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Researchers have proposed the dynamic heterogeneous redundancy (DHR) architecture, which integrates dynamic, heterogeneous, redundant, and closed-loop feedback elements into the system, to fortify the reliability of the railway passenger service system (RPSS). However, there are at least two weaknesses with the common DHR architectures: (1) they need system nodes with enough computing and storage resources; (2) they have hardly considered the reliability of DHR architecture. To this end, this paper proposes a double-layer DHR (DDHR) architecture to ensure the reliability of RPSS. This architecture introduces a set of algorithms, which are optimized co-computation and ruling weight optimization algorithms for the data processing flow of the DDHR architecture. This set improves the reliability of the DDHR architecture. For the evaluation of the reliability of DDHR architecture, this paper also proposes two metrics: (1) Dynamic available similarity metric. This metric does not rely on the overall similarity of the double-layer redundant executor sets but evaluates the similarity of their performance under the specified interaction paths within a single scheduling cycle. The smaller its similarity, the higher its reliability. (2) Scheduling cycle under dual-layer similarity threshold. This metric evaluates the reliability of the RPSS under actual conditions by setting the schedulable similarity thresholds between the same and different layers of the dual-layer redundant executives in the scheduling process. Finally, analog simulation experiments and prototype system building experiments are carried out, whose numerical experimental results show that the DDHR architecture outperforms the traditional DHR architecture in terms of reliability and performance under different redundancy and dynamically available similarity thresholds, while the algorithmic complexity and multi-tasking concurrency performance are slightly weaker than that of the DHR architecture, but can be applied to the main operations of the RPSS in general. [ABSTRACT FROM AUTHOR]

The porous media approach is regarded as an appropriate methodology for hydraulic simulations of complex pebble beds in fusion reactors. In order to determine the parameters (permeability α and inertial loss coefficient C) of the porous media accurately, two methods are proposed: the correction method and the fitting method. In this paper, a single-channel model with sequentially packed pebbles is constructed in order to obtain the pressure drop gradient against superficial velocities. Two methods, the correction method and fitting method, are employed to determine the permeability and inertial loss coefficient, and the results are evaluated with comparisons. Based on the results, both the correction method and fitting method are deemed feasible for the parameter determinations. In consideration of the consumption of resources and time for simulation, the fitting method is recommended during the preliminary design phase to shorten the duration of design, while the correction method is suggested to obtain precise results when the design is accomplished. Both of the methods would be evaluated with the data obtained from experiments in the future. [ABSTRACT FROM AUTHOR]

Taking AC power supply system of a mine as research object and combining possible circulation path of AC stray current, a mine AC stray current model was built based on analysis of generation mechanism of mine AC stray current. Distribution laws of AC stray current under different unbalance coefficient of insulation resistance of high voltage or low voltage cable were researched by Matlab/Simulink simulation. The research results show that when insulation resistance of high voltage or low voltage cable is asymmetry, the generated AC stray current mainly distributes in shielding or ground wire and metal net in asymmetry section of insulation resistance. When insulation resistance of the entire cable is asymmetric, AC stray current increases continuously in return path to power grid. With the increase of unbalance coefficient of insulation resistance, effective value of AC stray current flowing through shielding or ground wire, metal net and each ground electrode all increases.

For problem that transmission efficiency of traditional magnetic coupling resonant wireless power transmission system based on single coil structure was limited by transmission distance, a magnetic coupling resonant wireless power transmission system based on variable coil structure was designed. An equivalent circuit model of the system was built, relationship between transmission efficiency and transmission distance were analyzed when the system adopted two-coil and four-coil respectively, and conclusions were gotten as follows: transmission efficiency of the system with two-coil structure decreased with increase of transmission distance, and transmission efficiency of the system with four-coil structure increased first and then decreased with increase of transmission distance. According to above conclusions, a coupling resonant mode using variable coil structure was proposed, which adopted two-coil structure when transmission distance was smaller than coil radius and four-coil structure when transmission distance was larger than coil radius, so as to realize the maximization of transmission efficiency under different transmission distances. The simulation and experimental results verify effectiveness and validity of the system.

In this paper, GIS and RS spatial analysis techniques were used to establish a system for identifying sensitive targets of terrestrial ecosystems in Chishui River Basin, and to identify protection targets of terrestrial ecosystems in different regions. The result shows that the assessment of habitat sensitivity in Chishui River Basin was dominated by non-sensitive areas and highly sensitive areas, which highly sensitive areas account for 60.43% of the basin area, mostly concentrated in the mountainous areas at the junction of Chishui City, Xishui County and Gulin County; non-sensitive areas account for 39.13% and are mosaically distributed with highly sensitive areas; mildly sensitive areas, moderately sensitive areas and extremely sensitive areas account for a total of about 0.5% of the basin area and are more scattered throughout the basin. The distribution is scattered. The moderately sensitive areas in the Chishui River Basin are more than 60.7% of the basin area, indicating that the habitats in the Chishui River Basin are generally sensitive and the ecologically sensitive targets are mainly wooded areas, which need to be protected.