The numerous high-power devices and cables gathered around the subway vehicle will aggravate the deterioration of the electromagnetic environment, which may cause the train to fail to operate normally or threaten the health of passengers with a pacemaker or defibrillator. In order to study the distribution characteristics of low-frequency magnetic field of the subway in complex electromagnetic environment and the influence of various factors on human electromagnetic exposure, the magnetic flux density nephograms of the subway train with different vehicle body materials, with or without windows and with the shielding layer are calculated and analyzed. Specific energy absorption rate (SAR) values have been calculated in a standing voxel model from exposure to electromagnetic fields at 2.4 GHz, frequencies commonly used by Wi-Fi devices. The numerical results show that the average value of magnetic flux density in the stainless-steel carriage is less than that in the aluminum alloy carriage and the carbon fiber reinforce plastic (CFRP) carriage. Compared with the vehicle with windows, the average value of magnetic flux density in the vehicle without windows is less. The added shielding layer decreases the average value of magnetic flux density from 10.5 uT to 3 uT. The maximum value of magnetic flux density in the carriage under different factors is about 10 uT, which is far less than the magnetic flux density reference limit of 0.1 mT of the International Commission of Non-Ionizing Radiation Protection (ICNIRP) standard. Whenthe Wi-Fi device is closest to the human body, the highest Specific Absorption Ratio (SAR) value of human tissue is 0.00749 W/kg, which is far less than the electromagnetic exposure limit of 1.6 W/kg of IEEE standard.
1., "EN 60118-4, Electroacoustics - Hearing aids Part 4: Induction-loop systems for hearing aid purposes - System performance requirements,", 2015. doi:10.1109/TEMC.2019.2926393
2., "EN 45502-2-1, Active implantable medical devices - Part 2-1: Particular requirements for active implantable medical devices intended to treat bradyarrhythmia (cardiac pacemakers),", 2003. doi:10.3390/en13051028
3. Xu, M., Y. Wang, X. Li, X. Dong, H. Zhang, H. Zhao, and X. Shi, "Analysis of the influence of the structural parameters of aircraft braided-shield cable on shielding effectiveness," IEEE Trans. Electromagn. Compat., Vol. 62, No. 4, 1028-1036, 2020. doi:10.2528/PIERM18061403
4. Liu, G., P. Zhao, Y. Qin, M. Zhao, Z. Yang, and H. Chen, "Electromagnetic immunity performance of intelligent electronic equipment in smart substations electromagnetic environment," Energies, Vol. 13, No. 5, 2020.
5. Mo, Y., Y. Wang, F. Song, Z. Xu, Q. Zhang, and Z. Niu, "Investigating the impacts of meteorological parameters on electromagnetic environment of overhead transmission line," Progress In Electromagnetics Research M, Vol. 70, 177-185, 2018.
6. Kirsha, A. V. and S. F. Chermoshentsev, "Investigation of the electromagnetic environment in the engine nacelle of an aircraft during the emission of electromagnetic interference from the generator power lines," Int. Rus. Auto. Conf., 1005-1009, 2020.
7. Xie, D., J. Lu, F. Lei, and M. Huang, "Simulation and analysis of radiated electromagnetic environment from cable in cabin," 5th IEEE Int. Symp. MAPE, 534-537, 2013.
8. Yu, Z., X. Wang, R. Zeng, Y. Fu, L. Liu, and M. Li, "Analysis of factors influencing the parameters of electromagnetic environment," Institution of Engineering and Technology, Vol. 2019, No. 16, 2787-2789, 2019.
9. Fady, B., J. Terhzaz, A. Tribak, and F. Riouch, "Integrated miniature multiband antenna designed for WWD and SAR assessment for human exposure," Int. J. Antennas Propag., Vol. 2021, 2021.
10., "ICNIRP statement on the ``Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic elds (up to 300 GHz)''," Health Phys., 2009. doi:10.1109/TEMC.2019.2954111
11., "IEEE standard for safety levels with respect to human exposure to radio frequency electromagnetic fields, 3 kHz to 300 GHz," IEEE Std C95.1, 1999. doi:10.1109/ACCESS.2020.3042002
12. Arduino, A., O. Bottauscio, M. Chiampi, L. Giaccone, I. Liorni, N. Kuster, L. Zilberti, and M. Zucca, "Accuracy assessment of numerical dosimetry for the evaluation of human exposure to electric vehicle inductive charging systems," IEEE Trans. Electromagn. Compat., Vol. 62, No. 5, 1939-1950, 2020. doi:10.1109/TEMC.2016.2626968
13. Migliore, M. D. and F. Schettino, "Power reduction estimation of 5G active antenna systems for human exposure assessment in realistic scenarios," IEEE Access, Vol. 8, 220095-220107, 2020. doi:10.1109/ISEMC.2018.8393732
14. Senic, D., A. Sarolic, C. L. Holloway, and J. M. Ladbury, "Whole-body specific absorption rate assessment of lossy objects exposed to a diffuse field inside a reverberant environment," IEEE Trans. Electromagn. Compat., Vol. 59, No. 3, 813-822, 2017.
15. Sadamitsu, S., S. W. Leung, W. K. Lo, and W. N. Sun, "Practical considerations of human exposure in railway systems," 2018 IEEE International Symposium on Electromagnetic Compatibility and 2018 IEEE Asia-Pacifc Symposium on Electromagnetic Compatibility (EMC/APEMC), 28-31, 2018.
16., "IEEE guide for the measurement of quasi-static magnetic and electric fields," IEEE Std 1460-1996, 1997.
17. Gong, M., "Design, simulation and experimental study on electromagnetic shielding structure of carbon fiber reinforced composites for railway vehicles,", Beijing Jiaotong University, 2019.