Based on the analysis of the practical measurement data of H-field values at three different sites along the longitudinal direction of the railway, this paper proposes an aerial catenary nonuniform transmission line model to predict longitudinal propagation characteristic of pantograph arcing electromagnetic (EM). According to the theory of EM field, EM emission field value measured at articulated neutral section (ANS) site is converted into the initial current of the contact wire. With the initial current, the current distribution on the contact wire and the EM field distribution along the railway when pantograph slid the ANS could be obtained by the proposed model. The validity of the proposed model is verified by the consistency of the theoretical results and the practical measurement at 0.5 MHz, which is the frequency point of the nondirectional radio beacon (NDB).

There are two cases that can cause cable overvoltage in a high-speed electric multiple units (EMU) system: one is the seriously rusty rail; the other is pantograph arcing, especially when the train passes through the phase separations. Both cases can endanger the normal operation of the EMU. In this paper, a full analysis is given on the mechanism of the electromagnetic interference, corresponding to the conducted and radiated interference. First, the actual circumstances in which the two kinds of interferences generate are described and the equivalent circuit model is established. Then, the two kinds of interference are analyzed and the induced overvoltage is calculated by means of finite-difference time domain method and piecewise-line technique. Next, based on the analysis mentioned above, a specific transient voltage suppressor (TVS) is proposed to be applied at the terminal of a cable in the train. Finally, the results of theoretical calculation, simulation by Computer Simulation Technology, and measurement are obtained and compared, among which a good agreement is achieved. Thus, the validity of the equivalent circuit model and the suppression effect of the TVS on overvoltage excited by conducted and radiated interference are verified.

The high current pulse in traction network is an extreme and dangerous situation, and the short-circuit experiment is to simulate this situation. The short-circuit experiment of traction network has always been very important to detect the safety and stability of high-speed railway (HSR). This article presents an electromagnetic emission (EME) prediction method of the traction network short-circuit experiment. The multiconductor transmission line (MTL) is used to model the traction network, considering the nonuniform distribution of each conductor, the tunnel, and other complex factors. General regression neural network (GRNN) is introduced to simplify the calculation of the parameter matrix in the tunnel. Combined with the finite difference time domain (FDTD) method, the low frequency transient current distribution and EME on the line are predicted, and its accuracy is verified by field test. This method provides a theoretical basis for the evaluation of electromagnetic interference (EMI) of HSR and the protection of surrounding weak current equipment.

Wireless Sensor and Actuator Networks (WSANs) include not only sensor nodes, but also actuator nodes. Since actuators’ capabilities such as moving, communication and event handling require much more energy than sensors, both actuators and sensors are affected by energy and make WSANs encounter serious energy constraints. Although many energy replenishment studies have been proposed for Wireless sensor networks (WSNs), they cannot work well in WSANs. To solve the energy replenishment problem of WSANs, we first analyze the characteristics in WSANs, and then present an actuator energy guaranteed mobile charging scheme (AEG) for WSANs. AEG evaluates the actuator failure risk in the network, and provides charging service for actuators exclusively when there exists an actuator failure risk. Moreover, under the condition that energy safety of actuators is guaranteed, AEG replenishes energy for sensors preferentially, which could avoid sensor failures as much as possible. We evaluate the performance of AEG by simulation, and the results indicate that AEG could reduce sensor failures and achieve lower average charging delay than existing schemes on the basis of ensuring no actuator failure.