load. As a result, the predicted lifetimes rather conform to the actual running status in road test. And the research on the fuel cell performance decay rates under different load conditions was also done. Consequently, an unexpected finding was discovered that operating under micro-current has an effect on recovering fuel cell performance. The vehicle fuel cell rapid assessment method only requires four laboratory tests of driving cycle, load cycle, idle operating conditions and heavy load conditions, and the whole process merely lasts less than 250 h. These experimental results can be used to predict the vehicular fuel cell lifetimes on various utility models or driving cycles, therefore to optimize the application model to prolong the fuel cell lifetime. Actually in the experiment, it has already been proved successfully that the fuel cell lifetime could be extended from 1 100 h to 2 600 h by optimizing operating mode. The quick evaluation method is helpful to develop extended life fuel cell and to deplete fuel cell for a longer time.

Lifetime Evaluation of Medium and Small Size Power Transformers—— Part 1 : Theory

A new methodology that combines analytical and experimental methods is proposed for evaluating transformer lifetime. This first part of a two part series focuses on aging and lifetime evaluation of oil sealed transformers. The second part focuses on an experimental study of the various elements of transformers. A new computational formula based on the degree of polymerization (DP) of the insulation paper is proposed for lifetime evaluation of transformers.

A New Method to Evaluate the Corporation——Experimental Research on the Example of NetEase Company

Most of the Internet or e-commerce corporations have few earnings or even none. The traditional corporation valuation methods don not work well when encountering these types of corporations. Just in these backgrounds, a new method called CVBC model is brought forward to evaluate these types of corporations in our article, which is based on the customer lifetime value. In essence, it extends the concept of customer lifetime value and combined with the traditional financial methods, then creates a new valuation method. It can work well to the corporations, which have been said before. The principle, mathematical model of the method and the effect of the practical application are discussed in detail.

Approach for Reliability Evaluation of Cross-Linked Polyethylene Under Combined Thermal and Vibration Stresses

Based on Wiener process model, a new approach for reliability evaluation of cross-linked polyethylene(XLPE) is proposed to improve the lifetime evaluation reliability of XLPE under multi-stressing conditions and study the failure probability distribution. In this paper, two accelerated aging tests are carried out under combined thermal and vibration conditions. The volume resistance degradation data of XLPE samples are tested with a24 h interval under the accelerated stressing conditions at(130℃, 12 m/s^2) and(150℃, 8.5 m/s^2), respectively.Nonlinear degradation data obtained from the experiment are transformed to linear intermediate-variable values using time scaling function, and then linearized degradation data are calculated and evaluated on the basis of linear Wiener process model. Considering traditional Arrhenius equation and inverse power criterion, parameters of the linear Wiener model are estimated according to the maximum likelihood function. The relationship curves on probability density and reliability are given, and the lifetime distribution of XLPE under different stressing conditions is also obtained for evaluating the reliability of XLPE insulation. Finally, the life expectancy of XLPE is 17.9 a under an allowance temperature of 90℃ and an actual vibration acceleration of 0.5 m/s^2. The approach and results in this paper may be used for reliability assessment of high-voltage multiple samples or apparatuses.