The railway environmental vibration caused by high-speed railways is harmful to the human health, the structural safety of adjacent buildings, and the normal use of precision instruments. At the same time, it occurs frequently. In this case, the railway environmental vibration has drawn much attention with the rapid development of highspeed railways. Studies in Earthquake Engineering show that a convex topography has a great impact on ground vibrations, however, there is no consideration about the convex topographic effect in the study of the railway environmental vibration when the convex topography is near the roadway. In this paper, the influence of a convex topography on the railway environmental vibration was investigated. Two-dimensional (2D) finite element models consist of subgrade-convex topography and subgrade-flat topography are established using the finite element method. The length and the height of the analysis model are taken as 200 m and 41.3 m, respectively. The external soil of the calculation model is simulated via the artificial boundary. By comparison with measured results, the 2D finite element models were verified to be effective. The convex topographic effect is studied by conducting parameter investigations, such as the bottom width, cross-sectional shape, height-width ratio and the foundation soil properties. Results show that the dimension and cross-section shape of the convex topography and the foundation soil properties have significant effect on the convex topographic effect.

The variable stator vane (VSV) system is a key component of gas turbine supercharged rotor components for anti-surge, and its performance directly affects the working stability and economy of the gas turbine. The effect of the VSV system on the dynamic characteristics and control performance of the gas turbine cannot be known. Then a refined model of the VSV system refined to design parameters established and studied to explore the effect of gas turbine dynamic performance based on co-simulation. The effects of key parameters on the performance of the gas turbine system are analyzed by embedding the refined VSV model into the engine model. The simulation results prove that servo amplifier gain, viscous friction coefficient and dead band are sensitive structural parameters that affect the dynamic performance of the gas turbines. In the proposed appropriate interval, the optimal sensitive parameters can reduce the overshoot and adjustment time by about 51% and 7%. The gain of the servo amplifier is positively correlated with the maximum opening of the VSV. When the dynamic performance of the control system has been exerted to its extreme, some nonlinear parameters of the actuator can greatly improve the overall performance of the complex system.

The inter-turbine burner (ITB) engine, which is introduced ITB between high and low pressure turbines, is a relatively new concept for increasing specific thrust and lowering high altitude specific fuel consumption (SFC) than engine with afterburner. While ITB engine brings outstanding performance improvement, it also brings challenges to the ITB engine control law design under unknown matching mechanism and multi-constraint. In this study, a self-scheduling control law design method for ITB engine mode transition that takes into account the ITB ignition and flameout characteristics and cooling air volume is proposed. This method derives the control law based on the global optimal algorithm and SHAP-value (SHapley additive exPlanation) analysis method, which avoids manual analysis and reduces the number of adjustment of variable geometric components. An ITB transient model is established to verify the control laws under the switching of ignition and flameout modes. Both flow fluctuations do not exceed 2%, and thrust fluctuations do not exceed 4% and 2% respectively. During the transition between the two modes, at most one variable geometry component is adjusted.

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