Airport Lighting Aid is important for guaranteeing -off and landing. This paper mainly analyzed the reliability of Airport Lighting System when light source fails. With the data obtained from airfield lighting station in an Airport in China, this paper predicted the reliability of every subsidiary system, built up the fault tree and calculated the reliability of airport lighting aid system. The conclusion in this paper is a useful reference for fault prediction and repairment of airport lighting aid system.
Finite-element method (FEM) has been widely used in industrial applications for many years. With the increase of finite-element model complexity and the number of elements, computation burden has become a serious issue and requires more attention. In this paper, the transmission line method (TLM) is adopted to the solution of FEM-based nonlinear axisymmetric magnetostatic problem and an equivalent finite-element network's circuit model is given. Several methods were investigated to speed up the computation, such as Newton preconditioners, simplification of nonlinear equation solution and parallel computation. Compared with traditional Newton FEM iteration, our results show that the proposed method has more obvious advantages on computational efficiency at the same calculation accuracy. The method is applicable and valuable in the characteristic analysis and design of the magnetic device with a cylindrical structure.
Contact resistance of the main circuit is an important parameter for measuring the performance and reliability of relay products. The contact resistance value interacts with the stress and temperature of the contact surface during the relay's operation, and it will change with the ambient temperature and load current. Therefore, it is difficult to calculate the contact resistance when the relay is in the working environment. However, the finite element model used to predict contact resistance in previous studies does not consider the effect of current and temperature on the contact surface stress at the microscopic level. In this paper, based on the fractal theory, we established three-dimensional electrical contact finite element models in micrometer-scale and nano-scale to solve the contradiction between the computational efficiency and accuracy of the finite element model containing fractal surfaces. In the microscopic electrical contact model, the multi-physics coupling process of electric-temperature-stress at the conductive spot is analyzed, to improve the accuracy of the calculation of the local contact resistance at the conductive spot. Through the data transfer between the macroscopic finite element temperature rise model of the relay and the microscopic electrical contact model, the temperature rise and contact resistance of the relay under different load currents are calculated more accurately. The feasibility of the simulation method is proved by comparison with experimental measurement results. INDEX TERMS Contact resistance, finite element analysis, fractals, multi-physics coupling, multiscale.
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