A challenge for developing acoustic metamaterials (AMMs) is considering the application of broadband muffling and load bearing capacity simultaneously. In this paper, a honeycomb based graded AMM muffler is proposed, which can widen the attenuation band and improve the structural stiffness without any external device by means of integrated design. Firstly, the acoustic and mechanical characteristics of the muffler unit cell are theoretically and numerically studied, and the graded muffler is designed based on these characteristics. The numerical results show that the graded muffler widens the attenuation bandwidth of the unit cell, and the simulation also shows that the graded muffler has greater stiffness than the uniform one. The stiffness driven muffler provides new possibilities for the design of advanced metamaterial with simultaneous sound insulation and load bearing performances.

Q235 steel is widely used in engineering and construction. Therefore, it is important to identify the damage mechanism and the acoustic emission (AE) response of the material to ensure the safety of structures. In this study, an AE monitor system and an in situ tensile test with an optical microscope were used to investigate the AE response and insight into the damage process of Q235 steel. The surface of the specimen was polished and etched before the test in order to improve the quality of micrographs. Two kinds of AE responses, namely a burst and a continuous signal, were recorded by the AE monitor system during the test. Based on the in situ test, it was observed that the damage of Q235 steel was induced by the crystal slip and the inclusion fracture. Since the crystal slip was an ongoing process, continuous AE signals were produced, while burst AE signals were possibly produced by the inclusion fracture which occurred suddenly with released higher energy. In addition, a great number of AE signals with high amplitude were observed during the yielding stage and then the number and amplitude decreased.

The problem of large speed loss exists in the traditional passing through the electric phase-separation method of trains, which is more prominent when trains pass through an electric phase-separation zone in the uphill section of long ramps and may lead to the trains not passing through the phase-separation zone safely. In order to solve this problem, based on the energy storage type railroad power conditioner, a train uninterrupted phase-separation passing system based on the energy storage type railroad power conditioner is proposed. The energy storage railroad power conditioner can realize the recovery and utilization of regenerative braking energy of the electrified railroad. In the structure of the energy storage railroad power conditioner, the single-phase inverter is led from the middle DC side of the energy storage railroad power conditioner and connected to the neutral line through theLCLfilter and the step-up transformer, which constitutes an uninterrupted phaseseparation passing system. The single-phase inverter is controlled using virtual synchronous generator technology, which allows the single-phase inverter to have external characteristics similar to those of a synchronous generator, providing support for the voltage and frequency in the neutral zone. The power required by the train to pass the electric phase-separation is provided by the power supply arm or the energy storage system, which not only improves the utilization rate of regenerative braking energy but also realizes the uninterrupted phaseseparation passing of the train through the control of the voltage in the neutral region.