Performance degradation simulation of electronic product for reliability analysis
To study analysis method of performance degradation during long term operation based on function simulation, accelerated degradation test was carried out on the power supply module directly, and the test data was used for reliability analysis. As the same time, accelerated degradation test was carried out on the key components in power supply circuit. The test data was injected into the functional simulation model of power supply to simulate performance degradation and analyze reliability. Finally the results of the two kinds of analysis were compared to demonstrate the effectiveness of the proposed simulation method. Comparison shows that average life span of power supply is 281560 hours based on accelerated degradation test while 357290 hours based on degradation simulation. Since only considering degradation of the key components, the result of simulation method is of partial optimism. But the deviation is in a reasonable range, which proved that the method is effective.
Research on reliability assessment of metalized film capacitors based on T performance degradation test
Metalized film capacitor is a kind of product with a long lifetime and high reliability, so it is difficult to assess its lifetime and reliability using the traditional statistical inference based on the large sample of data from the lifetime test. Therefore, first, this paper presents a type of test called T performance degradation test, which is divided into several stages. During the test, the number of capacitors which are still under working conditions decreases stage by stage until the test lasts a long time with very fewer capacitors. Finally, this paper presents a reliability assessment method based on the data from the test. At last, an application on the reliability assessment of the energy system of the laser facility is presented.
Numerical tools applied to power reactor noise analysis
In order to be able to calculate the space- and frequency-dependent neutron noise in real inhomogeneous systems in two-group theory, a code was developed for the calculation of the Green's function (dynamic transfer function) of such systems. This paper reports on the development as well as the test and application of the numerical tools employed. The code that was developed yields the space-dependence of the fluctuations of the neutron flux induced by fluctuating properties of the medium in the two-group diffusion approximation and in a two-dimensional representation of heterogeneous systems, for both critical systems and non-critical systems with an external source. Some applications of these tools to power reactor noise analysis are then described, including the unfolding of the parameters of the noise source from the induced neutron noise, measured at a few discrete locations throughout the core. Other concrete applications concern the study of the space-dependence of the Decay Ratio in Boiling Water Reactors, the noise-based estimation of the Moderator Temperature Coefficient of reactivity in Pressurized Water Reactors, the modeling of the beam- and shell-mode core-barrel vibrations in Pressurized Water Reactors, and the investigation of the validity of the point-kinetic approximation in subcritical systems driven by an external source. In most of these applications, calculations performed using the code are compared with at-power plant measurements. Power reactor noise analysis applications of the above type, i.e. core monitoring without disturbing plant operation, is of particular interest in the framework of the extensive program of power uprates worldwide.