Jiangxi Institute Of Economic Administraors

Abstract Due to their large span and complex support conditions, large-span bottom-hinged radial gates are highly susceptible to significant hydrodynamic impacts and vortex-induced vibrations during operation, making fluid-structure interaction (FSI) effects particularly prominent. In this study, the FSI dynamic characteristics of such gates are systematically investigated. A three-dimensional finite element model of the gate is established, and the flow field is simulated using the Volume of Fluid (VOF) two-phase flow model and the RNG k-ε turbulence model using Fluent. The pressure distribution and velocity field characteristics, as well as the displacement and stress of the gate under different gate openings, are analyzed. Results show that during the lifting stage, the upstream flow remains generally stable, with a slight increase in the water surface elevation. In the lowering stage, vortices form near the downstream sill edge during submergence, increasing local sedimentation risk. For both the lifting and lowering operations, the maximum displacement and maximum stress of all gate components gradually decrease with increasing gate opening. The results provide important theoretical support for the safe operation and optimized design of large-span bottom-hinged radial gates.

Abstract Nonlinear energy sinks (NESs) have received widespread attention due to their broadband vibration absorption ability. This article investigates the effect of the NES device on the nonlinear dynamic characteristics of the cable. First, the mechanical model of the inclined cable coupled NES was established. The dynamic equation of the system was obtained by applying Hamilton's principle. Then, the partial differential control equations of the system are discretized by the Galerkin truncation method. The incremental harmonic balance (IHB) method is applied to obtain the steady-state response of the nonlinear vibration of the system. Finally, the effects of the relevant parameters of the NES device on the nonlinear dynamical characteristics of the system are analyzed. In addition, the transient energy transfer within the system is analyzed. The results show that the NES can effectively reduce the displacement response of cable under harmonic loading. The variation of the relevant parameters of the NES device has a significant effect on the dynamic behavior of the cable.

The purpose of this article is to discuss the synchronous stability control strategy of Static var generator under the new electric power system (EPS) model system, so as to meet the voltage stability challenge brought by the high proportion of renewable energy access. In terms of methods, this article first expounds the development trend of new EPS and the important role of SVG in it, and makes clear the necessity and urgency of the research; Then, a new EPS model system including renewable energy, power electronic equipment and intelligent control technology is constructed. Then, aiming at the synchronous and stable control of SVG, this article puts forward a phase angle and amplitude control method based on virtual internal potential, and carries out detailed model construction and parameter setting through simulation software. The experimental results show that SVG can significantly improve the voltage stability of EPS after its introduction. SVG can respond quickly and maintain voltage stability when faced with disturbances such as load change and power supply voltage fluctuation. Through comparative analysis, the effectiveness of synchronous stability control strategy is verified, and the stability and response speed of SVG are evaluated. The research results provide strong technical support for the stable operation and intelligent control of EPS.

Abstract This study examines the mechanical properties and fracture modes of sandstone with single and double cracks under varying confining pressures through triaxial compression tests. The stress–strain curves, mechanical parameters, and fracture modes of both intact and cracked sandstone are analyzed based on experimental results. The study finds that the presence of cracks has a significant impact on the mechanical properties of sandstone, with greater damage observed with an increase in the number of cracks. The peak strength and strain of a cracked rock sample increase with the increase in crack angle. The fracture mode of sandstone is influenced by both crack angle and confining pressure. When the crack angle is small, the fracture mode is a combination of shear and tensile failure, while a large crack angle results in shear failure. Moreover, as the confining pressure increases, the degree of damage to the sandstone also increases.