In recent years, there has been rapid growth of Chinese rail transit networks. Many of these networks require elevated bridges. This results in a bridge-borne noise source, which occurs in addition to the main noise s...In recent years, there has been rapid growth of Chinese rail transit networks. Many of these networks require elevated bridges. This results in a bridge-borne noise source, which occurs in addition to the main noise source （i.e., wheel-rail interactions）. Bridge-borne noise is attracting increasing attention because of its low-frequency noise characteristics. This review paper first analyzes the space distribution, spectral characteristics, and sound pressure levels of noise radiated by all-concrete, steel- concrete composite, and all-steel bridges, mainly according to experimental studies. Second, this paper reviews exist- ing theoretical prediction models of noise emanating from bridges： the semianalytical method, the Rayleigh integral method, the boundary element method, and statistical energy analysis. Several case studies are reviewed, and their results are discussed. Finally, according to the results of the current review, the main factors affecting bridgeborne noise are analyzed, several noise reduction measures are proposed for different types of bridges, and their effectiveness is demonstrated.展开更多
Owning to good mechanical properties,steel–concrete composite(SCC)and prestressed concrete(PC)box girders are the types of elevated structures used most in urban rail transit.However,their vibro-acoustic differences ...Owning to good mechanical properties,steel–concrete composite(SCC)and prestressed concrete(PC)box girders are the types of elevated structures used most in urban rail transit.However,their vibro-acoustic differences are yet to be explored in depth,while structure-radiated noise is becoming a main concern in noise-sensitive environments.In this work,numerical simulation is used to investigate the vibration and noise characteristics of both types of box girders induced by running trains,and the numerical procedure is verified with data measured from a PC box girder.The mechanism of vibration transmission and vibro-acoustic comparisons between SCC and PC box girders are investigated in detail,revealing that more vibration and noise arise from SCC box girders.The vibration differences between them are around 7.7 dB(A)at the bottom plate,19.3 dB(A)at the web,and 6.7 dB(A)at the flange,while for structure-radiated noise,the difference is around 5.9 dB(A).Then,potential vibroacoustic control strategies for SCC box girders are discussed.As the vibro-acoustic responses of two types of girders are dominated by the force transmitted to the bridge deck,track isolation is better than structural enhancement.It is shown that using a floating track slab can make the vibration and noise of an SCC box girder lower than those of a PC box girder.However,structural enhancement for the SCC box girder is extremely limited in effects.The six proposed structural enhancement measures reduce vibration by only 1.1–3.6 dB(A) and noise by up to1.5 dB(A).展开更多
The multi-port energy router(ER)is an effective topology for integrating train traction load,AC load,the energy storage system and photovoltaic(PV)energy.The start and stop process of urban rail transit trains and the...The multi-port energy router(ER)is an effective topology for integrating train traction load,AC load,the energy storage system and photovoltaic(PV)energy.The start and stop process of urban rail transit trains and the access of distributed energy sources to rail transit ER lead to serious fluctuations of DC bus power,so it is necessary to route energy between different ports,involving multi-operating modes,while seamless switching is a major challenge.In this paper,a hierarchical coordinated control strategy is proposed to enable the multi-port ER to operate in a coor-dinated fashion under the conditions of train parking,acceleration,constant power driving and deceleration,and to switch seamlessly under various working conditions.The energy central dispatching layer sends working condi-tion instructions by sampling the state information of each port,while the microgrid control layer adopts central-ized control,receiving upper working condition instructions and sending drive signals to the local control layers to maintain the balanced energy flow of each port.In the local control layers,the PV adopts the improved perturbation and observation method of power control(PC-P&O),while the ES system adopts voltage loop control with an SOC influence factor,voltage loop control with switching factor and power loop control according to the different working conditions,so as to transmit the required train load power accurately and maintain the stability of the DC bus voltage.Finally,the effectiveness of the proposed hierarchical coordination control is verified by MATLAB/Simulink simulations.展开更多
基金financial support from the National Natural Science Foundation of China(Grant Nos.51308469 and 51378429)the International Cooperation Program of Sichuan Province(Grant No.2016HH0076)
文摘In recent years, there has been rapid growth of Chinese rail transit networks. Many of these networks require elevated bridges. This results in a bridge-borne noise source, which occurs in addition to the main noise source （i.e., wheel-rail interactions）. Bridge-borne noise is attracting increasing attention because of its low-frequency noise characteristics. This review paper first analyzes the space distribution, spectral characteristics, and sound pressure levels of noise radiated by all-concrete, steel- concrete composite, and all-steel bridges, mainly according to experimental studies. Second, this paper reviews exist- ing theoretical prediction models of noise emanating from bridges： the semianalytical method, the Rayleigh integral method, the boundary element method, and statistical energy analysis. Several case studies are reviewed, and their results are discussed. Finally, according to the results of the current review, the main factors affecting bridgeborne noise are analyzed, several noise reduction measures are proposed for different types of bridges, and their effectiveness is demonstrated.
基金This study was supported by the National Natural Science Foundation of China(Nos.51778534 and 51978580).
文摘Owning to good mechanical properties,steel–concrete composite(SCC)and prestressed concrete(PC)box girders are the types of elevated structures used most in urban rail transit.However,their vibro-acoustic differences are yet to be explored in depth,while structure-radiated noise is becoming a main concern in noise-sensitive environments.In this work,numerical simulation is used to investigate the vibration and noise characteristics of both types of box girders induced by running trains,and the numerical procedure is verified with data measured from a PC box girder.The mechanism of vibration transmission and vibro-acoustic comparisons between SCC and PC box girders are investigated in detail,revealing that more vibration and noise arise from SCC box girders.The vibration differences between them are around 7.7 dB(A)at the bottom plate,19.3 dB(A)at the web,and 6.7 dB(A)at the flange,while for structure-radiated noise,the difference is around 5.9 dB(A).Then,potential vibroacoustic control strategies for SCC box girders are discussed.As the vibro-acoustic responses of two types of girders are dominated by the force transmitted to the bridge deck,track isolation is better than structural enhancement.It is shown that using a floating track slab can make the vibration and noise of an SCC box girder lower than those of a PC box girder.However,structural enhancement for the SCC box girder is extremely limited in effects.The six proposed structural enhancement measures reduce vibration by only 1.1–3.6 dB(A) and noise by up to1.5 dB(A).
基金supported by the Chinese National Natural Science Foundation (grant number 51977039 and 51950410593).
文摘The multi-port energy router(ER)is an effective topology for integrating train traction load,AC load,the energy storage system and photovoltaic(PV)energy.The start and stop process of urban rail transit trains and the access of distributed energy sources to rail transit ER lead to serious fluctuations of DC bus power,so it is necessary to route energy between different ports,involving multi-operating modes,while seamless switching is a major challenge.In this paper,a hierarchical coordinated control strategy is proposed to enable the multi-port ER to operate in a coor-dinated fashion under the conditions of train parking,acceleration,constant power driving and deceleration,and to switch seamlessly under various working conditions.The energy central dispatching layer sends working condi-tion instructions by sampling the state information of each port,while the microgrid control layer adopts central-ized control,receiving upper working condition instructions and sending drive signals to the local control layers to maintain the balanced energy flow of each port.In the local control layers,the PV adopts the improved perturbation and observation method of power control(PC-P&O),while the ES system adopts voltage loop control with an SOC influence factor,voltage loop control with switching factor and power loop control according to the different working conditions,so as to transmit the required train load power accurately and maintain the stability of the DC bus voltage.Finally,the effectiveness of the proposed hierarchical coordination control is verified by MATLAB/Simulink simulations.
