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Through logical analysis of the phenomenon of recovery faults after train arrivals in a semi-automatic receiving station from a departure station, this paper confirms the lighting status of the indicator lights on the console displays of the two stations under fault conditions, observes the operation of the relays in the recovery circuits of the two stations during faults, tests the receiving and sending voltage values and amplitude of the distributing terminal boards in the signal mechanical rooms of the two stations during faults, and observes the time length of the pulse signal. This paper then makes full use of microcomputer to monitor and replay the fault phenomenon, browses and compares the voltage curve status, data, amplitude and pulse time curve status and curve lengths of the negative pulses sent and received by the two stations under the fault conditions, so as to accurately determine the fault range, confirm the fault point, and quickly deal with the fault. [ABSTRACT FROM AUTHOR]

We report the discovery of a sample of 19 low-redshift (z < 0.22) spectroscopically non-Seyfert galaxies that show slow declining mid-infrared (MIR) light curves (LCs), similar to those of tidal disruption event (TDE) candidates with extreme coronal lines. Two sources also showed relatively fast-rising MIR LCs. They consist of a 61 per cent sample of Wide-field Infrared Survey Explorer (WISE) MIR variable non-Seyfert galaxies with Sloan Digital Sky Survey (SDSS) spectra. In a comparison sample of optically selected Seyfert galaxies, the fraction of sources with such a LC is only 15 per cent. After rejecting five plausible obscured Seyfert galaxies with red MIR colours, the remaining 14 objects are studied in detail in this article. We fit the declining part of the LC with an exponential law and the decay time is typically one year. The observed peak MIR luminosities (νLν) after subtracting host galaxies are in the range of a few 1042–1044 erg s−1, with a median of 5 × 1043 erg s−1 in the W2 band. The black hole masses are distributed over a wide range, with more than half between 107 and 108 M⊙, but are significantly different from those of optical/UV selected TDEs. Furthermore, MIR luminosities are correlated with the black hole mass, stellar mass or luminosity of their host bulges. Most galaxies in the sample are red and luminous, with an absolute r magnitude between −20 and −23. We estimate the rate of event as about 10−4 galaxy−1 yr−1 among luminous red galaxies. We discuss several possibilities for variable infrared sources and conclude that most likely they are caused by short sporadic fuelling of supermassive black holes via either the instability of accretion flows or tidal disruption of stars. [ABSTRACT FROM AUTHOR]