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To address the problems of low time-frequency resolution and cross-term interference in the identification and localization of subway cable defects using time-frequency domain reflectometry (TFDR), this paper proposed a parameterized resampling time-frequency transform (PRTF) method as a time-frequency analysis approach for TFDR test signals. The PRTF method employed a Gaussian-envelope linear frequency modulation signal as the test signal, combined it with a dynamic resampling operator and an adaptive time-frequency atomic decomposition technique, and further introduced a normalized time-frequency cross-correlation function. By extracting time-delay information from local peaks, accurate defect localization was achieved. Simulation experiments were conducted on a flexible control cable in flame-retardant class B1 for subways, and a defect was preset at a distance of 3 900 m from the head end to verify the effectiveness of the proposed method. The results show that compared with the traditional Wigner-Ville distribution (WVD), short-time Fourier transform (STFT), and continuous wavelet transform (CWT) methods, the proposed method achieves a localization error of only 5.5 m, and its time-frequency cross-correlation function curve is free of interference terms. In contrast, the WVD method suffers from significant interference terms, while the localization errors of the STFT and CWT methods both exceed 16 m. The proposed method significantly improves the detection sensitivity and localization reliability of weak local defects in subway cables.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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