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The low-frequency oscillation (LFO) has occurred in the train–network system due to the introduction of the power electronics of the trains. The modeling and analyzing method in current researches based on electrified railway unilateral power supply system are not suitable for the LFO analysis in a bilateral power supply system, where the trains are supplied by two traction substations. In this work, based on the single-input and single-output impedance model of China CRH5 trains, the node admittance matrices of the train–network system both in unilateral and bilateral power supply modes are established, including three-phase power grid, traction transformers and traction network. Then the modal analysis is used to study the oscillation modes and propagation characteristics of the unilateral and bilateral power supply systems. Moreover, the influence of the equivalent inductance of the power grid, the length of the transmission line, and the length of the traction network are analyzed on the critical oscillation mode of the bilateral power supply system. Finally, the theoretical analysis results are verified by the time-domain simulation model in MATLAB/Simulink.

Prefabricated concrete sandwich panels are crucial components in the construction of prefabricated buildings, providing essential functions such as load-bearing capacity, thermal insulation, and fire resistance. The development of sandwich panels is oriented toward achieving lightweight, high-strength structures with superior thermal insulation properties. This study introduces two types of innovative sandwich panels using TRM rib with FRP composite bolts and FRP pultruded profiles as connectors, respectively. Comprehensive experiments were conducted to evaluate their construction methods and flexural performance with different thicknesses (i.e., 100 mm and 150 mm). The test results indicate that the proposed sandwich panels can be fabricated in large dimensions of 4 m × 3 m and can withstand substantial equivalent wind loads. The different sandwich panels exhibited distinct failure modes and various composite actions of 8.04 %, 28.36 %, 49.56 %, and 85.67 %. Subsequently, this work presents a theoretical analysis model for predicting the initial stiffness, which has achieved favorable accuracy. Comparative analysis with other studies indicates that the sandwich panels investigated are classified as lightweight, high-strength and thin sandwich panels, which demonstrate significant potential for practical applications.