Jianhua Liu

This paper proposes a new prediction method for damages such as spalling and wear of heavy haul railways caused and deteriorated easily by the continuous rail-wheel contact during the high intensity and heavy load transportation. Based on the combined model of PCA and TCN-Attention, it is capable of accurately predicting the deterioration trend of spalling damage for heavy haul railways. Firstly, a feature set with high dimension is constructed with the features of time domain and frequency domain extracted from the original vibration signal of rail damage. Secondly, PCA is used to reduce the dimension of the high-dimensional feature set of rail damages. The first principal component is used as the health indicator of rail damages. Further, the TCN-Attention model is adopted to predict the deterioration trend of the rail spalling damage. Finally, the feasibility of the proposed method is verified by using the vibration data of the life cycle of a rail track, from normal working to damaged to failure, collected from a railway depot. The results of the proposed method are also compared with those of prediction models constructed by TCN, LSTM and GRU networks. The comparison shows that the proposed method has better performance and higher prediction accuracy. The proposed method can more accurately predict the deterioration trend of the rail spalling damage.

For the multi-motor traction finite-time control (FTC) system with input saturation constraints, considering parameter simplification of “adding a power integrator” (AAPI) and anti-windup (AW), a total-amount coordinated tracking control (TACTC) strategy based on nonsingular terminal sliding mode (NTSM) is proposed to ensure the global finite-time stability and effectively reduce energy consumption. First, a traction model of multiple permanent magnet synchronous motors (PMSMs) with uncertain parameter perturbations and external disturbances was established. Next, a finite-time auxiliary AW system was designed and the auxiliary state was fed back to TACTC. Then, the strong constraint of parameters of AAPI was relaxed, the setting rules of the corresponding parameters were given and the proof of finite-time Lyapunov stability was completed. Finally, the excellent performance of parameter simplification of AAPI and the controller was verified by the Matlab/Simuink simulation and RT-Lab semi-physical experiment of the multi-motor traction system, which shows that the control strategy can suppress the input saturation effect in the multi-motor traction system effectively.

An optimal utilization of adhesion force based on extremum seeking with sliding mode (SMES) and asymmetric barrier Lyapunov function (ABLF) is proposed for heavy-haul electric locomotives (HHELs), which can eliminate the wheel skidding at optimal adhesion point and achieves maximum traction for HHELs. First, the state equation of wheel-rail adhesion control system is described. The optimal utilization of adhesion force and anti-slip control are analyzed considering the condition changes at the wheel-rail surface. Then, the nonsingular terminal sliding mode observer (NTSMO) is designed to achieve the accurate adhesion coefficient of the wheel-rail. Finally, the SMES method for HHEL is developed to obtain the optimal slip speed and the maximum adhesion coefficient of the uncertain wheel-rail surface. Meanwhile, the ABLF controller is designed to achieve anti-slip control for HHELs in the optimal adhesion state. Comparing with the conventional differential acceleration control (DAC) method, the simulations and experiments verify that the proposed method can achieve optimal adhesion anti-slip control with quick dynamic response, and the HHEL achieves maximum traction.

LTE-A (Long Term Evolution-Advanced) is a 3GPP standard which is an advancement to Long Term Evolution (LTE) and a predecessor of 4G. The rapid development of LTE-A, with a growing base of users, makes it a potential and promising target for covert channels. In this paper, we propose a novel covert channel, called LaSPsteg, designed for LTE-A systems. This method leverages the SN (Sequence Number) field in the header of PDU (Packet Data Unit) to choose covert packets. Then the padding bits in the payload of PDU of chosen packets are used to carry secret information. Specifically, we utilize a pre-shared hash function and an independent variable parameter to achieve varying embedding rules thus ensure the flexibility of our proposed covert channel.