Jian Wang

This paper considers the stable tracking problem of high-speed train control systems based on event-triggered control. With the aid of external auxiliary dynamics and the integral signal of the controlled system state, an integral event-triggering condition was designed. The stability of the closed-loop system is obtained through a Lyapunov function by extending the dimension and decaying it at the triggering time point. At the same time, Zeno-like phenomena are also excluded from the closed-loop system. The cooperative control problem of designing separate event-triggering conditions for each train is also considered in this paper. Finally, numerical examples are provided to illustrate the efficiency and feasibility of the theoretical results.

A multi-constellation, multi-frequency Global Navigation Satellite System (GNSS) receiver is capable of simultaneously receiving signals from multiple satellite constellations across various frequency bands. This allows for increased observations, thereby enhancing navigation accuracy, continuity, effectiveness, and reliability. The spread spectrum code structures used in satellite navigation signals differ among systems. Compatible code generators are employed in multi-constellation, multi-frequency GNSS receivers to support tasks such as signal acquisition and tracking. There are three main types of spread spectrum code structures: Linear Feedback Shift Register (LFSR), Legendre sequences, and Memory codes. The Indian Regional Navigation Satellite System (IRNSS) released the L1-SPS (Standard Positioning Service) signal format in August 2023, which utilizes the Interleaved Z4-linear ranging code (IZ4 code) as its spread spectrum code. Currently, there is no universal code generator design compatible with the IZ4 code. In this paper, a proposed universal code generator is based on the hardware structure of the IRNSS IZ4 code generator. It achieves compatibility with all LFSR-based spread spectrum codes and enables parallel generation of multiple sets of GNSS signal spread spectrum codes, thereby improving hardware utilization efficiency. The proposed structure is implemented and validated using FPGA design, and resource consumption is provided as part of the validation results.

Relative to single Global Navigation Satellite System (GNSS) measurements, i.e., the measurements from a single GNSS system, a single GNSS code, and a single GNSS receiver, multi-GNSS measurements for time transfer could improve reliability and provide better short-term stability. Previous studies applied equal weighting to different GNSS systems or different GNSS time transfer receivers, which, to some extent, revealed the improvement in the additional short-term stability from the combination of two or more kinds of GNSS measurements. In this study, the effects of the different weight allocation for multi-measurements of GNSS time transfer were analyzed, and a federated Kalman filter was designed and applied to fuse multi-GNSS measurements combined with the standard-deviation-allocated weight. Tests with real data showed that the proposed approach can reduce the noise level to well below about 250 ps for short averaging times.

Summary: Due to the characteristic of traveling wave dispersion, the wave shape distortion is caused, and the technical difficulty of traveling wave fault location is increased. The frequency analysis and research of the traveling wave signal of the catenary line are presented, based on the wavelet theory and discrete Fourier transform. At first, the frequency information of the traveling wave signal is extracted by DFT, which turns on that the amplitude of each frequency and its distribution characteristics are clarified. Then, the analysis and verification of the traveling wave signal of the catenary line rely on the wavelet theory. The simulation results show that the frequency distribution of the catenary line is obvious, and it has great significance for the further understanding of the characteristics of the traveling wave dispersion and the use of traveling wave ranging technology.