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The vibration of high-speed trains induced by track irregularities is a main factor affecting ride comfort. Especially, the long-wavelength track irregularities can reduce the passengers' ride comfort by increasing the vibration of the high-speed trains. A three-dimensional human body model coupled to a vehicle body and tracks is established to form a coupled human-seat-vehicle-track system for investigating the influence of the long-wavelength track irregularities on ride comfort. The parameters of the seated human model are determined by measurement based on the multi-island GA method. The coupled model is then used to evaluate the ride comfort of high-speed trains using ISO 2631 under the excitation of the track longitudinal level irregularities. The effects of primary, secondary suspension, and seat support vertical stiffness and damping on ride comfort are analysed. The results show that the track's longitudinal irregularities lead to high human body vibration levels and large ride comfort indices (lower ride comfort), especially when the irregularity excitation frequency is near the natural frequency of the high-speed train. The passengers' ride comfort is more sensitive to the vertical secondary suspension stiffness than the other suspension parameters. [ABSTRACT FROM AUTHOR]

A 3D rigid-flexible human-seat-vehicle-track coupling model is proposed to analyze high-speed train ride comfort. The seated human model is built based on the multi-body dynamic method. The human multi-axis excitation measurement data determines the model parameters. The detailed FE (finite element) car body model is built, and the model is calibrated by laboratory modal tests. The dynamic behavior of the high-speed train, running on both straight and curved tracks, is analyzed by using the rigid-flexible human-seat-vehicle-track coupling model. Then, the effect of the seat support parameters on the ride comfort of the high-speed train is analyzed, when the train travels on curved tracks. The results show that using the rigid car body model can overestimate the ride comfort of the high-speed train. The lateral and rolling motion of the car body, induced by curves can worsen the lateral dynamic performance of the passenger seats. At the different seat positions and for the different configurations of seats (three-abreast and two-abreast), selecting proper stiffness of the seat-floor and seat-sidewall supports can achieve comfort for the passengers. [ABSTRACT FROM AUTHOR]

This paper examines the impact of pay gap on the quality of the internal control. Using state-owned enterprises listed in China from 2012 to 2019 as samples, we find new evidence of an inverted U-shaped relationship between the pay gap and internal control quality, which includes the executives' internal pay gap, external pay gap, and executives-employees pay gap. Furthermore, we also find that there is an inverted U-shaped relationship between the pay gap and the internal control quality in state-owned enterprises with commercial competition, but we don't find similar results for the samples of state-owned enterprises with specific functions. In addition, we provide evidence that the pay gap not only has a direct impact on internal control quality but also has an indirect impact on internal control quality through agency costs. This study supplements research on internal control quality from the perspective of incentives. [ABSTRACT FROM AUTHOR]